About IITA The international Institute of Tropical Agriculture (11TA)--one of the major links in a worldwide n c t ~ work of agricultural research and training centers was cstahlished a s a n ;rutonornous, nnnprotit corpor;rtion on 27 July 1967. Thc Federal ltepr~blico f Nigeria alluted 1,000 hectares of land for the TTTA site. and t.he Ford Foundation provided initial capital for buildings and development. IlTA is governed by a n 1ntern;rtional Roard of Trustees, t h e membership of which includes representatives fromdeveloping countries in areas of the Tnstit,ute's concern. The principal financing of the Ins t i tu t ,~(a nd other centers) is arranged by the Consultative Gr l~upo n 1nternation:rl Agricultural Kesearch (CQTAR) an informal group of d ~ ~ n ocor u ntries, development hanks, foundations and agencies. Support for TTTA's research and training core program in 1982 was provided by the Canadian 1nternati11n;il develop^ ment Agency (CIUA), Ovrrseas Devel~lprnent Minist.ry ofthe United Kingdom(ODM), U.S. Agency f International Development (USAID), World Bank, International Fund for Agricultural Develclp- men1 (IFAD), 17ord Foundation, OPEC Fund fix Agricultural Development, and the govcrnments of Australia. Belgium, France, India, Italy, Japan, Netherlands, Nigeria. Norway. and Federal Republic of Germany. In addition, other donors provide funds to the Institute, particularly to support specific research or training programs. The "geographic mandate" of IlTA int:ludes the humid and subhumid trupicalzoncs, and the Institute concentrates its rese;rr~:ha nd training in two major areas: farming systems and crop improvement of certain design;rtrd ccreals (rice and maize), grain legumcs (cowpeas and snyheans), and roots and tubers (yams, sweet potatoes and cassavzr). Correct citation: Inti~niationnl Tnslitute of Tropical Agriculture, 1983, r2nn~!ailKv~oforrt 1982. Ihadan, Nigvria Published hy the Tntcrnational Institute of T~.opical Agriculture. Oyo Road. I'MR 5320. Ihadan, Nigel.in Contents Board of Trustees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cereal Improvement Program . . . . . . . . . . . . . . . . . . . . . . . . . Rice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Genetic Improvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Entomology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Maize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Genetic Improvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Entomology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Virology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SAFGRAD Project in Upper Volta . . . . . . . . . . . . . . . . . . . . . . . . . . . . N C R E P r o j e c t i n C a m e r o o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Maize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sorghum and Millet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Grain Legume Improvement Program . . . . . . . . . . . . . . . . 51 Cowpeas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Genetic Improvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Entomology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Virology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 SAFGRAD Project in Upper Volta . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 Soybeans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Genetic Improvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Entomology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Virology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Microbiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 Root and Tuber Improvement Program . . . . . . . . . . . . . . . 89 Cassava . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Genetic Improvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Entomology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 Virology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Agronomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Quality Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Y a m s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Genetic Improvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Virology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 S w e e t P o t a t o e s. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 Cocoyams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Genetic Improvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Agronomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 Nematology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 T i s sueCul tu re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 C ~ t o g e n e t i c .s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 Farming Systems Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 Soil Managemen t a n d L a n d Development. . . . . . . . . . . . . . . . . . . . . 120 Wetlands Characterization and Evaluation . . . . . . . . . . . . . . . . . . . . 120 SoilDegradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 SoilErodibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Organic Residues and Fertilizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Seedbed Preparation and Tillage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Land Clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Cropping Sys t ems and Managemen t . . . . . . . . . . . . . . . . . . . . . . . . . . 141 Multiple Cropping and Rotations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 WeedManagement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Agroforestry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 Live Mulches and Cover Crops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 F a r m I n p u t s a n d Equ ipmen t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 No-Tillage Sprayers for Small Farms . . . . . . . . . . . . . . . . . . . . . . . . . . 16'3 Comparison of Cowpea Harvesting Methods . . . . . . . . . . . . . . . . . . . . 166 Evaluation of Low-Horsepower Equipment . . . . . . . . . . . . . . . . . . . . . 167 ProductionEconomics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 Cooperatives and Group Farms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 Technology Trans fe r a n d Tra in ing . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 The Methodology of On-Farm Adaptive Research . . . . . . . . . . . . . . . 174 An Approach to On-Farm Adaptive Research . . . . . . . . . . . . . . . . . . . 176 Cooperat ive Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 MIDAS Project i n Ghana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 ZAPI-Est Project in Eastern Cameroon . . . . . . . . . . . . . . . . . . . . . . . . 182 Farming Systems Research Network in East Africa . . . . . . . . . . . . . . 186 Training Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 International Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 Research Support Units . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 FarmManagement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 Genetic Resources Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 Virology Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 Analytical Service Laboratory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 Library and Documentation Center . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 Public Affairs and Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 Appendix 1: The Weather at IITA . . . . . . . . . . . . . . . . . . . . . . 206 Appendix 2: List of Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . 208 List of Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 Collaborators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 Conference and Seminar Papers . . . . . . . . . . . . . . . . . . . . . . . 215 Board of Trustees Mr. Guy Vallaeys (Chairman) Deputy Director General, Institute for Tropical Agricultural Research (EAT), Paris, France. Mr. D.E. Iyamabo (Vice-Chairman) Director, Department of Agricultural Sciences, Federal Ministry of Science and Technology, Lagos, Nigeria. Dr. R.C. McGinnis Dean of Agriculture, University of Manitoba, Winnipeg, Canada. Dr. Hidetsugu Ishikura Director General, Institute of Environmental Toxicology, Tokyo, Japan. Mr. Alhaji M. Liman Permanent Secretary, Federal Ministry of Agriculture, Lagos, Nigeria. Dr. E.H. Hartmans Director General, IITA, Ibadan, Nigeria. Prof. R.J. Olembo Division of Ecosystems and Natural Resources, UNEP, Nairobi, Kenya. Citoyen Mukendi Mbuyi Tshingoma Food and Agriculture Organization (FAO), Bamako, Mali. Dr. John J. McKelvey, Jr. Rockefeller Foundation, New York, New Y ork. Prof. C.A. Onwumechili Vice-Chancellor, University of Ife, Ile-Ife, Nigeria. Dr. E. de Langhe Laboratory of Tropical Crop Husbandry, Catholic University, Heverlee, Belgium. Mr. M.S.O. Nicholas Director, Agricultural Services Division, Food and Agriculture Organization (FAO), Rome, Italy. Foreword For the first time in this quinquennium, the overall financial position of the Institute has taken an upward swing. This reversal has made it possible to restore some scientific positions, maintain a full complement of junior scientists, double the participants in training courses, replace obsolete equipment, and make modest improvements in the physical p1ant~-all of which have contributed to improved staff morale and program accomplishments. The Institute, in preparation for the forthcoming second quinquennial review, has reappraised its long-range plan, evaluated program gains, and has more sharply defined its activity profile for the years ahead. It has escalated the decentralization of a range of activities and is increasing its collaboration with international, regional and national institutes by placing some of its key staff memhers in strategic locations in order to make the needed impact a t national levels. Transcending its classical role in technology generation, the Institute has launched an ambitious program for on-farm research in Africa. The attention of policy makers and research leaders indeveloping countries is being drawn to the relevance of IITA technology for overall conservation of natural resources and for a rapid step-up in food crop production in Africa. The Annual Report, Research Highlights and other special publications, such as Appraisal of the Tasks for the Eighties and Food Crisis in Tropical Africa, give an overview of the Institute's research objectives, thrust and output. Readers interested in scientific details not covered in these reports should consult the journal articles listed in the back of this publication or contact the scientists. IITA has recognized from its inception that the retention of soil organic matter is most crucial for the maintenance of soil fertility in the tropics. As a result of its ongoing farming systems research, the Institute has established that the maintenance of organic matter a t adequate levels can be accomplished by various options~--no-tilfl arming, alley cropping, live mulches, crop rotations, etc. The Institute has developed plans to put into effect a number of these options a t the small farm level both on and off site. The genetic improvement of crops-maize, rice, cowpeas, soybeans, cassava and yams-has progressed to the point that elite germplasm with several valuahle traits is being released to farmers by national programs in Africa and Latin America. The impact of IITA's current crop improvement programs is increasingly evident in many countries in the tropics. However, the grcat diversity of the African "food basket" leaves no other option for IITA than to simultaneously address the genetic improvement of all the more important food crops, and concentrate a t any given time on the most critical production problems in them. The Institute may have to step up its research on starchy hananas, a key food crop in thc humid tropics. Highly significant in TITA's crop protection research is the rapid development of biological control technology against the ravaging insect pest, cassava mealybug. A major regional biological control program will soon be launched by the Institute. Breeding for genetic resistance to cassava. mealybug, cassava green spider mite, and bruchids, thrips and aphids in cowpeas is producing equally satisfying results. The team of scientists and the management a t IITA take this opportunity to acknowledge the generous support of its donors and the willing cooperation of innumerable national scientists and policy makers in making it, possihle for the Institute to be effective in carrying out its mandate. ERMOND H. HARTMANS Director General M AIZE ANDRICE are two of the most important Projects (ADPs). An entirely new dimension was cereal crops in Africa. Although the area added to the program in 1982 when a special project planted to rice is still relatively small, fordeveloping hybrid maize varieties was initiated at demand for this crop has been growing steadily. This IITA, with the support of the Nigerian government. increased demand reflects the shift in diet that has resulted fromurhanization. Maize, one of the leading Rice crops cultivated in Africa south of the Sahara, is widely used for human consumption and is The principal objective of IITA's rice improvement increasingly in demand for poultry feed. Even program is to increase rice production in Africa countries that have not traditionally been maize through research on dryland, hydromorphic and consumers are becoming interested in growing this irrigated/shallow swamp ecologies. Our strategy for crop to reduce reliance on imported supplies in their solving the problems that limit rice yields is first poultry industries. Both rice and maize have to develop superior adapted varieties that have immense potential in Africa for yield improvement resistance to stresses common in rice growing and expansion of the area cultivated. regions and second to come up with appropriate The Cereal Improvement Program a t IITA is cultural practices that improve the performance of helping Africa develop that potential by producing those varieties. improved rice and maize varieties and by seeking In 1982 screening for important African problems. solutions to specifically African problems. The such as hlast, rice yellow mottle virus (RYMV), stalk- program is placing particular emphasis on disease eyed fly (Diopsis thoracica), drought, soil acidity, iron and insect pest resistance and drought tolerance. In toxicity and cold, received greater emphasis. A wide these efforts it is working closely with national range of germplasm, introductions and breeding programs through the High Yielding Varieties materials from various national and international Technology (HYVT) Project, which was begun crop improvement programs was systematically toward the end of 1981 with aid from the European screened, and several cultivars that are tolerant to Economic Community (EEC). This year also saw the above problems were identified. the heginning of a new cooperative program in High tolerance to RYMV was found to be Cameroon, the National Cereals Research and associated with 0. glaberrima and with 0. sativa Extension Project (NCRE), which is being carried cultivars that are adapted in Africa and their out hy ITTA staff and is funded by USAID. derivatives, such as the ITA cultivars. Most The program has also benefitted greatly from its introductions, however. proved to be either involvement with two regional organizations: the susceptible or only moderately tolerant when seed- Semi-Arid Food Grains Research and Development lings were innoculated. A mass screening technique (SAFGRAD) Project and the West African Rice for Diopsis was developed, and a number ofpromisiny Development Association (WARDA). The former, cultivars were identified. which is being carried out by IITA maize scientists, In addition to developing cultivars that are has organized multilocational testing of maize tolerant to iron toxicity through conventional varieties in 24 member countries in the semiarid breeding methods, IITA rice researchers irradiated zone. IITA is participating in WARDA's multilo- with gamma rays seeds of Gissi 27, a local selection cational testing program and has posted a scientist from Liberia that is highly tolerant to iron toxicity. with that organization. Among the mutants, semidwarfs and photoperiod In 1982 the Cereal Improvement Program con- insensitive selections were identified. tinued to work closely with the International Rice Because drought was severe in 1982, we were able Research Institute (IRRI), Institut de Recherches to evaluate a large number of breeding lines for Agronomiques Tropical (IRAT) and Centro Inter- drought resistance in several locations and identify national de Majoramiento de Maiz y Trigo new promising selections. This work confirmed our (CIMMYT). All three of these institutes have previous observations that ITA 116,117,118,135a nd scientists a t IITA participating in its research. 235, among others, have high drought resistance. The program also continued cooperative work Systematic screening for adaption to low pH, acid with its host country, Nigeria. IITA scientists soil was begun a t our high rainfall station at Onne in actively participated in annual meetings and strips varying in soil pH with and without applied workshops of the Nigerian National Cereals P205f ertilizer. The unadapted cultivars showed very Research Inst i tute (NCRI) and the National poor vigor, produced highly discolored grains or Accelerated Food Production Project (NAFPP). dirty panicles and suffered from blast, leaf scald and Improved rice and maize varieties developed a t IITA sheath diseases. This work is showing promise and are now being nominated for nationwide trials, and will be continued. breeder seeds are being supplied to the National Seed As part of the recently begun NCRE project in Service. Close links were also established with the Cameroon, IITA researchers evaluated for tolerance World Bank-supported Agricultural Development to cold, sheath rot, blast, leaf scald and drought. 4 Cereals Their tests indicated that the primary need is to At Ihadan, as at Ikenne, rainfall is bimodal (1,300 incorporate resistance to sheath rot and blast into mm annually), but the gravelly soils there have lower cold tolerant cultivars in Africa. The superior water holding capacity than the Ikenne soils. Similar cultivars emanating from the various screening tests conditions are found in parts of Ivory Coast, Ghana, are being included in the hybridization program and Benin and Togo. In 1982,610 Fq and later generation evaluated for direct use by national programs. lines were grown a t Ibadan. Fl plants from 68 crosses Two major events in which the rice program took were also grown there under paddy conditions. part in 1982 were the Upland Rice Workshop and Because stresses were severe a t these locations in Monitoring Tour, which was sponsored by IRRI, 1982, selection pressure was high, allowing only a IDESSAIIRAT (Institut des Savanes), IITA and limited number of outstanding lines to be selected for WAKDA, and the High Yielding Varieties Tech- further evaluation. Blast, leaf scald, sheath rot, and nology Project Workshop. panicle discoloration diseases were prevalent a t Participants in the Upland Rice Workshop and Onne. Primary emphasis was placed on observation Monitoring Tour observed differences among upland of harvested grain for selection of lines that were free rice environments and proposed that breeding for of panicle discoloration. Fifty-three F3 and 86 F4 and upland rice be done on a regional basis. The HYVT later generation lines were selected. Project Workshop proposed that IlTA pay special At Ikenne and Ihadan, severe drought occurred attention to the major problems with rice production from mid-July to mid-August. Many lines were in or in all ccologies of eastern, central and southern near the hooting stage a t that time. Blast and leaf Africa. scald were common at bothlocations, and neck blast, Rice trials were organized in cooperation with sheath rot, and leaf spot were particularly prevalent NCRIINAFPP, the Agricultural Projects Monitor- a t Ikenne. But even under high drought and disease ing, Evaluation and Planning Unit (APMEPU) in stress, we were able to select 37 F3lines and27 Fq and Kaduna, and with various river basin development later generation lines a t Ikenne and 52 F4 and later authorities. Through these trials IITA researchers generation lines at Ihadan that were superior to the identified superior dryland (ITA 116, 117, 135 and check cultivars. These lines are being multiplied 235). iron toxicity tolerant (ITA 238,239,247,253 and during the dry season and will he included in TOx 711-18-18) and irrigated (ITA 121, 123 and 212) observational nurseries and/or yield t,rials in 1983. rice cultivars that could be used in the future for The 95 F2 populations a t Ikenne were less affected extensive cultivation. by stress conditions than those a t Ibadan because they escaped drought during the reproduction stage Genetic Improvement and had wider row spacing. Forty-two single plants were selected from 13 of the populations; 26 single Early Generation Material plants and selected bulks from 11 of them; 18 In continuation of their efforts to develop high populations were selectively bulked; and 53 were yielding, high quality rice for African ecosystems, rejected. Selection was based primarily on plant IITA rice scientists evaluated early generation type, large panicles and clean grain. These selec- upland rice hrceding lines during 1982 a t three tions will be screened for hlast and RYMV at IITA locations in Nigeria-Onnc, Ikenne and Ibadan. and included in multilocational trials during 1983.-~ Onne is characterized by high monomodal rainfall K. Alluri and J . W . Gibbons ( > 2 ,400 mm annually), highly weathered acid soils Upland Elite Yield Trials and low solar radiation. Conditions there are similar to those in Liberia, Sierra Leone, Cameroon, Gabon, The objective of the upland elite yield trials was to and Ivory Coast. At that location 280 Fy and 681 F4 test the adaptability of varieties at several sites in and later generation lines were evaluated. They were Nigeria (Onne, Ikenne, ibadan, llorin and Zaria) that sown on 24 May in three-row plots 5 m long. ITA 212 represent the major upland ecosystems of West (lowland semidwarf), TTA 117 (carly maturity), ITA Africa. Onne, which is located in the southeastern 116 (medium maturity), LAC 23 (tall African rain forest, has a long, monomodal rainy season. selection), and OS 6 (a farmers' variety) were Ikenne, Ibadan and Ilorin are all in the bimodal zone included as check cultivars. A disease spreader (at Ibadan the medium duration trial was also grown composed of a mixture of blast susceptible cultivars under hydromorphic conditions). Zaria, which is in bordered every block. the northern savanna has a short, monomodal rainy At Tkenne, which is in the bimodal rainfall zone season. (1,600 mm annually) and where conditions are like Two sets of varieties were planted, one of short those in Benin, Togo, Ivory Coast and Tanzania, the duration (about 70 days to heading and 100 days to same breeding materials as those used a t Onne were maturity) and another of medium duration (about 95 planted on 6 Junc following the same design. In days to heading and 125 days to maturity). Each set addition, 95 populations were planted there on 10 included a typical lowland variety (TOs 103, a short July. The F2 seeds were lightly drilled, and the row duration variety, and ITA 212, which has medium spacing was 40 cm. Tall segregants were eliminated duration) and OS 6, a common check. Each set was as soon as they were observed. sown in a randomized complete block design, with Cereuls 5 four replications a t all five locations . Each plot was but blast (I'yricularin or,yznt.) was nuwhrre evident . 151112 with row spacing of 30 cm. and the seeding rate The erratic perfnrmance of the short duration was 50 kg/ha. Fertilizer (15-15-15) was applied a t a varieties can be attributed to variation in stresses rate of 300 kg/ha a t planting. followed by 100 kg across locations . Yields were generally higher at urea/ha one month later . Weeds and pests were Onne. where there was no drought. ITA 117 and lKAT controlled as required . The sowing dates ranged from 112 gave the highest yields. over 3 t /ha (Table 1). the end of March a t Onne to the end of June a t Zaria . Several entries in this trial performed well at Zaria; Rainfall was high a t Onne from sowing through their short growth duration made them suitable for harvest . At Zaria rainfall was adequate from sowing the short rainy season of that region and enabled to heading but after mid-September was insufficient them to escape drought. R A T 112. 133 and 109. TOx for good grain filling. At Ikenne. Ihadan and Ilorin. a 1011-4-1 and ITA 150 each yielded more than 2 t/ha. very severedrought spell occurred in mid-July to late ITA 117. ITA 132 and TOx 103 gave very low yields a t August . At Onne sheath rot (Acrocylindrium oryzae) hoth lkenne and Zaria on account of their slightly and glume discoloration syndrome were very severe. longer duration. which led to drought stress at the resulting in poor grain quality. Leaf scald (Rhyncho- grain filling stage. R A T 133. 109 and 110. TOx 1011~4.1 sporium oryzae) and brown spot (Helminthosporium and ITA 150 yielded 2 t or more a t hoth lbadan and oryzae) diseases were common a t the other locations. Ilorin . At the four locations where drought was a Table 1. R e s u l t s of up l and r i c e e l i t e yield trials. Nigeria . 1982 Yield. t/ha Variety Onne Ikennr lbadan I l o r i n Zaria Ibadana Mran Early m a t u r i n g RAT133 . . . . . . . . . . . . . . . . . . . . . . . . 2.9 1.6 2.3 3.1 2.6 2.5 IRAT 109 . . . . . . . . . . . . . . . . . . . . . . . . 2.8 1.6 2.1 3.4 2.3 2.4 lRAT 112 . . . . . . . . . . . . . . . . . . . . . . . . 3.2 1.8 2.0 1.8 2.7 2.3 IRATI10 . . . . . . . . . . . . . . . . . . . . . . . . 2.3 1.7 2.3 2.7 1.9 2.2 TOx 1011-4-1 . . . . . . . . . . . . . . . . . . . . 2.6 1.6 2.1 2.2 2.5 2.2 ITA 150 . . . . . . . . . . . . . . . . . . . . . . . . . 1.7 2.1 2.0 2.0 2.2 2.0 ITA 120 . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 1.5 1.8 1.5 1.8 1.7 ITA 117 . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 0.3 1.2 2.9 0.4 1.6 IAC 25 . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 1.7 1.9 2.2 h 1.6 ITA 132 . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 0.3 2.5 1.1 0.4 1.3 TOs 103 . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 0" 1.0 0.7 0.3 1.0 OS6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7 0.2 0.5 1.1 od 0.7 Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 1.2 1.8 2.0 1.6 Medium d u r a t i o n ITA 141 . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 1.4 1.1 0.9 0.1 4.2 1.2 lTA235 . . . . . . . . . . . . . . . . . . . . . . . . . 0.6 1. 2 1.9 1 .3 1.1 3.4 1.2 ITA 182 . . . . . . . . . . . . . . . . . . . . . . . . . 0.6 1.0 1.6 1.3 0.9 2.5 1.1 ITA 138 . . . . . . . . . . . . . . . . . . . . . . . . . 0.9 1.0 1.2 1.2 0.7 3.2 1.0 ITA 162 . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 1.2 0.8 0.9 0.9 2.3 1.0 ITA 118 . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 0.9 1.2 1.0 0.7 3.0 0.9 IRAT13 . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 0.5 0.9 1.3 0.3 3.0 0.9 ITA142 . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 2.2 0.1 0.7 0.1 3.3 0.8 TOx 718 . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 0.5 1.2 0.7 0.4 2.6 0.8 ITA116 . . . . . . . . . . . . . . . . . . . . . . . . . 0.9 0.7 0.3 0.8 0.7 3.4 0.7 IR52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 1.8 Or 0.1 0' 4.4 0.7 ITA 256 . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 1.7 0.2 0.4 0.1 4.0 0.6 OS6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 0.6 0.5 0.7 0.1 3.0 0.4 ITA178 . . . . . . . . . . . . . . . . . . . . . . . . . 0.9 1.1 0.7 h 0.6 5.2 ITA 212 . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 2.1 0.3 b OC 6.8 Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 1.2 0.8 0.8 0.6 3.2 0.9 LSD (.5. %."). . . . . . . . . . . . . . . . . . . . . . . . . 0.2 0.2 - 0.3 0.5 C.V.. x. . . . . . . . . . . . . . . . . . . . . . . . . . 33.22 27.0 42.9 54.2 "At lbadan mt-dium duration varieties were tested under hydromorphic as well as upland conditions . hNot testcd . 'Drought sterility . dPlots missing . 6 Cereals problem. IRAT 133, 109, 112 and 110, TOx 1011.1 and Lowland Observational Nurseries ITA 150 gave consistently better yields than the other varieties. Lowland observational nurseries were conducted a t The performance of medium duration varieties Ibadan under hydromorphic conditions in coopera- across locations was even more erratic than that of tion with the Animo Rice Project (funded by the the short duration varieties. Four varieties, ITA 118, World Bank) a t Amaeke Abam (near Bende) and Uzo- E A T 13, IR 52 and ITA 212, yielded 1.5 t/ha or more a t Uwani in Nigeria. At the latter two locations the Onne, where drought stress was minimal (Table 1). nurseries were in rice farmers' fields. At Ibadan the T,ow yields at Ikenne, Ihadan and Ilorin were due nursery was composed of 221 lines from 26 Fq and largely todrought, associated withpaniclediscolora- later generation families and of 54 introductions tion, which resulted in poor grain filling. At all three from international trials. IR 50, ITA 212, ITA, 123, locations, the performance of TTA 235 was superior and ITA 121 were included as checks. Twenty-six because of its high degree of drought tolerance. ITA lines from 10 Fq and later generation families and 30 141, 182 and 138 also gave good yields in spite of introductions from international trials were grown severe drought a t all three locations. All the test at Amaeke Abam and Uzo-Uwani. Plot size was 5 m2 entries performed very poorly a t Zaria for two at Amaeke Abam and Ihadan and 3.3 mL a t Uzo- reasons. First, the growth duration of the varieties Uwani. Plant spacing was 25 cm x 20 cm. The trial was too long for that region's short, monomodal was unreplicated. Plant height, panicle number per rainfall pattern. And second, drought stress was plant, days to 50%, flowering, plot yield, vigor, and unusually severe during 1982. As a t other locations, leaf and neck blast scores were recorded. ITA 235 gave the highest yield because of its high The major stresses were leaf and neck blast, leaf degree of drought tolerance. IR 52 and ITA 212 were scald, and brown spot diseases at Ibadan and comparatively sterile at Ibadan and Zaria because of imbalanced soil nutritional status (particularly low severe drought stress a t grain filling. N and high Fe) resulting from fluctuations in the These two trials indicate that in 1982 the early water table and improper drainage. Under these conditions 67 selections were made from 17 families duration varieties generally performed better than the medium duration varieties because they escaped and 10 selections from the introductions. These drought, especially a t the grain filling stage. J. selections will be advanced to preliminary yield Arriuets, K. Alluri and J. W Gibbons trials in 1983. In addition, seven lines from these trials were included in the crossing program to be Screening for Acid Upland Soils used as sources for disease resistance, yield potential and plant type characteristics. Thirty-one cultivars and 30 Fq and later generation lines from IITA and 30 entries in IRRI's acid upland Lowland Advanced Yield Trials screening set were screened for acid tolerance a t IITA's high rainfall station a t Oune, Nigeria. Each For the advanced yield trials carried out in 1982, 35 entry was sown in two rows 4 m long in a control (pH superior cultivars were selected from the 1981 4.6) and an acid strip (pH 3.9). Nitrogen was applied varietal trials of IITA, WARDA, IltRI and national at a rate of 60 kg/ha on both areas, and 60 kg P205/ha programs. The cultivars were divided into three was applied on the control strip only. Vigor and trials based on their maturity time. The short panicle exertion scores. panicle number, plant duration trial (100 to 115 days) consisted of 11 height, days to 50'yu flowering and plant yields werc cultivars, and the medium (116 to 135 days) and long recorded. Yields and panicle number tended to be duration (136 days and above) trials were each lower in the acid strips, although the following composed of 12 cultivars. These tr ials were entries were less affected than the others by the acid conducted a t Ibadan (one irrigated and one conditions: ITA 118, 117, 132, 134, 235, 141, 142, 150, hydromorphic location) and at two other Nigerian 162, 178, 212, TOx 936-97-3-1,T Ox 1011-4-1,T Ox 1012- locations, Bende and Uzo-Uwani, in cooperation 12-3,T Ox 1177-17-1,t hree lines from TOx 1766, CICA with the Animo Project,. 8, IR 11288B-6-288-3,I R 36, IR 43, IR 52, IR 5931-110-1, In all trials 30 kg/ha each of N, Pz05a nd K 2 0w ere and IR 6032-10-1-1. applied before transplanting and 20 kg N/ha were Observations made during 1981 a t David, Panama, applied twice a t three and six weeks after planting. A on soils with pH 4.5 and high aluminium in the randomized complete block design was used with internat,ional upland rice observational nursery three replications; plant spacing was 25 cm x 20 cm. (IITA, Annual Report for 1981) indicated that ITA Water control in the irrigated paddies a t Ibadan 116,117,118,225,235, R A T 13, IAC 197 and Azucena was optimal, and no severe stresses occurred. The were superior among the 100 entries evaluated. hydromorphic trial was damaged by birds andrats, so Similar observations were made in Peru this year. the results are not reported here. At Bende and Uzo- All of these ITA lines were selected a t Onne. The Uwani, water control was suboptimal, closely results indicate that superior selections can be made approximating farmers' conditions. at Onne for acid tolerance. This work will be In the long duration trial, ITA 236 and ITA 239 intensified by the IITA rice scientist now posted at ranked highest in yield, on the average, across the Onne.-K. Alluri and J.W. Gibbons three locations, followed by IET 6279 from India and Cereals 7 Table 2 . Results of lowland rice advanced vield trials . Nieeria . 1982 Yield. t/ha At Ihadan Plant Days to Cultivar lhadan Bende Uzo-Uwani Average height. cm maturi1.y Medium duration ITA 222 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.91 5.79 3.74 5.48 104 124 BG 90-2 (check) . . . . . . . . . . . . . . . . . . . . . . 6.69 4.68 5.03 5.47 104 122 Cisadane . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.47 5.44 5.33 5.41 118 130 ITA 212 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.36 4.48 4.69 5.18 100 123 6838 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.00 4.68 4.53 5.07 103 120 ITA 121 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.29 5.17 4.03 4.83 105 123 IR 4422.98.3 . . . . . . . . . . . . . . . . . . . . . . . . . . 4.77 4.88 5.50 5.05 114 130 lR42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.45 4.99 5.02 4.82 106 130 LR 17488-2-3-2. . . . . . . . . . . . . . . . . . . . . . . . 4.90 5.17 3.94 4.67 99 130 TOs 78 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.21 4.29 5.01 4.50 96 122 ITA 231 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.84 3.09 4.19 4.37 99 121 ITA 123 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.15 3.04 3.05 3.75 104 115 LSD (5%). . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.49 1.06 1.18 C.V.,?, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.0 13.5 15.4 Long duration ITA 236 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.96 5.87 4.65 5.49 122 132 ITA 239 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.19 5.58 4.65 5.47 130 132 IET 6279 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.77 6.75 4.70 5.41 128 142 IR 5 (check). . . . . . . . . . . . . . . . . . . . . . . . . . 5.35 5.40 5.31 5.36 125 138 ITA 238 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.32 5.57 4.64 518 127 137 ITA 240 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.85 5.50 4.95 6.10 134 141 ITA253 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.01 5.18 5.10 5.10 135 135 FAR0 I5 (check) . . . . . . . . . . . . . . . . . . . . . 5.48 5.35 4.36 5.06 135 139 ITA 247 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.10 5.28 4.69 5.0'2 142 145 ITA 245 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.84 4.83 4.82 4.83 116 137 ITA249 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.26 5.24 4.63 4.71 136 135 ITA237 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.15 5.08 4.24 4.49 119 137 LSD (5%) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.17 1.13 0.73 C .V . ,%. . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 12.2 9.2 IR5(check)fromlRRI (Table 2) .At Ibadan there were Table 3 . Results of a lowland rice advanced yield no significant differences between cultivars . At trial. short duration. IITA. 1982 Bende IET 6279 was superior in yield to all the P..l..a.n..t cultivars tested. except ITA 236 . At Uzo-lTma~~thie Yield, height, Days t.n two highest yielders. If3 5 (check) and ITA 253. Cultivar ~ j n a crn maturity performed significantly better than the check FAR0 KN144 . . . . . . . . . . . . . . . . . . 6.59 110 112 15 and ITA 237 . IR 2042-178-1 . . . . . . . . . . . . . 6.58 104 106 In the medium duration trial. ITA 222. BG 90-2 TOs 103 (FAR0 27) . . . . . . . . 6.04 79 98 (check). Cisadane and ITA 212 gave the best yields Taichung San Yu . . . . . . . . . 5.87 95 95 (Table 2) . But the two top yielders. 1TA 222 and BG 90- Bouake 189. . . . . . . . . . . . . . . 5.49 114 111 2. have two common defects: they are susceptible to RPT 1235 . . . . . . . . . . . . . . . . blast disease. and their grains are chalky . Cisadaue BC 367.4 . . . . . . . . . . . . . . . . . performed well a t all three locations . ITA 212. as stated in last year's 1ITA Annual Report and again BKNLR 75001.83 . . . . . . . . . . 3.42 101 94 elsewhere in this report. is moderately resistant to BC 276.5 . . . . . . . . . . . . . . . . . 3.31 99 90 blast. and its grains are not chalky . ITA 123. which was superior in last year's trials and this year in LSD(5%) . . . . . . . . . . . . . . . . 2.08 C.V.,?,. . . . . . . . . . . . . . . . . . Cameroon. suffered from r a t damage a t Bende and 24.1 Uzo.Uwani . The short duration trial was conducted only a t construction of irrigation dams and initiation of Ibadan . Three cultivars. FARO 27. K N 144 and IR certain agricul tural development projects has 2042.178.1. yielded more than 6.0 t /ha (Table 3) . I n the encouraged farmers to attempt to grow two or three past little emphasis has been placed on early rice crops a year . Emphasis will be given to maturity since most traditional African farmers identifying and developing short duration grow only one rice crop per year . However. cu1tivars.-K. Alluri and J . Arriuets 8 Cereals Screening for Iron Toxicity Tolerance six entries fkomTRAT, seven from IITA, and two from other sources. All suffered severe drought stress a t Screening for iron toxicity tolerance was conducted a t two locations in Nigeria, Ito-Ikin and Bende. At the tillering stage and intermittent drought stress a t the reproductive stage. The dwarf variety D J 12-539-2 Ito-Ikin 24 F3 lines from seven families and 24 Fq lines from TOx 711 were sown in two replications on 31 from Djibelor, Senegal, produced the highest yield, while IRAT 109, ITA 132 and ITA 118 gave yields of July, with plant spacing of 25 cm x 20 cm. The iron toxicity screening set from IRRI, which is composed more than 3 t /ha (Tahle 5). Drought tolerance ratings of 20 lines, was also sown. Iron toxicity scoring was were highest for ITA 235, TOx 718-1-23a nd IRAT 110, all of which had good panicle exertion under severe done with IRRI's IRTP Standard Evaluation System. In addition to the screening test a t Ito-Ikin, 10 IITA drought. IITA lines in general had better grain cultivars and FARO 15, a local check, were grown in characteristics (grain length and translucency) than large plots of 120 m2. On 6 July the seeds were drilled IRAT lines. Among IRAT entries, IRAT 112 had the a t a row spacing of 30 cm. The plots were flooded best grain characteristics. Despite severe drought, leaf and neck blast were minimalin the test. IRAT 110 when plants were 15 cm tall. At Bende small plot size (4 m x and IRAT 133 were moderately susceptihle t o grain 6 m) allowed testing only of selected advanced discoloration and sheath rot. lines and cultivars. At both locations susceptible (IR 5) and resistant (IR 36) checks were included for WARDA coordina ted var ie ta l t r ia l , upland, comparison of toxicity symptoms. Eighteen single plants from four Fy families that had green leaves and good tillering were selected a t fkom other sources. Severe drought stress occurred a t Ito-Ikin for advancement and further testing in 1983. the tillering stage and intermittent drought stress a t Among TOx 711 Fq lines, nine had good Fe toxicity the reproductive stage. SEL IRAT 194/1/2 produced ratings as well a s other desirable traits such as the highest yield, followed by IRAT 104, 156,170 and earliness and vigor. These lines will be screened for 138, all of which yielded more than 3 t / ha and blast and KYMV and included in preliminary yield significantly more than the check variety ITA 141 trials and in our breeding program. IR 48, IR 4227.109- (Table 5). The entry R9-1-6-1-3-1-1b, ecause of its long 1-3-3, IR 14632-2-3 and B 2149b-Pn26-1-1 were the growth duration and consequent high grain sterility, superior selections from the IKRI set. These require gave the lowest yield. ITA 162 was the only IITA line further testing for adaptability to African con- that gave higher yields than the check. SEL IRAT ditions. In t h r large-plot yield trials, iron toxicity, 194/1/2, IRAT 104 and IRAT 170 were observed to he sheath rot and brown spot were major stresses. ITA very good in drought recovery. Leaf and neck hlast 121 and ITA 247 each yielded 3.0 t /ha, and ITA 250 were insignificant in this trial. IRAT 169 was yielded 2.7 t /ha in spite of stress conditions. Thc moderately susceptihle to sheath rot. ITA 162, IRAT check, FARO 15, produced 1.9 t/ha. At Bende, where 132 and ITA 141 were superior to the other entries in the susceptible check 1R 5 did not grow, ITA 238,239, grain length and endosperm chalkiness. 246,247 and TOx 711-18-18e xhibited fewer symptoms WARDA coord ina t ed va r i e t a l trial, moi s t than the resistant check IR 36. J. W. Gibbons zone, i rr igated, s h o r t dura t ion . In this trial, which International Trials included 15 entries, with IR 36 as the check, KN 144 pruducwl the highest yield (7.2 t/ha), followed by BR 11'1'A c o o p e ~ ~ V~V ; L~~ . r l~ Ll le rl nternational insti- 541-BKN-19-3-4( 6.8 tiha) and IR2928-7-3-1-1( 6.6 t/ha). tutes IRRI, WARDA and Centro lnternacional IR 36, the earliest of the entries tested, was damaged de Agricultura Tropical (C1AT)-by exchanging germplasm; conducting the Internat ional Rice Table 4. Number of IITA lines nominated for Testing Program (IKTP) trials, which are coordi- international rice trials, 1982 nated by IRRI, and the coordinated varietal trials and Number o~ f~ initial evaluati(1n tests of WARDA; and by nomi- Name of trial varieties nating entries for these testing networks. Tahle 4 International rice ohservational nurserv. (shows the number of IITA lines nominated for the .I KON). . . . . 11 International upland rice observational nursery various trials in 1982. (IURON) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 All WARDA and IRTP trials were conducted a t International rainfed lowland rice observational Tbadan, except the screening for tolerance to acid nursery (IRLRON) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 upland soil a t Onne and t o iron toxicity a t lto-Ikin. International rice blast nursery (IRBN). . . . . . . . . . . . . 21 Irrigated rice yield nurseries had three replications, WARDA initial evaluation tests while upland yield nurseries had four, with a Upland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 randomized plot design. Observational nurseries and Irrigated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 initial evaluation tests were evaluated in two-row WARDA coordinated varietal trials plots 5 m long. The results of those trials are Uplandsavanna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Upland moist zone, short duration . . . . . . . . . . . . . . . 2 presented in the paragraphs below. Upland moist zone, medium duration. . . . . . . . . . . . . 2 WARDA coordina ted var ie ta l t r ia l , upland, Sahel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 mois t zone, s h o r t dura t ion . This trial consisted of Moist zone, irrigated . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Cereals 9 by birds, so the yield figure listed in Table 6 does not TTA 212 also produced the highest yields (5.8 and 4.9 reflect its true yield potential. KN 144 also produced t/ha. respectively) in the 1981 WARDA irrigated. the highest yield (7.3 kg/ha) in the 1981 WARDA medium duration trial, which was conducted at 14 coordinated varietal trial a t Thadan. BR 508-B-2-9 different locations in West Africa. ITA 212 was lodged very badly in this trial even before flowering. slightly shorter in growth duration and plant height in spite of its intermediate stature (110 cm). Two than IR 4422-98-3-6-1,h ut both had excellent grain other selections that produced higher yields than the characteristics. Bouake 189. an IRAT nomination. mean, TOs 103 (from IR 790-35-5-3) and IET 4056, was a selection from B 189h-52-8-3-1 from the possessed superior grain quality. Philippines. WARDA coord ina t ed va r i e t a l t r i a l , m o i s t WARDA ini t ia l eva lua t ion t e s t , upland. This zone, i rr igated, m e d i u m dura t ion . In this trial of trial consisted of 99 entries from IRAT, IITA. the 15 entries, IR 4422-98-3-6-1g ave the highest yield (8.4 IItTP trials and national breeding programs in West tiha), as shown in Table 6, followed by ITA 212 (7.6 Africa. The trial suffered severe drought stress at the t/ha) and Bouake 189 (7.2 t/ha). IR 4422-98-3-6.1 and tillering stage and intermittent drought stress at the Table 5. Results of WARDA coordinated varietal trials, upland, moist zone, 1982 Glume Plant Growth Drought discolors- Sheath Grain Yield, height, duration, tolerance, tion. mt, length. Chalkinrss, Variety kglha crn days 0 to 9 0 to 9 0 to 9 1 to7 0 to 9 Short duration DJ 12-539-2. . . . . . . . . . . . . . . . . 3,240 80 120 5 3 1 5 9 IRAT 109 . . . . . . . . . . . . . . . . . . 3,133 91 115 3 3 3 5 9 IRAT 110 . . . . . . . . . . . . . . . . . . 1.656 78 100 1 5 5 5 5 IRAT 144 . . . . . . . . . . . . . . . . . . 2,322 100 107 3 3 1 3 5 RAT146 . . . . . . . . . . . . . . . . . . 1,926 91 i l 5 5 I 3 3 5 ITA117 . . . . . . . . . . . . . . . . . . . . 2.547 87 120 5 1 1 3 1 ITA 235. . . . . . . . . . . . . . . . . . . . 3,101 102 123 1 1 0 3 I M 5 5 . . . . . . . . . . . . . . . . . . . . . . 2,742 10.5 102 3 1 3 5 9 TOx 1011-4-2 . . . . . . . . . . . . . . . 2,354 84 103 5 1 5 3 5 TOx 718-1-23 . . . . . . . . . . . . . . . 2 947 95 125 1 3 0 3 0 ImA 118 (check), . . . . . . . . . . . . 3,015 95 120 3 1 3 3 5 Mean . . . . . . . . . . . . . . . . . . . . . 2,633 LSD (5%). . . . . . . . . . . . . . . . . 519.5 c.v.,%. - - . .. . . . . . . . . . . 13.69 Medium duration SEL E A T 194/1/2. . . . . . . . . . . 3,453 7 07 135 3 1 3 5 I IRAT 104 . . . . . . . . . . . . . . . . . . 3,339 120 I . , ~ F. 1 0 7 9 E A T 156 . . . . . . . . . . . . . . . . . . 3,242 106 130 3 1 I 5- n" IRAT 170 . . . . . . . . . . . . . . . . . . 3,141 101 130 5 1 3 7 1 IRATI38 . . . . . . . . . . . . . . . . . . 3,008 104 125 5 1 1 5 5 ITA 162.. . . . . . . . . . . . . . . . . . . 2,910 IRAT 132 . . . . . . . . . . . . . . . . . . 2.694 IRAT 168 . . . . . . . . . . . . . . . . . . 2,674 ITA 141 (check). . . . . . . . . . . . . 2,469 E A T 169 . . . . . . . . . . . . . . . . . . 2,455 IRAT136 . . . . . . . . . . . . . . . . . . 2,376 c 22 . . . . . . . . . . . . . . . . . . . . . . . 2,261 D J 11-509 . . . . . . . . . . . . . . . . . . 1,940 ITA 256. . . . . . . . . . . . . . . . . . . . 1,865 R 9-1-6-1-3-1-1. . . . . . . . . . . . . . 585 Mean . . . . . . . . . . . . . . . . . . . . . 2,561 LSD (5%) . . . . . . . . . . . . . . . . . 515.5 C.V.,% . . . . . . . . . . . . . . . . . . . 14.08 Note: The rating scales for drought tolerance, glume discoloration, sheath rot, grain length and grain chalkiness are adapted from IRRI, Standard Evaluation System for Rice, International Rice Testing Program, Second Edition. 10 Cereals Table 6 . Results of WARDA coordinated varietal trials . moist zone .i rrigated . 1982 Plant Growth Grain Yield. height. duration. Lodging. length. Chalkiness. Variety kg/ha crn days I t 0 9 1t o 7 0 to 9 Short duration TOs 103. . . . . . . . . . . . . . . . . . . . . . . . . . .. 5. 974 90 BR 24-2-1 . . . . . . . . . . . . . . . . . . . . . . . . .. 5. 936 90 IET6056 . . . . . . . . . . . . . . . . . . . . . . . . . . .5 . 827 117 TOx 516-19 SLR . . . . . . . . . . . . . . . . . . . ..5 .8 ‘24 104 IET4506 . . . . . . . . . . . . . . . . . . . . . . . . . .5..7 07 100 IET3137 . . . . . . . . . . . . . . . . . . . . . . . . . .4.. 657 87 IR 36 (check) . . . . . . . . . . . . . . . . . . . . . .. 4.2 47 99 BR 508.B.2.9 . . . . . . . . . . . . . . . . . . . . . . .5 94 110 Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 . 505 LSD. .( 5%.) . . . . . . . . . . . . . . . . . . . . . . . . .8 9 1.4 C.V % . . . . . . . . . . . . . . . . . . . . . . . . . . . .9. 6 Medium duration IR 4422-98-2-6-1. . . . . . . . . . . . . . . . . . . . . 8,4 50 118 ITA212 . . . . . . . . . . . . . . . . . . . . . . . . . . .7. , 5 84 103 Bouake 189 . . . . . . . . . . . . . . . . . . . . . . . 7. . 178 115 Nigersail . . . . . . . . . . . . . . . . . . . . . . . . .. 6.9 20 115 ITA123 . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 . 865 106 R 2360~9~8X. . . . . . . . . . . . . . . . . . . . . ..6 .6 11 120 BW 248-1 . . . . . . . . . . . . . . . . . . . . . . . ..6 .5 84 136 Farox 18RA . . . . . . . . . . . . . . . . . . . . . . . .6.4 17 116 ITA 245 . . . . . . . . . . . . . . . . . . . . . . . . . . ..6 . 386 109 BR 168-2B-23 . . . . . . . . . . . . . . . . . . . . . .6 .3 19 101 ITA 231 . . . . . . . . . . . . . . . . . . . . IR 2071-586~5-6-(3I R 42) . . . . . . . . . . . . BR 13.47.3 . . . . . . . . . . . . . . . . . . . . . . . . .5 ,5 39 132 TOs 103 (check). . . . . . . . . . . . . . . . . . . .5. 342 78 IR 9782-144-3-3-3. . . . . . . . . . . . . . . . . . . . 3. 822 83 Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . .6..4 15 LSD 5 . . . . . . . . . . . . . . . . . . . . . . ..8 68.5 reproductive s tage. Leaf and neck blast were soil stresses were insignificant . Thirty-four entries minimal . Sheath rot and glume discoloration were were selected for vigor. p lant height. growth moderate . Panicle exertion and grain filling were duration. resistance to lodging. panicle characteris- observed t o be poor in many entries because of tics and grain type . Those selections will be further drought stress . Twenty-eight entries were selected evaluated and used in the breeding program . for drought tolerance and recovery. growth duration. In t e rna t iona l r ice yield nursery. ve ry ea r ly panicle exertion. grain filling and resistance to dirty du ra t ion (IRYN VE 82) . This nursery consisted of panicle syndrome . These selections will be further 27 entries from national breeding programs in China. evaluated in the breeding program . India. Sri Lanka and Taiwan and from IRRI. WARDA ini t ial eva lua t ion t e s t , i r r iga ted . This including one international check. IR 50 . The local trial was originally composed of 252 entries from the check was TOs 78. a selection from 1R 269.26.3.3.3 . IR IRTP. IITA and the All-India Coordinated Rice 50 gave the highest yield (6.8 t/ha). as shown in Table Improvement Program and a few entries from 7. IR 9752-71-3-2( 6.4 t/ha) and BG 276-5 (6.3 t/ha) were national breeding programs in Africa. Asia and Latin second and third in yield . IK 50. IR 9752.71.3.2. BG America . Of these entries 32 were destroyed by the 276-5 and IR 9729-67-3 were among the best yielders in Plant Quarantine Station a t Ibadan for reasons of the 1981 IRYN very early trials in 17 Asian and seed health . Insect and disease pressure as well as African countries . BG 276-5 and 367-7 had short. bold. Table 7 . Performance of selected entries in international rice yield nurseries. irrigated. IITA. 1982 Plant Growth Yield Grain Yield. height. duration. perday. length. Chalkiness. Variety kg/ha cm days kg/ha 1 to 7 0 t.u 9 Very early duration 1R 50 (international check) . . . . . . . . . . . . .6 .839 93 102 67 3 I IR 9752.71.3.1 . . . . . . . . . . . . . . . . . . . . . . . . .6 .448 82 100 64 3 1 BG 276.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 .275 105 109 58 7 9 RC 367.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 .193 107 101 61 7 9 HPU741 . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.,8 89 94 96 61 3 1 Kaohsiung Sen Yu 252 . . . . . . . . . . . . . . . . . 5. 544 109 112 50 3 1 1R 19743.46.2.3.3.2 . . . . . . . . . . . . . . . . . . . . . 5..368 96 93 58 3 1 ZHU-XI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 . 354 81 87 62 TOs 78 (local check) . . . . . . . . . . . . . . . . . .. 4. 916 132 125 39 Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.. 899 LSD (5%) . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 .305.9 C.V.. %, . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 6.31 Early duration Kaohsiung Sen 7 . . . . . . . . . . . . . . . . . . . .. 5.9 57 98 118 51 1 UPR 82.1.7 . . . . . . . . . . . . . . . . . . . . . . . . . .5 .467 96 115 48 3 IR 21015.80.3.3.1.2 . . . . . . . . . . . . . . . . . . . ..5 , 181 R 13429-19ti-I . . . . . . . . . . . . . . . . . . . . . . ..5 ,1 76 Tainung Sen 12 . . . . . . . . . . . . . . . . . . . . . ..5 . 115 TOs 103 (local check) . . . . . . . . . . . . . . . . .. 5. 135 PK 95.29.2.1.1.2 . . . . . . . . . . . . . . . . . . . . . .. 4,9 59 Chianung Sen Yu 13 . . . . . . . . . . . . . . . . . .4,9 57 IR 36 (international check) . . . . . . . . . . . .. 4, 579 Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 ,2 82 LSD (5%) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 890.7 C.V., %, . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..1 2 .72 Medium duration LR 54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..7 ,2 35 IR 19670.263.3.2.2.1 . . . . . . . . . . . . . . . . . . . .6 ,8 75 BG 400.1. . . . . . . . . . . . . . . . . . . . . . . . . . . ..6 ,8 14 IR 22082-41-2 . . . . . . . . . . . . . . . . . . . . . . . .6 ,5 36 RP 1017.76.1.3.2 . . . . . . . . . . . . . . . . . . . . . .. 6,5 28 ITA 212 (local check) . . . . . . . . . . . . . . . . . 6. ,4 04 R 2489R.PN.1.76.8 . . . . . . . . . . . . . . . . . . . ..6 ,3 66 RP 1082.24.1.1.1. . . . . . . . . . . . . . . . . . . . . ..6 ,3 62 IR 13540-56-3-2~1. . . . . . . . . . . . . . . . . . . . . .6 .269 MR24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1R 42 (international check) . . . . . . . . . . . . Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5. 8 67 LSD (5%.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 825.59 C.V .. "I.n. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8. . 59 chalky grains. while IK 50. HPU 741 and IR 9752-71-3- IRRI. including onc international check. M 36 . The 1 had long translucent grains. Four varieties (IR 50. highest yielder was Kaohsiung Sen-7 from Taiwan. IR 9752.71.3.2. HPU 741 and RP 1674-4038-78-3)t hat followed by UPR 82-1-7 from India. both of which are had very short growth duration (91 to 102 days) and dwarf varieties with growth duration of about 120 good grain quality would be worth testing in an irrigated double cropping system. days (Table 7) . TOs 103. the local check. performed better than IR 3~ 6~ . However .. all the hi"ch v" irlders in ~~ In t e rna t iona l r ice yield nursery . ea r ly du ra - this trial were about one week longer in maturity t ion (IRYN E 82) . This nursery consisted of 27 than IR 36 . None of the entries in this experiment en t r ies from na t iona l breeding programs in produced significantly higher yields than the local Bangladesh. India. Pakistan and Taiwan and from check . 1R 9828.91.2.3. which had excellent grain 12 Cereals quality, was also one of the high yielders in the 1981 ITA 230 and ITA 232. The nominations for the moist IRYN early trials a t several locations in Asia and zone, irrigated, short and medium duration trials West Africa. were ITA 212, ITA 123, TOx 514-16-101-1a nd TOx 504- I n t e r n a t i o n a l r i ce yield nu r se ry , m e d i u m 21-120-B-B. Under dryland conditions ITA 116 and du ra t ion (IRYN M 82). The 27 entries in this nur- 117 were found to be average performers, with yields sery were nominated by national hreeding programs of 2.5 to 3.5 tons a t several locations. ITA 230, the best in Bangladesh, Brazil, India, Indonesia, Malaysia, performer, yielded 6.1 t /ha and had a growthduration Sri Lanka and Taiwan and by IRRI. The inter- of 134 days in the Sahel, irrigated, medium duration national check was 1R 42, and the local check was trial, which was conducted a t six locations. The next ITA 212 (Table 7). IR 54 gave the highest yield (7.2 best varieties were TR 3273.P239-2 and IR 42. In the tiha), followed by IK. 19670-263-3-2-2-1( 6.9 t /ha) and moist zone, irrigated, medium duration trial, which RG 400.1 (6.8 t/ha). ITA 212ranked sixth in yield, with was conducted a t 12 locations, ITA 212, with an 6.4 t/ha. while IR 42 produced 6.2 t /ha. Of the top 10 average yield of 4.9 t/ha, was second to IR 4422-98-3-6- entries in yield, IR 54, IR 22082-41-2 and ITA 212 had 1 , which produced an average yield of 5 t/ha. At the the best grain quality. 1R 54 was among the top five Suakoko station, ITA 212 and IK 42 were found to entries for yield in 20 Asian and African locations in have some tolerance to iron toxicity. the 1981 IKYN medium duration trials. In t e rna t iona l upland r ice yield nursery . Six I n t e r n a t i o n a l r i c e o b s e r v a t i o n a l n u r s e r y IITA lines, ITA 116, 117, 118, 162, 225 and 235, wcre (IRON 1982). This nursery had 350 entries from 20 nominated for this trial. According to preliminary countries and horn IRRI, IITA and CIAT. Growth reports from 10 locations in Asia and Africa, the duration ranged from early (less than 120 days) to mean yields of IITA lines ranged from 1.6 to 2 t , and mcdium/late (more than 120 days). The varieties used ITA 162 was the best performer. ITA 116,117,118,225, as local checks were ITA 212, ITA 123 and TOs 103. and 235 were found to be resistant to leaf blast. Insect and disease pressure and soil stresses were I n t e r n a t i o n a l u p l a n d r i c e o b s e r v a t i o n a l minimal. Sixty-five entries were selected for vigor, nursery . Fifteen IITA lines, ITA 116. 117. 118, 119, plant height, growth duration, resistance to lodging, 141, 142, 158, 162, 164, 173, 175, 183. 186, 225 and 235, panicle characteris t ics and grain type. These were among the 104 entries evaluated in this nursery. sclect,ions will he further evaluated and used in the According to a preliminary report from 17 locations breeding program. in Africa and Asia, severalIITA lines performed well. All the trials for which results are presented in the The following wcre rated good for both tolerance to foregoing paragraphs were conducted a t IITA in and recovery fromdrought: IR 13240-10-1.I K 3794-9-2- 1982. The experiments discussed in the following 3, and ITA 235, 164, 173. 175, 183 and 186. Of these paragraphs were carried out i n 1981 a t other entries, the following wcre rated good for phenotypic locations. acceptability: IR 3794-9-2-3,I TA 235, ITA 164, ITA 175 and ITA 183. Entries rated good for leaf blast resist- WARDA in i t ia l eva lua t ion t e s t , upland. A total ance were ITA 117, 225, 142. 175, 118,235 and 164. of 49 entries from IITA's upland rice hreeding program were nominated for WARDA's upland IITAIIRATINCRI upland r ice t r ial . The objec- initial evaluation trials, which were conducted a t 11 tive of this trial was to evaluate the agronomic sites. O f t h e 174 entries, ITA 233 gave the highest characteristics, grain quality and tolerance t o average yield of 371 g/m2. Of the top 25 entries, 13 upland stresses in Africa of upland cultivars selected came from IRAT, 5 from IITA, 4 from IRRI and 3 from from the breeding programs of IITA, EtAT and NCRI. other sources. Four outstanding IITA lines were ITA The trial was laid out in ;i randomized block design, 178. 230,231 and 130. with four replications and a plot size of 5 m x 3 m. N, WARDA in i t ia l eva lua t ion t e s t , i r r igated. This P and K were applied each a t the rate of 60 kg/ha in trial, which included 216 entries, was conducted a t 11 the form of 15: 15: 15 compound fertilizer before direct sites. There were 14 nominations from IITA's lowland seeding with spacing of 3 cm x 15 cm. Seven weeks rice breeding program. IR 14632-22-3g ave the highest after seeding 30 kg/ha N was applied in the form of average yield of 511 g/m2,f ollowed by IR 15529-256-1 urea. There was severe drought stress during the and 1K 9784-142-1-3-3.T he best performers among the tillering stage and medium stress a t the reproductive IITA lines were ITA 252 (434 g/mZ),f ollowed by TTA stage. 250 (433 g/m2) and ITA 240 (416 g/m2). IRAT 133 and 109 produced higher yields than the other test entries hut had highly chalky endosperm WARDA coord ina t ed v a r i e t a l t r ia l s . IITA (Table 8). Generally, endosperm chalkiness was participated in t he coordinated varietal t r ia l noticeable in all IRAT varieties and in DJ 12-539-2, network of WARDA by nominating entries from the FAROM 4-2 and FAROX 211-8-2-3. Among the IITA Institute's breeding program. The entries nominated varieties, TOx 1011-4-1 and ITA 150 are probable for the upland trials were ITA 116 and 117; those candidates for trials in the sub-Sahel and savanna nominated for the Sahel, irrigated, short and medium ecologies because of their growth duration (about duration trials were TOx 504-21-120-B-B,T Os 4688, 100 days). Varieties from IITA were of medium Cereals 13 duration (120 to 130 days), and those from NCRI were day-old seedlings of the test entries were transplan- Intermediate to tall in stature. lodgu ed to some deg- ree ted in a single row (15 hills), with two seedlings per and produced lower yields.-hung Zan hill, spacing of 25 cm x 25 cm and two replications. OS 6 (susceptible) and Iguape cateto (resistant) were also transplanted after every fifteenth test entry. Entomology Between 15 and 20 days after transplanting of the test entries, another hatch of approximately 2,000 Stalk-Eyed Fly insects was released inside the screenhouse t.o ensure The stalk-eyed fly, which is indigenous to Africa, is a that the population would be sufficient. After this serious pest of rice on this continent. Although three second release, no more releases were made since the different species of stalk-eyed flies are infesting rice, population in the screenhouse was then able to the species Diopsis thoracica West is predominant, maintain itself. constituting about 900/, of the population. Border rows were removed 70 days after planting Success in breeding for resistance to this insect (30 days after the test entries were transplanted). By depends largely on the development of reliable that time a new generation of insects had emerged screening techniques. A simple method was devel- from the border rows, and the test entries were ready oped a t IITA for screening germplasm collections for infestation. New border rows were planted within and breeding materials systematically in the screen- 3 to 4 days. D. thoracica infestation was measured on house. High populations of stalk-eyed fly can be test entries 45 days after transplanting. maintained inside the screenhouse, the layout of Test entries were removed 65 days after planting, which is shown in Figure 1, and screening can be and another batch of test materials was transplanted done throughout the year in the manner described in within a couple of days. The planting schedule of the following paragraphs. horder rows and test entries helped D. thoracica Five border rows of 21-day-old seedlings of the adults emerging fkom border rows to infest entries variety Suakoko 8 were planted 40 days before test and to move from test entries back to border rows. materials. Suakoko 8 was selected because previous A total of 988 rice cultivars (937 of 0. sativa and 51 studies had shown that the stalk-eyed fly is more of 0. glaberrima) were screened for resistance to attracted t o i t for egg laying. Moreover, t he stalk-eyed fly in batches from March to November development rate of the maggots on this variety is 1982. The cultivars, of which 73.89"/, were from lower than on others. About 2,500 D. thoracica were Africa, came from 39 rice growing countries around released 20 days after the border rows were planted. the world. Infestation ranged from 1.25 to 66.67'y0, Forty days after planting of the border rows, 21- whereas under natural field conditions, the maxi- Table 8. Performance of cultivars from IITA, IRAT and NCRI in an upland rice trial, 1982 Plant Grrlwth Endosperm Sheath Grain dis- Drought Yield hei-ght,. duration. chalkiness. rot. coloration. tolerance. Variety kg/ha crn days Oto9 0 to 9 0 to9 0 to 9 IRAT 133 . . . . . . . . . . . . . . . . . . . . . . . 4.565 102 100 9 5 3 5 ITA 117 . . . . . . . . . . . . . . . . . . . . . . . 3,721 110 116 1 TOx 1011-4-1. . . . . . . . . . . . . . . . . . . . 3,707 94 100 I ITA 118 . . . . . . . . . . . . . . . . . . . . . . . . 3,597 119 119 5 3 3 3 D J 12-539-2.. . . . . . . . . . . . . . . . . . . . . 3,385 89 112 9 1 3 3 ITA 150 . . . . . . . . . . . . . . . . . . . . . . . . 3,272 120 98 1 0 1 3 ITA 236 . . . . . . . . . . . . . . . . . . . . . . . . 3,159 126 115 1 0 3 1 FAROX 210-19-4-14.. . . . . . . . . . . . . . 2.676 130 I16 5 1 5 5 IR 5931~110-1. . . . . . . . . . . . . . . . . . . . 2,511 113 121 5 IRAT 138 . . . . . . . . . . . . . . . . . . . . . . . 2.233 117 123 5 Mean . . . . . . . . . . . . . . . . . . . . . . . . . . 2,790 LSD (5%). . . . . . . . . . . . . . . . . . . . . . . 728.46 C.V.. O/,. . . . . . . . . . . . . . . . . . . . . . . . . 18.41 - 24 rn em. FOOT P A T H I I F O O T P A T H I BB order row -.-Test entry xxx Susceptible A Resistant check Figure 1. T,ayout of the procedure hy which rice varietiesllines are screened in the screenhouse fc)r resistance to stalk-eyed Hy, Ditipsis thorncica. mum infestation by stalk-eyed fly is about 15"/,. resistance to these insects has shown promise in Fifty-seven cultivars (37 of 0. sativa and 20 of 0. curtailing losses. The use of such varieties against glaberrima) from 13 countries were found to have less storage moth (Sitotroga cerealella) infestation would than 10% infestation. Of the 57 promising cultivars undoubtedly reduce postharvest losses a t no selected, only 8 were improved varietiesllines; thc additional cost and with no risk from chemical rest were germplasm collections. The highest residues. Experiments were conducted a t IITA to test frequency of selected materials (39.2%,) was found TITA advanced and promising lines, recommendcd among the 0. glaberrima collection, compared with cultivars and farmers' varieties for resistance to the only 3.9%, among the 0.s atiua entries. These selected storage moth under short- and long-term storage and materials will he retested for final confirmation of t o identify physical properties of thc grains that their resistance. Cultivars with less than 4%) affect the resistance of these varieties. infestation are listed in Tahle 9. M.S. A l u m In short-term resistance screening, eleven rice cultivars were tested. Seven grams of grain for each Storage Moth of three replicates were infested with 50 eggs of S. cerealella in a no-choice test. The grain was placed in Insects are reported t o he the main cause of crop glass vials i n an incubator maintained a t 25'C and 70 Iosses in storage. 'The use of rice va r i e t~esw ith to 75'/, relative h u m d ~ t yu nder a 12-hr-hghtl12-hr- Table 9. Best 20 cultivars selected for resistance t o Table 10. Susceptibility of rice varieties to storage stalk-eyed fly in a mass screenin-a test. moth. IITA. 1982 IITA, 1982 - Percent Index of We-i~ ht Designation and Infestu- Cultivar emergence susceptibility loss. g IITA acc. no. Source tion. ' j / , IR 5 . . . . . . . . . . . . . . 2.0 a 0.86 a 0.0i a TOs 5827. . . . . . . . . . . . . . Liberia 1.2 Moroberekan . . . . . . TOs 3213. . . . . . . . . . . . . . . . . . Ivory Coast 1.8 Lac 23 red. . . . . . . . . TOs 285. . . . . . . . . . . . . . . . . . . United States 1.8 Ceylon 49 . . . . . . . . . 13.0 bc 5.12 br 010a TOs 372. . . . . . . . . . . . . . . . . . . Indonesia Lac 23 white. . . . . . . 15.0 bcd 6.53 brdc 0 22 a TOs 3212.. . . . . . . . . . . . . . . . . Ivory Coast Kolon Kalan . . . . . . 15.5 bed 6.67 cde 0.37 ab TOs 5792. . . . . . . . . . . . . . . . . . 1,iberia CH 128.. . . . . . . . . . . 16.5 bcd 6.76 cde 0.32 ah TOx 916-6-1-101-2.. . . . . . . . . . IlTA TOx 86-1-3-1. . . . . . . 19.5 bcde 7.77 dcfg 0.53 h Tog 6390 . . . . . . . . . . . . . . . . . Libcria TOx 494-5-1-2 . . . . . . 23.5 cde 8.21 efg 1.63 e TOs 272. . . . . . . . . . . . . . . . . . . United States OS6 . . . . . . . . . . . . . . 31.0 de 9.27 fg 0.84 c TOs 5677. . . . . . . . . . . . . . . . . . Nigeria IllAT 13. . . . . . . . . . . 35.5 e 9.85 g 1.24 d TBD* . . . . . . . . . . . . . 7.05 2.47 0.31 ITA 121.. . . . . . . . . . . . . . . . . . TTTA TOs 5267. . . . . . . . . . . . . . . . . . Ivory Coast Nute: Mrans followed by the same letters in the same column are TOs 657. . . . . . . . . . . . . . . . . . . Unit.ed States not significantly different from carh other. *Far ernergmce and susceptibility, differences are significant a t TOs 373.. . . . . . . . . . . . . . . . . . Indonesia the 1% levcl and fur weight loss a t the 5'):, level. X.2.D.T . . . . . . . . . . . . . . . . . . Vietnam TOx 9'36-153-5-3~3. .. . . . . . . . . IITA T,1, O s 663. . . . . . . . . . . . . . . . . . . Nigeria Table 11. Effect on rice varieties of infestation by 0s 5734. . . . . . . . . . . . . . . . . . Liberia storage moth during four months of TOx 891-212-2-102~1..1. . . . . . IITA storag- e, IITA, 1982 TOE 6481 . . . . . . . . . . . . . . . . . Liberia Weight loss Damage Cultivar Mean, D/, Log 10x Mean, '7; Log 10x Ceylon 49. . . . . 0.33 0.48 a 1.7 0.74 a dark cycle. The exueriment was terminated after 45 IR 5 . . . . . . . . . . 0.71 0.84 ab 3.2 1.02 ab days. Moroberekan . 2.08 1.21 r X X 1.37 bc Four varieties selected during the short-term Lac 23 red . . . . 3 01 1 . 4 3 ~ 13.2 160c screening were further tested in a long-term LSD (5%). . . . 0 56 0.52 screening test. In this no-choice test, 260 g of grain Note: Means followed by the same letters in the same column are per replicate of each test variety were infested with not significantly different from each other. 50 newly emerged male and female adults of S. cerealella in equal ratios. The grain was stored in cloth hags under room conditions for four months. Although Moroberekan was more resistant than Two indices of susceptibility were used in the Ceylon 49 t o 5'. cerealella damage under short-term short-term screening test. The first is based on the storage, i t was more susceptible under long-term population size the variety will permit S. cerealella to storage. The most susceptible rice varieties, IRAT 13, reach under a given set of physical conditions, OS 6, TOx 494-5-1-2 and TOx 86-1-3-1, were found to starting with a fixed number of eggs. This index is have a high percentage of grains with open husks expressed as Log F,/D, where F is the number of and, with the exception of OS 6, had a common insect progeny in the first filial generation for a parent , 63-83. A s indicated by t h e correlation development period D. The second index is the coefficients in Figure 2, there were positive, highly percentage g ra in weight loss. The index of significant correlations between the number of susceptibility for the long-term screening test was grains with open husks and the number of F1 insect based on the percentage loss in weighted means. In progeny and between the number of grains with gaps determining the influence of the physical properties and loss in grain weight caused by S. cerealella of the grain on resistance to S. cerealella damage, 100 damage. grains per replicate ofthe samples tested in the short- The variation among rice varieties in their term screening test were examined under t he reaction to S. cerealella and in grain weight loss microscope for open husks, and correlation analysis indicate that they have varying levels of resistance. was done on data obtained along with that on the This study suggests that thedifferential reactions of number of F1 insect emergents per variety. these rice varieties are due to a physical resistance Significant varietal differences were found in the base, namely husk tightness, which apparently is number of F1 insect progeny and loss in grain weight genetically controlled. Further investigations into (Tables 10 and 11). IR 5 was the most resistant to S. t h e heri tabi l i ty of this resis tance base and cerealella infestation under short-term storage, and identification of other resistance mechanisms are IRAT 13 was least resistant. Under long-term required. If the resistance base is found to be storage, Ceylon 49 did slightly better than IR 5, hut genetically controlled, then IR 5 and Ceylon 49 could the difference between them was not significant. serve as resistance sources to be used by breeders i n 16 Cereals Table 12. Results of screening for blast resistance, IITA, 1982 Total no. Percentage of entries of entries tested resistant CIAT . . . . . . . . . . . . . . . . . . . . . 90 84.4 IRAT . . . . . . . . . . . . . . . . . . . . . 14 TITA . . . . . . . . . . . . . . . . . . . . . 160 IRK1 (IRRN 81) . . . . . . . . . . 155 (IRBN 82) . . . . . . . . . . . . 295 Table 13. Entries in a blast screening trial with resistance and high yield potential, IITA, 1982 Entry number Entry number and pedigree and pedigree CIAT IRRl 11295 P 2015 F4-66-5-lB IR 1905-$1~3-1 1R 2793-80-1 IR 9752~71-:1-2 IR 13423-10-3-3 TR 15314-43-2-3-3 IR 17488~2-32 incidence BG 367-4 of grains with gaps in rice hulk BR 319-1-HR 12 Figure 2. Relationship between the incidence of grains with open husks and the emergence of S. cerealella adults and grain weight loss, IITA, 1982. IITA IRA T crosses. In addit~oni,d entifying the source of open ITA 120 TOx 502-25118-1-1 IKAT 13" husks will guidericc breeders in selecting parents for TTA 132 TOx 340-1-5~1 IRAT 118 c r o s s e s . D. Akibo-Betts ITA 135 TOx 378-1-6-1 IRAT 119 1TA 150 TOx 502-41-1-1 IRAT 122 ITA 162 TOx 503-7-11 6-1 IRAT 125 Pathology ITA 235 TOx 1786-1~ 91-8 IRAT 126 ITA 241 TOx 711~3-201 During 1982 emphasis was placed on developing resistance to blast and rice yellow mottle (RYMV) "Pedigreen ot available. diseases. The former is the most widespread disease of both upland and irrigated rice in Africa, and the A total of 714 entries from four sources-CIAT, latter poses a potential threat in irrigated rice IRAT, IITA and IRXI-were tested in the upland paddies. The major ohjective was to test fixed lines screening nursery for blast resistance. The disease was severe and almost killed the susceptible lines. The percentages of entries found to be resistant are ~ ~~~ yield loss caused hy RYMV disease were carried out listed in Table 12. The data clearly indicate that a in the screenhouse. Preliminary efforts were also higher percentage of the entries from CTAT and IITA made to select material showing resistance to panicle were resistant under the upland testing conditions of discoloration and leaf scald diseases. IITA. Entries of the advanced lines known to have good yield potential and blast resistance are listed in Blast Table 13. One hundred and fifty hreeding lines were tested Blast resistance was studied in the field under upland conditions. Seeds of test entries and those of a for resistance to drought under upland conditions. susceptihle spreader were sown a t the rate of 10 g/2-m Natural infection by blast in this trial killed the row. To initiate infection hlast infected leaves were susceptible lines. Seventy-one entries with a score of spread on the susceptible spreader lines, which 1 to 2 were selected for further evaluation of their consisted of a mixture of blast susceptible varieties. yield and agronomic characters and for confirmation Nitrogen was applied at a rate of 120 kg/ha in split of blast resistance (Table 14). applications to encourage high disease pressure. The entries tested were visually scored on a scale of Rice Yellow Mottle Virus O to 9 (the standard evaluation system for rice), with 0 Three hundred and fort,y varieties from diverse representing high resistance and 9 extreme sources were screened for rice yellow mottle virus susceptibility. resistance under upland conditions in a screenhouse. Cereals 17 Table 14. Selections with resistance t o blast, IITA, The test entries were inoculated mechanically 20 1982 days after germination. Twenty-five days after No inoculation, lines that seemed healthy were scored as ~ . o~ f lines selected Cross (1) tolerant (plants look green with very little or no TOx 714.. . . 8 ROK 5 x IR 937-55-3 mottling, normal tillering and flonrering but have TOx752 . . . 9 OS 6 x Moroherekan serologically detectable virus); (2) susceptible but TOx 891. . . . 10 IR 8230-12-1 x LAC 23 (white) able to recover; and (3) highly susceptihlc. Table 15 TOx897 . . . . 8 IR 8 x LAC 23 (white) lists the sources and types of material and gives their TOx 906. . . . 10 4445 x 0s 6 overall performance. TOx908 . . . 16 4445 x IAC 25 One hundred and fifty-two entries with tolerance TOx 936. . . . 10 1R 1529-430-3 x lruape catcto t o the local strain of RYMV were tested serologically for the presence of virus. All entries tested reacted Table 15. Results of screening for rice yellow mottle positively, confirming the presence of the virus. virus. IITA. 1982 Tolerant entries with high yield potential are list,ed Total ntl in Table 16. Most of the entries listed in the table are of entries Percentage Percentage suited to upland conditions. Note also that in most t~sted tolerant susceptible cases tolerance toRYMV occurs in crosses involving Asia.. . . . . . . . . . . . . . . . . 28 21.4 78.6 LAC 23, Moroberekan, OS 6 and 63-83. CTAT . . . . . . . . . . . . . . . . . $7 0 100.0 Analysis of t he material reacting t o RYMV IITA . . . . . . . . . . . . . . . . . 67 61.2 38.8 indicated that all the glaberrima varieties tested T O s . . . . . . . . . . . . . . . . . . 92 83.7 16.3 were tolerant to RYMV (Figure 3). Although most of TOe . . . . . . . . . . . . . . . . . . 23 100.0 0 the susceptihle plants recovered from the early symptom of t he disease (yellowing), they were Table 16. Entries in a rice yellow mottle virus severely stunted; their flowering was very much screening trial with high resistance and delayed; and their grains were chaffy and discolored. vield ootential. IITA. 1982 One hundred and fifty plants of each of two cultivars, Pedigree Cross one tolerant (OS 6) and another susceptible (BG 90-2) 1TA 116 TOx $ 6 ~ 1 ~ 3 ~ 1 63-83 x 773 A1-36-2-1 to RYMV, were grown in three replications, with 50 ITA 117 TOx 356-1-1-1 13A-18-3-1-3x TOx 7 ~ 4 ~ 2 ~ 5 ~ 2p lants in each replicate. The trial was carried out ITA 118 TOx 475-1-1-1 TOx 7-4-2-5-1 x 6 3 ~ 8 3 under upland conditions 20 days after germination. ITA 119 TOx 490-Rl08-1-1 LAC 23 (red) x IET 1444, The plants were inoculated mechanically with TOx 7-4-2-3-2. TOx 7-3-2-3-2 RYMV inoculum, and proper controls, replicated as ITA 120'" TOx 502-25-118.1~1 6 3 ~ 8 3x ROK 1, SE 3636, above, were maintained. The plants were allowed to TOx 7-3-2-1-1-1-1 flower, and the yield of 75 randomly selected plants ITA 135a TOx 378-6-1 63-8:3 x IR 26 was estimated for the two varieties. Inoculation ITA 141 TOx 490~125-4-1 LAC 23 (red) x IET 1444, TOX 7-4-2-3.2, TOX 7~3-2-3-2 reduced the yield of OS 6 plants from 17.64 g/plant for TTA 142 TOx 494-5-1-2 6 3 ~ 8 3x Iguapc Cateto healthy ones t o 14.36 g. Sterility was increased in ITA 150" TOx 502-41-1-1 63-83 x ROK 1, SE 3636, these plants from 17.08 to 31.44%,. Although the TOx 7 ~ 3 ~ 2 ~ 1 - 1 - 1 ~ 1 reduction in yield was not significant a t the 10/, level, ITA 162" TOx 503-7.116~1 Moroherekan x ROK 1, the increase in sterility was. In the susceptible Suakoko 8, TOx 7-3-2-1-1-1-1 variety, inoculation reduced yield from 9.84 g/plant ITA 182 TOx 516-20-102-5-1 Moroberekan x Juma 1. to 0.64 g and increased sterility from 45.75 to 73.97%. TOx 7-3-2-3-2,S E 363G Both the yield reduction and increase in sterility ITA 23EIa TOx 1785-19-18 OS 6 DM x OS 6 were significant. Kulu 1R The low yield and high percentage of sterility in 1846-296-3 J P 5 x Y R L 1 IR 2298-PLPR-319- healthy, uninoculated plants of RG 90-2, a variety I-2-I-IB Cica 4 x Kulu that is hred for cultivation on irrigated land, could be attributed to the upland conditions under which the rAlsa resistant to blast. test was carried out. . * Tolerant .> .. ;i. . *. .< .,< -..;*.- , .<. .%< . . .,... Susceptible Panicle Discoloration and Leaf Scald Observation nurseries a t Onne were severely affected by panicle discoloration. Table 1 7 lists four entries from Onne with tolerance to panicle discoloration caused by Acrocylindrium oryzae, Helminlhosporium oryzae and Curvularia lunata. At Ikenne, during the wet season of 1982, naturally occurring leaf scald (Rhynchosporium oryzae) was severe. The breeding G / o b e r M Upland Irrigated (Lowland ) lines shown in Table 18 may he resistant to leaf scald Figure 3. Reaction of entries to rice yellow mottle virus in a but need to he retested for confirmation. screenhouse test. IITA, 1982. I t is clear from the foregoing discussion that Cereals 19 semiarid conditions. IITA's maize agronomist with Table 19. Populations selected for development of SAFGKAD carried out experiments on simple experimental maize varieties agronomic practices that can be used by small scale Population Description Adaptation farmers to conserve soil moisture and improve soil TZSR-W-1.. . . . . . . . . Late white flint Lowland forest management. During 1982 these practices were and savanna tested in farmers' fields. TZSR-Y-1 . . . . . . . . . . Late yellow flint Lowland forest and savanna Genetic La Posta (Pop. 43)". . Late white dent Idowlandf orest Improvement and savanna Population Improvement TZMSR-WD.~ . . . . . Late wbitc dent Midaltitude TZMSR-WF" . . . . . . . Late white flint Midaltitudc The EEC-funded High Yielding Varieties TZUT-W.. . . . . . . . . . Intermed. white Savanna Technology Project has widened the scope of the semiflint population improvement program and much en- TZUT~YC. . . . . . . . . . Intermed. yellow Savanna hanced i t s relations with national programs. semiflint Progeny and variety testing was proposed for 16 sites TZESR-W. . . . . . . . . . Early whitc flint Lowland forest and savanna across Africa, four each in the western, eastern, TZESR-YC . . . . . . . . . Early yellow dent Lowland forest southern and central regions of the continent, during and savanna the second phase of the project. The populations Pool-16 . . . . . . . . . . . . Early whitc dent Lowland forest listed in Table 19 were selected for improvement and and savanna development of experimental variet ies, with aFrum CIMMYT's maize breeding program. emphasis on maize streak virus resistance. hPresentlya mixcd tlint and dent population. A backup unit for each type of maturity and grain =TheS AFCRAD/IITA team in Upper Volta is concentrating on color either exists or will be established in the future improvement of this population. to provide improved germplasm for the populations. In the backup units, multiple resistance to diseases progeny tr ial of TZSR-W-1 and TZSR-Y-1, six and insect pests will be emphasized. Yellow and experimental varieties were formed by combining the white populations with comhined resistance to best 6 to 10 full-sibs from each of the six test downy mildew have also been developed for the areas locations. The test locations were Ferkessedougou infested with this disease, especially in Nigeria and (Ivory Coast), Ikcnne (Nigeria) and Sekou (Benin) Zaire. For each population, a two-year improvement for TZSR-W-1 and Farako-Bi (Upper Volta), cycle is carried out as follows: Ferkessedougou and lkenne for TZSR-Y-1.T hese six, Year 1, season 1-Formation of full-sibs late, streak resistant varieties, two experimental Year 1, season 2-International testing of full-sib varieties each from populations TZR and TZPB, and families in four to six locations two check entries to be supplied by the trial cooperator were combined to form one trial. The Y e a r 2, season 1 Within-family improvement of primary purpose of the trial was to compare the selected families across performance of the streak resistant varieties with locations that of the currently recommended improved maize Year 2, season 2-Half-sib recombination of the varieties, such as TZB and TZPB, in various selected families countries of Africa. A randomized complete block Year 3, season 1--Formation of a new cycle of design with four replications was used; the plots full-sibs consisted of four rows 5 m long with 75 cm x 25 cm spacing. The trial was sent to 24 locations in 17 Following each international full-sib testing, countries. experimental varieties are produced by recom- bination of the best 10 families a t each testing site, For a number of reasons, particularly the differences in planting seasons between countries on along with one based on selected families across all sites. The 10 best families are first recombined in all both sides of the equator, data from only 10 locations (six countries) have so far been received. The level of possible combinations and later by half-sib for seed increase and testing by national programs. streak infection was not high enough a t any of the locations to allow a meaningful evaluation of streak TZSR-W-1 and TZSR-Y-1. Maize streak virus resistance. It is encouraging, however. that in the disease is currently the most widely distributed absence of streak virus (which permitted the economically important disease of maize in Africa. experimental varieties from TZB and TZPB to realize The development of streak resistant varieties is their full yield potential), the yields of the late, streak therefore essential to achieving stable maize resistant varieties were not significantly different production in this region. TZSR-W-1 and TZSR-Y-1 from the yields of TZB and TZPB (Table 20). The are the two main populations from which streak value of the streak resistant varieties is expected to resistant white and yellow grained maize varieties become more obvious under severe streak infection. are heing extracted. Further improvement of TZSR-W-1 and TZSR-Y-1 Based on data from the 1981 international full-sib was carried out in 1982. Of the 250 full-sibs tested for 20 Cereals Tahle 20. Average maize yields in a n international experimental trial of late, streak resistant varieties. 1982 p,cnin Cameroon Ghana Kenya Liberia Nigeria Entry Entries Niaouli Nrui Njumhe Nyankpala Kikamhala Suakoko Ibadan Ikenne Tlorin Samsru mcan Ikenne LSRW 81 . . . 4.380 5,203 5.002 5,348 2,29i 3,172 4,210 6,079 5,473 4,224 4.5:38 FcrkeLSKW 81 . . . . 3.585 5,240 5,277 5.290 2,110 4,044 3.596 4.964 5,446 3,847 4.340 Sekou LSRW 81 . . . . 4.165 5.673 4,5437 6.379 2,583 3.093 4,514 5,327 5,897 4,888 4.703 Ikennc LSRY 81 . . . . 4.016 4,610 5.122 4,993 1,458 4.285 4,393 5,211 5,909 5,075 4,507 Ferke ISRY 81. . . . . 3,797 5,371 5.222 4.820 2,051i 3,605 4,003 4.476 5,898 5.070 4,432 Farakoba LSRY 81 . 4,502 4,158 4.559 4.982 1,586 3,706 4,450 4,895 5,403 5,901 4,414 Mokwa TZB 81. . . . . 4,500 4.857 4,4:36 6.660 2,421 3,589 5,372 5.744 7,646 4,304 4,933 Gusau TZR81. . . . . . 4.649 6,502 4.821 6,984 2,234 3,826 5,227 5,862 7,120 5,667 5,289 Onnc TZPB 81 . . . . . 4.574 5,978 4.443 6,332 1,834 4,063 5.088 6,352 6,124 3,238 4,X21 Suakokc TZPB 81 . . 5,268 5,940 5.148 7,116 2,:i29 3.964 5,028 6,487 6,073 4,513 5,187 Chcck". . . . . . . . . . . . 2.412 5,880 5,563 .5,743 1,790 2.908 3,650 4,807 5,296 5,461 4,351 Cherk . . . . . . . . . . . . 2,890 4.967 4,520 5.295 1,816 3,640 4,451 5.310 5,279 4,304 4,247 Location Mean.. . . . 4,062 5.365 4,885 5,829 2.042 3.658 4,491 5,460 5,964 4,708 LSL) (5'Y"). . . . . . . . . . 753 967 ns 1.761 672 ns 1,276 1.008 1.586 1,705 C.V.,(%,).. . . . . . . . . 13 12 15 21 22 32 20 1:3 18 25 ,'Check varieties a x s elected by t h e nabonal programs and di&r ir,r each lo<,;rtion. each population in the 1981 international progeny the formation of a n experimental variety. An trials, the best 60entries for TZSR-W-Ia nd the best 58 additional variety will be formed based on data from for TLSR-Y-1 were selected hased on their perfor- all locations. These varieties will be made from mance a t all locations. These full-sihs werc selfed remnant seed a t IITA and shipped to CIMMYT, during the 1981 82 irrigation season, and the where they will he included in the international selected S1p rogenies were recombined by the half-sib testing program. The performance of selected method during the first season nf 1982. Both families a t Ikenne is presented in Table 21. operations were carried out under artificially In the streak screening nursery a t IITA, 12 families induced streak pressure in order to improve the with a very high level of streak resistance were quality of streak resistar~cei n t he populations. identified. Plants with a n intermediate to moderate During the second season of 1982. full-sibs were level of resistance were selfed in 48 additional generated among the halflsib progenies of the families. The ears saved from the streak nursery will selected fi~ll-sihs.S election between subfamilies of represent their original families selected on the basis full-sibs and among plants wit,hin a subfamily was of data from the international progeny testing trials based 011 streak resistance, good root and stalk in the next cycle of improvement. As of January 1983, quality. low plant and ear heights and other desirable data had been received from five locations in those agronomic qualities. The full~sibsw ill he sent, t o the trials. The population mean for yield ranged li.(~m4 .9 international progeny trial in 1983. J.M. Fajcmisin to'i .8 t/ha and the coefficient of variation fi.om 11.7 to La P o s t a (popu la t ion 43). CIMMYT maize 17.3'%,.-M. Bjarnason breeders continued recurrent selection f i r yield and TZUT-W and TZUT-Y. The objective of this vther agronomic charactcrs in La I'osta (population research is to develop a population of medium 43) through internatic~natle sting in cooperation wit,h maturity (110 days from planting to maturity) that national programs. They also concentrated on combines the efficient plant t,ype of varieties from the building up streak resistance in the population as Corn Belt of the United States with the disease such and hy backcrossing with TLSR~W-Ia, donor, tolerance of local materials. A base population of for st,reak resistance. TZUT was established a few years ago fi.om crosses For international testing, 250full-sih families were hct,wecn U.S. mat,erials and tropical populations. generated by reciprocal plant to plant crosses. These This population has passed through two cycles of families werc sent as an international progeny recurrent selection to improve general performance testing t,rial to six different countries, where they and uniformity, although grain color was a mixture were tested in a 16 x 16 simple lattice &:sign. The of white and yellow. cooperating countries were Costa Rica, Ivory Coast, During the third season of 1981 8 2 , 38 families Kicaragua. Nigeria. Thailand and Zimbabwe. The selected from 250 half-sihs were selfed to separate same families were planted a t IITA, one replication their S1 progenies into white (TZUT-W) and yellow in a streak screening nursery and another protected (TLUT-Y) populations. TZUT-Y will he improved by fi.om MSV. The hackcross program was cont,inued hy the SAFGKAD project in Upper Volt,& and TZUT-W advancing the first back(:ross generation to F2. will be improved in Nigeria. In the cooperating countries, the best families During the 19X2 rainy season, 242 S1 progenies of (about ten) from each prugeny trial were selected for TZUT-W (derived from 32 half-sib families) were grown in isolation in two replications a t Samaru, to have good levels of resistance to hoth hlight and Nigeria. Bulk seed of all entries were planted as rust. In 1983, 256 entries. including full-sib families males in every third row among the Sl progenies. All and local checks, will be tested in midaltitude S1 progeny rows (female rows) and the undesirable regions of Zambia, Zimbabwe, Cameroon and Nigeria male plants were detasseled before pollen shedding. to improve the population and develop experimental The best plants within selected families were marked varieties from the best full-sib families a t each just hefore maturity, and reselection was done again location and across locations. F.H. Khadr , S.K. before harvest. After harvest the best 182 half%ih Kim and J.M. Fajemisin ears were retained and shelled individu:illy. During Ea r ly ma tu r ing , s t r e a k r e s i s t an t germplasm. the third season of 1982 83, the selected half-sib African maize growers are badly in need of early entries were grown in progeny rows ;it lbadan under maize varieties that are resist,ant to maize streak irrigation t o form full-sib families. These will he virus for planting during the second growing season tested for the first time in international trials in 1983 or for late planting during the first season in areas to further improve the population and t o form where streak incidence is high. In 1977 IITA began a experimental varieties adapted to different crossing program involving TLE 3, TZE 4, TZE 14 and countries. TZE 15 as early parent.s, with TZSR-W and TZSR-Y as At Kamboinsb, Upper Volta. yellow grains of 305 streak resistant parents. After several sr;isons of S1 families were planted in isolation for recom- selfing and selection for agronomic characters and bination. Because of late planting and an early m d t o streak reaction, the best S3 lines were composited in the rains this year, the plants were severely damaged the 1980 second season to form two maize popu- by drought, so selection of recombined ears could not lations, TZESR-W and TZESR~Yw, hich are early and be done effectively. However, 589 ears were selected resistant to streak and produce acceptable yields. and planted during the dry season of 1982-83 for another cycle of recombination. A new cycle of full- In 1981 250 full-sib families of TZESR-W and 250 sib recurrent selection will be initiated during the half-sib families of TZESR-Y were tested at two 1983 season.-F.H. Khadr locat,ions in Nigeria. Seventy-seven fnll-sib families of YZESIZ-W and 44 half'sihfamilies of TZESR~Yw ere TZMSR. This population combines a high level of selected, and remnant seed of these families was resistance to maize streak virus with resistance to P. planted in the third season of 1981 to generate full-sib sorghi (rust) and H. turcicum (hlight), which are the families for testing. At harvest 165 full-sibs fromeach major diseases i n the midaltitude ecology. The of the two populations were finally selected to form population had previously been through one cycle of two separate progeny trials for different locations in selection under rust and blight infestation a t Jos, the 1982 second season. Full-sibs of TZESK-Y were Nigeria (1,200 m above sea level), and one cycle of sent to Nigeria (Ikenne), Cameroon, Upper Volta selection under streak infestation a t Ibadan. Sl lines and Uganda. Full-sibs of TZESR~Ww ere tested a t were grown in progeny rows during the rainy season five locations in Nigeria (Ikenne and Gusau), of 1982 a t Jos. Seedlings were artificially inoculated Cameroon, Tanzania and Zaire. The experimental for leaf blight two weeks after planting. d e s i ~ nw as a 13 x 13 simple lattice with four local At flowering only plants that were reasonably checks. resistant to blight were used in paired crosses among The results of the trials are still coming in. Yield the plants of S1 progeny rows t o form full-sib families. and agronomic data will be used in two ways. First, At maturity most of the progeny rows were ohserved based on data from all sites, up t o one-third of the hest Table 21. Performance of 10 families selected for the formation of an experimental variety, Ikenne 82 43,1982 Yield as Plant Ear Root Progeny Yicld, a percentage Days to height, height, lodging. numher t jha of pop. mean silk cm cm '?:, 99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4 146 55 216 132 3.1 Mean of sclccted families . . . . . . . . . . . . . . . . 7.1 Population mean. . . . . . . . . . . . . . . . . . . . . . . . 5.1 Best check ('EZPB. Onne). . . . . . . . . . . . . . . . . 5.4 22 Cereals performing full-sib families will be selected fnr a t o the four widely grown, recommended varieties new cycle of improvement. Second, experimental (Tahle 22). Populations 2 (TLWD-DMR) and 5 (TIWF- varieties will he created, each consisting of the 10 DMR) expressed a high level of downy mildew best families from each site and from all sites. These resistance and showed promise in yield potential. Of experimental varieties will be assembled in the first even more significance is the fact that t he DMRSR-W and second seasons of 1983 and will be ready for and DMRSR-Y populations, which have resistance to testing in late 1983. downy mildew and streak, performed far better in Following the general population improvement downy mildew resistance and yield than in last year's scheme used in the second season of 1982, these two trials. The yield advantage of thesc populations, populations underwent intrafkmily selection by which is currently about 300% over the presently selfing for agronomic characters and resistance to recommended variet ies under downy mildew streak. During 1983 the selected families will be pressure is expected to be even greater under the recombined, and then the new full-sib families will be combined effects of downy mildew and streak, a generated for further testing. situation that is particularly common in Zaire and IITA will handle the early maturing maize Nigeria. populations with white kernels and SAFGKAD the DMR-W and DMR-Y were merged with the ello ow early populations. During the second season respective DMRSK populations during the 198182 of 1982, Pool-16, an early, white dent pool from irrigation season by utilizing the DMRSR population CIMMYT, was found to he promising in the semiarid (under streak pressure) as the male parent. The zone and underwent intrafamily improvement a t reconstituted populations are still referred t o as TITA t o in t roduce s t r eak res is tance in to i t . DMRSR-W and DMRSR-Y. Population improvement on TZESR-Y was carried out by SAFGRAD/TJTA scientists in Upper Volta. Table 22. Results of a downv mildew resistance and An early maturing, streak resistant gene pool was yield trial, Owo, ~ i g e r i a1,9 82 constructed during 1982 tha t will be used to N...l.l.m...h. pr systematically broaden the genetic base of the Downy mildew of cobs Yield, corresponding TZESR-W and Pool-16. --H.N. Pham Maize entries infection, % per hectare kg/ha Downy mildew a n d s t r e a k res is tance . Since IITAINCKI" downy mildew (Peror~osclerosporas orghi) and streak DMR-W.. . . . . . . . . . . . . . . . . 10 34,000 2,965 coexist in some countries of Africa, i t is important t o D im-Y. . . . . . . . . . . . . . . . . . 12 34,000 3,167 develop maize varieties that have resistance to both. DMRSR-W . . . . . . . . . . . . . . 11 31,000 2,803 DMRSK-Y . . . . . . . . . . . . . . . 7 35,000 3,221 During the year IITA maize breeders evaluated the CIMMYT current cycles of maize populations for downy SW8072 . . . . . . . . . . . . . . . . . 4 30,000 2,623 mildew resistance and yield and further improved SW8075 . . . . . . . . . . . . . . . . . 10 32,000 2,974 those populations for higher levels of resistance to Pop. 2 (TLWD-IIMR). . . . . . 6 34,000 3,380 downy mildew and streak and for better agronomic Pop. 5 (TTWD~DMR.) . . . . . . 5 33,000 2,904 qualities. IIT A A downy mildew resistance and yield trial was T B . . . . . . . . . . . . . . . . . . . 79 6,000 680 carried out that included 12 maize entries: two TZB.. . . . . . . . . . . . . . . . . . . . 66 10,000 1,124 r experimental varieties synthesized from the best 10 I. Z SR-Y-1 . . . . . . . . . . . . . . . . 69 9,000 1,041 lines in each of the populations DMK-W and UMR-Y, IAR&T" Western Yellow. . . . . . . . . . . 85 5,000 579 bulk seed of DMRSK-W and DMRSR-Y, two DMR Mean . . . . . . . . . . . . . . . . . . . . . . 30 24,000 2,288 experimental varieties from CIMMYT (SW 8072 and 1.SD (5%,) . . . . . . . . . . . . . . . . . . 8 4,000 523 SW 8075), their respective populations (populations C.V., %,. . . . . . . . . . . . . . . . . . . . 27 16,000 23 2 and 5), and four maize varieties/populations recommended to and grown by many farmers in Note: The figures listed here are means of two locations. 'National Cereals Research Institute. Nigeria. Africa (TZB, TZPR, TZSR-Y-1 and Western Yellow). 'Instilute of Agricultural Kcsrarch and Training. Nigrria The experiment had a randomized complete block design with four replications, a plot size of four rows Table 23. Proportion of S1 families of DMRSR-W 6 rn long and spacing of 75 cm x 25 cm (net plot = two and DMRSR-Y segregating for streak center rows). Thr trial was planted a t two locations: resistance. IITA. 1982-83 i n a farmer's plot under natural downy mildew infection and a t an experiment s tat ion under Total No. and percentage Maize no. of segregating for artificial infection, both sites being in the Owo Local population Entries streak resistance Council Area of Ondo State, Nigeria. The percent incidence of downy mildew was recordedeight weeks UMRSR-W Early.. . . . . . . . . . . . . . . . . . 181 160 (88) after planting and the number of cobs and yield a t Idate. . . . . . . . . . . . . . . . . . . . 275 238 (.8 6,) harvest. DMRSR~Y At both locations the downy mildew resistant Early . . . . . . . . . . . . . . . . . . . 132 11 1 (84) varieties and populations were consistently superior Late. . . . . . . . . . . . . . . . . . . . 31 7 261 (82) From each population 250 ears were selected and Table 24. Pooulations contributin-e, t o the late. white. planted ear-to-row a t Owo in two sets; one set was streak resistant backup pool exposed to a mild level of artificially induced downy Krlat lve crrntrlbutlon mildew infection and the other to severe infection. to the first cycle Both populations had a high level of resistance even Parent population nf recombination. ?(, under severe downy mildew pressure (Figure 4). 22 Mezcla Tropical Blnnca. . . . . . . . . . . . . . . . . . . . . . 31 Resistant plants were selected for selling within 13LaPosta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1% entries that had a high downy mildew resistance TZR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 score and expressed good root and stalk quality. 34 Blanco Subtropical. . . . . . . . . . . . . . . . . . . . . . . . . . 11 Owing to the rather wide range of maturity within 29 Tuxpeno Caribe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 each population, the So ears were placed in early and 44 A.E.D. x 'ruxpeno . . . . . . . . . . . . . . . . . . . . . . . . . . 6 late groups. These subpopulations were planted 32 Eto Rlanco . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 28 Amarillo Dentado. . . . . . . . . . . . . . . . . . . . . . . . . . . 3 under streak pressure for half-sib recombination of Suwanl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . streak resistant plants during the 1982-83 irrig a tI' on 25 (Mix. 1 x Col. Gpo. 1) x Eto . . . . . . . . . . . . . . . . . season. As shown in Table 23, a high percentage of 26 Mczcla Amarilla . . . . . . . . . . . . . . . . . . . . . . . . . . . . the entries i n each subpopulation expressed streak 27 Amarillo Cristalino . . . . . . . . . . . . . . . . . . . . . . . . . resistance.-J.M. Fajemisin 33 Amarillo Subtropical. . . . . . . . . . . . . . . . . . . . . . . . 45 Amarillo dcl Bajio . . . . . . . . . . . . . . . . . . . . . . . . . . Late, whi te , s t r e a k res is tan t b a c k u p pool. The 36Cogollcro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . development and improvement of broad based gene 35 Antigua x Republica Dnminicana . . . . . . . . . . . pools is the best insurance against genetic erosion Earlv DMR cornnosite . . . . . . . . . . . . . . . . . . . . . . . and provides a source of superior germplasm for current and future breeding programs. A late, white, streak resistant backup pool is heing developed for C o n v e r s i o n of e x p e r i m e n t a l v a r i e t i e s t o TZSR-W-1 as a source of new and valuahle germplasm. s t r e a k resis tance. At IITA a conversion program is Several experimental varieties from different heing carried out to incorporate st,reak resistance populations in CIMMYT's international testing into experimental varieties from nine populations program and from IlTA and Southeast Asia were that have wide adaptation and perform well in crossed with streak resistant sources a t IITA, mainly Africa. These populations are part of the inter- TZSR-W and TZSR-W-1. Some of these crosses were national testing program organized by CIMMYT backcrossed to the nonresistant parent and then and have been described previously (IITA, Annual selfed once or twice for inbred line development. Report for 1981). Other crosses were selfed directly two or three times. Thr streak resistant sources available a t IITA The best late, white, streak resistant lines were were used as donors in a backcrossing program in recombined by bulk sibbing. The materials that which the best available experimental variety from contributed to this pool are listed in Table 24. each of the nine populations was used as a recurrent A total of 320 families with a high level of streak parent for each backcross generation. Two to three resistance are now in the third cycle of half-sib backcross generations have been developed already recombination and selection for agronomic charac- in each ofthese backgrounds. In addition t o selecting ters. New promising genetic material and intro- for streak resistance, CIMMYT maize breeders ductions will be fed into this pool. selected for plant and grain type and maturity group , -Frequency of lamlher ( % I o-n , -o f the recurrent parents in each generation. In six of these conversions, s t reak resistant families with good agronomic characters were Io~ nsn-r recombined in the BC2-F2 generation. The recom- bined ears were bulked, and the seed of these conversions was increased during the dry season. Five of these conversions are adapted to the lowland tropics and will enter streak resistant variety trials "I: to be tested in Africa during 1983. The sixth 40 conversion, of a n experimental variety from population 1 4 (American Early Dent x Tuxpeno), is adapted to midaltitude and subtropical areas and will be made available to national programs for testing. M. Rjarnason O H,.hl, Rerlr Mb- S".EOD~ rarirtom ton, rote,y ,,Ma Hybrid P r o j e c t .e*,s,on, Figure 4. Frequency distrihution of halfsih families of the A hyhrid maize research project was begun a t TITA in maize population DMRSK-W, DMRSR-Y and TZB (250 1979 t o develop inbred lines that are adapted to families each) under mild (Irft) and severe (right) downy tropical zones and have resistance, high combining mildew pressure, Owo, Nigeria, 15182. ahility and plant vigor. At the outset of the program, 24 Cereals Table 25. Number of S4 inhred lines developed in Table 26. Number of s t reak resistant S2m aize inbred IITA's hyhrid maize project by 1982 lines developed a t IITA, 1982 No. of I'ossihlc N....n. of Population S , lines adaptation Variety S2 lines Source CIMMYTa 7801, Katumani, e1.c. . . . . . . . . . $5 Kenya 21 Tuxpeno 1 . . . . . . . . . . . . . 10 1,owland tropics Tx 379 W . . . . . . . . . . . . . . . . . . . 28 Malawi 22 Mezcla Tropical Blanca . 164 Lowland tropics Ilonga, 7784, etc. . . . . . . . . . . . . 401 Tanzania 23 Blanco Cristnlina~l. . . 18 Lowland tropics ZCA, ZUCA. etc. . . . . . . . . . . . . 340 Zamhia 24 Antigua Veracruz 81 . . . . 22 Lowland tropics SK 52., R- 201. etc. . . . . . . . . . . . . 61 Zimbabwe 25 Blanco Cristalino~S. . . . . 17 Lowland tropics/ Ekona-W and Ekona-Y.. . . . . . 57 Cameroon subtropics Poza Kica 7722 . . . . . . . . . . . . . . 76 CIMMYT 26 Mezcla Amarilla. . . . . 39 Lowland tropics Across 7729. . . . . . . . . . . . . . . . . 52 27 Amarillo Cristalino-I.. . . 43 Lowland tropics Tocnmen (1) 7835. . . . . . . . . . . . 76 28Amarillo Dentado.. . . . . . 130 Lowland tropics TZSR-W-1 . . . . . . . . . . . . . . . . . . 117 lITA 29 Tuxpeno Caribc . . . . . . . . 69 Lowland tropics TZSR-Y-1. . . . . . . . . . . . . . . . . . . 50 32 Eto Blanco.. . . . . . . . . . . . 28 Lowland tropics/ TZMSR (midaltitude) streak resistant)". . . . . . . . . . 495 subtropics 3cj Amarillo Subtropical. . 54 Subtropics TZUT-Wb . . . . . . . . . . . . . . . . . . 212 T Z U T - ~ h . .. . . . . . . . . . . . . . . . 180 34 Blanco Subtropical . . . . . 110 Subtropics X 304C and X 304B. . . . . . . . . . . 274 Pioneer :35 Antigua Reuublica Dominicana.. . . . 8 8 Lowland tropics G 4747 and I2 4787 . . . . . . . . . . .A!! Funk (U.S.) TOTAI, . . . . . . . . . . . . . . . . . . . . 2.7110 36 Coeullero . . . . . . . . . . . . . . 38 Lowland t ro.~ i c,s l subtrr~pics "'I'ZMSK linrs were developed from IITA nridirltitudc. streak 38 PD(MS)6 H.E. oz... . . . . . 55 Lowland tvo.~ ic resistan1 populations (white dent and white flint).A ll lines ere , sl subtropics expectedt o be resistant to tbrcr major diseases highland blight 43 La Post.a. . . . . . . . . . . . . . . 281 1,owland tropics (H. turcicrm~)r.u st ( P .r orphi) and st.reak. 44 AED Tuxpeno . . . . . . . . . . 68 Midaltitude "TZIJT lines are segregating for rcslstance to m a i m strrak virus. 45 Amarillo Rajio . . . . . . . . . 12 Subtropics/tcmperatr Pool-16 (white dent). . . . . 172 Lowland tropics (Table 26). Attempts were also made t o extract eli te IITA inbred l ines directly from 12 CIMMYT populations, TLPB-EPS.. . . . . . . . . . . . . . . 21ab 1,owland trupics us ing correspondent experimental varieties wi thout TZB . . . . . . . . . . . . . . . . . . . . . 15 Lowland savanna crossing TTTA sources of s t reak resistance (TZSK-W ,l. L, SR (late). . . . . . . . . . . . . . . 5 1,owland tropics and TZSK-Y). TZSR (early). . . . . . . . . . . . . . 239 Lowland savanna In 1982 a special hybrid maize project was hegun TL (S5 lines). . . . . . . . . . . . . . 52 Lowland tropics wi th financial support from t h e government of TZDMRSll . . . . . . . . . . . . . . . 280 Lowland tropics Nigeria th rough t h e Grecn Revolution Technical (downy mildew) Subcommittee. The purpose of th is project i s to Asia" develop high yielding hybrid maize varieties t h a t a r e Suwan 1 + four UMK Lowland tropics adapted to t h e maize growing savanna a reas i n t h e populations. . . . . . . . . . . . . 82 (downy mildew) nor the rn par t of Nigeria. The main t r ia ls conducted Hawaii" under t h e hybrid project th i s year a re discussed i n Hi inhred l ines. . . . . . . . . . . . 229 Tropics/subtropics t h e following paragraphs. U.S. Corn Belt" Combining ability test for S3i nbred lines. Test R73, Mrrl7, etc . . . . . . . 329 Tropical savanna cross t r ia ls were conducted t o identify superior l ines ,I. O TAI, . . . . . . . . . . . . . . . . . 2,857 with h igh cornhining ability for subsequent de- velopment of single-cross hyhrids. One thousand and "S, hnrs wcrr derived from CIMMYl' and other populations/ sixty-seven S3streak res is tant l ines were tes t crossed lines that had been crossed with IITA streak resistant sources (TZSR~Wan with selected open pollinated varieties based on d TZSH-Y). "Susceptible to maize strcnk virus. All the other lines hare matur i ty a n d g ra in color. Six hundred a n d seven tes t itrcnk rrsistalice. crosses were made with l a te matur ing (110 t o 125 days) varieties; 417 of these were made wi th whi te t h e hest available high yielding maize populations and 190 wi th yellow varieties. F o u r hundred a n d a n d varieties from the CIMMYT a n d IITA maize sixty crosses were made with ear ly (90 t o 115 days) programs a s well a s materials from various Asian varieties, 269 of them wi th white a n d 191 with yellow countries, t h e University of Hawai i and ins t i tu t ions varieties. Fl int lines were crossed with den t varieties in t h e Corn Belt of t h e United Sta tes were used for a n d d e n t l ines wi th flint varieties since these crosses t h e extraction of desirahlc eli te inbred l ines adapted were expected t o have high combining ahility. t o the tropics. By 1982 a to ta l of 2,857 Sql ines, most of All t h e test cross progenies were planted dur ing them resistant t o maize s t reak virus, had been t h e 1982 growing season a t various locations in developed (Table 25). In addition, o the r promising Nigeria. Progenies for 644 crosses were planted a t varieties from some African nat ional programs and Ikenne (forest) from 11 t o 12 May, for 756 crosses a t from commercial seed companies had been added llorin (derived savanna) from 26 t o 28 May, for 1,056 26 Cereals Table 28. Number of inbred lines selected for single- made a t Samaru for the selection of lines adapted to cross hybrid production through diallel the savanna. crossing, IITA, 1982 Based on the combining ability test of the lines (in NO.o f Expected no. test cross trials) and their performance per se, 73 Maturity and lines of single- lines were finally selected for diallel cross hybrid grain color Adapt.ation selected" cross hybrids production during the dry season of 1982 under Late. white Savanna . . . . . . . . . . . 17 136 irriaation a t IITA (Table 28). Aouroximatelv 400 F I A. Latc, white l'orest . . . . . . . . . . . . . 10 45 s ini le crosses wili be produced for 1983.testini I,ate, yellow Savanna . . . . . . . . . . . 13 ~~ 78 throughout Nigeria. he diallel crosses a re be in i Late, yellow Forest . . . . . . . . . . . . . 10 45 produced according to maturity, grain color and Early, white Savanna/forest. . . . . . 10 45 adaptation to various regions. Early. yellow Savanna/forest. . . . . . . . . . . . . . . . . . -1"3 78 Various male sterile sources were introduced from 16 '"I the United States (Illinois Foundation Seed Co. I,td., "Selectton was hasrd on ylcld potential in test crosses alld inbred Pioneer International and University of Hawaii) and line performance per se. were tested a t IITA during the second season of 1982. that possess high combining abilit)~,t hc results of Selected, high combining seed parental lines will be those trials were taken into consideration in the converted for male sterility t o facilitate hybrid seed selection of inbred lines for. subsequent hybrid production in Africa. production. Combin ing abi l i ty t e s t f o r se lec ted o p e n Inb red l i nes p e r f o r m a n c e t r ia l . Successful pollinated varieties. The purpose of this trial was to production of commert:ial hybrid secd depends on find out which tropical maize varieties have the best high quality inbred lines. If used as male parents, the combining ability. Thc varieties are to be used by lines must have good vigor and agronomic traits to 1ITA's hybrid program in a reciprocal recurrent produce enough pollen. If used as female parents, selection scheme for inbred line development. Major they must produce good seed yields. The major p u r ~ emphasis has been placed on late maturing (120days) pose of this trial was t o evaluate t,he performance of white and yellow populations. A total of 15 selected the available lines and select only those that perform tropical maize varieties (9 white and 6 yellow), with well in addition to having high combining ability. their 51 diallel F1 crosses (36 white and 15 yellow), A total of 930 lines, mostly Sq,w ere planted a t four were planted a t four locations in Nigeria (Ikenne, different locations: Ikenne (7481, llorin (547) Samaru Ilorin, Samaru and Gusau). Each plot had four 5-m (878) and Gusau (418). The number of lines tested a t rows with three replicates. Only the two central rows each location was based on the maturity requirement were harvested for yield estimation. The yield of nine of the test location and availability of seed. The lines white varieties averaged 4.5 t/ha and ranged from 5.5 were evaluated for flowering date, plant vigor, (TZB) to 3.9 t /ha (TZPB). That of the 36 F1 crosses uniformity, reaction to prevailingdiseases, stalk and averaged 5.2 t /ha and ranged from 6.4 (TZB x Across root lodging, pollen production, ear aspects and secd 7721) to 4.5 t/ha, (Across 7823 x Poza Rica 7729), as yield potential. All the Sq lines tested were planted shown in Table 29. The array mean of all possible also a t Ibadan under artificial streak pressure, and nine crosses in each variety indicates that the white the selected lines were selfed. Pollination was also grain varieties with the best general combining Table 29. Average grain yields of nine tropical white maize varieties and their 36 F, crosses at four locations in Nigeria. 1982 TZSK- Across PR Across PR Across PK Array Parent TZR TZPB W - l 7721 7822 7823 7729 7832 7843 mean tjha T'B (flint) . . . . . . . . . . . . . . . . . . . . . , -5.5 5.5 5.4 6.4** 5.3 5.0 5.0 5.9** 1. Z PB (dent).. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7* 5.1** 5.0 4.7** 4.9** 5.6** TZSR-W-1 (flint) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 .4 5.0** 4.8 4.9** 5.5** 4.7 Across 7721 (dent). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 5.7** 5.1t* 5.1** 5.6** Plt 7822 (dcnt) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 4.7 5.8** 5.2 Across 7823 (flint).. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9. 4.5 5.9** PR 7729 (flint.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-4.. 4 4.7 Across 7832 (flint).. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-4. . 5 PR 7843 (dent) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Parent variety mean. . . . . . . . . . . 4.5 F mean . . . . . . . . . . . . . . . . . . . . . . 5.2 cb..'/, . . . . . . . . . . . . . . . . . . . . . . . . 23.7 S.E . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.103 *Significant.lyd~f~ereantt t h p j'x, level from the. ~ieldof thr high yielding parant,, **Significantly dill'erent at tlir I,%, lrvel. Cereals 27 Table 30. Average yields of six tropical yellow maize varieties and their 15 F, hybrids a t four locations in Nigeria, 1982 TZSR- Across LM Western Array Parent Y-l MMB 7728 7827 Suwan 1 yellow mean tlha TZSR-Y-l(flint). . . . . . . . . . . . . . . . . -4.6 5.2** 4.5 4.6 5.2** 4.6 4.8 MMB(dent) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 .4 4.7 4.4** 4.2** 51** 4.7 Across 7728 (dent). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 .8 4.6 5.4** 4.6 4.8 LM 7827 (flint). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 .8 5.4** 4.6** 4.7 Suwanl(flint). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 5.2** 5.1 Western Yellow (dent). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -4.8 Parent variety mean.. . . . . . . . . . . . 4.2 F I mean . . . . . . . . . . . . . . . . . . . . . . . 4.8 C.V.,% . . . . . . . . . . . . . . . . . . . . . . . . 25.4 S.E. . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.111 'Significantly different at the 5"/, level from the yield of the high yielding parent **Significantly different at the 1% level. ability were TZB (5.5 t/ha) and Across 7721 (5.5 t/ha), Based on their streak anddowny mildew resistance followed by Poza Rica 7843 (La Posta) and Across and general and specific combining ability, TZSR-Y-1 7832 (Eto). (which is resistant to streak) and Suwan 1 (which is The heterotic eflects of FI crosses from the mid- resistant to downy mildew) may be selected as hase parental value were quite variable, depending on the populations for yellow line development. combination. The average heterotic effect ofthe 31 F1 The general heterotic patterns of dent x dent, dent crosses in late white varieties was 16.4%, (Table 29). x flint and flint x flint crosses with both the white Among the white varieties, five crosses showed over and yellow varieties used in this test are summarized 30%, heterotic effect: Across 7823 x Across 7832 in Table 31. The nine dent x dent crosses showed the (35.60/,),T ZSR-W-1 x Poza Rica 7843 (34.1%,), Across highest heterotic effect (19.9%), followed by dent x 7832 x TZPB (33.3%), Poza Rica 7729 x Poza Kica flint (16.7%) and flint x flint (13.8%,). Although 7843 (31.8%) and TZB x Across 7721 (30.6%). various crosses were made between different grain On the basis of their disease resistance, general types, the average heterotic effects of dent x dent and specific combining ability, and heterotic effect, and dent x flint crosses were higher than those of the TZSR-W-1 (which is resistant to streak) and Poza flint x flint crosses. These results agree with the Rica 7843 may be selected as hase populations for general heterotic pattern in maize.-S.K. Kim, Y. reciprocal current selection in the white line Efron, F.H. Khadr and J.M. Fajemisin development program. As shown in Table 30, the yield of six yellow National and International Yield Trials varieties averaged 4.2 t/ha and ranged from 4.8 for In cooperation with other research institutions, IITA Across 7728 to 3.4 t/ha for Milo Maya Brazil (MMB). conducted the following trials of promising ex- Yield of the 15 FI crosses averaged 4.8 t/ha and perimental maize varieties a t Samaru and Gusau in ranged from 5.4 (Across 7728 x Suwan 1, La Maquina northern Nigeria during 1982: Nigerian national 7827 x Suwan 1) to 4.2 t /ha (MMB x Suwan 1). zonal trial (early and late maturing varieties) Suwan 1, a downy mildew resistant variety from CIMMYT international trials (EVT 14A and 14B) Thailand, showed the highest array mean (5.1 t/ha) and SAFGRAD regional trials (RUVT-1 and -2). estimated from all possible five crosses. The average The results of these trials are discussed in the heterotic effect ofthe 15 F1 crosses in yellow varieties following ~ a r a g r a p h sa nd summarized in the was 16.2%,, about the same as that of the white accompanying tables. It should be noted that a severe varieties. Among the yellow varieties, three crosses storm immediately after flowering caused a high showed over 30% heterotic effect: MMB x Western degree of lodging in many of the trials a t Samaru, Yellow (37.8'j6), La Maquina 7827 x Suwan l(31.7) making it extremely difficult to record plant counts and Suwan 1 x La Maquina 7827 (31.7%). and yield data a t harvest. The high C.V.s were due mainly to the Striga infestation in some parts of the Table 31. Average heterotic effects in crosses among experimental plots, notably in Gusau. trooical late maize varieties. IITA. 1982 National zonal maize variety trials. Pirsabak Number of Heterotic (1) 7930 a t Samaru and Pool-16 a t Gusau were the Combination crosses effect, % highest yielding varieties in the early maturing Dent x dent.. . . . . . . . . . . . . . . . . . . . 9 19.1 maize trials tested a t these two locations (Table 32). Dent x flint . . . . . . . . . . . . . . . . . . . . . 29 16.7 Differences in yield among the entries tested, Flintx flint . . . . . . . . . . . . . . . . . . . . . 13 13.8 Avrraee . . . . . . . . . . . . . . . . . . . . . . . . however, were not statistically significant a t the 5% 51 16.4 level in the Samaru trial. Nor were there significant 28 Cereals differences a t the 5% level among varieties entered in information about the highest yielders i n comparison the long duration trials at Samaru and Gusau. with the local check. TZSR-Y-1 yielded significantly CIMMYT in terna t ional trials. more than the check a t the 5% level of probability. Table 33 contains the results of trials of early maturing yellow maize But in view of the much lower number of plants (EVT 14A), in which there were 17 entries, including harvested and the shorter stature of the local check, three local checks, and trials of early, white maize the yield of the local check could have been (EVT 14B), which had 17 entries. These trials were underestimated.-H.N. Pham conducted a t Gusau. In EVT 14A varieties extracted from population 31 (Amarillo Cristalino-2) and Entomolorv population 35 (Antiqua x Republica Dominicana) were the top yielders. Data from EVT 14B show that Maize breeding for resistance to stemborers has been the experimental varieties from population 32 (ETO carried out a t IITA for the last several years. In Blanco) ranked a t t he top. It should be noted, screening under severe natural infestation by the however, that there were no significant differences at pink stalk borer (Sesamia calamistis) a t Umudike, the 5% level between these top yielding varieties and Nigeria, the response of more than 2,000 different the best local checks (Pool-16 Gusnu in EVT 14A and maize genotypes, including IITA developed lines, ............. ...... Pirsabak (1) 7930 SK B C (~F, ) in EVT 14B). was compared. S- r..r e- e- -n--i-n ~ np o- -f field r.r.n. r. ns .fo.r. .re.s istance nnrler SAFGRAD regional t r ials . RUVT-1 compared natural growing conditions and optimal natural t he performance of promising. early maturing- insect uressure is the cheawest method of ulant varieties from various hreediug programs. selection. It has one drawback, however, tha t may Temperate x Tropical No. 42 and Temperate x hinder progress in breeding resistant maize culti- Tropical No. 3 were the highest yielding maize vars. Since some plants may escape natural infesta- varieties tested a t Samaru and Gusau, respectively, tion, lines may be wrongly classified as resistant but there was no significant difference between the when in fact they were never infested. yield of these varieties and that of the local check This problem can he eliminated through homo- (Table 34). Grain moisture a t harvest, in contrast, genous artificial infestation. Intensive work on varied widely among the test entries. rearing of stem borers on artificial diets has been RUVT-2 was designed to test late maturing maize carried out a t llTA this year, including the rearing of varieties. Table 35 presents yields and other large populations of the pink stalk borer (Sesamia Table 32. Results of Nigerian zonal trials, Samaru and Gusau, Nigeria, 1982 Yield in t/ha and rank Percentage of graln moisture No of plants Samaru Gusau Mean Samaru Gusau Mean harvested Early varieties" Pirsabak(1) 7930. . . . . . . . . . . . . . . 4.54 (1) 5 . 1 2 4.83 (1) 30.9 20.1 25.5 39.8 Pool-16.. . . . . . . . . . . . . . . . . . . . . . 3.82 (6) 5.58 (1) 4.70 (2) 28.3 18.8 23.5 42.3 Kewesoke-W . . . . . . . . . . . . . . . . . . 4.23 (3) 4.67 (3) 4.45 (3) 30.9 18.5 24.7 39.7 Kewesoke-Y . . . . . . . . . . . . . . . . . . 4.09 (4) 4.67 (3) 4.38 (4) 30.1 20.5 25.3 34.0 TZESR-W.. . . . . . . . . . . . . . . . . . . . 4.33 (2) 4.24 (6) 4.28 (5) 37.8 19.5 28.6 34.8 TZESR-Y . . . . . . . . . . . . . . . . . . . . . 3.97 (5) 4.52 (5) 4.24 (6) 30.8 19.5 25.1 34.3 NE-Y . . . . . . . . . . . . . . . . . . . . . . . . 3.10 (7) 2.95 (7) 3.02 (7) 39.9 23.0 31.4 36.7 Mean . . . . . . . . . . . . . . . . . . . . . . . . 4.01 4.45 LSD(5X) . . . . . . . . . . . . . . . . . . . . . 1.29 1.10 CV, %. . . . . . . . . . . . . . . . . . . . . .2 1.6 20.5 Long duration varieties NSI-Y-1 . . . . . . . . . . . . . . . . . . . . . . 3.83 ( 3 ) 5.39 (3) 4.61 (1) 29.9 23.1 26.5 37.5 Ife Yellow Comp.. . . . . . . . . . . . . . 3.58 ( 5 ) 5.51 (1) 4.54 (2) 28.3 22.9 25.6 32.6 TZB (check). . . . . . . . . . . . . . . . . . . 3.89 (2) 4.84 (6) 4.36 (3) 31.9 28.2 30.0 36.1 La Maquina 7928 . . . . . . . . . . . . . . 3.80 (4) 4.88 (4) 4.34 (4) 31.7 25.6 28.6 361 WesternYellow (check) . . . . . . . . 3.90 (1) 4.77 (8) 4.33 (5) 31.7 27.6 29.6 35.6 TZSR-W-1... . . . . . . . . . . . . . . . . . . 2.94 (10) 5.49 (2) 4.21 (6) 30.1 23.5 26.8 35.1 Los Diamantes 7823. . . . . . . . . . . . 3.09 (8) 4.83 (7) 3.96 (7) 27.6 21.1 24.4 33.3 PozaRica7843 . . . . . . . . . . . . . . . . 3.04 (9) 4.87 (5) 3.95 (8) 27.6 24.0 25.8 34.7 KSPH~W-1. . . . . . . . . . . . . . . . . . . . 3.16 (7) 4.65 (9) 3.90 (9) 23.7 25.0 24.3 31.8 TZSR-Y-1. . . . . . . . . . . . . . . . . . . . . 3.17 (6) 3.94 (10) 3.55 (10) 24.6 29.8 27.2 37.0 Mean . . . . . . . . . . . . . . . . . . . . . . . . 3.44 4.92 LSD (5%). . . . . . . . . . . . . . . . . . . . . 1.61 1.16 CV,%. . . . . . . . . . . . . . . . . . . . . . . .3 2.3 20.3 "Variety IIMR-YE was rxcluded from thc analysis hecausr of its poor germinnt.iun. calamistis). t h e s u g a r c a n e s t a l k bore r ( E l d a n a but t h e occurrence of d iapause significantly reduced saccharina) a n d t h e spotted borer (Chilo partellus). t h e p roduc t iv i ty of t h e co lony . T h e effect of Initial experiments on laboratory rear ing of maize temperature . humidi ty a n d die t composition on borer (Busseola fusca) showed t h a t t h e larvae easily incidence of l a rva l d iapausc is presently being accepted the diets used for o the r s tem borer species. investigated . Table 33 . Results of CIMMYT regional trials. Gusau. Nigeria. 1982 Yield. Percentage of best Plant Ear Variety t/ha check's yield Mo~stur.e 'y o height . cm height. cm EVT 14A Pichilingue 7931 . . . . . . . . . . . . . . . . . . . . . . . . 5.02 Islamabad 8035. . . . . . . . . . . . . . . . . . . . . . . . . . 4.80 Sete Lagoas 7931 . . . . . . . . . . . . . . . . . . . . . . . . 4.75 Across 7726 RE . . . . . . . . . . . . . . . . . . . . . . . . . . 4.65 Suwan8035 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.45 Pool-16 Gusau (best check) . . . . . . . . . . . . . . . 3.82 LSD (5%) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.31 C.V .. % . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 3.3 EVT 14B Alaiuela 8032 Poza Rica 8032 . . . . . . . . . . . . . . . . . . . . . . . . . . 5.22 Cotaxtla 8032 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 .66 Ilonga (1) 7930 . . . . . . . . . . . . . . . . . . . . . . . . . . 4 .64 Kisanga7930 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.45 Pirsabak (1) 7930 SR (best check) . . . . . . . . . . 4.62 LSD (5%) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.17 C.V..%, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.0 Table 34 . Results of SAFGRAD regional t r i a l RUVT.1. Gusau a n d Samaru. Nigeria. 1982 . Yield in t/ha and rank Percentage of grain moisture Variety Samaru Gusau Mean Samaru Gusau Mean Temp . x Trop. No . 3 . . . . . . . . . . . . . . . . . . . 4.23 (3) 6.00 (1) 5.11 (1) 29.4 23.1 26.2 Temp . x Trop . No . 42 . . . . . . . . . . . . . . . . . . 4.55 (1) 5.26 (5) 4.90 (2) 28.8 19.6 24.2 718 CDN-I 18 Comp . D . . . . . . . . . . . . . . . . . . . 4.33 (2) 5.28 (4) 4.80 (3) 29.0 20.8 24.9 TZESR-W . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.48 (6) 5.90 (2) 4.69 (4) 30.6 18.6 24.6 Pirsabak (I) 7930 . . . . . . . . . . . . . . . . . . . . . . 26.5 17.6 22.0 Local check . . . . . . . . . . . . . . . . . . . . . . . . . . 36.5 18.5 27.5 MTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.5 18.2 21.8 EV 7982 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.0 22.4 25.7 SAFITA-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.1 19.3 25.2 ~001.27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.07 (9) 4.30 i lo j 3.68 (ioj 22.7 18.8 20.7 SAFITA-104 . . . . . . . . . . . . . . . . . . . . . . . . . . 2.18 (12) 4.60 (8) 3.39 (11) 25.5 17.7 21.6 Comp . 77 BD . . . . . . . . . . . . . . . . . . . . . . . . . . 2.35 (11) 3.57 (12) 2.96 (12) 37.3 28.0 32.6 Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.41 4.89 L D ~. . .. . . . . . . . . . . . . . . . . . . . . . . .1 .32 1.47 Table 35 . Results of SAFGRAD regional t r i a l RUVT.2. Gusau. Nigeria. 1982 Grain Percentage of Plant Ear No . of plants Variety yield. t/ha check's yield Moisture. % height. cm height. cm Lodging. "/, harvested TZSR-Y-1 . . . . . . . . . . . 5.46 138 27.3 202 116 15.1 36.5 Temp . x Trop . No . 27 . 5.31 134 20.8 191 90 8.5 35.7 Golden Crystal . . . . . . 5.20 132 24.8 202 97 19.2 35.5 TZPB . . . . . . . . . . . . . . . 4.56 115 22.6 202 107 31.0 37.7 Comp . 4 . . . . . . . . . . . . . 4.50 114 20.7 237 132 11.7 41.2 Local check . . . . . . . . . 3.95 100 19.9 180 81 T2.3 26.0 LSD (5%) . . . . . . . . . . . 1.48 C.V .. %. . . . . . . . . . . . . . 22.6 Stalk R o t s Frequency of susceptible plants ( % I An experiment was carried out to determine the best age at which to inoculate maize with stalk rot patho- gens. Two maize varieties were used: TZESIZ-W, an early maturing (90 days) variety, and TZSR-W-1, a 25 late maturing (120 days) variety. The plants were inoculated 4, 6, 8 and 10 weeks after planting. The pathogen treatments were Macrophomina phaseoli (agent for charcoal rot), Diplodia maydis, I?usarium moniliforme (seed isolate), F. moniliforme (stalk isolate), a maize soil suspension and a check. Each of the pathogens was raised on sterilized toothpicks. Uninfested, sterilized toothpicks were used as the check. A factorial combination of the treatments was tested in a randomized complete block design with four replications, a plot size of four rows 3 m long and spacing of 75 cm x 25 cm. For each of the treatments, the first fully elongated internode of eachplant in the two center rows was inoculated. At maturity the stalks were split longitudinally for rot evaluation, using a scale of 0 to 4, where 0 = no rot and 4 = 100'%, rot of the inoculated internode. As observed in a similar experiment last year, inoculation four weeks after planting was not effective (Table 38). Inoculation eight weeks after planting gave the highest average rot scores, but these were not significantly different from ratings for inoculation six weeks after planting From the 1981 and 1982 data, i t was concluded that at four weeks after planting, maize cannot be reliably evaluated for stalk rot infection using the toothpick method. Inoculation a t eight weeks has given the most consistent results, and inoculation a t six weeks is also reliable, particularly for early maturing varieties (Figure 7). The time for reliable stalk rot, inoculation corresponds approximately to the Weeks after planting midtasseling stage for both late maturing (eight Figure 7. Effect of age at inoculation on the susceptibility weeks after planting) and early maturing (six weeks) of two maize varieties to Fusarium stalk rot, TITA, 1982. varieties. F. moniliforme induced the greatest degree of rot, TZESR-W, an early maturing (90 days) variety, and although there were no significant differences TZSR-W-I, a late maturing (120 days) variety. Four between the seed and stalk isolates. Diplodia was methods of inoculation were tested: a pathogen more important than Macrophomina under the infested toothpick was inserted through the shank, conditions of the experiment. The soil suspension middle of the ear and tip of the ear, and fungal was not appreciably better than the check treatment suspension was injected through the tip of the ear. in inducing rot. The data indicate that the technique The pathogens used were Macrophomina phaseoli, cguld he used to evaluate plants for Fusarium sp., Diplodia maydis, Fusarium moniliforme (seed which is the most prevalent organism causing stalk isolate), F. moniliforme (stalk isolate), a mixture of rot in the various ecological zones of the tropics. these pathogens and a check (uninfested toothpick or Figure 8 shows the wide variation among plants in sterile distilled water with the suspension method). reaction to Fusarium stalk rot. Using this t,echnique Inoculation was carried out 7 to 10 days after midsilk. and the appropriate breeding method, the sensitive At maturity the ears were harvested and evaluated plants can be progressively eliminated in the on a scale of 1 to 4, where 1 = no rot and 4 = severe population/variety. rot. Ear R o t s As in the 1981 experiment, inoculation with an infested toothpick through the middle of the ear gave An experiment to evaluate different methods of ear the highest rot score for every pathogen treatment in rot inoculation was repeated this year using three all three varieties (Table 39). F. moniliforme was the maize varieties: one opaque-2 high-lysine variety most effective in causing rot under the conditions (NCBRbo2) and two normal-grained varieties, of the experiment, and there was no significant 34 Cereals difference between the seed and stalk isolates. The spore suspension through the ea r tip was not mixed inoculum treatment induced mostly Fusarium effective for Macrophomina and Diplodia, i t was symptoms. There was a significant interaction reliable for Fusarium. There were no significant between the method and pathogen. This was evident differences among varieties. from the fact that, although inoculation with the Rhizoctonia solani is a common pathogen of maize in the humid rain forest region of Africa. The entire Frequency of plants (%) shoot is susceptible to this pathogen, which is known for its wide host range (including cereals, legumes and root crops). Owing to the high incidence of this '0pathogen in 1982 on maize a t Suakoko (Liberia), N'tonm (Gabon) and Ikenne (Nigeria), an experiment was set up t o determine a reliable inoculation technique to be used in a study of this pathogen. Four inoculation methods were used: the sclerotia of th e fungus (raised on potato dextrose agar medium) were deposited through the shank, the middle of the ear and ear tip with a galvanized nail dipped in 90% ethanol and placed between the ear and the stalk. Two maize varieties (TZPB and TZSR-W-1) were used hut in two separate experiments. Ten replicat,es (five ears per replicate) were arranged in a completely randomized design. Inoculations were carried out 7 t o 10 days after midsilk. At harvest rot damage was rated on a scale of 1 to 4. Inoculating the middle of the ear gave the highest rot score for both varieties, followed by placing the sclerotia between the ear and stalk (Table 40). Results for shank and ear tip inoculations were not consistent for both v a r i e t i e s . J.M. Fajemisin Table 40. Ear rot scores on maize inoculated with Rhizoctonia solani, IITA, 1982. M- - a ize~ varieties Inoculation method TZPB TZSR-W-1 Shank . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7 1.1 Midear . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 2.8 Ear tip . . . . . . . . . . . . . . . . . . . . . . . 1.0 1.3 Between ear and stalk. . . . . . . . . . . . . . 1.8 1.5 LSD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 0.4 C.V.,% . . . . . . . . . . . . . . . . . . . . . . . . . . 27.5 27.8 Figure 8. Distribution of maize plants (combined data for Note: Ear rot was rated on a scalo of 1 t o 4, where 1 = 0 , %= 1 to TZESR-W and TZSR-W-1) according to their reaction to 10,3 = 11 to 100 and 4 = ovw 1W rotten kernels per ear. Fusarium stalk rot, IITA, 1982. Table 39. Effect of inoculation method and pathogen on the severity of maize ear rot, IITA, 1982 Pathogen Macro- Diplo- Fusariun Fusarium Mixture of Method phomina dia (seed isolate) (stalk isolate) all pathogens Check mean Toothpick, ear tip. . . . . . . . . . . . . . 1.0 1.0 1.4 1.5 1.4 1.3 1.27 Toothpick, midear . . . . . . . . . . . . . 1.0 1.4 2.1 2.1 2.4 1.7 1.78 Toothpirk, shank.. . . . . . . . . . . . . 1.0 1.0 1.3 1.4 1.4 1.2 1.22 Spray. silk.. . . . . . . . . . . . . . . . . . . 1.0 1.0 1.6 1.6 1.4 1.3 1.32 Pathogen mean. . . . . . . . . . . . . . . . 1.00 1.10 1.60 1.65 1.65 1.38 LSD (5%,). . . . . . . . . . . . . . . . . . . . . 0.06 0.06 C.V.,'Yo.. . . . . . . . . . . . . . . . . . . . . . 11.2 13.3 Note: Ear rot was rated an a scale of 1 t o 4, where 1 = 0 , 2 = 1t o 10.3 = 11 to 100 and 4 = over 100 rotten kernels per ear. Each figure is amean of three maize varieties, with each variety replicated three times and 25 plants per replicate. 36 Cereals After low speed centrifugation, the virus in the antiserum obtained from Wooster against the maize supernatant was precipitated by adding 0.2 M NaC1 stripe virus (Gingery et al, 1981) as well as an and 10% polyethylene glycol. The virus was further antiserum against noncapsid protein. which is purified by two cycles of differential centrifugation. associated with this disease (Balk and Tsai, 1982), The partially purified preparation was layered on top reacted with sap from maize stripe infectcd plants of a sucrose density gradient. A single peak was fromNigeria. There was also a positive reaction with observed, which was collected and concentrated. Rottboellia exaltata plants that showed maize stripe This virus preparation was layered on a second symptoms. sucrose density gradient, and the virus was Based on the persistent transmission of the recovered as before. Nigerian isolate of maize stripe by Peregrinus Numerous virus particles could be associated with maidis, t he symptoms it causes in maize and the band in the gradient. The particles were spherical especially its serological relationship with maize and about 40 nm in diameter. The virus fraction was stripe virus from the United States, it appears likely assayed for infectivity by a membrane feeding that the two isolates are related or identical.-G. method, using virus free leafhoppers. The leafhop- Thottappilly and H. W. Rossel pers transmitted the virus, and the maize seedlings showed typical symptoms both of mottle and chlorotic stunt. SAFGRAD Project in Upper Volta Rabbits were immunized by six weekly in- Genetic Improvement tramuscular injections with 1 ml of a purified preparation emulsified with 1 ml of Freund's The maize breeding program of the Semi-Arid Food Grains Research and Development (SAFGRAD) incomplete adjuvant, followed by two intravenous injections. Rabbits were bled 10 days after the last Project was initiated in 1978. Most of the work so far injection and weekly thereafter. The antiserum has been concentrated in the 700- to 900-mm rainfall reacted with purified virus preparations in an agar zone. The major objectives of this work are todevelop gel diffusion test. However, no positive reaction and identify early maturing varieties (85 to 90 days) could be obtained using crude juice. with reasonably good yields (4 t/ha) and to distribute Maize mottle virus can be differentiated from many the promising materials through various national other viruses from graminaceous hosts by its programs, 27 of which are participating in the symptomatology, by its not heing gap tr;msmissible SAFGRAD Project. In all maize breeding trials and and by its transmission by the leafhopper, Ciuadulina breeding nurseries during 1982, NPK was applied a t triangula. Further, in an agar diffusion test, purified 74:46:30 kg/ha, and plant populations were 53,000 maize mottle virus preparations did not react with per hectare. the antisera against several graminaceous viruses Earliness and yield. Three approaches are being with spherical particles, such as cocksfoot mild followed in breeding for earliness and good yield: (1) mottle, phleum mottle, panicum mosaic, cocksfoot selection for yield in early maturing populations, (2) mottle, molinia streak, cynosurus mottle and rice selection for yield and earliness in temperate x yellow mottle viruses. Also, an antiserum produced tropical germplasm, and (3) crossing early with against a spherical virus in Rottboellia exaltata medium maturing populations and selecting for both (IITA, Annual Report for 1981) did not react with yield and earliness in segregating generations. maize mottle/chlorotic stunt virus. Full-sib recurrent selection in eight early ma- turing populations was begun in 1980. Based on 1981 Maize Stripe Disease trials, a total of 24 experimental varieties were developed by combining 8 to 10 selected families of Maize stripe is a disease of maize in many African the various populations involved. These experimen- countries and a major problem with maize pro- tal varieties were tested in a trial with a randomized duction in S i o Tom6 (Rossel, unpublished data). block design a t Kamboinsii and Loumhila during Maize stripe disease has also been reported from the 1982. Table 41 gives the performance of sclected United States, Venezuela and Peru. Although some varieties compared to the check variety. There was workers have reported that an isometric particle is no significant difference in yield among the varieties associated with maize stripe disease, this has not at Loumbila. However, a t Kamboinsk, E.V. Across been confirmed by studies done in the United States TZE 12 Y and E.V. Kamboinsk TZE 12 Y yielded and IITA. Work done a t the College of Wooster, significantly higher than the check variety. E.V. United States, indicates that the disease is caused Across TZE 12 Y performed well a t Loumhila also. hy an unusual filamentous nucleoprotein approxi- This variety will be further tested in large plots at mately 3 nm in diameter that is considered to be a various locations in 1983. member of a new virus group. To identify early maturing, high yielding varieties, In order to see whether maize stripe in Nigeria is several promising varieties developed by various related to the disease reported from the United international and national institutes were tested in States, infected samples were tested using antisera regional uniform variety trial 1 (RUVT-1) with a ran- against this virus. In an agar gel diffusion test, the domized block design a t Kamboinsk and Loumbila. Cereals 37 Table 41. Performance of selected experimental varieties and results of regional uniform variety trial 1, Upper Volta, 1982 Yield at Yield at Average Loumbila, Kamboinse, Yield, Days to Plant Ear Variety kgjha kglha kglha flower height, cm height, cm Test of experimental varieties E.V. Across TZE 15 Y . . . . . . . . . . . . . . . . . . . E.V. Across TZE 12 Y . . . . . . . . . . . . . . . . . . . E.V. Kamboinse TZE 8 Y . . . . . . . . . . . . . . . . E.V. Across TZE 16 Y . . . . . . . . . . . . . . . . . . . E.V. Kamboinsk TZE 12 Y . . . . . . . . . . . . . . . E.V. Saria TZE 16 Y. . . . . . . . . . . . . . . . . . . . . Pool-27 (check) LSD (5'jb). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ns C.V .,%. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35.6 Regional uniform variety trial 1 Temperate x Tropical Filler No. 3 . . . . . . . . 6,080 TZESR-Y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,547 E.V.7982 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,853 E.V.Pool.16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,013 Pool-27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,960 Temperate x Tropical Filler No. 42. . . . . . . 5,173 MTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,960 Comp. 77 BD . . . . . . . . . . . . . . . . . . . . . . . . . . 4,533 TZESR-W. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6,187 Pirsaback (1) 7930 . . . . . . . . . . . . . . . . . . . . . . 5,173 DMR-Ye . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,427 E.V. Across Pool-16.. . . . . . . . . . . . . . . . . . . . - Poo1.18 - Early Yellow. . . . . . . . . . . . . . . . . . . . . . . . . . . - Jaune Flint de Saria (local check). . . . . . . . . 4,533 Average . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,120 LSD(50/,). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ns C.V .,y.u. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.6 This trial, coordinated by the IITAISAFGRAD pro- Table 42. Performance of selected full-sib families of gram, was sent to 20 countries in 1982. The results Pool-16 and TZESR-Y. Kamboinse., U.o.o er obtained in Upper Volta are presented in Table 41. Volta, 1982 Twelve varieties were tested in this trial. Although Days Plant Ear the differences in yield among the varieties were not Yield, to height, height, statistically significant a t KamboinsB, TZESR-W, kg/ha flower cm cm Temperate x Tropical No. 3 and TZESR-Y yielded 22 Mean of selected to 36% more than the local variety. At Loumbila Pool-16 families. . . . . . none of the varieties tested performed significantly Mean of all Pool-16 better than the check. families tested . . . . . . . In a n effort to increase the yield of early maturing Checks: composites, population improvement was carried out Pool-16 . . . . . . . . . . . . . following the full-sib method in one yellow grained Jaune Flint de Saria. . composite, TZESR-Y, and one white grained Mean of selected TZESR-Y families. composite, Pool-16. The full-sibs in Pool-16 were Mean of all TZESR-Y developed during the dry season of 198182 a t families tested . . . . . . . Kamboinsb and in TZESR-Y a t IITA. Two hundred Checks: and fifty full-sibs of Pool-16, along with six checks, TZESR-Y. . . . . . . . . . . . were tested a t Kamboinsb in regional full-sib testine Jaune Flint de Saria. . trial 1. One hundred and sixty-fiie full-sibs of^^^^^ Y, along with four checks, were tested in another Over the last three years, several populations trial a t KamboinsB. Based upon the yield, days to representing temperate x tropical germplasm have flower and other agronomic characters, 12 full-sibs of been recombined and mildly selected through selec- Pool-16 and 13 of TZESR-Y were selected. The tive bulk sihbing a t KamboinsA. In 1982,Zl promising performance of selected full-sib progenies of Pool-16 populations, along with four checks, were tested in a and TZESR-Y is given in Table 42. Experimental trial with a randomized block design a t Kamboinse varieties are being developed, utilizing the remnant and Loumbila. Table 43 records the performance of seed of selected families of both populations. These selected populations, compared to check varieties. varieties will be tested in regional trials during 1983. There were significant differences in yield among 38 Cereals Table 43. Performance of selected temoerate x troaical aooulations. Uooer Volta. 1982 Yield at Yield at Average Loumbila, KamhoinsB, Yield, Days to Plant Ear Population kg/ha kg/ha kg/ha flower height, cm height, cm Temperate x Trtrpical: No.66 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,360 5,120 6,240 43 197 93 No.18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8,000 4,053 6,027 46 172 92 No .6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,894 3,734 5,814 43 169 83 No.73 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,040 4,214 5,627 44 189 87 No.42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,680 2,934 5,307 45 187 93 No.14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,254 3,334 5,294 47 193 90 No.27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,574 2,987 5,281 50 179 88 No.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,680 2,560 5,120 46 187 96 Check: Pool-27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,440 3,013 4,227 41 167 92 SAVITA-104 . . . . . . . . . . . . . . . . . . . . . . . . . 5,654 3,334 4,494 39 177 73 E.V. Kamhoinse Pool-16 . . . . . . . . . . . . . . . 6,400 3,587 4,994 41 185 92 SAVITA~lOZ. . . . . . . . . . . . . . . . . . . . . . . . . 8,854 4,480 6,667 51 190 97 LSD (5%). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,408 1,546 C.V., y,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.9 22.0 the varieties a t both locations. Among the early agronomic characters, 13 have been selected (Table maturing check varieties, E.V. Kamboinsi: Pool-16 44). These populations will he tested again in 1983, was the highest yielding entry at both locations. and the most promising ones will he utilized in (SAFITA-102y ielded more, hut it is a later maturing developing one or two composites. variety). A few populations, including Temperate x Tropical No. 66, No. 18 and No. 6, yielded 16 to 25% Medium matur ing populations. In addition to higher than E.V. Kamboins6 Pool-16. breeding for early maturing varieties, the IITA/ The remaining temperate x tropical materials, SAFGRAD project is also developing and identifying along with the promising populations indicated medium maturity varieties, particularly for the zone above, were tested in another trial a t Kamboinsb. A of the semiarid tropics that receives 900 to 1,100 mm total of 81 materials, along with check varieties, were of rainfall annually. RUVT-2, a regional uniform included in this trial. Based on the yield and other variety trial consisting of 12 medium maturity varieties was organized in 1982 and sent to 18 Table 44. Performance of selected temperate x countries participating in the SAFGRAD project. tropical populations, Kamboinse, Upper This trial was conducted a t Kamboinsi., Loumhila Volta. 1983 and Farako-Bi in Upper Volta (Table 45). There were Average significant differences in yield among the varieties a t Days Plant Ear Kamboinsi! and Farako-Bi. IRAT-178 produced the Yield, to height, height, highest yields a t all locations. Elite x EM Comp., Population kg/ha flower cm cm Fereke 7622 and Comp. 4 also showed promise a t Temperate x tropical: Kamboinsb, Farako-Bi and Loumbila, respectively. Nu. 2 . . . . . . . . . . . . . . . 4.069 49 179 89 Two trials, early variety trial (EVT) 1GA and EVT No. 38 . . . . . . . . . . . . . . 3,669 50 178 81 16B, were conducted a t Kamboinse to test medium No. 66 . . . . . . . . . . . . . . 3,589 48 160 67 maturing varieties developed by CIMMYT. Twenty- K. 81 No. 58 . . . . . . . . . 3,546 48 164 80 four varieties were tested in EVT 16A and 16 in EVT No. 33 . . . . . . . . . . . . . . 3,536 48 154 73 1613. Differences in yield among the varieties tested N o 2 5 . . . . . . . . . . . . . . 3,493 52 181 94 in both the trials were statistically nonsignificant. No. 9 . . . . . . . . . . . . . . . 3,402 51 168 81 Moreover, none of the varieties gave a higher yield K.81No.46 . . . . . . . . . 3.386 50 169 XI No. 31 . . . . . . . . . . . . . . than the check variety SAFITA-102 in EVT 16B, and No. 12 . . . . . . . . . . . . . . only Across 7748RE yielded more than the check in No. 1 7 . . . . . . . . . . . . . . EVT 16A, although i t should be noted that SAFITA- No. 40 . . . . . . . . . . . . . . 102 was the latest maturing variety in both trials. No. 70 . . . . . . . . . . . . . . In addition to these two trials, high quality protein No. 21 . . . . . . . . . . . . . . materials developed by CIMMYT were tested in the No. 47 . . . . . . . . . . . . . . trial QPMT 11B a t Kamboinsb. Eight high quality Checks: protein varieties, along with three checks (normal), SAFTTA-104 . . . . . . . . . were tested. There were no significant differences in Pool-27 . . . . . . . . . . . . . TZUT. . . . . . . . . . . . . . . yield among the varieties tested. Pool-34 QPM (RSF) TZPR . . . . . . . . . . . . . . . was found to be most promising not only in yield, but in stability of modifiers for hard endosperm. Seed of 40 Cereals far, data from 12 countries have been received for leaf margins a t night and in the day hide in and feed RUVT-1 and from 6 countries for RUVT-2. on the whorls. On adult plants the caterpillars feed The results for RUVT-1 are as follows. In on the silk and after cutting it penetrate the cob. Cameroon TZESR-W, Temperate x Tropical No. 42, Infestation is usually more serious a t the whorl Pirsabak (1) 7930 and SAFITA-104 were promising stage. This year it was very low on both varieties in varieties. SAFITA-104 was seven to eight days earlier D l throughout the growing period. But in D2 i t was in days to flower. In Guinea TZESR-W, Pirsabak (1) 2.5.l and SPV35), but zone, Poca Rica 7843 gave the highest yield, while were very tall and late in maturi ty. Th e entri es were Samaru 123 and Garoua Flinty white and the local also susceptible to gray leaf spot (Cercospora sorghi), checks, which are recommended and extensively oval leaf spot (Ramulispora sorghicola), sooty stripe grown, gave the lowest yields (T ables 54 and 55).­ (Ramulispora sorghi), zonate leaf spot (Gleocer· T.G. Hart , J. Kikafunda·Twine and H. Talkyrand cospora sorghi) a nd a n thracnose (Colletotrichum Table 57. Yield and agronomic characters of entries in the pearl millet African regional yield trial from ICRISATIIAR (Zaria), Maroua, Cameroon, 1982 Plant Panicle Disease reaction' Yield, Days to 50'jb height, length, Downy Entry kg/ha flowering cm rm mildew Ergot Smut INMLI1253 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.625 51 255 35 0 1 I LNMR 40 NC x IVSPT . . . . . . . . . . . . . . . . . 4,542 INMR2053 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.542 JNMB 3253 F . . . . . . . . . . . . . . . . . . . . . . . . . 4,333 INMR 70 MSA . . . . . . . . . . . . . . . . . . . . . . . . 4,292 INMB 72VE2F.. . . . . . . . . . . . . . . . . . . . . . . . 4.125 INMR 37 S F, .'. . . . . . . . . . . . . . . . . . . . . . . . INMB 4 MAS . . . . . . . . . . . . . . . . . . . . . . . . . INMB 46 S3 EVAL. . . . . . . . . . . . . . . . . . . . . 3,979 INMR33S,F, . . . . . . . . . . . . . . . . . . . . . . . . . 3,937 KDMC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.792 INMRBC,F, . . . . . . . . . . . . . . . . . . . . . . . . . 3,652 INMB 74 MSS . . . . . . . . . . . . . . . . . . . . . . . . 3,313 INDIARI (local). . . . . . . . . . . . . . . . . . . . . . . 2,667 MOUKI (local). . . . . . . . . . . . . . . . . . . . . . . . 2,271 Grand mean . . . . . . . . . . . . . . . . . . . . . . . . . . 3,874 LSD (5%,). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 868 C.V..% . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 "Disease reactLon was rated on 0 to 5 scale, wherc 0 = resistant. I = 1 to 10% incidencc, 2 = 11 to 20%,, 3 = 21 to 35'>:,, 4 = 36 to 50Yo a n d 5 = over 50% graminicola). The top five yielders arc listed in Table panicles and white, hold grain type, and wcre 56. Of the 134 lines assessed in the other two resistant to leaf spots, grain mold and stem horers. experiments, 14 were found t o he superior to the Of the 109 grain mold resistant crosses from improved local checks (CE 99 and IltAT 55) in yield ICRISAT, Hyderahad, 26 were selected on the hasis of and resistance to diseases and pests. high yield, early maturity, medium height. semiloose, longvanicles, and resistance to grain mold, leaf spots Evaluation of Introduced Germplasm ands t em borer. In another experiment none of the 15 lines introduced from Sudan were found t,o he A total of 223 sorghum lines, crosses and breeding adaptable to the conditions of northern Cameroon. materials comprising introductions %om Centre Similarly, all the 16 accessions from CNRA, Bamhey. National de la Recherche Agronomique (CNRA), were found t o he inferior to the check variety (IRAT Bamhay (Senegal); t he All-India Coordinated 55) i n yield and other desirable agronomic 'harac- Sorghum Improvement Project (AICSIP); t he ters, and none of the eight introductions from International Crops Research Institute for the Semi- AICSIP outyielded the local checks. Arid Tropics (ICRISAT), Ouagadougou (Upper Among the 55 introductions from TCRISATIIAR. Volta); ICRISAT, Hyderabad (India); and ICRISAT/ Zaria, which were evaluated in two experiments, Institute of Agricultural Research (IAR), Zaria nine entries outyielded the hetter local check (IRAT (Nigeria), were evaluated in 19 different experiments 55) and were also better in characters such as early during t,he 1982 rainy season a t IRA'S Guiring maturity, medium height, long, semiloose panicles, Research Station, Maroua. The purpose was to good grain quality, and resistance to stem borer, gray identify adapted materials with high yield and leaf spot and zonate leaf spot. Thcy were, howcvcr. resistance to the major diseases and insect pests. susceptihle to anthracnose. IRAT 55 and CE 99 were used as t he local checks in In the international preliminary varietal yield most of the experiments. trial from ICRISATIIAR, Zaria, 28 entries, including In one trial 26 entries, including two checks, were two hyhrids and six local varietics, were evaluated. evaluated. Yolohri, a local entry, did not flower until Entries S-35 (8,028 kg/ha), S-32 (7,194 kg/ha) and 8-38 the experiment was harvested. Damougari, another (7,028 kg/ha) were very promising in yield, early local entry, gave the highest yield, followed by maturity, panicle length, grain quality and re- M-36056, M-36121, IS-115 and IS-10023 (Table 56). sistance to stem borer and leaf spots but were Damougari was observed to be early in maturity and susceptihle to anthracnose (Tahle 56). The two medium in height but had short and compact panicles hybrids, CSH-6 (5,583 kg/ha) and CSH-5 (4,999k g/ha). with red. medium sized grains. Two of the entries, performed poorly compared with the open-pollinated M-36056 and M-36121, were found to he promising; varieties, ranking fifteenth and twentieth, they were medium in height, had long, semiloose respectively. 50 Cereals Evaluation of Dry Season Cultivars Work was begun on dry season sorghum by establishing 57 Muskwari (dry season sorghum) entries collected by IRA and 52 entr ies from ICRISATIIAR, Zaria, in observation nurseries. They were transplanted during the first week of October 1982 :it the IRA Sarlak Research Station near Maroua. Data will be collected on adaptation characteristics, yield potential and other desirable agronomic characters. Pearl Millet Yield Trials Three experiments, t he pearl millet exchange nursery from ICRISAT/CNRA, Maradi (Niger), and two pearl millet African regional yield trials from ICRISATICNRA, Maradi. and ICRISATIIAR, Zaria (Nigeria), were planted to assess their performance under the conditions in Cameroon. All 10 test entries in t he exchange nursery trial were lower yielding than the local check (IDIARI) but were earlier in maturity; two of them (ITV 8001 and CTV) wrrc also tolerant to downy mildew, ergot and smut. In the African regional yield trial from ICKLSAT/IAK, Zaria. all 13 entries were higher yielding than the two local checks, IUIARl and MOURI (Table 57). None of the 12 entries evaluated in the African regional yield trial fkom ICRISATI CNRA, Bambey, was higher yielding than the two localchecks (IDLART and MOURI), althoughmany of them were tolerant to downy mildew and e r g o t . - ~ ~ ~ O.P. 1)angi Grain Legumes 53 T HE G R A I N I.EGUME IMPROVF:MENT PROGRAM deals A major effort was made this year, through a staff with two crops, cowpeas, for which IlTA has position created for a project in northern Nigeria international responsibility, and soybeans, for (Zaria) that is being funded by the European which i t has regional responsibility in Africa. Economic Community, to identify and develop Cowpeas originated in West Africa but are now resistance to three major cowpeadiseases-~Septoria, common in many other parts of the continent. They scab and brown pod blotch-which are predominant are also cultivated under marginal moisture and poor in the traditional cowpea growing areas of the Sahel soil conditions in Asia and South and Central and Sudan savanna. Our advanced material has not America. Cowpeas are an extremely important previously had resistance to these diseases. Through source of plant protein for the poorest of the world's screening for resistance in northern Nigeria, a few poor. Soybeans, although they are not cultivated as lines have been identified that combine resistance to extensively in Africa as are cowpeas, have enormous these diseases with good agronomic characters. potential for expanded production and could do IITA scientists working in the Semi-Arid Food much to help meet the growing demand for vegetable Grains Research and Development (SAFGRAD) oil and for both human food and animal feed. Project in Upper Volta have identified two cowpea To help farmers boost cowpea production, the cultivars that are resistant to Striga (commonly Grain Legume Program is developing varieties with known as witchweed), which is causing considerable good seed quality, resistance to insect pests and yield losses in the Sudan savanna of West Africa. A diseases, and different maturity periods to fit the hybridization program was begun a t Kamboinst., various ecological zones of the tropics. In soybean Upper Volta, to incorporate Strig.a resistance into research primary emphasis i s placed on seed advanced lines. storability, compatibility with indigenous rhizobia Several cowpea varieties developed a t IITA or its and yield capability. Genetic improvement of both re e, ional stations were multinlied and released to crops is reenforced by soil microbiology research, farmers this year through national programs in which so far has focused primarily on increasing several countries. The variety TVx 3236, for example, yields through biological nitrogen fixation. which was released to farmers last year, is now being multiplied on a large scale. In Kano State alone, in Cowpeas northern Nigeria, farmers plan to multiply this variety in 500 villages on about 5,000 hectares under During IITA's first decade of cowpea research, a the supervision of the Kano State Agricultural and major effort was made to develop improved plant Research Development Authority. If well managed types and to identify sources of resistance to insect the seed should be sufficient for planting 0.5 million pests and diseases. In recent years we have hectares next year. concentrated on combining insect and disease After extensive tests the Ministry of Agriculture in resistance with improved plant type and on the South American country of Guyana has developing extra-early maturing cowpeas. recommended four IITA cowpea varieties to farmers. These efforts are beginning to pay off. For the first These varieties, ER-7, TVx 66-2h, TVx 2907-02D, and time, resistance to the cowpea storage weevil VITA-6, have been named Minica I, 11, 111 and IV, (bruchid) has been incorporated into cowpea respectively. In Brazil IITA cowpea varieties VITA-3 cultivars with superior agronomic characters. and VITA-6 were released as EMAPA 822 and 821 by Bruchids are causing enormous losses throughout the Maranhao State Enterprize for Agricultural the world. In Nigeria alone the losses are estimated Research, Empressa Brasiliera de Pesquisa Agro- to be over $30 million a year. Improved bruchid pecuiria (EMBRAPA) and National Center for resistant lines are now being sent to cooperators in Research on Rice and Beans (CNPAF). IITA varieties about 40 countries for evaluation of yield and have had a significant impact on cowpea production bruchid resistance. in Brazil. In recognition of this contribution, IITA IITA has also developed extra-early cowpeas that was recently awarded with a trophy from EMBRAPA mature in only 60 days and have acceptable seed and CNPAF. quality. An international trial of nine extra-early cultivars with variable seed quality is being Genetic Improvement distributed to over 40 countries. These varieties should fit well into the cropping systems of various The cowpeas grown in West Africa are specifically ecological zones. They should be particularly adapted to the environments and cropping systems in suitable in areas such as the Sahel and Sudan which they evolved. Characteristically, they are of savanna that have a very short rainy season and in indeterminate type, with a spreading growth habit the lowland humid tropics after the main rice crop, and maturity period of up to 150days. In most parts of when the land is normally left fallow and no other West Africa, large, white, rough seeded cowpeas are crop can be grown. preferred, although several other varieties with 54 Grain Legumes different seed characteristics are also cultivated. In ecological zones. Lines selected from the preliminary many other parts of the tropics, specifically Asia and trials form advanced trials. The international trials Latin America, brown, red and black seeded varieties consist of materials selected from the advanced trials are cultivated in addition to the white ones. and are sent to cooperators in more than 40 countries The major objective of the cowpea breeding around the world. program at IlTA is to develop improved cowpea varieties that are suited to the environments in Pre l iminary yield tr ials . These trials were which cowpeas are grown. These varieties must have conducted a t IITA and two other locations in wide adaptation, acceptable seed types, resistance to Nigeria, Mokwa and Samaru. The trials consisted of diseases and pests, improved plant type and high lines selected from F5/F6 entries that were evaluated yield potential. Toward that end, several early and in 1981. Some of these materials possess high levels of advanced generation lines were evaluated in a series resistance to several diseases and have good seed of trials a t several locations in Nigeria that represent quality. A total of 126 lines were evaluated a t each the forest, Guinea savanna and Sudan savanna location. Each trial had a random block design, with zones. International trials were sent to 40 different four replications and a plot size of four rows 4 m long. countries for evaluation of yield and pest resistance. Ife Brown, VITA-7 and TVx 3236 were included as check varieties. Twenty-five lines performed as well or better than H y b r i d i z a t i o n and E a r l y Generation the check varieties. The most promising of these were M a t e r i a l s TVx 3236-5-2, IT81D-1186, IT81D-1202, IT81D-1148, A total of 350 different types of crosses were made IT81D-1205 and IT81D-1032. The mean yield of these during the year involving parents of different lines was over 1,700 kg/ha, compared to 1,350 kg/ha maturity groups, with disease and insect resistance for the checks. and with desirable seed quality. Fip lants were grown Advanced yield trials. The three advanced yield in the greenhouse. In addition, 110 F2 populations, trials were also planted at IITA, Mokwa and Samaru 279 FY,4 0 Fq and 56 F5/Fs populations, comprising in Nigeria. Advanced trial 1 consisted of 17 entries several thousand progenies from the previous year, and three check varieties. Ife Brown, VITA-7 and were evaluated, and desirable individual plants/ TVx 3236. These entries were of the medium maturity progenies were selected. These are again being group (75 to 85 days), varied in seed color and for the grown in the dry season for generation advance. most part had smooth testa. There was no significant Several advanced breeding lines are available that diEerence between their yield and that of the checks possess resistance to one or morediseases, along with a t IITA and Mokwa. However, a t Samaru four lines individual resistance to thrips, aphids and bruchids. appeared to he superior to the check varieties. In Efforts are now being made to develop varieties that advanced trial 2, which consisted of early maturing combine multiple disease and insect resistance. A lines (60 to 65 days) with desirable seed characteris- generalized breeding strategy for developing tics, one line significantly outperformed the checks multiple disease and insect resistant lines has been a t Samaru. There was no significant difference in developed. By using the greenhouse and dry season advanced trial 3 between the yield of the top lines, nurseries, four cowpea crops can be grown every which combined hruchid resistance with desirable year, and within two years one cycle of recom- agronomic characteristics and seed type, and that of bination and pedigree selection for disease and insect the check varieties (Table 1). resistance and yield can he completed. The promising lines can he recrossed for another cycle of recom- Internat ional Trials. Varieties selected from bination and selection until the desired level of advanced trials in 1981 hecause of their yield resistance to diseases and insects is achieved. potential and resistance to diseases were included in Several crosses involving donor parents with two cowpea international trials this year. Inter- thrips resistance (TVx 3236), aphid resistance (TK- national trial 1 consisted of 9 white seeded varieties 1R). hruchid resistance (IT 81D-1137 and IT 81D- and international trial 2 of 19 varieties with red, 1064),e arly maturity (IT 823-60) and multiple disease brown or cream colored seed. Each trial had a resistance (TVx 1850-01E, TVx 4659.033, etc.) were complete randomized block design with four repli- made. A systematic backcrossing program was also cations and a plot size of four rows 4 m long. In each initiated to incorporate multiple disease resistance trial the national improved variety was included as a and aphid and hruchid resistance into TVx 3236 and local check. Over 90 sets of trial I and 82 sets of trial other advanced l ines . B.R. Ntare and B.B. Singh 2 were sent to 40 countries around the world. The yields of the varieties in international trial I a t V a r i e t y t r i a l s 10 locations are listed in Table 2. The yields in trials located outside Nigeria, which were supervised by In the cowpea variety trials, lines from the F5 national scientists, were generally low a t all generation and beyond are tested in threestages. The locations. TVx 3236 gave the highest overall yield. first is preliminary yield testing, which is carried out Other lines that performed well were TVx 4659.033, at locations in Nigeria that represent different VITA-5 and TVx 4662-09D, which combine good seed Grain Legumes 55 quality with disease resistance. TVx 4659.033 has Table 1. Performance of IITA cowpea lines in strap leaves and medium maturity and is resistant to advanced yield trials a t various locations in cowpea yellow mosaic, cowpea aphid borne mosaic, Nigeria, 1982 anthracnose, bacterial pustule, bacterial blight, Yield. kg/ha brown blotch, Septoria and Cerospora leaf spot. Iine IITA Mokwa Samaru Mean For international trial 2, data are available only from seven locations; the mean yields of the varieties Advanced trial 1 are listed in Table 3. TVx 4678.0883 and TVx 4678- TVx 4664.0443 . . . . . . . . . . 1,192 1,899 2,307 1,799 03E TVx4659-05E . . . . . . . . . . . 1,406 1,565 2,296 1,755 gave the highest yields and were consistently TVx 4678~033.. . . . . . . . . 1,192 1,941 2,012 1.715 superior to other varieties at most locations. Both of TVx4662-073.. . . . . . . . . . 1,273 1,189 2,115 1.526 these lines are resistant to several foliar diseases.- B.B. Singh, B.R. Ntare and Ren~Ai deleke Check varieties: Ife Brown . . . . . . . . . . . . 1,035 1,044 770 950 Extra-Early Varieties VITA-7 . . . . . . . . . . . . . . .1 .454 1,670 1,737 1,620 TVx 3236. . . . . . . . . . . . . 1,124 1,837 919 1,293 A systematic program was begun to develop extra- LSD (5%,) . . . . . . . . . . . . . . 427 425 454 early cowpea varieties that fit in multiple cropping C . V . , % . . . . . . . . . . . . . . . . 26.8 18.3 18.4 systems and perform well in low rainfall areas of the tropics. A number of varieties selected from different Advanced trial 2 1T81D~1157 , , , , , , , , , , . . , ,22X ,750 2,129 2,036 segregating populations as well as germplasm were TV, 5592.0C.. . . . . . . . . . .1 ,424 2,594 1,795 1,938 evaluated for yield and other characters a t different I T ~ I D - I .I.~. .~. . . . . . . . . 1,130 1,828 1,701 1,553 locations in Nigeria. Fifty-five planned crosses were TV, 5054.010~. . . . . . . . . . 1,279 1,766 1,609 1.551 made between extra-early varieties and sources of ITRID-1064.. . . . . . . . . . . 1.153 1.766 1.701 1.540 disease and insect resistance. A hackcrossing pro- Check varieties: gram was also begun to systematically incorporate Ife Brown . . . . . . . . . . . . 1,205 2,375 1,534 1,705 resistance to different diseases and insects into VITA-7. . . . . . . . . . . . . . .1 ,176 2.016 1,766 1,653 selected extra-early varieties. TVx 3236.. . . . . . . . . . . . 1,014 2,516 977 1,502 The most promising early maturing varieties, selected on the basis of earliness, yield potential and LSD (5%,) . . . . . . . . . . . . . . 358 588 408 CV,, % - , , , , , , - ,, , , , , - - 20,7 20,8 18,6 disease resistance, were evaluated in two different trials. Early maturity trial 1 consisted of 20 varieties Advanced trial 3 that matured within 60 to 6 5 ,jayasn d early maturity IT81D-1052 . . . . . . . . . . . . .1 ,450 1,587 1,865 1,634 trial 2 of 20 varietiesth at required 70 to 75 days to IT81D-1031 . . . . . . . . . . . . . 1,299 1,785 1,642 1,575 mature' Ife Brown was as a check. Both of IT81D-1007 . . . . . . . . . . . . . 1,358 1,795 1,169 1.441 IT81D.1()!20 , , , , , , , , , , , , , 1,423 1,430 1,528 1,467 these trials were conducted at 'ITA, Mokwa and IT81D-1036.. . . . . . . . . 1 ,348 1,722 1,099 1.390 Samaru, which represent different ecological zones in Nigeria. Check varieties: The mean yields of the best six varieties from the Ife Brown . . . . . . . . . . . . 894 1,451 1,530 1,292 extra early group and those of the early maturity VITA-7 . . . . . . . . . . . . . . .1 ,310 1,503 1,433 1,415 TVx 3236.. . . . . . . . . . . . 1,139 1,701 1,155 1,332 group are listed in Table 4. During the second season at IITA, the varieties generally performed poorly LSD (5%) . . . . . . . . . . . . . . 316 354 576 because of extreme drought and poor germination. C.V., . . . . . . . . . . . . . . . . lg4 17.1 Table 2. Mean yields of cowpea varieties in international trial 1,1982 Yuri- IITA, Nigeria ~ ~ skam. a~ Mala- Nyan- Moga- Chung- maguas, Kila, First Second wa, Ni- ru, Ni- Kano, maduri, kpala, dishu, huk, Variety Peru Nigeria season season geria geria Nigeria Nigeria Ghana Somalia Korea Mean &/ha TVx 3236 . . . . . . . . 1,423 1,280 900 672 1,868 772 1,827 459 1,090 334 1,602 1,107 TVx3627-012F_ 1,025 753 972 609 1,190 1,086 1,200 919 885 132 1,183 905 TVx 3671-7C-02U . 1,218 1,350 629 683 1,096 877 1,415 522 468 409 272 813 TVr 3671-14C-01U. - 1,409 323 690 981 518 1,566 522 363 361 487 722 TVx4262-09D . . . . 1,270 968 1,040 753 825 1,488 1,639 585 380 330 928 TVx 4262-014D . . . 1,280 572 327 1,326 789 1,378 480 864 322 1,028 837 TVx 4659-03F.. . . . 1,383 1,992 1,253 650 835 714 1,983 334 601 274 - 1,002 Local check. . . . . . 1,088 -~ 467 1,921 -- 549 877 231 301 519 744 Standard checks: VITA-5.. . . . . 1,303 1,482 554 781 1,211 1,065 1,962 605 378 289 872 955 IfeBrown . . . . . . 1,073 1,322 553 691 1,246 643 2,104 ,522 714 302 967 9'22 LSD (5%,).. . . . . . . 287 368 437 206 495 386 837 371 440 208 383 C.V., "/,. . . . . . . . . . 16 19 40 22 27 30 37 44 50 47 30 56 Grain Legumes Table 3. Mean yields of cowpea varieties in international trial 2,1982 IITA, Nigeria First Second Mokwa, Mogadishu, Chungbuk, Nyankpala, Yurimaguas, Samaru, Variety season season Nigeria Somalia Korea Ghana Peru Nigeria Mean &/ha VITA-7. . . . . . . . . . 1,578 795 1,503 325 1,128 1,505 1,663 1,336 1,229 TVu 3629.. . . . . . . 817 721 1,326 165 876 1,008 1,430 710 882 TVx 1836.0135 . . . 976 921 1,378 298 419 1,142 1,477 731 918 TVx 1948-01F . . . . 1,434 910 1,795 397 515 1,407 1,580 1,253 1,161 TVx 133-16D-2 . . . 1,229 615 1,336 217 334 1,111 967 731 817 TVx 2394~02F. . . . 1,606 962 1,388 284 1,134 994 1,673 752 1,100 TVx 2724-01F . . . 1,171 838 1,242 410 696 1,244 1,610 835 1,006 TVx 3381-02F.. . . 1,175 936 1,472 914 539 1,033 1,543 1,023 1,079 TVx 3410-OW . . . . 929 863 1,837 520 387 1,136 1,597 1,148 1,052 TVx 3627-03G . . . . 1,131 870 1,639 251 1,238 1,413 1,503 1,378 1,178 TVx 3871-02F . . . . 967 828 1,232 285 506 624 1,410 877 841 TVx 4577-02D.. . . 1,241 792 1,346 91 929 1,816 1,830 1,420 1,183 TVx 4661-07D. . . . 935 841 1,461 376 1,047 994 1,703 1,253 1,076 TVx 4677-088E . . . 1,975 1,019 1,931 46 1 730 1,440 1,826 1,691 1,3R4 TVx 4678-03E . . . . 1,275 730 2,025 579 1,052 1,893 1,450 1,357 1,295 Local check . . . . . - 645 2,035 827 980 1,432 1,450 ~- 1,228 LSD (5%) . . . . . . . 569 215 506 235 824 509 258 855 C.V.,% . . . . . . . . . 33 18 23 41 74 28 10 36 But overall, the early maturing varieties yielded as IT 823.60 and IT 823-77, which were just as well or better than Ife Brown, even though the susceptible to brown blotch and cowpea yellow difference in maturity was more than two weeks. mosaic as Ife Brown. Most ofthe extra-early varieties matured in 60 and 65 The early maturing varieties vary in seed coat days, whereasife Brown matured in 77 to 85 days. All color. IT 833-32 has a red seed coat, IT 823-9 has a the early maturing lines had a moderate to high level black one, that of IT 823.5 is brown, and IT 823-56, IT of resistance to several diseases, except for IT 823-56, 823.60 and IT 823.77 have large, white seeds with a rough seed coat. Most of the varieties in early Table 4. Mean yield of extra-early and early maturity trial 2 had brown seed coats, except IT 823- maturing varieties a t various locations in 17, which has dark red seeds. Nigeria, 1982 Preliminary tr ials of these early maturing IITA varieties, conducted a t Onne in southern Nigeria, First Second gave very encouraging results. The trials were Variety season season Mokwa Samaru Mean planted in rice fallows on 28 October 1982 after the Early maturing trial rice crop was harvested. The residual moisture 1 &/ha IT82E~32. . . . . . . 1,961 1,143 2,109 1,809 1,755 supplemented with occasional showers was enough IT82E-9.. . . . . . . 2,003 978 2,078 1,614 1,668 for a successful cowpea crop. All the varieties TT82E-56 . . . . . . . 1,810 1,713 1,875 1,049 1,612 matured within 60 days, and the trials were ready for IT 82E-5.. . . . . . . 1,420 1,074 1,845 2,018 1,590 harvest by the last week of December 1982. The yields IT 82E-77 . . . . . . . 1,285 1,594 1,559 1,479 ranged from 600 to 1,300 kg/ha; the best varieties IT 82E-60 . . . . . . . 1,374 - 1,563 1,127 1,369 were IT 823-32, 823.4, 823-18, 823-32 and 823-56. Ife Brown (stan- These varieties will be further evaluated in the dardcheck). . . 2,151 1,205 1,484 1,264 1,526 coming season a t various locations. LSD (5%). . . . . . . 428 At present, no crop is grown in this region after C.V.,9/,. . . . . . . . . 21 rice harvest. The results reported here indicate that Early maturing trial 2 early cowpea varieties could be successfully grown IT 823-16 . . . . . . . 3,023 on residual moisture after rice. This double cropping IT 823-18 . . . . . . . 2,444 system could be of immense economic importance to TT 82E-25 ....... 2,016 farmers. Not only would it give them extra income IT 82E~3. . . . . . . . 2,207 and enable them to make better use of their land and IT 82E-12 . . . . . . . 1,972 labor, but it would also provide them with more IT 823-17 . . . . . . . 2,042 nutritious diets. Ife Brown (stan- dard check) . . . 2,441 Bush Type Vegetable Cowpeas LSD (5%). . . . . . . 531 C.V..% . . . . . . . . . In several countries of Asia cowpeas are grown for 18 their long, fleshy, tender pods, which are used as a 58 Grain Legumes advanced breeding lines have been developed that Table 7 along with data on TVu 2027 and some combine hruchid resistance with high yields, disease susceptihle varieties, including Ife Prown and TVx resistance and good seed quality. 3236. Emergence of bruchids in the resistant lines A number of these lines were evaluated in wasdelayed and staggered, and fewer adults emerged multilocational trials during 1982. The mean yield than in the susceptible lines, in which a large number and level of hruchid resistance of t,he most promising of adults emerged early and quickly. lines, which vary in seed color, are listed in Table 6. TVu 2027 was originally collected from the Rima The lines that showed higher yield potential than Ife Valley of Sokoto State, which is about 1,000 miles Brown a t all locations, IT 81D-1157, 81D-1148, 81D- east of the Gombe area. For that reason and because 1032,81D-994 and 81D-1007, also proved to be just as the pod characteristics of TVu 2027, KNW (TVu hruchid resistant as TVu 2027 and even better in 11952) and KNS (TVu 11953) are quite different,t hese disease resistance. These lines also have desirable resistance sources may be of independent origin. seed quality t,hat is acceptable in different regions. IT Genetic studies have been initiated to ascertain 81D-985 and IT 81D-992 have large white seed with a whether the genes for resistancein these lines are the rough seed coat; IT 81D-1157 and IT 81D-1148 have same or not. As is apparent from Table 7, the level of tan seed; that of IT 81D-1032 and IT 810-1064 is red, resislance in these lines is only moderate and cannot and IT 8113-1137 has white seed with a smooth seed provide complete protection under severe infestation. coat. Seed of these lines has been multiplied for The inheritance of bruchid resistance was studied distribution to various national programs in 1983. in nine populations, in which TVu 2027, KNW and Two new sources of resistance to hruchids were KNS as resistant parents were crossed to several identified this year. They were selected from the local susceptihle parents. Data from F,, F2 and hackcross variety Kanan Nado, which was obtained from the populations indicate that two recessive gene pairs Gombe area of BauchiState, Nigeria, courtesy of J.G. are required in the homozygous condition forhruchid Quinu. Thc bulk sample had white and speckled seed, resistance, and a typical ratio of 15 susceptible to 1 which was sorted and bioassayed separately for resistant plant was observed in F2. Data from one of hruchid resistance. Both samples, now maintained as the crosses, TVu 2027 x TKx 133-16D-2, are Kanan Nado White (KNW, TVu 11952) and Kanan presented in Table 8 , and the frequency distribution Nado Speckled (KNS, TVu 11953), were found to he in different populations of the same cross is shown in just as resistant as TVu 2027. Data on the level of Figure 1. The F1 seeds behaved just like the maternal bruchid resistance in these lines are presented in parents. FZs eeds were susceptible, irrespective of the Table 5. Performance of vegetable cowoea varieties. IITA. 1982 Pod Moisture Percent protein in: Dry seed Grcen pod length, content in Green pods Variety yield. kg/ha yield, kg/ha cm green pods, %, Fresh Dry Seeds LT 8lD-1228-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,312 18,913 25 89.5 2.94 28 24 IT 8111-1228-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 776 16,778 29 89.3 2.78 26 25 IT810~1228-15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 888 15,468 28 89.6 2.91 28 26 TVx 3442-273. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 982 14,767 32 89.3 2.78 26 25 FARV-13(check). . . . . . . . . . . . . . . . . . . . . . . . . . . 555 12,504 31 89.1 2.73 25 26 LS0 (5%,) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604 3,356 C.V .. % . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 1:i Table 6. Performance of bruchid resistant breedine lines a t various locations in Nigeria. 1981 IT 81D-1157.. . . . . . . . . . tan 1,336 1,228 2,750 2. IT 810-1148. . . . . . . . . . . tan 1,453 IT 81D~l032.. . . . . . . . . . red 1,489 IT 81D-994. . . . . . . . . . . . white IT 81U~1007. . . . . . . . . . red 1,291 IT 81D-1064.. . . . . . . . . . red 1,604 IT 81D-1137 . . . . . . . . . . white 1,433 IT 810-985. . . . . . . . . . . . white Ife Rrown . . . . . . . . . . . . hrown 918 TVu 2027. . . . . . . . . . . . . white - ~~ LSD (.5.%. .). . . . . . . . . . . . . 516 V , ' . . . . . . . . . . . . . . 38 "Days after infestation. Grain Legumes 59 Table 7. Bruchid emer-ee nce in res~ista-n-t, a~nd- ~-- . Table 8. Segregation pattern for bruchid resistance susceptible parents, 1982 in TVu 2027 x TKx 133-16D-2. IITA. 1982 NO.~ ~no. tPatte~rn ofl adul t emergence Number of plants: of of'adults 27-32 33-38 39-44 45-50 Rio- Resis Susrep~ Accession eggs emerged DAIS DAI OAT UAI Population assayed tant liblc ~2 TVu 2027 . . . . 30 7 0 3 2 2 TVu 2027 (P,) . . . . . . . 39 39 TVu 11 952 TKx 133-16D-2( P2). . 40 - 40 ~ ~- (KNW) . . . . 36 TVu 11953 F2 seed (from F1). . . (KNS) . . . . . 30 TVu 2027 x TKx Ife Brown. . . . 35 333-1611-2 (F,) . . . . . 19 TKx 133-16D-2 34 TKx 133-1611-2 X Cross l~l6F: . . TVu 2027 (RF,) . . . . 36 - 32 36 TVx 3236 . . . . 33 FS seed (from F,) "Days after infestation. TVu 2027 x TKx 133-16D-2( Fe) . . . . . 33 1 33 (lK.15S) maternal parent, and represented the true hybrid TKx 133-16D-2 x 0.361 phenotype, indicating maternal control of bruchid TVu 2027 (RF,) . . . . 76 6 70 (1R:lSS) resistance as well a s complete dominance of Backcross ( F ps eed) 0.143 susceptibility. The pooled F2 population (F3 seeds Fl x Pl:Bl . . . . . . . . . 21 6 15 (1K::jS) from F2 plants) segregated into 102 susceptible and 7 Fl x P,:B, . . . . . . . . . 66 66 resistant plants, fitting the 15:l ratio closely. Similar results were obtained in reciprocal crosses. The backcross population towards the resistant Number of plants parent segregated into 15 suspectible and 6 resistant plants, which i s a ra t io of approximately 3 susceptible to 1 resistant plant. The other backcross population, involving a susceptible parent, was completely susceptible as expected. The frequency distribution (shown in Figure 1) showed a similar trend and supported the genetic data. The results from all other crosses were similar and confirmed the digenic inheritance of bruchid r e s i s t ance . B.B. Singh, S.R. Singh, 0.A djadi and B.R. Ntare. Aphids. Aphids are a major problem in cowpea cultivation; not only do they reduce yield directly, hut also indirectly by transmitting virus diseases. Breeding for resistance to this pest is one of themajor objectives of IITA's cowpea improvement program. Several sources of resistance have been identified, and a number of crosses have been made to combine high yield potential and disease resistance with aphid resistance. Screening of several hundred germplasm lines of cowpea revealed a number of lines with a high level of resistance and verified sources of resistance reported previously, including: TVu 18 109 801 3000 9929 36 310 1037 3273 9930 Percent adult emergence 42 408 2755 9836 9944 62 410 2896 9914 Figure 1. Frequency distribution of percent hruchid emergence in differentp opulations of the cross TVu 2027 x When aphids are infested on resistant cultivars, they TKx 133-16D-2a t 33 days after infestation, IITA. 1982. die within 24 hours, indicating that antibiosis is the mechanism of resistance. all the crosses segregated in a ratio of three resistant The genetics of aphid resistance was studied in five to one susceptible plant (Table 9), suggesting that crosses involving resistant and susceptible parents. inheritance of aphid resistance is monogenic. The resistant parent, TK-IR, was derived from the Twenty-five crosses were made between selected cross TK-1 x TVu 62. The F1 plants in all the crosses high yielding varieties and the aphid resistant lines were resistant, indicating complete dominance of TVu 3000, TVu 801 and TK-IR. The F1 and F2 resistance over susceptibility. The Fz populations of populations were screened in the greenhouse under Number of Moruca orvoe per 20 flowerr the population levels arc shown in ls'igures 3 and 4. 32 1 At IITA the first season population consisted mainly of Clal:igralla shad<,bi. During the second season, C. tomentosicollis accounted fc~r8 04:, of t he population, which was four timcs that of the first season. A t Mokwa t h e major species was C. lomcrltosicollis. which accounted f t ~ ral most 95'%, of t he pc~pulation. The ear ly popul:ition ronsistcd entirely of adults, suggesting n~igrar ionf rom an external source. But because t he insect breeds in t h r i--Frst season i+Second S e o r n i crop, thc population increased rapidly unt i l i t was Sornpl#nqd ote two times the IlTA population during the second Figure 2. Fluctuation in the population of Maruca on season. Extremely high populations were ohscrved monocropped VITA-7 at two locations in Nigeria, 1982. The about 56 days after t he crop was planted. vertical lines on the bars represent standard crrurs. These results indicatc tha t Mokw:~w ould he a good location for pod hug resistance screening. Further- milre, i t seems possihle t o avoid great damage t o the Tot01 number of bugs per 2-m of row crop either by planting earlier. (assuming normal 19--7 1 L 1 rainfall) o r using extra-early maturing cowpea varietics and thus avoiding the extremely high populations. The fact tha t pod bugs migrate into cowpea fields i n large numbers suggests t he existence of rescrvoir/altcrnatc hosts. This finding led to work on the host range of these pod bugs. In a survey for wild host plants of C. tomcntosico1li.s a n d C. shudehi between November 1981 and Dcccmhcr 1982, h'rioscma psoraleoides Hook (Papilionc~ceaejw as found to he the most common al ternate h i ~ s tp lant for C. tomentosicollis and C'. shadehi as well a s for othcr pod sucking hugs. namely Mi rpc rus j acu lus , Rip tor tus dent ipcs , Nezara uiridula, Pirzodorus guldinii, Anoplocncmis curoipes and Aspaoia sp. Although we did not determine whether this species is t,hc immediate source of Sornpl8ng dote initial infestations of cowFeas, i t did seem to play an Figure 3. Fluctuation in the population of'pod sucking hugs important role in the ecology of C. tomentosicollis by in VTTA-7, IITA, 1982. The numher in parentheses is thc total population sampled. hosting t he pest during par t of the dry season in the southern Guinea savanna (Mokwa) and in the derived savanna or t,ransition zone (Ogbomoshoj. Cassia mimosoides L. (Cuesalpinaceae) was Numberof bugs per 2-m of row ohserved t o be quite important a s a source of' infestation hy C. shadebi and othcr hugs. Other host plants t ha t were found t o host many pod sucking Adults ond nymphs hugs, hu t no t Clavigralla species, were Cassia /z=975/n rec/si occidentulis and Eriosema glomc,ratum. The life cycle of C. tomer~tosicollisw as affected hy i ts source of food when the insect was reared in the lahoratory, where the temperature varied between 21° and 27OC. As shown in Table 10, there was no significant difference i n t he duration of the first two ins ta rs Vigna unguiculata, Cajanus cajan and Eriosema psoraleoides. All the nymphs died during t he second instar when reared. on Crotalaria juncca, Cassia mimosoides and Cassia occidentalis. To investigate t he onset of pod sucking hug infestations in relation to time of planting and crop phenology, a planting da te trial was conducted a t Mokwa between May and November 1982. The dates Figure 4. Fluctuation in the population of pod sucking hugs of planting were 27 May. 24 June. 22 Ju ly and 19 at M o k w a , Nigeria, 1982. The number in parentheses is the August. The species composition is presented i n total population sampled. Table 11. C. tomentosicollis ;md (2. shadchi had t he 62 Grain Legumes Table 10. Effect of host plant on the development stages of C. tomentosicollis, IITA, 1982 Duration of' instars, (kS.E.) Host plant 1 2 3 4 5 IT.u nguiculnta.. . . . . 2.21(+_0.024) 2.67(+_0.211) 3.44(i0.266) 4.28(?0.2%) 5.90(*0.489) 18.50 C. cajan.. . . . . . . . . . . . . . 2.22(?0.187) 2.57 (k0.306) 3.40(?0.228) 4.00(+0.160) 5.63(i0.290) 17.82 E.ysornlcoides . . . 2 .17(?0.117) 2.90(?0.373) 3.73(+0.160) 4.7R(k0.556) 6.57(?0.605) 20.15 Table 11. Percent composition of pod sucking bugs a t various planting dates, IITA, 1982 Planting date N U ~ oDf b~ug~r p a mew row Pod hug 8 J u l y 6 Aug. 2 S e p t . 30 Sept.- species 19Aug. 16 Sept. 14 Oct. 11 Nov. Piezodorus guldinii . . . . . . . . 1.6 4.3 8.0 2.0 Clauigralla to- n~entosicollis. . . 0.6 0.9 45.08 83.0 Clauigralla shadnbi . . . . . . . . 77.1 44.7 9.2 0.0 Riptortus denfipes. . . . . . . . 0.8 14.0 2.8 0.0 Mirperus iaculus . . . . . . . . 13.1 9.8 14.3 4.0 Nezcra uiri- rluola. . . . . . . . . . 5.0 15.3 13.0 6.0 Anoplucncmis C L L ~ U ~ P L ' S. .. . . . . . 1.2 5.9 3.0 2.0 Aspauia armigera . . . . 0 6 8 10 12 14 1 6 0 6 8 10 I2 19 16 . . 0.6 5.1 4.7 3.0 No of hues Weeks offer plontlnq ~ ,~~ - ~~~ "- per meter" . . . 5.2 2.1 6.3 23.8 Figure 5. Changes in pr~pulationl evels of C. tomentosicollis "Highest number during eech sampling period. and C. shadehi a t different planting dates, Mokwa, Nigeria, "Mean for srven wrrks. 1982. highest population levels. The onset of C:. shadebi a t the F5 stage, were screened. At Mokwa 39 single was the earliest, occurring in July a t 56 days after plants were selected for Maruca resistance from F5 planting (Figure 5 ) . Although C. tamenlosicallis was progeny rows for further screening in replicated more devastating in its attack, not until the end of trials a t different locations. Anot,her 277 single plants September did a sudden outbreak of the species were selected from F:i progeny rows for further occur. The crop planted on 22 July was 70 days old testing. Also, work on the development of a pod borer and almost ready for harvesting. It thus escaped culture on artificial diet was continued. serious damage. Rut the crop planted on 19 August, In earlier reports we referred to the difficulty of suffered serious damage by C. tome~ttosicollis. getting pod borer adults to mate, which was These preliminary results appear to suggest that hindering progress in screening cowpea germplasm planting cowpeas by 20 July (or earlier if rainfall under artificial infestation. This year we achieved a permits) in the Mokwa area would most likely cause major success in obtaining a high percentage of the crop to escape high C. tomentosicollis infesta t 'i nn. consistent adult mating in a setup a t the exposed This conclusion needs fu r the r inves t iga t ion , basement of the entomology laboratory. These however . L.E.N. Jackai and W.N.O. Hammond studies, done in cooperation with scientists from other institutions. have shown that hieu h relat ~ ~i-v e ~ Insect Resistance humidity (80 to 100%) and moderately low tempera- tures (22' to 25'C) are essential for mating to take Pod bo re r s (Maruca). Using the field screening place (Figure 6). The level of mating also depends on method developed a t IITA (Annual Reports for 1980 the length of time for which males and females are and 1981), 1,000 cowpea cultivars from the world held to-e ether (, Fi-e ure 7). An averagu e of 305 REPS n ~ L , - .~er germplasm were screened for resistance to the female was obtained after five nights of pairing, and cowpea pod borer a t two locations, ITTA and Mokwa. moths lived for as long as 10 days. Females mated A total of 24 cultivars with 20'%, or less damage to only once, mostly between 0200 and 0300 hours. With pods were selected for further testing. In addition, this development appropriate bioassays for screen- ovcr 600 plant progenies, 433 a t the F:) stage and 254 ing will now be the main focus of our work. Grain Legumes 63 Pod bugs. The identification of sources for Temperature t0C) resistance to pod sucking bugs has been slow because of the species diversity, but our work during the past two years has shown clearly that C. tomentosicollisis 4 0 ~ the most important and damaging in the complex. Field populations are high enough to facilitate the screening of our germplasm. Forty cultivars, which were selected on the hasis of an earlier classification based on less damage by pod bugs, were screened a t two locations, Mokwa and IITA, under natural infestation. The evaluations were based on damage to seed. In the first season a t IJTA, TVu 6863 was the only cultivar for which mean seed damage was significantly less than that of the Humidity (%) susceptible check and that had a seed damage ratio of 0.3, compared to a ratio of 1 for the check, If'e Brown (Table 12). At Mokwa TVu 686'3 and TVu 1890 performed best in both plantings, although damage ratings were higher a t the second planting (Table 13). This confirms our suggestion in another part of this report that early planting or the use of extra-early maturing varieties would reduce damage by pod bugs. The data on insect numbers appears to suggest tha t , whereas TVu 1890 possibly possesses a I tolerance mechanism, TVu6863 may be exhibiting an O T ' ~ " " ' I 1 " " I antibiosis type of resistance mechanism. These 20 M 4 8 12 16 20 M 4 8 12 16 20 M points are being studied under controlled conditions Time (hr) in the lahoratorv. L.E.N. Jaclzai Figure 6. Optimum temperature and relative humidity for Maruca mating, TITA, 1982. TWO NIGHTS FIVE NIGHTS Average number of eggs per fernalez235; n = 2 0 Average number of eggs per female=305j n=50 Average longevity per female = 6.4 days Average longevity per female = 10.1 days 100 80 60 - 40 - $ 2 0 C 0 : 0 "3 0 .P- 2 THREE NIGHTS FOUR NIGHTS ? Average number of eggs per female=2174i n - 4 0 Average number of eggs per female=208.3, n=40 .- - Average longevity per' fermle = 6.9 days Average longevity per female = 8.1 days 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 Days after pairing Figure 7. Effect of pairing Maruca adults fur two, three, four and five nights on mating and oviposition, IITA. 1982. 64 Grain Legumes Table 12. Field screening of selected cowpea Table 14. Cowvea cultivars with resistance to flower cultivars for resistance to pod sucking thrips, IITA, 1982 bugs, IITA, first season, 1982 Days to Seed damage ratio first Kesis- Percent (test variety flow- tance Cu1tiv;lr seed damage to Ife Brown) Cultivar Pedigree cring rating" TVU6 863 . . . . . . . . . . . . . . . . . . . 25.5 TVu 7376. . . . . . . . . . . Ex-Tamale TVx 309-1G . . . . . . . . . . . . . . . . . 74.2 market 43 1.5 VITA~4. . . . . . . . . . . . . . . . . . . . 75.3 TVu 8154. . . . . . . . . . . Ex-Legon TVu 1890 . . . . . . . . . . . . . . . . . . . 86.0 collection 42 1.6 TVu 1846 . . . . . . . . . . . . . . . . . . . 89.5 1.02 TVu 4548. . . . . . . . . . . Ifc hvhrid TVu 1 . . . . . . . . . . . . . . . . . . . . . . 99.1 1.15 271-2 43 2.1 Tfe Brown (cherk). . . . . . . . . . . . 87.1 1.00 TVu 4544. . . . . . . . . . . Ife hybrid 113-1 43 2.2 Mean . . . . . . . . . . . . . . . . . . . . . . 76.8 0.88 TVu 6863. . . . . . . . . . . Kano 38 2.4 S.D . . . . . . . . . . . . . . . . . . . . . . . . . 29.2 0.28 TVu 4571.. . . . . . . . . . Ife hyhrid C.V.,%, . . . . . . . . . . . . . . . . . . . . 31.5 31.8 178-1 42 2.5 TVx 3236, TVu 1509 x Ifc resistant check. . . . hyhrid 62-1 42 2.6 Table 13. Pod bug counts and damage on selected (Ife Hrown) cowpea cultivars, Mokwa, Nigeria, 1982 VITA-? (TVx 289-4G). TVx 33-IH x Sccd No. of susceptible check. . TVx 29-28 43 4.6 Seed damage. %, damage rat id ,,f hugs LSD ( 5 % .~. . . . . . . . . 0.53 First Second First Second oer :im C.V., % , . . . . . . . . . . . . 14.60 Cultivar plant." plant.h plant. plant. oErowd =Resistanrer atings: 0 t,u 1 = highly resistant, 1 to 2 = resistant. TVu 1890 . . . 7.5 46.1 0.22 0.66 256.0 2 to 3 = moderately rrsistant, 3 to 4 = susceptible and 4 to 5 = VITA-4 . . . 22.2 i5.9 0.66 1.09 141.0 highly susceptible. TVu 6863. . . . 8.2 44. I 0.24 0.63 30.0 TVU 1846.. . . 33.2 68.3 0.99 0.98 81.0 VITA-6 . . . . . 42.3 74.2 1.26 1.06 201.5 Table 15. Damage caused by flower thrips on cowpea Ife Brown . . . 33.6 69.8 1.00 1.00 83.0 cultivars, IITA, 1982 Mean. . . 25. 1 60.5 0.75 0.87 116.4 Flower Reduct~onin LSU (5%) . . . 6.G 12.7 0.17 0.20 26.9 Cultivar ahscission, ' j: ~ o sdet . ' X , S.E . . . . . . . . . 4.0 4.0 0.12 0.13 21.3 TVu 1509. . . . . . . . . . . . . . . . . . . . . . 4.4 4.3 "l'irst planting was on 28 August 1982. TVx3236 . . . . . . . . . . . . . . . . . . . . . . 5.9 5.6 ''Second planting wltr o n 13 Septrmher 1982 lfe Rrown . . . . . . . . . . . . . . . . . . . . . 24.3 50.0 'Ratio ot'test variety to Ifc Krown. VITA-7 . . . . . . . . . . . . . . . . . . . . . . . 27.3 45.7 "Visual counts (fur second pli~ntingo nly). Thrips. In the past a t IITA cowpea germplasm During the second season, when t,he thrips popu- horn TVu 1 t o TVu 4000 has been screened for lation is high, these cultivars were tested in a resistancr to flower thrips Mega1urothrip.s sjostedti. replicat,ed trial and compared with TVx 3236 for Only two lines, TVu 1509 andTVu 2870, wcrefound to thrips resistance. Two cultivars appeared to have he moderately resistant to thrips; the rest were found greater resistance than TVx 3236 (Table 14). They to be highly susceptihle. In ficld tests, both lines were will be further tested next year in replicated trials a t often resistant under normal field populations, but several locations to confirm the level of resistance. the resistance broke down under heavy thrips Uuring the test period, the thrips populations were pressure. Several crosses were made utilizing these sampled in VITA-7, a susceptihle check, a t 38,43 and two cultivars. From one cross utilizing TVu 1509 and 48 days aftcv germination. The thrips populations per Ife Rrown. a local imprc~vedv ariety, a variety was peduncle were4.1 (S.D. k1.71, 11.3 (S.U.i4.1) and 9.5 developed (TVx 3236) that combines resistance to (S.U. i 3.8), respectively. These populations are con- thrips with the superior agronomic characters of lfe sidered fairly high; thrips samples taken on farms in Brown. TVx 3236 is only moderately resistant to Nigeria during the growing season varied from 2.1 thrips. Even so. the thrips resistance of this variety is (S.D. k0.3) to 6.2 (S.D.+1.9), indicating that the superior t c ~th at of all the others tested so far and has level of resistance in the newly identified cultivars been found extremely useful. (assuming that i t is confirmed in next year's tests) During 1982 eforts were made to identify thrips should be adequate. resistant lines superior to those identified earlier. Flower abscission and reduction in pod set were The germplasm collcction from TVu 4001 to TVu studied in the two thrips resistant cultivars, TVu 10.300 was screened. In ;r negative screening 1509 and TVx 3236, and in two susceptihle cultivars, conducted during planting in thc first season. about Ife Rrown and VITA-7. In measuring flower 10 cultivars appeared to be superior to the others. abscission and pod set, cultivars protected hy in- secticide were compared with unprotected cultivars. Mean number of thrips per plant The thrips populations per peduncle on unprotected VITA-7 varied from 3.6 (S.D. k 1.1) t o 6.1 (S.D. k 1.7). As shown inTable 15,t here wasless flower ahscission _rn and less of a reduction in pod set in the two resistant cultivars than in the check. A study of mechanisms of resistance to thrips was carried out in the greenhouse. The resistant variety TVx 3236 and the susceptible variety VITA-7 were artificially infested with 50 adult thrips per plant in cages. The thrips populations were measured 14 and 21 days after infestation. At 14 days the mean population of thrips larvae per plant in TVx 3236 was 3.9 (S.D.kl.8) and a t 21 days 12.0 (S.D.i2.3). The population in VITA-7 was 20.7 (S.D. k6.3) a t 14 days and 45.1 (S.D.i-8.6) a t 21 days. The differences between the populations on t h e two varieties were highly significant (P < 5'%,) a t both sampling dates. The low thrips populations on TVx 3236 indicate that antihiosis is the mechanism of resistance. In another experiment the natural population of thrips was observed from 37 to 60 days after planting on TVu 3236, VITA-7 and Ife Brown grown in the field in adjacent unprotected plots. The thrips populations were lower on TVx 3236 than on the other two cultivars as shown in Figure 8.-S.R. Singh and A.B. Salifu Insecticides Efficacy of fol iar insecticides. Nine diff'erent insecticide formulations were evaluated for flower thrips control in the field. Thrips populations and Days after planting cowpea yields are listed in Table 16. All t he insecticides tested were effective against thrips Figure 8. Comparison of thrips populations on resistant except Dipelx, which had no effect on thrips and susceptible cowpea cultivars, IITA, 1982. populations. ~ p d l i c a t i o nw i th t h e Elec t rodyn sprayer . Four formulations were significantly more effective than insecticide formulations applied on two crop rows Actellic?L and Dimethoate".-S.R. Singh with an Electrodyn sprayer were compared for their Cont ro l of hruchids i n s torage . This experiment effectiveness against flower thrips. As shown in was conducted primarily to develop technology for Table 17, the Cymhu~h"~aCndym hush + Dimethoate" small farmers who are storing only a few kilograms Table 16. Effectiveness of insecticides applied a s high volume foliar suravs against thrips, IITA, 1982 Mean number of thrips Per peduncle Per flower Dosage, 32 davs after 42 davs after 46 davs after 52 davs after Yield. Insecticide g/ha planting planting planting planting Decis + Dimethoateh.. . . . . . . . . . . . . . . 12.5 + 400 11.0 4.0 10.7 4.0 Sherpan (Cyperrnethrin) . . . . . . . . . . . . . Thiodan + Decis" . . . . . . . . . . . . . . . . . . . Cybolt"' (Flucythrinate). . . . . . . . . . . . . . Oftanol" . . . . . . . . . . . . . . . . . . . . . . . . . . . Zolone" (Phosalone). . . . . . . . . . . . . . . . . Tarnar~n,'.~. . . . . . . . . . . . . . . . . . . . . . . . Dipel" (Bacillus thuringiensis). . . . . . . . Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . LSD (.5 %.) . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 6.7 19.6 15.4 156.9 C.V., % . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49.0 99.3 79.3 96.5 14.5 Kote: Insecticides were applied 30 and 40days after planting. 66 Grain Legumes of' harvested cowpeas and have limited inputs for Table 17. Effectiveness of insecticides applied with control l ing cowpea bruchids, Callosohruchus an Electrodyne sprayer, IITA, 1982 nzaculatus. The treatments were as follows: mixing Mean number of thrips groundnut oil with cowpeas a t a rate of about 5 Per peduncle Per flower ml/kg, adding ash (about 40% by volume) to cowpeas, 35 davs after 46~ d~~ avs afte~ r~ Yield. mixing white sand (about 40% by volume) with them, Insecticide Ganting planting kg/ha and an untreated control. Each treatment consisted Cymhush"" . . . . . . . . . . . . . . . 9.0 11.0 958.9 of 3 kg of cowpeas in a cloth bag and was replicated Cymbush + Dimethoate,'LJ.. 4.5 14.0 932.1 four times. Each hag wasinfested with 35pairs of one- Dimethoaten . . . . . . . . . . . . . 12.2 25.7 637.4 day-old bruchids. and the percentage of seeds A~tellic'~.". . . . . . . . . . . . . . . 9.2 55.0 453.5 damaged was recorded four months after infestation. Control . . . . . . . . . . . . . . . . . . 15.0 57.7 414.7 Three samples, each containing 200 g of seed, were LSD (,5 %," ) . . . . . . . . . . . . . . . . 7.5 3 209.9 taken from each hag a t random, and the total C.V.,%.. . . . . . . . . . . . . . . . . 48.6 78.6 19.5 numhers of live and dead weevils per sample were compared. As shown in Table 18, the groundnut oil Note: Insecticides were applicd 30 and 40 days after planting. treatment was the only one found t o be effect,ive in controlling hruchids.-S.R. Singh and F.O. Beiuaji Table 18. Effectiveness of different treatments against cowpea bruchids, IITA, 1982 Cultural Methods of Control No- . o-f- we~ evils Treatment Damage, %, per 200 g of seed Cowpea variety TVx 3236 was interplanted with two cassava varieties, the high yielding TMS 30001 with Groundnut oil. . . . . . . . . . . . . . . 0.0 0.2 Ash . . . . . . . . . . . . . . . . . . . . . . . . 67.4 199.0 normal leaves and the low yielding TMS X with strap White sand . . . . . . . . . . . . . . . . . 98.0 167.6 leaves, to study the cowpea pest populations in Control . . . . . . . . . . . . . . . . . . . . 97.0 193.0 different crop combinations. Table 19 gives a summary of the results. The number of thrips in the LSD @'Yo). . . . . . . . . . . . . . . . . . 32.2 55.9 intercropped cowpeas was significantly lower thauin C.V.,% . . . . . . . . . . . . . . . . . . . . 46.0 38.2 the monocropped cowpeas during both cropping seasons. There was no real difference between the between border rows of Crotalaria, reported to be a populat,ions of the two intercropping comhinations. host of the pod borer, to test the use of this species as The Maruca populations were essentially the same in a trap crop for the pest. As shown in Table 20, the all treatments except during the second season, when percent yield in plots with Crotalaria borders and no the population on TVx 3236/TMS 30001 was lower as insecticide was higher t han in plots without a result of poor growth caused by excessive shading. Crotalaria. Maruca populations were also lower on Pod hug populations were much higher in the cowpea/Cratalaria plots with no chemical protection monocropped than in the mixed crop plots. than on the unprotected monocropped cowpeas These differences could have occurred for any of during the second cropping season. The reverse was several reasons. For example, the barrier provided by t rue in t he first season probably because of cassava may have hindered the movement of thrips. inadequate flowering by the monocropped cowpeas Or the cassava may have served as another food (Figure 9). Crotalaria may therefore provide some sourcc fur the bugs, thus diverting part of t he protection against t he borers, hut its effects on other population from the cowpeas. Nor should the pests have yet to he assessed. L.E.N. Jackai possihle effects of differences in micrometeorological factors, primarily the result of shading, he ignored. Virology An important observation made was tha t the major species of pod bugs in the second season was Screening for Resistance M i r ~ e r u sia culus. which would not have been the case had the cowpeas been planted alone. I t is clear Evaluation of cowpea breeding lines and potential from these results that interplanting cowpeas with breeding parents for resistance t o virus diseases cassava could be an important component in the continued in 1982. Most materials were screened for integrated control of cowpea pests. resistance to cowpea yellow mosaic virus (CYMV) In another experiment TVx 3236 was plant,ed and cowpea aphid borne mosaic virus (CAbMV), the Table 19. Insect counts on cowpeas interplanted with two varieties of cassava, IITA, 1982 No. of thrips No. of Maruca No. of pod per 20 flowers per 20 flowers bugs per 30 m First Srcond First Second First Second Cropping pattern season season season season season season TVx32361TMS 30001(interrow) . . . . 2:3.0(?8.9) 2.4 (k0.7) 5.9(21.8) 4.2(?1.0) 5 . 2 1 . 22.8 (k7.3) TVx3236/TMSX(interrow) . . . . 3 7.7(24.4) 5 .7(+1.4) 5.6(k1.5) 8.7(?2.0) 4.9(21.4) 40.5(?14.9) TVx 3236 (mnnocrooved). . . . . . . . . . . 73.1 ( t8.9) 276.1 (+85.9) 5.8++1.5) 8.1 ( + 1 .8) 13.2 ( t3.4) 66.8(+20.61 Grain Legumes 67 Table 20. Effect on yield of planting Crotalaria with cowpea improvement program with EMBRAPA were cowpeas, IITA, 1982 tested for resistance to the three most important Percent viruses in Africa (CYMV, CAbMV and CuMV). All yield of check eight lines tested were found to be highly resistant to First Second CYMV, a typical African virus of cowpeas. Treatment season season CAbMV was studied in great detail and compared Crotalarialcowneas. insecticide~ ~( check) . . - - with types of this virus reported from the United ~ , Crotalaria/cowpeas, no insecticide. . . . . . . 67.2 95.5 States and East Africa as well a s with a somewhat Cowpeas, insecticide. . . . . . . . . . . . . . . . . . . 9.4 70.1 similar soybean virus. A good antiserum was Cowpeas, no insecticide. . . . . . . . . . . . . . . . 1.0 68.0 obtained that allows rapid serological identification of the virus in N. henthamiana by the SDS agar gel two most important virus diseases of cowpeas in diffusion method. This technique did not, however. Africa. The only two, large, white, rough seeded give positive results when attempts were made to cowpea gern~plasrni ntroductions found to remain detect the virus in cowpeas. Nor were positive results symptomless after inoculation with CYMV (TVu obtained with the enzyme linked immunosorbent 7483 and TVu 5971) were shown to be immune to this assay (ELISA). virus in back-tests that involved grafting to a highly Seed lots of 31 elite cowpea breeding lines, susceptible cowpea variety. One cowpea germplasm multiplied for international testing, were evaluated accession, a selection from TVu 128, was identified for seed transmission incidence of CuMV. Only in that remained symptomless after inoculation with four introductions was some seed transmission six diferent cowpea viruses that are prevalent in observed, though a t low rates (0.4 to 39/,,).A s usual, Nigeria. Although this accession is highly suscep- 500 seeds of each introduction were germinated, and tible to anthracnose, i t appears to be a good virus plants were inspected through the first-trifoliate resistance donor for the breeding program. stage. Perhaps because introductions known for In addition to screening for resistance to CYMV their high seed transmission rates had previously and CAbMV, potential breeding parents were been omitted, neither any noticeable virus spread in screened for resistance t o cowpea mottle virus this year's multiplication plots nor subsequent seed (CMeV) and cucumber mosaic virus (CuMV), two transmission of CuMV was observed. This virus thus other viruses that are found in Nigeria. Also, some apparently does not occur in the wild flora and is advanced breeding lines from IITA's cooperative perpetuated through seed borne infections only, as is Mean number of larvoe per 20 flowers 28 7 Secmd Season -Crotalaria /cowpeas W ith insecticide Cr--*J With insecticide Jun.4 Jun.ll Jun.18 Jun.25 Nov. ll Oct.29 0ct.X) Nov.3 Nov. 6 Nw. I0 Nov. I3 Nov. I7 Nov 20 Sampling date Figure 9. Population levels of M. testulalis larvae under four treatments during two growing seasons, IITA, 1982. 68 Grain Legumes the case with soybean mosaic virus (SMV) in Improved grain types. Crosses were made soybeans. between the white, large seeded, bruchid resistant These 31 introductions were also evaluated for cultivar TVu 2027 and 1,ocal KamboinsG, SUVITA-2, resistance to CuMV. All introductions developed R-27 and Worthmore. Selections made for seed readily detectable symptoms, which in most cases character and other agronomic trai ts a re at the Fa were comparatively mild (2 to 3 on a 1 to 5 scale). stage. Plants whose seed color and size differed from Assessment of seed transmission, routinely per- that of TVx 3256 were also selected from crosses formed according to the method described above, involving TVx 3236. seems reliahle enough to be continued. Cowpea golden mosaic virus (CGMV). which is Plant type and maturity. Three trials were conducted a t different locations in Upper Volta to common a t TITA's substation a t Onne near Port Harcourt in the tropical rain forest zone of Nigeria, evaluate a range of photosensitive and nonphoto- sensitive materials that vary in plant type and was also observed in certain. apparently susceptible introductions during large scale germplasm re- maturity. The first trial consisted of 256 F6 lines, juvenatic~na t IITA during thc 198182 dry season. most of which were photosensitive. The trial was The reactions of germplasm introductions known to planted a t two locations, Kamboinsb (annual rainfall, 717 mm) and Farako-Ba (annual rainfall, 1,222 mm). he susceptible (TVu 22 and TVu 4557) with an isolate from TITA's fields were identical to the symptoms The lines were sown in single-row plots 5 m long in a induced in t,hese introduct,ions with isolates from the 16 x 16 simple lattice design with two replications. Maturity, yield, disease reaction, seed size and color Onne s u b s t a t i o n . H. W. Rossel and H. Huttinga were recorded. KVu 22-2, KVu 10-1 and TVx 6484- Cowpea Cucumovirus 6B2-K were the most promising lines. The second trial, which consisted of 225 nonphoto- For the first time, a good antiserum was obtained this sensitive lines, was planted a t Kamhoinsb and year for the cucumber mosaic-like virus, which Saouga (annual rainfall, 317 mm) in single-row plots commonly occurs i n cowpeas and lima beans in in a 15 x 15 simple lattice design with two replica- Nigeria (IITA, Annual Reports for 1978 and 1979). t i ons Disease reaction, maturity, yield, seed size and The virus was also tested with antisera t o some color were recorded. TVx 30-438-69, TVx 30-523-24 isolates of CuMV (obtained from the Office de la and TVx 30-470-30w ere the most promising lines. Recherche Scientifque e t Technique Outre-Mer), The third t r ial , carried ou t a t Kamboinsb, which is reported to occur on various crops in Ivory consisted of24 early maturing lines introduced from Coast. The isolates of CuMV for which the antisera lITA and collected locally from Upper Volta. The had been prepared were from cowpeas, wing heans yield. maturity and seed characters of the promising and peppers. With all three sera, a positive reaction lines are present,ed in Table 21. All the cultivars was obtained. The cucumovirus, originally obtained matured in less than 60 days. There were distinct fiom cowpeas a t IITA and maintained for further differences in seed characters, and those of the IITA characterization as well as for resistance screening, lines IT82E-71a ndIT H2E-60 were the most desirable. was propagated on N. glutinosa. The virus was The former is a rough, white seeded line, and the purified from N. glutinosa according to a procedure latter has white, smooth seed. described by Loehenstein e t a1 (1977). An antiserum was prepared hy injecting a rahbit with the purified Insect resistance. The aphid resistant cultivar preparations. The antiserum has a titer of 256 in TVu 36 was crossed with K N ~ al n d SUVITA-2, and microprecipitin tests and 128 in agar gel diffusion second hackcross material of these two varieties was tests, using purified virus a s a n antigen. The planted in the field for selection under nat,ural aphid antiserum proved to he suitable for detecting the infestation. Five to ten percent of the plants were cucumovirus in crude juice of infected N. glutinosa found to be susceptible and were uprooted. A total of as well as cowpeas, when using agar gel diffusion t e s t s . J.W.M. van Lent Table 21. Best cowpea lines in an early maturity trial, Kamboinse, Upper Volta, 1982 SAFGRAD Project in Upper Volta Days to Days to Seed color Genetic Improvement 50%, 50% Y~e ld , and l i n e flowering maturity kg/ha texture A major ohjective of t he cawpea breeding program of KVu 55 . . . . . . . . . . . . 39 57 1,496 BMS" the Semi-Arid Food Grains Research and 1)evelop- KVu 68 . . . . . . . . . . . . 38 5.5 1.466 RMS ment (SAFGRAD) Project is to develop improved K V u 69 . . . . . . . . . . . . 35 5'2 1,020 RS cowpea varieties that combine resistance to major 1T 82E-60. . . . . . . . . . . 37 68 1.316 WS diseases and pests with high yield potential for the IT82E-71. . . . . . . . . . . 36 55 1:046 WR dry savanna region. In 1982 emphasis was placed on LSD (5%,) . . . . . . . . . . 2.1 2.4 196 development of improvcd grain types and on in- C.V..O/, . . . . . . . . . . . . 2.7 2.1 22.1 corporation of insect resistance into promising "13 = hrown, M = mottled. S = smooth, W = whitc and cowpca lines. K = rough. Grain Legumes 69 24plants from thc backcross of KN-1 and 56 from that !?tested Plan's 1%) , - ~ ~ ~ (SUVITA-2 x T<" 36) x TVx 3236 were screened for resistance to aphid infestation. Disease reaction and plant and seed characters were also recorded. About 160 plants involving K N ~ la nd 57 plants involving SUVITA-2 were harvested. Thcse havc been planted in family rows to be screened for aphid resistance. Crosses were made between the bruchid resistant cultivar TVu 2027 and SUVTTA-2 and KN-1 to incorporate hruchid resistance. desirahle seed quality and agronomic characters into those varieties. From the cross TVu 2027 x SUVITA-2. individual plant selections were made and have been advanced to Fq.S ome of the lines have a high level of bruchid resistance. From the crossTVu 2027 x KN-1, Days after plontlng 42 Fzplants with resistance to bruchids wereselected Figure 10. Ratc of increase of' Striga in a cross between a and advanced to E':]. resistant and susreptihle cowpea variety, Upper Vulta. 1982. Striga resistance. The objectives of this work were to confirm resistance in SUVITA-2 and 58-57 The relationship between percent infestation and and initiate parallel studies on inheritance of Striga time of Striga emergence in the material discussed resistance. To confirm the Striga resistance of 58-57 ahove was also studied. The results showed that, and SUVITA-2, a field trial was conducted in a Strign emergence was generally earlier in the most checkerboard design in which the test varieties were susceptible parents and in their subsequent suscep- surrounded by the susceptible variety KN-1. The tible segregents (Figure 10). same material was also evaluated in pots in t,he Twenty-one F5 hulk populat ions involving screenhouse. Each variety was sown in 16 pots, 8 of SUVITA-2, along with two susceptible and two which were infected with Striga and the other eight resistant check lines, were evaluated for Striga left uninfested. The varieties 58-57 and SUVITA-2 resistance and other agronomic characters, includ- were found to be resistant both under field and ing yield and resistance to diseases. The fact that screenhouse conditions. Their level of resistance varieties 58-57 and SUVITA-2 had low infestation appears to be quite high. confirms their resistance. The susceptible check The inheritance of resistance to Striga was varieties, VITA-5 and TVx 3236, had infestation studied, us in^ F,, Fq, BC, and BC7 populationsfrom a cross betwein S U ~ I T A ~anZd -KN-1, along with parent The experiment was planted in a Table 23. Yield and Striga infestation in promising cowpea lines, Kamboinsi., Upper Volta, 1982 Striga infested plot. The plants infested with Striga were counted a t weeklv intervals until plant Yield, Plants infested maturity. The results obtained are presented in Table Line kg/ha with Striga, %, 22. The segrcgation ratio of susceptible to resistant TVx 30-141-1G. . . . . . . . . . . . . . . . 1,394 0.0 plants in the F2generation fitted the expectedratio of TVx 30~166-3G. . . . . . . . . . . . . . . 1,515 0.0 9:7 vcry closely, indicating a complementary gene TVx 30-312-3G. . . . . . . . . . . . . . . . 1.321 0.0 action. However, the presence of complementary 58-57.. . . . . . . . . . . . . . . . . . . . . . . 1,244 0.0 gene action was not supported by the segregating SUVITA-2. . . . . . . . . . . . . . . . . . . 1,041 2.3 VITA-5 . . . . . . . . . . . . . . . . . . . . . . 1,041 31.7 ratio obtained in backcross populations, which TVx 3236 . . . . . . . . . . . . . . . . . . . . 1,326 76.9 indicated monogenic inheritance. Further studies are needed to elucidate the exact nature of the LSD (5%). . . . . . . . . . . . . . . . . . . . 266 inheritance. c .V. ,%, . . . . . . . . . . . . . . . . . . . . . 30.3 Table 22. Segregation for Striga resistance in different populations of a cross between KN-1 and SUVITA-2, Kamboinsi., Upper Volta, 1982 Total no. No. infested Segregation ratio X2 P Population of plants with Striga Susceptible Resistant value value KN-I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 $0 1 0 0.49 .%.75I SUVITA-2 . . . . . . . . . . . . . . . . . . . 80 5 0 1 0.31 .75-.50 F,(KN-l x SUVITA-2). . . . . . . . . . . . . 57 52 1 0 0.44 .75-.50 F., (KN-I x F,) . . . . . . . . . . . . . . . . . . . . 211 128 9 7 1.67 25-.lo ~ t(KN, -1 x 'F,). . . . . . . . . . . . . . . . . . . 140 BC, (SUVITA-2 x F.) . . . . . . . . . . : . . . 206 70 Grain Legumes levels of 31.7 and 76.90/,, respectively (Tahle 23). Table 24. Tbrips populations in promising cowpea There were no significant yield differences between cultivars, Kamhoins6, Upper Volta, 1982 the resistant varieties and the check variety TVx No. of thrips No. of thrips 3236.-V.D. Aggarwal Cultivar per raceme" per floweP E n t o m o l o g y Untreated, farmer's field If'e Brown . . . . . . . . . . . . . . . . . . . . . . . . 34.8 Screening for thr ips resistance. A trial con- KN-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.4 sisting of TVu 1509, TVu 2870, TVx 3236 and two TVx2870 . . . . . . . . . . . . . . . . . . . . . . . . . 17.2 susceptible check varieties, KN-1 and Ife Brown, was TVx323f i . . . . . . . . . . . . . . . . . . . . . . . . . 21.5 planted during 1982 in a farmer's field and a t the TVu 1509. . . . . . . . . . . . . . . . . . . . . . . . . 11.1 research station a t Kamboinsi., Upper Volta. The Treated, farmer's field trial had a split-plot design. Its objective was to Ife Brown . . . . . . . . . . . . . . . . . . . . . . . . 4.4 compare the severity of the thrips attack under KN-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9 farmer's conditions with that a t the research station. TVx 2870. . . . . . . . . . . . . . . . . . . . . . . . . 3.5 For each variety treated and untreated plots were TVx3236 . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 compared. The treated plots were totally protected TVu1509 . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 by application of monocrotophos a t a rate of 400 g LSD (main plot). . . . . . . . . . . . . . . . . . . 7.9 a.i./ha during the raceme initiation stage to control LSD (subplot). . . . . . . . . . . . . . . . . . . . . 3.9 thrips and endosulfan a t 200 g a.i./ha 45 and 58 days IjSD (submain). . . . . . . . . . . . . . . . . . . . 10.0 after planting to control Maruca and pod sucking C.V. (main plot), '% . . . . . . . . . . . . . . . . 56.5 bugs. The untreated plots received only endosulfan C.V. (subplot),% , . . . . . . . . . . . . . . . . . . 44.4 to control Maruca and pod sucking hugs. Untreated, research station The results obtained in the farmer's field are given lf'e Brown . . . . . . . . . . . . . . . . . . . . . . . . 26.2 in Table 24. Significantly fewer thrips were found in KN-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.9 the treated than in the untreated plots. In the treated TVx 2870. . . . . . . . . . . . . . . . . . . . . . . . . 15.0 plots, there was no significant diflerence among TVx X236. . . . . . . . . . . . . . . . . . . . . . . . . 13.9 varieties in thrips population, neither in the racemes TVu 1509.. . . . . . . . . . . . . . . . . . . . . . . . 10.0 nor in the flowers. In the untreated plots, however, Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.8 the thrips population w as significantly smaller in the rA totnl of right samples were taken at three-day intervals. racemes on TVn 1509, followed by TVx 2870. There "A totnl of six samples were taken at threc~diryi ntervals. were also fewer thrips in the flowers of TVu 1509, but the difference between this population and those of Table 25. Effect of various dosages of monocrotophos TVx 2870 and TVx 3236 was not significant. Ife Brown on thrips and Maruca population and on and KN-I had maximum thrips populations both in yield, Kamboinse, Upper Volta, 1982 the racemes and flowers. Monocro- No. of No. of No. of The performance of these varieties a t the research tophos, thripsper thrips per Maruca Yield per station is also given in Tahle 24. There the trial was g a.i./ha raceme" Rowerh per flower plot, g planted in large plots and was not replicated. The trend in thrips population was much the same as in O . . . . . . 13.6 24.3 0.8 633.98 15 . . . . . . 8.5 15.3 1.1 556.72 the farmer's field, although the thrips population was 3 0 . . . . . . 7.1 12.9 1.3 627.48 somewhat lower a t the research station. In the 60 . . . . . . 7.8 12.8 0.9 582.78 untreated plots, TVu 1509 had the fewest thrips in the 120 . . . 6.6 12.6 1.1 689.85 raceme, followed by TVx 3236 and TVx 2870. In the 240. . . . . . 7.8 12.2 1.1 715.63 flowers TVx 2870 had the fewest, followed by KN-1. 480 . . . . . . 5.8 11.3 1.2 802.08 Both trials indicated that TVu 1509 has higher LSD (. 5%, ..,) -2. 7 4.3 - - resistance than the other varieties. C.V., ';b . . 27.8 25.2 44.3 29.88 Economic threshold of thrips. The objective of "A total of eight samples were taken at threr~dayin tervals. this study was to determine the relationship between bA total of seven samples were taketi at three~dayi ntervals. thrips population and cowpea grain yield. In the past two years, experiment results have shown a positive correlation between yield and monocrotophos control Maruca and pod sucking hugs. The results dosage. Butthese results havenot revealed any clear- obtained are reported in Tahle 25. There was no cut relationship between thrips population and yield. significant difference between the monocrotophos An experiment was conducted in 1982 with the dosages in their effect on the thrips populations, variety KN-1 to establish this relationship. Different neither in the raceme nor in the flowers. Significant concentrations of monocrotophos were sprayed once differences did exist, however, between the plots that at the raceme initiation stage to create varying received insecticide and those that did not. But these populations of thrips. Endosulfan was applied twice, differences were not reflected in the yield, which did once 45 days after planting a t a rate of 250 g a.i./ha not differ significantly among treatments. This was and again at 57 days at a rate of 400 g a.i./ha to probably due to the low population of thrips. Grain Legumes 71 Table 26. Maruca infestation in selected cowpea cultivars. Kamboinse. Upper Volta. 1982 Grain Percent yield No. of'l arvae Percentage of Percentage of Nu. of larvae yield reduction in Cultivar per 10 flowers" pods infestedh grains damagedb per 100 pods kg/ha untreated ylors TVu 1 . . . . . . . . . . . . . . . . . . . . . 21.7 7.2 0.7 2.2 990.97 -18.17 TVu946 . . . . . . . . . . . . . . . . . . . 17.9 24.3 4.0 4.7 629.92 - 7.57 TVu 946-13 . . . . . . . . . . . . . . . . 29.5 52.7 4.7 8.7 1,418.53 -10.98 TVr3236 . . . . . . . . . . . . . . . . . . 19.9 41.3 2.4 4.5 1,267.00 -23.31 VITA-5 . . . . . . . . . . . . . . . . . . . . 18.4 54.5 3.9 6.2 836.60 -41.71 SUVITA-2 . . . . . . . . . . . . . . . . . 22.5 37.0 2.8 1.5 1,775.05 - 7.79 1,ocal Kamhoinsk . . . . . . . . . . . 10.5 0.7 0.1 0.0 1,033.43 - 13.27 Mean.. . . . . . . . . . . . . . . . . . . . . 20.1 31.1 2.7 3.9 1.135.93 -17.54 "A tot.al ot'siu samples were takrn a t threc~nayi ntervals bBased on a sample of 600 pods. Screening for resistance t o pod borers Maruca. showed greater resistance than the other varieties.- Pod borers are another serious pest of cowpeas in the Y.S. Kathore semiarid environment. T r ~ arle sults in 1981 indicated that TVu 946, TVu 946-1E and Local Kamboinsi: had A g r o n o m y lower infestations than other varieties tested. In 1982 a trial consisting of those and other promising The objectives of the cowpea agronomy research varieties was conducted to confirm the resistance of program of IITA/SAFGRAU are to identify problems those lines and evaluate others for Maruca resis- in cowpea production and to develop new production tance. The trial was unreplicated but was carried out technology for achieving maximum economic yields in large plots (14 m x 10 m). in the African semiarid zone. Since this zone is so All the lines were evaluated with and without large, comprising 25 countries and stretching from treatment. In the treated plots, monocrotophos was West Africa through the Sahel and East Africa to applied during the raceme initiation stage a t the rate southern Africa, it has been impossible to conduct of 200 g a.i./ha to control flower thrips and during the research simultaneously in all parts of the zone. So, pod formation stage a t the rate of 400 g a.i./ha to the program has concentrated its main efforts in prevent damage caused by pod sucking burs. In West Africa. addition to monocrotopho~,t he treated-plots also Maize/cowpea relay cropping. An experiment received decamethrin a t the rate of 20 g a.i./ha to was conducted to determine the best time for control Maruca. In the untreated plots, only mono- planting photoperiod sensitive cowpea cultivars crotophos was applied to control flower thrips and with maize in a relay cropping system. With this pod sucking bugs. system the farmer should be able to make better use The numher of larvae in flowers and pods, the of the available moisture and inputs by obtaining a percentage of pods infested, the percentage of grains damaged and the yield are reported in Table Z6. TVu Number of MwM.0 loivoe per 10 fbverr 9 . 946.13 had the largest number of larvae in the flowers. Local Kamboind had the smallest number, followed by TVu 946 and VITA-5. The varieties TVu 1,T Vx 3236, SUVITA-hnd VlTA-5 were in the intermediate range. As shown in Figure 11, the distrihution of the Maruca population, based on the number of larvae in the flowers over a two-week period, was lowest in Local Kamboinsi: a t all sampling dates. The number of larvae in flowers was relatively highin the other varieties, as indicated by t,he peak in the figure. Flowering was, however, not synchronized for the test varieties. The number of larvae trapped in pods was lowest i n Local Kamboinsi., followed by SUVITA-2 and TVu 1. Yield was evaluated as a percent reduction from the yield of the treated plots. The yields of TVu 946, SUVITA-2 and TVu 946-1E were reduced less than those of the other varieties. Local Kamboinsb suffered a yield reduction of 13.27%, caused by Spodoptera littoralis, which infested 51% of the pods s~rnplmgd oter and damaged 16.81%, of the seeds. All measures Figure 11. Distribution of Maruca population in seven indicate that Local Kamhoinsb, TVu 1 and TVu 946 cowpea cultivars at different sampling dates, IITA, 1982.. 72 Grain Legumes Tahle 27. Effect of cowpea planting date on maize yielded less than the nonphotoperiod sensitive VITA- yield in a relay cropping system, 5. These results indicate that cowpeas can he relay Farako-B2, Upper Volta, 1982 cropped with maize as early as three to four weeks Cowpea planting date after maize planting without depressing maize yield. Cnwpea 7 23 5 15 In another experiment two maize cultivars of cultivar July July August August Mean different maturities -Pool-16 (90 days) and IRAT 102 k,g//za at 15% moisture (100 to 105 days)-were relay cropped with two VlTA-5. . . . . 4,789 5,623 5.081 5,544 5,259 photoperiod sensitive cowpea cultivars (Kaya Local, TAR 1696 . . . . . 4,370 5,273 5,521 5.668 5,208 which is relatively early, and IAR 1696, which is Kaya Local . . 5.126 5,815 5,668 5,138 5,437 relatively late) and one nonphotoperiod sensitive Mean . . . . . . . . 4.762 5,570 5,424 5,450 5,301 cultivar (VTTA-5) a t Farako-Ra, Upper Volta. The Comparison of means LSD (5%) C.V., ;6 maize cultivars were planted on 20 June and the Cowpea planting dates . . . . . . . . . . . . ns 18 i- 3.6 cowpea cultivars on twodates, 26 July and 14August. Cowpea cultivars . . . . . . . . . . . . . . . . . ns The experimental design was afactorial combination Date x cultivars . . . . . . . . . . . . . . . . . ns of two maize cultivars, three cowpea cultivars and two dates of planting in randomized complete blocks repeated four times. Tahle 28. Yield of cowpeas relay cropped with maize, Farako-Bi, Upper Volta, 1982 Neither the main nor the two- or three-way inter- actions affected maize yield significantly. Despite sig- Cowpea planting date nificant direrences in plant height (153 cm for Pool- Cowpea 7 23 5 15 16 and 215 cm for E A T 102) and in time of flowering cultivar July July August August Mcan (227 days for Pool-16 and 234 for lRAT 102), the two &/ha cultivars yielded about the same (4,306 kg/ha a t 15% VITA-5 . . . . . . . 767 555 645 668 658 moisture for Pool-16 and 4,202 kg/ha for IRAT 102). TAK 1696 . . . . . 638 698 185 349 468 Cowpea yield was significantly affected by cowpea Kaya Local . . . 822 838 849 785 424 cultivar and by date x cowpca cultivar and maize Mean . . . . . . . . 742 697 560 600 650 cultivar x cowpea cultivar interaction effects. The Comparison of means LSD (5%) C.V., "/, photoperiod sensitive cultivar Kaya Local out- Cowpea planting dates . . . . . . . . . . . ns 43.5 c 5 yielded the two other cultivars a t both datcs of Cowpca cultivars . . . . . . . . . . . . . . . . 199 planting and with both maize cultivars (Tahle 29). Date X cultivars . . . . . . . . . . . . . . . . ns However, the difference in yield hetween that cultivar and IAK 1696 a t the 14 August planting and full yield of maize and a yield of cowpeas on the same between VITA-5 and IAR 1696 when relay cropped piece of' land during the same growing season. with the maize cultivar IRAT 102 was not statisti- Two photoperiod sensitive local cowpea cultivars cally significant. The nonphotoperiod sensitive (Kaya 1,ocal and JAR 1696) and onc improved VITA-5 significantly outyielded the photoperiod photoperiod insensitive cowpea cultivar (VITA-5) sensitive IAR 1696 only when planted on 26 July and were planted a t four dates in solid rows alternated when relay cropped with Pool-16. with maize rows. The spacing in cowpeas was 0.75 m The reaction of cowpeas to late planting and to between rows and 0.20 m between plants within rows. relay cropping with the tall and medium maturing The crop was sprayed four times a t ten-day intervals, maize cultivar ZKAT 10" varied with the cultivar. beginning a t floral bud initiation, to control flower Late planting did not significantly depress the yield thrips and pod sucking bugs. The maize cultivar Pool- of VITA-5 and Kaya Local hut increased the yield of 16 was planted on 19 June a t the optimum density IAR 1696. IRAT 102 significantly depressed the yield (53,333 plantslha) and a t spacing of 0.75 m x 0.25 m. of Kaya Local, increased the yield of IAR 1696, and The crop was fertilized a t planting with 35:25:13 and had no effect on VITA-5. four weeks after planting with 45 kg N/ha a s urea. The results are presented in Tables 27 and 28. Maize yield was slightly depressed when cowpeas Table 29. Yield of cowpeas intercropped with maize were planted 28 days after maize, hut later planting cultivars of different maturities, had no cffect on maize yield. The yield of cowpeas Farako-Bi, Upper Volta, 1982 relay cropped with maize was significantly affected only by the cultivar. Thc early photoperiod sensitive Cowpea Cowpea planting date Maize cultivar cultivar Kaya 1,ocal yielded significantly more than cultivar 26 July 14 August Pool~l6 IRAT 102 the late cultivar IAR 1696. The nonphotoperiod sensitive cultivar VITA-5 was intermediate in yield hetween the two. Early plantings of this variety Kaya 1,ocal. . . 767 IM 1696 . . . . 200 performed bett,er this yedr than in 1981 because of poorer growth in t h e associated maize. The Comparison of means LSD (5"/,) C.V.. %, photoperiod sensitive IAR 1696 flowered very late, Date x cowpea cultivars . . . . . . . 195.1 38.5 i 4 suffered more from pod sucking hug damage and Maize x cnwpea cultivars . . . . . . 195.1 lqds e SUM u2!sap [equaUI!~adxd aq& 'Rl1oA ~ a d d n ' lqZno~p)s zolaej [-eluauruol!Aua Lj!luap! 07 pue .?su!oquen l e (suo!$aJauoa jo wxoj aq l ur l u a s a ~ d olep Yu!quqd urnruqdo ayl au!urlalap 07 palanpuon s! ya!q~,jo3 ~ 0'UsOJ ! aaxj pue apuqo-ey u! ya!~s! l eq l ST!M ~uam!Jadxa u v '7uama;ft?ut?ur eadMo3 I O ~ X Ou e) ,.xnau!S!~~aj[ a s i iu o euuehss uepns aql ,9691 H\?I aA!l$suas po~zadoloqda q l pap1ayLlno u! (ado[s JaMol q $ ! J~ay lo aql pue a d o ~usn lpam y l ! ~ Ll1ueay!u81s ';-~J,IA xeA!lIna ah!l!suas po!.radoloyd auo) sa)!s OM^ IF salop Sugueld aaayl l e paqs!Iqnlsa -uou aqL .ny/s?ue[d 999'99 ?e [aha[ unurqdo SBM (ai\!?!suas po!~adoloqduou s e ' ~L . N '~m ay) JO ue paqaeaJ pug Ll!suap Su!sea~au! o l L[a~!q!sod auo Lluo) sJenqln3 x!s ylrM )uatu!~adxa Je[!ur!s v pu0dsa.I o l pual p!p p1arL g2noql 'laqloue auo .(uw pue 1v 'ad jo sap?xo!nhas moxj L[lue3yruS!s Jag!p lou p!p sluam7ea.q 2u!ddo~a pue a)!u!Iocy u! q"!n! lnql uo!$aeg L ~ 1 3e q q ! ~ Le1a.I snotJ-e.4 aq? u! sp[a!h '(OF a[qe,~) suo!le[ ~os!xou e) 110s a!y~~ez.cuar,e~o l-Le~a-Kpuuas uo ' - e l ~ o ~ -ndod l u e ~ d[I n qe seadMoa paddom L q a ~pa p[a!L Jaddn ' ~ 8 - o y e ~)eed e u u n ~ eesa u ! n ~u -raqllou aqlu! -In0 L~lueay!uS!s luamleaxl eadmoa punls-a~nd sal-ep Zu!lueld Jnoj 7e pJ$sal azam '(L-VJ,II\ L[~am~o,j) aq& 's%uaurleaqp ue sJeh!qna e a d ~ o aq l Lq palaage I - N '~J G A ! ~ ~ V J aAg!suas po!~ado)oqduou pa~oxdru! L1$ueay!uY!s SUM p1a1L eadmoa 'JaAaMoH .(6'&+ u-e pun sJr:A!$[na eadMo3 l a a o ~ah !l!suas po!zadoloqd 'yoL.lt: = ' ~ a3Jnl)s!o ur [ranas 'salr!p Zu!?ueld sno!JnA 1-e eq/Zy ~ 1 9p a' 2~e . w ~ ~ pa spla!L sadMos ~!uI!~ q3!qM 'p[a!L aarnru palsage L[lueoy!u3!s saqrsuap dew qnql (slsad laasu! uey? Jaylo sq!semd zo a seasy l u e ~ eda dM03 aql ~ o suxe ~!l[nae admo3 ayl aayqaN .slo[dqns aql aJaM sa!l!suap lus[d aql pu-e CSI . . . . . . . . . . . . . . . 'slo[d u!nm aqlazaM sJeA!l[na eadmoa aq&. sau!lznoj 53 1Rp $J!p 'sJBA!)1113 ceI . . . . . . . . . . . . . alr" ~ ' 3 ("LC)a s? sueam ,+ou os!.mdmog aJnd v ' ( sq / s lu~Isds s'ss1 PUB I11'111 '999'99 'ZZZ'ZZ) 'suo!le1ndod l u e ~ dJn oj 1e qaea qsn2nv g uo az'em u! L9E'I PL6 OXI'I 219'1 ZOL'I " " " " m%?am paluqd aJaM '9691 ~1 pue ~ - ~ J , I' sA~ e ~ q [una3dm on P6L'I BIZ'[ LliZ'I 6C6'1 IZL'Z "(~"""d"!) OM& '(UI L9L.O X W 06.0 30 3~!seds pue aXB33aq zad 1-NX 216 ZIS 989 SZE'I PZI'I s l u n ~ dy yy'gg jo uoqqndod e 3-e aunp uo palue[d ' ' ' ' ' 9691 83'1 06Z'I 9EI'L EZI'I 62S'I PLC'I SUM g[-[ood 'eaxe PUB[ ?!un lad uo!qe1ndod lueld ' ' ' ' ' ' IBJU? nssno~9ol %u!sea~au! Lq JOJ palnsuaduroa aq ue3 az!em g l ! ~ SZP'I 666 690'1 ZSR'I 1 6 ~ ~ 1az notl l ~ a o ? 2u!ddoxa L4[31 u! ql~0.18e a d ~ o apa anpal JaqlaqM ?su!oqmrq au!mJalap 07 ?no pa!~~-eas eM luaur!~adxa u v ZLS'I ZLZ'I 608.1 0~9.1 LCC'I JPN 1~30'1 'sluaurleaal asaql u! az!nru paanpax ,O asu!oqurna C' [ . . . . . . . . aql O l palnq!Jluoa aARq OSlL. hem sYu!a-eds MoJ ap!M PRZ'I 6PO'I 991'1 919'1 - LCE 7x3 SMOJ u!ql!~ slue[d uaaMlaq uo!pladuoa 2uoqs IPC'I 9% LbE'I 8Z9'1 PSP'I ' " 113307 ~ L R W -euuenes eau!n:) ciql u! po!Jad MO[[~SJU OIe aalje 91E'I 899 I?6 OPC'I 9OE'Z ' " " . 1 ~ 2 0 7 d~u3rlhas[ e u u q e l o ~t: jo dol ayl 7-e pa lue~ds! az!em D Y I ~ Y aLnoZ!qsng uaqM s ~ n a a o3 cql Laua!ayap N L ~ e ~ o d m a ql l jo u n a 1 ~l sn8nv ~snZnv L[np Llnp JuA!llnD asneaaq (Z T 'y0/061 s - e'~~ 'a3ql P UB U I 0~1 [ se~lqZ!aq SI C 9Z 8 luuld unam aql) xood A J ~ A S BM yl~o.18a h!leqa8aa alBo 9urmnrJ azr-elu q-eql palou aq p[noqs 11 ' ( z . 5 ~z .61 = ' ~ ' 3 ) aq/Sy LZL jo a9ezane ue paanpozd qaqM 'seadMo3 padd0.u L e l a ~,+ o p p . 4 ayl palaage L[lueay!uS!s suo!lmzalu! z!aql zou s7aa.p u!r:u aql Jaql!aN ' ( 8 ' ~ - s u . . . . . . q n 3 ~ a d ~ xo n'do d ? u B [ ~ -t % ~ ' c c= '11.3) S U ! ~ R ~ S U UqeT e-qO/S~y[ O LP'Z 07 pue 9.EItii.cP 6.9t'Z . suo!le[ndnd ?ue[d Qu!aeds W-5~1.1 e eq/2y 9 ~ sol' 2~u! 3eds ~ 0 . xW - ~ L . O s.O+ 9.PI ZFL . . . . . . . . . . S J B A ! ~ T ~ Jw ad~o:) lu sq/Zy 186's WOJJ" 7,;os unq1 azom bq pp!L az!em passaxtap s2u!suds M ~ aJp! M .g1-1ood JO p[a!L aq? O , , "A.3 ( ' m US'I sueam ja uos!.cudmo:) FEY u . . . . . . . . . . . . . . . . . . . .u naw pa?aaga L~lueay:uS!s du!aeds MOJ ~Z!UUI aq7 L ~ U O 66f. 6°F 066 . . . . . . . . . . . . . . . . . . . EPX 969 9911'99 '-eq/sluo[d 999'99 s e lu~au rleaq q:ma JOJ uoqe~ndod prlels alnd qua[d nadmo:, aq& 'palun~dS UM MOJ eadmoa auo L[uo PLS . . . . . . . . . . . . . . . . . . . IIP XPZ $>SS,,C~9I alaqM 'Su!~eds M O J ru-sL.0 ylrM Xz~eUla ql U! qdaaxa P[9 . . . . . . . . . . . . . . . . . . . XCP IOE LII'III 'SM0.I aZ!VUI U33Mlaq palunld 9JaM s-V&IA 30 SMOJ . . . . . . . . . . . . . . . . . . . ZLP ICE 999'99 OM& '(eq/slue[d 999'99 pu-e PPP'PP) suo!le[ndod lue[d ZOP . . . . . . . . . . . . . . . . . . . OIF 81Z ZZZ'ZZ OM1 pUR (UI 0S.L pUR sZ1.1 'SL'O) sYu!at?ds MOJ aaJql le Uyl.'Y 2u!ddo~n L u j a ~ aunp L Z uo palueld seM g[-~ood~ e~!71na3z !em aqL u w a ~ 9 691 XVI 9-V,LTA a.rwJaq zad 'uo!ln[ndod lue[d pue JRA!$[TJ u a d ~ o ~ slue~dju'O N S u I ~ n d Ms 0 1 aZ!L?W U! SlUaUIlSll~pt!q Snolql seadM03 ,#o p[a!L aql BurseaJDu! aI!yM [aAaI L~oyarqs!les e 1~ 111a1L 3qem Yu!u!elu!eu Lq paseaxau! aq una ualsLs 2u!dd0.13 LepJ ~ ~ ~ M o ~ / -~F jo~ LI lR!~urpI n po~[dq o l aql ,J! au!m."alap ol palnnpuoa snM luaur!zadxa u v 74 Grain Legumes plot, with planting dates as main plots and cultivars Table 33. Effect of planting date, seedbed preparation as subplots. Each plot received 50 kg P20s/ha as and position in the toposequenee on superphosphate. cowoea vield. KamboinsB. U o ~ eVr olta. 1982 In the northern Guinea savanna, KN-I yielded Planting date better than any other cultivar a t the 8 July planting 19 July 5 August date (Table 31). When planted late it yielded about Seedbed preparation &/ha the same as most local cultivars, but significantly Flat . . . . . . . . . . . . . . . . . . . . . . . . . 668b 120 d less than Kamboinsb Local Noir a t the 5 August Tied ridges. . . . . . . . . . . . . . . . . . . 910 a 575 c planting date. During the growing season, the foliar disease rust infected all the cultivars except KN-I and was most damaging to cowpeas planted after 26 July. Some Position in the toposequence cultivars (Ouahigouya Local, Kaya Local and Upper slope . . . . . . . . . . . . . . . . . . 555 c 257 f Kamhoinsir LocalRouge) were highly sensitive to the Medium to upper slope. . . . . . . . . 923 a 324 ef Medium slope . . . . . . . . . . . . . . . . 989 a 360 de disease; their leaf area and yield were drastically Lower to medium slope . . . . . . . . 703 b 328 ef reduced (Table 31). Other cultivars (Kamhoinsh Lower slope . . . . . . . . . . . . . . . . . . 774 b 467 cd Local and Logfrousso Local) proved to be more tolerant. Since insecticide was applied only four LSD (5%) . . . . . . . . . . . . . . . . . . . . . . 127 times a t 10-day intervals (beginning a t floral bud C.V ., V/,. . . . . . . . . . . . . . . . . . . . . . . . 23k initiation by KN-1), IAR 1696, which flowered very Note: Means followed by the same lctter are not slatistically late, was not well protected and suffered severe difl'erent at the 5'Yu probability level. damage from pod sucking bugs. In the Sudan savanna crop yields were markedly yielded better than the other cultivars (Table 32). Since it was free of Striga, its yield reduction reflects ~ ~ only drought damage. Even though this cultivar was cultivar depended on its resistance, tolerance or more drought resistant than t,he others, its yield was susceptibility to Striga and drought. Gorom Local, significantly reduced by as much as 50% a t the latest which was grown only a t the medium-slopc site, planting date. Ouahigouya Local yielded about as much as KN-1 a t both sites when planted on 19 July Table 32. Effect of planting date on cowpea yield, (Table 32). It outyielded KN-1 a t both locations when Kamboinse. Uvoer Volta. 1982 planted a t the later dates except for 31 July a t the Planting date medium-slope site, where the difference in their Cultivar I9 July 31 July 10 August Mean yields was insignificant. Quahigouya Local flowered 46 days after planting Medium-slope soils &/ha and KN-1 a t 42 days. Striga emerged in the former 46 Ouahigouya 1,ocal . . . 612 341 297 416 to 49 days after planting and in the latter a t 53 to 59 Kaya Local . . . . . . . . . . 15 66 149 77 Kamhoinsi. Local Noir 55 181 275 170 days a t both sites. In the poor yielding cultivars Gorom Local (Kaya Local, Kamboinsb Local Noir and IAR 1696) (SUVITA-2). . . . . . . . 1,003 681 582 755 planted a t the two early dates, Striga emerged long IAR 1696. . . . . . . . . . . . . 5 2 0 2 before flowering and therefore may have been KN-l (improved). . . . . 595 247 176 339 responsible for their poor performance. IAK 1696 Mean . . . . . . . . . . . . . . . 381 253 246 293 suffered both from Striga and drought. Comparison of means LSD (5%) C.V., npoq su!ezs [ u u o ! $ ~ ~ , Joj aauadzaura zu~[paas. ~ 8 6 1' ?sea3 L Z O A's~a uq Su!rn?em 629 R6P 692 OP9 9ZP ' ' (%S) CIS? mn!pam EZ (8) pun mu![ 4u!paalq ueaqSos Bu!~nlem ale[ 9~ SPE'I OPS'I ~ Z Z ' I Z B P ' ~ ~ P Z ' Z' ' ' ueam l u ! ~ ~ , (Q) 305 a4e~ol?su a!quejo sq?uom iqz:a .ca?jnp azzarna szuq -paas $0 aze~uaaxadlo 3 uoyq!.z?s!p b a u a n b a ~ ~ 3.1n4!~ 9OF'I 4PO'T [ZS'T EX6 998 OZI'Z ' ~ L E Lm 3,L - C6Z 111'1 ?OG SF9 - . . . . .za!ssog pabiaua sbu!lpws $0 aboluasliy y3aq3 OP9'1 66E'I L6L'I 9ZP'L 111'1 OLP'Z ' '399-EEY x3,L 099'L C98'1 E6L'T PV6 T9t"l LXZ'Z ' ' '3E-ZCZ X3,L t18'1 C19'1 19G'I FSS'L ITB'T RE9'Z ' '3LF-EFS X3A OOL'I ESS'L L9S'L 9L6 9P8'1 199'2, '3OOL-9CS x9,L 66L'I L9['i PZ8'1 PPP'I XOZ'Z ZSE'Z ' . '32-ZPS x9,L 928'1 IPP'L 261'2 LII'1 SVZ'Z LEZ'Z '3SE-L6Z X3,L IPI'Z 991'1. IXR'T 028'1 416'1 SZ6'Z'3ZfiI-L6ZXDJ, ~'i l .% .'%,LL( ~ L E~L 6 3ya~arla) p oo%a yl Joj pua %SI sem (ralssos) ysaq:, mod aql JOJ aaua4aama SuI[paas syaaqa iseo3 L r o ~ l 'Za6I 'sax![ 2 66 ((8 pue dl!Aaaunl paas .roj palaalas aq? ~ o91j 0 1 I pue syaaqo amq.eq.m r.-z ar-l l JO"T 1. se m JaqUrnu sauq au!paa.rq ueaqdos fig (Q) '03 (b?!p!urny aA!?qa.' U/ ,g l aql 'g .roa 3 0%1 moq padua~sy aaqa l e so~aq l jo lueI;l rad pun 3 0?e~ syaa~M x !s spaas 3u!.zols hq) Bu~aXep alexalaaae salnpoujo Jaqmnu aq? 'v .'od '2861 'saug Zu!ln?em ale1 gt. JWe B!J~~!NU ! SUO;?BDO[ snn!JeA 111 pa3.raua s9u<[paas "03 iseog Lro~ L1IT OM? pue amqeqmrz u1 uo!?eao[ auo 1a.m jo a%eluaazad J ~ Juo !?nq!~?s!p L3uanba.z~- p[ asna!$~ (8)ut p u s~au ![ 3u!paalq ueaqLos %u!rn?em wnlparn oz JOJ ?sen3S aoh[ U! suO!?B.10[ OM? JaAu (v)u ! pa4exohe '$uqd .zad . salnpou .fo Jaqrnnu so3 uo!lnqp?s!p Lauanba~.jZ I a ~ n z ! ~ -Y -g 8- juold lad ralnpw lo laqwnu uoao I , , 8 : 8 Grain Legumes 79 Table 41. Yield and nodulation of elite, promiscuously Table 42. Yield and nodulation of ~romisin- em, edium nodulatine soybean varieties. Zaria and maturity breeding lines in a preliminary Mokwa, ~Tgeria1,9 82 yield trial a t various sites in Nigeria. 1982 Zaria Mokwa (NGPC) Mokwa With Without With Without Line Zaria (ABU) Ilorin Ihadan Variety N N N N M-90 (IAR) TGx 326-034D Yield. ke- lha . . . . . . . . . 1.927 1.624 1.522 338 Yield, kg/ha.. . . Nodulationa. . . . . . . . . 2.3 2.8 3.9 3.1 Nodulations. . . . TGx 72501D TGx 330-054D Yield, kg/ha.. . . . . . . . Yield, kg/ha.. . . Nodulation. . . . . . . . . . Nodulation . . . TGx 724-01D TGx 457-060C Yield, kg/ha . . . . . . . . . Yield, kg/ha.. . . Nodulation. . . . . . . . . . Nodulation . . . . TGx 789-02D TGx 604-028C Yield, ke-. lha . . . . . . . . . Yield, kg/ha. . . . Nodulation. . . . . . . . . . Nodulation . . . . TGx 713-06D DSM 490 Yield, kg/ha . . . . . . . . . Yield, kglha. ... Nodulation. . . . . . . . . . Nodulation . . . . TGx 70906D M-79 (IARh) Yield, kg/ha . . . . . . . . . Yield, kglha.. . . Nodulation. . . . . . . . . . Nodulation . . . . TGx 70903D Bossier (nonpro- Yield. kalha.. . . . . . . . miscuous check) Nodulazbn Yield, kg/ha.. . . TGx 726-01D Nodulation . . . . Yield, kg/ha.. . . . . Trial means Nodulation. . . . . . . . . . Yield, kg/ha . . . . Jupiter (nonpro- Nodulation . . . . miscuous check) LSD (5%) Yield, kg/ha . . . . . . . . . Yield., k-e, lha.. . . Nodulation. . . . . . . . . . Nodulation . . . . 0.2 0.6 Trial mean Yield, kg/ha.. . . . . . . . *Nodulation scores: 1 = poor nodulation, 2 = fair nodulation, Nodulation . . . . . . . . . . 3 = good nodulation and 4 = excellent nodulation. hlnstitute of Agricultural Research, Abmadu Bello University, LSD (5%) Nigeria. Yield, kg/ha . . . . . . . . . Nodulation. . . . . . . . . . "Ndulation scores: 1 = poor nodulation, 2 = fair nodulation, 3 = good nodulation and 4 = excellent nndulation. agronomic characteristics and ability to nodulate with indigenous rhizobia of F6 generation breeding Table 43. Yield and nodulation of promising, late lines derived from complex crosses involving parents maturing breeding lines in a preliminary that have the promiscuous nodulation character, yield trial, Ilorin, Nigeria, 1982 superior seed storability and good agronomic charac- Yield, Nodu- teristics. As mentioned above, nodulation with in- Line kg/ha lationa digenous rhizobia at Zaria was very poor, at Mokwa TGx 742-3D . . . . . . . . . . . . . . . . . . . . . . 1,723 2.3 (ABU) fair, and relatively good a t Ilorin and Ibadan. TGx 742.50 . . . . . . . . . . . . . . . . . . . . . . 1.609 3.3 Yields were low at Ibadan because of drought stress. TGx 293-031). . . . . . . . . . . . . . . . . . . . . . 1,420 3.4 The performance of several promising lines is given Malayan (local check). . . . . . . . . . . . . 1,325 3.1 in Table 42. The storability of most breeding lines Jupiter (nonpromiscuous check) . . . 1,029 2.5 was superior to that of the check variety, Bossier Trial mean. . . . . . . . . . . . . . . . . . . . . . . 1,106 2.6 (Figure 14). Trial LSD (5%) . . . . . . . . . . . . . . . . . . . 591 0.9 Preliminary t r ia l of la te matur ing lines. As rNodulation scores: 1 = no nodulation, 2 = fair nodulation, with the medium maturity preliminary trial, the 3 = good nodulation and 4 = excellent nodulation. objective of this trial was to assess the agronomic characteristics and ability to nodulate with in- Ear ly generation nurseries. Selections from digenous rhizobia of F6 generation breeding lines. early generation nurseries and F2 populations were The trial was sown at Ilorin and Ibadan, but because advanced one generation at Ibadan during the of severe drought stress a t Ibadan, that trial was 1981-82 dry season and grown at Zaria and at Mokwa discarded. Several lines that performed well a t Ilorin during the 1982 main season (Table 44). All lines and are listed in Table 43. populations represented a second cycle of crossing 80 Grain Legumes Table 44. Early generation nurseries Meon numberof bvgo pw 2m of row Nursery Entry Selection 198142 dry season, Ibadan F2 promi~cuoun~od ulation, 7 populations Advanced seed longevity and pod in hulk bug resistance F3 promiscuous nodulation, 402 lines 987 seed quality and early maturity 1982 rainy season, Mokwa and Zaria F2 promi~cuousn odulation, 98 populations 368 seed longevity and pod bug resistance F3 promiscuou~n odulation, 7 lines 296 seed longevity and pod bug resistance F, promiscuous nodulation, 987 lines 1,369 seed longevity and early maturity ------- sept Osl 1982-83 dry season, Ibadan Sompllng dote F2 promiscuous nodulation, 164 populations seed longevity, stem Figure 15. Population of pod sucking bugs on two cowpea strength and shattering varieties, Mokwa, Nigeria, 1982. resistance F3 promi~cuousn odulation, 368 lines Table 46. Soybean yield in protected and unprotected seed longevity and pod plots a t two locations in Nigeria, 1982 bug resistance Percent F4 promiscuous nodulation, 296 lines Variety Protected Unprotected loss seed longevity and pod Mokwa bug resistance Fj promiscuous nodulation, 1,369 lines TGm 344 (iS.E.) . . 2,620.5 1.585.1 39.5 seed quality and early maturity TGm 579" IITA TGm 17-26ER . . . . . 1,657.6 1,222.4 26.3 between superior breeding lines involving promis- "Unreplicated plats. cuous nodulation andseed longevity. Thenew parent material also included parents with pod bug re- Mokwa and 56% a t Ibadan (Table 45). The bug sistance, stem strength, shattering resistance and populations on the two varieties planted a t Mokwa early matur i ty . E .A . Kueneman and W.R. Root were identical (Figure 15); their means for the entire sampling period were around eight bugs per 2-m row, which is the economic threshold (4 to 8 bugs per 2 m) reported from other countries. This population was Two soybean varieties (TGm 344 and TGm 579) were large enough to cause substantial yield loss (Table planted a t Mokwa and one (TGm 17-2GE) a t lITA for 46). TGm 579 may have suffereda greater loss because a survey of the major insect pests associated with the of its earlier maturity, which could have caused it to crop. Only pod sucking hugs were observed in con- attract a greater number of pod bugs much earlier siderable numbers a t both locations. than did TGm 344. At IITA, where bug populations The predominant species was Nezara uiridula, were lower, yield loss was still close to 30%. which represented up t o 75%, of the population a t The results clearly indicate the importance of pod sucking pests a t certain locations in Nigeria. There is Table 45. Species composition of pod bugs a t two an immediate need for concerted research efforts to locations in Nigeria. 1982 obtain the da t a needed t o formulate control Mokwa measures.-L.E.N. Jackai IlT A TCM 344 TGM 579 TGM 17-2CE Nezara . . . . . . . . . . . 74.8 70.1 55.7 Virology Piezodorus . . . . . . . 11.1 11.1 1.1 Acrosternum. . . . . . 6.2 1.8 6.3 Soybean viruses can cause yield losses and, when Aspauia . . . . . . . . . . 3.8 13.4 29.4 seed borne, prevent movement of germplasm among Othersa . . . . . . . . . . 4.0 3.6 1 5 countries. Several viruses identified in Nigeria are "Others include Anoplncnemis, Clauigralla tommtosicollis, being studied to ensure that virus diseases do not C. shadehi and Iliptnrtus. reach epidemic levels. Grain Legumes 81 Soybean Mosaic Virus tic mosaic was seen a t low incidence in soybeans at TITA both during the rain-fed growing season and in Soybean mosaic virus (SMV), the most common the dry season. This new potyvirus appears to be soybean virus disease, was of little or no importance different from SMV and the African yam-bean-like in this year's crop a t IITA and in off-site experiments virus in that it causes a characteristic blister mosaic. a t various places in Nigeria. Extensive rogueing in All ~nfectionfso und in the dry season multiplications the preceding breeding and multiplication cycle has appeared to be secondary (natural) infections from apparently paid off. High seed transmission rates of outside the crop and not seedborne infections. The this virus in many genotypes is beyond doubt the virus therefore seems to be indigenous to this region most important factor in reoccurrence and sub- and does not appear to have come in through sequent epidemic spread of this virus in any new seedborne infection. crop. In locally grown soybeans (Malayan), no SMV was found during surveys this year. Absence of seed transmission in these types must be considered A New Virus Disease responsible for the absence of SMV since Malayan is not resistant to the disease. In the main growing area around Yandev in south A set of 20, well-performing, SMV resistant lines central Nigeria, both in experimental plots as well as obtained from the International Soybean Program in farmers' fields, yet another severe viruslike (INTSOY) a t the University of Illinois a t Urbana- disease was observed, though a t low incidence. Champaign, United States, was tested with the two Symptoms are a blotchy, whitish yellow vein pattern, SMV isolates that we are maintaining for further mosaic and distortion. No disease of this kind has studies and for resistance screening. Fifteen of these been observed previously. Although a virus was proved to he highly resistant to our SMV isolates, isolated from field samples by means of inoculation to and therest developed only mild symptoms. Marginal N. benthamiana (but not to soybeans), transmission differences were observed between the reactions to from N. benthamiana hack to soybeans proved the two isolates. successful, and symptoms similar to those seen in the field were observed. In spite of the sap transmissibility and severe Soybean Dwarf Disease symptom expression in soybeans with one of the The severe and potentially important dwarfing three isolates maintained, no virus particles of a disease, which earlier was tentatively identified as definite type could be associated with the disease. soybean dwarf virus (SDV) and was reported from Even in N. benthamiana, in which the virus Japan, appears to be caused by an entirely different apparently reaches a high concentration, no virus- and probably hitherto undescribed virus. It was like particles could be identified with certainty. ~- found to be efficiently transmitted by white-flies H. W. Rossel (Bemisia tabaci). Still, as found earlier, clearly positive reactions were obtained in agar gel diffusion tests, using an SDV antiserum, with most field Soybean (2) Virus Isolate infected plants, but not with those inoculated in the A new disease in soybeans (code named soybean (2) greenhouse. No explanation can be given for this virus) was recognized that causes curling of leaves result since precipitation lines are typical of virus- and mild mosaic. This disease can be differentiated specific reactions and no such lines have ever been from the most common virus disease of soybeans, obtained with healthy plants. soybean mosaic, by the fact that soybean (2) virus Interestingly enough, the Malayan germplasm causes severe symptoms in Nicotiana benthamiana introduction TGm 107 was found to be highly (Rossel, unpublished data). Electron microscopic susceptible to this disease. But although the virus examination of leaf dip preparations revealed was found to occur in experimental fields of Malayan, filamentous particles typical ofthose in the potyvirus it was not seen in locally grown Malayanin the major group. growing area around Yandev, Nigeria. On testing The virus was purified according to the method Malayan collected from farmer's fields in that region, described by Lima e t a1 (1979), with a slight we found that it possessed a considerably higher modification, followed by two cesium chloride level of resistance to this disease than TGm 107, centrifugations as described by Taiwo et a1 (1982). which explains the absence of this disease from An antiserum was prepared by injecting rabbits farmers' Malayan in the major soybean growing area with the purified virus preparations. The antiserum of Nigeria. obtained has a titer of 11256 in microprecipitin tests. In immunodiffusion tests (SDS) the virus proved to be Blister Mosaic remotely serologically related to CAbMV as it occurs in cowpeas in Nigeria. Further experiments are under- In addition to SMV and a potyvirus similar to one way to study the relationship of this virus with other isolated earlier from African yam-bean (soybean potyviruses observed in soybeans.-G. Thottappilly isolate 2), a new potyvirus that causes a characteris- and H. Huttinga 52 Grain Legumes Table 47. Results of host range tests with soybean that differences exist between the two. For example, Abuia virus. 1982 Vigna unguiculata (Ife Brown) is highly susceptible Plant species Reactiona to CYMV, whereas only a few necrotic lesions andno Betauulgaris . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - systemic symptoms occur with the Abuja virus. Also, Brassica sinensis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - TVu-4526, which is highly susceptible t o CYMV, did Canaualia ensiformis. . . . . . . . . . . . . . . . . . . . . . . . . . . . S not show visible symptoms with the Abuja virus. Chenopodium amaranticolor . . . . . . . . . . . . . . . . . . . . . L To determine whether the Abuja virus is trans- Chenopodium quinoa . . . . . . . . . . . . . . . . . . . . . . . . . . . L mitted through seed, Glycine max (Malayan) was Cucumis melo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - inoculated with the virus, and seeds were collected Cucumis sativus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - from infected plants. The 600 seeds were sown in an Cucurbita maxima. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - insect proof screenhouse and observed for symptoms Glycine mar (Malayan). . . . . . . . . . . . . . . . . . . . . . . . . . S for six weeks. Suspected plants were individually Glycine mar (Bossier). . . . . . . . . . . . . . . . . . . . . . . . . . . S inoculated to N. benthamiana, but no seed trans- Gomphrena globosa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S mission could be detected, although i t is possible that Lathyrus odoratus.. . . . . . . . . . . . . . . . . . . . . . . . . . S seed transmission occurs in other varieties.-G. Lycupersicon esculentum (Moneymaker) . . . . . . . . . . . - Thottappilly and H. W. Rossel Lycopersicon esculentum (Bonny's Beste) . . . . . . . . . . - Lycopersicon esculentum (Rutgers) . . . . . . . . . . . . . . . . - Microbiology Nicotiana benthamiana.. . . . . . . . . . . . . . . . . . . . . . . . . L, S Nicotiana cleuelandii. . . . . . . . . . . . . . . . . . . . . . . . . . . I, In 1982 soil microbiology research in the Grain Nicotiana megalosiphon . . . . . . . . . . . . . . . . . . . . . . . . . L Legume Improvement Program focused almost Nicotianaglutinosa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . exclusively on cowpeas. Field evaluation of cowpea Nicotiana tabacum (Samsun NN) . . . . . . . . . . . . . . . . . L rhizobial inoculants was begun in eight countries Nicotiana tabacum (White Burley) . . . . . . . . . . . . . . . . L, S (five African, one Asian and two Latin American). Nicotiana tabacum (Xanthii n.c.) . . . . . . . . . . . . . . . . . L Although not all trials have been completed, i t Phaseolus aureus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S appears a t this point that rhizobial inoculants are Phaseolus uulgaris (Bataaf). . . . . . . . . . . . . . . . . . . . . . L, S not likely to increase cowpea grain yield. Two Phaseolus vulgaris (Dubhele witte zonder drsad) . . . L, S inoculation methods were tested under two soil Physalisfloridana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - - fertility levels; granular inoculants seemed to be Pisum satiuum (Kelvedon Wonder) . . . . . . . . . . . . . . . S more suitable than peat inoculants for field use. The Pisum satiuum (Mansholt) . . . . . . . . . . . . . . . . . . . . . . . S effects of Rhizobiuminoculation and starter nitrogen Pisum sativum (Koroza) . . . . . . . . . . . . . . . . . . . . . . . . . S on early maturing cowpeas were investigated, and a Pisum sativum (Rondo). . . . . . . . . . . . . . . . . . . . . . . . . . S rhizobial strain that is effective i n early nodulation Solanurn melongena . . . . . . . . . . . . . . . . . . . . . . . . . . . . -- and initial growth of plants was found. Seasonal Vicia faba.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - . variation in the population sizes of indigenous Vignu cylindrica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S rhizohia in a semiarid tropical soil was examined, Vigna unguiculata (Ife Brown) . . . . . . . . . . . . . . . . . . . L and a nondestructive, inexpensive test for detecting Vigna unguiculata (TVu 4526). . . . . . . . . . . . . . . . . . . . - ureide compounds in plants was tested on cowpeas "I, = local symptoms, S = systemic symptom and - = no under field conditions in the tropics. infection, as determined by back inoculation. Testing of Cowpea Rhizobial Soybean Abuja Virus Inoculants A virus disease of soybeans (hamed soybean Abuja Inoculation trials were conducted a t three locations virus) that was originally found in the Abuja region in West Africa: Samaru in northern Nigeria, Maradi of Nigeria is characterized by chlorotic mottle, leaf in Niger and Kamboinsi? i n Upper Volta. VITA-7 was deformation and mosaic in soybeans and chlorotic grown a t each location along with a local check: r ing spots on inoculated leaves of Nicotiana cultivar IAR 48 a t Samaru, TN 88-63 a t Maradi and benthamiana, which later develop into systemic SUVITA-2 a t Kamboinsi.. Five Rhizobiunz strains symptoms (IITA, AnnualReport for 1979). were tested a t each location. Strains IRc 252, lRc In order t o study the host range of t he soybean 430A and lRc 500A were selected because of their Abuja virus, severa l t e s t p lant species were superior performance in preliminary trials (IITA, inoculated with crude juice from infected N. Annual Report for 1981). Strains NUM 716 and T 242 benthamiana. The results of host range studies were from the Microbiological Resources Centre i n determined by visual observation and back in- Nairobi were included to increase the diversity of oculation onto N. benthamiana (Table 47). strains tested under West African conditions. The Serological tests, using a n antiserum against the five strains came from Onne (Nigeria), Maradi, IITA, Abuja virus and CYMV as the test antigen, and tests India and Kenya. Each strain was used as a single with CYMV antiserum and the Abuja virus, revealed strain inoculant, except IRc 500A, which was a close relationship between CYMV and the Abuja included only in the mixed inoculant containing all virus. However, i t was observed in host range studies strains. Symbiotic effectiveness was evaluated by measur- Nodule dry wt. ( rng/plant) ing plant growth and nodulation 5 to 6 weeks after planting, and yield was measured a t maturity in relation to yields of uninoculated and nitrogen fertilized control treatments. Soil nitrogen content was very low a t all locations (0.021t o 0.075% total N). The competitiveness of inoculated strains was evaluated by typing nodules, using an enzyme linked immunosorhent assay (ELISA) technique for strain identification. At Samaru, although there were differences in nodulation between inoculation treatments, the uninoculated plants had the highest nodule mass (Figure 16). Results of nodule typing showed that inoculated strains were less competitive than Maradi indigenous strains. Inoculation had no significant VITA-7 ( i7.88-63 effect on yield (Table 48). At Maradi plant growth was poor because of inadequate soil moisture. Total rainfall in 1982 was 285.8 mm, almost 40% less than the mean annual rainfall for the past eight years. Nodulation and yield were greater in TN 88-65 than VITA-'7, indicating that the former is more adaptable to the environ- mental conditions a t Maradi (Figure 16 and Table 48). Inoculating plants did not significantly affect nodule mass (Figure 16). Inoculated strains were not competitive with indigenous strains for nodulation of either cowpea host cultivar (Table 49). Inoculation reduced the number of nodules per plant, and in- oculated plants produced the same yield as unin- oculated ones, suggesting that the inoculated strains may be symbiotically more effective than indigenous -$ & $ < S ? N rhizohia. Q 2 ~ 8 b 3 2 3.c 0 * z + .5 At Kamhoinsk soil moisture was not limiting. The 0 yield of VITA-7 was hieher there than a t the other .?- -* - @ I locations, and the cheik, SUVITA-2, outperformed 5 ' the checks used a t other locations ('fable 48). Flgure 16. Effect of inoculation on nodulation of cowpea Rhizobium strain IRc 252 was highly competitive cultivars at locations in West Africa. The m~~ix~t urp~ -c on- with indigenous rhizohia for nodulation of both tained equal proportions of the four strains. S.C. and D.C. cultivars (Table 49). IRc 430A was moderatelv com- are the values for com~ari-n em eans of the same and petitive. As a t Maradi inoculated plants ~ roduced differentc ultivars, respectively. less nodule mass than uninoculated ones (Figure 16), yet differences in plant growth and yield between Since 1979 we have isolated, screened and selected inoculated and uninoculated treatments were not effective and competitive rhizohia from diverse significant (Table 48). environments, and these have now been used in Table 48. Yield of cowpeas at three locations in West Africa, 1982 Samaru, Nigeria Maradl, Niger Kamboinsi., Upper Volta Treatment VITA-7 IAR 48 VITA-7 TN 88-63 VITA-7 SUVITA-2 &/ha Un~noculated. . . . . . . . . . . . . . . . . . . 1,090 610 330 1,040 2,000 1,980 N fertilizer. . . . . . . . . . . . . . . . . . . . . 980 640 540 1,090 1,980 1,900 Inoculated: IRc252 . . . . . . . . . . . . . . . . . . . . . . 1,050 500 360 930 2,000 1,720 IRc430A . . . . . . . . . . . . . . . . . . . . . 830 570 360 1,180 2,050 1,720 NUM716 . . . . . . . . . . . . . . . . . . . . 1,140 630 330 w'Ja 2,090 1,990 T242 . . . . . . . . . . . . . . . . . . . . . . . . 820 460 230 1,200 2,210 1,660 Mixture ..................... 1,060 550 360 1,150 2,060 2.030 LSD (5%): Same culhvar . . . ............. 300 370 420 Different cultivars . . . . . . . . . . . . 220 390 320 84 Grain Legumes 'l'i~hlc4. 9. I'l.opnrtion of noclult., formed hy inoculants in r o u p e u c~ulrivnrsa t thr6.1. lorations i n Weat .Afrirrt. 1982 S:~rn.al.uF. i lg , .~~: , - - - > l : ~ r ; a d i ~ Y i g ~ ~K : -~~ o l l ~ ~ . l nl'p, .1 1t.r \'13111 Inocuiant VITA 7 IAR 48 VITA-7 TN 8863 VITA-7 SUVITA 2 percent 1Rc 252 . . . . . . . . . . . . . . . . . . . . . . . . 41.2 7.1 43.3 9.5 89.2 90.0 IKc 43FA. . . . . . . . . . . . . . . . . . . . . . . 25.2 14.9 25.1 40.4 59.4 68.9 LSD (5%,): Same cultivar . . . . . . . . . . . . . . . . 40.7 63.5 50.7 Different cultivars . . . . . . . . . . . . 24.6 29.3 37.4 Note: Nodules were collected five or six weeks after planting extensive field trials in West Africa (IITA, Annual nutrients and farmyard manure (high fertility). Two Reports for 1979, 1980 and 1981). Based on that past Rhizobium strains, IRc 252 and 430A, were used as work and this year's results, we draw the following single strain inoculants. Both were found to be conclusions concerning the use of Rhizobium superior, based on their performance under field inoculants with cowpeas in West Africa. First, conditions (IITA, Annual Report for 1981). VITA-7 rhizobia in West African soils nodulate cowpeas and a local cultivar, TN 88-63, were the host effectively and fix enough atmospheric nitrogen to cultivars; shoot growth and nodulation a t six weeks support plant growth and produce good grain yields. after planting and yield a t maturity were compared Second, to increase symbiotic nitrogen fixation to t,hat of uninocnlated treatments, with and without under the high temperature and drought stresses N fertilizer. Nodules were analyzed by ELISA to that frequently occur in West Africa, i t is necessary evaluate competitiveness of inoculated Rhizobium. to find highly effective Rhizohium strains that Hot, dry soil conditions a t sowing reduced combine tolerance to desiccation and high tempera- germination considerably, causing plant stands to be ture with superior competitiveness for nodulation. generally poor. These stresses were favorable, Third, alternative methods of inoculation that are however, for studying the survival of inoculated more suitable to dry soil conditions are required if strains. Shoot growth and yield of TN 88-63 rhizobial inoculants are to be used. responded significantly to chemical nitrogen under low fertility (Figure 17 and Table 50). Nodulation did Inoculation Methods not respond to inoculation (Figure 18). Under high fertility growth and nodulation of TN 88-63 were Highly effective rhyzobia are useless unless, when improved. inoculation did not improve nodule mass, inoculated under farm conditions, they survive in the compared to that of uninoculated plants, but soil and infect the roots of the host plant. In addition Rhizobium strain IRc 252 improved the yield of TN to intrinsic characteristics of the inoculum, such as competitiveness against native rhizobia and toler- ance to adverse environmental factors, the form of Shoot fresh weight (g/plant) inoculum has a major effect on the survival and IU ninoculated overall effectiveness of inoculated strains. S N fertilizer 1 Results of past experiments showed that seed inoculation with peat powder based Rhizobium may not provide sufficient rhizobia for maximum in- fection. Therefore, a preliminary experiment was conducted at Maradi, Niger, to test the effectiveness of two inoculation methods at two soil fertility levels. Rhizohia were inoculated either by coating seeds with peat based inoculum (peat inoculant) or by adding a peat granule based inoculant to the soil underneath the seed (granular inoculant). Peat inoculants require that seeds be inoculated prior to sowing and also require special handling during sowing. Granular inoculants combine greater effec- tiveness with convenience of handling under field conditions; ahove all, they provide greater numbers of rhizobia per seed than powdered peat. Two fertility levels were established by either Low fertilizer High fertilizer low fertilizer High fertilizer adding 75 kg of singlc superphosphate per hectare, a common practice among farmers in the area, or VITA-7 TN88-63 adding 400 kg of single superphosphate, mnriate Figure 17. Plant growth of cowpeas at different soil fertility of potash and other fertilizers, including micro- levels, Maradi, Niger. 1982. Grain Legumes 85 88-63 a t high fertility, indicating i t s greater Table 50. Yield of cowpea cultivars grown a t different symbiotic effectiveness. fertility levels, Maradi, Niger, 1982 Growth of VITA-7 was adversely affected by VITA-7 TN 88-63 environmental stresses, but yields were improved Low High Low High under high fertility (Table 50). Inoculation, however, N source fert. fert. fert, fert. had no significant effect. Granular inoculants hglha increased the proportion of nodules formed by IRc Uninoculated . . . . 370 660 760 1,040 252 on VITA-7 (Table 51). Nodulation by IRc 430A on N fertilizer. . . . . . . 610 650 1,000 1.200 TN 88-63 was also improved by granular inoculant Inoculated with: under low fertility. High fertility decreased the 1Rr252 . . . . . . . . 450 550 8'20 1,410 competitiveness of the granular form of IRc 430A IRc 430A. . . . . . . 400 630 960 1,180 inoculant. The unexpected drought this year IBD (5%) . . . . . . . . 220 severely reduced plant establishment and growth, thereby preventing full evaluation of the effects of Table 51. Proportion of nodules formed on cowpeas fertility level and inoculation methods. This trial bv different Rhizobium strains at two will be repeated.-S. Asanuma and A. Ayanaba fertility levels, Maradi, Niger, 1982 VTTA-7. T- N 8~8- -6~3 Populations Sizes of Cowpea and Low High Idow High Soybean Rhizobia Inoculant form fert. fert. fert. fert. 1Rc 252 percent Variation in the population sizes of rhizobia that are Powder . . . . . . . . 0.8 0.0 0.5 2.3 capable of nodulating cowpeas and two soybean Granule . . . . . . . 27.3 26.0 7.5 16.1 cultivars with different symbiotic promiscuities was IRc 430A assessed in 1980 a t three locations (IITA, Onne and Powder . . . . . . . . 14.1 8.8 10.5 13.0 Maradi) tha t represent diverse soil types and Granule . . . . . . . 11.3 7.7 36.2 18.6 climates. IITA in southwestern Nigeria represents LSD (509 . . . . . . . . 16.8 the rainforest-savanna transition zone, where the Note: Rhirohium strains were inoculated as peat and granular soils are predominantly Alfisols. At Onne, located in inoculants. Nodules were collected fivr to six weeks after southeastern Nigeria in the rainforest zone, the soils are Ultisols with low Ca, high acidity, high ex- changeable aluminium and high rainfall. The soil a t Nodule dry weight (rng/plantl Maradi, Niger, in the Sahel savanna is sandy, low in N and available P and Ca, and subject to extremes of temperature and prolonged drought. Uninoculoted Soil samples were collected a t depths of 0 to 5 cm, 5 .... N fer+i,izer to 15 cm and 15 to 30 cm a t planting time, six weeks after planting and a t the end of the dry season in fields cropped to cowpeas during the rainy season and in uncultivated fields adjacent to the cropped area. Rhizobia were enumerated by the most probable number (MPN) method for microbial populations with 10-fold dilution series and five replicates per dilution. The plant infection test was used in growth pouches containing Jensen's solution. Cowpea cultivar ER 1 was used to enumerate cowpea rhizohia, the American soybean cultivar TGm 80 (Bossier) for Rhizobium japonicum, and soybean cultivar TGm 344 to enumerate rhizobia that nodulate soybeans with symbiotic promiscuity. IITA soils contained significantly more rhizobia Low fertlllrer Hlghfertilizer Lowfertilizer High fert~lirer than those a t Onne and Maradi (Table 52). Low rhizobia numbers at Maradi and Onne account partly for poor nodulation and corroborate our earlier Figure 18. Nodulation of cowpeas at different soil fertility observation (IITA, Annual Report for 1979) that the levels, Maradi, Niger, 1982. cowpea-Rhizobium symbiosis is less effective a t those locations. Because there were less than a thousand Numbers of rhizobia, especially of cowpea rhizobia rhizobia per gram of dry soil at Maradi, this location in the root zone (0 to 15 cm) six weeks after planting, should be suitable for cowpea and soybean inocula- were significantly higher in fields cropped to tion experiments, and there should be minimum cowpeas (Table 52). It thus appears that cowpeas competition between inoculum rhizobia and the build up the population of compatible rhizobia in the native populations. rhizosphere. 86 Grain Legumes Samples collected a t adepth of 5 to 15c m contained Table 52. Variation in population sizes of cowpea and more cowpea rhizobia than those from the surface soybean rhizobia according to location, soil (0 to 5 cm), especially a t IITA, where the cowpea cropping and soil denth. 1980 rhizohia were approximately three times more Rhizobium group numerous in samples from 5 to 15 cm deep than in Cowvea R. ;a- Promis- samples from 0 to 5 cm (Table 52). This difference was rhizo- poni- cuous expected since the surface soil layer (0 t o 5 cm) is hia cum rhizobia Mean subjected to various deleterious changes in tem- numberper gram of dry soil perature and moisture. There were few rhizohia in Maradi, Niger.. . . . . . . 780 4 208 331 samples collected a t a depth of 15 to 30 cm, and Onne, Nigeria.. . . . . . . 6,314 3 871 2,396 seasonal variation in rhizobia counts in that soil IITA . . . . . . . . . . . . . . . . 24,162 134 1,949 8.748 layer was always significant. Mean . . . . . . . . . . . . . . . 10,419 47 1,009 Differences in Rhizobium populations were highly LSD (5'jb) for: significant, the cowpea rhizobia being 10 times more Locations . . . . . . . . . . 5,264 numerous than the promiscuous rhizobia (so called Rhizobium groups . . 5,264 for their ability to infect soybean cultivars exhihiG Interactions . . . . . . . . 9.118 Cropped to cowpeas. . . 18.913 92 1,395 6,800 ing symbiotic promiscuity). R. japonicum, which is Uncultivated . . . . . . . . . 1,924 2 623 850 specific for the American soybean cultivars, had the LSD (5%) for: smallest population a t all three locations, confirming Fields . . . . . . . . . . . . . 4,298 that American soybean cultivars must be inoculated Rhizobium groups . . 5,264 with elite strains of R. japonicum in tropical soils. Interactions . . . . . . . . 7,445 The investigation of t he size and seasonal Soil depth variation in Rhizobium populations in Maradi soils 0 to 5 cm. . . . . . . . . . . 9,706 9 1,509 3,741 was continued during 1981 and completed this year. 5 to 15 cm . . . . . . . : . . 20,137 130 1,430 7,232 The annual rainfall in Maradi in 1981 was 412.9 mm, 15 to 30 cm . . . . . . . . . 1,413 2 89 502 distributed over the period from May t o September. LSD (5%) for: Soil depths. . . . . . . . . 5,264 The maximum daily temperature was 43'C from 19 t o Rhizobium groups . . 5,264 21 April, and the annual mean temperature was Interactions . . . . . . . . 9,118 27.2OC. Soil samples were collected from fields cropped Note: The numbers listed for cropping and soil depths are avernges for all three locations. with cowpeas and under natural fallow. Fields were sampled during the dry season (29 April), a t the beginning of the cropping season (9 July), during the throughout t he year and those of R. japonicum the season (27 August) and at the end of the season (30 smallest (Table 53). Rhizobial numbers, especially of September). Rhizobial populations were enumerated cowpea and promiscuous rhizobia, were high in the by the MPN method, using plastic pouches for the surface layer of the soil (0 to 15 cm). Population plant infection test. The cowpea cultivar VITA-7 and densities of those rhizobia increased slightly at all the soybean cultivars TGm 119 and 294-4 were used as depths in both fields a t the beginning of the cropping hosts for cowpea rhizobia, promiscuous rhizobia and season and were retained throughout the season, R. japonicum, respectively. particularly in the upper layer of the soil (0 to 15 cm). Populations of cowpea rhizobia were the largest This increase could have been caused by higher soil Table 53. Seasonal variation in population sizes and in spatial distribution of indigenous rhizobia, Maradi, Ni-g er, 1981 Rhizobium Depth, crn Cowpea Promiscuous R. japonicum 0 to 5 10 to 15 25 to 30 Total Durine drv" season ~~~~~ ~ Cropped . . . . . . . . . . . . . . . . . . . . . . . . 2,483 840 19 604 2,093 645 3,342 Uncropped . . . . . . . . . . . . . . . . . . . . <401 < 66 < 24 < 6 427 58 <491 Beginning of cropping season Cropped . . . . . . . . . . . . . . . . . . . 5,569 3,686 < 6 2,823 4,856 1,582 9,261 Uncropped . . . . . . . . . . . . . . . . . . . . . . -8 -- - - - - During cropping season Cropped . . . . . . . . . . . . . . . . . . . . 2,544 - < 6 1.023b 1.355" 17Zh 2.550h Uncropped. . . . . . . . . End of cropping season Cropped . . . . . . . . . . . . . . . . . . . . . . . . 1 174 < 115 < 6 100 189 <6 ~ 2 9 5 Uncropped. . . . . . . . . . . . . . . . . . . . . . 680 36 < 50 134 179 453 766 Note: Population sizes are cell numbers per gram of dry soil. ~ ~ aNot determined. bSum of population sizes of cowpea rhizobia and R. japonicum only; other totals are for all three groups of rhizobia. Grain Legumes 87 Nodule dry weight ( mg/plant 800, I - I T 8 2 E - 6 0 IT82E-71 IT82E-9 IT82E-18 TVx 3236 VITA 7 Cultivar Figure 19. Effect of nitrogen source on nodulation of early maturing and intermediate maturity cowpea cultivars at six weeks after planting, IITA, 1982. moisture content, lower temperatures, and addition Table 54. Effect of urea-N and inoculation with of organic materials from increased nlant .g,r owth. different Rhizobium strains on earlv ~ i t t l~d i f fe renicne s patial distribution and seasonal maturing cowpeas, IITA, 1982 variation was observed for R. japonicum. The Shoot drv Nodule drv No. of Ureide enumeration of indigenous rhizobia in Maradi soils weight weight nodules production during 1982is in progress.---S. Asanuma, A. Ayanaba 24 DAP,= 24DAP, per plant 24 41 and K. Mulongoy Treatment g/plant g/plant 24 DAP DAP DAP Uninoculated. 1.9 102.7 10 2.Zh 3.0 Effect of Nitrogen Fertilizer and 20 kg N/ha . . . 1.8 49.3 6 2.0 3.4 Rhizobium Inoculation on Cowpeas 80 kg N/ha . . . 2.1 52.8 7 2.7 3.6 Inoculated: Four early maturing cultivars, TVx 3236 and VITA-7 IRc 430A. . . 2.1 145.5 14 2.9 4.2 were grown either with Rhizobium inoculation or IRc 500A. . . 1.4 131.7 15 2.4 3.5 with urea N to test the ability of inoculated strains to LSD (5%) . . . . 0.4 36.6 4 0.4 0.6 improve early nodulation and yield of symbiotic plants and to determine the effects of starter N (20 "Days after planting. bUreide production was measurod by a simple colorimetric spot kg/ha). We tested inoculants from two single strains, test, which qualitatively estimates allantonate levels in the plant IRc 430A and IRc 500A. In laboratory and greenhouse on a scale of 0 to 6 , c orresponding to 0 to 64 mM Na~allantonate. trials, both showed superior ability to form early, effectives ymbioses with cowpeas. in nodulation by indigenous and inoculated strains Four weeks after planting, inoculation with IRc (Figure 19). Nodule dry weights in IT 823-18 were 430A and IRc 500A significantly increased nodule greatest in the uninoculated treatment; IRc 430A number and dry weight in all cultivars compared to significantly increased nodulation of IT 823-71; and that of uninoculated plants. Growth of plants IRc 500A increased nodulation of VITA-7. Nodule dry inoculated with IRc 430A was comparable to that weight correlated well with nodule number (r = with the highest N treatment, although IRc 500A 0.79). Plant growth was affected by drought reduced growth, compared to that of the unin- throughout the experiment, and as a result yields oculated treatment. were low. Cultivars IT 823-60, 823-71 and 823.9 Six weeks after planting, shoot growth in all averaged 475 kg/ha; IT 823-18, TVx 3236 and VITA-7 treatments was similar, and nodulation in unin- averaged 950 kg/ha. oculated treatments had generally increased com- A spot test for ureide production was done four and pared to that in inoculated treatments. Both N six weeks after planting (Table 54). Ureide levels in treatments, however, still depressed nodulation. all cultivars rose over that period. In both spot tests, There were significant differences between cultivars inoculated plants, especially those inoculated with 88 Grain Legumes 1Rc 430A, had higher urcide levels than either the uninoculated or 20 kg N/ha treatments. But in plants given 80 kg N/ha ureide, production was comparable to that in well nodulated plants, even though fertilizer N greatly reduced nodule number and weight. Rhizobium strain 1Rc 430A increased early nodulation and initial growth of early maturing cowpeas. Plants inoculated with i t had similar growth four weeks after planting and about the same yield a t harvest as plants given 80 kg N/ha and showed high ureide production. Further studies need to he carried out under nonlimiting conditions. S. Asanuma, A. Ayanaba and R.B. Singh Studies on a Cowpea Cross- Inoculation Group In continuation of studies on population sizes of cowpearhizobia in soils at IITA and Fashola, Nigeria (IITA, Annual Report for 1981), rhizobial isolates were physiologically characterized, and inoculation trials were conducted to evaluate the symhiotic effectiveness of those isolates under field conditions a t the two locations. Acid tolerance (measured by ability to grow on agar plates a t pH 4.5) was influenced by temperature, phosphorus level, and strain origin. A higher pro- portion of isolates from grain lcgumes (72%) than from forage legumes (36%) were acid tolerant, particu- larly those from IITA. Acid sensitivit!~w as increased by increasing temperatures from 30° to 37' C, and lowering phosphorus levels from 1,000 to 5,'M. Thc low P treatment is representative of P levels commonly found in the soil solution. Of the 98 isolates tested, 29%, were tolerant of low P a t pH 4.5. Three grain legumes (cowpeas, grouudnuts and pigeon peas) and three forage legumes (Centrosema, Leucaenu and Psophorarpus palustris) were in- oculated with isolates from each legume grown in the field a t IITA and Fashola. Uninoculated treatments with and without nitrogen fertilizer were included. At both locations, Leucaena did not nodulate with isolates from other legumes or with native rhizobia, whereas nodulation and effective symbioses in other lcgumes did occur with any of the isolates tested and with indigenous rhizobia. Cowpea yield at IITA was improved by Nfertilization and by inoculation with a cowpea rhizobial isolate. The growth of forage legumes a t Fashola was much poorer than a t IITA. Further studies of soil fertility are in progress. The residual effects of the Rhizobium-legume symbiosis on soil fertility were measured by growing maize after harvesting the legumes. Maize growth was grcatest following cowpeas or groundnuts. Nodule typing to evaluate competitiveness and survival of inc~cul;~tesdt rains is in progress.-- A. Ayanaba and M. Mafuka Roots and l'ubers 91 T 11c nooT AND TUBER Improvement Program to both cassava mosaic disease and bacterial blight (TRIP) is engaged in the improvement of four (Figure 1). These improved varieties arc undergoing root crops --cassava,y ams, sweet potatoes and yield trials a t various locations in Nigeria anrl are cocoyams-that are basic in the-diet of most people in being sent in both seed and tissue culture form to the less developed tropical nations. These crops are national programs in Africa for multiplication and the main source of food for the rural and urban poor distribution to farmers. (although crops such as yams are often the preferred food and command a premium price) and production Variety Trials of them is the main livelihood of many small scale farmers. Improvement in production would thus Yield trials of 12 llTA improved varieties were greatly benefit both producers and consumers. conducted without fertilization at three locations in The ultimate goal of TRIP'S scientific team is to Nigeria - Onne, IITA and Mokwa-that represent a develop improved varieties that have pest and wide range of environmental conditions. Onne is disease resistance, produce high and stable yields, located in the high rainfall zone and has sandy, poor give superior economic returns to the producer, and soil; Mokwa is in the dry savanna; and IITA have good consumer acceptance. An essential part of represents the region of moderate rainfall and soil the scientists' work is to transfer this technology fertility. Trials of common cassava varieties were to farmers by training scientists from national discontinued a t these locations this year because of programs and by providing close and continuous an outbreak of cassava green spider mite (CGM) and support. In 1982 the program made significant cassava mealybug (CM). progress both in crop improvement and technology TMS 50395 performed outstandingly a t all lo- transfer. cations, producing the highest average fresh yield (26 t/ha), followed by TMS 40081, TMS 4(2)0267 and Cassava TMS 50207. TMS 50395 yielded more than 4.6 times the yield of the standard variety, 60508, which was Cassava, because of its importance in the African formerly the best Nigerian variety and was used as a diet and its social and economic significance, con- parent a t the outset of IITA's breeding program. TMS tinued this year to receive highest priority. The most 30337 and TMS 4(2)0267 performed well under high pressing problems with this crop at present are the rainfall, sandy soil conditions. The IITA improved var- mealybug and green spider mite, which are causing ieties outyielded the standard variety at all locations. devastating crop losses all across Africa. We are TMS 50395 also showed resistance to both cassava hopeful that these losses can be checked through a mosaic disease (CMD) and cassava bacterial blight combination of biological control and breeding of (CBB) as well as tolerance to both CGM and CM. The resistant varieties. Success in mass culturing and field establishment Yield ( t/ha Disease score of natural enemies of the mealybug has justified 20 5 projects for large-scale rearing of these enemies and distribution of them on the ground and by aerial drop if this method proves to be feasible. Since distri- bution will he done in coo~erationw ith national programs, much emphasis is being placed on training of nationals in biological control methodology. High priority 1s also being given to incorporation of resistance to the mealybug and green spider mite into cassava varieties that already have genes for resistance to cassava mosaic disease and cassava bacterial blight as well as good agronomic quality. Other important projects in cassava research are the screening of germplasm for resistance to anthracnose disease and tuber improvement work aimed a t reducing HCN content and improving starch quality. Genetic Improvement 00- 4 1971 72 73 74 75 76 77 Since the beginning of IITA's cassava breeding Figure 1. Mean yield and disease resistance scores of program in 1971, significant progress has been made improved varieties since the beginning of IITA's cassava in developing high yielding varieties with resistance improvement program. 92 Roots and Tuhrrs Tahles 1. Performance of cassava varieties a t various locations in Nigeria, 1981-82 percent ~ r y Disease Pest Frcsh yield. t/ha dry yield resistancea resistance" Gari Garification Variety llTA Mokwa Onne Avg. matter t/ha CMD CBB 'GM CMB qualityb rate, % TMS 50395.. . . . . 27.3 32.0 18.4 25.9 35.5 6.6 1.8 1.7 2.0 2.0 G 16 TMS 50207. . . . . . 18.5 11.2 16.0 15.2 TLWS3 0337 . . . . . . 17.4 5.0 20.7 14.4 TMS 30001 . . . . . . 14.4 15.5 11.8 13.9 TMS 30211 . . . . . . 12.3 12.0 14.6 13.0 TMS 30572 . . . . . . 16.6 7.1 14.3 12.7 TMS 30555 . . . . . . 10.1 15.9 11.0 12.3 TMS 4(2)144:1. . . . 12.0 2.6 13.7 9.4 TMS 50193 . . . . . . 13.0 2.4 18.4 11.3 60506 (check). . . . 5.6 3.0 8.3 5.6 LSD (5%) . . . . . . . 5.35 9.15 6.20 4.05 S.E . . . . . . . . . . . . . 1.86 3.17 2.15 1.44 "Resistance to cassava mosaic disease (CILID). bacterial blight (CBB). grecn spidcr mite (CUM) and mealybug (CMB) was rated on a 1 to 5 scale, where 1 = no damage and 5 = sevcrr damage. "Uan quality was rated as follows: V(: = very good, G = good, M = moderate and P = poor. quality of gari made from the tuberous roots of this agriculture and privat,e organizations. According to variety was rated as good. The variety had ;i lower recent reports, these improved varieties are now percentage of dry matter and a lower garific at l' on planted on more than 80,000 hectares. They give rate than did other IITA improved varieties. But its farmers several advantages over the local, un- total dry yield was the highest of the varieties tested. improved varieties: their yields are 50 to 300'%,h igher TMS 4(2)0267 had the highest average percentage and more stable because of their resistance to CMD of dry matter, 32.1'%,, followed by TMS 30572 with and CBR; their more rapid canopy development 30.1'%,. TMS 30001 (which had a lower cyanide speeds recovery from CM and CGM at,tack a t the content than the other varieties), TMS 4(2)1443 and onset of the rainy season; they require only a third as 4(210267 had high garification rates, ranging from 20 much weeding; and they have better processing to 21%. TMS 50207, TMS 30572 and TMS 4(2)1443 had quality. Demand hy farmers for planting material of very good gari quality (Table I). these varieties was quite high in I982 and is expected to increase in the years ahead. Multiplication and Distribution of S i e r r a Leone.The new varieties NUCASS 1 ,2a nd Improved Varieties 3, yields of which range from 9.7 t o 25.5 t /ha (two to During 1982 the highest yielding IITA variety, TMS four times the yield of the local variety Cocoa) were 50395, and the CGM and CM resistant varieties TMS multiplied a t five locations and distributed to local 4(211425 and TMS 60142 were multiplied on 20 ha in farmers with financial support from the U.S. Agency cooperation with the National Seed Service of for lnternat,ionalD evelopment (USAID). In addition. Nigeria. The improved varieties will be supplied to a large quantity of select planting material was sent s tate ministries and other nuhlic and nrivate to Guinea. organizations in Nigeria for further multiplication Zaire. The National Manioc Program (PRONAM), and distribution. which cooperates with IITA and is financed by Ilnprovcd IITA breeding material in hoth seed and USAID, has released two improved varieties- tissue culture form has been sent to many national Kinuani (30085128) and Kivuvu (30070/4)--that have cassava improvement programs in Africa for re- performed well in multilocational tests in the last selection under their environmental conditions. several years. Both were selected from TITA breeding Using this material. several national programs havc material and are particularly resistant to CBB, developed and released their own improved varieties. which has caused severe yield reductions and The paragraphs below discuss some of the accom- unstable production in Zaire. Kinuani is also plishments of these progrzims this ycar. resistant to CGM. The two varieties, which have high Nigeria. Five improved varieties-TMS 30572, consumer acceptance because of their good tuber and 30555, 30337, 30001 and 30211-have been rapidly leaf quality, havc been rapidly multiplied on a large multiplied and distributed to thousands of farmers scale and distributed to extension agencies and through the National Accelerated Food Production farmers. Projcct (NAFPP), National Root Crops Research Gabon. In 1981 and 1982, four improved varieties Institute. National Seed Service, state ministries of were increased by more than 400,000 cuttings and 94 Roots and Tubers Table 2. Relation between the pubescence character and CGM resistance in nine families of crosses between parents with vary.ing- deg.ree s of pubescence. IITA. 1982 CGM resistnncc score" Average Cross and pubescence 1 2 3 4 5 Total score X' Probability Pubescent with pubescent types TMS 60142 x TMS 4(2)1425 Present . . . . . . . . . . . . . . . . . . . . . . Absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TMS 60142 x T M S 60142 Present. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ahsent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nonpubescent with pubescent types TMS 30372 x TMS 60142 Present . . . . . . . . . . . . . . . . . . . . . . . . . . Absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TMS 30572 x TMS 4(2)1425 Present . . . . . . . . . . . . . . . . . . . . . . . . . . . . Absent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . TMS 30001 x TMS 4(,2 ,)1 425 Present . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ahsent. . . . . . . . . . . . . . . . . . . . . . . . . . . . TMS 30001 x TMS 60142 Present . . . . . . . . . . . . . . . . . . . . . . . . . . . . Absent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TMS 30555 x TMS 4(2)1425 Present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ahsent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nonpubescent with nonpubescent types TMS 30572 x TMS 30001 Present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0 0 20 25 45 4.6 TMS 30572 x TMS 30555 Present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0 0 0 0 0 - Absent.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0 2 13 21 36 4.6 Note: The X2t est was used Lo determine dependence between the pubescence character and CGM resistance scores =CGM resistance was rated on a 1 to 5 scale, where I = most resistant and 5 = most susceptible. Effect of Drought Stress on CGM duct detailed studies on the bionomics of CM and its Resistance exotic natural enemies. investigate host alant-insect interactions, and prepare forth; ~ f r i c a - w i dPer oject During the dry season, CGM damage and drought for Biological Control of Mites and Insect Pests in stress were rated subjectively in plants of variety TMS Cassava (AP-BC). 30572 planted along a contour under different soil moisture regimes. A total of 20 samples, each Both CM and CGM have continued to spread consisting of tive plants, were taken a t random in the throughout the African cassava belt (Figures 2 and field. CGM damage and drought stress were rated on 3). At present, some 4.5 million ha are infested with a 1t o 5 scale, with 1 being the least and 5 the greatest one or both pests. The annual loss is currently damage. CGM damage scores were related to drought estimated to he some $1,800 million, not including the stress ratings with a correlation coefficient of r = leaf vegetable protein andplantingmaterial lost. The 0.76, indicating that drought stress increased CGM rapid spread of and tremendous losses caused by damage. -S.K. Hahn and E.M. Chukwuma these pests have prompted IITA to speed up mass production of beneficial insects, which have shown promising results in natural enemy release trials, in Entomology preparation for the AP-BC. IITA's program for biological control of the cassava mealybug (Phenacoccus manihoti, MAT-FERR.) was Follow-up on Previous Releases of Natural continued more or less according to plans outlined in Enemies the IITA Annual Reports for 1980 and 1981. The The methodology of these releases was described in principal activities of the program this year were to the IITA Annual Report for 1981. Figure 4 compares follow up on 1981-82 releases, make new releases, the population density of CM in a field where natural carry out mass culture of beneficial insects, explore enemies were released with that in a field without for and introduce new natural memy species, con- natural enemies over a cassava growing period of 17 'z86L pue IL61 UaaMqaq ('dds s n ~ l a y 2 L u o u oa~l!m) ~ a p ~udaas1. 8 eaesseajo pea~di:.z a~nZr,q 96 Roots and Tubers sp. and A. lopezi showed the difference in their 1 potential for CM control. At hixh CM -p o-p ulation densities, Scymnus sp. predominates, as is usual for coccinellidae. A. lopezi, although present when the CM population is high, provides most of t,he control after the CM population has been brought down from damaging levels to subeconomic levels. In future releases, only A. lopezi will be released where the CM population is low and both Scymnus sp. and A. lopezi where i t is high. At IITA these two beneficial insects have spread as far as 2 km from the area of release within 12 months. Under farmers' field conditions, the natural spread might he reduced since fields are usually smaller and Dec 981 1982 are surrounded by fallow land and/or forest. Natural ~ R " ' ~ ~ ~ " - ~ ~ s ~ s o n ~ R " n ~ ' e"ne"mi"es" wi ll be carried out of old fields into new ones Figure 4. Population density of'cassava mealybug with and on the cuttings to assure control in every without release of natural enemies, IITA, 1981-83. colonized clearing-H.K. Herren and K.M. Lema months. The CM population in control fields in- creased drastically in March, but that in the release New Releases of Natural Enemies field dropped significantly within two months below From October to November 1982, releases of Scymnus the low lcvel that is normal during the rainy season. sp. and A. lopezi were made in farmers' fields. In two From March 1982 through January 1983, the CM plots (0.25 and 0.3 ha) a t the Texagri farm in population remained at the very low level of 1 to 5 Abeokuta, Nigeria, the natural enemies got estab- mealybugs (all instars) per terminal shoot, which is lished within six weeks, and after only 8 to 10 weeks roughly half the usual, low, sustaining population had practically eliminated CM from the field. They density during the rainy season. spread to neighboring fields until they were stopped There has been a shift in the numhcrs of each by fallow land and forest, by which time they covered natural enemy species present. From Decemher 1981 a total cassava area of 32.4 ha (Figure 5). to February 1982, Scymnus sp. was the predominant Natural enemies were released, either as adults species, and Apoanagyrus lopezi occurred only in carried to the field in petri dishes or as immature relatively small numbers. But between March 1982 insects (with a few adults) on infested cassava plants. and January 1983, A. lopezi became the predominant At Aheokuta, 1,500 adult Scymnus and 2,050 A. lopezi species. The first release experiment with Scymnus were released on three occasions, and an unknown Figure 5 . Dispersal of Apoanag,yrus lopezi, an exotic parasitoid of the cassava mealybug, in two release fields near Abeokuta. Nigeria, 1982-83. ~ o s s o v oI field h -4 1 corsdia field 0 Observation sites fr 45". Observation stes with Apoonogyruslopai N - 98 Roots and Tubers explorations in Brazil. Since that country is most temperature. It was longest (37.35 days) a t 20°C and prohahly the center of origin of CM, the chances a re shortest (17.05 days) a t 30.5OC (Table 3). good that the greatest diversity of natural enemies The different rates of population increase are also will he found there.-H.R. Herren, B. Loehr and A.M. shown in Table 3. The gross reproductive rate Varela reached a peak (695.02 eggs per female) a t 23.5'C, whereas the net reproductive rate (R,), which is the Influence of Constant Temperatures on gross reproductive rate corrected for survivorship, Population Growth of CM reached its peak a t 20°C. The mean generation time Preovipositing cassava mealybugs from crawlers (first instar mealybugs) that had been used in life Table 3. Effect of constant temperatures on cycle studies were chosen for life table experiments. demoeravhic statistics of Phenacoccus Potted cassava plants (of IITA clone 30001) were rnanihiti ;eared on cassava, IITA, 1982 infested with crawlers, and four plants were placed Temperature, C in Conviron E l 5 growth chambers, each set a t a different temperature (20°, 23.5", 27' and 30.5'C) and Statistics (X k S.E.) 20° 23.5- 27' 30.5' a relative humidity of 65 to 75%, with a 12-h Number of photophase. Twenty female mealybugs were placed observations.. . . . 20 20 20 20 in each chamber. After oviposition started each Mean adult longevity, days.. . 38.40 22.75 19.95 18.35 mealybug was observed every 24 h until i t died. The (21.78) (k1.31) (k0.87) (20.81) eggs were removed with a camel hair brush and No. of days until counted under a binocular microscope. Mortality of 50% mortality . . . 37.5 21.5 19.0 19.0 the immature stages was negligible. Mean fertility, Fertility and longevity data wereused to construct eggs per female . . 584.65 571.55 443.15 425.30 the survival and fertility tables for particular ages ( 2 2 9.43) (242.28) (f2 1.98) (h25.88) and to calculate the following statistics: (1)x , the age Mean oviposition of individuals in days; (2) I,, the proportion of period,days . . . . . 37.35 21.40 18.60 17.05 individuals still alive a t age x; (3) m,, female (?1 .81) (?1 .31) (k0.83) (k0.82) Gross repro. mte, offspring per female (only female offspring are offspringf ern. . . . . 656.20 695.02 482.77 458.97 produced by P. manihoti); (4) gross reproductive rate Net reproduction or number of female eggs per average female, not rate, offspring/ t,aking into account survivorship: (5) net repro- fem./generation . . 584.61, 573.36 443.25 426.30 ductive rate (R,) or number of female progeny per Innate daily rate female per generation (R, = 1, m,); (6) r,, intrinsic of increase . . . . . . 0.114 0.169 0.185 0.182 rate of natural increase calculated from the formula Generation time, ~e~ 'mXl ,m,= 1; (7) generation time (T) or mean days . . . . . . . . . . . . 55.89 37.58 32.94 33.27 length of a generation from birth of parents to birt,h Finite rate of' of offspring (T = l,R,/r,); and (8) finite rate of increaseper week . . . . . . . . . . . 2.21 3.26 3.65 3.45 increase (X) or multiplication per female per unit time (A = erm). Tahle 3 shows the influence of temperature on Age-speclflc fecundily rote 1 rnx) Adult surulwl mfe i 1x1 60 demographic statistics of the cassava mealybug. ----- - -. There was an inverse relation between adul t longevity and temperature. The adult life span was 40 ~ a f e orf Pmmonnnn highest a t 20°C and decreased sharply as the Adult P U ~ V L Y O ~ temperature increased. Survivorship curves a re h 2 0 -,. t 04 shown in Figure 6. At each experimental tempera- ture, all resemble Pearl's type I curve, with very little mortality a t younger ages but increasing mortality 0 0 as mealybugs get older. The time required for the population t o reach 50'2, mortality (LT50), which also expresses: the effect of temperature on longevity, was estimated from survivorship curves. This statistic also decreased with increasing temperature. Except a t 20°C the daily mean fertility (m,) was highest on the first day of the reproductive period and declined thereafter (Figure 6). At 20°C daily fertility was highest on the second day of the reproductive Reproductive perlod i days1 period. The total mean fertility was highest (584.65 Figure 6. Effect of temperature on age-specific fecundity eggs per female) a t 20°C and lowest (425.30 eggs) a t and adult survival rates of Phenacoccus maniholi, IITA, 30.5"C. Theovipositionperiod was greatly affectedb y 1982. Roots and Tubcrs 99 was also inversely related with temperature but was of rma nd the increase in the value of T at 30.5OC may higher at 30.5' than at 27'C. The intrinsic rate of indicate that constant temperatures above 30.5'C are increasewas lowest (0.114) a t 20°C and highest (0.185) unfavorable for development and population growth a t 27'C. The weekly finite rate of increase rose from of the cassava mealybug. The net reproductive rate 2.21 a t 20°C to 3.65 a t 2I0C before decreasing to 3.45 a t a t those temperatures was high. This may explain the 30.5"C (Table 3). capacity of P. manihoti to build up its population The inverse relationship observed between adult rapidly to explosive levels in the field during the longevity and temperature can be explained by the favorable dry season . K.M. Lema and H.X. Herren fact that longevity is generally inversely pro- portional to the intensity of life or metabolic rate of an insect. A higher rate of metabolism and activity Bionomics of Two CM Predators a t high temperatures causes the insect to reach senescence and die earlier than a t low temperatures. These bionomics studies are concerned with the Oviposition was maximum a t 2OoC because the adult developmental periods of the immature stages and life span is longest and the reproductive period is with the fecundity and life span of the adults. Five- prolonged a t that temperature. hour-old eggs from each of the two predators The innate capacity for increase and other related (H. notata and Sympherobius notata) were placed statistics determined in laboratory studies are based individually in separate petri dishes. Each egg was on the assumption of an ideal environmcnt that surrounded with ovisacs and other stages of CM. The differs from natural situations. It is, therefore, petri dishes were then placed in Conviron Model El5 difficult to apply laboratory results directly to field growth chambers under constant temperatures of populations, which are under the influence of natural 16.5', 20.0°, 23.5O, 27.0°, 30.5' and 34OC and a enemies, have limited food and space, and are fluctuating temperature of 2Z0 to 30°C ('$26.8). Daily exposed to adverse weather. This statistic is observations were made on the various develop- nevertheless a useful bioclimatic index that provides mental stages of the three predators. a good estimate of the maximum rate of' increase a This research is still in progress. So far, data have population can attain and of the range of tempera- been collected on the mean and range of develop- tures within which a species can persist and increase mental periods (Table 4), rate of development, lower in number. temperature threshold and thermal constants re^ The results of this experiment indicate that 27'C quired to complete the development of each stage. was the optimal temperature for population growth We also have data on the daily oviposition rate, of P. manihoti; the highest value of rm was observed fecundity and fertility, gross and net rate of at that temperature. The results also suggest that P. reproduction, instantaneous and finite rate of in- manihoti can persist and increase in number between crease, and generation time, which will be published 20° and 30.5"C; the value of rm in that range was upon completion of the research.-H.R. Herren and greater than zero. However, the decline in the value H.D. Nsiama She Table 4. Mean duration of developmental periods of im mature stages of cassava mealybug predators at various temperatures. IITA, 1982 Fluctuating Constant temperature, C temperature 16.5' 20.0° 23.5' 27.0' 30.5' 34.0° (22' to 38'C) Hyperaspis notata days (number of indiuiduals) Egg . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.0(61) 10.2(75) 69( 84) 5.0(24) . . . " 0" (143) 6.4(73) lnstar 1 . . . . . . . . . . . . . . . . . . . . . . . . . 4.0(15) 3.8(15) 2.0(20) . . . 2.1( 11) Instar 2 . . . . . . . . . . . . . . . . . . . . . . . . . 4.0i14) 2.5(15) - 1.9i20) . . . 1.7( 8) - Instar3 . . . . . . . . . . . . . . . . . . . . . . . . . Instar4 . . . . . . . . . . . . . . . . . . . . . . . . . Pupa . . . . . . . . . . . . . . . . . . . . . . . . . . . Egg to adult. . . . . . . . . . . . . . . . . . . . . Sympherobius notata Egg . . . . . . . . . . . . . . . . . . . . . . . . . . . . Instar1 . . . . . . . . . . . . . . . . . . . . . . . . . Instar2 . . . . . . . . . . . . . . . . . . . . . . . . . lnstar3 . . . . . . . . . . . . . . . . . . . . . . . . . Pupa . . . . . . . . . . . . . . . . . . . . . . . . . . . Eeetoadult . . . . . . . . . . . . . . . . . . . . . =Experimentn ot yct set up. ''1lMS: mortality. "Experiment in progress. dFirsti nstar larvae were transferred at hatching from 23 .F to 34'C since freshly hatched larvae had 100°/, mortality at 34% 100 Roots and Tubers Host Plant-Pest Interactions CGM in the entire area over which t,he two pests have Research on host plant-pest interactions is of spread, which includes 4.5 million ha throughout the primary importance in biological cont,rol, or in any African cassava belt. The exotic natural enemies will pest control program for that matter, because i t be mass reared a t IITA and released by air and from establishes the time and manner in which the damage the ground in all countries requesting them. The occurs, the plant's reaction to the damage, and the project will also provide training in biological effect of this reaction on mite and insect pests and control practices for 56 entomologists.-H.R. Herren eventually on the natural enemies of those pests. Understanding host plant-pest interactions better Pathology enables us to analyze the impact of biological control since i t pernlit,s us to separate the effects of biotic and Etiology of Anthracnose abiotic factors on yield losses. These losses depend not only on the pest's population density, but also on The objective of this study was to determine the role the plant's resistance to water stresses, its vigor, its of Pseudotheraptus deuastans, a sap feeding bug age when attackcd, the age structure of the pest commonly found on cassava, and of Colletotrichum population and other factors. gloeosporioides f. sp. manihoti.~in severe outbreaks of Recause of the complexity of these interactions, cassava anthracnose disease (CAD). mathematical models are being developed that will The following treatments were applied to one- enahle us to quantify and understand more clearly month-old plants of the clone TMS 30001: (1) the interactions between the host plant, the pest inoculation by the inoculum (1 x 10" spores per ml) insects, their natural enemies and the environment. spray method, (2) inoculat,ion followed by P. Thcse models can also be used to make control deuastans feeding (three hugs per plant), (3) feeding act.ions, such as release of natural enemies, as followed by inoculation, (4) feeding alone, and (5) no effective as possible. feeding and no inoculation as a control. The plants The purposcs of the research being undertaken are were arranged in a completely randomized block to develop a growth model for cassava, assess pest design, with four replications (five plants per damage in relation t o planting time, age of the plant treatment). The percentage of cankers infected, when attackcd and environment, and to develop a length of the cankers and amount of defoliation were sampling plan for CM and CGM. recorded for two weeks from the fourth day after For development of the model, two varieties of plants were treated. cassava were selected -a glabrous variety, 30572, The control plants remained completely healthy and a pubescent one, 60142. The varieties were throughout the period of observation. P. deuastans planted on 15 July 1982 and 15 September and 15 feeding followed by C. gloeosporioidesf. sp. manihotis April 1983. each in four plots, with 600 plants per plot inoculation and the reverse caused a significantly (600 m' plus border rows). The treatments are: higher percentage of cankers to be colonized by the infestation before first branching, infestation after fungus than did other treatments (Table 5). Plants on first branching, infestation after second branching which the fungus alone was applied showed no and insecticide sprays to keep control p1ot.s insect, typical anthracnose cankers. When hug feeding bee throughout t,he growing period. For the phenology model. data on internode length Table 5. Effect of C. manihotis inoculum and P. deuastans feeding upon infected cankers and leaf size are being gathered weekly from 10 on cassava plants, IITA, 1982 representative plants in the control treatment. In each of the four treatments, five plants a re collected Percentage of Length each month (roots, stem and leaves) for assessment of rnnkers infected after: ,,fCan~ dry matter and of thc number and distribution of CM. Treatment 4 days 8 days 12 days kcrs, mma Every week soil samples are collected to determine P. deuastans feeding the soil moisture. The climatological data for t,he alone . . . . . . . . . . . . 0.1 1.1 15.5 11.9 experiment arc taken from the IITA weather bullet,in. P. d~r,astarzfse cdine + C. manihotis This research is still in progress; the results will he inoculation . . . 82 .0 93.9 99.4 18.0 published after completion of a one-year growing C. manihotis inocula~ cycle.--H. R. Herren and F. Schulthess tion +P, deunstnns feeding.. . . . . . . . . 69.4 89.5 96.2 14.9 Africa-Wide Project for Biological Control C. mnnihotis inocula- tion alone . . . . . . . . 0 0 0 0 Because such promising results have been achieved Control . . . . . . . . . . . . 0 0 0 0 with t.he release of exotic natural enemies of CM at lITA, an Africa-wide project has been designed, and funds are now being sought for it. The International Fund for Agricultural Development (IFAD) has **Significarrt a t t h e l'x, level. helped greatly in preparation for the five-year :'Each valur is the mean uf four replications and indiuatrs the project. It will involve biological control of CM and cank~r1 engt.h four days aftw plants were treated. 'uo!?r[naou! z a p s hep uanas az!s uo!sa[ a$en!pu! q e p aq& .s?ioy?unw d s 2 sapplq~odsoaop?u rny3!dioia,(u3 jo sa?e[os~aa lq? qllM uo!pqnaout oa$!n u! o$ sauoIJ uhsssra 11 jo asuodsax ' L am3!d sau013 DADSSDD .uo!lnq!qslp a[qntleA Lpnls az!s ay& ' p o ~ ~ a d o ~ oy-qZdI n Lapun 3 0in ~Joln~qns u! pun L i~ [ !qe !~ae~a n p a ~o l saldares .1a9.1e[ uo s s a ~ B o ~ d ue u! paauld azah ?eq$ saaqureqa p!urny u! p a a u e ~ ~ e u! s1 y ~ .[eourJou~ 7ou seM pa!pnls B u y a1qt.1.1~~ aJaM saaa!d uaqs paqe[naou~a yA -palolpalnaqa lpaau aq+ ?nql pa~eaddn1 1 'squaurleall Buomn L?![rqc!~en w y l ! u~o! 8a.1 [epouLalu! aq? u1 apetu sa.mlaund a a q t[B1r[ ayl JO asneaaq $[nag!p s e s!~s.i[ eun [e3!ls!le?s JO dnolB e uo snaunj ay l jo Kuo[o3 BU!MOJB b[ah!qa~ pa[!elan 's7lnsaJ a?e~paur~a?up!a Moqs sleh!q[nn ue $0 sas!p urm@ Buq!sodap Lq pale[naou! pun raqqo aq,L . u e X ~ y u n y ~ upnuse~ 1 000~S ~ Juo, ~ a l z o y s 'a7nutm auo JO,J ~oyoa [ slL q7a %96 u! maql Bu!ddrp bq SSSOF S ~ PAUB ZLSOE SMT,T~,0 1aauo1 aq o? paz![!m"l aaejzns 'p[ag ayl ur ButmozB slue[d UIOL,J 77173 papual uo!sa[ a 8 e a a ~ eay L ' ( L aana!&) sauofa r?ilF!ssua azak 3uol ura 8 lnoqe saaa!d ua?s nilussea uaaa3 luara&!p aql 2uoure b[qu.zaprsuoa pa!auA az!s uolsarl 'uo!qez![e!:>ads [ea!2o[o!shqd .paddols pue paMoIs ?uaurdo[a~apq a y l q 3 1 r l ~a alje p a l a p 01 puc Bu!uaaaas l o j pasn aq p p o y s sale[@s! .s.uaJayrp lueay!ur;rs o u 'lsal a q l j o pua aq l '$v 11 uo pan'esse s e ?!~ .p oqlaur aql ,to s[!elap aqq ?no .luaurleaJ$ b[uo aq7 s n ~ y ~ olo s)ua~w!.r adxa ,E~nu!ur![aad Ja l jv 'uoqe[n"ou! Bn!paa,~ suu2swnap 'd .LO S u ~ p a a2j nq a q a q pa![dde .ral~t. syaam OM^ put? auo xayauru!p 7sa9~e1q a q l SBM sniYunj ay? .rar[?!a qn!qm ul squuldjo asor{? uerp 3u!.rllsnaur bq yJuttuJqap SQM suo!sa[ Yu!do[a~ap ,jo .raBuo[ dLaM slayuua aq l ' uo~ le [n~ouaz! ojaq pa.rJnaso 101 mai/nj pun ?loi121 102 Roots and Tubers The average lesion size induced in vivo by the Canker size lmm I , n VIVO ~ n o ~ u l o f ~ o n r- -- ---- - - isolates ranged f?om 5.8 to 7.5 mm (LSD = 0.9, P = ----I 0.06). Although there were significant differences between isolates, the lesions were small compared t o the cankers found under natural conditions. These results a re consistent, however, with previous reports on similar experiments and can be attributed to the difficulty of maintaining suitable environ- mental conditions for disease development through- out theexperiment and also to incomplete knowledge of the factors involved in symptom expression. The cultivar 30572, which had a n average lesion size of 7.1 mm, was significantly more susceptible than 30555 and 30001, which had 6.1- and 6.2-mm lesions. respectively (LSD = 0.3. P = 0.05). The younger plants were found t o be significantly less Figure 8. Scatter diagram of canker sizes induced by 20 susceptible, with average lesion sizes of 5.9 mm, than isolates of Colletotrichumgloeosporioides f. sp. manihotis in the older ones, which had 7-mm lesions (LSD = 0.8, vivo and in vitro, IlTA, 1982. P = 0.05). The average lesion size induced by the 20 isolates t ha t level there was no symptom expression. in vitro ranged from 4.8 t o 10.2 mm. Correlation Inoculum levels of 1 0 h r more are suitable in between the results of i n vitro and in viva screening screening for resistance. was low (r = 48, significant a t the 5% level) if all the Wilt and defoliation increased with inoculum 20 isolates are taken intoconsideration. If one isolate concentration in all varieties. The degree of wilt and that failed to induce canker in vivo is disregarded, defoliation depended on the level of resistance, the correlation coefficient is 0.67, significant a t the particularly in observations made from above the 14: level (Figure 8). point of inoculation (Figure 9). In observations made The conditions for successful i n vitro inoculation below the point of inoculation, there was no of cassava stems with C. gloeosporioides f. sp. significant difference between the varieties tested in manihotis have been defined, and preliminary wilt and defoliation. This may have been due to experiments have shown clonal differences in host interference by natural defoliation of lower leaves. response. This method s t i l l requi res f u r t h e r The overall effect of inoculation on wilt and standardization, and correlation between the results defoliation is shown in Table 6. Defoliation and wilt of in vivo and in vitro studies must be further above the point of inoculation and in the plant investigated. overall increased significantly with increases in Variability between pathogen isolates has been inoculum concentration. This finding suggests that confirmed. lsolates have also been collected from wilt and defoliation alone, particularly above the other parts of Nigeria (Onne and Umudike) and will point of inoculation, can be used in screening for be comparcd to Ibadan i s o l a t e s . B. Lame, J.P. resistance to CBB under controlled conditions.- Goffart, ?I lkotun and 1). Perrcaux S.K. Asiedu, E.R. Terry, R.L. Pelletier and U . Perreaux Inoculum Thresholds in Screening for Resistance to Bacteria1 Blight Virology In a host/pathogen interaction study, various popu-- A geminivirus, isolated from cassava plants with la t~onso f Xanthomonns campestris pv. manihotis mosaic disease by mechanical inoculat ion on were inoculated in three cassava varieties of differ- Nicotiana benthamiana, was purified from this test cnt CBB resistance levek, and disease development plant, yielding pure and concentrated virus prepara- was evaluated. Varieties TMS 30572, TMS 30001 and tions. Leaves of infected N. henthamiana showing the lsunikankiyan were stem puncture inoculated with characteristic symptoms of infection were harvested 72-hour-old pv, manihotis suspensions containing 15 days after inoculation. The tissue was homo- 108. 106, 1 0 4 and 102 cells per ml. Controls were genized in a 0.2 M phosphate buffer (pH 7.8) with inoculated with sterile distilled water. The inocu- EDTA and mercaptoethanol and clarified with chloro- lated plants were maintained in an air-conditioned form. After precipitation with ammonium sulfate and room a t a nighttime temperature of 25"C, daytime one centrifugation cycle, the virus was further temperature of 30°C and average humidity of 80'%, for purified by centrifuging twice on a 10 to 40% linear six weeks, after which disease development was sucrose gradient. evaluated. The experiment had a complete block Two rabbits were immunized by intramuscular design with two treatments replicated five times. injection of the virus preparations a t weekly The minimum inoculum level for the pv. manihotis intervals, followed by one intravenous injection. isolate used was found to he 104 cells per ml. Below Small quantities of antiserum were obtained with a Roots and Tuhe7.s 103 Percentage wilt and defoliation All attempts to transmit the geminivirus from T I N. benlhamiana to healthy cassava seedlings by mechanical inoculation, needle pricking or injection failed. After mechanical inoculation and injection of healthy cassava seedlings with a n extract from cassava plants showing mosaic symptoms, mosaic symptoms appeared on 1 out of 10 seedlings inoculated. Several attempts to purify the geminivirus from diseased cassava were unsuccessful, although the different fractions obtained during the purification showed infectivity when tested on N. henthamiana. In all attempts a fraction was obtained that had short, rod-shaped particles of various lengths, with a diameter of approximately 10 nm and a coarse suh- structure. This fraction showed maximum ahsorption a t a wavelength of 280 nm. These particles, which probably consist of protein, have heen reported to be present in diseased as well as in hea1t.h~c assava plants. In one purification attempt, using infected cassava materials, particles were also observed that ranged in length from 800 to 2,000 nm, had a diameter of approximately 18 nm, and were coarse in structure. I t could not he estahlished whether they consist of protein only or whether they occur in diseased plants only. J W.M. uan Lent Agronomy Effects of Age and Size of Stakes on lnoculum level (cell/ml) Tuberization and Initial Growth Figure 9. Relation between percent wilt and defoliation above the point of inoculation in cassava varieties and To study the effects of age and size of cuttings on different inoculum levels in Xanthomunas campestris pv. tuberization, stemcuttings were made from one-year- manihotis, IITA, 1982. old plants of TMS 30595. The cuttings were divided into three age classes corresponding to the basal, Table 6. Effect of different inoculum levels of intermediate and upper portions of t he plant. Xanthomonas campestris pv. manihotis on wilt Cuttings 10 cm, 20 cm, and 30 cm long, having two to and defoliation in cassava plants, IITA, 1982 three buds, four to five buds and six to eight buds, Percent wilt and defoliation respectively, were obt,ained from the cuttings of each Inoculation level, Above Below age class. The upper cuttings had a diameter of 0.8 to cells per rnl inoculation inoculation Overall 1.2 cm, the intermediate 1.5 to 2.5 cm, and the basal 2 loR. . . . . . . . . . . . . . . 43.0a* 21.3 a 35.9 a to 3 cm. Cuttings were singly planted a t an angle of 10" . . . . . . . . . . . . . . . 25.7 b 33.8 a 28.4 ab about 45" in 10 kg of topsoil in plastic pots. The experimental design was a complete randomized block with threereplications. Sampling was begun 10 Water (control) . . . . 1.4 c 23.0 a 10.6 c days after planting and continued a t 10-day intervals *Means followed by the same letter in a column are not for 90 days. Anatomical studies were carried out on significantly different a t the 1% level. Each value i s a mean of 75 thin root transections from each root to identify observations in each of two experiments. tuberous root initiation. The results show tha t stem cuttings taken from titer of 1/128 in agar gel diffusion tests with purified basal portions and having a length of 20 or 30 cm and virus (0.9% (wt/vol) agarose in 0.01 M. ammonium a diameter of 2 to 3 cm had a higher sprouting rate, molybdate, pH 7.8, with 0.001 M EDTA and 0.1%, number of stems per stand, number of tuberous roots, NaN3). The same results were obtained using a n tuberous root diameter, and shoot and root dry extract of N. benthamiana tissue infected with the weight. A similar trend was observed in plants from geminivirus; however, no reaction was seen when an intermediate cuttings 30 cm long and 1.5 to 2.5 cm in extract of cassava plants with mosaic disease was diameter (Table 7). The final sprouting rates were used. Presumably, this is due t o a very low con- 98.3%, a t 20 days after planting for intermediate centration of the isolated geminivirus i n cassava. cuttings 30 cm long, 99.4'y0 a t 19 days for basal 104 Roots and Tubers Table 7. Effect of age and size of cuttings on tuberization and initial erowth of cassava ~ l a n t sI.I 'rA. 1982 Tuber ini- Days to Final tiation, No. of Diameter Shoot dry Root dry final sprout days after No, of tuherous of tuberous weight, g weight, g Treatment sprouting ing, %, planting stems roots roots, mm per plant per plant Cuttings from upper portions: 10 cm long . . . . . . . . . . . . . . . . . . . . . . . . 27 84.3 70 1.0 1.9 3.9 60.2 5.9 20cm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 87.4 70 1.2 2.4 3.7 76.2 6.2 30cm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 92.2 60 1.8 2.7 3.8 87.3 7.2 Cuttings from intermediate portions: l0cmlong . . . . . . . . . . . . . . . . . . . . . . . . 26 94.7 60 1.0 2.3 4.5 96.4 8.9 20cm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 94.9 60 1.4 2.8 4.9 119.2 9.2 30cm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 98.3 40 2.4 4.1 8.4 134.7 11.7 Cuttings from hasal portions: l0cmlong . . . . . . . . . . . . . . . . . . . . . . . . 22 96.2 50 1.1 2.9 4.7 126.4 9.4 20cm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 9 99.4 40 2.4 4.8 9.2 160.2 14.6 30cm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 100.0 40 2.7 5.9 10.5 169.4 16.4 LSD (5%). . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 3.6 8.7 0.48 0.94 1.9 26.4 2.6 S.D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6 5.1 12.4 0.68 1.33 2.6 37.3 3.6 Note: Cuttings from uppir portions were 0.8 to 1.2 rm in diameter, those from the intermediate 2.0 to 2.5 cm, and those from the basal 2.5 to 3.0 cm. cuttings 20 cm long, and loo%, at 18 days for 30-cm (3) 16 hr , (4) 8/16 hr (plants were switched from 8-hr basal cuttings. daylength 35 days after planting to 16-hr daylength), The highest tuberous root number a t final harvest, and (5) 1618 hr (plants were switched from 16-hr 5.9 per plant, was achieved by 30-cm cuttings from daylength 35 days after planting to 8-hr daylength). hasal portions. The average tuberous root diameter Light exposure was extended by usc of fluorescent and shoot and root dry weights were also greater for lamps and shortened by rolling portable tables into a plants from 30-cm basal cuttings than from the dark room. others. The average root dry weight was 16.4 g per The varieties used were, 58308, TMS 30395, TMS plant, and the average tuherous root diameter was 30001, TMS 30572, TMS 50395 and Isunikankiyan. 10.5 mm. Cuttings from upper portions had reduced Thc first two varieties were regarded as early sprouting rates, numbers of tuberous roots, tuberous flowering, the second two as intermediate and the root diameters, and shoot and root dry weights. The last two as late flowering. They were planted on maximum sprouting rates, which ranged from 84.3 to 1 April 1980, and the experiment was terminated on 92.3%, were achieved between 26 and 27 days after 30 September 1980. Data on the effect of daylength planting. The average number of tuberous roots was upon the number of tuberous roots and the fresh and 1.9, 2.4 and 2.7 for upper cuttings having lengths of dry weights of the tuberous roots in those varieties 10 cm, 20 cm and 30 cm, respectively. The average are contained in Table 8. tuberous root diameter ranged from 3.7 to 3.9 mm. The early flowering varieties, 58308 and TMS Tuberization began earliest (40 days after plant- 30395, produced a significantly larger number of ing) i n plants from 20- and 30-cm basal cuttings and tuberous roots and higher tuberous root weights in plants from intermediate cuttings 30 cm long. But under the 8-hr daylength than under the natural tuberization was delayed in plants from upper and 16-hr daylength. However, the late flowering cuttings and did not begin until about 70 days after varieties, TMS 50395 and Isunikankiyan, produced planting in plants from 10- and 20-cm cuttings. I.N. more tuberous roots under the 8-hr and natural Kasele and S.K. Hahn daylength but the highest tuherous root weights under natural daylength. Effect of Daylength on Tuber Formation The numbcr of tuberous roots, and fresh and dry weights of tuberous roots produced by TMS 30001 Cassava is crown between latitudes 30°N and 30"s. andTMS 30572 were not sienificantlv different under Within that 'one daylength varies from about 10 hr, the 8-hr, 12-hr (natural). i6-hr , 8llk-hr and 1618-hr 13 min, to about 14 hr, 15 min. Cassava developed a t daylength treatments. It was concluded that these IITA (lat. 7" 25'N), where daylength ranges from two varieties are insensitive to daylength.-J.A. about 11 hr, 33 min, t o ahout 12 hr, 43 min, may Otoo and S.K. Hahn perform differently when grown a t higher latitudes. An experiment was set up to study the effects of daylength on tuberous routs, flowering and other Relation Between Agronomic Traits and Tuberous Root Yield plant characteristics. Five daylength treatments were used: (1) 8 hr (2) The rate a t which genetic improvement of cassava approximately 12 hr (natural daylength a t Ibadan), can be achievcd depends upon the associations Roots and T ~ l h f ~ r1s0 5 between tuberous root yield and other important Table 8. Effect of daylength on cassava tuber agronomic characters. A study of these associations formation, IITA, 1980 was carried out a t IITA, using six different popu- 14'resh Ilry lations with large genetic variation. Two of the No. of wt. of wt. of populations were planted in 1979, and the remaining tuberous tubcrous tuberous four were planted in 1980. A randomized complete Treatment roots roots, # roots. g block design with four replications was used. 58308 and TMS 30395 (early flowering) Observations were made on 21 trai ts : fresh 8 ~ hdra ylength. . . . . . . . . . 5.67 150.37 :i9.97 tuberous root yield, number of tuberous roots per 12-hr . . . . . . . . . . . . . . . . . . ?.8:3 47.76 14.88 plant, tuberous root size, dry matter and starch 16-hr . . . . . . . . . . . . . . . . . . 0.15 1.70 0.37 content in tuberous roots, total cyanide content in R/lG~h.r . . . . . . . . . . . . . . . . 2.00 67.96 19X:i both tuberous root and leaves, number of nodes to the 1618-hr. . . . . . . . . . . . . . . . . 4.83 8i .69 20. I5 branching point, branching height, number of days Lsn (5'j/,) . . . . . . . . . . . . . . 2.20 61.86 18.14 TMS 30001 and T M 3~057 2 (intermediate flowering) to flowering, plant height a t flowering, resistance to X~hrdaylength. . . . . . . . . . 4.83 191.28 4i.32 CML) and CBB, angles of first and second forking 12-hr . . . . . . . . . . . . . . . . . . 4.83 201.08 54.38 branches, stem girth, plant height a t harvest, canopy 16-hr . . . . . . . . . . . . . . . . . . 2.67 154.64 44.25 width, number of first forking branches, total number 8116-hr.. . . . . . . . . . . . . . . . 3.67 236.97 64.50 of branches per plant, and number of stems per stand. 1618-hr.. . . . . . . . . . . . . . . . 6.50 150.20 3 . 6 5 Two traits were considered as associated if they ISD (5%) . . . . . . . . . . . . . had significant correlations of the same sign in a t TMS 50395 and lsunikankiyan (late flowering) least four populations. Tuberous root yield had 8-hr daylength. . . . . . . . . . 3.33 110.20 24.98 significant and genotypic correlations with numher 12-hr . . . . . . . . . . . . . . . . . . 3.00 194.37 47.05 16-hr . . . . . . . . . . . . . . . . . . 0.67 37.88 8.48 of tuberous roots per plant, tuberous root size, stem 8116-hr. . . . . . . . . . . . . . . . . 2.00 46.94 9.42 girth, canopy width, total number of branches per 1618-hr. . . . . . . . . . . . . . . . . 3.67 85.29 18.30 plant, and plant height a t harvest (Table 9). It had a LSD (5%,) . . . . . . . . . . . . . . 1.93 84.54 20.39 negative correlation with number of days to flower- ing. The number of tuberous roots and tuberous root "Nn'si""fi'""t~ size were associated with the same traits as tuberous root yield. Total HCN in tuberous roots was associ- from each variety were processed to make several ated only with total HCN in leaves (r = 0.45, 0.44, products and 800-g samples of'l eaves were made into 0.50 and 0.51, significant a t the 1% level).-N.M. pondu, which is very popular as a leafy vegetable in Mahungu, H.R. Chheda and S.K. Hahn central Africa. Gnri was made through peeling, grating, fermenting for two days, dewatering and Quality Evaluation frying. Chikwange was made through fcrmenting. sieving, steaming, kneading and boiling of the pulp. Cassava contains hydrogen cyanide (HCN), usually Ntuka was made by fermenting and steaming the in the form of cyanogenic glucosides, which release pulp. Fufu (Zaire) was made through fermenting, sun HCN on hydrolysis. Consuming cassava that has not drying, milling and cooking. Attieke was made by been properly prepared can cause acute poisoning. A peeling, grating, mixing of the grated pulp with wide variety of traditional processing methods have previously fermented pulp a t a ratio of 3 t o 1; adding been developed in Africa mainly for eliminating oil and salt , and sun drying. Plakali was made in the HCN. A study was carried out t o determine the same way as attieke, except that oil and salt were not residual cyanide in the final products made from added. Oyoko was made by mixing the grated pulp tuberous roots and leaves. with fermented pulp a t a ratio of 3 t o 1, followed by Tuberous roots of cassava were harvested from steaming Pondu was made by blanching the fresh four IITA improved varieties, TMS 50395, 30572, young leaves in hot water (70%) for two to five 30555 and 30001, which vary widely in their HCN minutes, followed by pounding, dewatering and content. Five-kg samples of fresh tuberous roots cooking for one hour. The cyanide content of samples Table 9. Correlations between yield and agronomic traits in six cassava populations, IITA, 1979 t o 1981 r values fhr cassava populations Agronomic traits 1 2 3 4 5 6 No. of tubers per plant . . . . . . . . . . . . . . . . . . . . 0.86** 0.97** 0.91** 0.71** 0.94** 0.47** Tubersize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O.85** 0.83** 0.54** 0.68** 0.99** 0.48** Stem girth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.94** 0.35** 0.92** 0.67** 0.79** 0.44** Canopywidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.60** 0.46** 0.64** 0.57** 0.99** 0.55** Number of branches . . . . . . . . . . . . . . . . . . . . . . 0.79** 0.50** 0.79** 0.42** 0.74** 0.33** Plantheight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.60** -0.03 0.44** 0.49** 0.79** O.Si** Days to flowering. . . . . . . . . . . . . . . . . . . . . . . . . 0.30** 0.20* -0.39** -0.54** -0.33** -0.30** **Highly significant at the l'x, level. 'Significant at the 5% levcl. 106 Roots and Tubers of these products was determined by the automated total HCN was reduced by 96% and free HCN by 86%. enzymatic assay method. The results are summarized Pondu had about 96% less total and no free HCN. in Table 10. The general pattern that emerged in this study was In general, total HCN in the products was reduced that certain insufficiently processed products con- by 70 to 100%. But free HCN, although it was reduced tained a considerable quantity of HCN but that other in some products, was actually increased in others. well processed products, particularly those that have In cassava products that had undergone thorough been fermented, contain very little HCN that can be fermentation before being processed to make such detected chemically.-N.M. Mahungu, Y. Yamaguchi products as chikwange, fufu (Zaire) and ntuka, both and S.K. Hahn total and free HCN were almost totally eliminated. Total HCN was reduced by 83 to 96'j/, in such Yams products as gari, attieke, plakali and oyoko that had been peeled and grated before processing. Total HCN In IITA's yam improvement program. researchers are in gari was reduced by 83% to 98% whenit wasstored concentrating on the white yam (Dioscorea rotun- for four months under ambient conditions, and in data) and water yam (D. alata), the two most eba, a cooked form of gari, total HCN was reduced by important species. Their main aim is to find re- almost 100'%,. Free HCN was reduced to very low sistance against foliage diseases and the nematode levels in attieke, plakali and gari stored for four rot complex. The latter is a particularly serious months. However, the free HCN in fresh gari was threat to good quality and extended storability of increased by 98% and in oyoko by 5%, compared with tubers. Viruses are also a major problem with yams. that in fresh peeled tuberous roots. In fufu (Ghana), Since the crop is vegetatively propagated, both which was made through boiling followed by pound- problems are quite persistent and drastically reduce ing, total HCN was reduced by about 81% and free storability, field establishment and yields. HCN by 57%,. Merely boiling the tuberous roots of Considerable work was done this year on seed yam high HCN varieties did not reduce HCN sufficiently. technology and evaluation of breeding lines, several This processing method by itself should therefore be of which were tested at ITTA and in Cameroon in used only with low HCN varieties. cooperation with the Cameroon Root Crop Improve- In Nigeria fufu, which is made by soaking peeled ment Program. JITA seed yam technology is being whole, fresh tuberous roots in water for one day, well received a t the farm level and is proving to be followed by steaming and pounding, total HCN was highly economical. Efforts to further improve this reduced by about 96%, and free HCN by 46%. In technology arecontinuing. Much work remains to he konkonde, which is made by soaking fresh tuberous done on developing techniques to promote early, roots and then sun-drying, milling and cooking them, uniform establishment and to reduce labor. Table 10. Content of hydrogen cyanide (HCN) in traditional African cassava products made from IlTA improved varieties. 1982 Total HCN, mg\lOO g of fresh weighta Free HCN, mg/100 g of fresh weight" TMS TMS TMS TMS Percent TMS TMS TMS TMS Percent Product 50395 30572 30555 30001 Mean reductionb 50395 30572 30555 30001 Mean reductionb Peeled, fresh tuberous root. . 23.48 15.85 13.53 10.68 15.89 0.00 0.51 0.86 0.51 0.70 0.65 0.00 Attieke. . . . . . . . . . . . . . . . . . . 0.51 0.86 0.51 0.70 0.65 95.91 0.06 0.10 0.03 0.10 0.07 89.23 Boiledtuborousruot . . . . . . . 5.42 4.02 6.39 3.32 4.79 69.85 0.64 0.69 0.79 0.67 0.70 +7.69 Chikwange . . . . . . . . . . . . . . . . - - 100.00 C - - - 100.00 Eba (from 4-month-oldg ari) . - 0.02 0.04 0.02 99.87 - 0.01 0.01 0.01 98.46 Fufu(Ghana). . . . . . . . . . . . . . 4.37 2.96 2.7R 2.27 3.10 80.49 0.42 0.29 0.21 0.21 0.28 66.92 Fufu (Nigeria). . . . . . . . . . . . . 0.79 0.74 0.75 0.58 0.72 95.47 0.52 0.43 0.16 0.28 0.36 46.15 Fufu (Zaire). . . . . . . . . . . . . . . 0.04 - - 0.03 0.02 99.87 - - - - 100.00 Gari (freshly fried). . . . . . . . . 2.22 1.83 4.18 2.42 2.66 83.26 1.02 0.80 1.67 1.40 1.22 +R7.69 Gari (after 4 months storage) 0.30 0.32 0.32 0.21 0.29 98.17 0.30 0.30 0.21 0.23 0.26 60.00 Konkonde . . . . . . . . . . . . . . . . 0.71 0.78 0.78 0.60 0.72 95.47 0.27 0.05 - 0.05 0.09 86.15 Ntuka . . . . . . . . . . . . . . . . . . . . 0.05 0.02 0.04 0.01 0.03 99.81 0.05 0.02 0.04 0.01 0.03 95.38 Oyoko . . . . . . . . . . . . . . . . . . . . 1.11 1.48 1.98 1.28 1.46 90.81 0.51 0.58 0.94 0.68 0.68 +4.62 Plakali . . . . . . . . . . . . . . . . . . . 0.87 0.53 0.19 0.51 0.53 96.66 0.12 0.08 0.03 0.05 0.07 89.23 Fresh leaves. . . . . . . . . . . . . . , 305.00 155.00 142.50 - 201.00 0.00 8.24 3.35 2.95 - 4.85 0.00 Pondu (cooked leaves). . . . . . 10.63 6.82 8.15 - 8.53 95.76 - ~-~ - - - 100.00 ,'lnltial wripht of tuherous roots was 5 kg per replication per product. hReduction is expressed as a percentage of the totallfree HCN in peeled, fresh roots and fresh leaves 'XI) HCN detected (less than 0.01 mg/100 g of fresh wright). Roots ~ n r7l ' uh~rs 107 Genetic Improvement Tahle 11. Performance of white yams in uniform and advanced yield trials. IITA. 1982 Yield Trials Percentage yield. uf tubers 1)anlage scores" Several lines of D . rotundata and D . alata wcre clone t/ha markctable Ncrnatodc Virus evaluated in a staked uniform yield trial and an Uniform trial advanced yield trial a t IlTA . In the uniform trial. ~ b. .i. . . . . . . . . . . . 41.5 8.4~ .9 .'1 .0 1.6 there were 10 lines of D . rotundata and 6 of D . alata . R~7.21.248. . . . . . . . 29.8 46.0 3.3 2.0 The advanced trial had 13 of the former and 11 of the Nwnuoko (check) . . 21.8 65.5 4.3 3.3 latter. The trials were in a randomized complete TDr 148 . . . . . . . . . . . 21.1 block. with three replications for D . rotundata and TDrS.4002.CZ26. . 20.6 four for D . alata . Plants wcre spaced 1 m x 1 m in TDI. 820 . . . . . . . . . . . 17.6 single 11-m rows in the advanced trial and in double TUr 819 . . . . . . . . . . . 11.1 11-m rows in the uniform trial . The 1). rotundata R17~167-531. . . . . . . . 16.8 plants were subjectively evaluated for virus damage Boki . . . . . . . . . . . . . . 12.0 and the tubers for nematode damage. and D . alata W512 . . . . . . . . . . . . . 8.8 plants were rated on scorch damage . For yicld Mean . . . . . . . . . . . . . 20.7 evaluations only the inner 10 plants were weighed at LSD (5'jb) . . . . . . . . . 9.2 harvest eight months after planting . The consistency S.E . . . . . . . . . . . . . . . t 3 . 1 index was used to measure inconsistency resulting Advanced trial from changes in the ordering of the genotypes from RM7.4.198 . . . . . . . . . 41.8 one year to the next . RM7.3.168 . . . . . . . . . 37.7 The performance of D . rotundata in these trials is ltM7.4.177 . . . . . . . . . 36.3 given in Table 11. The clone Abi gave the best yield Gbangu . . . . . . . . . . . 28.4 and percentage of tubers marketable . Only one R18-370~790. . . . . . . . 27.6 R18~177-I2. . . . . . . . . 22.4 77.1 4.6 3.7 hybrid line. RM7.21-248. gave a better yield than the Nwapoko (chcck) . . 21.5 78.1 4.6 3.0 Nwapoko check clone . In the advanced trial. the highest yielding clone was 12M7-4.198, with 41.8 t/ha and 95'%, marketable tubers. It also had a low virus damage score . RM7-3.168 had the lowest nematode ltB6-114-1049 . . . . . . 15.1 69.0 5.0 3.7 damage score. Most lines had high scores for TDr830 . . . . . . . . . . . 12.8 97.4 5.3 3 3 nematodedamage. whichis stilla major cause of poor Ausuku . . . . . . . . . . . 11.9 97.8 5.0 3.0 storage . Mean . . . . . . . . . . . . . 2.1.4 X0.9 4.4 3.9 The performance of D . alata is given in Tables 12 LSD (.5 ".L- ). . . . . . . . . . 14.3 32.9 1.1 1.4 and 13. Thirty percent of the variation in the S.E. . . . . . . . . . . . . . . &4.8 11.3 0.4 0.5 performance of clones was attributable to clone x "I)amitg~w as evaluated subjectiri.ly on n 1 1.0 5 scale, whcrr. 1 = year interaction and 25'%, to the clones . Both types no visiblc symptoms and 6 = severe symptoms. were significant. TDa 251 gave the highest mcan yield for three years . TDa 310, 5 and 204 were fairly consistent in their performance over the years; TDa TDa 291 and TDa 297 showed the highest level of 297 was least consistent . resistance to scorch . Although genotypes showed much variability in yield from year to year. such was not the case with Seed Yam Production the scorch score. which remained relatively stable Two D . rotundata cultivars were evaluated for their over the years for each genotype . The difference in efficiencyi n producing seed yams . Cut pieces of 100 to genotypes accounted for over 70% of the variation . 150 g were treated with ash and allowed to dry Table 12 . Performance of water yam clones in uniform vield trials. lITA Yleld. t/ha Scorch score" Consistency Clone 1980 1981 1982 Mcan 1980 1981 1982 Mean index TDa 251 . . . . . . . . . . . . . . . 49.7 25.2 30.3 35.1 2.7 4.2 3.1 .3 .. i 1.2 TDa 204 . . . . . . . . . . . . . . . . . . 37.4 29.9 26.7 31.3 3.2 4.0 3.2 3.4 0.6 TDa 5 . . . . . . . . . . . . . . . . . . . 3 1 1 24.5 26.4 27.3 2.8 4.1 3.2 3.3 0.6 TDa 297 . . . . . . . . . . . . . . . . . . 14.8 30.2 29.1 24.7 1.5 1.5 1.9 1.6 2.6 TDa310. . . . . . . . . . . . . . . . . . 25.5 18.6 22.3 22.2 2.6 2.6 2.8 2.7 0.6 TDa 291 . . . . . . . . . . . . . . . . . . 26.5 16.1 23.1 21.8 1.4 1.6 1.6 1.5 1.0 Mean . . . . . . . . . . . . . . . . . . . . 30.8 24.1 26.3 27.1 2.34 2.99 2.61 2.66 LSD (5%) . . . . . . . . . . . . . . . . 9.6 12.6 4.6 9.8 0.49 0.50 0.52 0.57 S.E. . . . . . . . . . . . . . . . . . . . . . 3.2 4.2 1.5 4.4 0.16 0.16 0.17 0.25 "Scorchdarnage was evaluatrd subjectively on a 1 to 5 scale. where 1 = 0 to 20Y0 symptoms and 5 = srvere symptoms. 108 Roots and Tubers Table 13. Performance of water yam clones in The yield from herbicide treated plot,s was higher advanced yield trials, IITA, 1982 than that in hand weeded plots (Table 14). The yield Yield. Scorch of Nwapoko with herbicide and no staking was Clone t/ha score" lowest. This cultivar is less vigorous and grows TDa309 . . . . . . . . . . . . . . . . . . . . . . . . . . . 34.3 3.7 slower than Abi, which was able t o establish a TDa316 . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.7 3.4 canopy after one weeding. Since Nwapoko still TDa67 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.4 4.3 lacked a good canopy a t that time, weeds were able to Tlla167 . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.4 4.7 compete with i t successfully. In addition to its early TDa 308 . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.4 4.5 establishment, Abi also has resistance t o virus and Tna31i . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.0 4 .1 other field diseases. TUa200 . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.8 3.6 Modified staking allowed plants to form a canopy, TDa 302 . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.8 2.9 which subsequently suppressed weeds. The PVC T,.D a 314 . . . . . . . . . . . . . . . . . . . . . . . . . . . l i .1 2.9 1 Da 300 . . . . . . . . . . . . . . . . . . . . . . . . . . . pipes and plastic mesh proved to be good material for 16.5 4.6 TUa 199 . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.0 4.8 staking. Since they are not damaged by termites, they can be reused for several years. The bamboo stakes Mcarr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.0 3.9 r were readily infested with termites before harvest. 5 . . . . . . . . . . . . . . . . . . . . . . . . . . 18.6 0.9 The plastic mulch gave good weed control S.E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.8 0.3 throughout the growth cycle of the yams and had no "Scorch damage was evaluated subjectively un a 1 to 5 scale, adversc effects on the plants. Measurements of soil where 1 = Ot o 20'$& symptoms and 5 = sevrrr symptoms. temperature showed that harc soil had the highest average afternoon tcmperature (40.7% + 5.3'). before planting. The planting sites were plowed and Under bare plastic mulch the soil temperature was ridged by conventional methods (with ridges 1 m 36.Z°C + 2.1'. With plastic mulch and a yam canopy, apart). and thc setts were planted 50 cm a pa rt ~ n r o w s , the soil had an average afternoon temperature of with 240 setts per plot in three replications. One 33'C. The profile of the difference in temperature treatment was traditional tield cultural practices bet,ween morning and afternoon is shown in Figure without herbicide. Thc second treatment was a 10. modified staking system that consisted of arched, Once the soil moisture in plots without mulch had half-inch PVC pipes supporting 4-in plastic mesh been reduced, the plants shed their leaves, and and included the use of herbicide. The herbicide, afternoon soil temperatures increased. Some plants a mixture of Cotoran and Dual, was applied pre- wit,h plastic mulch still had green leaves a t harvest. emergence at thera te of 2 kg a.i/haimmediately after The mean soil moisture content under plastic mulch planting. The third. treatment also included herbicide one weck before harvest was 6.7%, which was application but no staking. Black and white poly- significantly different (at t he I % , level) from the ethylene plastic mulch was placed on one plot after moisture content of unmulchcd soils (2')(,). Plastic germination. mulch had no adverse effect on the tuhers. Termites, r1 1 h e soil temperat,ure and moisture were monitored mealybugs and nematodes were present in negligible in the plots toward the end of the rainy season until quantities in all plots. The root-lesion nematode, harvest. Temperature was measured with soil Pratylenchus sefaensis. was found under plastic thermometers placed 5 cm deep on the crest of the mulch and could he a problem in the long run if a ridges in plots of one replicate. Readings were taken proper rotation is not used. at 0900 and 1400 hc~urs.S oil moisture samples were Although yield differences were marginal (except taken from four locations in each of the mulched and in the case of Nwapoko with herbicide and no unmulched plots. Soil moisture was expressed as a staking), the monetary value of the labor saved and of percentage on an oven dry basis. Soil samples were t,hc increased yield were :ippreciable. Technology for also t.aken a t harvest to determine the nematode efficient production of healthy seed yams is hcing population. further evaluated. The use of healthy, clean seed yam tubers results in early, uniform establishment and Table 14. Effect of improved and traditional cultural gives high yields. practices on seed yam yield, IITA, 1982 True seeds of several U . rotur~datafa milies, which Y- ie~l-d . had been direct seeded or transplanted to well- Treatment t / ha prepared seedbeds, produced seed-yam size tubers iZhi ranging in weight from 100 to 1,200 g and yielded up Herbicidr + modified staking. . . . . . . . . . . . . . . . . . . 14 to two and a half times more than the traditional Herhicidc + no staking7.. . . . . . . . . . . . . . . . . . . . . . . I6 system (Table 15). In addition to producing tubers of Tradit.ional p ~ r : t . i c e s . .. . . . . . . . . . . . . . . . . . . . . . . . 10 uniformsize, these families alsnrcsponded positively Nwapokn to denser plantings. 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( d 1 3 8 ~ 3~)1 e x 8 o ~ d 8.1 9'0 Z6'0 991 ' ' ' ' @qlL luauraholdur~ s d o q qoo>~[ e u o q e ~u oozame3 aush lad sam? ma$s lad .qlmo~2 .q?~oxZ aunt3 aq3 u! uo!lua$le qsnm ah!asaa 01 panuquos aund luals anhzal ,jo urals J""1 ( 3 8 x 8 3 ) xalduro3 q - 0 - 0 U Iek~aoa aqL 10 'ou ueam 'nu ueam anqa1a)l ah!le[aa 2861 'VLII 'asnoquaa~3sa yl us sauq o+e+odl aaMs luels!saJ [!AaaMjo q ~ ~ o . 1uo3 u o!?e[ndod I!AaaM qS!q pue ?q3noapjo 13a~33'L I a [ q e ~ u y n '~X ' S pun za.fvnlv ' N ' ~ - ' ( L Ia [ q e ~m) als ad ol f: ruoq paYu1?.1'.8u!u!o?s Xq pau!urxa?ap 'uallod pooa aeAJeI 3saMaS aq? 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S U ~ ~ , , . -Ij\rrZ'xp m : ~ U U O'a : U M ~ O W,a : S U ~ ' R: ~ J I I'V ma* suoj,jerol lsa? aq,1, : a ~ o ~ 9'0 1'0 0 P O P O P 0 9'0 2'0 1'0 9 0 F O F ' O L ' Z t'l 1'1 I 0'ZU'ZT 7 ' s Z I EO ' 1 Z't 1 1 I I 9'0 PO PI 6'0 8 0 9 9 8 s 1's VP fi'9 2'8 (%) US7 6 0 1'0 L Z I L O L O P'O 910 LOO 6 0 P O P'O I I L 6'01 6'P S'C L'GZ ueom 6XO 8'1 0'0 ?C X F RL 8'0 8.0 KO 0'0 1 0'1 F'I 8'9 X'S CF b1 6'1 Eli1 JP-clT.1. LL'Z Z I TO CZ CZ YO YO E'0 0'0 C0 0.1 0 0 fro P X CP 8 ' t I L'l ?'Z 9'1Z 99Z8 Sl.1, P i l Z I 0'0 X'Z O'C 0 ' 00 '0 Z'O 0 0 0'0 S'O F ' 0 0 0 Z'6 0 ' L 6 L 61 SZR'9Z 66C0LS.T-.- 1 . 88'7, 6.0 KO O't; 0'0 O't C O F'O 8'0 0 0 0'0 C.OE.0 9'6 U'P 8'6 E'C 6'LZ'ZZ 60S8S1,l ZC'I 0'1 0'0 OE 5.0 0 0 SL $ 0 0'0 0'0 1 0.0 S'O ROI 1'8 8'6 1'9 Z'Z 9.62. PZSR SIL OL'Z R I 0 0 O Z 0'1 C'E8Z V'O (1'0 CO S I K O 0 0 OIL 2'8 S'PT 6 P C'O6'9Z LPPUSlJ, PKZ C O 0 0 0'0 0 0'0X'O 0 SO 0 0 0'1 X ' O C ' O X'II F'8 0'21 001 XFBLZ LCFOLSTL r i P L ?'O (I'O 0 1 0 1 0-0 9-0 0'0 0'0 0.0 8-0 F-0 0-0 6-ZI L6 8'6 L P'S 9'6Z IOPR SlL Z 6 1 PO 0 0 O'Z 0'0 0 ' 00 '0 0 0 0 0 0 8'0 0 ' 00 '1 6'21 C'L 6'01 8.2. 9'EZ'SP 386PZS1,L 8Z.Z P'O 0'0 8.1 0 0 5.0 11.0 6 0 0'0 E'O 0'1 0 1 0'0 ?'LI XL 96 I El: LFG W Z 6 STT. 112 Roots and Tubers Tablc 18. Performance of selected cocoyam lines. The leaf wat,er potential of' both cul t ivars IITA, 1982 decreased rapidly in the daytime, and the minima Yield. Harvest No. of' Leal area were observed around 1515 hours (Figure 12). Leaf line t/ha index leaves per plant, m' water potential was lower for both TCe 23 and TCe 36 XI-9-281. . . . . . . . 9.6 0.44 4 0.51 in the WTI5t reatment. I t increased for both cultivars in the WT5" treatment. The TCe 23 control plants hehaved like those under WTjo and the TCe 36 plants TXS 23 . . . . . . . . . R.5 0.' 36 4 like those in WT15. When leaf water potential was at X19-9-2x7 . . . . . . . 8.2 0.19 5 its minimum(l515 hours), leavesdid not wilt in any of the treatments. Recovery of leaf water potential began toward the evening. ?I 1h e evapotranspiration rate of the cocoyams TXS 18 . . . . . . . . . 4.1 0.28 .4 0.42 (EVT) varied according to the open pan evaporation (E,) and the depth of water tahle (WT) according to Mean . . . . . . . . . . 7.6 0.29 4 3 0.63 the equation. ET = 0.50 + 0.76 E, - 0.01 WT (R = LSD (5%). . . 3.0 0.13 0.5 0.32 0.92 and K" = 0.85). where ET and E, are weekly means in centimeters per day and WT is in centimeters. 8'j;,. On account of low fertility, the pollen grains did The average evapot,ranspiration rate for the period not dehisce naturally. The lack of seed set from of measurement (89 days) was 0.77,0.52, 0.34 and 0.17 crosses between cultivated Xanthosoma and thc cm/day in t h e WTI5, WT3", WTS0 and WT7" yellow hiotypc could be the result of the poor fertility treatments, respectively. The average potential of the yellow type, which may he further aggravated evaporation rate for the same period was 0.51 cm/day, by incompatibility harricrs. M . N . A luarez and S.K. The plant height of TCe 23 and TCe 36 decreased Hah,n significantly with increasing water table depth (Tahle 19). This decrease was accompanied by a Agronomy statistically insignificant trend toward smaller leaf area. Cocoyams, Colocasia csculenla (L.) Schott, are grown 4 s shown in Tahle 19, fresh corm yields of TCe 23 throughout the tropics and suhtropics. Since the were significantly higher (334.1 giplant) under WT16 rainfal l i n these regions is not always well than WT7(, (152.2 g/plant), whereas the response of distributed throughout the year, the crop often TCe 36 to a higher watcr tahle was insignificant. As experiences plant water deficits. To gather infor- expected, total water use decreased as the water mation on the response of cocoyams to soil moisture tahle was lowered, and water use efficiency (grams conditions, a study was carried out in which the of corm produced per liter of watcr expended) water tahle was maintained a t different depths in a soil profilc. The experiment was conducted during the dry season of 1981 82 in field lysimcters packed with surface sandy loam soil (Apomu series) a t a hulk density of 1.4 g/cmi'. Two suckers, one each of two cot:oyam cultivars (TCe 23 and TCe 361, were planted in each lysimeter. The plants were uniformly fertilized with N, P and K fertilizers. Four weeks after planting, five treatments were imposed: (1) WT15, in which the water table was maintained a t a depth of 15 cm, (2) WTRo,( 3) WTSo,( 4) WT7" and (5) WT,,, in which no water tahle was Leof water potentlo1 I borr l present. Treatment 5 was the control; i t was irrigated 6 . on alternate days with an amount of water equal to the mean pan evaporation during the dry season (4.5 mmlday). Treatments were replicated three times in a randomized block design. Stomata1 resistance and leaf water potential were measured periodically. Figurc 11 indicates that the stomatal diffusion resistance of the cultivars went through nearly identical daily cycles. There was an early morning low and a gradual huildup till sunset and a rapid rise Hour of the day after dark, resulting from the usual stomatal closure. Figure 11. Diurnal changes in stomatal resistance and leaf The depth of the water tables made no apparent water potential of two cocoyam cultivars for different difcrence in stomatal diff'usionr esistance. water table depths, Il'rA. 1982. Roots and Tubers 113 Table 19. Effect of water table depth on cocoyams, IITA, 1982 Average plant Frcsh corm height, cm yield, g/plant Watcr Watcr use Water tahle depth TCe 23 TCe 36 TCe 23 TCe 36 use, 1 cfir:iencv, yil 15cm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48.2a* 57.8 a 334 a 246 a 182 3.2 30cm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 9.0a 45.8 ah 265 ah 187 a 122 .'3.7 50cm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35.Xh 35.8 hc 21 1 ab 161 :I 81 ,1.6 70rm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.7h 26.0 c 15" b 118 a 39 6.9 No water tahle . . . . . . . . . . . . . . . . . . . . . . . . . 49.7 a 55.2 ab 333 a 180 a LSD (SC%,). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1 19.1 173 169 *Averagrs followrrl by the samc letter do not d i f i r at the 5% level of signilirance. increased. The yield model indicates that corm yield qualify fur plant quarantine certitication and be was related exponentially to water tahle depth with moved through international quarantine barriers. a negative exponent. Fresh corm yield increased The unit also multiplies improved varict,ies and linearly with increases in lcaf area (Y (glplant) = preserves vegetative germplasm. 55.5 + 0.10 LA). From these data i t is clear that a high water table Cassava of 0 to 15 cm or very regular resupply of moisture, as in the control treatment, is essential for maximum During 1982 thc major focus of tissue culture work on growth and corm production of cocoyams. The cassava was meristem culture for elimination of varieties differed very little in their responses to diseascs and international distrihution of material. lower water tables, although leaf size and changes in Six varieties with resistance to the cassava mealv" hue.~ , daily leaf water potential showed some relation to and green spider mite were successfully regenerated water table. B.S. Ghun~anan d R. La1 by the meristem culture method in combination with thermotherapy, as descrihcd in the IITA Annual Nematology Report for 1979. Four cassava varieties that were ree., enerated fi-om meristem culture in 1981 werc Root-knot nematodes are common throughout the indexed and then certified by plant quarantine tropics and subtropics and a r e becoming a n authorities a t Ibadan in 1982. These varieties carry increasingly serious threat to good crop growth as sources of resistance to the mealybug and green the land is farmed more intensively. An integral part spider mite and are low in cyanide content. Thcse and of IITA's root crops improvement program is to the eight varieties previously certified are now screen its germplasm collection systematically for available for distrihution. resistance to nematodes. A total of 55 sweet potato A total of 26 consignments of disease free cassava lines have shown good resistance in greenhouse in tissue culture form werc delivered to 19 countries, retesting to the root-knot nematodes MeLoidog,yne 18 of them in Africa (Figure 13). The handling of incognita race 2 and M. jauanica. The resistant lines tissue culture material upon arrival in recipipnt will be further tested under field conditions. countries has improved as a result of a root crop In greenhouse testing of white yam (D. rotundata) tissue culturc training course that took place latc in germplasm, the cultivar Abi showed only light root- 1981. Reports from the recipient countries indicate knot galling on the tubers from both M. incognita t h a t t he materials received are ei ther being race 2 and M. jauanica. Juve~li leosf M. jauanica were multiplied or a re still being evalwated. recovered from the soil hut not for M. incognita. Thc reniform nematode, Rotylenchulus reniformis, and Sweet Potatoes the root-lesion nematode, Pratylenchus sefaensis, reproduced only to a limited extcnt on Ahi. Therc In its work on sweet potatoes, thc tissue culture unit were no symptoms of nematode attack or repro- concentrated this year on meristem culture for duction on thc other seven yam lines tested. The eradication of diseases, germplasm conservation and spiral nematode, Helicotylenchw pseudorobustus, international distrihution of tissue culture ma- did not reproduce or survive on any of the yam terials. Seventeen sweet potato varieties were lines. Carryover infections of the yam nematode, successfully regenerated by means of meristem Scutellonen~ah rad.ys, were recovered from tuhers in culture, as described in the IITA Annual Report fnr five of the eight yam lines tested.-F.E. Caueness 1979. Eight varieties were indexed, tested and then certified by the plant quarantine authorities at Tissue Culture Ibadan for exportation. In virus indexing of the meristem culture material, The principal objective of the t ~ s s uceu lture unit is to a test involving grafting to an indicator plant, render imuroved varieties of cassava. vams and sweet Ipomoea setosa was used along with Serological potatoes insect pest and disease free, so tha t they can Specific Electron Microscopy (SSEM). Two disease 116 Roots urld Tubers Production of Polyploids Table 21. Chromosome numbers of various sweet potato species Since polyploids are usuallj- better yielders than diploids and since there can he differenccs in the Species Chromnsome response of different cultivars to polyploidy, fc~ur no. Species numher promising clones of cassava, TMS 30001,30555,30572 1 Ipomoea lacunosa . . . . . . . . . . . . . . . . . . . . . . 30 and 50395. were selected t o induce tetraploidy. 2 lpornora trifida . . . . . . . . . . . . . . . . . . . . . . . . 30; 60 Tetraploids are heing produced to make triploids, 3 Ipomoea tiliacea . . . . . . . . . . . . . . . . . . . . . . . 60 which are reported t o he superior in many crop plants 4 Ipornoea littoralis. . . . . . . . . . . . . . . . . . . . . . 60 5 Tetrapluid sweet potatoes to the diploids or tetraploids, especially when the (five accessions) . . . . . . . . . . . . . . . . . . . . . 60 economically important yield componcnt is not the 6 Seeds from the cross, sweet seed. Once superior tetraploids and triploids are potatoes x K-221 . . . . . . . . . . . . . . . . . . . . 60 isolated, they can be perpetuated without major 7 Ipomora hatatas (sweet potatoes). . . . . . . . . 90 difficulties since cassava is a vegetatively pro- pagated crop. Sprouting axillary buds are treated with O.5'%, species can he useful i n t he improvement of aqueous colchicine solution for 24 to 48 hours and agronomically important characters such as disease then covered with cotton wool. The buds and cotton and insect resistance. Because of the i r high wool are kcpt moist with colchicine solution. T.ater, pot.ential, a few species were collccted and their the treated buds are washed thoroughly with water. ploidy status determined (Table 21). Now they are The tetraploids can he identified by their leaf shape, being used to produce interspecific sweet potato thickness and color. Their ploidy status will he hybrids. Two accessions of tctraploid sweet potatoes confirmed when they flower. produce 10 to 20% dyads. These plants also produce "giant pollcn" (see phot~lgraph)A. n average of 10 to Anther culture 15% of such pollen grains was observed, although Haploid plants a re valuable in genetic, cytological their frequency varies from flower t o flower. and breeding research. S ince they a r c in a hemizygous state. when their chromosomes aye Cocoyams douhled, eit,her naturally or by colchicine treatment, a h ~ l m o z y g ~ ~diupslo id results. Thus. hon~ozygosity The two most important cocoyams are Colocasia can he achieved in one generation, whereas with csculenta and Xanthosoma spp. Genetic variability in conventional breeding techniques i t takes five or six this crop is limited hecause both male and female generations. The study of meiosis in haploids has sterility are prevalent. .4lthough there are many contributed somewhat to tentative theories ahout causes of this sterility, i t is attrihuted mainly to hasic chromosome numbers in many genera. One different cytogenetical phenomena such as poly- met,llod of producing haploids is by anther culture. ploidy, structural hybridity, desynapsis and ahnormal Some plant species produce plantlets directly from tapetal development. Cytological screening of the clones and identification of polyploids will enable us tlie microspores, while others produce a callus first,, to plan appropriate breeding strategies for these which is then trzinst'errcd to a differentiation medium vegrtatively propagated species. I t should also for rcgenerat.ing plants. reveal the causes of sterility and provide an Anther culture was begun a t IITA this year t o opportunity for assessing the effect of polyploidy on produce haploids in cassava. Flower buds containing tuber yield. pollen grains a t the uninucleate stage were collected Cyt.~)logicals creening of clones of C. esculenta and stored a t 8'C for a minimum of three days hefore revealed that accessions TCc-23 and TCe~36( see being cultured. The culture media used were M and S photograph) are triploids (2n = 3x = 42). The high basic media with 2,4-dichorophenoxy acetic acid sterility of these clones <:an be attrihuted to meiotic (2.4-U) (10P2"'), sucrosr (30 gm/l), agar (8 gm/l) and irregularities such as high trivalent frequency (7 to kinetin (10-'I"). Thcy were adjusted t o pH 5.8 before 10 per PMC), irregular separation of chromosomes at steri1iz;rtion. The cultures were kept a t 25O to 26OC A - l and presence of laggards. The clone TCe-23 was and exposed to light with a n intensity of 3,000 lux for found to exhibit desynapsis. Both the triploid clones 12 hours a day. Callus formation was ohserved three are superior yielders. weeks after culturing the mthers . The calluses are In Xanthosoma sp. collections, the yellow cocoyam heing multiplied for later transfer to a differentiation TXS-11 was found to he a tetraploid (2n = 4x = 52). medium. The clones TXS-17, TXS-23, TXS-42b and TXS-427 are diploids with 26 somatic chromosomes. At, diakinesis Sweet Potatoes and M-I (see photograph), 13 hivalents were ohserved in PMCs. K . V . Bai Swcet potatoes (Ipomoea batatus) are hexaploid, having 2n = fix = 90 chromosomes. The majority of thc species in the gcnus arc diplr~ids(2 x = 30) and a fcw are tetvaploids (2n = I x = 60). Some of these Farming S y s t ~ m s 119 IN I ~ E C E N TY E ~ tShe multidisciplinary research of development experts, and governmcnt workers to IITA's Farming Systems Program has been evaluate experiences with clearing and developing dedicated to improving or finding a substitute for tropical forest areas over the last decade. It also led the traditional bush fallow agricultural system. to the formation of the International Committee on Although this system is in balance with the ecology Land Clearing and Development (ICLCD), which was and prevents permanent destruction of land re- charged with publicizing the views and concerns sources, it is inefficient and low in productivity. adopted by the symposium and with forming a Using this system, farmers cannot keep pace with coordinating body for the improvement of land population growth and increasing demand for food. clearing and development in the tropics. Research projects tha t address this central Three important special projects made their concern continue to he the mainstay of IITA's influence felt for the first time in 1982. The nitrogen Farming Systems Program. This work is now being utilization project being carried out with the complemented, though, by a major research effort Institute for Soil Fertility in the Netherlands generally referred to as on-farm adaptive research. In established two large experiments at Onne in the this research methodologies are being developed for high rainfall region of Nigeria and yielded valuable identifying on-farm production constraints and for information in its first year. A joint research pro- designing and implementing adaptive research ject with the International Fertilizer Development programs in which technology from IITA and other Centre in the United States was also successful in its sources will be tested in cooperation with farmers first year of fundamental studies on nitrogen and and development workers. This work, now being phosphorus uptake from soils in the humid and carried out in Nigeria, Ivory Coast and Cameroon on subhumid tropics. a preliminary basis, involves a sizeable portion of the Finally, in the first phase of the hydromorphic or program's scientists not only in field research, hut wetlands project,, executed jointly with the Institute also in the meetings and training events related to for Land Reclamation and Improvement in the this regional effort. Netherlands, it was discovered that the total avail- This new concern led during 1982 to two crucial able wetland arca in West Africa is much greater and highly successful meetings a t IITA. The first than est,imated in recent development studies. It thus brought together about 40 scientists from all over the seems quite realistic that the development of these world to discuss their experience in various aspects wetlands, which in general are considerably more of on-farm farming systems research from both the productive than the more typical soils of the region, socioeconomic and agronomic viewpoints. The could contribute substantially to increasing food symposium resulted in a valuable exchange of ideas production in the sub-Sahelian region. and data, and a consensus was reached about the In 1982 the Farming Systems Program placed essential features of this research and about the greater emphasis on appropriate equipment, mulch great value it could have in the creation of adapted production and management, and socioeconomic and acceptable technologies for the small farmers of studies and laid the foundation for a new, major the developing world. multidisciplinary effort to study constraints in large The second workshop was sponsored jointly by scale crop production. The West Bank catchment is IITA, the International Crops Research Institute being used for this purpose. It was clear from the 1981 for the Semi-Arid Tropics (ICRISAT), Institut de and 1982 dat,a from the West Bank experiment that Kecherches Agronomiques Tropical (IRAT) and the tillage versus no-tillage treatments completely Deutsche Gesellschaft fiir Technische Zusammen- overshadowed the residual effects of the original arbeit (GTZ). Its aim was to bring together farming forest clearing methods. This pioncering trial was systems researchers from all over West Africa to therefore abandoned and transformed for the 1983 exchange ideas and create a farming systems crop season. research network for the region. This independent The IITA rotary injection planter was successfully organization has now been established and promises adapted for medium scale operations with low to be a valuable asset to scientific exchange in West horsepower tractors and is probably a t a stage now Africa. where any further development must he left to other Another important event for IITA's Farming initiatives. Utilization of this equipment in medium Systems Program this year was the first Inter- to large scale operations has shown that the next national Symposium on Land Clearing and Develop- requirement for expansion by small farmers is rapid ment, which was held and organized by IITA with and timely harvesting, which will receive high assistance from the United Nations Development priority in IITA's agricultural engineering section Programme (UNDP), U.S. Agency for International for the next few years. Development (USAID) and Swedish Agency for In research on plantains and cooking bananas, Research Cooperation (SAREC). The meeting good progress is being made in production agronomy. brought together about a hundred scientists, But the threat of invasion by the black sigatoka 120 Farming Systems fungus in West Africa(it has already been reported in Nigeria. Soil profiles representative ofthe land forms Gabon and Cameroon) may require that we change were described and sampled for laboratory analysis our priorities in research on this very important food and evaluation. Present land use a t each study site crop. Meetings have been held with scientists from was also described. Three types of wetlands have the Caribbean area and with interested donors t o been identified in this region: (1) the small inland discuss a worldwide program for improving these valleys, termed fadamas (5 to 40 ha), in the savanna spccies with special emphasis on development and region of central Nigeria (near Bida), with pre- introduction of materials with resistance to the black dominantly coarse textured soils derived from sigatoka fungus. The threat of this disease has also Cretaceous sandstones; (2) the extensive Anambra led to the introduction of meristem culture tech- River Hood plains and terraces near Adani in nology a t IITA and a training program to create a southeastern Nigeria, with medium t o fine textured network of competent scientists who can participat,e soils derived from Tertiary shales; and (3) the small in an Africa-wide network for development of to medium sized inland valleys or swamps (20 to 100 plantains and cooking bananas. ha) near Bende in the humid region of southeastern Nigeria, with fine textured soils derived from Soil Management and Tertiary shales. Land Development Soil Characteristics Wetlands Characterization and Soil depth and t,exture, chemical properties and Evaluation nutrient status, clay mineralogy, water holding characteristics, depth and seasonal variation of The increasing demand for rice as a staple food in groundwater tahlr, flooding hzrzards, and toxicities tropical Africa during the past decade necessitates (Fe, for example) are being analyzed and evaluated. more intensive utilization of suitahle wetlands Some properties of selected pedons are given in (inland valley swamps) for rice cultivation. In Tahle 1. western and central Africa, a limited numher of these Bida fadamas. With few exceptions the hydro- lands are currently being used to grow rainfed rice morphic soils of the inland valleys in central Nigeria without water control. Seasonal deep Hooding have a sandy texture. low pH, low cation exchange frequently damages the crops during the early stage c:rpat:ity and low organic matter content (Table 1.) of growth. Iron toxicity is commt~ni n many inland The mineral in the clay fraction is predominantly valleys, where seepage How contains a high con- kaolinite. Most soils show strong mottling, indicat- centration of ferrous iron. ing seasonal fluctuation of the groundwater table, Research during 1982 focused on seventeen and they have a very low soil nutrient status. High selected wetlands sites in southern and southeastern soil permeability and fluctuating groundwater tahles Tahle 1. Properties of selected hydromorphic soils from inland valleys near Rida and Rende and from Anamhra River alluvial plains near Adani, Southern and Central Nigeria Cat ion Depth. H o r i S a n d , Si l t , Clay, pH Organic Exrhangrah le cat ions , mrq!100 g caps- R~~~ ~ ~ 1 . cm zon '%, '%, '%, (Hz01 C, 'Yo Cn Mg K N a A1 H cit.y, meq/100 g P P ~ Arenic Tropaquept, Gara Fadama, Bida 0 10 AD 68 30 2 4.2 1.10 0.96 0.15 0.13 0.07 0.68 0.04 2.10 9.6 4 2 8 0 + C1 50 46 4 4.3 0.32 0.41 0.08 0.06 0.03 0.61 0 1.22 2.2 Plinthic Tropaquult, Lower Terrace, Adani 0 ,i AU 14 72 14 4.2 1.78 0.60 0.48 0.16 0.06 1.86 0.68 3.94 3.9 Typic Tropaquept, Flood Plain, Adani 0 12 4 v 16 38 46 4.3 1.54 15.60 5.45 0:iX 0.15 0.75 0.04 13.i7 1.5 12 :37 l3 'i 14 38 48 5.4 0.58 6.80 6.45 0.35 0.18 0.14 0 13.91 0.6 3 i 6 0 R3 14 38 48 5.6 0.95 7IiO 6.70 0.19 0.18 O 15.02 0.6 60 100+ C 20 38 42 5.5 0.60 7.00 6.80 0.29 0.21 0.21 0 14.54 0.5 Eutric Tropaqucpt, Inland Swamp, Isi-Ugwu, Bende 0 l:i 1\11 18 33 49 4.6 4.56 23.10 4.42 0.41 0.11 0.35 0.06 28.59 4.5 122 Farming Systems meters 4 and 6). Seepage flow from the side valley also diminishes during the dry season, and a slight dropof the groundwater table in the Fe toxic area allows oxidation to take place in the surface layer during some part of the dry season. Although the Fe toxicity problems of inland valleys and swamps are common, their extent and severity depend largely upon the volume of seepage flow, the source and concentration of ferrous Fe in the seepage water, the groundwater table, and the drainage condition of the valley bottom land below the seepage flow. The hydromorphic soils of the inland valleys near Bende are amon.e> the most wroductive soils for lowland rice cultivation in Nigeria. I t is estimated that severe Fe toxicity occurs in about 5 to lo'%, of the total area study site. Reclamation of this area could be achieved by the construction of a small drainage canal to lead Fe rich seepage water into the main stream. The Fe toxic area is presently being used for screening rice cultivars for tolerance to Fe toxicity.-T. Kosaki and A.S.R. Juo OP Plezometer rites Soil Degradation 11 Alfisols 8 Sept I Dry rearon 115 Decl ~ ~~~ ~~~ (NMmott1e.d zone I FB toxic area has become a serious prohlcm. On land newly cleared (Reductive 1 from secondary forest, cassava frcsh tuber yields of Figure 1. Map and cross section showing an iron toxicity 30 to 40 t/ha were at one time frequently obtained on field in an inland valley near Uende, Nigeria, 1982. .. seepage and groundwater flow. Four piezometers uncommon during the first few years after clearing. were installed along the direction of seepage flow Such yields have become increasingly rare on fields (piezometers 1t o 4). Groundwater data indicated that that have been under continuous, mechanized soils in the iron toxic area (piezometers 2 and 5) cultivation for more than ten years. remain saturated or flooded throughout the growing During 1981-82, a soil fertility survey was made of season. Their soil solutions contain high levels of the main farm blocks a t IITA. Maps showing the ferrous iron, ranging from 20 to 50 ppm (Figures 2 and extent of chemical and physical soil degradation and 3). The highest soluble Fe content was observed in thc nutrient status of the soil are being prepared. The water samples taken from piezometer 5. The high Fe results of this survey will be used in making content is apparently the result of this piezometer's recommendations for soil fertility restoration and proximity to the source of seepage flow and to future soil management. continuous flooding. Of the soil properties analyzed, the ones that The groundwater table in the nontoxic area changed most significantly were soil pH, organic fluctuates markedly during the growing season, as matter and exchangeable Mg (all ofwhich decreased) shown by the data from piezometers 3 and 4. Soluble and bulk density in the surface horizon, which Fe content in the soil solution i n the nontoxic area increased. Information about the dcgraded area and was much lower, ranging from 0 to 5 ppm. remarks on land management are given in Table 2. Analysis of data collected throughout the year Over half of the total area of the experimental farm indicates that the groundwater table in the valley on the East Bank at IlTA should be put under a bottom land varies greatly in depth between the planted fallow or a mulch farming systcm to restore rainy and dry seasons. During most of the rainy adequate levels of organic matter and soil biological season, it remains near the surface. The surface soil activity. Approximately 10 to 15%)o f the total area of is thus enriched by the Fe rich seepage water, the East Bank has been severely acidified, and causing toxicity in the area near the outlets of the magnesium deficiency and/or manganese toxicity seepage flow. During the dry season, starting a t the may limit normal crop growth. These acidified lands end of November, the groundwater table drops should be returned toplantedfallow withdeep rooted gradually to the level of the main stream (piezo- shrubs to recycle the subsoil calcium. An initial Farming Systems 123 Aug Sept Oct Nov Dec application of a small amount of dolomitic lime may I1 18 25 1 8 15 2029 7 13 20 27 5 10 17 24 9 8 I5 also be required to facilitate seedling establishment. Systematic monitoring of soil properties in selected long-term experimental plots (Figure 4 and Table 2) has shown that the extent of soildegradation depends upon the cropping systems and soil manage- ment practices. Land under continuous cereal cropping acidified a t a muchfaster rate than that in a rotation of maize, cowpeas and cassava or in mixed cropping of maize and cassava. Continuous cropping greatly increased bulk density and reduced soil organic matter in the surface soil of all three land management systems. Fields planted in no-till maize with a residue mulch cover maintained a slightly higher level of organic matter than fields plowed by tractor. The decline of soil organic matter and exchange- able Mg in the surface soil (monitored in a long-term continuous cropping experiment) was most striking, particularly when the crop residues were removed after each harvest (Figure 5). Acute Mg deficiency symptoms appeared on young maize plants after the fifth year, particularly on plots where crop residue was removed. This implies t ha t even for the relatively high base-status Alfisols additional inputs of Mg fertilizer and lime may he required after several years of continuous cropping. Data collected over a ten-year period have shown that the rate of decline in Mg was more rapid than Figure 2. Seasonal fluctuation of the groundwater table that of Ca and K. This finding is in agreement with and flooding at various ohservation sites in an inland the ion exchange selectivity sequence of soils swamp near Bende, Nigeria, 1982. dominated by kaolinitic clay minerals. The loss of Aug Sept Oct Nov 1 1 18 25 1 8 15 22 29 7 13 20 27 5 10 17 24 A : Maize/cowpea/cassova rotation, plowed I12 years 1 5 0 ~ 1 1 1 1 ~ 1 1 1 1 1 1 1 ,B 8C 7ontinu ous maize, plowed ( 7 years) C Continuous maize. no-t111( 7 y ears ) I Forest so11( 0 t o 7 5 cm) pH (H20) 6 2 1 Organic C I%) 2.25 Bulkdenslty ( g/cm3) 109 IBulk deknsity A Figure 3. Seasonal fluctuation of dissolved iron in soil -60 solution sampled at various piezometer sites in an inland Figure 4. Changes brought about by continuous cropping swamp near Bende, Nigeria, 1982. in the surface layer of Alfisols at IITA, 1982. 124 Farming Systems Mg from the surface soil is caused primarily by a emphas~zec over crop rotation and the inclusion of reduction in the cation exchange capacity, which economlc tree crops. results fi.on~a decline in soil organic matter. This loss is also caused in par t by increased acidity i n the Ultisols surface soil. Most of t he Mg is leached into the Changes in soil properties of the strongly acidic groundwater because t he kaolinite dominated sub- Ultisols (Typic Paleudult) under continuous culti- soil horizons have li t t le capacity t o absorb it. A vation a t IITA's high rainfall substation a t Onne comparison of soil organic matter and pH levels were also monitored in selected experimental plots. in cultivated soils with those in soils undcr natural 'rhc most pronounced change was the soil compaction and plantedfallow has shown the need for including i n a field t ha t had been under tractor cultivation for an effective fallow phase i n t he cropping cycle t o seven years, a s shown by t h e increase in hulk density maintain adequate soil organic matter levels and t o of both surface and subsurface horizons (Figure 6). prevent rapid soil acidification (Table 3). Research on Improved surface drainage on such fields is needed the management of t he highly erosive kaolinitic to minimize runoff and erosion during hoavy rain Alfisols for food crop cultivation should strongly st,orms. Establishing alley cropping systems on severely compacted ficidsis recommended toimprove Table 2. Information on degraded soils a t IITA's experimental fa rm a t Ibadan, water infiltration. Liming and residue burning would 1982 h e beneficiz~lf or the establishment of leguminous Percen shrubs, which would supply adequate Ca and Mg and taee of eliminate Al toxicity. Soil condition.' total urea Remarks Continuous cultivation has also resulted in a pH (H?O): 15.0 15 Possible Mn toxicitv in decline of soil organic matter in the surface soil, legumes; low rates of lime compared with t ha t in soil under forest vegetation. may he required. Thc land should be placed under There was little diEerence in organic C content cover crops, shrub Pallow or between t he plowed and no-till and mulched fields alley cropping. under the perhumid conditions of Onne. The slightly Organic 60 Severe N and S deficiencies higher pH values of t he cultivated soils were due t,o a carhon : in cereal crops. We recom- liming applied seven years ago a t a r a t e of 1 t /ha. < 1 .XI 'yo mend residue mulch farming The relatively high level of organic carbon (1.8%) with proper crop rotation, and the low pH values (3.7) i n t he surface horizons including cover crops. Alley under forest vegetation a r e common properties of cropping should he practiced h i ~ h l yw eathered acid soils i n the high rainfall nn land with a slope greater tropics. Because most nutr ient cations, such a s Ca, than 4'x or on land occupying the lower Mg and K, a r e being held hy t he forest biomass, the part of the top.o seu.u ence. soil organic mat te r becomes predominantly A1 Exchangeable :35 Mg fertilization may be re- saturated and strongly acidic. Mg: quired to maintain adequate i0. 5 meq/IOO g cationic balance Table 3. Effects of continuous cropping compared with those of natural and planted fallow, IITA, 1972-1982 Organic C, '% pH ( H p ) O to 7.5 to 0 to 7.5 to organic carbon (%I Exchangeable M q (rne$/10Ogi Treatment 7.5 cm 15 cm 7.5 cm 15 cm Fallow (no fertilizer) Bush regrowth.. . . . . . . . . . . 2.81 1.05 6.3 6.0 Guinea grass (ratooned twice a year). . . . . . . . . . . . 2.56 1.26 6.6 6.5 mulch ---- Leucama (ratooned oncea year) . . . . . . . . . . . . 2.68 1.12 6.1 5.9 Pigeon peas (ratooncd or 10 Stover removed replanted oncca year . . . . 1.79 0.84 5.1 5.0 Cropping (fertilizer, no-tillage) 0 5 Maiee/cassava mixed, residue mulched.. . . . . . . . 1.28 0.80 5.4 5.5 Maize, residuemulched . . . . 1.58 1.01 4.6 4.8 0 2 4 6 8 1 0 0 ? 4 6 8 1 0 Maize,rcsidue removed.. . . 0.80 0.65 4.3 4.2 Yeor of cropprng Soybeans, residue mulched . 0.81 0.45 4.7 4.4 Figure 5. Decline in soil organic carhon and exchangeable magnesium in the surface layer ofa fnr.estAlfisol as aresult LSD (5%) for comparing: of continuous maizp cropping with and without crop Treatments . . . . . . . . . . . . . 0.33 0.26 residue mulching. IITA. 1982. Depths . . . . . . . . . . . . . . . . . 0.15 013 a----. Secondary forest or thicket 115 yeorr I In order for t,he results to be valid. the rainfall MM olzelcowpea and maize/corrom mfot#on,n o l i l l o ~ eI B y e a n 1 W Ma~ze/corraualuplond rlce rotetion. troctor Illloge ( 8 y eorr ) simulator has to reproduce acruratcly a given intensity of rainfall for the different soils. After preliminary testing an intensity of 9 cm/h was selected, which could he reproduced with less than 5'%, variation. This high intensity was selected because it represents the more severe rainfall conditions for testing the erodibility of the soil. The test procedure is as follows. The sample is placed carefully into the soil pan in a 6-cm 1;iyer over a screen covered with cheesecloth. Infiltration is measured by thc outflow from holes in the hottoms of 0 0 5 1 0 15 20 35 4.0 1.0 1.5 2 0 the pans, which are tilted a t a 9% slope. Splash Organic C 1%) PHIH~O) Bulhdenrlty(g/cm31 erosion is collected on splash boards placed at each Figure6. F,ffect of cultivation on some properties of a forest side of the pans. Samples of runoff material and U l t i s o l . Onne, Nigeria,,1 982. splash and infiltration water are taken a t five-minute intervals. The runoff samples arc filtered under Residue burning on strongly acidic Ultisols and suction, and the amount of' soil and runoff water Oxisols during forest clearing is heneficial in that it are measured. The samples are stored for further neutralizes soil acidity and permits quick release of analyses. Samples of infiltration water are analyzed nutrients such as Ca, Mg and P from plant for nutrient losses. The soil sample (air-dry) is residues.-A.S.H. Juo and C. van der Meersch subjected to a one-hour rain, allowed to come approximately to field capacity and then subjected to Soil Erodibility 80 minutcs of rain. Fifty-six topsoil samples were taken at 27 different Several attempts have been made to assess the locations in Nigeria. These soils come from different erodibility of soil. Although it is best estimated by agro-ecological regions of the country and have the unit plot technique under natural conditions, contrasting physical and chemical properties. The this method is expensive and time consuming. In samples have been air dried without sieving. Since other studies, nomograms have been developed that this study is still in progress, only the results for one can predict relative erodihility from measurahle soil soil sample can be given. The intensity of the rain properties both under natural and simulated con- was 8.17 cm/h for the dry and 9.00 cm/h for the wet ditions. These methods need to he tested on tropical run. Differences in rainfall intensity were due to soils. differences in hydraulic head in the reservoir. The Soil erodihility is a function of both the detach- comparison between the wet and dry run was made to ability and transportability of a soil and can be determine the magnitude of the effects of antecedent evaluated by various laboratory methods, although soil moisture content on splash and sheet erosion. it is not known whether the various detachability Results for the different soils will provide a basis indices are appropriate fur tropical soils. In this for comparing the various detachability indices that study the correlation between various detachability will be examined (instability index, Henin index, wet indices and soil erodibility, as measured by rainfall sieving. water stable aggregates, dispension ratio, simulation, is being evaluated for some Nigerian etc.). These tests are now being conducted for the soils. These measurements of soil erodibility will be 56 soil samples collected. In the near future, we plan compared with estimates obtained by using the to use a field rainfall simulator for comparing nomograph. For many erosion studies, simulated laboratory results with in-silu measurements. A . rainfall has great advantages over natural rainfall. Vunelslande, R. La1 and D.G abriels It produces results more rapidly and efficiently and provides the desired information under more con- trolled conditions. However, the characteristics of Organic Residues and Fertilizers natural rainfall must be simultated as accurately as Most of the field experiments on organic residues and possible, and in order for the results to be inter^ fertilizers were carried out at four sites in Nigeria: pretated properly, the limitations of the method must the IITA main station a t Tbadan on an Egbeda series be clearly established. soil (Oxic Paleustalf);I ITA's substation at Ikenne on The rainfall simulator being used in this experi- an Alagha series soil (Oxic Paleustalf); IITA's sub- ment was developed attheLahoratory of Soil Physics station at Onne on an Ultisol (Typic Paleudult); and of the State University of Ghent, Belgium, by Mokwa, which has a very sandy Oxic Paleustalf. Gabriels et al. The main part is an applicator tank with 96 drop formers placed spirally in the bottom of Effect of Plant Residue Mulching and the tank. The intensity of the rain is controlled by Burning changing the hydrostatic head above the drop Burning of plant residues is part of seedbed formers. preparation in traditional farming systems. The 126 Farming Systems effects of this practice on soil productivity and crop burning (1.1 1 g/cc compared to 0.95 g/cc for the bush performance have never been adequately studied. plot). There was more earthworm activity in the Two trials were started in 1978 on an Alfisol (Oxic mulched than in t,he burned plot. -O.T. Kang Paleustalf) at Ikenne and on an Ultisol (Typic Palendult) at Onne to investigate the effects of Leaf Decomposition annual burning of plant residues before each main Psophocarpus palus t r i~a nd Gliricidia sepium. season ~ lan t ingT. he trials included a study on the Decomposition of leaves of these species was studied effects of mulching with the residues. The experi- a t IlTA on flat laud cleared of vegetation and litter. ments were carried out through 1982, using a split- Fresh bipinnate leaves of gliricidia and trifoliates plot design with four replications. A maize cowpea of psophocarpus were collected and dried at 50" to annual rotation has been used throughout that 60°C in an oven. Subsamples (about 60 leaflets) period. were weighed and confined in insect proof nylon bags At Onne on the Ultisol, the main season maize 30 cm x 40 cm of 32 mesh size and nylon nets of 2-cm yield declined to low levels without fertilizer and mesh size. liming in the fifthcropping year. With an application For each legume, bags and nets were secured in the of N, P, K, Mg and Zn, the burned plots gave slightly field during the rainy sesson in a four-replication higher yields than the mulched plots, but when lime split-plot design, with three pesticide treatments was also added every other year, the mulched plots (control without pesticide, 0.1591, thiodan and 0.1% gave higher yields. Results from five years showed benomyl) as the main plots and sampling time as the that withminimum tillage, application of N, P, K, Mg subplots. The latter consisted of five randomly set and Zn, biannual liming, and annual rotations, high bags and five nets. Every 10 days one bag and one net maize yields of over 3.0 t/ha can be sustained on the were collected in each subplot for each legume. They acid Ultisols at Onne. were dried a t 60°C until constant weight. 1,oss of dry The 1982 maize crop in the Ikenne trial produced weight and changes in N and P content were then much lower yields than in previous years primarily determined in each sample. because of poor rainfall (Table 4). Though burning The weight loss in nets of psophocarpus was and mulching did not differ significantly in their 1.4 times more than in bags (Figure 7). Insects, effect on yield. the inulched treatment gave a slightly physically screened from the bags, apparently played higher yield with NPK applicat,ion. an important role in biodegradation of' leaves of this The burned plots had a higher percentage of plant legume. This finding was corroborated by the slow establishment. The lower plant establishment in the decomposition of psophocarpus leaves in nets treated mulched plots was due mainly to rodent damage. But wit,h thiodan. However, because the rate of weight even though the plant stand was decreased by over loss was higher in nets of psophocarpns leaves XI%,, the yield of the mulched plot was equal to or treated with insecticide than in bags, one could slightly higher than that of the burned plots. It is assume that thiodan was not totally effective in therefore likely that higher yields could be obtained suppressing the insects or that its toxicity was from the mulched plot if the plant stand were not maintained throughout the experimental period. improved. Other factors may have been involved, such as Measurements of the physical properties ofthe soil removal of pieces of leaves by wind and rain. showed that under minimum tillage, the bulk density Comparison of weight loss in hags and nets of remained low with both residue mulching and gliricidia leavcs and the effect on this loss ofthiodan indicate that insects were unimportant in biodegra- 'T;&hlc. 1. F:Brc.t of plant rviiduv m;rnagrrnc.nt iand dation of leaves of this legume (Figure 7). Figure 7 I'1.1.1ili7vorn m;~in.; e,;~soom ail- (l '%I'I1) also shows that bcnomyl retarded dcco~npositiono f yield, Ikenne, Nigeria, 1982 leaves, particularly of psophocarpus, in the nets. Yield, kg/ha Isolation of fungi colonizing hoth gliricidia and Residues Residues psophocarpus indicated qualitative differences be- Fertilizer treatment mulched burned Mean tween treatments; these were observed in the Control . . . . . . . . . . . . . . . . . . . 2,507 2,499 2,503 microscope and were indicated by mycelia and spore PK. . . . . . . . . . . . . . . . . . . . . . . 3.632 3,798 3,716 color on acidified potato dextrose agar plates. NK . . . . . . . . . . . . . . . . . . . . . . 2.788 3,117 2,953 Figure 8 shows that after 20 days decomposing NP . . . . . . . . . . . . . . . . . . . . . . . 3.948 3,5!!4 3,736 leaves of psophocarpus contained less than 5Ocj; of NPK . . . . . . . . . . . . . . . . . . . . . 4,056 3.899 3,978 their initial N and P. The same trend was observed NPK, mg and Zn . . . . . . . . . . . 4,105 3,943 4,024 for gliricidia. The rapid rate and large extent of' N Mean . . . . . . . . . . . . . . . . . . . . . 3,506 3.463 and P loss are important considerations when these LSD (5%J for comparing: legumes are to be used as live mulch or in alley Residue management means . . . . . . . . . . . . . . . . . . . 739 cropping. Thiodan and benomyl had little eEect on N Fert. treatments under same residue mgmt . . . . . . . 576 and P loss but stimulated P immobilization. Fert. treatments under differentr esidue mgmt. . . . 885 Another experiment was conducted in the dry "Mean plant stand of maize with residue mulched was 77.0%, and season to assess the effect of rainfallon the loss ofdry wirh residue burned 95.9'70, with n n IS11 (SY,)u f 11.2'%,. matter and N during decomposition of P. palustris Farming Systems 127 Dry welght ( % I Dry weight (%I 100 G/IIICC~,/One /sl Bog 1rngotion 60 40 Control 40 20 20 0 0 20 40 60 0 20 40 60 0 20 40 60 0 20 40 60 Days Doyr Figure 9. Etfrt:t of irrigation and pesticides on dry matter Figurc 7 . E ffects ofhenomyl and thiaclan on the dry weight during decomposition of leaves of Psophocarpuspnlustris. uf decomposing leaves of Cliricidiu seapium and Psopho- TTTA, 1982. carpuspalustris in nets and bags (expressed as a percentage of the initial weight), IITA. 1982. psophocarpus leaves. Dry matt,er and N content decreased faster in nets than they did in insect proof Phosphorus ( % I hags because plant materials are removed from the former by insects and wind and more are lost during handling. Because of the high rate of dry matter loss in nets, the effccts of irrigation and pesticides were not evident. Other plant species. The decomposition of leaves of selected plant species was studied at IITA and Onne to determine their potential as a source of nitrogen and as mulch materials. 1,eucaena and N~trogen(%l Fi psophocarpus decomposed more rapidly than the other species (Table 5). The leaves of the latter had only 6%) of their original N content after six weeks 60 of decomposition a t Onne and 21%) a t IITA. Because of it,s high N content and its fast growth and 40 \ \ '. decomposition rate, P. palustris is appropriat,~fo r \-- live mulch systems. Leaves of gmelina, cassia, acioa, 20 - treculia and centrosema are also adequate for that 0 purpose. Of these, centrosema, and to a lesser extent, 0 20 40 60 0 20 40 60 gmelina and cassia, could serve as sources of Days nitrogen as well.-K. Mulongoy Figure 8. Effects of henomvl and thiodan on nitrorren and phbsphorus content of dkcomposing leaves of 'sopho- Nitrogen Response With Different cnrDu.s~alustrisinnetsandh ars(exwressed as a werrentaze of&e initial nitrogen and p h o ~ ~ h o ~ ~ ~ s c o n t19r&n t ) , ~C~ r~o~p,p ing Systems An experiment was carried out a t Onne on land that leaves. A four-replication split-plot design was used, had been in bush fallow (mainly Anthonata and with irrigation (equivalent to 0 and 8 mm rainfall Alchornea) for over 12 years. The plot was hand per day) as the main plot and pesticide treatment cleared (not destumpedj and partially burned before (control, thiodan and benomylj as the subplot. From cropping, as is done by traditional farmers in the five bags and five nets of leaves, one hag and one net area. The trial was conducted using a randomized were collected every 10 days. complete hlock design with four replications. Irrigation accelerated the loss of dry matter and N The response of maize to nitrogen was very in the hags (Figure 9). This loss was reduced in the significant (Figure 10). Monocropped maize (at a presence of thiodan and benomyl, confirming that population of 40,000 plants,'ha) responded signifi- insects and fungi participate in thedecomposition of cantly t o N rates of up to 135 kg N/ha. Maize (at a 128 Farming S,ystems Table5. Field decomposition of leaves of selected Gram yield ( l / h a 1 olants. IITA and Onne. Nigeria. 1982 %, dry matter percent N NO. of days after 6 wk before until SO%, of decomp. decompo N loss Species IITA Onne sition IITA Onne Crnelina arborea. . . . . . 78.9 77.9 2.23 > 42 >42 Cassia siamca . . . . . . . . 79.7 94.4 2.66 > 42 >42 Acioa barter i . . . . . . . . . 8 7.2 88.7 1.74 > 4 2 > 4 2 Treculia africana . . . 8 1.2 76.5 1.99 >42 >42 Cl ir ic idia sepium . . 64.0 61.2 3.80 21-22 12 Leucaenn lcucocephala. 61.5" 21.(i" 3.35 26 27 22 Psophocarpus pa lns t r i s 64.7 21.8 5.96 11-12 6-7 ('entrtisema ouhescens . 83.1 72.7 4.44 19 20 11 LSD (S'K,). . . . . . . . . . . . 12.3 18.0 1.60 4 3.6 "The low dry weight may hnvc resulted fkom loss of leaves during handling. plant population of 10,000 plantslha) intercropped with cassava (at a population of 10,000 plants/ha) gave lower yields under the low light intensity conditions a t Onne. The low yields were caused by the shading effect of the vigorously growing cassava crop, which may also have heen the reason that maize responded significantly only to the lower nitrogen rate of 45 kg N/ha. Additional nitrogen applications gave no further yield increases, ;md yield actually seemed to decrease a t the highest N level of 180 kg/ha.-A. u a n d er Kruijs, J . u a n d e r Heide a n d U.T. Kang Figure 10. Effect of'n itrogen rates on yield of mrrnocroppcd and mixed cropped maizc on newly cleared land, Onne. Evaluation of Nitrogen Sources Nigeria, 1982. A trial was conducted a t Onne o n cropped land using a randomized complete block design with four Grain yield ( t/ha replications. Nitrogen was applied in three dosages. 4 . 0 Maize yield responded significantly to nitrogen up to a rate of 135 kg N/ha on this heavily cropped land (Figure 11). Though maize yield was not significantly affected by method of nitrogen application or by nitrogen sources in this trial, i t appears t ha t ordinary urea is slightly better than urea super- granules or CAN. An experiment was conducted on cropped land a t Ihadan to test the effectiveness in a no-tillage system of urea, urea supergranules, and c:ilcium ammonium nitrate placed hy various methods. The experiment was carried out using a complet,e randomized block design with thre i replications. Prilled urea was less effective when hroadcast or surface banded than when applied in a band and covered or applied in ;I hill (Tahle 6). Yield increased significantly when prilled urea was applied a t a rate of 120 kg N/ha in a hand and covered and when i t was applied a t the lower rate of 60 kg N/ha in a hill. With calcium ammonium nitrate, broadcast application :rlso appears to be least effective. Calcium ammonium nitrate significantly increased yield when applied a t 0 120 kg N/ha in a hand a t the surface or when covered 0 4 5 90 135 180 and also a t the lower rate of 60 kg N/ha when applied Nitrogen rate (kg/ha) in a hill. Urea supergranules significantly increased Figure 11. Efiecl of nitrogen sources and placement yield when applied at a rate of YLO kg N/ha in a hill. methods on maize yic.ld,O nnc. Nigeria, 1982. Farn~ingS ystems 129 With hill placement prilled urea, calcium ammonium Table 6. Effect of nitrogen source and placement nitrate and urea supergranules appeared to he method on maize (TZPR) Yield, IITA, 1982 equally effective, though urea supergranules have Calcium Urea. the advantage of easier handling and application. Mcthod and rate of' Prilled ammonium suger~ The lower effectiveness of surface applied urea and nitrogca application urea nitratr granulrs calcium ammonium nitrate may be due to surface Broadcast, runoff and, with urea, possibly to volatilization, as 60 kg/ha . . . . . . . . . . . . . 3,:i41 was observed in earlier trials.-B.T. Kar~g,A . van 120kg/ha . . . . . . . . . . . . 3.580 der Kruijs and J. uan der Heide Surface handed 60 kg/ha . . . . . . . . . . . . . 3,148 Phosphorus Requirement of Cowpeas 120 kg/ha . . . . . . . . . . . . 3,624 Banded and covered The phosphorus requirement of three early maturing 60kdha . . . . . . . . . . . . . 3,570 cowpea varieties (IT 82-32, 82E-9 and 82E-60) and one 120 kg/ha . . . . . . . . . . . . 4.033 intermcdiate maturing variety (VITA-6) was studied Hill a t lkenne. The surface soil had a low Bray P-l level of 60 ky/ha.. . . . . . . . . . . . 3,710 :3.710 3.668 4.2 ppm. The experiment was set up in a randomized 120 kg/hn . . . . . . . . . . . . 4,068 4,068 :i,l)R9 complete block design with four replications. Control (no nitrocen) . . . 3.108 Despite the low initial soil phosphorus status, the four varieties did not respond to phosphorus application. The three early maturing varieties had Tahle 7. Nitrogen and potassium response of cassava significantly higher mean yields than VITA-6 (505 varieties, Onne, Nigeria, 1982 kg/ha). Of the three, IT 82E-9, which is hlack seeded, Tubcr yleld. t/ha gave the highest seed yield of 1,210 kg/ha. A11 four Treatment. kg/ha TMS TMS TMS TMS varieties nodulated well a t Ikenne. Phosphorus N K 30572 30555 4488 30337 Mean applicat,ion significantly increased nodule numbers and weights a t three weeks aft,er plant,ing. However, a t six weeks after planting, phosphorus application differencesln dry nodule wkight between V~TA-6I,T 823-32 and IT WE-9; all three varieties showed sig- nificantly higher dry nodule weight t,han IT 823-60. R.T. Kang, A. Ayanaba and B.B. Singh Nitrogen and Potassium Response of Cassava A nitrogempotassium trial hegun in 1980 with four cassava varieties on a Typic Paleudult a t IITA's 150 Onne substation was repeated in 1982. The experi- ment had a factorial design with four replications. Mean All four varieties showed some dieback and tuber LSD (5'%.) rot a t harvest. The low yields of TMS 4488 and TMS 30377 were due mainly to a high percentage of Sources and Management of missing plants and tuher rot caused by the high Phosphorus and Nitrogen rainfall a t Onne (Tahle 7). Yield analysis showed The International Fertilizer Development Centre significant differences between varieties. TMS 30572 (IFDC) and IITA started a cooperative research gave the highest tuher yield, with a mean of 21.0 t /ha, program in 1982 to find better, more economic followed by TMS 30555, 4488 and 30337 with mean sources of phosphorus and nitrogen fertilizers and to yields of 18.4, 17.5 and 13.3 t /ha, respectively (Table study their management in the humid and subhumid 7). TMS 30555 gave the lowest tuber yield of the four tropics of Africa. One alternative being considered varieties in the first trial. to t he expensive soluble P fertilizers is direct Statistical analysis of the nitrogen and potassium application of phosphate rock t o some acid soils. This responses showed no significant differences in tuher nption has received much attention for several yield. However, as observed in the first crop, the reasons. First , extensive areas in developing average tuher yield tended to he higher with countries are characterized by acid soils that are potassium application, particularly for TMS 30572 high in phosphorus fixing capacity. Second. where and TMS 30555 (Tahle 7). Data on the dry matter deposits of phosphate rock exist, it takes much less percentage of' tbe tuhers showed a significant capital investment and foreign exchange to use the increase with potassium application and a decrease rock for direct application than to import soluble with nitrogen.^-B.T. Kang and A.S.R. J u o fertilizers. 130 Farming Systems In using phosphate rock, one has to recognize the there than in the savanna. The base saturation on the importance of soil pH since acid conditions are undisturbed topsoil is very high but decreases with required for dissolution of basic calcium phosphate. increasing depth. These soils are Oxic Paleustalfs. Direct acidulation of phosphate rock, using a The objectives of the joint IFDC/IITA phosphorus fraction of the sulphuric acid needed t o produce experiments are to determine the effectiveness of single superphosphate, yields a P fertilizer that finely ground Togo phosphate rock in food crop combines many of the desirable properties of the production, the effectiveness of partially acidulated soluhle P source and the P rock. These intermediate Togo phosphate rock as a source of both phosphorus products dcveloped by IFDC arc referred to as and sulfur for food crops and the most appropriate partially acidulated phosphate rock. Their effective- phosphorus fertilizer sources for improving food crop ness is much less dependent on soil pH. production economically. Little is known about the fate of fertilizer nitrogen Different rates of phosphate materials, including applied to field crops such as maize in the humid and partially acidulated rock (with sulfuric acid) subhumid tropics of Africa. The use of ' W as a tracer prepared a t IFDC, were used in experiments a t both allows us to quantify accurately the utilization of Ikenne and Mokwa. The treatments included (1) fertilizer N by the crop, retention of it by the soil, and phosphate rock applied annually, (2) phosphate rock thc amount of i t lost from the soil-plant system. applied a t three times the rate of the annual lncorporation of '"N in different fertilizer treatments application, (3) 25% partially acidulated phosphate will help identify N sources or management practises rock, (4) 6 0 ~ p~a/r,t ially acidulated phosphate rock, (5) that favor N utilization by the crop and reduce N single superphosphate and (6) triple superphosphate. losses. Sources 1, 3 , 4 , 5 and 6 were applied a t the rates of The first series of experiments was established 0, 30, 60 and 90 kg PzOs/ha. All the phosphorus at Ikenne and Mokwa, Nigeria. Mokwa is in the fertilizers were broadcast and incorporated to a southern Guinea savanna, where the rainfall is depth of 3 to 6 cm. Nitrogen, magnesium and zinc monomodal and averages 1,500 mm over five to seven were applied a t 120 kg N/ha, 10 kg Mg/ha and 2 kg months of the year. The soils at the experimental site Zo/ha. The urea applied in treatment 5 was labelled are sandy, and the downward movement of clay with 5% 15N to permit construction ofthefertilizerN within the profile niakes the subsoil higher in clay. balance. The maize variety TZPB was planted at The clay is predominantly kaolonitic. The soils are spacing of 75 cm x 25 cm during the major season in Paleustalfs, with ra ther low cation exchange plots of 8 m x 4.5 m. The treatments were replicated capacity and organic matter content. five times in 5% randomized complete block design. lkenne is in the subhumid forest zone, which Atrazine was applied to control weeds. In the minor receives an average of 1,500 mm of rainfall per year in season (Ikcnne) or after maize had started silking a bimodal pattern. The soils a t the experimental site (Mokwa), cowpea variety VITA-5 was relay planted are sandy, and the clay content increases with depth. a t Mokwa and sequentially planted after maize at The clay *action is mainly kaolinitic and contains Ikenne. The cowpea crop did not receive any iron and aluminum oxides. Leaching is more intense additional fertilizer. Maize grain yield ( t / ha ) 4.5 4.0 3.5 0 0 30 60 90 0 40 80 120 0 40 80 120 90 180 270 Kg P205/ha Nitrogen ( kg/ha) Figure 12. Effects of sources and rates of nitrogen and phosphorus on maize yield at two locations in Nigeria, 1982. Farming Systems 131 At Mokwa, phosphorus application had no effect onmaize yields or on the P content of the maize index leaves. At Ikenne there were no increases in P content of the maize index leaves but maize yield did respond to phosphorus (Figure 12). At both locations cowpea yield did not respond to phosphate appli- cation. Growt,h and yield of the cowpea crop a t Mokwa was markedly reduced because of the shading effect of the maize. Generally, cowpea yields at Ikenne were higher hecause the crop was sequentially planted there. Since there was so little response to P, thesc experiments did not permit a proper evaluation of the phosphate sources. The experiments will be continued to evaluate residual effects, and new ones will begin a t sites known to be responsive to P. The fertilizer N balance has not yet been constructed but will be once plant and soil samples have been analyzed for 15N. Both experiments will include a 0 second 15N balance experiment next year. Percent nitrogen of ear leaf Nitrogen trials were laid out at Mokwa and lkenne to compare the N efficiency of various N sources and fertilizer management practices (modified products such as urea supergranules were tested) and to determine the utilization of N in maize/cowpea relay cropping systems (Mokwa) and the residual efYect of N applied to maize on cowpeas in maize/cowpea sequential cropping (Ikenne). In two experiments different sources and ways of managing IFDC's modified nitrogen fertilizers were examined in the field. The treatments were as fol- lows: (1) calcium ammonium nitrate (CAN) was split and broadcast into the soil, one-third at two weeks after planting and two-thirds at six weeks; (2) urea was split and broadcast just as in 1;( 3) urea was split and banded 6 cm deep and ahout 8 cm from each row marked with a hoe, one-third at two weeks after planting and two-thirds a t six weeks; (4) urea super- granules were split and placed on the hill (one-third was spot placed in each hole 6 to 8 cm deep and about Nitrogen (kg/ha) 8 cm from maize hills two weeks after planting, and Figure 13. Effects of sources and rate? of nitrogen on two-thirds was spot placed a t six weeks); and (5) urea cowpea yield, Mokwa, Nigeria, 1982. supergranules were all placed in holes 6 to 8 cm deep and about 8 cm from maize hills at two weeks after fertilizer N application (Figure 12). planting. These experiments seem to indicate that split The nitrogen rates for all the sources and manage- application of N improves maize yield. However, full ment practices were 0,40,80, and 120 kg/ha. A basal evaluation of the various N sources and management application of phosphorus and potassium was made practices requires further chemical (IsN) and at planting a t a rate of 90 kg P205/ha and 90 kg statistical analysis. K20/ha. No fertilizer was applied to the succeeding Cowpea yield did not respond to N application at cowpea crop. All the treatments were replicated five Ikenne. At Mokwa higher nitrogen rates resulted in times in a randomized complete block design. The higher maize yield, causing the maize crop to shade index leaves were sampled at silking for the maize the cowpeas during their early growth and reducing tissue and a t midflowering in the cowpea trial. cowpea yield (Figure 13). The highest cowpea yields At lkenne the nitrogen levels in the index leaves were in the control (no nitrogen) plots where there were not significantly ditf'erent. They were very high, was low maize growth.-S.K. Mughogho averaging around 3.470/,, probably because the site had been under fallow. Maize yields responded Leaching and Utilization of Nitrogen significantly to N in the first season. At Mokwa the Rapid loss of fertilizer N through leaching is a major percent N of the maize index leaves greatly increased constraint on crop growth in the frequently highly (Figure 13), and yield responded well to increased permeable soils of the humid tropics. Field and 132 Farming Systems lysimeter studies were continued this year t o Calc ium cyanamide as a n i t rogen fertilizer. evaluate leaching and crop utilization of diffkrent N Calcium cyanamide (CaCN2) has been unpopular sources. with farmers of the temperate regions because of its Ni t rogen leaching a n d recovery. Field experi- slow rate of hreakdown and transformation into ments on leaching and crop recovery of N from nitrate in the soil. However, these characteristics different N fertilizers were conducted a t Onne. which may he beneficial for excessively welldrained soils in is in the perhumid region and has an annual rainfall the highrainfall tropics. I n lysimeter and greenhouse of 2,400 m. Two cropping sequences, maize (first experiments conduct,ed during 1982, the rate of season) and upland rice (second season) and upland leaching and effectiveness of CaCN2 as a source of N ricelmaize were used. Three N sources were applied: was evaluated for crops grown in a well-drained acid urea, calcium ammonium nitrate (CAN) and am- Ultisol (Typic Paleudult) a t Onne. monium sulfate (AMS). N rates were 150 kg/ha for A lahoratory leaching study, using undisturhed maize and 120 kg for rice in split applications. soil columns (12 cm in diameter and 100 cm deep) of The results of these experiments from the first the Onne soil (pH 4.3), showed that CAN had the cropping season of 1982 (March to June) are given in highest leaching rate , urea a somewhat lower rate Table 8. Judging from yield and N recovery by the and calcium cyanamide the lowest after the columns crop, urea was a hetter source of N than CAN and had been leached with 2,400 mm of water through a AMS for first season maize. The three N sources made rainfall simulator over a period of 42 days (Figure 14). no significant difference in yield of upland rice. The rate of application was 24 meq N per soil column. although rice plants recovered considerably more N Only a small amount of NHsN was found in the fkom AMS than from CAN and urea. leachate, accounting for ahout 3% of the total Because of t he poor growth and yield of second amount of N added to the soil. Most of the NHcN was season maize and upland rice, t he three N sources still retained in the soil column after leaching, made no significant difference i n yield and N indicating that NH4-N was released from calcium recovery. The poor growth and yields were due partly to severe stem borer damage. Upland rice also had Table 8. Effect of nitrogen sources on leaching and utilization of fertilizer nitroeen bv maize poor grain filling in the second season (July t o Octoher). The estimated total recovery of applied N hy the crop and soil (0 to 120 cm) a t the end of' the first cropping season (Table 8) showed that for upland rice source kg/ha and stover solf(0-li0 cm) ammonium sulfate gave the highest total recovery (71%,) whereas for maize total N recovery from urea Maize (TZPB) (61%) was considerably higher than from CAN and Control. . . . . . 1,130 AMS.-Y. Arora and A.S.R. J u o CAN . . . . . . . . 3,070 Urea . . . . . . . . 4,562 51 61 Ni t rogen fertilizer efficiency. A field experiment AMS . . . . . . . . 3,929 27 SO was begun in 1982 on an Alfisol (Egheda Series, pH LSD (jcy0). . . . 658 13 5.8), t o determine the efficiency with which maize Upland rice (ITA 118) uses nitrogen from three sources-calcium am- Control. . . . . . 974 - - CAN . . . . . . . . 2.978 :in 50 Urea . . . . . . . . 2,441 29 36 sources on soil acidification undcr two cropping AMS . . . . . . . . 2.612 40 71 systems, a maizejmaize and a maize/cowpea rotation. In cooperation with the IFDC, microplots with '"N "Nitrogen was applied at a rate of 150 kg/hi%f or maize and labelled CAN and urea were established in the field. 120 k g l h i ~fo r rice. The rate of N application was 150 kg N/ha. Yields of maize and cowpeas are given in Table 9. Table 9. Effect of nitrogen source on maize and The first season maize (TZPB) responded signifi- cowpea yield and recovery of nitrogen by cantly to N application, but the N source had no maize, IITA, 1982 significant effect on maize yield. The results of 16N Yicld, kg/ha %, N re- analysis showed tha t maize (grain plus stover) First Second covered by recovered 33% of the N from urea and 50'x from season season first season CAN, indicating that the latter was the more efficient N source maize maize Cowpeas maize N source for maize growing a t Ibadan. Check. . . . . . . . . . . . Second redson maize suffered severe drought stress CAN . . . . . . . . . . . . . resulting fiom poor rainfall distribution in 1982 and Urea . . . . . . . . . . . . . 3,878 1,334 1,001 33.7 did not respond significantly to N application. The AMS. . . . . . . . . . . . . 4,342 1,222 921 ~- average yield of second season cowpeas (VITA-1) was - - ~ about 1 t / h a without fertilizer application.-Y. "No i'ertilizer was applied r,o second srnson cowpms. In both Arora, A.S.K. Juo. P.Z.C. Vlek and S. Mughogho seasorw maim received 150 k g N/ha in two split applications. Dry matter (g/pot) I I I m NO3- Urea CK CA UR CN CK CA UR CN CK : Check, No N UR : Urea CA: Colc\urn ammonium CN: Colclum cyanomide nlfrate Figure 15. Dry matter yield of five-week-oldm aize and rice seedlings that receivcd 150 mg N/kg uf soil fiom thrce nitmgen snur.ces . TITA, 1982. In the lysimeter study conducted a t Ihadan, using monolith lysimeters with Onne Ultisol, N leaching and utilization of calciunl cyanamide and urea hy upland rice were compared under a simulated Onne rainfall regime. An amount equivalent to 150 kg N/ha was added to each lysimeter (three replications). Urea was applied in three splits, and CaCN2 was applied two weeks before sowing to allow sufficient Figure 14. Leaching and retcntion nf NH4N and NOI-N time for its breakdown and transformation into from three different nitrogen sources (expressed as a NHCN and N03-N. The surface soil (0 to 10 cm) also percent.age of total nitrogen added to the undisturbed soil received 3 t /ha of powdered firur weeks columns), IITA, 1982. The soil columns were leached with before sowing, and soil pH was raised from 4.3 to 6.0, 2,400 mm of' water. as measured a t the time of sowing. Yields and amount of N leaching, given inTahle 10, show that for upland cyanamide slowly during its breakdown in the soil. rice grown under simulated high rainfall conditions The ahsence of nitrate in both the leachatc and soil CaCNa was just as effective as urea, even though i t suggests that nitrification of NH4-N was inhibited was applied only once before planting. hy the presence of appreciable amounts of free Because of its "resistance" to leaching and its use- cyanamide in the soil during the six-week period. fulness as a preplant herbicide, calcium cyanamide In greenhouse and lysimeter studies of the Onne may prove to he a superior nitrogen fertilizer for food soil (limed to pH 6.0), calcium cyanamide was crop production in the humid tropics. J . L . P leysier, evaluated as a source of N for plants. In the Y Arora, A.S.R. Juo and T.L. Lawson greenhouse study, calcium cyanamide was compared with CAN and urea on upland rice and maize. The application rate was 150 mg N/kg of soil. Urea and Seedbed Preparation and Tillage CAN were applied a t sowing. Calcium cyanamide was applied a t one week and again a t two weeks Effects of Tillage and Residue Mulches on before sowing and a t sowing to determine the time Soil Properties required for its breakdown and to eliminate its A long-term tillage experiment was begun in 1971 to herbicidal effect on seed emergence. The plant dry compare no-tillage and conventional tillage, with matter yield of five-week-old plants (Figure 15) and without mulch consisting of crop residues. The showed that calcium cyanamide (applied one week plots have been cropped continuously to maize, with before sowing) was just as effective as urea and CAN two crops per year. Twenty-four maize crops were in the greenhouse, where leaching of urea and CAN grown in succession through the end of 1982. This was prevented. year a study was done on differences between the 134 Farming Systems Table 10. Leaching of mineral nitrogen and yield of upland rice in monolith lysimeters, IITA, second season, 1982 Grain Straw Amount Nitrngen source yield. yield, of NO3-N No tillage/mulch (7,500 mg N g/lysi g/lysi- Drain in leach- ETM? per lysimeter) meter meter age ate, mg" mm Tillage/mulch Urea. three split applications.. . . . 106 178 241 3,192 603 .No tillaae/no mulch CaCN2, one appl. 2 wk hefore sowing. 94 135 236 2,841 601 LSD(5"/c,) . . . . . . . . . ns ns ns ns ns 'The content of NH,-N in the leactrate was negligible, and the total amount was less than I%, of NO3-N. bMaximurn evapotranspiration over the growing period. various treatments in some soil physical properties. Undisturbed core samples were taken a t 10-cm intervals to a depth of 80 cm, and moisture retention and total porosity were analyzed. The pH curves a re shown only for the 0-to-10-cm and 10-to-20-cm layers (Figure 16). Regardless of the mulch treatment, the moisture retention of the untilled soil a t a depth of 0 t o 10 cm was greater than that of the conventionally tilled soil. The e d a p h o l ~ g i c a l ls~ig nificant soil moisture retention a t 1 bar suction and a depth of 0 to 10 cm was 45% for no-tillage with mulch and 44% without, and 34%, for conventional tillage treatments with mulch and 29.6%, without. The total porosity a t a depth of 0 to 10 cm was 49.6 and 48.0%, for no-tillage and 39.2 and 38.4'%, for conventional tillage. These data show that the no-tillage treatments had a greater available-water storage capacity than the plowed treatments and that storage capacity is improved hy residue mulch. The pF curves for soil a t a depth of 10 to 20 cm were not as clear as those for soil a t 0 to 10 cm (Figure 16). Nevertheless, the soil from the no-till plots retained Volumetric moisture content (cm3/cd) more moisture than that from plowed plots a t most Figure 16. Etfects of tillage methods and mulching on pF suctions. This favorable moisture retention with the curves, ITTA, 1982. no-tillage system is probably due to the higher organic matter content in the surface layer, the seeding. The experiment had a split-plot design with better soil structure and the higher earthworm three replications. The tillage treatments were the activity, which result in better maize yields under a main plots and fertilizer treatments the subolots. ITA no-tillage system.-R. La1 and 0. Opara-Nadi 118 w i s seeded a t spacing of 25 cm betweenand 20 cm Tillage and Fertilizer Interaction in Upland Rice a rate of 4 kg/ha. The rice yields a t Ibadan and Onne are shown in Experiments on upland rice were conducted both a t Figure 17. At Ibadan yields were significantly Ihadan and Onne to investigate t he effects of affected by tillage methods, fertilizer levels and the different tillage methods on the water and fertilizer interactions between them. The conventional tillage use efticiency of the variety ITA 118. Three tillage system yielded more than the no-tillage, with and methods were used: (1) conventional tillage in- without mulch, by 34 and 25%,, respectively. The volving plowing and harrowing, (2) no-tillage with response t o fertilizer was also much higher in the chemical weed control, and (3) no-tillage plus straw conventional tillage plots. It should be noted that mulch a t 4 t /ha. There were three fertilizer treat- this experiment was conducted on plots that had been ments: (1)a control without any fertilizer, (2) 45 kg N, cultivated by conventional tillage for about 10 years 6.5 kg P and 7.5 kg K/ha and (3) 90 kg N, 13 kg P, and and were in poor condition. 15 kg K/ha. All no-till plots were treated with Rice yields a t Onne were higher than a t ibadan, paraquat a t the rate of' 2.5 l /ha one week before and the general trends in the response of the crop to Farming Systems 135 tillage methods and fertilizer levels were somewhat different (Figure 17). Conventional tillage outyielded no-tillage with and without mulch. The fertilizer responses were highest with conventional tillage, followed by no-tillage with mulch. These experi- ments will he continued a t Onne and lkenne in 1983. -lbodon Once m w Conventlono1 tlllage W w No-t~llage HN o tliloge t mulch To the yield data will be added ohscrvations on root growth and water u p t a k e . M. Ogula, R. La1 and K . Alluri Nitrogen Requirements in Conventional Tillage and No-Till Systems Investigations begun several years ago on the nitrogen requirement in tilled and no-till systems were continued in 1982. One trial, begun in 1978, is being carried out in the forest zone a t Ikenne on an Alfisol (Oxic Paleustalf) and another, begun in 1979, is being conducted in the derived savanna a t Ogbomosho on an Entisol (Psammentic Usthorthent). Both trials have a split-plot design with four OT I replications. 0 59 118 The 1982 maize crop yielded very poorly, particu- Fert~lizerr ate ( kg/ha) larly a t Ogbomosho, hecause of uneven rainfall Figure 17. Effects of' fertilizer rate and tillage method on (Table 11). There was no significant difference in yield of upland rice, lbadan and Onnr, Nigeria, 1982. yield resulting from tillage treatments a t Ikenne. Nor did the crop respond significantly to nitrogen The tubes also served as pots for growing the maize. treatment. At Ogbomosho, despite the extremely low N, P, K, Mg, Zn and plant ash were added to all the yields, the no-till treatment yielded less than the treatmcnts. tilled plots, as in previous years. At Ogbomosho With no lime mixing of the surface soil up to a continuous maize cropping caused a pronounced depth of 20 cm had no significant effect on the maize decline in soil nutrient status under both tillage plants (Figure 18). However, mixing the soil to a systems.-B.T. Kang and N.C. Navascro depth of 30 cm significantly depressed maize dry weight. Under no tillage maize dry yield increased Tillage and Residue Management significantly with application of 0.5 t of lime per Another experiment on the effects of tillage and hectare. As the depth of soil mixing was increased to residue management on an Alfisol was carried out a t 10 and 20 cm, the lime rates required to increase Mokwa in central Nigeria. Maize and sorghum were maize dry matter yield significantly also increased to the test crops. The trial had a split-plot design with 1.0 and 2.0 t /ha, respectively. Mixing the soil to a four replications. In the first year. only partial depth of 30 cm caused a significant response only to residue management treatments (including burning, the first increment of the 0.5 t of lime per hectare; mulching and removal of residue) were imposed further increases in lime rate did not improve maize because the land had been under a short grass fallow. growth. It appears that deep tillage in the highly acid Maize and sorghum growth was slightly depressed in the mulched plots, but there were no significant yield Table 11. Effect of tillage and nitrogen rate on maize differences. The tillage treatments (strip, con^ yield a t two locations in Nigeria, 1982 ventional, manual and no-tillage) had no significant N rate, Ikenne Ogbomosho effect on maize and sorghum yields. B.T. Kangand kg/ha Tilled No-till Mean Tilled No-till Mean E.N.O. Iwuafar kglha .\ Sc-rc~rnhousMe ethod For Studying t hc. 0 . . . . . . . . . . 2,915 3,147 3,031 122 48 85 I.:lTects of 'l'illagc. on Crop Pc~~.formanre 30 . . . . . . . . . . 3 ,456 3,519 3,487 756 380 568 6 0 . . . . . . . . . . 3,538 3,716 3,626 899 722 810 A screenhouse trial was conducted with a n acid 9 0 . . . . . . . . . . 3.656 4.017 3.836 1.149 967 1,058 Ultisol t o determine the eEect of mixing to various surface oil depths (one of the effects of tillage) on crop Mean. . . . . . . . 3,498 3,705 903 691 performance. Four soil mixing depths and four liming rates were compared, using a randomized complete LSD (5%) between: hlock design with four replications. Soil core samples Tillage means. . . . . . . . . . . . . . . . . . . . . . 606 205 from depths of 0 to 30 cm were collected from a Nratemeans . . . . . . . . . . . . . . . . . . . . . . 368 183 hush fallow plot a t IITA's Onne substation, using N rate with same till. trtmt.. . . . . . . . . . 521 259 N rate with diff.t rtmt. . . . . . . . . . . . . . . 752 306 aluminium tubes with an inner diameter of 12.5 cm. 136 Farming Systems Maize plant dry weight ( g/pot) two years just before planting the first season crop, followed by no-till as in the first treatment during the next three seasons; (5) planting every season with a chisel plzmter, using chisel depth of 20 cm: and (6) loo 7strip tillage 10 cm w ide and 13 cm deep in frnnt of the planter. The field used for the study had been cropped to maize, and weeds had been controlled chcmically for four years without any tillage. The lightweight farmobile was uscd for the first three years, and in the fourth large-scale, mcchanized no-tillage was employed. The design of thc experiment is a randomized complete block with six treatments replicated eight times. Maize (TZESK-W) was planted in the first season on 2 June 1982. Uniform fertilizer applications and herbicide treatments were used on all parts. Observations are being made on soil water infiltration (double-ring system), weekly soil moisture, yield, soil bulk density and soil chemical 1 .MM ixing, 0 to 10 cm properties. v--.-v Mixing, 0 to 20cm I In the paraplow t,re:itment, yields werc signifi- cantly higher t,han the others a t the 5% level (2,734 Mixing, 0 to30cm kg/ha for once a year and 2,661 kg for once every two 4.0 years), but treatments 1, 5 and 6 gave no significant o T differences. The hand-operated no-till treatment I I 0 0.5 1.0 2.0 yielded the least (1,998 kg/ha). The yield response appears to be related to the amount of soil dis- Lime rate (t /ha ) turhance causcd by the tillage method. The greater Figure 18. EtSect of' mixing depth in the surfare layer of ;I the disturhance, the higher the yield. Thus. the highly acid Ultisol on the lime response of rnaizc, Onnc, paraplow resulted in almost total soil loosening, and Nigeria, 1982. the chisel plantcr disturbed the soil a littlc more than strip tillage. The no-till system with tractor planter Ultisol may have undesirable chemical effects on the disturhed a very narrow line of soil, while the h;md- performance of maize. The higher acidity and A1 opcrated no-till planter caused the least disturbance. saturation of the subsoil may have been the principal The chisel setup for the chisel planter, which was cause of this phenomenon.-B.T. Kang and A. van made a t IITA, left a shallow trench hecause not all der Kruijs the soil chiseled aside fell b:ick int,o the cut. The Minimum Tillage Trials planter then planted the secds in this narrow trench, making i t difticult to control planting depth. Soil compaction becomes a serious problem on The low yields were most likely due to late kaolinitic soils under no-till systenis when tractors planting, :I relatively low ratc of N application and a r e used for plant ing and harvesting. While the choice of TZESR-W, a short duration variety of agronomists are studying crops and fallows that rather low yield potenti;il. As the experiment con- could alleviate soil compaction, the engineering tinues, we will determine whether the no-till hand section is conducting a long-term study to test treatment improves soil conditions and crop per- diWcrent conservation tillage practices for their formance when no tractor or equipment passes over ability t o avoid or alleviate compaction and allow the plots. The paraplow treatment resulted in good sustained crop production in a no-till system. production in the first crop, but its overall effects can The field experiment has six tillage treatments t.hat only be determined after the experiment has been cause minimum disturbance of t he surface soil: (1) a carried out over scveral seasons. C. Garmarl and continuous no-till system using a four-row no-till A S .R . J u o planter, a 10-m boom sprayer, a broadcast fertilizer applicator and a side-dress fertilizer applicator; (2) Ridged Seedbeds for Soybeans a continuous no-till system with hand-operated The soils in Benue State, a major soyhean growing equipment. including a rolling injection planter. a area in the northern savanna region of Nigeria, are hand-pulled 4-m pneumatic knapsack boom spriiycr loose and sandy Alfisols. In the growing season there and a manual fertilizer applicator; (3) tillage a t a (May to October). heavy rains often wash soybean depth of 25 cm with a Paraplow once a year just, seeds and seedlings away from the usually ridged hefore planting in the first season (the no-till system seedbeds ant1 cause the seedbeds to collapse. of thc first treatment is uscd in the second season);( 4) Sometimes farmers leave the prepared seedbeds to tillage a t a depth of 25 cm with a Paraplow oncc every settle during the first couple of rains before planting Farming Systems 137 soyheans. The erosion hazard in this area is high, and Experiments were carried out to determine the the rainfall, often torrential, occurs in a monomodal effects of ditferent methods of seedbed preparation on pattern. growth and yield of rice under upland and irrigated A simple experiment involving four methods of conditions. seedbed preparation was begun a t the Yandevstation of Ahmadu Bello University. Ridges, normally 24 cm Lowland bunded rice. The effect of three methods high, were flattened by levelling off the top to form of seedbed prepar:ltion and of two soil moisture beds 6 cm and 12 cm high. These were compared with regimes was investigated in an experiment with a Hat, harrowed plots and with undisturbed ridges split-plot design and three replications. The moisture 24 cm high. The treatments were arranged in a regimes were the main plots and methods of seedbed randomized complete block and replicated four preparation the subplots. The three methods were times. compaction with a roller, puddling involving both The data in Table 12 show the benefits of a firm dry and wet plowing, and no-tillage with chemical seedbed for soyheans in the loose sandy Alfisol that is weed control. The soil moisture regimes were rainfall characterist,ic of the Yandev area. The significant and irrigation to ensure continuous flooding. Root reduction in yield in the undisturbed ridges was due growth, grain yields and yield components were not to poor stands, but to a short drought spell after measured. planting in July, which very likely caused higher Upland rice. Experiments on upland rice were moisture stress on the young soybeans in the loose conducted a t ITTA's Onne substation. The effects of ridges. three tillage methods (compaction, no-tillage and conventional plowing) werc studied with and Tillage Systems and Mulch for Soybeans without mulch. The effects of these treatments on A tillage and mulch experiment with soybeans establishment, root growth, grain yield, and yield was begun in 1981 and repeated in 1982 on a field components were examined in a randomized block at Yandcv with a slope of 12%). The field was design with three replications. covered with a mixture of lmperata cylindrica and In the lowland bunded rice trial, which was carried St,ylosanthes. The legume covered about 20% of the out on a sandy coarse textured soil a t IITA, the rice total stand. This vegetation was killed with paraquat yield was higher on compacted soil than under other before seedbed preparation. methods of seedbed preparation (Tahle 13). Yield was The experiment compared various land prepara- also significantly greater from continuously flooded tion methods: standard beds 1 m wide along a slope than from rainfed plots. Compaction of these sandy (control), ridges along the slope, ridges across the soils decreases total porosit,y and macroporosity and slope and no-till. In the beds and ridges, tied and therefore decreases losses caused by water pcrcol- untied furrows were compared. Some of the no-till ation and Icaching of plant nutrients. Under rainfed treatments were mulched a t 4 t /ha, and others were conditions, however, compaction restricts root not. The experiment had a randomized complete growth and lowers yields, especially when soil block design with four replications. Soybean yields were generally low, even where Table 12. Effects of seedbed preparation method on estahlishment was 90 to loo'%,.G rowth was stunted ;is soybean yield, Yandev, Nigeria, 1982 a result of dwarfing, which we suspect was caused by Yield, I'lants virus and serious moisture stress, particularly in Plot preparation kg/ha pt,r m' 1981. The coefficient of variation in 1981 was 27'j/,,a nd Ridges undisturbed (control). 24 cm high 1,781b 20 in 1982, 42%,. The replanted, mulched plots (loo'%, Ridges flattened, 12 cm high . . . . . . . . . . . 1,963a h 20 establishment in 1982) outperformed the average by Ridges flattened, 6 crn high . . . . . . . . . . . . 2.022 a 20 53% because of the better moisture regime undcr "lnt, harrowed plots. . . . . . . . . . . . . . . . . . 2,169 a 18 organic cover. In 1981, when establishment in the C V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3 mulched plot was very poor, the mean yield in the no- ,,Yields lbllowerl hy the same letter within the culumn are not till plot was reduced about 33% below that of the signifirantly dilkrent. control, which is about the same as the reduction in soybean establishment (31%) in those plots.~-H.C. Tahle 13. Effect of seedbed preparation method on Ezumah and E.A. Kueneman yield of lowland rice under continuous floodinc. Onne. Nineria Tillage for Upland and Lowland Bunded Rice Rice yield, t/ha 1"irst scason Second season First season Although rice is rapidly gaining importance in the 'Srei~tment of 1981 of 1981 of' 1982 African diet, research information on the most Comoacted . . . 7.9 a 4 1 a 7.6 a desirable agronomic practices for different ecosys- Puddling.. . . . 6.6 b 3.5 h 5.1 b tems is rather scarce. Tillage requirements vary for No~tillare. . . 5.9 b 3.3 h 5 6 h upland and flood irrigated rice and differ according Note: Il'igures followed by (.he same letter arc stntistically to the physical and chemical properties of the soil. the same at the 5'+:> level of pl.ohability. 138 Farming Systems moisture is a limiting factor.-L. Ogunremi, R. La1 Table 15. Effect of tillage and compaction on maize, and 0. Babalola cowuea and soybean vield, IITA, 1982 Maize Cowpeas Soybeans Measuring Soil Compaction Compaction No- Conv. No- Conv. No- Conv. In gravelly, highly variable soils in the tropics, it level till till. till till. till till. is difficult to assess soil compaction by routinely tlha measurable soil properties (bulk density and Nopasses . . . . . . . . . . 5.9 6.9 1.3 1.3 1.0 1.9 penetrometer resistance, for example) that can be Twopasses . . . . . . . . . 3.8 4.6 1.0 0.9 0.7 1.4 related directly to crop responses such as root Fourpasses . . . . . . . . .2 .9 3.3 0.8 0.8 0.5 1.1 growth, water uptake and yield. A study was LSD (5%): conducted in cooperation with the Universities of Cornp. for same till. 1.1 0.3 0.2 Dar es Salaam and Copenhagen to develop more Cornn. fnr diff. till. 3.2 0.8 0 4 suitable criteria for measuring soil compaction in relation to plant response. The yield of crops was also affected by soil An experiment was begun in September that compaction treatments (Table 15). Cowpea yields related compaction to crop response at three levels of were 1.00, 0.72 and 0.61 t /ha under conventional soil compaction as main plots, t o two levels of tillage tillage and 1.00,0.82 and 0.66 t /ha under no-tillage for (no-tillage and conventional plowing) a s subplots, the control, two passes, and four passes of the roller, and to three crops (maize, cowpeas and soybeans) as respectively. This implies tha t at the same level of sub-subplots. All treatments were replicated three compaction cowpea yield was reduced more by the times. The three compaction levels were 0, 2 and 4 conventional than by the no-tillage system. The passes of a tractor-mounted, two-ton roller. All crops reductions in yields of maize and soybeans are also were seeded on 16 September 1982 and received a shown in Table 15.-B. Kayombo, R. La1 and H.E. uniform application of fertilizer (120 kg N, 26 kg P Jensen and 30 kg K/ha for maize and 30 kg N, 26 kg P and 30 kg K for legumes). Tillage and Soil Compaction The results so far indicate that the saturated hydraulic conductivity measured on cores using a Soil compaction is thought to be one of the problems constant head permeameter was influenced greatly of continuous, mechanized crop production and is by soil compaction and tillage methods. The effects of often observed to be very severe a t points where farm compaction were present to a depth of 10 cm in machinery turns. In the heavily weathered tropical plowed treatments and 15 to 20 cm in no-till soils, with their low-activity clays and low organic treatments. At each level of soil compaction, matter contents, compaction problems can become a saturated hydraulic conductivity in the no-till plots major obstacle to better agricultural production. A was generally higher than tha t in the plowed study was begun during October 1982 in cooperation treatments often by 50 to 150%)( Table 14). The high with the University of Gottingen, to quantify soil level of soil compaction decreased soybean emer- compaction caused by mechanized and manual gence by 10% and reduced the number of leaves and farming operations under no-tillage and conven- leaf area index by 45'%, under conventional tillage tional plowing systems. Soil compaction will first bc 34%, under no-till in cowpeas, and by 33 and 11%,i n characterized by evaluating soil physical properties soybeans. The plant height of the severely compacted (bulk density, porosity, pore size distribution, treatment was also reduced, by 21 and 9% in maize, penetration resistance, water transmission charac- 15 and 12%, in cowpeas, and 26 and 16'%, in soybeans teristics, etc.) and then related to root development under the conventional plowing and no~t i l lt reat- and proliferation and crop performance. ments, respectively. In the first experiment, root growth of maize (TZE) was investigated under no-tillage and conventional Table 14. Effect of soil compaction and tillage on plowing managed by manual and mechanized saturated hydraulic conductivity and operations. Manual operations included clearing, penetrometer resistance, IITA, 1982 seeding, spraying, fertilizer application and harvest- Soil Conventional tillage Na~tillage ing. In the mechanized system, all these operations were performed hy tractor driven implements. The depth No Two Four No Two Four cm passes passes passes passes passes passes experiment had a randomized split-plot design with four replications. Crop yields have not yet been cmlhr measured. 0 to 5 . . . . . . . 76.9 32.8 22.5 123.5 57.2 22.5 5 to The penetrometer resistance of plowed and no-till 10.. . . . . 66.4 37.2 35.6 121.2 62.4 30.9 10to15. . . . . . 44.0 89.4 45.1 109.4 99.0 57.5 soil, measured 10 weeks after seeding, seemed to 15 to 20. . . . . . 36.7 123.0 VL:L 102.9 124.1 74.0 indicate that the different tillage methods caused varying degrees of compaction. Plowed plots were Penetrometer more compacted than no-tillage plots, especially at resistance, kglcm . . . . . depths of 5 and 20 cm. As a result, the no-till plots had -~ 2.98 4.22 1.70 3.05 3,53 a higher root density in the surface 0-to-5-cm layer, Farming Systems 139 and the roots went down to 55 cm, compared with only 30 cm in plowed plots. Under the no-till system, the root density and penetrometer resistance varied according to whether manual or mechanized farm operation methods were used. There were more roots in the surface horizons of manually operated than in mechanized no-till treatments. This differential root distribution is related to the higher penetrometer resistance in t,he surface layer of mechanized than in manual treatments. H. Franzen, R. La1 and W.E hlers Land Clearing Saturated Hydraulic Flow in Soil After Land Clearing Tropical forests are being cleared by different methods for agricultural and industrial purposes. These methods greatly change the soil's physical 00 0.4 0.8 1.2 16 2.0 2.4 2 0 properties, particularly hulk density and water Pore volume retention and transmission properties. A study was Figure 19. Chloride breakthrough curve for undisturbed conducted to examine the influence of different land and repacked soil cores under saturated flow for manual and shear blade clearing treatments. Vp is the average pore clearing methods on water movement through dis- water velocity and C/Co is the ratio of influent concen~ turbed soil cores. Chloride, rather than a dye or trations, IITA, 1982. radioactive material. was used as a tracer to follow the depth of wetting front. Undisturbed soil cores were taken from the 0-to-20- ductivity and bulk density are also included. The cm layer of an Alfisolsandy clay loam(Egbeda series) dominant flow in all cases was through the larger pores, indicated by a pore volume of less than 1 to under forest and from plots cleared by manual, reach CIC, = 0.5. Saturated hydraulic conductivity traditional, tree pusher and shear blade methods. The plots had been under a no-till system for three was highest In soil under traditional farming, and mean bulk density was lowest. years. From these results i t appears that the method of The soil cores were first saturated with 0.01 N CaS04 solution, which was immediately replaced by land clearing has a considerable influence on water 0.1 N CaC12. At the same time, samples of leachate movement and saturated hydraulic conductivity in were collected for analysis. The saturated cores were cleared soils. These changes reflect the compaction weighed a t the end of a run for pore volume that occurs after forest vegetation is cleared from determination. These procedures were repeated for leached tropical soils. This compaction, which one reconstituted cores for which soil samples were might call structural collapse, changes pore size distribution considerably, decreasing the large and collected from depths of 0 to 5 , 5t o 10 and 10 to 15 cm in each plot. These were air dried and packed in increasing the small pores. As a result, hydraulic conductivity is seriously decreased with obvious columns in their natural order of occurrence. Stones were not discarded and helped to pack the soil in consequences for the ability of these soils to absorb columns at its field bulk density. The chloride breakthrough for undisturbed cores Table 16. Effect of land clearing on chloride leaching, collected from the manually cleared field show that saturated hydraulic conductivity and bulk the anion appeared in the affluent immediately after densitv. IITA. 1982 CaClz was applied to the soil surface (Figure 19). Saturated Mean This indicates relatively high flow through large, Land Pore vol- hydraulic bulk continuous soil pores. In the repacked columns, clearing ume to reach: conductivity, den~i ty ,~ method 0.5 C/COa 0.9 C/COa cm/hr g/cm3 chloride appeared a t a later stage, showing a relative lack of macropores in the soil samples. Forest The undisturbed cores from the shear blade treat- (control) 0.59 1.48 80.4 1.35 ment showed very similar flow characteristics, with Traditional farming 0.60 1.64 85.4 1.26 an initial slight delay in chloride recovery (Figure Manual 0.26 1.48 35.4 1.61 19). The displacement of the initial solution in the Shear blade 0.40 1.90 13.3 1.76 repacked column was nearly identical to that of the Tree pusher 0.40 1.84 20.8 1.70 repacked columns from the manual treatment. The results on chloride recovery in undisturbed Note: Far a leaching run, two undisturbed soil cores from a depth of0 to 20 cm were collected. soil cores from the other treatments are given in lRatio of eMuent to inHuent chloride concentration Table 16. Values for saturated hydraulic con- hStones were included. 140 Farming Systems rainfall without erosive runoff. B . S . Chuman and ments were made a t hourly intervals from 0800 to R. Lal 2200 hours a t depths of 5 and 10 cm. There were three tensiometers a t each depth, and the data presented Effects of Land C l e a r i n g on Hydrological are the average of three separate measurements. At 5 Properties cm no marked differences were found in diurnal soil A study was begun in 1979 to assess the effects of land moisture patterns between the different clearing and clearing methods and tillage systems on runoff and tillage treatments. There was a slight tendency for erosion, soil and microclimate, and crop yield. the soil in the traditional farming treatment to dry up Six land clearing methods and tillage systems were slower than in the other plots. This tendency was evaluated on individual watersheds of 3 to 4 ha each greatly magnified a t 10 cm, as shown in Figure 21. with two replications. The methods were traditional The traditional farming watershed still has a large bush clearing, manual clearing followed by oo- numbcr of trees (mainly oil palms). It is logical tillage, manual clearing followed by conventional tillage, shear blade followed by no-tillage, tree pusher/root rake followed by no-tillage and tree Tmd,l,~rnif orming pushertroot rake followed by conventional tillage. All conventionally tilled watersheds were terraced for protection against runoff and erosion. In the no- tillage watershed, the previous crop residues were 24 kept as a mulch, and herbicides were applied. 16 In 1982 the two conventionally tilled watersheds cleared with tree pusher/root rake attachments and 08 one of the manually cleared, unterraced watersheds were taken out of maize production and seeded to - 0 ' 0- 016 029 032 090 048 008 016 024 032 040 the leguminous cover crop Mucuna utilis for soil Volumefrc mo8sfuremtenr lcm3ic/cm31 restoration. Accelerated soil erosion in these treat- Figure 20. pF curves determined in situ and in the ments had resulted in rapid soil degradation and lahoratory for two methods of land development. IITA, caused severe yield reductions. All the remaining 1982. watersheds were sown t o a maize/cowpea rot,ation. Volurnetr~c water content l c m 3 / c d I Soi l hydrological propert ies . The soil moisture retention characteristics, determined by tensio- metric measurements and gravimetric moisture determinations, were significantly affected by the methods of land clearing and soil management after clearing. The data indicate tha t the soil i n the traditional farming plot retained high moisture a t low suctions and less moisture a t high suctions (Figure 20). The reverse was the case with soil from a plot cleared by tree pusherjroot rake attachments and conventionally tilled during three successive years of cropping. For example, moisture content a t a depth of 0 to 10 was 48, 40, 14 and 13% by volume for pF values of 0, 1, 3 and 4, respectively, in the traditionally cleared plot, compared to 40,38,20 and 19y0 in the tree pusher/root rake plot. These results indicate a predominance of macro- pores i n the traditional farming plots and of micropores in the mechanically cleared and con- ventionally tilled treatment. The total porosity was also 8% more in the traditional than in the conventional tillage treatmeht. For the traditional farming treatment, soil moisture characteristics determined in the field agreed with laboratory results. Rut field determined moisture contents at, any suction were generally lower than the laboratory values for the tree pusherlroot rake treatment (Figure 30). Figure 21. Diurnal fluctuations in volumetric soil moisture D i u r n a l c h a n g e s i n soi l m o i s t u r e profile. content for different mrthods of land clearing and tillage Tensiometric and gravimetric soil moisture measure- systems, JITA, 1982. Ii7armingS ystems 141 to conclude that shading, low soil and ambient Multiple Cropping and Rotations temperature, the insulating effect of mulch and vegetative cover, low runoff and evaporation losses, MaizeICassava Intercropping and the high soil moisture retention capacity of the The effects of maize and cassava architecture on the soil in traditional farming plots are responsible for microenvironment of maize and cassava grown in this favorable moisture condition. association were monitored by TITA's farming Four-hourly changes in the soil moisture profile systems agroclimat~ologist. Since moisture and (shown in Figure 21) varied significantly according insolation limit crop production in the southern to the method of land clearing and tillage. As parts of West Africa, plant modifications that make indicated by the i r low soil moisture suct ion moisture and sunlight more available should (discussed above), traditional t reatments were improve the yield of component crops in mixed observed to have high soil moisture content. The cropping systems, particularly those with a multi- increase in evaporative demand during the day story canopy structure. To determine the extent to caused :I progressive decline in soil moisture content which this is so, maize and cassava varieties with in thc upper 5 cm, although the most significant the following plant architectures were studied: a decrease was observed in t h e 0-to-3-cm layer. spreading cassava variety (TMS 30572) whose leaf Regardless of the land clearing and tillage methods, area indices (total plant leaf area divided by the land the lowest soil moisture content in the surface layer area i t occupies) a t Ibadan a t two, four, six and eight was observed from 1200 to 1600 hours. Measurements months were 0.3, 2.0, 6.5 and 5.0, respectively, and a a t 2200, and on the following day a t 0800 hours relatively erect type (TMS 30001) with leaf arca showed that the soil moisture content of the surface indices of 0.25, 1.50, 3.30 and 2.10 a t the same ages. layers was higher than a t 1600 hours (Figure 21). This The leaf area indices of TMS 30572 a t those ages increase in soil moisture content can be attributed to were 20, 33, 97 and 138% higher than those of 30001 the temperature reversal during the night and (Figure 22). subsequent dew and to the condensation of soil water Two varieties of maize were used, a spreading type vapor within the upper soil layers, probably a t the (TZPB) and a relatively erect type (Kewesoke) with expense of soil moisture in the 5-to-8-cm layer. The narrower leaves. The leaf area index of TZPB eight agronomic significance of this phenomenon, if i t weeks after planting was 5.2, which indicated that it occurs widely, needs t o he determined. had a 27%) higher leaf area than Kewesoke, whose Regardless of the method of land clearing, no- leaf area index a t the same age was 4.1. The two tillage outyielded the conventional tillage system cassava varieties and two maize varieties were (3.3 t /ha compared to 2.4 t). Shear blade clearing established in a split-plot design with two maize followed by no-till led to better crop performance populations (30,000 and 60,000) and one cassava than did other methods of land clearing. Maize yield population (10,000). The cassava varieties were the from the manually cleared no-tillage treatment main plots. equalled that from the shear blade treatment for the As reported in the IITA Annual Report for 1981, same time of clearing. One of the reasons for the no pronounced differences in soil moisture were stable and high yields of the shear blade treatments is observed under the different crop combinations, that less water runoff and soil erosion take place in although the light transmitted through the upper those treatments and the decomposing root channels canopy of Kewesoke to the interplanted cassava was of the perennial crops provide avenues through 5 to lo'% higher than the amount transmitted which maize roots can penetrate subsoil horizons and through TZPB. With a n increase in maize population reach moisture and nutrient reserves.-0. Opara- fkom 30,000 t,o 60,00OpIants/ha, the percentage of Nadi and R. La1 light transmitted decreased by 15% for Kewesoke and 9%, for TZPR. Cropping Systems and Cassava type had no significant effect on maize yield. TZPR, which has superior yielding ability, Management yielded 49% more than Kewesoke. Slight increases in the yield of each maize variety were obtained by In 1982 increased attention was given t o cropping doubling the maize populations (30,000 to 60.000). systems and management. We expect to give this The relative yields of intercropped maize, based on subject even more emphasis in the future as we monocrop performance, ranged from 80 to 99% for reorient the large-scale experiment on the West Bank TZPR and 84 to 102%, for Kewesoke. Since these a t ITTA. This study was originally designed to deter- differences are not significant. i t can he concluded mine the effects of various land clearing and manage- tha t the cassava had no effect on maize yield, ment practices on erosion, soil-water relations, soil regardless of the cassava or maize architecture. degradation and crop performance. Beginning in Increasing maize populations to 60,000 plantslha 1983 the experiment will center on a number of can cause significant differences in cassava root cropping patterns, involving a wide variety of crops, yields in a cassava/maize intercrop. Cassava inter- and their effects on soil productivity, runoff and cropped with the spreading maize variety, TZPB, erosion, and farm management economics. especially a t a high population (60,000 plantslha), 142 Farming Systems Leaf area tndex ( mZ/m2 I Monitoring of the microenvironment showed that I melon and okra did not significantly reduce the photosynthetically active radiation received by cassava, whereas in the cassava/maize intercrop, cassava received significantly less light. Cassava yields were significantly reduced by maize and by three combinations of cassava, melon and okra. The reduction in cassava yield caused by including maize in the intercrop was about the same as that resulting from okra and melon combined (Table 18). These results agree with those of the maize/- cassava experiment reported above in that a sig- nificantly lower amount of light was transmitted to maize by cassava between 4 and 10 weeks of growth. Fresh root yield of cassava was also significantly decreased. The magnitude of light received does not explain the significant reduction in cassava root yield in the cassava/okra/meloni ntercrop (Table 18). The results of this experiment and of the one on cassava/maize intercropping clearly show that cassava does not reduce maize yield when the two are intercropped (Tables 17 and 18). Maize with cassava sometimes yields more or as much as maize alone. This is due in part to their wide differences in time of maturity (more than a year for cassava and 90 to 120 days for maize) and to the fact that maize and cassava do not compete during their periods of optimum vegetative development (Figure 22). But the high maize yields also suggest that it may bederiving some I I I I I I I benefit from the intercropping with cassava. H.C. 0 2 3 4 5 6 7 8 9 Ezumah and T.L.L awson Months after planting Figure 22. Effect of age on leaf area indices of different Mechanization in MaizeICassava varieties of cassava and maize grown in a mixed cropping Intercropping system, IITA, 1982. A major consideration in mechanizing maize/cassava intercropping is the consequences of damage done by yielded less than cassava with relatively erect maize maize harvesting machines to cassava. To test the (Table 17). Higher light reception is therefore reaction of cassava to this damage, the damage associated with higher root yield by cassava inter- anticipated was simulated by cutting back the cropped with maize. The amount of light received and cassava stem to various h e i g h t s 4 (control), 40, 60 the resulting differences in root yields of a given and 80 cm-at the time of maize harvest. Thr cassava variety are affected by maize architecture. experimental design was a randomized complete Thus, the 5 to 105: higher light transmission to block with four replications. cassava by Kewesoke as reportedin 1981r esultedin a The growth parameters (plant height, leaf index, mean increase of 32U/, in root yield of TMS 30572. branching and stem diameter) measured a t harvest Experiments were begun in 1981 to determine the showed no significant differences between treat- effects on the performance of maize and cassava of ments, indicating that the cassava was able to including Egusi melon and okra in maize/cassava regenerate its aboveground parts between maize and intercropping systems. Changes in microenviron- cassava harvest. However, the plants recovered only mental factors a t specific growth stages were a t the expense of tuber development. The number monitored in the field and greenhouse. The layout of tubers per plant and yields per hectare were had a split-block factorial design with three significantly reduced by all cuttings (Table 19). In a replications. Two cassava cultivars with different trial carried out last year, cutting had no significant growth habits and yield potentials (TMS 30572 and effect on yield. Thus, the extent to which cutting TMS 30001) made up the main plot treatments, while influences plant recovery and yield may depend on the intercropping systems formed the subplots. The prevailing climatic conditions. Because there were plant population of the cassava was 10,000 plantslha no significant differences between cutting heights, in 1981 and 1982, that of the maize (TZPB) 20,000 it appears that machines causing similar damage plants in both years, that of the okra (V45) also 20,000 within the height range used should he acceptable if plants, and that of the melon 20,000 plants in 1981a nd the increased efiiciency outweighs the cassava yield 10,000 in 1982. loss.-G.F. Wilson and P.S.O. Okoli Farming Systems 143 Table 17. Effects of cassava and maize architecture on yield, IITA, 1982 Cassava variety TMS 30572 Cassava variety TMS 30001 Cassava Maize Total Cassava Maize Total yield, yield, relative yield, yield, relative Maize variety k / h a kg/ha yield kg/ha kg/ha yield 1A-'.7 PR., 30,000 plants/ha . . . . . . . . . 15,700 3,054 1.6" 12,650 3,461 1.65 60,000 plantslha. . . . . . . . . . 10,900 3,793 1.59 8,650 3,589 1.45 Kewesoke 30,000plantsjha.. . . . . . . . . 19,020 2,034 1.84 13,340 2,170 1.63 60,000plants/ha . . . . . . . . . . 14,510 2,628 1.82 11,920 2,239 1.57 Means . . . . . . . . . . . . . . . . . . . . 15,025 2,877 11,640 2,865 Monocrop cassava . . . . . . . . . 18,030 1 O. O 16,910 1O . O Monr~cropm aize (TZPB) . . . . 3,838 Monocrop maize (Kewesokc) 2,580 LSD ( S T , ) . . Maize varlet~es. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 592 (s) Cassnva varieties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,920 (ns) Maize pop. on maize yield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376" Maize pop. on cassava yield (same var.) . . . . . . . . . . . . . . . . . . . . . . . . 3.791 (s) USig~~ificaonly with TMS 30672 Effect of Moisture Cycle on Cassava permit harvesting a t the end of an annual moisture A previous study on declining yields of cassava with cycle, leaving thc land free for use a t the onset of the increased severity (duration and intensity) of the dry next cycle. T . L . L awson season hefore harvest (IITA, Annual Report for 1980) indicated that the longer the moisture cycle, in Maize/Cowpea Intercropping proportion to the growing season (from planting to The varying growth habits of cowpea varieties affect harvest), the higher the yield. The results also their usefulness in mixed cropping systems. Cowpeas indicated that cassava is similar to other crops in are usually the minor crop in mixtures with other that it requires favorable moisture throughout its crops, especially in Africa. Research was begun in growing cycle to reach maximum yields. 1981 on maize/cowpea and cassava/cowpea systems To confirm these deductions, differential irri- to evaluate the performance of these mixtures under gation, simulating moisture cycles of different duration, was applied to two cassava varieties (TMS Table 18. Yield of cassava and maize intercropped 30555 and TMS 30572). Treatments were applied to with okra and melon. IITA. 1982 whole blocks, with each cassava plot replicated three Cassava times within each block. Planting was done a t the fresh root Maize beginning of the 1981 cropping season (mid-April). Crop mixture yield, tjha Crop mixture yield, t/ha Three moistureregimes were imposed after theend of Cassava only. . . . 25.46 a Maize only. . . . . . . 2.96 b the rains on 31 October and two hlanket irrigations of Cassavalmaize . . 19.40 b Maize/cassava . . . 3.17 ab all plots were done on 20 November and 1 December. Cassava/okra . . . 26.63 a Maize/okra . . . . . . 3.07 b In treatment 2 no morc irrigation was applied. Cassava/melon . . 22.03 ab Maize/melon . . . . . 2.96 b Treatment 2 received additional weekly irrigation Cassava/okra/ Maize/okra/ throug- h 31 Uecemher, and the additional irrigation melon. . . . . . . . 18.55 b melon.. . . . . . . . 3.43a in treatment 3 continued March- 1982. Note: Means in the same co lumf~ol lowed by t h e letter are The crops were sampled for fresh root yield on not significantlyd ifferent at the 5%, level of probability 2 December (before the additional irrigation treat- ments) and harvested in mid-March 1982. Table 19. Effect of cutting height on cassava yield, The results for both varieties show that there was IITA. 1982 no significant difference in yield per plant before these treatments were imposed (Figure 23). At final Number Tuber yield of tubers dry weight, harvest, however, yield differences between treat- Cutting height, cm per plant t/ha ments 1 and 3 were significant, and the difference in mean yield per plant was highly significant. Control . . . . . . . . . . . . . . . . . . . . 9.7 17.6 80 . . . . . . . . . . . . . . . . . . . . . . . . . 7.3 14.2 These results confirm that the productive potential 60 . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 13.1 of these cassava varieties declines in increasingly 40 . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 13.1 dry areas. They also indicate the need for varieties with growth cycles that are more compatible with LSD (5%). . . . . . . . . . . . . . . . . . . 1.7 2.2 seasonal moisture cycles. Such varieties would C.V.,,% . . . . . . . . . . . . . . . . . . . . 13.2 9.7 144 Farming Systems Meon yield per Iil0"f 1191 . thinned to 60,000; IT 823.60 was left unthinned. Fertilizer (15-15.15) was applied a t a rate of 200 kg/ha. Insects were controlled by spraying a t 22 and 40 days after planting. Harvest,ing frequency was based on the maturity of each variety. With neither of' the cowpea varieties in any of t he cropping patterns and seasons, was the yield reduction of intercropped maize below that of monocropped maize (Table 20). Maize yields were higher than normally expected for TZPB in the long, first season but normal in the short, second season. Since yield differences resulting from diEerences in planting patterns were not significant, planting patterns should probably be selected on the hasis of factors other than yield. Monocrop cowpea yields were significantly higher than mixed crop yields (Table 20). Differences in planting pattern caused no differences in cowpea Figure 23. Effect of the duration of a favorable moisture yield. Since cowpeas do not reduce maize yield, it cycle on cassava yield, IITA, 1982. is highly advantageous to intercrop maize with cowpeas, particularly during the second season, different conditions. In 1982 a n early maturing when the yield advantage. expressed as the total cowpea variety developed by IITA scientists was relative yield, could be as high as 25%, compared used in mixed cropping experiments. with about 4% during the first season. A 60-day erect cowpea (IT 82E-60) and a standard As expected, cowpeas matured faster during the variety (VITA-5) were grown in four planting drier second season than in the first (Figure 24). patterns with a late (TZPB) and an early (TZESR) During both seasons, i t took only two harvests to maize variety. The pat terns were (1) cowpeas pick over 90% of the total yield of the early cowpea arranged in alternate rows with maize; (2) two rows variety, IT 823-60, regardless of the planting pattern. of cowpeas, 40 cm apart, planted between adjacent In contrast, three or four harvests were required for rows of maize; (3) cowpeas and maize in the same VITA-5 during the first season, especially in the row; and (4) cowpeas and maize in the same row but monocrop and double-row planting p a t t e r n s . H.C. with a second crow of cowueas relav wlanted with Ezumah, B.R. Singh and S.R. Singh " . maize soon after harvest of the first crop. The maize rows were 1 m apart, and within-row spacing was Cassava Canopy Structure in 25 cm. A fift,h pattern, the control, was monocropped Intercropping maize also planted a t spacing of 100 cm x 25 cm. The Cassava is a maill component of mixed cropping seeding rate of cowpeas was 120,000/ha a t planting. systems in many parts of the humid tropics. Previous VITA-5, which has a spreading growth habit, was studies have shown that competition for light is a Table 20. Effects of planting pattern on yield of maize and cowpeas, IITA, 1982 First season (April planting) Second season (August planting) Maize Cowpea Combined Total Maize Cowpca Combined Tot,al yield, yield, yield, relative yield, yield, yield, relative Planting pattern kg/ha kg/ha kg/ha yield kg/ha kg/ha kg/ha yirld TZPB and VITA-5 TZESR and VITA-5 Maizeonly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 ,420 6,420 1.00 2,430 2,450 1.00 Cowpeas/maize in alternate rows . . . . . . . . . . . . . 6,060 51 7 6,577 1.46 2,270 6% 2,960 1.62 Double-row cowpeas between two maize raws . . 6,160 487 6,647 1.45 2,280 860 3,140 1.80 Cowpeas in same row as maize . . . . . . . . . . . . . . . 5,590 614 6,204 1.49 1,190 7 50 2,740 1.57 Cowpeas and maize in same rowlcowpea relay. . 5,510 551 6,061 1.42 2,100 840 2,940 1.70 Cowpcas only. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 992 992 1,000 1,000 TZPB and IT 823.60 TZESR and IT 823-60 Maize only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6,420 6,420 1.00 2,430 2,430 1.00 Cowpeas/maize in nlternatc rows . . . . . . . . . . . . .6 ,120 510 6,630 1.35 2,370 590 2,960 1.52 Douhle~rowc owpens between two maize rows . . 5,880 640 6,520 1.43 1,930 880 2,810 1.59 Cowpeas in same row as maize . . . . . . . . . . . . . . . 5,640 680 6,320 1.42 1,840 780 2,620 1.47 Cowpeas and maize in same row/cowpea relay. . 5,550 680 6,230 1.40 1,850 720 2,570 1.41 Cowpeas only. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,260 1.260 1,100 1.100 I,SD (5%) varietv x planting uattcrn . . . . . . . . . 900 223 206 830 200 154 Farming Systems 145 major factor in thc relative productivity of the Cowpea yield ( kg/ha) component crops in the mixtures (IITA, Annual Reports for 1980 and 1981). In one study comparing the microclimate of the canopy of cassava having strap leaves with that of cassava having normal leaves (TMS 30001), it was found that there may he some advantage to growing the former in association with low growing crops. In a followup experiment, cowpeas (TVx 3236) were interplanted within these two types of cassava to determine the response of cowpeas to ditferences in microclimate, particularly light, under the cassava canopies, the possible effects of these differences on cowpea insect pests, particularly pod hugs, and the implications of these differences in pest control. The mixed crop plots were laid out in a randomized complete hlock with three replications. The mono- '# 2nd season cropped cowpea control plots were laid out in a Monocrop separate hlock. Half of each plot was sprayed for major cowpea pests twice during the growing season with Decis a t 15 to 20 g a.i./ha and Thiodan a t 500 g a.i./ha. Thrips and Maruca were assessed hased on VITA-5 flower sampling, and pod sucking bugs were counted visually. The differences in light transmission through the cassava canopies were comparable to those pre- 0 I 2 3 4 1 2 3 viously observed. Rut the trend was somewhat Number of harvests different because of less favorable moisture condi- 69-1 st season harvest-94 56 70 tions in 1982 and a consequent poorer rate of growth. 70-2nd season harvest-84 58 66 Cowpeas in the strap leaf cassava yielded up to 92%, Number of days of the monocrop yield; the corresponding yield with normal leaf cassava was only 40% of the control Figure 24. Effect of planting pattern on yield and rat.e of because less light was transmitted to the intercrop grain maturity of cowpeas, IITA, 1982. (Figure 25). Second season cowpea yields were very low in both mixtures (14 and 5'% of the control) of mixed crop production systems. T.L. Lawson and mainly because of excessive shading (Figure 26). L.E.N. Jackai For the sprayed cowpeas, the relationship between yield and light incident on the crop is expressed as follows: Y = 1,043/11 + Weed Management 17.892e (0.11343x - 0.00237 x')] (R =0.96). Air temperatures within the strap leaf canopy near Chemical Control of Fallow Vegetation the top of the cowpeas were close to those of the A study was begun to evaluate a range of herbicides monocrop cowpeas and up to 20°C higher than the and herbicide mixtures for control of perennial values observed in the canopy of TMS 30001. The weeds after hush fallow clearing and to identify reverse was true of the relative humidity. The soil preplant herbicides that do not create residue moisture was generally higher under the normal leaf problems in the crops. Thc experiments were con- cassava/cowpea combination during the early phases ducted a t four locations, representing: (1) typical of growth. These results agree with those previously woody perennial bush regrowth, (2) the mixed obtained i n pure stands of the two cassava types perennial grasses and broadleaves of the tropical (IITA, Annual Report for 1981). rain forest and (3) the mixed perennials of the The merits of the strap leaf cassava in inter- savanna. cropping systems are evident from these results. As One experiment was carried out at llTA on a site in previous studies, rapid decline in the yield of that had been under no-tillage farming for three interplanted crops is closely related to a narrow drop years. After that cropping period, the residualfallow in light intercepted from about 75 to 60% of the vegetation consisted of woody perennials such as prevailing global radiation. Given the differences Alchornia laxiflora, Ficus exasperata, Combreturn in the light transmission characteristics of the hispidum, Hippocratea pallens, Newbouldia leauis two cassava canopies, the potential advantage of and Albizia spp. Control of these perennial weeds incorporating the strap leaf character into some was assessed qualitatively by visual ratings and popular varieties is obvious. This type of cassava quantitatively from samples taken at the beginning offersa wide range of possibilities in the development of the study and after maize harvest from fixed 146 Farming Systems quadrats along a transect in each plot. The design treatment in all plots t o kill new seedling weeds was a randomized complete block with five rep- before planting maize. Annual weeds were controlled lications. The preplant herbicides were applied so by a preemergence application of a tank mixture of that maize could be planted within two weeks after metolachlor plus pendimethalin (2.0 + 1.5 kg/ha). treatment, but planting was delayed over two weeks Soil samples were taken a t intervals to assess the by a sudden dry spell. A supplemental paraquat spray residual activity of the preplant herbicides. These was apphed a t the rate of 0.5 kg/ha as a blanket samples were used in hioassays involving maize, cowpeas and rice as test crops. Seed yleld ( kg/ha) Data on the effects of the preplant herbicides are 1,200 shown in Table 21. Glyphosate (2.0 kg/ha) applied sequentially with 2,4-D (2.0 kg/ha) gave the hest control of al l perennial weeds and performed significantly better than when the two herbicides were applied as a tank mixture. Treatments that killed less than KO')/, of the perennial weeds (based on actual stand count) were considered ineffective in reducing the regrowth of woody perennials. Although crops can be planted immediately in fallows sprayed with glyphosate or paraquat, other preplant herbicides such as amitrole and tank mixtures such as glyphosate plus 2,4-D or dicamba plus 2,4-D proved to be toxic to cowpeas and rice planted within the first week after applying the preplant herbicides. However, residues of these herbicides disappeared from the soil within four weeks a t this site. The second experiment a t IITA was located in two- year bush regrowth that had been slashed twice. The vegetation consisted of perennial broadleaves and grasses. The dominant broadleaves were Eupatorium odoratum, Deinbolliapinnata, Combretum hispidum, Alchornia laxiflora and F icw exasperata. The main Percentage of perennial grass weed was Panicum maximum. The light transmitted to cowpeos design and methodology of the experiment were Figure 25. Relation between cowpea yield and percent global radiation incident on the crop through a cassava canopy, IITA, first season, 1982. cowpeas. A preemergence spray of pendimethalin Percentage of global rodlotlon oncldent on cowpeas (2.0 kg/ha) was applied to cont,rol Rottboellia Table 21. Effect of preplant herbicides on woody perennials in a no-till system, IITA, 1982 Percentage of Maize No. of Maize Treatment and perennials popu- cobs yield, rate, kg a.i./haa killed lation per ha kg/ha Glyphosate (3.6) . . . . . . . . . . . . 79 25,100 27,900 2.9 Glyphosate (2.0) . . . . . . . . . . . . 76 25,000 27,900 3.0 Glyphosate (2.0) followed hy 2.4-D (2.0). . . . . . . . . . . . . 84 24,700 25,800 2.9 Glyphosate (2.0) + 2,4-D (2.0). . . . . . . . . . . . . . . . 46 23,800 26,000 2.8 Glyphosate (2.0) + 2, 4-D (1.0). . . . . . . . . . . . . . . . 59 29,400 29,900 3.1 Amitrole (4.0). . . . . . . . . . . . . . . 40 21.800 22.100 2.5 Dicamha (1.5) + 2.4-D (.2 .0.) . . . Slashing.. . . . . . . . . . . . . . . . . . 33 21,900 21;500 2.4 Paraquat (1.0) . . . . . . . . . . . . . . 33 26,400 27,800 3.0 0 Paraquat (1.0) followed 9 1 1 13 15 17 19 21 23 25 27 29 31 33 by slashingb.. . . . . . . . . . . . . 46 26,100 29,200 3.1 Weeks after planllng carsovo Figure 26. Percent global radiation incident on mono- LSD (5%) . . . . . . . . . . . . . . . . . . 26 6.500 5.800 0.5 cropped cowpeas and cowpeas mixed with strap leaf (TMS *All herbicide treatments were preplant foliar sprays. X) and normal leaf (TMS 30001) cassava, IITA, 1982. bSlashingw as done two wccks after the paraquat treatment. Farming Systems 147 Table 22. Effect of preplant herbicides on bush regrowth in a slashed two-year fallow, IITA, 1982 I'ercentage Weed control ratinga of woody Cowpea Maize Alchurnia Combre- Eupa- Hippo- Panicum perennials yield, yield. Treatment and rate, kg a.i./ha laxiflora tum torium Ficus cratea maximum killed kg/ha t/ha Glyphosate (3.6). . . . . . . . . . . . . . . . . . . . . . . 63 50 80 - 40 80 51 788 3.78 Glyphosate (2.0). . . . . . . . . . . . . . . . . . . . . . . 60 57 74 20 37 85 50 688 4.36 Glyphosate (2.0) + 2.4-D amine (1.0). . . . . 63 83 79 40 37 80 46 870 4.57 Glyphosate (1.5) + 2. 4-D amine (1.0). . . . . 55 78 69 30 35 70 47 691 3.53 Glyphosate (0.7) + 2, 4-D amine (1.0). . . . 45 67 69 47 10 53 36 599 2.06 Glyphonate (1.5) + fosamine (6.0). . . . . . . . 45 10 49 55 20 80 45 551 3.53 Glyphosate (1.5) + dicamba (1.5) . . . . . . . . 45 75 68 ~- 25 80 42 703 3.81 Fluazifop-butyl (2.0) + 2, 4-D ester (2.0) . . 30 80 73 60 30 73 49 739 3.63 Fluazifoy-butyl(1.5) + 2.4-D ester (1.0) . . 36 80 64 20 33 ti0 37 443 2.84 Fluazifop-hutyl(1.5)+ amitrole (2.0). . . . . 45 50 53 45 40 - 35 466 4.26 Fluazifop-butyl(1.5) + fosamine (6.0) . . . . 20 10 37 30 13 67 38 814 3.81 Amitrole (4.0). . . . . . . . . . . . . . . . . . . . . . . . . 35 35 39 3 0 40 30 66 560 3.88 2,4-D amine (2.0). . . . . . . . . . . . . . . . . . . . . . 43 67 68 60 20 0 43 685 3.50 Dicamba (3.0). . . . . . . . . . . . . . . . . . . . . . . . . 40 50 61 - 48 -- 66 491 4.03 Picloram (0.1) + 2.4-D (0.5). . . . . . . . . . . . . 40 50 63 20 20 0 54 425 4.30 Dicamba (1.5) + MCPA (2.0). . . . . . . . . . . . 55 82 81 - 43 - 40 738 2.92 Dicamba (1.5) + 2, 4-D (2.0) . . . . . . . . . . . . . 60 85 86 - 0 48 568 3.44 Dalapon (4.0) + 2, 4-D (2.0) . . . . . . . . . . . . . 25 67 75 25 20 40 24 847 3.12 Slashing at planting. . . . . . . . . . . . . . . . . . . 5 50 8 0 0 33 722 3.00 Paraquat (1.0) . . . . . . . . . . . . . . . . . . . . . . . . 20 0 16 0 30 44 337 2.30 LSD (,ST,) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348 1.83 aWeed control was rated on a 0 to 100 scale, where 0 = no control and 100 = complete control. exaltata, which was conlmon a t this site. Other minalia glauscens, Isoberlinia, Cassia and Acacia annual weeds were hand pulled from the plots a t five spp. Promising herhicides and mixtures were gly- weeks after treatment. phosate plus 2,4-D, dicamha or fosamine; dalapon The results of this test showed that none of the plus 2,4-D; and flumifop-butyl plus fosamine. How- herhicides gave satisfactory control of all broad- ever, the last mixture persisted a t toxic levels for up leaves and grassy weeds (Table 22). Treatments that to four weeks after treatment. Table 24 shows the showed a wide spectrum of activity and merit further toxicity pattern of some preplant herbicides used in investigation are glyphosate plus dicamba and the Ikenne and Ilorin experiments. Many of the glyphosate and 2,4-D, applied either sequentially or mixtures used a t both sites were toxic to cowpeas and as mixtures. Some herbicide mixtures, such as rice planted in soils sampled immediately and a t two fluazifop-hutyl plus 2,4-D or fosamine, gave promis- weeks after treatment. When maize was used as the ing control of perennial weeds, but they tended to test crop. some herbicides, such as fluazifopbutyl plus persist far too long and could pose phytotoxic fosamine, were phytotoxic even when soils were prohlems to commonly grown food crops. Generally, sampled a t four weeks after treatment. the ester formulation of 2,4-D was more effective on a In future research we will define specific rates and cross section of woody perennials with pubescent formulations for tank mixtures and closely monitor (Combretum spp.) and nonpubescent (Alchornia the aftereffects to ensure that productsrecommended laxiflora) leaves. Similar results were obtained in a not only control the preplant vegetation, but are two-year fallow of mixed perennial grasses and also economical and safe t o both the crops and broadleaves a t Ikenne, which is more representative ecosystems. of the subhumid forested tropics. Table 23 shows the results of a similar study conducted a t Ilorin in the southern Guinea savanna Performance of Preemergence Herbicides region of Nigeria. A t tha t location, the major Previous studies have shown that although many weeds are tall, tussocky perennial grasses such as preemergence herbicides give good weed control Andropogon gayanus, A. tectorum, Hyparrhenia after conventional tillage they result in poor control inuolucrata, H. ruffa and Pennisetum spp. These are of annual weeds in no-tillage systems, even with a generally burned during the dry season but survive good kill of the preplant fallow vegetation. Pre- to produce new flushes of growth a t t he onset of the liminary work showed that mulches intercept some rainy season. Another commonly occurring peren- of the atrazine and metolachlor applied broadcast to nial grass is Imperata cylindrica. The regrowth of the mulch and could reduce their effectiveness. The woody perennials is from such fire resistant species objective of these studies was to test the efficacy of as Daniellia oliueri, Butryospermum parkii, Ter- some preemergence herbicides and their persistence 150 Farming Systems each in comhination with either metolachlor or and in combination with either metolachlor or pendimethalin, provided good control of all weeds up pendimethalin provided satisfactory weed control. to about five weeks after treatment. After that period Bifenox and butachlor gave good control but caused Vernonia pauciflora, a late appearing weed, became heavy stand losses. Oxyfluorfen gave good control predominant, and only chloramben plus metolachlor initially, but by five weeks after treatment, the plot gave satisfactory control. Oxyfluorfen plus either was reinfested. Cowpeas usually recovered from the metolachlor or pendimethalin caused severe cowpea initial injury caused hy this herbicide. None of the injury and stand loss, resulting in significant yield t reatments in th is t r ia l controlled Euphorhia reductions. heterophylla. Average weed growth in the untreated weedy plots The results indicate that preemergence appli- a t IITA was 2,643 kg/ha (Table 30). Chloramben alone cations must be supplemented later by other methods of weed control t o remove early escapes. I n future Table 27. Effect of cultivar, interrow spacing and trials we will test the effectiveness of following a weed control on rice yield in hydromorphic preemergence application with an interrow directed soil, IITA, 1982 spray of suitable herbicides. ITA ADNY Spacing x OS6 118 11 weeding Spacing Mulches for Weed Control 15.cm spacing tlha Appropriate management of ground covers can be Weed free . . . :1.4 3.3 3.9 3.5 effective in soil conservation and weed control, and Two hoe their organic mulches, dead or alive, can bring about weedings . . . . 2.8 2.7 3.1 2.9 3.0 long-term soil improvement and suppress weeds. One hoe Studies a t IITA have shown that Mucuna utilis forms weeding. . . . . 2.7 2.3 3 1 2.7 a good mulch for crop production. A study was 3O~cms pacing W ~ e dfr ee . . . 4.0 carried out t o test weed control with a residual 3 3 3.9 3.7 Two hoe mucuna mulch. The plot had been in mucuna fallow wecdinrs . . . . 2.7 3.9 3.7 3.4 3.3 during 1981. The volunteer mucuna seedlings from One hoe seeds buried in the thick mulch were killed first with weedine . . . . 2.7 2.7 3.1 2.8 a hroadcast application of paraquat (0.5 kg/ha). The 45-cm sparing design was a randomized complete block, with six Weed free . . . 3.6 3.6 4.1 3.8 treatments replicated four times. Maize was planted Two hoe using a rolling injection planter in April 1982. weedinas. . . . 2.7 2.6 2.9 2.7 2.8 The results in Table 31 show that the mucuna One hoe mulch drastically reduced weed seedling population weeding.. . . . 2.2 2.3 1.6 2.0 Cultlvar m ~ a n s (two seedlings per square meter, compared t o over 3.0 3.0 3.2 LSD (5Y/,): 18,000 viable weed seeds per square meter of topsoil). Fo A preemergence application of a formulated mixture ~ ~r suaclne".. cultivars and weed control. 0.3 For spacing x weed cont.rol . . . . . . . . . . . 0.4 of atrazine plus metolachlor (2.5 kg/ha) reduced it even further. The main problem was the smothering Note: Means for weed control are as follows: weed free, :37 tlha; two hoe wredings. '3.0 t/ha; and one hoe weeding, 2.5 f/ha. effect of volunteer mucuna plants on the maize. At harvest these covered 94'%, of the surface in the Table 28. Effect of cultivar, interrow spacing and unweeded plot, causing 70% lodging of the maize and weed control on weed biomass and rice a yield reduction of 43'%, (Table 31). Paraquat as a vield comnonents. IITA. 1982 directed spray did not prevent volunteer mucuna Weed dry Rice dry No. of No. of from having these adverse effects. Weeding once by weight," weight," tillers panicles hand pulling of volunteer mucuna a t six weeks aftcr Treatment g/m\/m2 per hill per hill treatment kept the population to a minimum. Cultivar: The hest yields were obtained in plots where OS6 . . . . . . . . . . . 92.7 1.29 38.1 22.1 volunteer mucuna and seedling weeds were con- TTA 118 . . . . . . . . 174.8 1.21 31.1 17.0 trolled with postemergence application of 2,4-D ADNY 11 . . . . . . . 110.1 1.09 53.1 41.2 (0.75 kg/ha) or with a formulated mixture of atrazine Spacing: plus metolachlor (1.0 kg/ha). The mucuna mulch did 15 cm . . . . . . . . . . 21.8 1.30 34.7 20.1 not completely eliminate weeding but reduced th r 30cm . . . . . . . . . . 144.2 1.28 40.2 27.5 45cm . . . . . . . . . . 211.6 1.01 47.4 32.7 use of Primextra from 5.0 ]/ha to 2.0 l/ha while Weed control: protecting the soil from erosion and ret,urning Weed free. . . . . . . 0 1.42 47.9 32.6 organic matter to the soil.--1.0. Akohundu, J.A. Weeded twice . . . 44.6 1.12 38.2 25.9 Paku and M.A. Gowman Weeded once. . . . 333.0 1.07 3fi.3 21.9 LSD (5%). . . . . . . . . 89.3 0.21 2.2 2.7 Effect of Herbicides on Nitrification Note: Spacing x weed control interactions had a nignificant To predict the inhibitory action of herbicides on !+'test for weed dry weight and number ofpanicles per hill. microbial activity i n t he field, t he effects of XAt9 0 days aftrr spraying. metolachlor, a trazine and fluometuron on the Farming Systems 151 Table 29 . Effect of herbicide combinations on weeds and cowpea yield. Mokwa. Nigeria. 1982 7 WAT At harvest Yield at All weeds. Veronia Grass Veronia Grass 12'.Y moisture . Treatment and rate. kg a.i./haa 2 WATb pauciflora weeds pnuciflora weeds kg/ha Weedfree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Metalachlor (2.0) + chloramhen (1.5) . . . . . . . . Metolachlor (2.0) + linuron (0.5) . . . . . . . . . . . . Fluazifop.hutyl(1.0) . . . . . . . . . . . . . . . . . . . . . . . Metolachlor + metohromuron (2.5). . . . . . . . . . Metolachlur (2.0) + chloramhen (2.0) . . . . . . . . Metolachlor (2.0) + linuron (0.25) . . . . . . . . . . . Pendimethalin (1.5) + linuron (0.5) . . . . . . . . . . Pendimethalin (1.5) + chloramben (2.0) . . . . . . Pendimethalin (1.5) + linuron (0.25) . . . . . . . . . Pendimethalin (1.5) + chloramhen (1.5) . . . . . . Mrtolachlor (2.0) + oxyHuorfen (0.3). . . . . . . . . Pendimethalin (1.5) + oxyfluorfen (0.3). . . . . . . Metolachlor (2.0) + oxyfluorfen (0.4). . . . . . . . . Pendimethalin (1.5) + oxyfluorfen (0.4). . . . . . . Weedycheck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LSII (5%) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ZAll herbicides were applied prcemergence to the crop and wrcds . crcept flunzifop.hulyl . hWeeks after treatment. Table 30 . Effect of herbicide combinations on weeds and cowpea yield. IITA. 1982 Weed dry Y irld at Crop injury rating Weed control rating weight . 1274 moisture . Treatment and rate. kg a.i./haa 2 WATb 5WAT 2 WAT 5 WAT kglha kg/ha Metolachlor + metohromuron (3.0). . . . 5 10 67 43 1. 160 914 Dinoseh (5.0) + chloramhen (2.0). . . . . . . 0 0 75 49 1. 145 862 Chloramhen (3.0). . . . . . . . . . . . . . . . . . . . . 5 8 9 0 38 1. 178 842 Pendimethalin (2.0) + chkrramhen (2.0) . 3 5 93 48 1. 120 858 Pendimethalin (2.0) + linuron (0.5). . . . . 8 3 74 50 1. 383 774 Metolachlor (2.0) + chloramhen (2.0) . . . 10 3 96 48 1.370 I. inuron (0.5) . . . . . . . . . . . . . . . . . . . . . . . . 8 5 79 23 2. 090 Metolachlor (.2 .0). + oxvfluorfen (.0 .3). . . . 60 23 93 61 865 Mctolachlor (3.0). . . . . . . . . . . . . . . . . . . . . 10 13 8 1 33 1. 575 734 OxyHuorfen (0.3) . . . . . . . . . . . . . . . . . . . . . 53 10 86 28 2. 068 610 Butachlur (2.2). . . . . . . . . . . . . . . . . . . . . . . 45 40 6 1 33 1. 885 5112 Mctolachlor (2.0) + hifenox (2.0). . . . . . . 75 55 91 53 1. 485 631 I'endimethalin (2.0) + bifenox (2.0). . 79 60 89 46 2.323 430 Bifenox (2.0). . . . . . . . . . . . . . . . . . . . . . . . . 84 70 98 40 2. 173 447 Rutachlor (17) + linuron (0.5). . . . . . . . . 28 25 73 40 1. 890 389 . . . . . . . . . . . . . . . . . . . . . . . . ... Weedycheck 0 0 0 0 2. 643 31.3 I S D (5%. ) . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1 318 "All herbicides were applird preemergence to the crop and weeds . "Weeks after treat.ment. numher and activity of nitrifying bacteria were During the first week of' incubation. micro- studied in soils from IITA. Mokwa and Onne. Three- organisms regained their activity following soil hundred-gram samples of air-dried soil were mixed wetting . and ammonification of organic N took place with the appropriat.e hcrhicides each a t 0. 2. 20 and readily . In the IITA soil. the number of nitrifying 100 ppm. representing. respectively. 0. 1. 10 and 50 hacteria was high. and nitrification proceeded times the normal rate of 3 kg a.i./ha. The soils were rapidly (Figure 27). hut ammonium N accumulated incubated for eight weeks in duplicate a t near field in the acid Onne soil. which contained very few capacity (16'yo) and a t 30°C . At weekly intervals soil nitrifying bacteria . moisture was adjusted before collecting 5-g samples The herbicides reduced the original population of of the moist soil for nitrifier counts and mineral nitrifying bacteria in the IlTA soil (Table 32) . At N content analysis . Bacteria counts were not per- 20 ppm fluometuron was the most inhibitory; only formed in samples containing 100 ppm of the 0.69: of the Nitrosomonas population and 5%. of the herbicides . Nitrobacter could be enumerated in the soil after 152 if7armingS ystems Table 31. Effect of Mucuna utilis dead mulch on weed control and maize yield, IITA, 1982 Percent No, of weed No. of viable coverageby Maize seedlings weed seeds volunteer Percent Yield. Time and rate of treatment, kg a.i./ha per 10 m"e r m b f soil" mucuna' lodgingr kg/ha Primextra" preemergence at 2.5 kg . . . . . . . . . . . . . . 3.8 9,072 73 26 2,019 Primcxtra, four weeks after planting a t 1.0 k g . . . . 16.3 18.144 30 13 3,055 t'a~.aquat,s, ix weeks after planting a t 0.5 k g . . . . 13.8 23,587 81 70 2,230 2,4-D, five wecks after planting a t 0.75 kg . . . . . . . . 18.1 16,330 26 13 3,168 Weeded once six weeks after planting . . . . . . . . . . . . 12.8 23,587 28 8 2,743 Unweededcheck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.9 18,144 94 70 1.746 LSD (5"%,). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 8.164 21 19 542 "Weed si,edlings were counted four weeks aftcr planting. "Based on nverage weight of $K,720 g10.13 cubic m oftopsoil (dry wright). 'Data on covrragr and lodging wrre t.aken s t crop harvest. Lodging is rxpressed as a percentagr of total maize populntiuri dI'rimextra is the trade name of a formulated miuturc oi'atrazine plus mctolnclrlur. Table 32. Effect of herbicides on number of nitrifying bacteria (logm/go f soil) and mineralization of organic nitrogen N/g of soil) in IITA and Mokwa soils, 1982 Nitrosomonus Nitrobacter NH,-N NO,-N Herbicide treatment IlTA Mokwa IITA Mokwa IITA Mokwa IITA Mokwa No herbicide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.94 2.92 4.02 3.46 4.65 3.88 50.95 30.27 Metolachlor 2pgm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.57 3.36 3.77 3.38 4.31 4.19 53.23 23.40 20ppm.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.62 3.66 3.42 3.57 4.25 3.52 55.39 31.26 100ppm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NDa NU ND ND 4.50 7.60 55.83 29.79 Atrazine 2 ppm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.59 3.31 3.76 348 4.58 3.31 49.27 30.77 20ppm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.30 3.88 3.69 3.45 4.90 3.69 52.04 32.13 100ppm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ND NU ND ND 410 3.88 57.33 30.83 Vluometuron 2ppm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.65 :439 3.88 3.67 417 3.85 47.19 38.60 20ppm.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.83 3.51 :i55 3.36 3.40 3.25 48.83 41.65 100ppm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ND NL) ND ND 4.44 5.04 56.96 42.71 ~ s n ( 5 ~ ; .0.). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.211 0.211 0 2 0.115 1.25 1.12 3.02 3.71 "Not determined. N03and NH4-N,ug/g Loglo microbial cou-n ts 5 Nitrobacter - I Number of weeks I<'igure2 7. Mineralization of organic nitrogen and evolution of nitrifying populations in untreated soils (incubated a t 30°C) fron>v ;o.ious locations in Nigeria, 1982. eiglit weeks of incubat ion, a s compared t o un t rea ted found in soil samples t rea ted w i t h metolachlor, s:rmples. However . t h e evolut ion of ammonium N w a s a t r az ine a n d fluometuron e a c h at 100 ppm. unaff'ected by t h e herbicides, a n d more n i t r a t e N w a s In t h e M o k w a soil, Nitrosomonas growth was stimulated in the presence of the herbicides studied improvement and suitability to alley cropping and (Table 32). With 20 ppm of atrazine, the Nitrosomonas to tcst the effects of' alley width and fertilizer population was more than 45 times the population in application. The experiment has a split-split plot the untreated sample after four weeks of incubation. design with three replications. Following an increase a t one week, the number of The tree species were pruned to a height of 60 cm Nitrobacter decreased in t h e presence of the in 1982, the second cropping year. Before the first herhicides more rapidly than in the untreated pruning at 11 months, height measurement.s showed samples during the last seven weeks of the large differences between species. Leucaena was thc experiment. These effects of herbicide on nitrifying tallest at 3.6 m, followed by gliricidia a t 3.2 m and bacteria counts did not reflect the changes in N alchornea a t 2.1 m. Acioa was shortest a t 0.6 m. Only mineralization; accumulation of ammonium N was small quanitites of dry prunings were produced in the observed only in soil samples treated with 100 ppm of second year by all four species, particularly acioa. metolachlor or fluometuron, and more nitrate N Because of its irregular and slow growth, the amount accumulated in the fluometuron treatment. of pruning from this species was negligible. Hiyher In the Onne soil, fluometuron a t 20 or 100 ppm biomass was produced per unit area with a 2 ~ mth an depressed nitrification but not mineralization of' with a 4-m alley width because of the highrr tree organic N. The effect of the herbicides on nitrifying population. With 4-m spacing leucaena produ(:ed bacteria in this soil could not be evaluated since only more biomass than gliricidia, hut with a 2-m alley a few nitrifiers were detected.-K. Mulongoy and Y. gliricidia produced more. Leucaena and gliricidia Arora - Agroforestry fertilizers applied to the companion crop. 1,arge differences were also noticed between species in thc Studies on alley cropping were continued in 1982 as composition of the prunings, as shown in Tahlr 34. part of IITA's effort to find improved alternat~vesto Gliricidia and leucaena prunings had higher con- the traditional bush fallow system. In alley cropping tents of N, P, K, Ca and Mg than those of alchornea food crops are grown in spaces between pruned and aciosi. Interestingly enough, hoth alchornca and hedgerows of shrubs or trees, which produce organic acioa are widely grown as natural fallow by residue and recycle nutrients. traditional farmers on the strongly acid soils in the humid zone where the cation supply is limited. Maize/Cowpeas Intercropped with Leucaena The eEects of alley cropping on minor season A trial was initiated in 1976 on a low fertility Apomu cowpea(V1TA-6) yieldsin 1981 areshownin Table 35. series soil (Psammentic Usthorthent) a t IITA, using a Yields responded well to residual fertilizer from the continuous function design with four replications. In previous maize crop. Since the fallow hedges were this trial the leucaena hedgerows were regularly not pruned in the first year of establishment, cowpea pruned to a height of about 150 cm. seed yield was lower with the 2-m alley width as a In 1982 the main season maize (variety TZPB) result of shading. Gliricidia depressed yield the most, responded significantly to addition of leucaena followed by leucaena, alchornca and acioa in that prunings (Table 33). Yields were lower than in order, which is more or less in line wit,h the size and previous years in treatments where leucaena leafiness of the trees. With t h e 4 ~ ma lley spacing, prunings were removed and no nitrogen was applied. alley cropping had no significant effect on the The addition of prunings and nitrogen kept yields a t cowpea yields, though in the no fertilizer treatment previous years' levels. alley cropping with gliricidia, alchornea and acioa The minor season cowpea (VITA-6) crop grew tended to give higher cowpea yields. better in treatments receiving leucaena prunings, Table 33. Effect of alley cropping maize and cowpeas although this was not reflected in the yields (Table with Leucaena leucocephala, IlTA, 1982 33). High rainfall during the pod formation and Maize (TLPR) Cowpca (VITA~6) drying period resulted in heavy pod borer infestation Treatment" yield, kg/ha yield, kg/ha (in spite of regular spraying with pesticides) and low Tilled seed yield. Cowpea yield was not improved by tillage 0 kg N/hah. . . . . . . . . . . . . . . 610 589 and actually declined in treatments receiving 0 kg N/ha. . . . . . . . . . . . . . . . 2.096 608 nitrogen fertilizer. The weed Talinum triangulare 40 kg N/ha. . . . . . . . . . . . . . . 2,671 472 was a serious problem in cowpea plots, particularly 80 kg N/ha. . . . . . . . . . . . . . . 2,911 481 the no-till plots, receiving leucaena prunings. No-till 0 kg N/hah . . . . . . . . . . . . 450 580 Tree Species for Alley Cropping 0 kg N/ha. . . . . . . . . . . . . . . . 1,566 528 40 kg N/ha. . . . . . . . . . . . . . . 2,293 537 A trial was started in 1981 on an eroded Egbeda soil 60 kg N/ha . . . . . . . . . . . . . . 2,423 491 series (Oxic paleustalfl with low N and P status to LSD 5 ) . . . . . . . . . . . . . 437 152 compare Gliricidia sepium, Leucaena leucocephala, "Nitrogen was applied to the first season maize crop. Acio barterii and Alchornea cordifolia for soil "Leucaena prunings wcre removed from the plot. 154 Farming Systems Yields of maize (TZPB) during the 1982 main Table 34. Nutrient composition of first prunings of season are shown in Table 35. With both the 2-m various tree species 11 months after and 4-m alleys, fertilizer application significantly olantine. IITA. 1982 increased grain yields. But when hedges were pruned Percent P P ~ periodically (acioa was pruned only once) during the Treatment N P K Ca Mg Cu Zu main season of 1982, alley width had no significant Gliricidia effecto n maize yield. It appears that gliricidia, which With fertilizera . . . 4.21 0.29 3.43 1.40 0.40 5.0 29.5 produced the largest amount of prunings in the Without fertilizer . 4.00 0.28 3.33 1.60 0.42 7.5 29.0 second year of the trial, also had the highest yield Leucaena response to alley cropping. With fertilizer appli- With fertilizer . . . . 4.33 0.28 2.50 1.49 0.36 21.0 32.0 cation the alley cropped maize produced higher Without fertilizer . 4.31 0.25 2.39 1.50 0.32 17.0 30.5 yields than the monocropped maize. It thus appears Alchornea that on this eroded Alfisol the beneficial effects of With fertilizer . . . . 3.29 0.23 1.74 0.46 0.20 18.0 34.0 alley cropping with leucaena, alchornea, acioa and Without fertilizer . 2.83 0.23 1.71 0.45 0.20 14.5 31.0 Acioa particularly gliricidia are already being felt. With fertilizer . . . . 2.57 O l f i 1.78 0.90 0.27 11.5 23.5 Without fertilizer . 2.38 0.15 1.94 0.81 0.30 7.5 24.5 Leucaena Alley Cropping With Upland Rice 'Applied to companion crop. A trial with rice was set up a t Ikenne on an Alagba soil series (Oxic Paleustalf) in 1981. The leucaena dry weights with application of lime, a t the rates of 0, hedgerows were pruned to a height of 60 cm, and 125,250,500,1,000a nd 2,000 ppm of CaC03w ere 1.04, during 1982 a large amount of leucaena prunings and 1.53, 1.90, 2.22, 3.21 and 2.93 glplant, respectively. a high N yield were obtained. Addition of leucaena Calliandra responded best to phosphorus, followed prunings and nitrogen had a striking effect on the by leucaena and sesbania. Seshania showed the growth andnitrogen status of the ricecrop. However, highest response to lime, followed by calliandra and a long drought spell during the flowering stage leucaena. It also appears that among the three tree sharply reduced yields. species tested, leucaena variety K-26 still performs the best, with low or high lime and phosphorus Lime and Phosphorus Response in Tree inputs.-B.T. Kang, G . F Wilson, T.L. Lawson and Species D. Koudoro A screenhouse trial was carried out to determine the Alley Cropping and Microclimates suitability of certain tree species for alley cropping on acid soils. The Ultisol was collected at Amakawa Studies a t IITA have shown that alley cropping is a in eastern Nigeria. The lime and phosphorus promising method of land and crop management. responses of three wooded species, Calliandra Further information is needed on the usc of physical caolothyrsus, Leucaena leucocephala and Sesbania resources and competition for those resources in the grandiflora, were tested in this pot trial. alley cropping system. Without that information the All three species responded significantly to lime efficiency of the system cannot be improved and ~ h o s ~ h o r uapsp lications (Table 36). The mean systematically. Table 35. Effect of allev croo- v- in-e on minor season cow.pe a .yi eld and main season maize yield, IITA, 1982 Treatment Control Gliricidia 1,eucaena Alchornea Acioa Mean Cowpea (VITA-5) Yield, kg/ha 2-111 spacing, without fertilizer . . . . . . . . . . . . . . 904 388 765 740 1,043 768 4-m spacing, without fertilizer . . . . . . . . . . . . . . 1,048 1,619 1,133 1,626 1.637 1.412 2-m spacing, with fertilizer . . . . . . . . . . . . . . . . . 842 403 629 781 1,011 733 4-m spacing. with fertilizer . . . . . . . . . . . . . . . . . 1,829 1,698 1,519 1,535 1,457 1,608 Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,156 1,027 1,012 1,171 1,287 Maize (TZPB) Yield, kg/ha 2-m spacing, without fertilizer . . . . . . . . . . . . . . 1,343 1,943 1,111 1,154 1,249 1,360 4-m spacing, without fertilizer . . . . . . . . . . . . . . 1,619 2,221 1,203 1,527 1,620 1,638 2-m spacing, with fertilizer . . . . . . . . . . . . . . . . . 2,360 3,471 3,471 2,776 2,823 2,980 4-m spacing, with fertilizer . . . . . . . . . . . . . . . . . 2,684 3,471 3,377 3,285 3.378 3,239 Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,002 2,777 2,291 2,186 2.268 LSD (5'%,) hetween: Cowpeas Maize Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374 390 Spacings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279 318 Fertilizertreatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 556 Fert, treatments for same s~ecies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 273 Species for same spacing and fert. treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 681 888 "Fertilircr was apphcd at a rate of W-40-40 kg/ha to the main season maize crop. u! 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Jeau sdom OR'Z IL'Z 802 " " " " ' mdd 09Z ! w Z . . . . . . . . . . aq? uo luap!3u! uo!7e!pu~ [eqol3,jo a3e luaa~adar [A 89'Z "dd 9ZI .saYpa qloq qe pue SMOJ aql,)o a[pp!ur aql u! 3uqdures 991 ZP'Z CP'I am![ ON ' ,-I Wdd 0s xe [n3a~q Bno~yqp alaalap aq pIno3 spuall ?uals!s 69'0 ". -uo3 ON .suzaq$ed [ l e ju !e~Sqp aauanuu! S[luap!~a ZR1 ES.1 ueam 96'7. PL'Z 89.0 . "3e3 tudd 0 0 0 ' ~ SUM pug SMOJ ewae3n31 aq? uaaMlaq uo!l!sod 6 s ' ~ OC'Z 08.1 . . . . . . . .m dd oon'r aq l oq Y u ~ p ~ o a apea! aeA lualuoa aJnls!otu 110s ? ' 6. . . . . . . . . . Z CO'Z mad 00s 'syaolq aan?s!om aauels!sal pun slalaurorsuq I 9oz SI.1 8S.O . . . . . . . . . LUdd 0% yl!M pue L[[ea!qaur!~e~S yaaM e aauo palol!uour L O CI'I ';yo 9P'O ". .". .". . . . . LUdd 9ZI seM aJnls!om [!OS 'euaeana~a yl jo Su!urud yaea Ja4.p HZ0 01'0 Z P O am![ ON pus aJojaq slalaru!Jr?[os aqnl~Buoq1 l ! ~pa Jnsuatu seM d ON (sLa[[e ur-p a q l j o a[pp!ur) Lemx: lsaqlJaj asoql uo pun u n . 3 ~ e!uoqsas euaenna? eJpue![[e:) ale2 am!^ s ~ oeul a eana[ a y l o l as013 s d o ~uao lqS![jo aauap!au! lunrd!R ' ~ X ~ J LMJD loouc: pue snloqdsoqd a q ~ ,.s p{a!L d o n uo slaaga pue sJ!qs!Jaq3emqa 7,861 'VLII 'Bu!$ue~dJ alJe SyaaM arayq azL[eue o l (Sq![!1.1a.j pas uo uoqaas aql u! 8 u u n p1 sa!aads a a q sno!Jeh jo p[a!k JaTTern .i.8Lq uo p a l ~ o d a ~lu)a ur!xadxa 3u;ddo~a. <31[e u e k.rp uo sn~oqdsoqdp ue Su!ur![jo q a a a 3 . 9 ~a[ qe& u! palnseauc aaaM uo!lnqqs!p axnls!om put: lyYy1 156 Farming Systems Germination ( % I clay pots and kept a t lo0, 20°, 25'and 36'C for 28days. One set of seeds was treated with hot water to hreak dormancy, while the other was untreated. The experiment had a split-plot design, with seed treat- ments as main plots and temperatures as subplots and six replications. Each subplot had 100 seeds. There was no germination a t 10°C, but from 15°C the germination rate increased until 25OC and then decreased appreciably a t 35%. Total germination 50 - Oven storaae (Figure 29) was more or less the same between 15'and 30°C but was significantly lower a t 35OC. Weed Control After Leucaena and Natural Fallows In addition to restoring the chemical and physical properties of the soil, a good fallow is expected to v purify the field by reducing the population and effects of pathogens, insects and, most of all, weeds in ‘v' "T succeeding crops. Though Leucaena leucocephala Cold storage 20 k fallow reduces the population of many common ( I to4OC) weeds, leucaena itself can become the major weed after the fallow. The effect of leucaena as a weed on maize yicld was compared to the effect of weeds after natural fallows during the same one-year period. The design of hoth trials was a split plot, with tillage (rotovation and no-tillage) as the main treatments and three levels of atrazine as the suhtreatments. After leucaena fallow the plot was alley cropped (alleys 2 m wide). The trees were cut back t o 0.3 m, the Storage duration ( months) trunks and large stems were removed, and the leaves Figure 28. Effect of storage duration and conditions on and small twigs were left as mulch or green manure. leucaena sped germination eight weeks after planting, With green manure, the leaves and twigs were IITA. 1982. incorporated during rotovation. In the tillage with mulch treatment, the land was rotovated before the mulch was added. With natural fallow, the plant cover, mostly grasses, was killed with glyphosate, and the residue was used as mulch or green manure. Germination (%) Fertilizer was not applied in either case. After leucaena fallow tillage and plant residue t management had no significant effect. Atrazine at m LSD(S%) only 3.0 kg a.i./ha controlled weeds significantly Treated seed I same seed treatment better than the control. With natural fallow tillage @ Untreated seed T different seed was slight,ly better than no-tillage, and hoth atrazine treatment levels were significantly better than the control (Table 38). In general, t,he maize yields were good, considering that fertilizer was not applied. The maize yield after leucaena fallow in the first season was low possibly because the leucaena was not given a third pruning and its regrowth partially shaded the maize during the grain filling stage. In the second season, the lcucaena was pruned a third time. Direct comparison of the two fallows shows that there was less weed competition after leucaena fallow than after natural fallow. After leucaena weed control resulted in yield increases of 40%, i n the first and 70%)i n the second season. After natural fallow weed control increased Temperature P C ) yields 377%, in the first and 260';{, in the second Figure 29. EfSect uf temperature and seed treatment on season. In reducing weed competition, leucaena germination of 1cucaen:r seeds 14 days aftcr planting. lITA, fallow has an advantage over natural fallow domina- 19x2. ted by grasses, where maize is grown after the fallow. Farming S.ystems 157 Fertilizer, Mulch and Green Manure in Alley Cropping The effects of leaves and twigsprunedfrom (;lil.icirlia sepium on maize yield were tested in an alley cropping system with 3.75-m spacing between rows. The lcaves were used as mulch or green manure. The experiment had a split-plot design. The main treat^ ments were NPK fertilizer (each applied a t 60 kg/ha a t planting plus 30 kg N/ha as a side-dressing four weeks later) and no fertilizer. The subtrcatment,~ were leaves and twigs as mulch and leaves and twigs incorporated as green manure. Maize was grown during the first season a t spacing of 75 cm x 25 cm. The fertilizer treatment gave significantly higher yields than the no fertilizer treatment. There were indications tha t using leaves as mulch or green manure had some beneficial effects, although thc yield was not significantly different from that of thr control. This trial will be continued to determine the c:umulative effects of leaves as mulch and grecn manure over several seasons and years.-G.1.'. Wilson and A.N. Atta-Krah Gliricidia Prunings as a Nitrogen Source The efictivencss of Gliricidia sepium tops as a nitrogen source (applied fresh or after drying). compared t o urea fert,ilizer, was tested on a sandy Apomu series soil (Psammcntic Usthorthent), using Figure 30. E&ct of urea and Gliricidia nitvoycn appli- maize as the test c rop A field trial was set up in cation on m a i m yield, IITA, 1982. a randomized ctlmplete hlock design with four replications. The urea nitrogen and gliricidia tops wcre applied (one-third of the N a t planting and Leucaena/Maize/Yam On-Farm Trials two^ thirds two weeks after planting) in bands and then In addition to the objectives st,ated in previous IITA covered. All treatments received basal P and K Annual Reports, the long~termo n~farmt rials of dressings. maizelyam alley cropping with 1,eucaena leucocc- Thc maizc yields were low hecause of errat.ic phala had thc following goals during 1982: (1) to rainfall. Addition oC urea and fresh gliricidia tops as check the suit,ability of leucaena stems as live in-situ fresh and dried materials a t rates equivalent to 40 kg stakes for yam vines under f;irm conditions: to Njha and 80 kg N/ha significantly increased maizc observe farmers' prohlems wit,h the management of yield (Figure 30). At the lower rate of 40 kg Njha. yam/leucaena ;illcy cropping; to assess farmers' gliricidia tops were less effective than urea. Though perceptions of the system; and to obtain other. yield differences between fresh and dried gliricidia feedback for further improvement of the system. tops wcre not significant, the fresh tops appear to he By the end of 1982, ten on-farm trials of lcucaen;i/ mllre effective as :I nitrogen source than the dry tops. maizelyam allcy cropping had been established. five The dry material. though. is easier to handle because of which were started in 1980. three in 1981 and two in i t is less bulky. B.1: Kang 1982. The locations of the trials are Ijaye in Oyo State, Osara and Tawari in Kwara State and Yzmdev. Tyowanyc and Zakibiam in Renue State. In addition. some alley cropping trials were started in 1982 in Table 38. Effect of weed control on maize yield after cooperation with the Ayangha and Ekiti-Akoko leucaena and natural fallow (linear contrast for three values). IITA. 1982 Agricultural Development Projects. Most of these trials arc located in the Guinea 0 2.5 3 Effect savanna, the midbelt of Nigeria, where yams are the kg/ha kg/ha kg/ha Contrast Avg. predominant crop, though staking materials are Leucaena fallow tjhn quite scarcc. For example, in Zakibiam, the center of First season. . . . . . . 2.74 3.37 3.88 1.14 0.57 yam production in Ucnue State and an area where Second season.. . . . 1.48 2.43 2.56 1.08 0.54 farmers' specializatic~nin yam production is probahly Natural fallow the highest in Nigeria. farmers [lo not stake their First season. . . . . . . 0.95 4.53 4.53 3.58 1.78 yams. From informal surveys carried out in this area, Second seasun.. . . . 0.68 2.40 2.47 1.79 0.90 i t is clear that farmers understand the value of Farming Systems 159 spacing between and within rows of the leucaena This field was weeded regularly. The effects of the bushes. The early trials were planted a t 2 m x 0.5 m different land management and live mulch treat- and the later ones a t 4 m x 0.5 m. In the former, ments on soil properties and crop yield were reported farmers could make only one row of mounds, and in the llTA Annual Reports for 1979, 1980 and 1981. even then some farmers complained that 2-m spacing This discussion is concerned only with N data from is too narrow for their yam heaps. The 4-m row the live mulch and unmulched plots that were spacing seems more reasonable, although some conventionally tilled, received 0 or 120 kg N/ha, and farmers think it gives too high a proportion of trees were weeded or not as indicated. per unit land. A third problem is mechanization of the The shoot dry weight of the cover crops averaged 4 alley cropping system for ploughing or pruning of the t /ha, and root dry weights ranged from 0.4 to 2.65 leucaena bushes to reduce labor requirements a t t /ha. In both fields live mulches contained 89 to 161 pcak periods, especially for t he medium scale kg N/ha a t maize harvest, but their N contents farmers. exceeded 200 kg N/ha during the cropping season, In addition to pointing out problems that require and they were not affected significantly by N further research, farmers have commented that fertilization and weeding (Table 39). leucaenalyam alley cropping has definite benefits. It In the newly established field, the N uptake by provides inexpensive staking materials for yams. The maize was ahout the same a t 0 and 120 kg N/ha and yam crops in the leucaena plots look much better was the lowest in centrosema plots. The N contri- than those in the controlplots. The leucaenacontrols hution from the cover crop (calculated as the weeds, especially Imperata cylindrica, and i t keeps difference between the N content of maize in live the soils moister and more friable. When farmers mulch plots and its N content in plots without live ploughed they found the soils in the leucaena plots to he softer and easier to plough than those in the Table 39. Nitrogen uptake and yield in a newly control plots. established and a long-term mulch plot, 1,eucaena also improves the fertility of the soil. IITA. 1982 Soil tests on these plots done in November 1982 Arnount of N indicate that since the last tests in June 1981 some Total N. kg/ha contrthutrd to soil chemical properties have improved significantly. l ive maize by livc Total nitrogen in the soil has increased by over 60%,. Treatment mulch maize mulch. kg/ha 'The pH of the soil has increased by up to 870, and the New plot percentage organic carbon in the soil has also been No N fcrtilizcr raised. No live mulch . . . . 0 34.0 0 Another benefit recognized by farmers (especially Centrosema.. . . . . . . . . . 95.0 9.2 -24.8 in the Guinea savanna) is that leucaena trees provide I'sophocarpus . . . . . . . . . 114.0 20.4 -13.6 firewood and fencing materials. Two farmers in- 120 kg N/ha dicated that they plan to increase the land under No live mulch . . . . . . . . . 0 38.0 0 leucaena to 2 ha each. The fact that, other farmers Centrosema . . . . . . . . . . . 116.0 16.0 2 2 . 0 Psophocarpus have taken an interest in leucaena at two of the . . . . . . . . . 108.5 27.2 - 10.8 LSD (5%). . . . . . . . . . . . . . . 64.0 13.6 18.4 locations and have requested seed is a further indication of the benefits of alley cropping with Long-term plot leucaena. D.S. Ngambeki Weed free, no N fertilizer No live mulch . . . . . . . . . 0 60.0 0 Centrosema . . . . . . . . . . . 99.0 39.2 -20.8 Live Mulches and Cover Crops Psophocarpus . . . . . . . . . 104.5 63.2 3.2 Arachis.. . . . . . . . . . . . . . 160.5 37.2 2 2 . 8 Nitrogen Uptake in Live Mulch Systems Weed free, 120 kg N/ha No live mulch . . . . . . . . . 0 82.0 0 To evaluate the N contribution of Psophocarpus Centrosema . . . . . . . . . . . 130.0 68.4 -13.4 palustris, Centrosema pubescens and Arachis repens Psophocarpus . . . . . . . . . 89.0 108.8 26.8 in live mulch systems a t IITA, total N uptake was Arachis.. . . . . . . . . . . . . . 133.5 105.2 23.2 assessed a t maize harvest in a newly established field Weedy, no N fertilizer and in another one that had been cropped con- No live mulch . . . . . . . . . 0 16.4 0 tinuously for six seasons. The latter was a three Centrosema.. . . . . . . . . . 117.0 76.0 59.6 Psophocarpus . . . . . . . . . 133.5 60.4 44.0 replication split plot with diff'erent types of land Arachis.. . . . . . . . . . . . . . 156.0 29.2 12.8 management and live mulches as the main plots and Weedy, 120 kg N/ha different levels of N fertilizer as subplots. Some parts No live mulch . . . . . . . . . 0 49.2 0 of the plots were not weeded, others were kept clean, Centrosema . . . . . . . . . . . 120.5 83.6 34.4 and some were weeded once. Psophocarpus . . . . . . . . . 102.5 98.0 48.8 The newly established field was a four-replication Arachis.. . . . . . . . . . . . . . 110.5 40.4 -8.8 split plot with different types of land management LSD (5%). . . . . . . . . . . . . . . 78.0 38.0 28.4 and live mulch (only C. pubescens and P. palustris) =Values were calculated for a maize population of 40,000 as the main plot,s and N fertilizer rates as subplots. plantslha. 160 Farming Systems mulch was negative, indicating that the live mulch Table 40. Main stem length and dry weight of two and main crop competed for N. This finding leeume soecies five weeks after aoolication corroborated earlier observations that P. palustris oFa ggrow'th retardant, IITA, 1982' ' and C. puhescens nodulatcd poorly a t TITA and that Plant stage at CGA rate, kg/ha their symbiotic N tixation was low. CGA appl~cation 0 2 20 In the long-term field, N uptake by maize was lowest in the weedy plots that had no live mulch and Psophocarpus Main stem length, cm received no N fertilizer. Also, because weed control 15 days after planting . . . . . . 91.79 29.34 17.07 was poor in arachis, N uptake by maize was 111w in 30 days after planting . . . . . . 138.96 57.29 34.07 unweeded plots having this legume as live mulch. A. 45 days after planting . . . . . . 196.30 111.98 79.35 repens in weedy plots contributed the least N. Centrosema The N 15 days after planting . . . . . . 53.46 17.61 14.97 contribution of P. palustris was gener;illy superior, 30 days after planting . . . . . . 86.76 34.93 23.12 averaging 30.7 kg N/ha. This represents only a small 43 days after planting . . . . . . 102.14 86.43 75.91 fraction of the live mulch N, especially if the total LSD (5%,)f or comparing means of: litter produced from the legume over the cropping Psophocarpus, same CGA trtmt. . . . . . . . . . . . . . . 43.83 season is taken into consideration. K. Mulorzgoy Psophocarpus, diff.C GA trtmts. . . . . . . . . . . . . . . 53.08 and 1.0. AIzohundu Centrosema, same CGA trtmt.. . . . . . . . . . . . . . . . 30.66 Centrosema, diif. CGA trtmts.. . . . . . . . . . . . . . . . 30.16 Use of a Growth Retardant in Live Mulch I'sophocarpus Dry weight, glplant Systems 15 days after planting . . . . . . 38.39 36.07 13.49 30days after planting . . . . 58.78 54.13 15.37 The purpose of this study was to describe the growth 45 days after planting . . . . . . 75.98 61.32 32.28 patterns of Psophocarpus palustris and Centrosema Centrosema pnhescens as affected by CGA 47283. a growth 15 days after planting . . . 62.88 33.83 22.66 retardant used to prevent these legumes from 30 days after planting . . . . . . 54.37 44.55 20.48 climbing and strangling associated crops in live 45 days after planting . . . . 61.47 60.10 33.43 mulch systems. The growth retardant was applied on I,SU (5%) for comparing means: the cover crops a t rates of 0, 1 and 10 times the For same CGA treatment . . . . . . . . . . . . . . . . . . . . . 20.0 recommended rate of 2 kg CGA/ha. At the time of For different CGA trciltmcnts . . . . . . . . . . . . . . . . . 31.0 spraying. t he legumes were: 15, 30 and 45 days old. One, five and nine weeks after CGA application, the length of t,he main stem was measured, and the of t.hose on unsprayed plants. At that stage stem number uf' nodes ;md branches on this st.em were elongation was generally inhibited by CGA, but the counted. formation of nodes was not. Sprayed plants produced Leaf' burns wcre noted the second day after appli- greener and smaller leaves than those that received cation of the growth retardant. These were more no CGA treatment. Nine weeks after CGA appli- mzirked in the treatment tha t received 20 kg CGA/ha. cation, newly formed internodes on the main stem of The plants recovered in two or three weeks, but sprayed plants werc more than 5 cm long, hut elongation of their main stem was visibly reduced. psophocarpus sprayed with 20 kg CGA/ha 15 days Five wceks after CGA application, the mean height after planting showed 87:/, inhibition of internode of the main stem of psophocnrpus sprayed with 2 and elongation. 20 kg CGA/ha was, respectively, 47 and 31'%,o f that of Shoot dry weight of the cover crops was evaluated unsprayed plants; for ccntrosema, 43 and 53'%, five and nine weeks after CGA application, and inhibitions werc recorded for the corresponding nodulation of psophocarpus only was observed 8 and treatments (Table 40). Only plants sprayed 15 and 30 16 weeks after application of the growt,h retardant. days after planting were xffectecl by the growth At five wceks 20 kg CGA/ha had r:aused 70'2, retardant. Nine weeks aftcr application of CGA, inhibition of dry matter production in 65-day-old growth inhibition persisted in centrosema plants plants of psophocarpus and 50'><, in centrosema that, had been sprayed wit.h 20 kg CGA/ha 15 days (Table 40). Four wceks later all the plants that had after p1ant.ing and in psophocarpus plants that had been sprayed with 20 kg CGA/ha exhibited reduced received 2 kg CGA/ha a t 15 days after planting or 20 dry matter production, compared to plants of the kg CCA/ha a t 15 and 20days after planting. Thus, the same age in theunsprayed control or in the treatment inhibitory effect of CGAon mair~st emelongation was that received 2 kg CGA/ha. This pattern could not be more marked on plants sprayed a t a n early growth predicted from the height and number of nodes and stage. and psophocarpus was more sensitive to the hranches on the main stem since a t that stage all chemical than centrosema. these factors tended to he similar in t he CGA and no Internode length was also atfected by the growth CGA treatments. The small size of the leaves may retardant. One week aftcr C(:A application, inter- account for the reduced dry weight in thc CGA nodes averaged 2.4 cm long for psophocarpus and treatments. 3.0 cm for ccntrosema, respectively, with no differ- At 8 and 16 weeks aftcr application, the chemical ences between CG.4 treatments. After four weeks t,he retarded nodulation of psophocarpus when applied a t internodes of sprayed p l ;~ntws ere about half the size 20 kg/ha. At a low rate (2 kglha), inhihition was Farming Systems 161 significant only on plants that were at least 14 weeks old a t the time of sampling. The fact that CGA retards nodule formation and development suggests that it Lawson and 1.0. Akobundu reduces the symbiotic N fixing ability of P. palustris, lessening its usefulness as an N source in live mulch Crop Yield After Two Planted Fallows systems. In the future we will evaluate the effects of A long-term trial on the effects ofplanted fallow trees CGA on fixing of atmospheric nitrogen by nodules. on soil chemical properties and crop yield was begun K. Mulongoy in April 1981 on plots of Acioa barterii and Gliricidia Soil Climatic Regimes in Live Mulch sepium that had been established four years earlier. Each plot measured 8 m x 2 m, and the row spacing Systems was 1 m. The experiment had a split-plot design with As part of a comprehensive evaluation of live mulch the fallow trees as whole plots and the fertilizer production systems, changes in soil moisture in treatments (fertilizer versus no fertilizer) as subplots. different surface mulch/crop combinations were The control was natural regrowth (mainly grass followed during both cropping seasons in 1982 (this weed fallow). There were three replications. study was a continuation of one reported in the IITA A. barterii and G. sepium stands were pruned a Annual Report for 1981). The objective was to assess second time to a height of 50 cm in April 1981, and the the moisture regime and moisture availability under leaves and fine twigs were spread out evenly as a the system and to confirm the validity of previous mulch in the plots. Weeds were controlled in G. results. sepium and in the control plots by application of Those results indicated that there is considerable paraquat. There were no weeds in the A. barterii interplay between the amount, rate and frequency of plots. The test crops were maize in the first season rainfall and the observed moisture regimes. The and cowpeas in the second. Fertilizer (60 kgN/ha, 125 trends observed then still hold. Moisture infiltration kgP/ha and 60 kgK/ha) was applied only to the first into the soil is evidently higher in mulch/crop season maize. A. barterii regrowth was pruned once combinations than with bare or poorly covered soil and that of' G. sepium twice to prevent shading of surfaces. The soil moisture content under live crops. Changes in the amount of leaf residue were mulches also remains higher except after prolonged monitored a t monthly intervals. drying cycles. With regard to these properties, The Gliricidia sepium plots had the highest yields psophocarpus and maize stover are best, Arachis and of first season maize (Table 41). Fertilized plots no-till are often the worst, and centrosema and yielded significantly more than unfertilized plots in conventional tillage are generally in hetween. all fallow treatments. The cowpeas in the natural There is evidence that the treatments interact with regrowth fallow yielded significantly more than that soil fertility (N fertilizer level) and soil type. The no- in other treatments, except unfertilized G. sepium. till treatment ranks highat high soil fertility on light Cowpea yields were generally lower in 1982 than in soil (Apomu) and is also better than other treatments 1981 because of a 24% deficit in precipitation on a heavier soil (Egbeda) a t lower fertility. For the The residue of A. barterii decomposed very slowly same mulch/crop combination, soil moisture content (Figure 32) and the persistent mulch it formed is also higher, in most cases a t a higher fertility on prevented weed growth and eliminated the need for lighter soil. weeding throughout the trial. Since weeding is often As expected, much cooler soil temperatures prevail the largest labor input in bush fallow agriculture, the under live mulches (psophocarpus and centrosema), A. barterii fallow could free a large part of the labor particularly during the dry season and early in the force for expanding production. The mulch also first season. Differences in weekly mean maximum protects the soil from erosion and adds to the soil temperatures may reach more than 10°C during the organic matter content.-G.F. Wilson and P.S. Okoli dry season and near 5'C during the early rains (Figure 31). These differences could have a con- siderable effect on biological activity in the soil during the dry season and possibly on seedling growth during the growing season. On the basis of these and previous results, certain broad criteria may be used in choosing mulches for particular situations. First, heavy surface mulches are unsuitable in areas and during seasons with very light rainfall, even if rains are frequent. Second, actively growing live mulches do not appear suitable loo 0 0L 4 6 -6 -I0 -I2 1l 2 I0 I8 I0 I6 in areas or during seasons of erratic rainfall with prolonged periods of moisture depletion between W e e k o h r planting rains. Live mulches should not be used if these Figure 31. Trend in weekly mean maxlrnum temperatures periods last more than 10 to 15days, depending on the under different rnulch/crop cornhlnat~ons and tillage soil type and amount of preceding rainfall. Finally, methods, IITA, 1982. 162 Farming Systems Plantain Research Mulch and Illorganic Fertilizers The major concern of farmers undertaking large An experiment was started t o examine the eEect,s of scale production of plantains (Musa sp. AAB) is the mulch plus fertilizer, mulch alone, fertilizer alone rapid decline in yield after the first harvest. Previous and a control without mulch and fertilizer. Two studies have shown that a low soil organic matter plantain cultivars (a giant and a medium false horn) content may he one of the main causes of this decline and a banana cultivar (paranta) were planted in a and that productivity can be maintained if organic randomized complete block design wi th four material is applied frequently as mulch. Recent IITA replications. Fertilizer was applied a t t he rates of 300 plantain research has focused on the effects of kg N/ha and 500 kg KzO/ha per annum in five equal mulches and on the development of efficient, applications over 10 months. Mulch from elephant mulching techniques. grass (Pennisetum purpureum) was applied three times a t a rate of 10 to 15 t /ha to give a total of 40 Table 41. Effect of planted fallow species on maize t /ha/yr (fresh weight). and cowpea yield, IITA, 1982 The mulch plus fertilizer treatment was signi- ficantly better than the others in terms of early Cliri- Acioa c~dla Natural maturity, hunch weight and yield (Figure 33). The Treatment barterri seplum regrowth Mean height of the first sucker increased with fertilizer but decreased with mulch. Judging from yield response, First season Maize yield, t/ha the giant false horn appears to be more tolerant than Fertilized . . . . . . . . 4.4 6.0 3.8 4.4 the other cultivars to low soil fertility. The medium Unfertilized . . . . . . 3.1 3.7 2.7 3.2 false horn and paranta matured much earlier with Second season Cowpea yield, t/ha mulch and fertilizer. These results agree with Residual fertilizer. 0.404 0.536 0.692 0.544 previous findings that mulch alone is often as Unfertilized . . . . . . 0.408 0.628 0.6:il 0.556 effective or hetter than fertilizer alone. The final LSD (ST>f) or comparing: Maizc Cowpeas conclusion will depend on the performance of the Species . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 0.212 crops in succeeding years. Fertilizer treatments. . . . . . . . . . . . . . . 0.4 0.079 Fert. trtmts., same sprcics . . . . . . . . . . 0.7 0.136 In-Situ Mulch Fert. trtmts., ditf. species. . . . . . . . . . . . 1.3 0.233 C.V., 'x> In the management of plantain plantations, a major Species. . . . . . . . . . . . . . . . . . . . . . . . . . 19.1 24.0 drawback t o using mulch is t h e high labor Fcrtilizer treatments. . . . . . . . . . . . . . . 9.6 12.4 requi~emento f cutting, transporting and applying the organic materials commonly used in the humid tropics. To overcome these problems research is being carried out on in-situ mulch production. The methods being tested are two spatial arrangements in which the mulch producing plants are grown close to the plantains (Figure 34). 111 one of these spatial arrangements, every four rows of plantains (spaced 2 m x 2 m) arc separated by an equivalent area of mulch, with a 2-m border between the mulch source and plantains. In the other arrangement each pair of plantain rows is separated by an equivalent area of mulch, leaving a 1-m border between the plantains and mulch source. The species used for producing mulches were Flemingia congesta. Eupalorium odorntum and Pennisetum purpureum. The mulch was cut and applied to the adjacent plantains three times a year. The plantains also received inorganic fertilizers a t rates of 300 kg N/ha and 550 kg KaO/ha per annum applied in five equal applications over 10 months. The design was a split plot with three replications. The main plots were the mulch sources and the subplots were the spatial arrangements. In bunch weight (Table 42) there were no significant differences between spatial arrange- ments, but there were significant differences between types of mulch. P. purpureum and the control were Weeks after prunnlng marginally better than F. congesta. P. purpureum Figure 32. Change over time in the amount of Acioa harterii was also better than h'. odoratum. leaf residue, IlTA, 1982. DiEerences in yield between the two spatial li'arming Systems 163 Sucker height ( cm ) 240 o & Medium false horn Giant false horn Figure 34. Arrangements of plantain and mulch source plants for in situ mulch production, Onne, Nigeria. plants adversely in the close spacing.-R. Suennen and G.F. Wilson Farm Inputs and Equipment No-Tillage Planters and Sprayers for Small Farms Yield (t/ha) 20 Establishing a good stand in a no~tillages ystem is usually more difficult than in a conventional tillage ..~st~!~i.'l'~~,i~t~~h~;.itn p~Ii;~in~tk~.\r<\~ n~t1~11r~1\\1 11. 10 1. I~ , -~ 1 I,, 51 ~.>l:ll~ll..lllllt.ll\\l. I111 ~ 1 1 1 1 , 1 , . 1 1 1 1 1 0 1 1 1 1 ~ ~~ ~ planters, several tests were (:onductcd this year. Modifications in the Rolling Injection Planter Certain modifications were made in the planter to increase its effectiveness in establishing a good stand. The length of the openers was increased from 50 to 70 mm t,o achieve deeper seed placement, and the configuration of t he press wheel was changed t o achieve hetter seed-soil contact. Tests were made in both growing seasons of 1982 in maize. A total of 10 combinations of openers and press wheels were tested in an experiment that had a complete factorial design with eight replications. A depth of seed planting test was done simultaneously ., with each of those tests. Single seeds were planted a t depths of 0,10,25,50,75a nd 100 mm. Each treatment Control Fertilizer Mu'lch Mulchtfertilber had 25 seeds. The planting procedure was as follows. Figure 33. Effect of mulch and fertilizer treatments on yield A cylinder with a diameter of 50 mm was pressed into and first sucker height of banana cultivars, Onne, Nigeria, the ground to the desired depth of planting. The 1982. cylinder was pulled out with the soil core. One seed was dropped into the hole, and the soil core was arrangements were due to differences in plant pushed hack in to cover the seed. Best establishment density. The lower yield in t h e first spat ial was achieved between the depths of 25 and 50 mm, arrangement is the result of its lower plant density and i t was usually good up t o 75 mm. and could he a disadvantage if the trend persists in As for the planter modifications, the 70 mm opener the ratoons. The significantly lower yields of E. gave consistently better establishment, hut the odoratum and F. congesta in the second spatial different press wheels failed to improve overall arrangement suggest that the mulch source and crop establishment, compared t o tha t with the original compete. There were also indications that shade press wheel or with no press wheel a t all. The failure from the plantains was affecting the mulch source apparently had two causes, the first of which was 166 Farming Systems Sixteen observations each of10 m of row length were Comparison of Cowpea Harvesting made for both setups. General field conditions during planting were very favorable and the difficult wet Methods and soft conditions required for test ing th is Previous work has shown that determinate upright configuration did not occur. The two setups were cowpeas (04-0267-117) can he cut mechanically a t 5 ern equally effective in plant estahlishment. The t,ests above the ground with field losses of 13'%:,S. etting the will be repeated under unfavorable conditions in cutter bar higher caused field losses of more than 1983.- C . G armun 35% of the potential yield. With a spreading type cowpea like VITA-5 losses were 45U/, when the cutter Hand-Pulled Boom Sprayer bar was a t 6 cm (Table 43). In 1982 comprehensive tests were made to compare Small farmers need more uniform and safer four different methods of harvesting: (1) manual application equipment for herbicides. Hand appli- picking, which involves picking the pods and drying cation using a knapsack sprayer with a 1.5-m spray them before threshing; (2) plant harvesting and pattern width has several serious problems: spraying windrowing, in which the plants are cut or pulled,six is not uniform because of the large overlap per rows are piled in one windrow, and plants are hectare; the spray operator contaminates himself by threshed after drying; (3) cutting with a one-row walking through the area just spray&; he must carry cutter bar conveyor, which cuts most of the pods and heavy loads of water; he may spill spray mixture on a small amount of straw, followed by drying and himself; and spraying with this equipment is very threshing; and (4) the one-row combine harvester. a time consuming. simulated system using the same cutter bar conveyor A hand-pulled wheeled sprayer with a 4-m boom used in treatment 3 and a standard rubber roller type was built that reduces the overlap problem by 67%. thresher a t the same time. (The same thresher was The spray operator walks in fkont of and pulls the used to thresh the other harvests). sprayer and does not have to walk through the Ahout one-fifth hectare of cowpeas ready to sprayed area a t any time. Since the operatur is harvest was subdivided into four replications, on farther away from the spray r ~ o ~ z l tch,e re is less which the four harvesting methods were used. chancc of the spray drift getting on him. The spray Treatment plots of 120 m2 were randomized following tank is carried on two hicyclc wheels, reducing the the randomized complete block statistical design. load the operator carries and the possibility that he The cowpea variety used in this experiment was 1T- may spill spray mixture on himself. X2E~9, an upright, early maturing variety. The The sprayer uses a 15-1 pneumatic knapsack cowpea crop was fully dried a t harvest, with a seed sprayer (which is pressurized before use) with a moisture content of ahout 12%,. Measurements were pressure regulator on the outlet. made of the harvesting rate, harvesting losses, The pressure regulator allows for constant threshing rate, threshing losses, impurities, seed pressure on the nozzles as long as the tank pressure is damage caused hy threshing, moisture content and above the set pressure. Four low-vnlume flood jet. total yield. nozzles were used that apply approximately 70 ljha a t Because the test field had a very uneven surface. a walking rate of 3.5 kph. The sprayer was used on the cutter bar had to he set a t 10 cm rather than 5 cm. areas where old row stubble could still be seen, so the which could have caused fewer losses in treatments 3 operation could he done without markers. and 4. With cutting and windrowing, most losses can The effective field capacity wi th water and he avoided because the person harvesting picks up chemicals a t the side of the field was 1.67 li/hn. The plants that have fallen over. With manual pod theoretical field capacity is0.7 h/ha a t a walking rate picking, the harvesting rate was very slow because of 3.5 kph. The time spent filling the sprayer and adding one chemical was 5 min per 15-1 tank. I t t,ook 4.5 tanks/ha and a total of 25 min/ha t o fill the tank. Table 43. Effects of cutting height on yield and The sprayer appears t o have solved the problems harvest losses of upright and spreading mentioned above, although the volunle of water is cowpea varieties, IITA, 1981 still very high for areas where water must be carried Yield, Losses Dry mat- long distances. This sprayer does not reduce the Cutting height kg/ha k#/ha fcrcent ter, kg/ha difficulty of walking in straight lines or following the VITA-5 previous pass, and agitation of chemicals in the tank 0 to 6 cm . . . . . . . . 862.88 388.00 44.97 769.79 seems to he inadequate for suspended materials. 6 to l 0 c m . . . . . . . 706.00 390.45 55.31 434.88 The sprayer was used in a number of fields where it, 11 to 15 cm . . . . . . 817.79 566.67 69.29 308.67 could he compared t o a large, tractur-mounted hoom 04-0'67-IF sprayer applying the same rate of rhemicals. In 0 to 5 crn . . . . . . . . 794.21 104.88 13.31 1,167.1'2 generill, it controlled weeds as well as the tractor- 6 to 10cm . . . . . . . 807.55 284.00 35.17 44~ 4.8- 8 mounted sprayer, hut further work needs to be done 11 to 15cm . . . . . . 959.55 499.12 52.02 325.33 before any definite con<:lusionsc an be d r a w n . N.C. Note: The combine was ope~.;rteda t low speed (0.50 mlsec or 4.93 Nauasero to 7.41 hr/ha). Farming Systems 167 Tahle 44. Comparison of four cnwpea harvesting methods, IITA, 1982 T~ ntal iiet yield," Itatc, man-hr/ha Losses, kyjha yield.h Harvesting method kg/ha Harvesting Threshing Total Harvesting Threshing Total kgiha Manual picking . . . . . . . . . . . . . . . . . . . 2,021 451 12 463 47 3'2 79 1.942 Plant harvesting and windrowing.. . . 2,201 124 33 157 54 152 206 1.995 Cutting by one-row cutter bar . . . . . . . 2,023 81 24 105 426 I93 619 1.104 On<,-rowr ornhinr harvester.. . . . . . . . 1.983 37 43 43 512 229 741 1,242 Note: Grain moisture contrnt at harvest was 12.0%,. 'lTolai yicld includrs harvcsting and threshing losses. hNrt yield is total yield minus total losses caused hy hs~rvestinga nd th the harvesters were trying to avoid leaving any pods beginning of a planting season long after the forest in the field. was cleared. There are strong indications that mechanization In 1982 a series of experiments was carried out in increases losses and that manual cutting and the West Bank area a t IITA to evaluate a low- windrowing are more cfficient. Losses are inevitahle horsepower, four-wheel tractor for its usefulness in when a cutter bar is used for harvesting. Tahle 44 no~ti lfla rming under tropical ficld conditions and to shows that yields ti.om ;rll trials were uniform. The improve the design of the IlTA farmohile, test its data on losses and labor show an inverse pro- performance on relatively large fields and evaluate portional relationship with mechanized harvesting. its operational and economic ef%icient:y.A four-wheel Manual treatments 1 and 2 had minimum losses of Massey Fcrguson 210 tractor of 15 kW (20 hpj was 0.57 kg (2.35% of the yield) and0.65 kg '.46%,j, while mounted with a six-row rolling injection planter and mechanized treatments 3 and 4 had losses of 5.12 kg a 3 ~ mb ox fertilizer applicator pulled behind the (21.09'jb) and 6.15 kg (25.84%). Nevertheless, planters. For spraying the tractor was equipped with harvesting with the cutter bar is significantly faster a PTO-driven, 8-m boom sprayer using a 375-1 tank. than manual picking. Harvesting and threshing with Spraying had to be done in separate preplant and the combine was fastest, followed by the one~row preemergence operations. During these operations, cutter bar, and plant harvesting and windrowing. the tractor driver was guided by marking poles. Manual picking was the slowest of the harvesting The IITA farmobile consists of a 4.85-kW (6.5-hp). methods evaluated. The net returns of the Sour t.wo-wheel tractor with a trailer and a tool bar harvesting methods was calculated based on the net carrying a four-row rolling injection planter yield in kilograms per hectare (Table 45). The market attached to the hitchbar of the trailer. It also carries price of 1k g of cowpeas was $1.50, and the labor cost a 4-m boom sprayer powered by a pneumatic was $0.75 a t harvest. The returns of harvesting knapsack sprayer and a centr ifugal fertilizer methods 3 and 4 were sharply reduced hecause of spreader powered by the tire of the trailer. excessive harvesting losses.-N.C. Nauasero Both types of farm equipment were used on no-till fields of first season maize and second season Evaluation of Low-Horsepower cowpeas. The four-wheel tractor was used on ahout Equipment 15 ha and the farmobile on ahout 10 ha. Before planting of the second season crop, some of the plots On land cleared hy hand according to traditional were sprayed with desiccants and then mowed. The methods (which usually leave large stumps protrud- crops wcrc harvested manually. The data in Tahle 46 ing fiom the ground), mechanical planting under a show that the four-wheel, 15-kW tractor had an no-till system is extremely difficult. I t is almost effective field capacity (amount of' land covered impossible t o use four-wheel tractors with con- ventional planters because of the high stumps, Tahle 45. Harvestin-e and threshing.> r eturns of four uneven surfaces and clustered roots in these fields. cowpea harvesting methods, IITA, 1982 When a tropical forest is cleared mechanically with a Ket tree pusher and root rake, it, is left with partially Total return filled stump holes and is unprotected from erosion. Net Market labor, Labor after Clearing with a shear hlade (Rome KG Blade) leaves Harvesting yield, value, man- cost labor, large stumps cut off a t ground level, which can method kg/ha $150/kg hr/ha $.75/ha $!ha severely damage planting equipment. Manual pod Appropriate farm machinery for these systems p~cking.. . . . . . 1,942 2,913.00 468 317.25 2,565.75 should be narrow, light and maneuverahle so tha t i t Plant harvesting can operate around or over stumps and holes. and windrowing 1,995 2,992.50 157 117.75 2,814.75 Planters must have the capacity t o penetrate Cutting by one- through thick mulch left on the soil surface after row cutter bar. . 1.404 2.106.00 105 78.75 2.027.25 hush clearing and through very hard soils. The heavy One-row combine harvester.. . . . . 1.242 1,863.00 43 32.26 1,830.i5 regrowth of weeds and bush is often a problem a t the 168 Farming Systems during the total field time) of 0.72, 1.72 and 0.7 h/ha application was 0.5 h/ha (with a range of 0.41 to 0.13 for desiccant spraying, planting, fertilizing and h/ha) and for planting cowpeas 1.5 hjha (with a range preemergence spraying. respectively. The eEective of 1.13 to 2.07 h/ha). Its tieldcficiencv rangcdt'rom27 field capacity for herbicide application (desiccant or to 58'%, for planting and fertilizing maize, 33 to 60% preemergence) ranged fkom 0.46 to 1.09 h /ha and for for planting cnwpeas and 20 t,o 53% for herbicide planting/fertilizing, 1.17 to 2.53 h/ha in maize. When application. Ficld efficiency is the ratio of rffective planting cowpeas during the second season, the field capacity to theoretical field capacity expressed tractor 's egective field capacity for herhicide in percent. Theoretical capacity is the machine's rate of performance if i t performs its function 100'%,o f the l';~hlc.4 6. ( ' o ~ l ~ p ; ~ ~o.l'i;r o fi,u~t. -wI~t.t.I.1 3-k\V tt.;ic.tor. time a t the rated operating speed, using l00'%,o f its w i t h the ]IT.\ l ' ;~~ .~i~oi nb inlot-~ti ll ~ l ; ~ n t i n u nominal width. of maize and cowpeas, IITA, 1982 With the farmobile, it took about 2.2 h/ha to apply Eff'ectivc the preplant desiccant spray using the 4-m boom field capacity, I~r/ha Field efficiency,% sprayer. Planting, fertilizing and preemergence First Second First Second spraying were all done in the same pass over the field. season season season season Uuringplanting thespray boom was reduced to :imto maize cowpeas maize cowpeas match the width of the four-row planters, which were Four-wheel tractor set a t 0.75-m row spacing. A marking string was used Desiccant 0. 7 2 0.53 31.47 to guide the i'armohile during these operat,ions. spraying . . . . i 0.16 f_ 0.12 4 6.6 42.6 The effective field capacity of the farmobile for I'lantingl 1.72 1.5 43.2 planting, fertilizing and spraying in maize was 5.98 fert. . . . . . . . . 5 0.51 i 0.35 ? 11.7 47.0 h/ha (with a range of 5.03 to 7.78 h/ha) and for Preemerg. 0.70 0.52 33.44 planting and spraying in cowpeas, 3.87 h/ha (3.08 to spraying . . . . 20 .21 2 i 8 . 8 42. li 4.41 h/ha). The field efficiency of the farmobile in Total mach. planting maize was 20%. in planting cowpeas 27% hr./ha . . . . . . . 3.14 2.55 and in spraying 25%). Farmobile In test,s over thc 1;ist three years, the improved llesiccant prototype of the farmobile has heen found to have a spraying". . . . 2.20 25.0 number of advantages. The more expensive, two- Plant.j fert. 5.98 ,'3.87 wheel walking tractor with steering clutches. spraying . . . i 1.27 i 0.57 20.0 27.0 Total mach. instead of a fixed axle. has removed the helt-clutch hr/ha . . . . . . . 8.18 problem and greatly improved operational efficiency. The row string marking device has proven to he "Drsiccirnt spraying was clone with different cquipmcnt dur inR faster andmore accurate thansighting poles. Putting thr second season. larger wheels on t,he trailer has reduced the rolling l':nhlc~. 47. K C < B I I ~ I I Iin~dCi (.jators ol':~nlI 'l'.\ ftarnia~l~ilv resistance and improved the lateral stability of the ; ~ n df'o tu-whct.1. I>-k\$'ct.;lrtor firr no-till farmohile. The centrifugal fertilizer spreader planting of maize and cowpeas, IITA, 1982 powered by the tire of the trailer has enabled the Four- operator to plant. spray and fertilize simultaneously. wheel, The potential economic henefits of' using either of Far- 15-kW these two small tractors in no-till planting of maize F,conomic indicator mobile tractor and cowpeas depends largely upon the tractor's Avt., effective field caoacitv. hrlha effective field capacity and efficiency. t,he initial For plantinglfrrt. and spraying . . . 4.9 1.62 investment and operation and maintenance costs, For desiccant or preernrrg. spraying.. . 2.22 0.71 and its reliability and economic life. Some of these Avg. ficld efficiencyf br: economic indicators are presented in Table 47. Planting, . . . . . . . . . . . . . . . . . . . . . . . . 22.5 45.0 Considering the quantity of inputs used per field, Spraying, % . . . . . . . . . . . . . . . . . . . . . . . . 25.0 30.3 the four-wheel tractor was more eflicient than the Scale uf operation, ha per season farmobile probably because ot' its greater operating First season maize . . . . . . . . . . . . . . . . . . 15-20 32-~:35 speed. The potential area of opcrations for the Second season maize or crrwpeas . . . . . . 10 22 Efficiency of' input use, %, farmobile was estimated by the critical path method Chemicals. . . . . . . . . . . . . . . . . . . . . . . . . . 70-90 8 7 95 to he 15 to 20 ha during the first season and 10 ha l'rrtilizers . . . . . . . . . . . . . . . . . . . . . . . . . . 94 75 during the second. For thc four-wheel tractor, the Maizcsecd . . . . . . . . . . . . . . . . . . . . . . . . . 86 78 area was estimated to he 32 to 35 ha during the first Cowpei~s eed . . . . . . . . . . . . . . . . . . . . . . . 83 75 season and 22 ha during the second. The area of Initial cost of'e quipment and its operation was smallcr in the second season because attachments in dollars. . . . . . . . . . . . . . . 10.200 28.050 the first season crop was harvested manually and the Pay bark period, years. . . . . . . . . . . . . . . . . 2 3 rainy period of the second season was short. During West Bank net benefits in dollars . . . . . . . 7.524 7.981.28 manual harvesting of maize and cowpeas, experien- Enterprise net henefit per hectare ced farmers were employed on a daily task basis. ~ c arnn um in dollars . . . . . . . . . . . . . . . . 855 554.25 Harvesting of maize took 9 man-d;lys/ha, and cowpea harvesting took 22 man-days/ha. Given the size of the In assessing t he suitability of these small tractors. a rea of operation, the farmobile operator needs 135 t o i t is important t o examine t he factors that afi'ect their 180 man-days (or 5 t o 6 workers) t,o harvest maize and field efficiency. As shown in Tahle 50, t h r four-wheeL 220 man-days for cowpeas. The four-wheel t ractor tractor spent 45'%, of i ts ficld t ime actually working. operator needs 288 t o 315 man-days (or 9 t o 11 while the farmobile spent only 22'%:, of the time workers) t o harvest maize and 484 man-days for working. Interruptions during planting with the cowpeas. four-wheel t.ractor took 49.5'%, of ficld time and 73',!(, The activit,ics considered in t he critical path with t he farmobile. analysis were procuring inputs. preparation of the The results of these experiments indicate that low tractor , procuring water for spraying, desiccant horsepower t ractors are mech;inically and economi~ spraying, planting, fertilizing and preemergence cally suitable for no-till farming in the tropical forest spraying, employing of workers for manual harvest- zone. Their initial investment costs of $10,200 to ing and the harvesting itself, and transportat,ion of $25,050 may be within t he reach of a large number of produce from the field. farmers i n developing countr ies , especially if T h e in i t i a l cos t s of t h e equipment a n d i t s reasonable farm credit i s availablc. The pay back attachments are $10,20Ofor the farmobile and $28,050 period is only two t o th ree years. With one of these for the four-wheel tractor. The maintenance and tractors, a small farmer rould increase the area interest o n capital costs over the farmobile's ex- cropped from 1 o r 2 ha t o over 15 h a for the first and pected economic life of five years were estimated t o second seasons of each year, provided tha t inputs and be $7,941 and for the fc~ur-wheetlr actor $21,838.50. sufficient labor a r e available a t harvesttime. This From a budget analysis (with a farm size of 10 h a for analysis also shows t he importance of having more the farmobile and 15 ha for the tractor), the payback efficient harvesting procedures o r equipment to period was estimated t o be two years for t he reduce the l i kc l i ho~~odf labor shortages a t the end of farmobile and three years for t he four-wheel tractor. each season. After one year's fixed and operational costs and The farmobile can be economical for small farmers labor. chemical, fertilizer, seed, transportation and since i t enables them to operate a 10 h a farm very bagging costs, t he ne t benefit obtained from the conveniently. obtain a net benefit of about $857 per farmobile per hectare per annum was $857 and from hectare per annum and recover the initial invcstment t he four-wheel tractor $555 (Tables 48 and 49). capital in about two years. However, t he low- Table 48. Partial budget for a n IITA farmobile Table 49. Partial budget for a low-horsepower tractor Costs Dollars Costs Dollars 1:ixed costs Fixed costs Depreciation at 20%, per annum. . . . . . . . . . . . 2,040 Depreciation at 20'jb per. annum . . . . . . . . . . . . . . 5,610 lntercst on investment at ll'i:, of $10,200 . . . . 1,122 Interest on investment a t I I%, of $28.050. . . . . . . :],OX5 Operational costs Operational rosts Repairs and maintenance at 15'y0 ppcr annum. 1,020 Repairs and maintenance a t 15'j: per annum . . . 4,208 l'uol consumption for I17 hr at 0.6 I/hr . . . . . . 14 Fuel consumption for 82.81 hr at 0.9 l/hr . . . . . . . 14 Operator's labor, two persons Operator's labor, two persons for 117 hrs at $3.54 . . . . . . . . . . . . . . . . . . . . . 414 forX'2.81h r a t $3.54 . . . . . . . . . . . . . . . . . . . . . . . 293 Variable costs of farm inputs Variable costs of farm inputs Prcpldnt and preemergence herbicides. . . . . . 3,076 Preplant and precmergence herbicides . . . . 4.533 Insecticides for cowpeas . . . . . . . . . . . . . . . . . . 939 Insecticides for cowpeas. . . . . . . . . . . . . . . . . . . . . 1,406 Fertilizers for maize. . . . . . . . . . . . . . . . . . . . . . 2,886 Fertilizers for maize . . . . . . . . . . . . . . . . . . . . . . . . 4,966 Labor for supplementary weeding in cowpeas 568 Labor for supplementary weeding in cowpeas . . 635 .Mowing before second season crop . . . . . . . . . 354 Mowing before second seasun crop. . . . . . . . . . . . 636 Labor for manual harvest.ing of maize, Labor fbr manual harvesting of maize, 79.2 man-days at. $6.24 . . . . . . . . . . . . . . . . . . 494 129.6 man-days at $6.24. . . . . . . . . . . . . . . . . . . . 809 Labor for manual harvesting of cowpeas, Labor for manual harvesting of cowpeas. 193.6 man-days at $6.24 . . . . . . . . . . . . . . . . . 1,299 314.62 man-days at $624. . . . . . . . . . . . . . . . . . . . 1.96:i Transportation, shelling and bagging. . . . . . . 600 Transportation. shelling and bagging . . . . . . . . . 1.002 Maize seed. 1% kg at $0.375 . . . . . . . . . . . . . . . 73 Maize secd, 417 kg at $0.376. . . . . . . . . . . . . . . . . . 156 Cowpea seed, 157.5 kg at $1.61 . . . . . . . . . . . . . __24 2 Cowpea seed, 280 k g at $1.61 . . . . . . . . . . . . . . . . .3 Total expenditure. . . . . . . . . . . . . . . . . . . . . . . . . . 15,141 Total expenditure . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 9.765 Revenues Revenues Revenue fiom maize harvest (first Revenue from maize harvest (first season), 40.1 t a t $376.. . . . . . . . . . . . . . . . . . 15,037.50 season), 66.8 t a t $375 . . . . . . . . . . . . . . . . . . . . . . . 25,050 Revenue from cowpea harvest (second Revenue from cowpea harvest (second season), 5.037 t a t $1,500 . . . . . . . . . . . . . . . . . . 7,55550 season), 8.47 t at $1,500 . . . . . . . . . . . . . . . . . . . . . . Total rcvenue . . . . . . . . . . . . . . . . . . . . . . . . 22.593.00 Total revenue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37,755 Net hcnefit. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,452.00 Net benefit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,990 Net benefit per hectare . . . . . . . . . . . . . . . . . . . . 857.00 Net benefit per hectare. . . . . . . . . . . . . . . . . . . . . . . . 565 170 Farming Systems Table 50. Activities affecting field efficiency of a four- seasons a t planting, weeding and flowering, leucaena wheel, 15-kW tractor and IITA Farmobile, tops were pruned, weighed and returned as mulch to IITA, 1982 the crop. Average time spent as a The herbicide plots were sprayed with paraquat percentage of field time and atrazine for maize and paraquat and dual for Four-wheel cowpeas. The cowpea crop received four insecticide Activity l.5.kW tractor Farmobile applications to control thrips, aphids, Maruca and Turning pod bugs. The control plots were weeded each season Spraying . . . . . . . . . . . . . . . . . . 9.0 with a hoe two weeks after planting. All plots were With planters.. . . . . . . . . . . . . 15.0 10.0 planted to maize or cowpeas without tillage and were Materials handling top-dressed with P and K fertilizers during the first Seed . . . . . . . . . . . . . . . . . . . . . 7.2 5.0 season only. To obtain realistic labor input data, Fertilizers . . . . . . . . . . . . . . . . . 8.6 6.0 casual workers with some farming experience were Chemicals and water. . . . . 16.0 13.0 Machine adjustments . . . . . . . . . hired on a daily task work basis. This resulted in 6.0 10.0 Clraning up clogged more efficient labor inputs than in the previous year. spray nozzles. . . . . . . . . . . . . . . 6.3 9.06 Uuring the first season, the cutting of leucaena String mnrkcr adjustment ..... 8.9 4.75 regrowth and pruning of shoots took 16.46,14.6 and Removing trash and cleaning 7.5 man-days/ha or a tot,al of 38.56 man-dayslha. In clogged plant.ers. . . . . . . . . . . . 3.8 1.2 the second season, these activities required 16.2, 7.5 Traveling around ohstacles, and 6.9 or a total of 30.6 man-dayslha. I t thus took an ditches. ctc.. . . . . . . . . . . . . . . . - 2.0 average of 16.3 man-days/ha for cutting and 9.1 man- Olher field interruptions . . . . . . 12.0 days/ha per pruning, compared to 30 to 24 man- Total no. ofintcrruptions days/ha in the previous year for cutting and one During spraying.. . . . . . . . . . 46.2 - During planting. . . . . . . . . . . . 49.5 73.0 pruning of leucaena stems after the plots had been under fallow for one year. The leucaena treatments this year increased labor horsepower tractor needs further improvement and costs by only 32%,, and leucaena-nitrogen increased must be tested on farmers' fields. The various them by 34%, about 20'%, less than the increase of the mechanical components of each tractor, especially previous year (Table 51). Rut the herbicide com- the farmobile, also require further development. At ponent in the leucaena plots reduced labor inputs present handling of chemicals and the spray nozzle by 19.97%. so that leucaena-herbicide actually in- system unnecessarily reduce fielc efficiency.-~ creased labor costs by only 12% and leucaena- C. Garman. L1.S. Ngambeki and N.C. Navasero nitrogen-herbicide by only 14'%,. As in the previous year, nit,rogen increased lahor costs by less than Production Economics lo"/,, while herbicide-nitrogen and herbicide alone reduced labor costs by over 20%. The total nitrogen Alley Cropping Leucaena/Maize/Cowpeas contribution fiom three prunings of leucaena was about 145 kg N per hectare per season. However, Agronoeconomic studies on alley cropping of the purchase of chemicals such as nitrogen and Leucaenu leucocephala with maize followed by herbicides a t unsubsidized prices caused the cowpeas were continued a t IITA in 1982. The Ieucaena-herbicide t reatment t o increase total objectives of these studies were (1) to monitor labor production costs by 40.49;', ha, leucaena-nitrogen- and other inputs and determine the economics of the herbicide hy 48.84%, and leucaena-nitrogen by system, (2) t o assess the effects of alley cropping with 44.87%, compared to leucaena alone, which in- leucaena on maize and cowpea yields, and (3) to creased total production costs by only 36.4%. check the 1981 findings that there is a negative As shown in Table 51, leucaena increased maize interaction between leucaena and nitrogen and that yields by 45'16 (982 kglha), leucaena-nitrogen by 48% leucaena can increase farm profits by as much as (1,047 kg/ha), leucaena-herbicide by 69%, (1,501 30%,, even though Ieucaena stands occupy 20%, of t.he kg/ha), and leucaena-nitrogen-herbicide by 118% land and the pruning increases lahor costs by ahout (2,549 kg/ha), compared to the yield (2,159 kg/ha) of 50'%,. This is double the profits from nitrogen and the control plots. The nitrogen treatment increased ahout 20%, more than those from either leucaena- yield by 33% (713 kg/ha) and herbicide-nitrogen by nitrogen or leucacna-herbicide. 40%) (862 kg/ha). First season maize and second season cowpeas In cowpeas herbicide alone and leucaena-herbicide were grown in a trial with four replications on a plot gave yields of 745 and 730 kg/ha, respectively, an that had produced two successive crops of maize in increase of 19.58 and 17.17%, compared to the yield 1981. 1,eucaen;r and herbicides were the main plot (623 kg/ha) of the control plots. But the leucaena treatments, and in the first season maize, a suhplot treatment by itself appeared to depress cowpea yields treatment of nit,rogen a t 80 kg/ba was superimposed drastically. The main effects of leucaena on maize on these. No nitrogen was applied to the cowpeas yield were significant a t the l'z, level and greater during the sct:ond season. During each of these than those of nitrogen and herbicide. The main effect 0 Table 51. Data on yields and labor costs in an alley cropping experiment, LLTA, 198" First season maiec Second season cowppns ~ +incrva~si. ~ ~ ~ t Grain Percent yield Grain Pcrcent yicld i l l lahrn.., a 2.5'%, of the plot, while the remaining half received only premium is paid for white maize over yellow. one Cymbush application. All other conditions were In the southern states of Nigeria, mai7.e is one of typical for that area. the major constituents of the rural diet. Harvesting Table 5 3 gives the yields, ne t benefits and of green maize cobs (not fully mature) during the benefitlcost ratios of insect management for different months of May to July was a common practice among Table 53. Net benefit of minimum pest management in cowpeas, 1982 Yield. kg/ha Net No Three Yicld Value of yield Inneased spray- benefit, Benefit: Variety spl.aya sprays increase increase, $/hah ing cost. $/ha $/ha cost ratio Nigcr State Local . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 113 113 127.50 120.00 7.50 1.1 TVx 3236.. . . . . . . . . . . . . . . . . . . . . . . . . 13 1,223 1,210 1,362.00 120.(10 1,242.00 11.4 TVx 3516.. . . . . . . . . . . . . . . . . . . . . . . . . 40 920 880 990.00 120.00 870.00 8.3 TVx4262 . . . . . . . . . . . . . . . . . . . . . . . . . . 26 522 496 558.00 120.00 438.00 4.7 Kwara State Semi-improved . . . . . . . . . . . . . . . . .., . . 80 570 490 562.00 127.50 424.50 4.3 Ife Brown . . . . . . . . . . . . . . . . . . . . . . . . . 77 740 663 745.50 127.50 613.00 5.8 TVx3236 . . . . . . . . . . . . . . . . . . . . . . . . . . 118 918 800 900.00 127.50 772.50 7.1 *The treatments in Kwara State were one spras and four sprays. "Increased yirld was valued at a net market price of $l.IZS/kp after deducting the harvesting and marketing cost of $0375/kg b'arming Systems 173 all farmers. The importance of fresh maize is tha t i t fallows and shifting cultivation still dominate. Land helps overcome food shortages early in the season clearing and land preparation in these systems are and serves as a source of cash income through the usually the most lahor demanding activities, for market . Maize is consumed in different food which several forms of communal lahor organization preparations, the most common among them being and group action have been developed in traditional boiled or roasted snacks, custard or porridge for agricultural production systems. In group farming breakfast. Maize flour is made into a variety of dishes the production process on a common farm is under for lunch and dinner. Rural families reported that in group organization and management. With the a year they consumed a n average of more than 200 promotion of cooperatives, group farming has also meal servings made from maize. attracted increasing attention as a means of over- Storage of' maize is a major problem in the humid coming the limitat,ions of' small-holder production. zone. Because of high grain losses in storage, maize is Statistics appear to indicate that the numher of consumed over only a few months as farmers attempt farmer organizations with group farms is increasing, to dispose of their crop soon after harvesting. Most hut information on performance a t the village level is farmers store maize on cobs inside the kitchen by still scarce. either placing them on racks or hanging them in A survey was made of 87 group farms and co- baskets tied to the ceiling to keep them dry and free operatives in 10 states in Nigeria through 87 group from weevil attack. Since only a limited quantity of interviews and 294 individuzrl interviews of members maize can be stored locally, a further increase in of 10 farmers' groups. These farms, under co- maize production in the forest zone of Nigeria would operative or group management, were located in he difficult to achieve without more reliable, cheap three agroecological zones of Nigeria. The survey seed sources. was based on a general questionnaire on group performance and on individual interviews along Cowpea Production on Small Farms preestahlished guidelines. The study was done with About 25%,o f the 168farmers surveyed in the medium the cooperation of officers of the Nigerian Federal and high rainfall forest zones of southern Nigeria Depzrrtment of Agricul tural Cooperatives and were growing cowpeas in mixtures with maize, yams, selected students of the Federal Cooperative College cassava and/or vegetables. The remaining 75';6 had at Ibadan. The survey included farmers' groups in the given up growing cowpeas because of the high risk of following states: Anambra, Rendel, Rorno, Cross crop failure resulting from insect pests. Those still River, Gongola, Imo, Kaduna, Kwara, Lagos, Ogun, growing cowpeas had, on the average, one plot in Ondo, Oyo and Sokoto. cowpeas of a local indeterminate variety, which was manually harvested by women and children three to General Group Characteristics six times a season. The average size of the cooperatives and farmers' Consumer preference for cowpea varieties varied groups was 65 members with large variation. Only according to location and was guided by traditional about 149: of the members were women, even though tribal preferences. In the 40 villages surveyed, two 85% of the associations reported female members. general cowpea types, oE-white and light brown, Surprisingly, 70%) of t he membership was under 45 were grown and eaten. years of age, which is contrary to the usual age Among those who grew cowpcas, nearly 20%, used structure in the rural areas of Nigeria. This would the leaves and green pods as fresh food. From the dry seem to indicate t,hat cooperative and group farming beans, a variety of food dishes and snack foods were are of special interest to younger farmers. Farmers' prepared, both for family consumption and for selling associations must reach a certain size t o assure their to neighboring families. A large majority of farm long-term survival. About one-third of the groups families consume cowpeas year-round, with a n reported a stable or slightly declining membership, average of two cowpea meals per week. Many whereas the rest reported a steady increase in size. farmers, whether producers or not, purchase dry cowpeas for family consumption. Farmers report no Availability of Land and Labor difficulties in marketing their cowpeas. Storage losses from weevil attack, however, pose Very few groups had problems gaining access to land. serious problems, particularly in the high rainfall The average farm size was 109 ha, of which 69 h a was regions. Farmers store cowpeas both as unthreshed cultivated and the rest kept in fallow reserve. pods and as threshed beans in their kitchens, where Cultivated land averaged 0.86 ha per member, not far smoke reduces weevil attacks. Still, farmers reported from the average small holder's cultivated acreage in storage losses of up to 12 to 15%,w ithin a four- to five- many parts of Nigeria. month storage period.-M. Ashraf Less than half (41%,) of the organized farmers had access to tractor services. One group owned a Cooperatives and Group Farms tractor, 3 hired one from private sources, and 33 used the tractor services of public institutions. West African farming is based mainly on manual Table 54 shows the major energy sources of the labor in small-holder systems in which rotational farms. The tractor appears t o he the only one that 174 Farming Systems correlates clearly with farm size. The manual labor initiative is generally listed as the most important input from group or hired sources is very similar for reason, i t is clear that other underlying factors have all threesize categories. This appears to indicate that resulted in their joining.. Of these family influence, organizational factors and qualitative criteria for cooperative officers and radio are the most important group functioning should be considered. Fifty-three factors. percent of the organization hired manual labor. Nearly all included bush clearing and land prepar- Cropping Systems ation in their regular schedules. One,quarter of the Eighty-five percent of the farmers grew two or more tractor users did their land clearing manually by crops in any one season. Most frequently (46%) they hired labor. The 294 individual interviews showed grew two crops. Cassava and maize were the most that only half of the members worked regularly on common combination, being grown on about half of their group's f'arm; the others either sent a hired the farms, together with yams, rice, and various laborer as a replacement or gave monetary compen- vegetables, whenever more than two crops were sation. Table 55 gives a hreakdown of the motivations grown. Table 56 gives the frequencies with which for joining as related to the members' labor inputs. group farms and individual members produce a wide The members were asked to give two reasons for range of crops for marketing and for subsistence. having joined the association. Although their own Marketing and Income Table 54. Size distribution and labor sources of group Most of the production from the farms was sold, and farms in Nigeria, 1982 only a small part was distributed to members. The Amount of average sales per group f'arm during 1981-82 were cultivated land per member reported to be $11,842.50, or $174.50 per member. 0.5 ha 0.6 to More Total Surprisingly, tbis amount of sales income from group Labor sources or less 1.0 ha than 1 ha sample activities stands in stark contrast with the average Tractor and group percent sales by memhers from their own ~ r i v a t per oduction members . . . . . . . . 19 19 39 25 units. The 294 individual interviews indicated an Tractor, group and average sale of about $1,800 from their own private hired labor . . . . . . 16 19 22 19 Tractor and mainly l a ~ ~ dins 1981~82 (excluding one group farm in hired labor . . . . - 5 5 2 Sokoto, where members sold a n average of $42,000 Manual work done from their own land). The individual sales included a by group only.. . . 24 19 23 22 much broader range of crops, and regional difler- hlanual work done ences were rather marked. Figure 35 shows the by group and distribution of sales income by crops for the three hired labor . . . . . . 30 29 5 22 major regions of Nigeria, derived from the individual Manual work done interviews, and for 69 group farms. mainly by hired The reasons for the disparity between individual labor . . . . . . . . . . . 2 9 9 10 100 100 100 100 and cooperative farm sales are unclear. I t is ohvious All tractor users . . . 35 43 65 16 that farmers join groups only as a sort of sideline to Groups doing their own private agricultural activities and not as manual labor an attempt to improve their income by increasing only . . . . . . . . . . . . 65 57 35 54 their efficiency through associated forms of pro^ n = 37 n = 21 n = 2,'3 n = RI duct ion. P .A ?, P. Manson and G. Cesari~li Table 55. Members'reasons for joining group farms in Nigeria, 1982 Technology Transfer and Members not Members work- working regu- Training ing regularly larly or at all Ileason for joining First Second First Second The Methodology of On-Farm group farm reason reason reason reason Adaptive Research PerCFnt Own initiative.. . . . . 65 ~. 85 On-Farm Adaptive Research (OE'AR) is a relatively Family decision . , . . 5 7 8 34 new way of approaching the adoption of new influence of chief. . . 12 6 2 1 technology by small farmers in the tropics. The Religious group. . . . . - 2 - - approach emphasizes the necessity of understanding Extension service. . . 10 5 1 5 more thoroughly farmers' needs, conditions, and Cooperative oficer. . 2 33 3 12 problems as a precondition for successful develop- Radio . . . . . . . . . . . . . 1 15 - ~ 2 Other group. . . . . . . . ment and introduction of innovations into small- - 2 - 13 Other or no answer . holder agriculture. I t also stresses the need for a high 0 ~1 - -33 100 100 100 100 degree of farmer involvement in the on-farm research and the importance of farmers' views of proposed Farming Syslenis 175 Table 56. Percentage of group farms and of members North West who also have their own farms growing certain crops in Nigeria, 1982 Group Individual Crop farms farmers Cereals Maize . . . . . . . . . . . . . . . . . . . . . . . . . . . . I" 80 Rice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 27 Guineatarn . . . . . . . . . . . . . . . . . . . . . . 14 41 Millet . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 41 Tubers Cassava . . . . . . . . . . . . . . . . . . . . . . . . . . 59 77 Yams . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 14 C:ocoyams . . . . . . . . . . . . . . . . . . . . . . . . 4 44 East Gmup farms Swcet potatoes. . . . . . . . . . . . . . . . . . . . 1 35 Trees Oil palms. . . . . . . . . . . . . . . . . . . . . . . . . 6 30 Plantains . . . . . . . . . . . . . . . . . . . . . . . . . 6 29 Cocoa . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 16 Oranges . . . . . . . . . . . . . . . . . . . . . . . . . . 4" 54 Bananas . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Mangos . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Guava . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Pawpaw. . . . . . . . . . . . . . . . . . . . . . . . . . 28 Cashews . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Cola nuts. . . . . . . . . . . . . . . . . . . . . . . . . 16 Figure 35. Proportion of crops contrihuting to the total Shear butter . . . . . . . . . . . . . . . . . . . . . . fi product sales by individual farmers in thrce regions of Hitter cola. . . . . . . . . . . . . . . . . . . . . . . . 5 Nigeria and hy Nigerian group farms. 1981 82. African mangos . . . . . . . . . . . . . . . . . . . 5 Coffee . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 the Ford Foundation t o broaden i ts research Breadfruit . . . . . . . . . . . . . . . . . . . . . . . . 4 capability by creating a new project within its Others . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Farming Systems Program. The objectives of this Vegetables project are to further develop on-farm adaptive Melons . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 32 Okra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 78 research methodologies that are suitable to West Leaf vegetables. . . . . . . . . . . . . . . . . . . . 5 36 African conditions, t o assist national research Peppers . . . . . . . . . . . . . . . . . . . . . . . . . . 3" 26 institutions in West African countries in developing Tomatoes . . . . . . . . . . . . . . . . . . . . . . . . . 1" 45 OFAR capabilities and applying the results of this Pumpkins . . . . . . . . . . . . . . . . . . . . . . . . 18 research in their countries, and to set up courses in Onions . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 various West African countries and a t IITA, for the Lcgumes staff'of West African research institutions. Cowpeas . . . . . . . . . . . . . . . . . . . . . . . . . 2 18 Because of the present lack of broad experience in Beans . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 OFAR in West Africa and a t IITA, methodology Soybeans . . . . . . . . . . . . . . . . . . . . . . . . . 1 Pigconpeas . . . . . . . . . . . . . . . . . . . . . . development and training will initially go hand in 9 Lima beans . . . . . . . . . . . . . . . . . . . . . . . 4 hand. Scientists with an interest in on-farm adaptive Special crops research have been identified in national research Pineapples . . . . . . . . . . . . . . . . . . . . . . . . 4 14 institutes in Nigeria, Ivory Coast and Cameroon and Leaves for food wrapping. . . . . . . . . . . 10 will be participating in planning meetings and a Leaves for cola packing . . . . . . . . . . . . 3 training workshop a t IITA, where a format for a West Tobacco . . . . . . . . . . . . . . . . . . . . . . . . . . 4 African methodology will he developed in detail. Others . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 In June IITA organized a workshop on on-farm Note: These data were gathered in 87 group and 294 individ~ial experimentation tha t was attended by a large interviews. number of scientists with wide experience in OFAR. =Planned for 1983. They reached a consensus on the basic elements needed in OFAR programs and produced the innovations. In order for this approach to be framework for IITA's own approach to on-farm implemented effectively, the development of specific adaptive research. OFAR procedures is indispensahle. A second workshop was held a t IITA in November As reported last year, the Farming Systems 1982 with participants from national and inter- Program has set out t o develop effective OFAR national research and development institutions. I t methodologies for West Africa through a new pilot resulted in the creation of a West African farming project in areas of Nigeria i n cooperation with the systems research network. The objectives of this agricultural development projects (ADPs) financed network are to "create links between individuals and by the World Rank. IITA also received a grant from institutions, interested in a common approach in 176 Farming Systems farming systems research, t o establish a steady How areas. With the s tar t of the rains in May and June, of informat,ion on methods and approaches, and to farmers first plant their upland crops to ensure that coordinate and facilitate training erorts." A steering they will mature before the rains stop in October. committee and several working groups were set up to Planting on fadama land is usually delayed and carry out specific short-term and long-term tasks, incomplete and requires a large labor input for such as t o survey on-going farming systems research ridging the land by hand. Easing this labor con- and training facilities in the region, to make an straint in the months of July and August would inventory of terminology. definitions and taxonomy increase the area of rice cultivated, increase the yield of farming systems research, to establish a docu- through more timely planting, and lessen the risk of mentation center and publish newsletters, t o study failure. The means of doing so could be to change the the "zonification" of farming systems in West Africa, land preparation method from ridged seedbeds to flat and to organize a technical workshop in 1983.- cultivation, which besides saving labor, would also H.J. W. Mulsaers be more appropriate for the newly expanded tractor hire services and for the proposed chemical weed An Approach to On-Farm Adaptive control. The change from ridged to flat cultivation would Research also tie in with the work of the ADP on contour bunds The agricultural economics unit of t he Farming and permanent water control channels. This change Systems Program started an interdisciplinary on- would also make i t possible to raise short season farm research program this year for testing IITA catch crops on residual moisture, provided that the technology. The work is being carried out in Nigeria rice is planted early enough. This analysis illustrates with the Bida Agricultural Development Project. the use of a systems approach to matching pro- located in the Guinea savanna zone, and with the duction problems with potential improvements in the Ilorin ADP in the derived savanna zone. overall efficiency of a farming system. The next step The first step in the program was to review is to choose experimental variables and treatment information on land types, topographical features, levels. vegetation patterns and land use. In a socioeconomic Other factors limiting rice yields in the Bida ADP and agronomic survey of project farmers, infor- area were low stand density and iron toxicity, both of mation was collected on thc various agroecological which affect germination and seedling growth. The regions of Nigeria and on the farmers' main pro^ stand density was closely related to the ridged duction problems. seedbeds; wider spacing between ridges results in a The Bida region has two agroecological regions, low stand. Stands could be increased either by upland farmland dominated by dryland cereals and reducing the spaces between ridges or by planting on root crops and the lowland fadamas (small inland the flat. Thus, i n addition t o seedbed preparation, valleys), which are dominated by rice. Although the stand density was included as a test variable. upland and lowland fields are quite far apart, the Iron toxicity was a more difficult problem to deal same farmers till t he soil and raise crops in both. The with. One possible approach is to use varieties with upland crops are grown in various mixtures, while tolerance to iron toxicity. Other problems, such as rice is always n~onocropped. irregular water supplies and bird damage, were also The survey also found that the lowland rice area is encountered in the survey, but these are mostly further divided into two topographic sequences that outside the control of individual farmers. have different production problems. The slopes above A factorial design was chosen for agronomic rice the valley bottoms need short season drought trials, which included two treatment levels, one tolerant rice varieties, while the wetter, flat parts of being the level used by farmers and the other being the fadama require midseason variet ies with the level recommended by scientists. Only with the resistance to iron toxicity. The upland arcas can be variety factor were three cultivars included. The similarly divided according to cropping systems of three experimental variables, method of seedbed maize, sorghum and yam and of sorghum/millets. preparat ion, s t and density and var ie ty , were cassava, and groundnuts. combined in four experimental designs requiring In this first year our strategy was to produce the different levels of management. maximum amount of research information as quickly The first design consisted of fully replicated as possible for checking the suitability of available factorial experiments. They were in central loca t l' o ns technology, which can then be used in developing representing five agroecological niches within the recommendations for farmers. An assessment of the project area and were under the direct management best production possibilities showed that the rice of t,he project research staff. The second design crop and the fadama areas should be the major included two varieties rather than four. These research targets. experiment,^ were planted on a farmer's field with his The agronomic survey showed also that a high participation, especially in managing nontreatment demand for lahor in the planting season was the factors. In the third set of tests, t he stand density principal cause for under-utilization of fadama land, variable was eliminat,ed. leaving variety (at three despite the high potential productivity of these levels) and seedbed preparation (at two levels). These Farming Systems 177 tests were handled by farmers under the supervision Tn the Rida ADP, the on-farm adaptive research of the project extension staff. The fourth design was program quickly began to contribute to the de- the simplest of :ill, consisting of a single treatment velopment of close contact and cooperation between plot composed of all three factors a t the recom- the project's commercial. extension and research mended level. These plots were managed exclusively divisions. The contact point was the farmer, whose by the farmer, and his adjoining crop field provided progress is the best measure of success for all these the basis for comparison. divisions.-M Ashmf l imited on-farm research was also carried out on cowpeas, maize and cassava, mainly to generatemore information for a fut,ure research program in the Cooperative Development upland areas. The ohjectives of the cowpea agro- economic research were to evaluate minimum pest MIDAS Project in Ghana control and to explore the possibility of growing The Managed Inputs and Delivery of Agricultural cowpeas on residual moisture after harvesting the Services (MIDAS) Project, which ended this year and rice crop a t the beginning of the dry season. The was sponsored by the U.S. Agency for International maize and cassava trials assessed new cultivars for Development and the Government of Ghana, was their ability to withstand attack by the most common designed t o improve food crop production and insect pests and diseases. Unfortunately, the data increase the income of small farmers in the Brong- from these on-farm trials are not yet available but Ahafo region of Ghana. Small-farms systems re- will be reported next year. Some preliminary search, one of six components of the MIDAS Project. conclusions can be drawn, however, from the 1982 was carried out by IITA. The primary aim of this OFAR program on the selection of experimental research was to assist the government of Ghana in sites, on farmers' participation, and on lirikages developing. farming systems research capabilities in between projects. the Brong-Ahafo Region. Unless they stand to gain something, farmers are Owing to problems in building an access road and reluctant to offer their fields for trials that require other facilities a t the original research site, a new significant changes in crop management. Their location adjacent to the Atebubn Training Collegc reluctance probably stems from the high cost of land was chosen in early 1982. Several field trials were laid and seedbed preparation and from the risk involved out a t this new site, and some trials started in 1981 in making changes. This problem often can be solved were continued a t the old site. Some on-farm trials by choosing sites on community land, which have the were also conducted on farmers' fields during 1982. major advantage of involving the entire village community in t he implementation and demon- Alley Cropping with Leucaena stration of trials. Seeds of Leucaena leucocephala variety K-28 were Farmer participation proved to be essential to the drilled in continuous rows 4 m apart in April 1981 and establishment and maintenance ofresearch plots and were thinned to one plant every 40 to 50 cm in the to a correct assessment of farmers' reactions to row. A starter dose of 100 kg/ha of 15:15:15 fertilizer changes in crop management. Farmers usually pre- and 10 kg/ha of zinc sulphate was applied by banding. ferred to participate as a group so they could share In 1981 yams, maize and cowpeas were planted in the the burden of inputs and labor. Unless farmers were alley space, and the leucaena was allowed to grow paid, they tended to neglect the research plots. When without pruning. After one year the height of the trial plots offered tangible benefits (for example, leucaena was 261.4 + 32.9 cm; its circumference a t a when the researcher arranged and bore the cost,s of height of 1 m was 6.4 + 1.7 cm; and its approximate land preparation, fertilizers and pesticides), the dry leaf yield was 500 to 1,000 kg/ha per cutting. The farmers participated more readily. When assessing labor requirement for pruning was 50 t o 60 man- the results, the farmers proved to be very sharp hour/ha per cutting. observers of the rescarch plots. In the rice ex- This trial compared the performance of yam and periments, the farmers were particularly aware of the maize/cowpeas with and without leucaena hedge- tillering, crop growth, panicle size, grain color and rows 4 m apart. The main plots (20 m x 12 m) were grain size of the new varieties. divided into three subplots each with a different On-farm adaptive research evaluates technology fertilizer level. The experiment had a split-plot that can be adapted to local biophysical, social and design with four replications. The crops were to be marketing condition.., of farmers. To he relevant such rotated between plots in alternate years; that is, the research must set its priorities through a close plots that had yams in 1982 were to be planted with association with commercial and extension people maize/cowpeas and vice versa in 1983. Maize (La and farmers. I t must, take into consideration the Posta) was planted during the first season (April- inputs and services that can he provided as well as August 1982), followed hy cowpeas (VITA-5) in the the farmers' real needs. An extension service can second season (September-Novemher) in the maize/ achieve its goal of transferring new technology only cowpea plots; water yams (Dioscorea alata) were when i t is fully informed and farm inputs and services grown during both seasons. can be provided. The arrangement of the crops in four rep re^ 178 Farming Systems sentative main plots of one replication is shown in observation has also heen made in experiments at Figure 36. There were four rows of maize or cowpeas IITA. The leucaena stakes must be ringed to prevent in leucaena plots and five in plots without 1euc:xna. new leaf growth, which competes with the yam vines The spacing in cm was 80 x 25,80 x 15 and 200 x 200 for sunlight. Fertilizer response of yams was also for maize, cowpcas and yams, respectively. poor t o irregular. The low rainfall was undouhtedly 'rhc fresh tuher yields of water yams (Akaha) in responsible for this failure; a t harvest some of the this t,rial were quitc low because of poor rainfall. 'rhc fertilizer had not yet dissolved. overall effect of 1euc;iena allcp cropping was t,o Maize yields in the leucaena plots were only about reduce yield hy a n average of 43'%,. This reduction half those in plots without leucaena (Table 57). This was due mainly to the shading eifccts of thc leucacna may have resulted from competition for moisture s takes used to suppor t t h e yam vines. This between the leucaena and maize during the many dry spells in 1982. Maize response to applied fertilizer was highly significant. The interaction between ferti1it.y levels and leucaena treatment was not significant. F e r t i l i z e r Trials Response of y a m s t o fertilizer. Farmcrs usually cult,ivate yams on newly cleared land that has sufficient fertility for a good crop. However, fertilizer application may he needed on land that is cropped for an extended period with a rotation of yams and other X I I I I X I I I I X I I I 1 X crops. This practice reduces the need for clearing X I I I I X I I I I X I I I I X X I I I I X I I I I X I I I I X ncw bush every year. X I I I I X I I I I X I I I I X In fertilizer t r ials conducted this year, the X I l l l X l l l l X l l l l X f'ertilizcr responses of two varieties (Puna and F 4 m - - I Yams/Leucoena -Yams Uendenpruka) of white yams (D.ro tundata) and one variety (Akaba) of water yams (I).a lntn) were highly X . . X . . X . . X variable and in many cases negative. The erratic X I X . . X . . X . . X rainfall of 1982 was probably the cause of these poor X X X . . X . . X . . X results (Table 58). Differences between varieties were X insignificant. Another experiment on nitrogen X . . X . . X . . X sources and yam varieties also produced poor results. X . . X . . X . . X Nor did fertilizer application increase tuher yield X X X . . X . . X . . X significantly on farmers' fields (Tables 59). X X X . . X . . X . . X Response of maize t o K, Mg a n d Zn. Tlle soils in X . . X . . X . . X the Atehubu area arc low in fert,ility, lacking. in X X X X X . . X . . X . . X ;rddition to N and P, some secondary and trace X X elements. Deficiency of these elcments commonly X . . X . . X . . X occurs in maize. Trials for testing thc response of x = Leucoem (pruned 1 = Yoms maize to K , Mg and Zn application included four X = Lewoantl live stoke I I I = Maize or C O Y ~ ~ O S levels each of K 2 0 (0,30,60 and 90 kg/ha) and Mg (0. Fignre 36. Arrangement of food crops and leuraena in an 10.20 and 30 kg/ha) and three levels of Zn (0,5 and 10 alley cropping trial, Atehuhu, Ghana, 1082. kg/ha). A basal application of 60 kg each of N and P205/ha was made on all plots prior to sowing. Tahle 57. Maize yield in a n alley cropping trial with followed by a topdressing of 60 kg N/ha four weeks leucaena. Atehuhu. Ghana. 1982 after planting. Herbicides were used to control Fcrtilixer Yield, kg/ha weeds. The plant spacing was 75 cm x 25 cm. There -rate. kgjha Without With were four replications in each trial. N Pr06 KaO lencaena leuraenaa Mean The results are given in Table 60. At Owowam 0 0 0 1.886 738 1,313 maizc responsed significantly only t(1 K a t rates up to 30 kg K20/ha.T he crop did not respond consislently to Mp and Zn a t this site. At Jat,ozongo grain yield was low hccause ufdry spells a t critical stages of crop growth. Even so, the crop responded consistently to Zn hut not t o K and Mg. Nitrogen u s e efficiency of leucaena leaves a n d "hlnize yield in lei~cnennl ~ l u t sw as r n l c ~ i l a t c dfo r the to ta l area fertilizer. In a trial comparing t,he etFect of dried IXOo i , mama a n d 20'::, lri>cacnalr iot ror a n equiv i l lent :wen leucaena leaves with that of chemical fertilizer on occu~l iedh y rnnixr only. maize yield. Ieucaena leaves were applied a t a rate of Farming Systc>ms 179 Table 58. Response of yams t o fertilizer, Atebubu, Table 59. Response of short season white yam Ghana, 1982 varieties to fertilizer in farmers' fields. Tuher yield, t/ha Atebubu, Ghana, 1982 White White yams Watcr Tuher y~eldt,' hn Nut.ricnt, kg/ha yams (Dcnden- yams -L-abacco Puna N PnOi K20 S (Puna) pruka) (Akaha) Nutrient, kg/ha Main Se~d seed N PzO:, K 2 0 S Zn tubers yams Total yams" 60 30 60 0 (1 8.56 4.73 13.34 6.01 60 30 90 0 0 7.68 3.23 10.91 4.3% 60 30 30 24 0 6.66 X.1:l 14.79 5.19 60 30 30 24 5 9.34 5.2s 14.62 5.10 C.V.. ",' .. . . . . . . . . . . . . . . . 2 2.50 30.40 20.60 39.10 S.E . . . . . . . . . . . . . . . . . . . 1.15 1.4Q 2.06 0.91 "The farnmcr harvested the main tuhcrs of I'una without 3,500 kg/ha, supplemented hy 30 k g Pz05/ha, and inlorming the researchrr. fertilizer was applied a t 90 kg N, 60 kg P205a nd 60 kg KzO/ha. Both leucaena leaves and fertilizer were Table fin. Response of maize t o fertilizer, Atebuhu, applied by three mct,hods, broadcasting, hroadc;rst- Ghana, maior season, 1982 ing and incorporating. and handing, two times (at planting and three weeks afterwards). In one addi- -Yield. kgiha Nutrient, kg/ha tional treatment, a split application of leucaena Owowam. Jatozongn. leaves and fertilizer was banded a t planting and four N P20i K20 Mg Zn Kumayili soil ~Ihmantins oil ~~ - weeks afterward. All 14 treatments were arranged 120 60 0 in a randomized complete block design with four 120 60 0 replic a tl' ons. 120 60 30 120 60 60 The results, shown in Table 61, indicate tha t there 120 60 90 was no significant difference in N use efficiency 120 60 60 bet,ween the leucaena leaves and fertilizer, irrespec- 120 60 60 tive of the time and method of application. Incor- 120 60 60 poration after broadcasting and handing appeared to 120 60 60 give hetter yields than broadcasting, both with 120 60 60 leucaena leaves and fertilizer. Split application of 1,SD (5',Y0). . . . . both gave lower yields than full application. cv.,. " ,.. . . . . . . . Groundnut inoculation. The effect of rhizobial S.E.. . . . . . . . . . . . . . . . . . . . . . . . . 303 41 inoculation on groundnut (Arachis hypogaca L. cv. Konkoma) nodulation and yield was studied a t two fertility levels, no fertilizer and 100 kg/ha each of P Table 61. Effect of leucaena leaves and fertilizer on and K, 20 kg Mg/ha and 10 kg Zn/ha. The N treat- maize yield, Atebuhu, Ghana, minor ments were no nitrogen (control), fertilizer N a t 100 kg/ha and Rhizobium inoculation. All six treat- ments were arranged in a randomized complete block design with four replications. The trials were At planting organized in collaboration with the University of Broadcast . . . . . . . . . . . . . . . . . . . . . . .4 ,146 3,828 Hawaii, which supplied the Rhizobium inoculum. Broadcast and incnrparated . . . . . . . 4.790 3,997 During the major season, the trial was carried out in Handed . . . . . . . . . . . . . . . . . . . . . . . . . 4 ,710 5,584 a field that had heen cultivated for the past 15 years, Three weeks after planting and during the minor season on land just cleared Uroadcast . . . . . . . . . . . . . . . . . . . . . . . 4,546 4,911 from bush fallow. Broadcast and incorporated . . . . . . . 4,229 5,109 Rand~d. . . . . . . . . . . . . . . . . . . . . . . . . 4,596 5,557 In neither trial did the crop respond significantly At planting and four weeks afterward to inoculation in the number of total and active Handed . . . . . . . . . . . . . . . . . . . . . . . . . 3,897 4,025 nodules per plant a t flowering or in seed yield (Table Mean . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 ,416 4,716 6'2). On the new land, the high fertility level had a positive effect on nodulation and yield, but nitrogen C.V .,% . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 S.E. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 426 application significantly depressed nodule for- 180 Farming Systems Table 62. Effect of fertility and inoculation on reported here, which had already begun before the nodulation and yield of groundnuts, disclosure of termination, were hased on obser- Atebubu. Ghana. 1982 vations and discussions of farmer's practices. Major season Minor season Effects of mound size, staking and planting Total No. of Total No. of date. Yam farmers in Atebuhu normally stake their Fertility level and no. of pinkired no. of pinkjred nitrogen treatment nodules nodules nodules norlules yams, except in newly cleared fields where there are only a few trees that can he used as stakes. In this Without fertilizer case farmers leave some of' the yams unstaked. The Control . . . . . . . . . . 5.4 1.8 76.2 39.2 farmers claim that not staking the yams has no effect 100 kg N/ha . . . 9.7 3.5 23.8 5.2 Rhieohium . . . . . . . . 26.7 Ifi.8 79.0 46.7 on yield hecause they plant unstaked yams in larger With fertilizer" mounds to compensate for the expected yield loss. A Control . . . . . . . . . . 2.4 0.4 102.2 63.2 study was conducted to determine the effect ofmound 100 kg Nlha. . . . . . . 7.3 2.8 92.5 17.2 si7,e and staking on the yield of white yams (Dioscorra rotundata, cv. dmtempruka) and water yams (D. alata, cv. akaba). The experimental design was a split plot in four S.E . . . . . . . . . . . . . . . . . 6.7 4.2 13.6 10.6 replications with rnound size, variety and fertilizer in the main plot and staking in the subplot. Mounds =lOO kg/ha each of P a n d K. 20 kg Mglha and 10 kg Znlha. were spaced a t 2 m, 1.4 m and 1 m t o give mation. especially the number of active nodules per approximately 2,500, 5,000 and 10,000 mounds per plant . N fertilizer did not appear to reduce hectare for the large, medium and small mounds, nodulation a t t he cultivated site. The groundnut respectively. The experiment was conducted on an variety used in these trials (Konkoma) can nodulate old yam plot that ~"eceivedfe rtilizer and no fertilizer well in Atebuhu soils without inoculation. treatments. An additional treatment of 30 kglha each Response of cowpeas to Mg and trace ele- of N, Pz06 and K20 was applied to all plots to ments. In this t r ia l the response of cowpeas (VITA-5) determine crop response t o one- and two-year to Mg, B, Mo and Zn application was evaluated. A fertilizer application. The results show that there basal application of 54 kg P205jha was made in all was no ditterence in crop response to one- and two- plots. The total number of nodules per plant a t year application. fo wering was not significantly affected hy any of the Iteducing mound size significantly decreased tuber treatments, although the percentage of active size and tuber yield per mound, hut total yield per nodules was significantly higher in the presence of B hectare increased as the number of mounds increased than when i t was ahsent (Table 6.4). Thc highest yield (Table 64). For each mound size, D. alata was the was obtained when all the elements were applied higher yielding variety, although the percent in- together, but yield did not respond significantly crease in total yield of D. aluta was significantly Lo any particular nutrient. V .Ba lasuhramanian lower than that of D. rotundata in the small mounds and sliehtlv" hi.s.h er in the medium sized mounds. Crop Production Similarly, the percent loss in the average weight of a single tuber was much higher for L). alata in both the During theyear several experiments were planned on medium and small mounds. These observations in- different cropping systems, including rotation dicate that there are varietal dieerences in response experiments, hut when it was disclosed tha t this t,o yam mounds of different sizes. project would be terminated as early as June, all of Staking gave higher yields than not staking, the experiments were discarded. The experiments especially with D. rotundata, the tuber yield of which Table 63. Effect of manganese and trace elements on cowoea vield and nodulation. Atebubu. Ghana. 1982 Nodules per plant Major Pct, of Minor Yield, ky/ha Nutrient, kg/ha season tutal season Major Minor P.05 Mg 13 Mo Zn total active total season se'dson 54 0 0 0 0 11.8 52.0 6.6 1,090 1,250 54 0 2 1 5 19.9 72.1 8.0 1.260 1,542 54 20 2 1 5 18.7 80.1 7.2 1,410 1,516 54 20 0 1 5 13.8 54.7 5.2 1,313 1,412 54 20 2 0 5 17.6 69.4 7.6 1,272 1.2335 54 20 2 1 0 19.1 66.3 6.8 1,180 1,011 54 20 2 I 10 18.8 67.8 9.6 1,177 1,037 LSD (5'::,) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - 13.6 - - CV. . % . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35.8 1r3.8 35.2 13.8 27.5 S.E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . :].I 4.6 1.3 86 177 Farming Sys t ems 181 Table 64. Effect of mound size on vam vield. Atebubu., Gh~a-n~a..~. ..1. 982 ~ - - - ~ Dioscorea rotundafa D.a lala Mound kg p ~ r kg pcr kg pcr k g per size t/ha mound tuber t/hii mound tuber Largc . . . . . . . . . . . . . . . . . . . . 11.78 4.71 1.87 18.50 7.4fi 5.03 (0) (0) (0) (0) (0) (0) Medium . . . . . . . . . . . . . . . . . . 15.79 3.14 1.50 25.15 5.00 3.45 (134.00) (-33.30) (-19.80) (+38.00) (-32.00) (-31.40) Small. . . . . . . . . . . . . . . . . . . . . 24.28 2.43 1.30 30.92 3.09 2.38 (-46.70) (-48.40) (-30.50) (-67.10) (-58.60) (-$2.70) Mcan. . . . . . . . . . . . . . . . . . . . . 17.28 3.43 1.56 24.86 5.18 3.62 (+46.70) (-27.20) (-16.60) (1-34.30) (-30.50) (-28.00) LSD (S'j',) . . . . . . . . . . . . . . . . . 5.06 1.28 0.78 Notc: The numbers in parentheses are percent increases or decreases from the yield of'yams in largr mounds. was significantly reduced by not s t a k ~ n g(T ahle 65). Table 65. Effect of staking on yam tuber yield, With D. alata tuher yield was in general not affected, Atebubu, Ghana, 1982 although when plant,ed in large mounds yield was No depressed slightly wit,hout staking indicating, as Variety Staking staking Mrari shown in Table 66, that there is interaction between kg per mound mound size and staking. Dioscorra rotundata. . . . . . . . 3.78 3.07 3.42 The percent yield loss caused by not staking was (0) (-18.80) (-11.40) also reduced by decreasing mound size. This re- D.alatn. . . . . . . . . . . . . . . . . . . . 5.24 LOX 5.19 duction can he attributed to the reduction in tuher (0) (-1.30) (-0.70) size that occurs when the yam mounds are made Mean . . . . . . . . . . . . . . . . . . . . . 4.54 4.07 smaller. This trend did not hold for the small m---o- u~n~-d~s . (0) (- 10.00) Because their shallow d e ~ t hin hibited further tuber I" ' - (.5'.x' ) development, they gave a higher percent yield loss Staklng means . . . . . . . . . . . 0.24 than the medium size mounds. This suggests that Staking. same variety . . . . . 0.34 Variety means . . . . . . . . . . . 0.24 thcre is a minimum depth in mound size below which C , V , T , . . . . . . . . . . . . . . . . . . . 13.40 the loss in vield caused bv not stakinue can-no-t h.e ~ ~ reduced further hv decreasinp mound size. Note: The numbers in yarentheses are prrccnt yield losses In Atrbuhu yams are commonly grown in large mounds of approximately 2 m x 2 m. Somefarmers, if Table 66. Effect of mound size and staking on yam tuber vield. Atebubu. Ghana. 1982 they arc planting late, use smaller mounds to permit deeper penetration of rain into the mound and t o Yield, kg per mound Percent lower thc soil temperature. This encourages quicker Variety Staking No staking yield loss seedling emergence and compensates for the loss in Large mound growing time. An experiment was conducted in D. rotundato . 5.39 which mound size and variety were main plot n. U ~ U ~. U. . . . . 7.88 7.04 10.7 treatments and planting date was the subplot; the Mean . . . . . . . . 6.63 5.53 17.9 experiment had a split-plot design and was replicated Medium mound D. rutundala . . 3.32 2.95 11.1 three times. Planting began with t,he first rains D. alata . . . 4.91 5.08 -3.4 toward the end of February and continued a t one- Mean . . . . . . . . 4.12 4.02 -3.9 month intervals until the end of April. Spacing Small mound between mounds was 2 m (large), 1.41 (medium) and D. rotundatu . . 2.63 2.23 15.2 1 m (small). Thirty kg/ha each of N, P205a nd K 2 0 D. alata . . . . . . 3.1 1 3.08 1.0 was applied hy ring placement one month after each Mean . . . . . . 2.87 2.65 8.1 planting. All plants were staked, and all plots were Mcan . . . . . . . . . . 4.54 4.07 harvested on the same day. Lsn (5')") for: The results in Table 67 show that the longer the Staking mcans . . . . . . . . . . . . . . . . . . . . . . . 0.24 delay in planting the smaller the tuber yield or, that Staking, same var. and mound size. . . . . . 0.59 as the growing period gets shorter the yield loss Staking, same mound size.. . . . . . . . . . . . . 0.41 hecomes greater. The large mounds suffered the greatest yield loss, which increased from the 5% level can be minimized by reducing mound size. The of significance after one month to the I%, level a t the reduction in mound size reduces tuher size and yield end of two months. Yield loss in the medium size per mound, so that the magnitude in yield loss is also mounds was significant a t the 5'%, level only after two reduced. months, while that of the small mounds was not D. rotundata suffered a significantly greater yield significant even after two months. These results loss than D.a lata when planting was delayed until show that loss in tuber yield caused by late planting April (Table 68). The latter yielded significantly less 182 Farming Systems in March hecause of drought. However. the non- Similarly, the later t he planting date, the shorter the significant yield loss in April seems to indicate that time of emergence. this variety may be less affected hy late planting than Seedling emergence, as affected by mound size and D. rotundata, which is prohahly one of the reasons planting date, was related to soil moisture and that some farmers plant i t even as late as May. temperature. The quicker seedling emergence from Table 69 shows that yam seedling emergence was the small mounds appears to he associated with their affected significantly by mound size as well as by shallow depth, which permits moisture from the soil planting date. The time of emergence was longest for below to be transferred readily by capillary action the large mound and shortest for the small mound. to the developing seedling. With early planting emergence was slower because of high soil tem- Table 67. Effecto f mound size and planting date on perature and dry conditions, whereas with later tuber yield. Atehuhu, Ghana. 1982 planting in April, seedling emergence was quicker I'lantlng date as a result of the cooler soil temperature and more Mound size 26 Fcb 29 March 30 Apnl Mean favorable soil moisture conditions tha t prevail during that month. The quicker seedling emergence kgper mound Large . . . . . . . . . 2.74 1.91 1.66 2.10 may explain why some farmers use smaller than (0) (-30.30) (-39.40) (-2:4.20) normal mounds when planting late. Mcdium . . . . . . . 2.44 1.96 1.65 2.01 Effect of t i l lage and fertilizer on groundnut (0) (-19.70) (-32.40) (-17.40) yield. In groundnut cultivation the method of seed- Small . . . . . . . . . 1.63 1.60 1.06 1.43 bed preparation varies from ridging or plowing to (0) (-1.80) (-34.90) (-12.20) Mean . . . . . . 2.27 1 8 2 1.46 little or no tillage after land clearing, depending on (0) (-17.30) (-35.60) the cropping pattern used by the farmer. To find out IBO (504,) for: if the difi'erent tillage practices have any significant I'lanting date means . . . . . . . . . . . . . . . . . . 0.37 effect on yield, the performance of groundnuts Planti~igd ate, same mound size. . . . . . . . . 0.64i' (Konkoma) was tested in seedbeds prepared by three Mound size means . . . . . . . . . . . . . . . . . . . . 0.35 methods and a t three phosphorus levels (0, 36 and 72 C.V.,'%, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.9 kg P205/haa pplied as single superphosphate). Kotr : The numhrrs in "arenthescs are percent yirld losses. The experimental design was a randomized com~ j11,SI) (l'v,,l 0.87 plete block, with four replications and 60-cm spacing between rows and 15-cm spacing within rows. Potassium was applied to all plots a t 30 kg K20/ha. Table 68. Effecto f p lanting date on yam tuher yield, Atebubu, Ghana, 1982 The experiment was conducted a t one location in the first season and a t another location in the second Planting date season. In the no-tillage plots, except for the initial Variety 26 Feb. 29 March :iO April Mean soil disturbance during land clearing, there was no kgpcr mound further soil disturbance. D. rotundnfa. . . 2.57 2.38 1.36 2.10 No-tillage significantly reduced groundnut yield, (0) (-7.40) (-47.10) (-18.20) and there was no significant difference in yield D.alata . . . . . . . 1.98 1.27 1.56 1.60 rcsponse between plowing and ridging (Table 70). (0) (-35.80) (-21.20) (-19.00) Mean . . . 2. 27 1.82 1.46 Yield was increased significantly by an application of 36 kg P205/hao f single superphosphate. Further LSD (5'7") for: phosphorus application did not have much effect on Varietymeans . . . . . . . . . . . . . . . . . . . . . . . 0.30 yield. The low yields caused by no-tillage can be Planting date means . . . . . . . . . . . . . . . . . . 0.37 Planting date, same variety. . . . . . . . . . . . attrihuted to t,he adverse effects of soil physical 0.52 C V . ' A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.9 conditions on groundnut pod development. With groundnuts some form of tillage appears necessary Not r : The nurnhers i n parei~tlirsrsa re percent y i ~ l dlo sses. for good yields. Table 69. Effecto f mound size and planting date on average t ime of seedling yam emergence, ZAPI-Est Project in Eastern Atebuhu, Ghana, 1982 Cameroon Ranting date As part of Cameroon's Zones $Actions Prioritaires Mound slze 26 F P ~29 March 30 April Mean Integrees de 1'Est (ZAPI-Est) Project, field trials were tzgpcr mound carried out during 1982 a t Uertoua in the savanna Large. . . . . . . . . 12.60 9.40 8.80 10.30 and a t Doume in the forest zone. On-farm trials and Mediunr . . . . . . . 5.90 6.10 4.60 5.50 multilocational trials on yield constraints and crop Small . . . . . . . . . 2.90 2.70 2.40 2.70 fertilization were carried out a t Garoua Boulai in the Mean . . . . . . . . . 7.10 6.10 5.30 savanna, a t Ahong Mhang in the forest zone and a t LSD (5%,). . . . . . 1.06 0.92 C.V.,' x, . . . . . . . various farmers' fields in four ZAP1 Zones, Diang- 25.10 Belabo, Nguelmendouka, Angossas and Doume. The Table 70. Effect of tillage method and phosphorus application on groundnut yield, Atehuhu, Ghana, 1982 14'irst season yield. ky/ha Second season yield. kg;hn Phosphorus rate No tillage Plow Ilidgc Mean No tillagc Plow Ridge Mean 0 kg P,,O,/ha - A ,, Pod . . . . . . . . . . . . . . . 1,188 1.463 1,451 1 Kernel . . . . . . . . . . . . 847 1,021 991 36 kg P,O,/ha Pod . . . . . . . . . . . . . . . 1,607 1,766 1.862 1 Kernel . . . . . . . . . . . . 1,195 1,257 1,313 1.255 72 kg P,O,/hi\ Lo'd . . . . . . . . . . . . . . . 1,545 1,940 1,715 1,733 Kernel . . . . . . . . . . . . 1.051 1,388 1,224 1,221 Mean Pod . . . . . . . . . . . . . . . 1,477 1,723 1,676 Kernel . . . . . . . . . . . . 1.0'31 1,222 1,176 LSD (5%,) for: Pod, till. and F means . . . . . . . . . . . . . . . . . . 177 Kernel, till. and P means . . . . . . . . . . . . . . . 129 C.V.., ',X~ , Pod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.0 18.0 Kernel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.4 17.8 crops used in the trials were maize, groundnuts, ears attacked by insects and diseases (Tahle 74). At sweet potatoes, cassava, rice, cowpeas and pigeon thc rescarch site, however., the use of improved peas. Only part of the data from thc first season trials varieties and appropriate agronomic practices. such were availahle fcrr this report. as weeding, plant density and fertilizer ;rpplicat,ion. increased maize yields significantly. Yields of Maize improved varieties were about twicc those of local O n - f a r m a n d mul t i loca t ional t r ia l s . These varieties. On tlre avcrage 48%, of the overall yield trials were carried out in cooperatio~lw ith Young increase can be atkibuted to fertilizers, 34'j.;, to plant Farmers of ZAPl-Est, t h e Farmer Cooperat,ive density and 18% to weeding. Fokpayono a t Garona Roulai, and the Agricultural Soil fer t i l i ty managemen t . Three field trials Technic School a t Abong Mbang. Three improved wcre conducted simultaneously a t Abong Mhang, maize varieties, EMC, TZSR-W and TZR, wcre Ucrtoua, and Garoua Boulai t o study the effect of compared with local varieties at three levels of' fertilizer application on maize (EMC) planted under management and fert.ilization in 15 farmers' fields in different environmental conditions in eastern four zones. The crops were planted and managed by Cameroon. On plateau soils a t Abong Mbang, maize the farmers with assistance from LRA-Est (Tnstitut de responded significantly to the application of 60 kg la Recherche Agronomique) researchers and ZAI'T- N/ha and 60 kg IJzO5/ha.O n soils in the upper part of Est technical officers. At harvesttime, 8 out of 15 a valley side slope a t Garoua Roulai and on soils in trials yielded good data for comparison. the lower portion of a valley side slope a t Rertoua. The same three maize varieties used in the nn-farm maize responded to all nutrients, although only the trials were also tested against local varieties a t three response t1) nitrngen was significant (Tahle 75). research locations, Bert,oua, Garoua Roulai and Ahong Mbang. In these trials the variety EMC was P lan t ing da t e . Three maize varieties, EMC. TZR also tested under eight different combinations of and TZSR-W, were planted on three dates, 30 March. planting, weeding and fertilizer application. The 29 April and 1 June, in a split-plot design. Late trials were carried out by IRA-Est research staff. The yields of the local variety, EMC, TZU and Table 71. Yield of maize varieties planted by farmers, TZSR~Wu nder farmers' management (Table 71) were Cameroon. first season. 1982 considerably lower than a t the research sites, where Yicld. kg/ha optimum agronomic practices tripled the yields of Trial Local EMC TZB TZSR-W the improved varieties (Tahle 72). KANDA I . . . . . . . . . 937 631 833 659 On the farms, although improved varieties and NKA 1 . . . . . . . . . . . . 981 928 779 817 fertilizers failed to increase yields, the use of a higher K.4NI)A I1 . . . . . . . . 1,430 1,729 1,652 2,312 plant stand boosted production hy about 32% (Tahle NKA I1 . . . . . . . . . . . 760 577 739 557 73). Observations on crop characteristics of maize ANG.1. . . . . . . . . . . . 544 469 512 490 a t harvest showed that the traditional method of ANG. I T . . . . . . . . . . . 1,696 1.958 2,000 1,854 seeding resulted in a lower plant populat,ion at AN(;. I11 . . . . . . . . . . 1.093 1.104 895 1.145 harvest, a lower percentage of harvested ears and a ANG. IV . . . . . . . . . . 1 1097 807 1.287 1.343 higher percentage of big ears, unproductive ears and Means.. . . . . . . . . . . 1.067 1,02R 1.087 1.147 184 Farming Systems planting significantly decreased yields regardless of when i t was seeded on 3 April to about 1,186 kg/ha the varieties used (Table 76). Streak infestation in when it was seeded on 2 June. The effects of fertilizer the susceptible varieties (EMC and TZB) was quite applications on groundnut yields were not clear, as high in the 29 April planting hut did not reduce was the case in 1981. This may be due t o the high rate yields. The 1 June planting was ohviously too late ofRosette virus infestation (30% average incidence). and resulted in stunted plant growth. Weed cont ro l . Groundnut variety 68-18 was Sc reen ing of herbicides. One of the major subjected to seven weeding treatments. Dry fruit problems of maize production in eastern Cameroon is yield of groundnuts increased significantly fi.om the shortage of labor for weeding during the early 1,116 kg/ha in the unweeded plot to about 1,950 kg/ha vegetative growth of the crops. A trialwasconducted or more in plots where various weed control practices to screen locally availahle herbicides. Maize yields were used. Stomp applied preemergence a t 1.2 kg greatly increased when weeds were controlled. Of the a.i./ha gave good weed control and a n excellent yield. herbicide treatments, Atrazine at 2.0 kg a.i./ha plus A good single weeding hy hand is apparently just as Stomp a t 1.5 kg a.i./ha applied preemergcnce gavc the eEcctive, though. highest yield (4,362 kg/ha), although i t did not differ significantly from yields with the other herbicide Cont ro l of leaf diseases. In addition to Rosette treatments or with two weedings by hand (Table 77). virus. groundnuts planted in eastern Cameroon are heavily attacked by a leaf disease caused by Groundnuts Cercosporiosis. The fungicide Peltas was applied a t a rate of 3 kg of commercial product per hectare on five On-farm trials. On-farm, demonstration trials on groundnut varieties, 65-7, Bertoua Blanche, 68-16, groundnuts were carried out a t six locations in the Ongnegne and Nkometou 11, to control the cerco- first season of 1982. Groundnut variety 68-16 gave a n sprrriose. Depending upon the variety, Peltas appli- average yield of about 1.233 kg/ha. 27.3 percent more cation yield from 27 to 68'%,( Table 79). than the yield of local varieties (Tahle 78). Sweet Potatoes S e e d i n g d a t e a n d f e r t i l i z e r a p p l i c a t i o n . Groundnut variety 68-16 was planted on three dat,es, Four promising sweet potato clones selected from 3 April, 6 May and 2 June, and treated with six last year's trials (TIR 1, TIB 2, TIS 23303 and TIS combinations of N. P and K fertilizer. Fruit yields of 527034) were tested a t three locations from May to groundnuts decreased significantly from 1,862 kg/ha Table 73. Yield of maize varieties planted by farmers Table 72. Yield of maize under different cultural under different cultural practices, practices, Cameroon, first season, 1982 Cameroon, first season, 1982 Yield, kg/ha Abong Garoua Variety and treatment Mhang Boulai Bertoua 1,ocal (traditional") Local . . . . 968 1,356 964 40.1 -0.4 No fert.,n o weeding. 386 a 1.152 a 196 a EMC . . . . . . . . 962 1,215 908 26.3 -5.6 I.ocal (researchb) TZB.. . . . . . . . 1,136 1,327 625 16.8 -45.0 Fcrt., weeding" . . . . .2,2fil ef 2.892 ahcd 478 ah TZSR~W. . . . . 972 1,455 1,062 49.7 9.3 EMC (traditional) Mean . . . . 1 .009 1.338 890 33.2 -10.4 No fert., no weeding. 569 ah 1,446 ah 1,139 br: "Maiec wits seeded according to l.he t radi t~onalm etl~oda nd Fcrt., no weeding . . .1,426 abc 2,892 a h c d 2,083 dcf wirhout fertilizer. No fert.. weeding . . . 790 hcd 2,083 abc 1,629 c d "Maizr was weeded at 50.000 plants/hn a t 80 cm x 50 cm spacing Pert., weeding. . . . . 1 . 9 3 0 d e 3,647 cdcf 2,389 ef'g and withoul. fertilizer. EMC (rcsearch) "hlaize wiis seeded nccurding to the traditional method wi1.h No fert., no weeding. 1,275 cd 2,:140 abcd 1,629cd fe~.tilirera t 80 kg N plus 40 kp P205plus4 0 kg K,O/hn. Fert.,n o weeding . . .2,445 e 4,485 def 2,426 fg No fert., weeding . . 2,316 e 3,223 bcde 1,691 cde Fert., weeding. . . . . .2,650 ef 5,171 ef 2.671 fg Table 74. Crop characteristics of maize planted by TZR (research) farmers, Cameroon, first season, 1982. Frrt., weeding. . . . . .3,126 f 5,551 f 2,855 g Method of seeding TZSR-W (research) Characteristics Traditional Research Fcrt.. weeding. . . . . .2,46:3 ef 5.312 ef 3,075 g Plant population at harvest, Note: Any two means in t h r samc rulumn followed by t h r same plantslha . . . . . . . . . . . . . . . . . . . . . 20,460 28,050 letter are not significantly different at t h e 5'x levrl uf Percentage of harvested ears (total prubahiiity. harvested over plant pop.). . . . . . 86 93 "Maize was sreded according to t h r traditional method. Percentage of big ears . . . . . . . . . . . 32 29 "Maize was seeded at 50.000piants/ha with spacing of 80 cm x I'ercentage of ears attacked by 50 cm. insects and diseases . . . . . . . . . . . 23 'I.'ertili~rr was applied a t 80 kg N, 40 kg P20, and 40 kg K20/ha. 21 "One hand weeding was done fuur weeks after seeding. Percentage of unproductive ears . . 13 11 Farming Systems 185 Table 75. Yield of maize a t three locations under Table 77. Yield of maize with different weed control different fertilizer treatments, Cameroon, practices, Bertoua, Cameroon, first season, first season. I982 1982 Fertilizer Yield, kg/ha rate, kg/ha Abung Garoua Weed control treatment N PzOi K 2 0 Mbang Bertoua Boulai No weeding.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.053 a 3,753 a 2,570 a One hand weeding Sour weeks after germination 3,750 bc 5,26:3 hc~i Two hand weedings four and seven 2,738 ah 4,600 h weeks after germination. . . . . . . . . . . . . . . . . . . 3.035 b 4.980 hc Atrazine, 1.5 kg a.i./ha (preernergencc) . . . . . . . . 60 60 60 3,779 c 5$59 cd 41921 hc Atrazinc, 2.5 kg a.i./ha (prcemergence) . . . . . . . . 120 60 60 4,181 c 6,069 d 5,434 c Atrazine, 2.0 kg a.i./ha, and Stomp, 60 120 60 4.196 c 5,590 cd 4,849 bc 1.5 kg a.i./ha (preemergencc) . . . . . . . . . . . . . . . 60 60 120 3.750 bc 5.446 bcd 4.887 bc Simazine, 2.5 kg a.i./ha (preemcrgmcc) . . . . . . . . Atrazine, 1.5k g a.i./ha( preemergence) + 2,4-D. Note: Means in t hc samc column followed by thc samr letter are 0.5 kg a.i./ha, four weeks after germination . . not significnntly diffrrent a t the 6% lrvrl of probability. Atrazine, 1.5 kg a.i./hap reemergence) + one hand weeding seven weeks after grrmination. 4,088 bc Table 76. Performance of maize sown a t different Note: Means followed by t h e samr lettcr tire not significantly dates, Bertoua, Cameroon, first season, different at the5"A, lrvelof probability. 1982 Y~eld, Plant Table 78. Yield of groundnut varieties planted by Plant~ngd ate kg/ha Streak, 'Yo hhe~ghtc, m farmers, Cameroon, first season, 1982 I? MC7 A16 Local 30 March . . . . . . . . . . 5,097 h 7.8 c 270 a Tradi Re- Tradi- Re- 29 April . . . . . . . . . . . 3,875 c 23.3 a 260 i~ Trial 1 June. . . . . . . . . . . . tional search" Mean tional 2,467 d search Mean 7.1 c 205 b TZU UIANG . . . 1,980 1,087 - 870 744 30 March . . . . . . . . . . 6,013 a 8.6 r 255 a NKA I . . . . 521 770 - 289 9'15 - 29 April . . . . . . . . . . . 3,947 c 16.3 b 263 a NKA 1 1 . .. 860 904 - 512 588 - 1 June. . . . . . . . . . . . 739 d 5.2 c 201 h ANG.1 . . . . 1,120 1,000 - 1,240 1,640 - TZSR-W ANG. 11 . . 816 252 424 472 - 30 March . . . . . . . . . . 4,805 b 3.0 c 263 a DOUME 1 . 2,800 1,740 - 780 2,100 - 29 April . . . . . . . . . . . 3,989 c 4.9 c 267 a DOUME I1 1,800 1,600 1,400 1,600 1 June. . . . . . . . . . . . 3,078 4.0 c 213 h Mcan . . . . . 1.414 1.060 1.231 787 1.152 969 Note: Means in t hc same column followed by the same lettcr arc Note: Plant pupulation was 200.000 plnntslha with spacing of rrot significantly different a t the 50/, level of prubahility. 40 cm x 26 cm. Table 79. Yield of groundnut varieties treated against leaf spot disease, Bertoua, Cameroon. second season. 1982 Octoher 1982. The highest yielder, as last year, was Yield, kg/ha Percentage TIB 1,w hich gave average marketable tuber yields of Variety Control Treated* inrrease about 17.8 t /ha (Table 80). 65-7 . . . . . . . . . . . . . . . 1.579 2.,0 05 2- .7 ~~ Rertoua Blanche . . . . 995 1,685 68 Intercropping 68-16, . . . . . . . . . . . . . . 1.458 1,995 37 Ongnegne . . . . . . . . . . 1,806 2,380 32 A trial was carried out to confirm previous findings Nkometou 11. . . . . . . . 1,361 1,875 38 on crop arrangements for maizejgroundnut inter- "Groundnuts wcrg trcated wiih 3 kg of Peltns per hectare. cropping. The results of the trial confirmed last beginning when spots were first ohserved and continuing until year's finding that maize in double rows gave the harvest a t 15-day intervals. highest land productivity value. The land equivalcnt ratio of this system was 1.28 (Table 81). Yields of maize planted in association with groundnuts in two Table 80. Yield of sweet ootato clones a t differe~nt- -. locations in Eastern Cameroon, 1982 syst,emsd id not decrease appreciably, yields of maize planted according t o a third system, the farmers', Marketable yield. t/ha were significantly lower. The dry fruit yield of Variptv ~~~t~~~~ nnllmAr nrnzmRo M~~~ groundnuts was reduced significantly in association -- with maize, regardless of the crop arrangement used. TSB 2. . . . . . . . . . . 18.5 13.4 6.5 12 Trials on maizr/cassava intercropping were also T1S 23303. . . . . . . 10.8 18.1 11.4 13 carried out , but not all the results were available for TSS 527034. . . . . . 16.7 11.0 12.2 13 Local . . . . . . . . . . 10.9 - - this report. 186 Farming Systems Table 81. Performance of intercropped maize and groundnuts, Bertoua, cameroo", 1982 Maize Groundnut Land yield, yield, equivalent Treatment kg/ha kg/ha ratio Maize alone. . . . . . . . . . 5,156 a - 1.00 Groundnuts alone . . . . -~ 1,749 a 1 .OO Maicelgroundnuts SystemA . . . . . . . . . . 4,791 a 552 c 1.24 System R . . . . . . . . . . 4,352 a 760 bc 1.28 System C . . . . . . . . . . 2.541 b 987 hc 1 .O6 Note: Two means followed by tirt. same lrtlrr are not significantly differ~nla,t the 5':: level of proh~bil i ty. Farming Systems Research Network in East Africa For the past six years, CIMMYT has operated an economics program in eastern Africa. A senior economist gathered and analyzed baseline data on the physical, biological, socioeconomic and sociocul- tural environments of groups of Farmers in selected areas. Survey methods for gathering such in for^ mation are being developed and communi(:ated through training prugrams to some national in- stitutions in Fast Africa. An agronomist from IITA's Farming Syst,ems Program has now been posted with CTMMYT's program in East Africa. In addition t,o helping develop farming systems research methods. he will conduct research on technology developed a t ITTA. This technology is intended to aid soil conservation (through reduced tillage systems. mulching, allcy cropping, and mixed and relay intercropping); reduce inputs and increase yields (by means of mixed and relay intercropping, mulching systems, rhizohial nitrogen fixation and rnycorrhizal phosphate nutri- tion); reduce drudgery (through weed control and low cost tools such as the rolling injection planter); and employ genet,ically improved varieties of various crops (grain legumes, cereals. and root and tuber crops). Technology from other sources (for example, high-to-mid-altitudem aize and rice, drought tolerant pulses, and pigeon peas) could also be adapted to the region. 8'1111 participation in the East Africa project hy llTA has been hindered by unforeseen administrative delays. Preliminary cuntacts suggest that there is a great need in the essentially maize-based farming systems of eastern Africa for IITA technt~logyin rice, cassava and the pulses. In this region, as in West Africa, crop production is usually increased hy bringing more land under cultivation (t,hough the increase in productivity lags behind pc~pual t 'i on growth). 1,ow-cost technology, such as improved varieties with resistance t,o stresses, mixed and relay intercropping and biological processes, would enable farmers to intensify production per unit area. Fertilizer and other soil ammendments, though costly, will have to he used.-H.C. Ezumah Training Program awarded to 180 students, representing 10 countries and 12 universities of Africa. The lnstitute remains in IITA was established to serve as a center for touch with these former scholars, many of whom now agricultural research and training. Through its have positions in research institutions, universities training program, the Institute helps prepare agri- and international organizations, including IITA. cultural scientists to solve food production problems in the world's humid and suhhumid tropics. The Institute also trains research workers to assist Non-Degree-Related Training agricultural scientists and extension supervisors to Training of research workers and extension per- transfer new technology to agricultural producers. sonnel is carried out in the non-degree-related A total of 655 people received training through training program and group courses. Through the IITA in 1982, including, fur the first time, parti- former the lnstitute responds to requests for training cipants from Belize, Cuba, Haiti, Mozambique, in agricultural technology for employees of depart- Switzerland and Vietnam. The numbers and count- ments and ministries of agriculture, universities, ries of people that have received training through agricultural experiment stations, international IITA since it opened in 1970 are listed in Table 1. The organizations, and private agencies in the humid and types of training programs offered by the Institute subhumid tropics. Training is organized on an arc described in the following sections. individual basis to meet the specific needs of each research training associate. Because their individual Degree-Related Training needs vary widely, sodoes the length of the programs. from two weeks to nine months. In the degree-related training program, postgraduate In 1982 the Institute received into this program 26 students from universities throughout the world persons, representing 12 nations. The participants conduct the field work portion of their degrees a t acquired research and technical skills, working IITA under the supervision of scientists. The under the supervision of IITA scientists and program is designed primarily to give students from t,echnicians (Table 3). the humid and subhumid tropics the opportunity to conduct their field work in the tropics with the crops, soils and farming systems to which they will return Group Courses upon completion of their degree programs. Group courses on various areas of' agricultural During 1982,:14 Master's degree students (research production in the humid and subhumid tropics are scholars) from 10 countries and 30 doctoral students organized as the need for training larger numbers of (research fellows) from 12 countries were engaged in research workers and extension supervisors in a research under the supervision of IITA scientists. In part~culara rea becomes apparent. The demand is all, 17 countries were represented, of which 12 are in currently so great that the number of appl~cations Africa, and 21 universities, of which 7 are in Africa. received for courses typically exceeds by two or three Ry the end of 1982, a total of 143 research scholars times the number of places available. and 87 research fellows had conducted the field work The group courses program expanded significantly portion of their degrees at IITA. The students' names in 1982, offering 21 courses, two of which were and the topics of their studies are listed in Tahle 2. conducted in Cameroon and one in Upper Volta. The total number of participants was 554, more than Vacation Student Research double the number received in the previous year, Scholarships durlng which 11 courses were offered, with 253 participants. The vacation student scholarship program was cre- One of the highlights of the group courses program ated to inrtiate and maintain cooperative relation- in 1982 was the develowment of traininp manuals for ships with agriculture faculties in Africa, some of maize, cowpeas and soybeans, root and tuber crops, which have no postgraduate programs, and to and soil and plant analysis. The maize and root and identify promising young students and motivate tuber crops manuals have been translated into them to pursue careers as agricultural scientists. French, and eventually all of them will be produced Scholarships are awarded to students in the next to in both French and English. Another highlight was a last year of their tirst degree programs. During their 64-hour, intensive course in agricultural research last long vacation as undergraduates, the students management, which was conducted a t IITA by the carry out field and laboratory studies under the International Service for National Agricultural supervision of IITA scientists. Research (ISNAR). Fifty-eight IITA scientists and The program has attracted nominations from research scholars and fellows completed the course, faculties in French- and English-speaking Africa. which consisted of a tightly integrated program of From 1971 through 1982, vacation scholarships were lectures, case studies, exercises, games and projects 190 Training designed to improve the managerial skills of the multiplication and production. Nine persons partici- participants. The course was received with much pated. enthusiasm by the present and future agricultural Soil and water conservation research (15 scientists who took part. The 21 group courses offered a t IITA and off site March to 2 April). The principal objective of this this year are described in more detail in the following training course/workshop was to acquaint re- paragraphs. Information about courses conducted off searchers from agricultural research stations of the site from 1974 to 1982 in cooperation with national humid and subhumid tropics of Africa, Asia and agencies is listed in Table 4. Latin America with the current state of knowledge about erosion problems. principles of erosion con- Communication planning and strategy in trol and techniques for conducting experiments Africa (10 to 22 January). This course/workshop in erosion. There were 24 participants from 16 was conducted jointly by Cornell University (United countries. States) and IITA. It sought to respond to the need of ministries and other agencies to communicate more Seed yam production (2" to 26 March). This effectively with the potential beneficiaries of rural course was requested and sponsored by the Ayangba development programs, with other groups that are Agricultural Development Project, Nigeria. Its vital to the success of those programs, and with the objective was to provide practical training in seed general public. There were seven participants from yam production to field technicians who are responsible for accelerating yam production in the three countries. project. Nine persons participated. Soil and plant analysis (18 January to 26 February). Field surveying and data collection (29 March This course was conducted jointly by the Centre for lnternational Programs of the University to 8 April and 23 August to 4 September). Two of Guelph, Canada, and IITA. It was funded primarily courses were conducted in Rambui, Cameroon, in co- by a grant from the Canadian International De- operation with the Cameroon institute of Agronomic velopment Agency (CIDA). The principal objective of Research. The primary objectives of the courses were the course was to train senior laboratory technicians to familiarize extension field demonstrators with field surveying, data collection, and interpretation and technologists in the management, methodology, instrumentation and techniques of soil and plant techniques and to instruct them on group farm analysis, with special emphasis on soils and crops of organization. The courses were designed to prepare tropical regions. There were 21 participants from 16 field demonstrat,ors to assist scientists of the Cameroon NationalResearch and Extension Project, countries. who are working with IITA scientists to build up Maize production (8 February to 30 April). The Cameroon's on-farm research capability and improve objective of this course was to train research workers technology transfer to its smallfarmers. Seventy-tive and extension supervisors in improved methods of people participated. maize cultivation and experimentation and to acquaint them with maize research and production Intensive maize production (21 to 25 April). This course was planned, organized and conducted technology. The course focused on the different for extension personnel of three Nigerian state environments of maize production in tropical Africa, ministries of agriculture and natural resources by on identification of various field problems, and on participants in the 12-week maize production train- practical solutions to problems common in Africa. Thc course was designed to teach participants how to ing course offered by IITA in 1982 (see the description above). For the participants in the maize course, this perform simple applied research trials a t experiment course served as an exercise in planning and con- stations and on farmers' fields and t,o demonstrate ducting t,raining. Their primary objective in offering new cultural practices. There were SO participants from 16 countries. the course was Lo bring state extension personnel up to date on maize research, production and extension. Weed control (1 to 12 March and 7 to 18 June). Thirty-two people participated. Two courses in weed control were conducted in 1982 for IITA field technicians and representatives of the Maize and rowpea production (15 March to Nigerian Federal Department of Agriculture. The 9 April). This course was conducted in Upper Volta courses covered use and application of herbicides. by the IITAiSAFGKAD team a t the request and including sprayer calibration. There were 63 par, under the sponsorship of the government of Upper ticipants. Volta and the U.S. Agency for lnternational Development (USAID) foundation sced production Root crops multiplication (1 to 10 March). Thin project. It was designed for field extension personnel course was conducted a t the request of the Nigerian responsible for accelerating maize and cowpea National Seed Service and was sponsored by that, production in Upper Volta. These people were joined organization. The primary objective of the course by f ve of their colleagues from the Benin Ministry of was to train National Seed Service personnel in Agriculture who have similar responsibilities. The improved methods of tropical root and tuber crop latter were sponsored hy the Food and Agriculture Training 191 Organization (FAO) of the United Nations. The research workers and extension supervisors in rice primary objectives of' the course were to train field production methods and varietal evaluation under extension personnel and research workers in im- irrigated, hydromorphic and upland conditions. proved methods of maize and cowpea cultivat,ion and There were 23 participants representing 13 countries. experimentation and to acquaint thcm with applied research and production technology for the two Tissue cul ture of tropical roo t s and tubers (25 crops. There were 20 participants from two countries. October t o 12 November). The objective of this course was to familiarize research workers with Tropical root a n d tuber crop production (10 simple tissue culture techniques and in particular to May t o 9 July). The primary objective of the course train them in safe handling and testing of tissue was to train research workcrs and extension super- culture material upon its arrival in the recipient visors in improved methods of tropical root and tuher country. The course was sponsored by the UNDP crop production and acquaint tlwm with applied grant, Technology Transfer on Root and Tuber research and technology. The course focused on the Crops. There were 10 participants from 8 countries. differente nvironment.s in which root and tuber crops are grown in the tropics, on idcntificat,ion of prob- Management tools a n d perspectives for agri- lems, and on practical solutions to those prohlems. cul tura l research (8 t o 20 November). This 64- The participants worked alone and in teams in the hour course for IITA research scholars and fellows field, greenhouse, 1abor;rtory and classroom. They and scientific staff was conducted largely in the were able to perform and demonstrate procedures for evenings and on Saturdays. It was offered by ISNAK releasing new clones of these crops, plan and conduct as a joint undertaking with IITA. The principal applied research projects, interpret dat.a. and write ohjet:tives of the course were: (1) to introduce reports. The course was fiindod primarily by the scientists and future scientists to management United Nations Development Programmr (UNUP) tools sl~clia s budgeting, scheduling and manpower under its joint grant, entitled Technology Transfer pl:inning, (2) tu improve the decisi(111-making cap- on Root and Tuber Crops, to C'ent.ro Tnternacionnl ability and communication skills of the participants. de Agricultura Tropical (CIAT), the International and (3) to improve thcir ability to plan, implement Potato Center (CIP) and IITA. There were 33 and rvnlnate research programs. Theye were 58 participants from 25 countries. participants from 20 countries. Cowpea production (20 t o 22 June). This course Genetic resources conservation (15 November was requested and sponsored hy the Kana State t o 3 December). This course was conducted jointly Agricultural Development Authority, Nigeria. The by IITA and the International Board for Plant primary objective of the course was to train Genetic Resources (IBPGR) and was funded by a extension supervisors and other extension personnel grant from the latter. The overall objective of the in improved methods of cowpea production that course was to train participants in the collection and are now becoming available. Thirty-six people conservation of crop genetic resources. The course participated. covered all major practical aspects of germplasm collection and conservation, including field tech- Intensive course i n tropical root a n d tuber niques and gene bank activities. There were 19 crop production (5 t o 9 July). The participants in participants representing 15 countries. IITA's 10-week course in tropical roots and tubers (discussed ahove) planned, organized and conducted Cowpea a n d soybean production (22 November this week-long course for extension personnel of t o 17 December). The primary objective of this Nigeria's Ogun-Oshun Basin Development Authority. course was to provide research workers with the Their primary objective was to bring the participants practical knowledge and skill they need to establish up to date on tropical root cropsresearch, production and manage field trials and to take advantage of and extension. Sixteen persons participated. improved lines of cowpeas and soybeans distri- huted through international cooperative trials and Orientat ion to tropical food crops a n d farming nurseries. There were 33 participants from 22 systems research (20 t o 30 September). This countries. course was requested and sponsored by the National University of Benin for agriculturalstudents in their final year of academic training. The main objective of the course was to acquaint the students with research conducted a t IITA and in the humid tropics on food crops and farming systems and to assist them in identifying projects for the research portion of their degrees. There were 36 participants from two countries. Rice production (11 October t o 19 November). The principal objective of this course was to train 192 Training Table 1. Numbers a n d countr ies of par t ic ipants i n IITA's t r a in ing p rogram f rom October 1970 t h r o u g h December 1982 Vacation student Research Research Research research training Countries Total scholars" fellowsh scholars associates Courses Africa Angola . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1 6 Benin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 25 12 7 93 Botswana . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1 4 Burundi . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6 Cameroon . . . . . . . . . . . . . . . . . . . . . . . . . . 88 9 17 57 Central African Republic . . . . . . . . . . . . . 13 1 12 Chad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1 5 Congo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 3 19 Egypt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 I 4 Ethiopia . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 1 2 17 Gabon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4 Gambia . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 18 Ghana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 7 4 16 17 75 Guinea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 5 24 Guinea-Bissau . . . . . . . . . . . . . . . . . . . . . . 9 9 Ivorycoast . . . . . . . . . . . . . . . . . . . . . . . . . 18 3 15 Kenya . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 2 3 40 Liberia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 3 12 :3:3 Libya . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 Malagasy Republic . . . . . . . . . . . . . . . . . . 4 4 Malawi . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 1 17 Mali . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 9 39 Mauritania . . . . . . . . . . . . . . . . . . . . . . . . . 9 9 Mauritius . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1 1 2 Mozambique . . . . . . . . . . . . . . . . . . . . . . . . 1 1 Niger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1 12 Nigeria . . . . . . . . . . . . . . . . . . . . . . . . . . . . 780 15 32 116 42 575 Rwanda . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1 1 1 8 SBo Tomb . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5 2 Senegal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 2 29 Sierra Leone . . . . . . . . . . . . . . . . . . . . . . . . 84 2 13 22 47 Somalia . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1 8 Sudan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 I 15 Swaziland . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Tanzania . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 2 2 24 81 Togo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 2 1 5 1 :i5 Uganda . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 3 1 4 4 26 Upper Voltd . . . . . . . . . . . . . . . . . . . . . . . . 46 1 1 1 2 41 Zaire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 16 10 15 67 Zambia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2 18 Zimbabwe . . . . . . . . . . . . . . . . . . . . . . . . . . 13 9 4 Total for 41 countries . . . . . . . . . . . . . . . . 2, 015 85 64 180 203 1 .4 83 Asia Bangladesh . . . . . . . . . . . . . . . . . . . . . . . . . 3 1 2 Japan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1 1 India . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2 2 2 10 Indonesia . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1 10 Malaysia . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6 Pakistan . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1 1 Philippines . . . . . . . . . . . . . . . . . . . . . . . . . 12 2 I 9 South Korea . . . . . . . . . . . . . . . . . . . . . . . . 2 1 1 Sri Lanka . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1 2 11 Thailand . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1 2 Vietnam . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Total for 11 countries . . . . . . . . . . . . . . . . 73 5 2 1 10 55 Australasia Australia . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 I 2 Papua New Guinea . . . . . . . . . . . . . . . . . . 6 1 4 Total for 2 countries . . . . . . . . . . . . . . . . . 8 1 2 1 1 'sEod'\\ot ur sJJnpoJo.rdu ouJaJas Erro8rN'upppql uorlEreua8 trJreaJ o uosrredtu.rC oqd qbqls S t{ Jo,{ lrsra^rul l EpuESO d.n?lN lI g i (rD"rro s) lrAdaA{s crJ aq} ol suol}rpu()J luardj lrp rapun parols uaFEquap BrrrnrN uepeql au()i).I sartdtJrl^r JIJ.Jo. {J r lrql ldarsns o{d 'pn{ .il I Jo dlrsra^rull Er.rors sllog'oql{v 'EAeSSUJ o t Jo pl.rd snotaqnl uo ] laJi} Jraql puB sraltEJnqJ Jr( louorSE euag rN 'uEpEq I ')ue]lodrurS uouE uol lElJossV oqd uqEH 'y 'sPJd,\\oJ s ar rvz n8unqe ll NJ I 'Z u Jo,{ l lsralrul l o rrorlEJrlddE aprrr l .asur orunlo^ qBrq Eua8 (N 'uep€q l puu ,^o l Prl ln Jo uol lnnlE^fl oqd qSurs U S Jo I lrsro^ruo o8o.L eruV.EI trtr1 snaolloJq creasau rPfu ilarnoc VJII u86I nurJnp VJII le aJuoprsal ur srploqcs pue sraolla.Iq creasau .z olqr'l i^at rPrpuEr ' ]u. l r?^rnho Itlroiro0rl ro r r . r : j3p s,ra lsr t r { roJ sJtEprpupJ, I t 9 t 9tz t8L l8 t t I 892 7, I ' ' ' ' ' ' ' s a l , r l u n oID r o J l B ] o J I t '' l]OrutsqU JOlSal\ T I . . . . . . . . . . . I?.FuoJ I t s p u E l sul o u r o l o s 7, z . . . . . . . . . . . . . . !!r.'r uorSoll JgrJEd 9ti It ' sarr lunor i l toJ ' ' ' ' ' ' ' E I O n ZIPOtoUJ7 Z a A t v . . . . . p B p r u t l J I t - nrad ' ' ' ' ' ' ' I ] n B e t E J r N I ' ' ' ' ' ' ' ' ' €oIEIUET I . I u ' ' ' ' ' ' ' l t l uH € u B . { n f ) ' ' ' ' ' ' ' : ) t l q n d o u u r l i r u r u r o ( I ' ' ' ' ' ' - I ] r r u r l l l o ( l t - EqnJ I - eJru EtsoJ I z ' ' ' ' ' ' ' E r q t u o l o c v l t I I . . . . . . . . . . I r z e J [ J I I ' ' ' ' ' ' " " a z r i o g I'rrraruv Ierluac pue q]nos 0ti 8 l 9 8q ' ' ' ' ' ' ' ' s a l J l u n o ) zJ o ll 6A g I I- t 0q ' ' ' ' s o l r ? l s p a ler?Lor lll I t, ' ' ' - - L e p P u r ? J ecualllv qFoN ftI LI OL - - - - - s r r r l uno ) q roJ I -- l e l oJ I putsuozlr^\nd I I ! OI . . . . . . s P u e l J a q l a N z 6 L7 ' . . . , t u E t u r r 3 l s a j l L t 9 0 t . . . . . . . . . p u r l ; u g t 7 ZL . . . . . . . . . u l n r t s l a g adoJng sosJno ) sreloqJs q:-,^o lloJ PsrelorlJs Ir?loJ sorJlunoc SUrUrI?r l qrrre:_aH r{J.rEasa}l qJrvai-dtT ' luapnls panurluoc 'Fururrrr l ur sluedrcl lrEd .I alqel 86I dululDt,L 194 Training Table 2. Resea rch fellows a n d scholars, cont inued IITA Degree Name Country University supervisor pursued Field of Study 5. J.A. Otoo Ghana University S.K. Hahn PhD Effects of uhotoueriod. of Ghana temperature and growth regulators on flowering, fruiting and seed setting and germination of cassava. 6. S.B.C. Wanki Cameroon University of Kaung Zan PhD Mineral nutrition and soil Ihadan, Nigeria fertility of upland and lowland rice on the Plain of Ndop, Cameroon. 7. D.A. Shantron United Cornell University, E.A. Kueneman PhD Adaptation of soyheans of States United States differential mdturity to semiarid environments in Nigeria and soybean response to fertility. 8. F.N. Anno-Nyako Ghana University of G. Thotta- PhD Characterization of viruses. Science and P P ~ I I Y Technolorv. Kumasi, Ghana 9. S.K. Asiedu Ghana McGill Universitv. E.R. Terrv PhD Resistance tu bacterial bli-e ht in Canada CBSSRVR. 10. K. Atta Krah Ghaila University of G.F. Wilson I'hU Management of Leucaena for Thadan, Nigeria production of stakes, fuel, wood and leaf nitrogen and its potential in food crop production. 11. J.1,. Kiazolu Liheria University of B.T. Kang I'hD Phosphorus and varietal Arkansas. interactions in pluvial and United States hydromorphic rice. 12. J.A. Ayuk-Takem Cameroon University of V.1,. Asnani, PhL) Relationship of maize genotype Ibadan, Nigeria Y. Efron and altitude in Cameroon. 13. C.F. Yamoah Ghana University of M. Ashrnf PhD Field studies of Cliricidia Ihadan, Nigeria sepium. 14. M. Armtm Nigeria University of R. Lal PhD Soil erosion hazard in eastern Ihadan, Nigeria Nigeria in relation to soil properties and land use. 15. L.T. Ogunremi Nigeria University of' R. La1 Phll Soil moisture extraction Ibadan, Nigeria patterns. 16. Mhe-Mpic Mafuka Zaire Catholic University A.A. Ayanaba, Doctorat Survival and competitiveness of of Louvain, K. Mulongoy cowpea rhizohia. Belgium 17. M.E. Ogula Zaire Faculty Institute R. Lal, Doctorat Soil-water extraction and root of Agricultural K. Alluri system development of' rice in Sciences. relation to cultural practices. Yangambi, Zaire 18. C.A. Mha Nigeria Technical University of %E. Ezumah. PhD Intercro.~. u i. ngof cassava and Berlin. West ~ e r m a n y B.'I'. Kang cowpeas. 19. N.O. lwuafor Nigeria Ahmadu Bello B.T. K a n ~ . PhD C r o r~es ldue management. University, A.S.R. Juo Nigeria 20. N. Sanginga Zaire Faculty Institute A.A. Aynnaha, Iloctorat Nodulation of Leucaer~aa nd its of Agricultural K. Mulongoy contribution to the nitrogen Sciences, status of the soil. Yangamhi, Zaire 21. E.T. Eshett Nieeria Universitv of 1'. Ay, PhD Production potential and Ihadan, Nlgeria A.S.R. J u o fertility of soils from northern Cross River State, Nigeria. 22. M.B. Niyungeko Zaire Faculty Institute A.S.R. J u o Doctorat Micronutrient chemistry in of Agricultural tropical soils. Sciences, Yangambi, Zaire 23. R.K ayombo Tanzania University of R. Lal PhD Effects of' soil compaction and Dar~es-Salaam, crop response under reduced Morogoro, Tan- tillage systems. zania Training 195 Table 2. Research fellows a n d scholars. continued IITA Degree Name Country University supervisor pursued Field of Study 24. N.B. Lutaladio Zaire University of S.K. Hahn PhD Effect of diflerent planting Ibadan, Nigeria periods and associated agronomic practices on cassava performance in Zaire. 25. Wong Ting Fook Mauritius University of A.S.R. J u o PhD Nitrogen and water halance of' Reading, England maize and upland rice in the high rainfall tropics. 26. H.R.K. Franzen West University of R. Lal PhD Influence of tillage anrl bnftic Germany Gottingen, West on rooting pattern and yield in Germany an Alfisol in Nigeria. 27. U. Sahel- West Technical R. La1 PhD Soil erosion. Koschella Germany University of Munich, West Germany 28. I1.P.A. Unarnma Nigeria University of 1.0. Akohundu PhD Weed competition in yams Ihadan, Nigeria (Dioscorea spp.). 29. S.N. Utulu Nigeria University of 1.0. Akobundu PhD Persistence and movement of Ibadan, Nigeria herbicides in the soil. 30. J.E.G. lkeorgu Nigeria University of H.C. Ezumah PhD Use of two common Nigerian Ibadan, Nigeria vegetables (okra and melon) to maximize benefits from intercropped cassava and maize. Research scholars 1. Muimbn Kanko- Zaire University of S.K. Hahn MPhil Latent infection of Colleto- longo Ambayeha Ibadan, Nigeria trichum manihotis in cassava. 2. Idumho Kasele Zaire University of S.K. Hahn MPhil Effect of some environmental Nsongi Ihadan, Nigeria factors on cassava tuberization. 3. Kiala Kilusi Zaire University of S.K. Hahn MPhil Screening cassava for Ihadan, Nigeria resistance to cassava green spider mite. 4. Tomu Anota Zaire University of K. 1,euschner MPhil Clonal effect of some sweet Ibadan, Nigeria potato varieties on reproductive oerformance of C"vlas o.unti colis. 5. H.O. Nsaiama She Zaire University of H.R. Herren MPhil Biological control of cassava Ibadan, Nigeria mealybug, 6. Muyolo Gilumbu Zaire University of E.K. Terry MPhil Synergistic eflect of Ihadan, Nigeria Xanthomonas campestris pv. manihotis and Colletotrichum manihotis on cassava and assessment of potential yield loss. 7. S. Kundaiker United University of E.A. Kueneman MSc Soybean yield trials and Kingdom Reading, England soybean trap cropping experiments. 8. W.N.O. Hammond Ghana University of L.E. Jackai MSc Cowpea pests C. shadebi and Ghana C. tomentosicollis. 9. A.S. Ahissou Benin National University of 1.0. Akobundu Ing. Agr. Weed interference and control Benin i n hydromorphic rice. 10. A.B. Salifu Ghana University of S.R. Singh MSc Mechanism of flower thrips Ghana resistance in resistant cowpea cultivars. 11. G.B. Kouakanou Benin National University of J.M. Fajemisin Ing. Agr. Fusarium ear rot of maize in the Benin field and its postharvest predisposition of kernels to deterioration. 12. S. Dassou Benin National University of E.A. Kueneman Ing. Agr. Varietal differences in pod Benin pnhescence of soybeans and its relation to population suppression of pod sucking bugs. 13. D. Koudoro Benin National University of B.T. Kang, Ing. Agr. Evaluation of four woody fallow Benin C.H. ter Kuile species for alley cropping in a maize/cowpea annual rotation. 14. 0 . Adjadi Benin National University of B.B. Singh Ing. Agr. Inheritance of bruchid Benin resistance in cowpeas. 196 Tra in ing Tahle 2. Research fellows and scholars. cont inued IITA Degree supervisor pursued Field of Study M.S. Bjarnason Ing. Agr. Maize breeding. 16. M.C. Van der Belgium Catholic. University A.S.K. J u o Ing. Agr. Dynamics of soil organic matter Meersch of Leuven, Belgium under different cropping and fallow systems. 17. G. Moens Rclgium Catholic University M.N. Alvarez Ing. Agr. Sink repartitions in sweet of Leuven, Belgium potatoes. 18. J . Janssen Belgium Catholic Univer- G.F. Wilson, I n g Agr. Effect of mulch on the root sity of Leuven. A.N. Atta Krah system of plantains. Belgium 19. C Laloux Belgium State Faculty of G.F. Wilson, Ing. Agr. Growth of Desmodium Agr~culturaSl ciences, A.N. Atta Krah oualifoliurn in a pure stand and Gembloux., Beleium intercropped with maize. SO. X. Cornet Belgium State Faculty of K. Alluri Ing. Agr. Glume discoloration in rice. Agricultural Sciences, Gembloux, Belgium 21. M. Lohuschcr West University of P.A y M.A. Impact of agricultural Germany Bielefeld, West development projects un rural Germany development and effects nf socioeconomic changes on farming systems. 32. V.W.M. Moenikcs West, University of 1'. Ay M.A. Impact of agricultural Germany Bielefeld, West development projects on rural Germany development and effects of socioeconomic changes on farming systcms. 23. W. Nirmeyer West Umversity of P. Ay M.A. Impact of agricultural Germany Bielefeld, West development projects on rural Germany development and eEects of socioeconomic changes on farming systems. 24. K. Wuerdermann West Umvers~tyo f P. Ay M.A. Impact of agricultural Germany R~elefeldW, est development projects on rural Germany development and effects of socioeconomic changes on farming systems. 25. X. Zillikens West University of P. Ay M.A. Impact of agricultural Germany Bielefeld, West development projects on rural Germany development and effects of socioecono~nic hanges on farming systems. 26. J .P . Goff'art Belgium Catholic University D. I'erreaux Ing. hgr . Viability of Collrtotrichum of' Louvain, Belgium gleosporoides P. sp. manihoti.5. 27. S. Huke United Yale University, R. Lal MSc Soil erosion. States United States P R . B. Duguma Ethiopia University of B.T. Kang MSc Comparative study of root Ibadan, Nigeria systems of agraforestry species, seed collection and processing. 29. G.N. Ngala Cameroon University of Kaung Zan MPhll Studies of spikelct and panicle Ihadan, Nigeria fungal diseases of rice. 30. L). Birmingham United University of R.T. Kang MSc Determination of phosphate States Illinois, United requirements of early maturing States maize cultivars and early and intermediate maturing cowpeas. 31. B. Lame Benin National University D. Pcrreaux Ing. Agr. Cassava anthracnose discase. of Benin 32. T. Haug Switzcrland Federal Technical H.R. Herren Ing. Agr. Biological control of CM. High School, Switzerland 33. hlbulu Ntato Zaire Universi t ,~of H.C. Ezumah MSc Effects of mulching on cassava. Ibadan, Nigeria 34. B. Landu-Kalemha Zaire University of H.C. Ezumah MSc Timing of fertilizer application Ihadan. Nigeria in cassava. International Programs 197 Table 3. Numbers and countries of participants in out under these projects reported in the sections on IITA's non-degree-related training the various core programs. aroerams during 1982 Numher of Number of Mandated Research Country participants Country participants Cameroon.. . . . . . . . . . . 5 Mozambique . . . . . . . . . 1 The mandated research projects, of which there were Congo.. . . . . . . . . . . . . . 1 Nigeria.. . . . . . . . . . . . . 4 15 during 1982, used to be termed core-supplementing Ghana.. . . . . . . . . . . . . . 2 Sierra Leone . . . . . . . . . 2 projects because they extend the research of the India . . . . . . . . . . . . . . . . 1 Tanzania . . . . . . . . . . . . 1 Institute's core programs. Their new title under^ Jamaica.. . . . . . . . . . . . 1 United States. . . . . . . . . 4 scores the fact tha t these projects enahlc IITA to Kenva . . . . . . . . . . . . . . . 2 Zaire . . . . . . . . . . . . . . . . 2 carry out its mandated research more effectively. Seini-Arid Food Gra ins Resea rch a n d Development (SAFGRAD) Proiec t . In the CGIAK International Programs system,?^^^ is responsible for ma-ize improvement in Africa and has a worldwide mandate for improve- IITA provided much valuable assistance to national ment of cowpeas. The SAFGRAD project is an agricultural institutes during 1982 through its Office important part of IITA's effort t o fulfill those re- of International Programs. This office is responsible sponsibilities. The Institute has a plant breeder, two for planning, conducting and evaluating special agronomists and an entomologist a t Ouagadougou, research projects that are directly linked to the Upper Volta, working with the national, regional and o ther in terna t ional agencies involved in Institute's core program (consisting of the crop improvement, farming systems and training pro- SAFGlZAD to develop improved maize and cowpea grams) but funded through special contributions varieties and better cultural practices that a re from the Institute's donors. In carrying out this task, compatible with the farming systems of the semiarid the Office works very closely in all technical matters region. The SAFCRAD project has become the focal with the core programs. point for maize research in the semiarid regions Its overall objectives a re t o cooperate with of West Africa primarily because of its program national programs in the development of their for multilocational testing of maize germplasm. research capabilities, t o extend technology de- The project also has done much t o strengthen veloped a t IITA t,o national and regional research national programs through in-service and degree- centers (which then evaluate this technolo.e,v. and level training. adapt i t to fit their conditions), and t o obtain High yielding var ie t ies technology project. feedback that aids IITA researchers in planning This is a multilocational crop improvement program future research. for maize, rice, cowpeas and soybeans. In the The main objectives and activit,ies of the 22 special project's first phase, which hegan in Octoher 1981, projects maintained by International Programs dur- IITA researchers (including four agronomist / ing 1982 are described below under two categories: breeders, one for each of the four crops involved) mandated research projects and cooperative special carried out international testing and demonstration projects. You will find the results of research carried of high yielding varieties. During the second phase, Table 4. IITA Training courses conducted off site in cooperation with national agencies from 1974 through 1982 C-.n..x..l ntrv .." Course title Year Location Clientele Number of clientele Rice production 1974 Shendam, Nigeria Extension personnel 23 Nigeria Conducting coordinated 1976 Makeni, Sierra Leone Field assistants 47 Sierra Leone agronomic trials Rice production and con- 1976 Kenema, Sierra Leone Agricultural officers and super- 23 Sierra Leone ductine aaronomic trials intendents of eastern and southern regions Rice production and con- 1976 Fort Loku. Sierra A~riculturaol fficers and suuer- 18 Sierra Leone ducting agronomic trials Leone intendents of northeastern and northwestern regions and the western area Rice production 1976 Makali, Sierra Leone Peacc Corps volunteers 26 United States Extension officers 10 Sierra Leone Field surveying and data 1982 Bambui, Cameroon Extension field demonstrators 75 Cameroon collection (two courses) Maize and cowpea pro- 1982 Kamboinse, Upper Field extension personnel of the 15 Upper Volta duction Volta foundation seed production project Seed multiulication ~ersonnel 5 Benin 198 International Programs 24 national programs will participate in multiloca- Research o n nitrogen and phosphate ferti- tional testing to identify varieties that are suitable lizers in humid tropical Africa. This project is an for the various ecologies of tropical Africa. Many extension of research done by IITA's Farming technicians from these programs will receive in- Systems Program on soil management and cropping service training, and others will work toward degrees systems. The three soil scientists assigned to the in various agricultural disciplines. This project project are studying what happens to native and should markedly increase the pace a t which new chemically or biologically fixed nitrogen in the technology is developed for increasing rice, maize, cropping systems of the humid tropics and deter- cowpea and soybean production in tropical Africa. mining the amount of native phosphorus and the Research o n plantain production in Africa. requirements of external phosphorus in the soil of the The purpose of this project is to increase both the region. Their ultimate aim is to develop fertilizer productivity and longevity ofplantains, which are an management practices that will permit continuous important food in the humid forest zone and a key cropping by small farmers. They are also searching component in many of the region's cropping systems. for local substitutes for expensive imported phos- The project is staffed by a plantain agronomist and a phorus fertilizers. diversified crops agronomist. Drawing on research Maximizing nitrogen fixation by cowpeas and done by IITA's Farming Systems Program, these soybeans in farming systems i n t h e humid researchers are studying the physiology of sucker- tropics. To boost production of the protein rich ing, determining the effects of mulchand soilorganic legumes in the humid tropics, it is first necessary to matter on growth and yield, and establishing the increase the efficiency of nodulation and nitrogen multiannual yield potential of various cultivars. fixation in these crops. lITA is working toward that Much of this work is taking place a t IITA's high end in this project with the Boyce Thompson rainfall substation a t Onne, Nigeria. Institute (BTI) and Department of Soil Microbiology In a closely related project, scientists are concen- a t Cornell University (United States) and with the trating on the interaction between nutritional, University of Western Australia. The project is being ecological and hormonal factors in the regulation of carried out by 11 scientists from these organizations. sword sucker development and on in-vitro culture The scientists' principal activities are to investi- techniques for rapid multiplication of disease free gate the population size and diversity of types of propagating material. This work is taking place legume bacteria in the soils, to screen cowpeas and a t the Laboratorium voor Tropische Plantenteelt, soybeans in the field for high nitrogen-fixing ability, Katholieke Universiteit, Leuven, Belgium. to determine the potential for improving nodulation and nitrogen fixation through the use of inoculants, Accelerated research on biological control of and to identify superior cowpea and soybean lines t h e cassava mealybug and green spider mite. and rhizobia strains with high symbiotic potential as These two pests have become a serious threat in all well as soybean lines that can nodulate with the cassava producing areas of Africa. This project indigenous strains of rhizobia. These soybean lines was created so that IlTA could work more quickly on are being used in a breeding program to combine the biological control of them. Institute scientists have nodulating character with other desirable character- carried out an extensive survey in Latin America for istics. The project also includes a training program natural enemies of the mealybug and spider mite, that has attracted graduate students and postdoc- tested the effectiveness of those enemies, and toral fellows from Latin America, Asia and Africa. developed techniques for mass rearing and release of them. In the search fbr predators IITA has worked Improved agricultural research systems for closely with CIAT, the Commonwealth Institute of West Africa. This project, which is staged by an Biological Control (CIBC), and Empresa Rrasileira IITA agronomist and agricultural economist, will de Pesquisa Agropecubia (EMBRAPA). eventually consist of four parallel projects, three based a t national research institutes in Nigeria, On-farm, leucaena/maize/yam alley cropping Cameroon and Ivory Coast and a fourth, based at trials. This project was completed during 1982, and a IITA, that will coordinate the other three. The final report of its results is now available. The project project was created to bridge the gap between involved an llTA agricultural economist, farming research institutes and the agencies that transfer systems agronomist and soil scientist. Their objec- new technology to farmers. Its principal objectives tives included: identifying problems in establishing are to develop socioeconomic survey methods for and growing Leucaena leucocephala under farmers' pinpointing problems in farming systems or features conditions: testing the suitability of this.species as a of them that can be improved, to establish an planted fallow ; utilizing it as a source of yam staking adaptive research program at the farm level for material in the yam producing middle zone of translating research results into better production Nigeria; determining the performance of yam and practices that can be used by agricultural develop- maize alley cropped with leucaena; and finding ment projects, and to set up a system for getting farmers willing to help adapt this technology to their feedback from farmers to the national research conditions. institutes to help researchers plan future research. International Programs 199 The project will also provide training for African balance under various cropping systems of the high researchers and technicians in farm level adaptive rainfall tropics. Located at IITA 's substation in research. Onne, Nigeria, the project complements the Insti· Grain legume information center. The purpose tute's core research on soil fertility and chemistry of this project is to collect and distribute information and contributes to its goal of developing more about cowpeas and other food legumes on which effective fertilization programs and more efficient use UTA does research. The principal activities of the of nitrogen fertilizers. documentalist staffing the project are to locate Adaptive rice agronomic research. This proj ect literature on these crops, write abstracts of it in is providing IITA's Farming Systems Program with English, index the literature, set up a document an important opportunity for on·farm testing of its storage and retrieval system, provide a literature technology. In cooperation with the Bida Agri· search and duplication service to grain legume cultural Development Project (BADP), Nigeria, the workers, publish bibliographies, and encourage com· project's UTA agronomist is identifying agronomic munication among grain legume workers by means of problems through on·farm trials in the major rice newsletters, meetings and workshops. production zones with which BADP is concerned and Development of high yielding hybrid maize is assisting Nigerian extension workers in develop­ varieties for Nigeria. Two maize populations ing recommendations for farmers. developed at IITA- TZB and TZPB- have sparked a major t ransformation of Nigerian agriculture, Cooperative Special Projects particularly through the work of the integrated Like its 15 mandated projects, International agricultural development projects funded by the Program's 7 cooperative projects fall well within the W or ld Bank. Technology promoted by these projects scope of IITA's mandate and support the research of is being put into practice all across the maize belt of its core programs. The difference between these two Nigeria. What is needed now are high yielding maize categories of projects is that UTA does not seek hybrids so that the technology can be more fully involvement in the cooperative projects but rather exploited and growth in maize production sustained. undertakes them at the request of particular That is essentially the objective of this project, which governments or regional organizations. UTA helps will develop inbred lines that are adapted to tropical establish goals and provides the trained personnel conditions and from t hese produce high yielding needed to start the projects , and then trains national hybrids for the major maize production areas of scientists and technicians to assume responsibility Nigeria. The project is staffed by two breeders and a for the projects as soon as possible. pathologist/breeder. Food crops research within the ZAPI-EST Soil erodibility in relation to soil properties rural development program of Cameroon. IITA 's and management practices. The purpose of this contribution in this endeavor (the acronym stands project is to promote a better understanding of the for Zones d ' Actions Prioritaires Integrees de l'Est or soil fertility maintenance problems of the major soils Priority Action Areas of the East for Integrated in West Africa. The two scientists involved in the Development) is a five.year, three-phase research and project are investigating the erodibility of a wide training program. The aims of this program are to range of soils in Nigeria and the relation of erosion identify problems preventing increased food pro· susceptibility to basic soil properties. An important duction in eastern Cameroon, devise improved aim of t his work is to develop a means by which the methods that loca l farmers can use with the reo risk of erosion can be evaluated through r outine sources available to them, develop a plan for la bora tory analysis. Part of the work is being carried establishing crops research capability in this region, out at lITA and part of the State University of Ghent and to provide Cameroonians with research training in Belgium. at IIT A. Staffed by a farming systems agronomist, Root crops phytopathology research. This this project will give IITA a good opportunity to test project complements JlTA's breeding program in its improved r ice, cassava and maize lines for cassava, yams, sweet potatoes and cocoyams by pro­ adaptation to the humid fores t environment. viding information through basic phytopathological Food crops field trials and training program in research on the major diseases of these root crops. Siio Tome and Principe. Through this project lIT A Among the main activities of the project, which is is providing training and technical guidance to the staffed by an IITA pathologist/breeder and a path· Ministry of Agriculture of the government of Sii ologist at Universite Catholique de Louvain , are to Tome and Principe in testing and evaluating food find mechanisms of disease resistance and develop crop varieties and cultural practices. The project has rapid resistance screening methods. given UTA an important link with Portuguese· Efficiency of nitrogen utilization in farming speaking Africa and an excellent opportunity to test systems of the West African humid tropics. The the performance of improved rice, maize, legume and scientist involved in this project is attempting to root crops material in a tropical island environment. determine the amount of leaching and the nitrogen Of particular value was the chance afforded by this 200 Research Support project for IITA researchers to evaluate maize streak cereal crops that are suited to mixed and monocrop- resistant varieties under epiphytotic conditions. ping systems in the country's various ecological zones. The project also includes a program for testing Smal l f a rms farming systems research in Ghana. This project, which is located at Atebubu, improved varieties and cultural practices in farmers' Ghana, consists of two main phases: soil fertility fields and a strong training program that will provide management and improved crop production manage- Cameroonian technicians with on-the-job,t echnical ment. The former is concerned primarily with soil and degree-related t,raining. The project staff con- series characterization; fertilizer use eficiency; the sists of nine IITA scientists and one administrator. interaction of fertilizer, plant density and weeds and Root crops improvement p rogram i n its influence upon rice yield; and allcy cropping and Cameroon. Small scale farmers are the ultimate relay/rotation cropping trials. The crop production beneficiaries of this project, the purpose of which phase involves variety testing for yield, date of is to develop improved varieties and production planting and weed control trials, and cropping systems that will increase yields of cassava, yams. systems developed for yam, maize and rice based cocoyams and sweet potatoes in Cameroon. systems. The project has permitted useful field Cameroonians will also receive in-service and testing of land management practices developed by academic training so that eventually they can take IITA's core program. This testing has been par- over all aspects of the program. One of the project's ticularly worthwhile since the agroclimate of the main concerns is the cocoyam blightlroot rot project's location is very similar to that of Ibadan. complex, a major disease of Xanthosoma sp. (one of IITA's mandate crops) in eastern Nigeria and in Zaire nat ional cassava research program. IITA was originally invited to participate in this Cameroon. Through screening in Cameroon, re- searchers hope to identify resistant materials. They project to assist in developing cassava varieties for Zaire with resistance to bacterial blight and mosaic have also been testing and evaluating breeding disease. Because of the enormity of the threat from material of the four crops on which IITA's Root and the cassava mealybug and green spider mite, how- Tuber Improvement Program is conducting research. ever, the program's emphasis has been shifted to The project is staffed by a root crops breeder and an agronomist. control of those pests. The core program's work on mechanisms of resistance is strongly reenforced by the research carried out under this project. The Research Support Units ultimate aims of the project, which has a staff of The research and training programs a t IITA receive seven persons, are to help researchers in Zaire's essential services from a number of support units, National Cassava Kesearch Program increase the yield, resistance to diseases and insect pests, and including Farm Management, the Genetic Resources Unit, Virology Unit, Analytical Services Lab- nutritional level of cassava; to assist the national program in making new varieties and research oratory, Library and Documentation Center, and the Office of Public Affairs and Development, which results available to farmers; and to provide Zairian agricultural workers with in-service and degree-level includes the Communications and Information Office training. and Conference Center. Other units not reported on here are the Biometrics Unit and Physical Plant Food legumes in Upper Volta. With funding Services. from IDRC, the IITA cowpea breeder responsible for this project is working to develop a breeding program Farm Management for the development of improved cowpea varieties. These varieties must, among other things, be sulted The farm staff manages IITA's 1,000-ham ain research to mixed and monoculture as well as relay cropping facility a t Ibadan, its 80-ha high rainfall station at patterns in the Sudanean and Sahelian areas of Onne, and its 24-ha midrainfall station a t Tkenne. Upper Volta and other African countries. The project Cooperating with national research stations, the has enabled IITA to expand its cowpea lmprovement staff also provides support a t different locations in program to ~ncludet he Sahelian region and has northern Nigeria to enable IITA scientists to grow trials under various climatic conditions and soil provided a n important opportunity for IITA researchers to carry out genetic improvement of types. An additional task carried out hy Farm Management in 1982 was to assist IITA cooperative cowpeas in harsh, drought prone environments such as do not exist in Nigeria. projects in Upper Volta and Zaire in developing and improving their research facilities. Cameroon na t iona l ce rea l s r e s e a r c h a n d Farm Management provides research land, irri- extension. This project contributes to work being gates and applies fertilizers and pesticides. Scientists done in IITA's Cereal lmprovement and Farming are encouraged to mechanize whenever possible; Systems programs. I t was designed to assist mechanical planters are available, along with Cameroon's National Cereals Kesearch and mechanized spraying and harvesting equipment. Extension Prolect in the development of improved Farm Management gave support and technical agronomic practices and high yielding varieties of assistance to research being carried out within Research Support 201 Nigeria at Mokwa, Ilorin, Ikenne, Onne and Zaria. A installation of new irrigation pumps is underway. mobile unit consisting of a pickup truck and 26-ft This facility will improve irrigation of IITA's 40 ha of gooseneck trailer enabled the staff to transport farm dry season land. An ablution facility for farm staff' machinery to various locations, prepare the land, and an equipment wash slab are being built. apply fertilizers and plant IITA trials mechanically. New equipment was donated to the rice program by At Ikenne, a researchsubstation southof Ibadan that the government of Japan and to the grain legume is managed directly by the Farm Office, a program of program by- the EEC. Additional equipment was upgrading and improvement was undertaken. Early purchased by the Institute for field operations. The in the year, all roadways were realigned, and field machinery includes additional n~)-t i lpll anters. crop surface drainage was improved. A farm office, harvesting, threshing, mulching and cultivation workshop, and equipment storage facilities were equipment, prime movers and irrigation pumps for built with a grant from the European Economic dry season cropping. Community (EEC). Further land development and a Farm Management maintains all farm roads and bore hole for irrigation are planned for 1983. soil conservation measures on the research farms The staff a t Onne continued research on crop through its heavy equipment section. It also manages improvement and farming systems and made a three lakes at Ibadan, which provide both drinking number of improvements in its facilities. Upland rice and irrigation water to the site. Aquatic weeds are research was begun with the planning of an early and removed from the lakes with a waterweed harvester: medium maturing varieties trial, and construction this material is then spread on the research plots to commenced on an underground lysimeter building increase organic matter and improve soil conditions. for collecting information about the soil's chemical The farm's vegetable and fruit production unit properties. The staff was joined by a soil scientist, provides fresh, high quality vegetables and fruit to who took charge of the nitrogen project heing carried IITA staf as well as to the Institute's cafeteria and out jointly by IlTA and the government of the the staff canteen. The lakes are stocked withdifferent Netherlands. species of fish, which are caught by gill nets and also The substation is located in the humid zone of provide excellent sport fishing. The vegetable garden coastal Nigeria and was donated to IITA by Rivers and fishing units are self-maintaining; sales of pro- State in 1974. The facilities include five houses, six duce cover all inputs. offices, two laboratories, a maintenance workshop A land clearing and development conference was and machine shed, crop dryer and guest house. The held a t IITA during which primary forest was cleared work done there on soil fertility and chemistry, using bulldozers with shear blade and tree pusher agroforestry, plaintains, cassava, sweet potatoes, attachments. Additional land was cleared using maize, rice and cowpeas supplements that of IITA's manual labor and chain saws. four major research programs. The results of Farm Management staff contributed to all major research a t Onne are reported in the appropriate training courses and trained students in farm sections of this report. management and mechanization. The staff also A major accomplishment this year was the conducted many field t,ours and received numerous adoption of minimum and no-tillage systems by the visitors who showed interest in land clearing cereals, grain legume and cassava programs of IITA. techniques and minimum tillage farming. In these systems weeds are controlled by the use of knock-down and preemergence herbicides, and Genetic Resources Unit planting can be done with mechanical cone seeders specially designed to plant directly through a dead mulch cover. For hand-planted trials, small strips are Conservation and Distribution rotovated through the dead mulch, leaving the soil A major event for the genetic resources unit in 1982 between the rows undisturbed. Minimum tillage was the commission of a seed store operated a t 1 8 O C reduces erosion, maintains a mulch cover, eliminates for long-term seed conservation. The store is 7.3 m crusting and enables the soil to retain moisture wide, 4.6 m long, and 2.4 m high and has a capacity of better. 48,000 aluminium cans 99 mm high and 46 mm in Among the other projects completed this year a t diameter. Each can holds around 95 g of cowpea seed the Institute's main station was a grain handling and or 69 g of rice seed. IITA will store three to five cans of processing building with dryers and cold rooms cowpea seed (depending on the seed size) and two (funded by an EEC grant). The drying rooms were cans of rice seed of each germplasm accession for used to dry improved IITA maize seed, and the cold long-term conservation. Seed for storage is dried to rooms were used for seed storage. Equipment for less than 7% moisture content and permanently threshing, bagging, weighing, cleaning, treating and sealed in the aluminium cans. Under these storage handling improved varieties of seed has been ordered conditions, the seed is expected to remain viahle for and will be installed in 1983. 50 years or more. In this way germplasm, which is the A new workshop for repair and servicing of farm foundation forpresent and future plant breeding, can equipment has been completed and is being equipped. be properly maintained. Construction of a new irrigation pump house and Seed must have a germination rate of 88% or above 202 Research Support before i t is sealed in cans for long-term conservation. mechanical inoculation under normal field con- If the percentage germination of an accession is 85 or ditions indicated that whereas most of the 0. satiua below, i t is rejuvenated. During 1982,630 accessions was highly susceptible, most of the 0. glaberrima was of rice and 500 of cowpeas were sealed in cans and highly tolerant to this virus. Tolerance here means 1,049 accessions of soybeans in aluminium foil that plants are either symptomless or show only trace envelopes for long-term storage. symptoms and are fully fertile with no obvious The Genetic Resources Unit continues to assemble reduction in plant height after mechanical in- new germplasm to enlarge the genetic variahility of oculation, but that the virus can be detected by IITA's gene bank. During the year, 699 samples of serological testing or the ELISA technique. cowpeas, 122 of Bambarra groundnuts and 545 of rice Rice accessions that appeared to be highly tolerant were received. These included a donation by Institut in last year's test were retested this year in the dc Recherches Agronomiques Tropical (IRAT) and by glasshouse and screenhouse. Sixty-five accessions a national program of the Malagasy Republic and of 0. satiua and 30 of 0. glaberrima were confirmed samples provided by the International Board of Plant, as being highly tolerant. Two accessions of 0. Genetic Resources. IITA's gene bank now holds glaberrima appeared to be immune; serological 11,000 registered accessions of cowpeas, 1,504 of testing by a virologist showed no virus after African rice, 4,558 of Asian rice, 1,300 of soybeans mechanical inoculation. The studies also indicated and over 2,000 of other crops. This germplasm is that most of the tolerant accessions are upland provided to national scientists free of charge on varieties collected in Africa. request. Blast resistance screening. In 1982 the Genetic In response to 235 requests from 32 countries, the Resources Unit carried out a field screening test that Genetic Resources Unit distributed a total of 9,812 included 536 accessions of the African 0. satiua land samples of germplasm from its gene bank for re- races, 287 of 0. glaberrima, 20 varieties of 0. satiua search. In addition, a total of 216 kg of seed of 16 elite developed by the International Rice Research cowpea varieties and advanced cowpea breeding Institute (IRRI), 30 cold tolerant 0. sativa varieties lines multiplied by the unit were provided to IITA's from Korea and 15 blast differential rice varieties. cowpea improvement program for distribution to 34 The test revealed that most of these Asian varieties countries for international field observational trials. are highly susceptible to the local blast disease at Also, a total of 320 kg of seed of 30 variet,ies of IITA: 17 IRRI varieties (85%,), 21 Korean rice cowpeas, rice and pigeon peas was provided to varieties (707/,), 95 Accessions of 0. glaberrima scientists for experiments or to national development (330/,), 69 accessions of the African 0. satiua (13%,) projects for large-scale seed multiplication. and 6 of the blast differential varieties were found to be susceptible to blast (Table 5). Those varieties and M u l t i p l i c a t i o n and R e j u v e n a t i o n others with similar genotype are probably unsuitable Newly received germplasm or old germplasm that has for Ibadan or areas with a similar ecology. been depleted by use is grown for seed increase. It is not surprising that a low number of accessions Accessions that have a low percentage of germi- of the African 0. satiua germplasm were susceptible nation (below 85%,) are sown for rejuvenation. In in this screening test because they were selected on 1982, 1,700 new accessions of rice germplasm were the basis of no blast damage in field screening carried multiplied, and 350 rice accessions with a low per- out during 1980 and 1981. The experiment was first centage of germination were rejuvenated. The unit begun in the main growing season of 1980 with a also multiplied 643 new accessions of cowpea germ- sample of 1,132 accessions of 0. satiua germplasm. plasm and another 315 accessions depleted by use. In The susceptible ones were eliminated from the addition, a total of 2,937 accessions of cowpea germ- screening in subsequent years. The remaining 467 plasm, most of which had been multiplied in 1977, and accessions of 0. satiua were resistant to local blast 820 accessions of soybeans were rejuvenated. diseases in three growing seasons over a period of three years. These materials are likely to be resistant Evaluation and Uses of Rice Germplasm to prevailing races of blast in Ibadan. Rice yellow mot t le virus res is tance screening. S t e m borer resistance screening. The unit Rice yellow mottle virus (RYMV) is now widespread handed over 755 accessions of rice germplasm to an in Africa and could become a serious threat to rice IITA rice entomologist for stem borer (Diopsis cultivation in this region. IITA's ride breeding thoracica) resistance screening, and he selected 32 program has begun breeding for varieties with accessions with less than 10% infestation by this tolerance to this disease. As part of that effort, the insect. The materials selected will be retested for genetic resources unit screened rice germplasm for confirmation of their resistance. RYMV rrsistance and studied the variability of rice Agrobotanical character iza t ion a n d evalu- germplasm in its reaction to this disease. ation. Fifteen hundred accessions of rice germplasm Studies carried out by the unit last year on the were evaluated for up to 41 agrobotanical characters, reaction to RYMV of over 1,000 0. satiua accessions and the information gathered was updated by com- and 75 0. glaberrima accessions after artificial puter. Six 0. satiua accessions that had good Research Support 203 agronomic characteristics and outyielded a local Table 5. Blast disease reaction of rice varieties in a check were identified during 1982 field evaluations . field screening test. IITA. 1982 These rice accessions were handed over to rice Variety Score" agronomists for further evaluation. From its gene bank. the unit selected over 200 rice Blast daerential varieties varieties. including many typical upland types from AichiAsahi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O all over the world and varieties with superior HL1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O agronomic traits (such as the largest and heaviest Fugisaka . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 k'ukunishiki . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 panicles or resistance to blast) for evaluation in Ginga . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Cameroon's National Cereals Research and Exten- sion Project. which is being conducted by IITA and Hokkai189 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 funded by USAID . Feedback information from the Kanto51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 project indicates that some of the materials are Kusabal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 K1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 performing very well. both in terms of agronomic K3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 aspects and disease resistance . Further testing of the materials will be carried out in 1983. K59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 PiNo.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Shin2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 C h a r a c t e r i z a t i o n and Uses of C o w p e a Toridel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O Germplasm Yashiro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Agrobotanical characterization. The seed coat Control varieties color of over 5. 000 accessions of cowpea germplasm BG90-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H was evaluated and characterized this year . A wide OS-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 range of variability in this character exists in the IRRI varieties germplasm . Forty-two distinct seed coat colors and I R 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 patterns were identified. and their characteristics IR8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 will be described . The unit also evaluated 360 ac- IR20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 cessions of cowpea germplasm for 29 agrobotanical 1 ~ 2 .2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 characters and another 1.5 00 accessions for four IR24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 characters. In addition. studies on the stability and IR26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 suitability of cowpea descriptors were begun in 1982 JR28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ti and will be continued in 1983. IR30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Y IR32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Insect pest and disease resistance screening. IR36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 The use of cowpea germplasm has increased as IITA scientists have continued the search for better IR38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 IR40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 sources of resistance to insect pests and diseases for IR42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 use in plant breeding . A total of 7. 184 samples of IR43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 cowpea germplasm were distributed to scientists in 1 ~ 4 .4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 the crop improvement program for insect pest and IR46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 disease resistance screening during 1982. Of the 3. 683 IR48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 accessions that were screened for tllrips resistance. IR50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 six were identified as being resistant; their level of IR56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 resistance is higher than that of accessions identified IR52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 previously . Over 4. 000 accessions were screened for brucbid resistance. and two new sources of re- Korean varieties Milyong23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 sistance (TVu 11952 and TVu 11953) were identified . Kumkang Bae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Of the 461 accessions that were screened for MansukBae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 resistance to cowpea aphid-borne mosaic virus Milyang30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 (CAMV) and cowpea yellow mosaic virus (CYMV). Milyang42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 one (TVu 7941) was identified as being resistant Tae Baik Bae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 to CAMV. and two (TVu 5971 and TVu 7483) were Saekweng Bae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 found to be resistant to CYMV . Over 200 selected HengangWaxi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 accessions were screened for aphid resistance. and Baikwoon Waxi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 six sources of resistance (TVu 3272.9836.9914.9929. Chung Chung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 9930 and 9944) were identified . Of the approximately SurakBae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.0 00 accessions that were screened for resistance to Do Bong Bae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 pod borer (Maruca testulalis). 48 appeared to be ChinjooBae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 resistant in a preliminary test . They will be further Nakdong Bae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 tested to confirm their level of resistance.-N.Q. Ng Akibare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 204 Research Support Table 5. Blast disease reaction, continued number of' requests from universities and research Variety Score" Institutes in Nigeria were also handled by the laboratory. NongBaik . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Pargun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Akihikari . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Library and Documentation Center Norimna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Parkwang . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 The Lihrary added 3,600 monographs and 2,000 volumes of periodicals to its collection during 1982. Samsesung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 In December the Library's holdings consisted of Choopong . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 25,000 volumes of periodicals, 23,000 books, 4,000 JosxengTongi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 YsungnamJosrng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 pamphlets, 3,500 microform items, 1,600 slides and 33 HnnanJoseng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 audio-cassettes. In addition, the Library has over 6,000 reprints on specialized subjects such as yams, Milyang21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 plantains and cowpeas. Current acquisitions were KwangKum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 announced cvery month through two media: Selected Sarshacl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Minimikari . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . List ofPuhlications Received in the Lihrary and Grain 8 Parkoinr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Legume Current Titles. With Le Riz: Publications en Langue F ran~a i se "Varieties with a score o f 5 or above are considered suscrptihir. Disponibles d la Bihliothe'que de Z'IITA, we initiated Bascd un IRHI. 1980. Slnndord fi;oaiuatcon S,ystrm for.Rice, 2nd cdition. a series of bibliographical guides t o our French language collection. Another guide in the series, Virology Unit Kdpertoire despdriodiques en languefran~aisere Gus a la bihlioth@que,w as produced in 1982. Working with some eight crops and over 20 different Sponsorship of the International Grain 1,egumc viruses, the Virology Unit provides valuable re- Information Centre by the International Develop- search support to all of IITA's crop improvement ment Research Centre was extended by one year to programs. In general, the unit is responsible for July 1983. Two issues (Numbers 24 and 25) of the identifying, characterizing and devcloping suitable Tropical Grain Legume Bulletin were published and resistance screening and/or indexing methods for all distributed. Two additional numbers were in press. viruses t,hat are or may become a serious problem in The third volume of abstracts of t he world the crops for which TTTA 11as a mandate. For that literature on cowpeas was published during 1982. It purpose the unit gathers detailed information on the includes 1,850 abstracts, representing the literature epidemiology and ecology of the virus diseases published during the period 1974 to 1980. Substantial identified in those crops. work was done on the fourth volume, which will be All this information is considered in the context ready for publication in 1983. of changing cropping systems and agricultural practices in the tropics and of new varieties being devcloped for the region. I'otentially important Public Affairs and Development endemic virus diseases can t,hus he prevented from becoming serious threats to crop production, and Communications and Information brecding strategies can be adjusted to fit new The office distributed about 25,000 copies of major information about t he viruses. Thc results of IITA publications to 4,600requestors in 132 countries virology research carried out this year are reported in t he scct ions on IITA's crop improvement last year. Most publications were distributed free. programs. Nineteen IITA publications were produced a t the Institute and printed a t the headquarter's printing plant or abroad. They were: Analytical Service Laborat,ory .Tissue Culture: lmproved Cultivars for Africa's The Analytical Services Laboratory continued to National Programs perform routine analysis of soil, plant and water La culture de tissus: Des cultivars elites pour les samples. During 1982 the laboratory analyzed 9,030 programmes nationaux africains soil samples for chemical and physical properties. A A profile of IITA International Programs total of 7,535 plant tissue samples were analyzed for nutrient elements, and 1,701 tuber samples were analyzed for total and free cyanide. The number of IITA Le point de La recherche 1981 water samples analyzed for chemical composition IITA Annual Report amounted to 4,474. In addition, 514 animal tissue, IITA Research Briefs, Vol. 3, Nos. 1 and 2 blood and serum samples were analyzed for various Le Riz: Publications en langue franqaise dispon- elements. A t.ota1 of 108,829 assays were carried out ibles B la biblioth6qne de 1'IITA during 1982. Although the majority of samples came Cowpea (Vigna unguiculata L. Walp) Abstracts of from the lITA research programs, an increasing World Literature Vol I1 1974-1980 Tropical Grain 1,egume Bulletin, Nos. 24 and 25 Twenty-one r e sea~chs eminars were presented- An Appr:iisal of the Present Farming Systems of thc nine as a series with t,he cmt ra l thcmr. "IITA Atebubu District of' Ghana Rcseart:h AAdvanccsf or l*'ood Produttion 1ncrc;lscs." .Automated and Semi-automated Methods for Soil The Institute received 120 visiting groups: ranging and Plant Analysis fromprimary s(:hoi~tlo final year university students. Maize Production Manual Government agencies, service organizations and Tuber and Root Crops Production Manual other groups continue to visit the lnstitule regularly. Soybean Production Manual seeking information on new varieties and improved Cowpea Product,ion Manual technologies. Stage sur legumineuses i graines: Entomologie Stage sur legumineuses i graines: Pathologie A total of 31 news releases were issued during the year. The office also wrote and placed more than 15 articles and feature stories ahout the Institute and its work in magmines and newspapers. The Institute's puhlications mailing list was surveyed and a program to computerize the mailing system was initiated. The new program will allow the Institute to direct specific puhlications to users that most need the information. New printing equipment., including a one~color offset press, was ordered and has arrived. I t will be installed early in 1983. 1nfi)rnlal training in print,ing, photography and graphic design for z~griculturali nfhrm;rtion tech- nicians and midlevel administrators from Nigerian agricultural research institutes continues. Conference and Visitors' Center The Institute held or hosted 13 conferences and .wo C rkshops: ommunications Strategy and Planning work^ shop, 1 1 2 2 January 1982. CIAT/CIP/IITA Workshop on Germplasm Distri- bution and Quarantine Considerations, 28-30 April 1.98%. U SAIL) Agricultural Development Officers Con- ference, 10-14 May 1982. .Workshop on On-Farm Experimentation, 31 May 4 June 1982. W o r k s h o p on the Results of Agricultural Develop- ment Projects in Nigeria, 14-15 July 1982. OAUICUA Workshop on the CDA Research Initia- tive to Promote Food Production, 16 18 July 1982. Planning and Evaluation Committee for Cowpeas. 2. 4 August 1982. W orkshop for African Rhizohiulogists, 20-24 September l9XZ. .,Joint Meeting of Planning and Evaluat ion Committees for Make. Rice. Cowveas and Sovheans (CEC Project). 18-22 October 1985. FAOIIITA Expert C o n s u l t a t ~ o n o n Durable Resistance Breeding, 25-29 October 1982. First Meeting of the IITA/IRAT~ICltISATi~:TZ Fa rmine Svstems Network for Africa. 15 19 ~ovemb 'e r1 982. .International Conference on Land Clearing and Development. 22 26 November 1982. Cassava Mealybug and Green Spider Mite Work- shop, 6 10 Uecemher 1982. Appendix 1 : The Weather of August) or 18% below normal, with individual monthly departures ranging from -6'y0 in July to at IITA -32% in April and -33%, in ~ u g u s t . The moisture regime in the second season was in Recurrent periods of moisture deficit characterized some respects a repetition of that first the weather a t IITA in 1982: the total rainfall of A 5 0 . 8 . ~ra~in fall on 28 ~~~~~t (out of a monthly 907.6 mm (28% helow normal) was one of the lowest total of 75.6 mm) contributed to favorahle moisture on record. Insolation during the cropping season was conditions at of the ~h~~~w as again generally helow average, while mean temperatures little rain in the last two weeks of Septemher, which were hy and large ahove normal as a result of warmer was by intermittent drizzles with a total nighttime conditions. A summary ofthe climaticdata water yield of 11 ,I mm, cumulative rainfall for the is given in Tahle Al . month as a whole fell 65'y0 short of the mean (Figure Al). Conditions imuroved slir-r htly in the first half of' Rainfall and Evaporation October (Figure ~ 2 ) h, u t crop growth remained severely impaired. A final persis tant drought January was characteristically dry, with only 1.6 mm through the rest of the season led in many cases to of rain on the twentieth. An unusual succession of near crop failure. showers in the second half of February raised hopes of an early s tar t to the rainy season, hut instead the showers were followed by a prolonged dry period that Sky Conditions and Solar Radiation lasted through the first two weeks of March. Since Higher than normal insolation prevailed from evaporative demand generally was above 5 mm/day, .January through April, when departure in monthly early plantings mostly dried out. mean values peaked a t 18% ahove the long-term Total rainfall i n March was below average (-l0'%,) average. In spite of the low rainfall in May, increased hut was concentrated in the second half of the month, cloudiness during this period slightly reduced providing acccptahle moisture conditions a t the incident radiation. Near-normal values (departure, beginning of the first cropping season (Tahle A1 and +29/,) prevailed in June, hut cloudiness again Figure Al). Not until the second week of April, reduced values by 9'j6 in July and 6% in August however, was a positive water balance established, below the corresponding multiannual means. A and i t was quickly followed by two weeks of moisture similar trend was observed in October, following a deficit (Figure A2). ret,urn to above average values (+8%) in Septemher. This a l te rna te pat tern of brief intervals of Early arrival of the harmattan in December caused favorable moisture followed by more sustained mists in the early morning hours and haze during the periods of drought characterized much of the first, rest of the day. cropping season. The only exception was the four- week period from June until the first half of July, Temperature and Relative Humidity when weekly mean rainfall consistently exceeded moisture dcmand (Figure A2). Cumulative rainfall Daytime hours were cooler than normal exccpt in throughout the season stood a t 730.4 mm (at the end January, April, Septemher and Decemher. Minimum Table Al . Summary of climatic data, IITA, lbadan central station, 1982 Total Total Solar Relat.ive Mean rainfall, evapo~ radiation Temperature. OC humidity. 'X, Mean tem- relativc Month mm ration gm-cal/cm"/day Maximum Minimum Minimum Maximum perat.urc, 'C humidity, T, January . . . 1.6 153.8 February.. . 44.6 149.2 March. . . . . 92.7 173.9" April . . . . . . 87.9 153.5" May.. . . . . . 124.4 13:j.Y .June. . . . . . . 166.7 119.1" July . . . . . . . 136.9 97.4" August . . . . 75.6 88.9" Septemher.. 66.1 97.1" Octobcr.. . . 102.2 125.4" Novemhcr. . 8.9 137.1 Ilecember . . 0.0 145.6 ,'Values adjusted for days for whirl! n o daia were obtained uosmwi ' 7 ; ~.s paads p u ! .~raq 3!q qua1shaJd ay? jo aqrds u: 'xeaL aqqjo s.~al.tenbO M? qse1 ayq Yu!xnp L [ ~ I -na!q~ad 'pahlasqo uoy?xodnha uad jo sanluA xaMo1 L1qq811s a97 0 7 pa?nq!quoa s ! q ~. xaqtuahoN qdaaxa sqquom [[a U! a3nx"n ahoqe p a u ~ a m aL~l! prmny ah!qeIax unauI aq& ( - 'aln 7Jedap) Jalooa sxnoy am!qqqS!u oql axaM Lem u! L ~ u o.x aqmaaa(l puv [!~dv 'L~unaqad' L~vnuepU I ueaur m~aq-Yuol 3u1puodsa~xoaq aqq ahoqe unr[7 ax[~ruY u!Ysxaha '1'ZUl.lOU 3AOqW 'qSl3JqU03 U! 'aJaM 83lnqExadma~ Z X 6 I 'VJ,LI 'uo!le~adana puu [Iu,$u!eJ uwau L l y a a ~'Z Va .rnY!.q 4lUOW 3aa AON (30 das 6nv In? u n y ADW ~ d vJD W q a j u ~ p 208 Appendix Appendix 2 : List of IRAT, l n s t i t u t de Recberches Agronomiques Tropical (lnstitute for Tropical Agricu1tur;il Acronyms Research), France. IRRI, In t e rna t iona l Rice Research Ins t i tu te . ABU, Ahmadu Rcllo University. Nigeria. Philippines. ADPs. Agricultural Oevelopmcnt Projects. IRTP, Intcrnational Rice Testing Progmm. AICSIP. All-India Coortlinated Sorghum Improve- I~ S- N- AR. International Se1"vice for National Apr i~ ment Project. cultural Research, Netherlands. APMEPU, Agricul tura l Projects Monitoring, MIDAS, Managed Tnput,~a nd Delivery of' Agri- Evaluation and 1'l;mning Unit, Nigeria. cultural Services Project, Ghana. BTI. Bovcc Thomnson Institute, United States. NAFPP, National Accelerated Food Production CGI'AR: ~ o n s u l t ; r t i v e ( >roup on Internat ional Project, Nigeria. ilgricultural Research. NCRE. National Cereals Research and Extension CIAT, Centro Internacic~nadl e Agricultura Triipical Project, Cameroon. (International Ccnter for Tropical Agri~:ulture), NCRI, National Cereals Research Institute, Nigeria. Colombia. NGPC, National Grains Productiol~ Company. CIBC. Commonwcalt,h Ins t i tu te of Biological Nigeria. Control. NIHORT. National Tnstitut,e for Horticultural CIDA, Canadian International Development Agency. Research, Nigeria. CIMMYT. Centro Internacional de Majoramiento de NRCRI, National Root Crops Research Institute. Maiz v Tri-eo ,Ilnt ern;~tional Maize and Wheat Nigeria. Center), Mexico. ODM, Ovrrseas Development Ministry of the United CIP, International Potat11C cnter. Peru. Kingdom. CNPAF, Nati(1n;rl Ccnter for Research on Rice and ORSTROM, Office dc la Recherche Scientifiquc et Beans, Brazil. Technique Outre-Mer (Overseas Agency for CNRA. Crntrc National de la Recherche Scientific and Technological Research). Agronomique (National Center for Agricu1tur:il PRONAM, Prl~gramme National du Manioc Research), Cameroon. (National Manioc Program), Zaire. CNRCIP, Cameroon National Root Crop Improve- SAFGRAD, Semi-Arid Food Grains Research and ment Program. Development Project, Upper Volta. EEC. Eurouran Economic Communitv SAREC, Swedish Agency for Research Cooperation EMBRAPA, Empressa Brasi l icra"de Pesquina with Developing Countries. Agropecwiria (National Agricultuval Research UI, University of Ibadan, Nigeria. Organization of Brazil). FAO, UNDP, United Nations Development I'rogramme. Food and Agriculture 0rg;rnization. GTZ, USAID, United States Agency for Tnternational Dcutsche Gesellschaft fiir Technischc Development. Zusammenarbeit (German Agency f i ~ rT echnical WARDA, West African Rice Development Cooperation). IAR, Association, Liberia. Inst.itute of Agricultural Research. Nigeria. IAR&T, ZAPI-Est, Zones d'Actions Priorit;~ircsI ntegrees de lnstitute of Agricu1tur:il Research and l'Est (Action Areas for Tntegrated Development in Training, Nigeria. ICRISAT. the E;~st,)C. amcroon. International Crops 1tesearc:h Tnstitute for the Semi-Arid Tropics, India. IDRC. International Development Resrarch Centrr. Canada. IFAD. International Fund . for Agricultural Develr~pment. IFDC, International 1"ertilizer Dcvelopment Cent,cr, United States. ILCA, Intcrnational Livestock Center for Aikica, Ethiopia. INTSOY, 1nternation:il Soyhean Program, Unit.ed States. IPO. Research Institute for P lant Protection, Netherl;~nds. IRA, Ins t i t u t dc la Recherche Agronomique (Institute for Agricultural Kescarch). Camer11(1n. Personnel 209 List of Personnel Grain Legume Improvement Program S.R. Singh, Ph.D., assistant. director and program leadur Administration V.D. Aggarwal, Ph.D.. plant breeder, Upper Volta E.H. Har tmans , PhU.. dircctor general S. Asanuma, Ph.D, microbiologist A. Ayanaba, Ph.D., microbiologist B.N. Okigbo. Ph.D., D.Sc., deputy director general (on sabbatical leave) M.B. Chitti-Babu, M.S., agricultural enginccr, Tanzania L.H. J. Hohenberg, Ph.D., soil microhiologist Shebeski. D.Sc., deputy director gmeral and interim L.E.N. Jackai . Ph.D., entomologist director of research E.A. Kueneman, Ph.D., plant breeder M.A. Akintomide, B.S., AICTA, dircctor of admini- N. Muleba. Ph.D.. agronomist, Upper Volt;r stration B.R. Ntare , Ph.D., plant breeder S.V.S. Shas t ry , PhU., director of research* M. Price, Ph.D., agronomist/breeder and acting project J.E.G. Haakansson, MBA, director of budget and finance leader, Tanzania B.A. Adeola, ACIS. accountant Y.S. Rathore , entomologist, Upper Volta K.A. Aderogba, FCIS, principal adnlinistrativc officer W.R. Root, I1h.D., agronomist/hreeder, Zaria. Nigeria C.A. Enahoro, administrative assistant to the director B.B. Singh, Ph.D., plant breeder general S.A. Shoyinka,I 3h.D., agrnnt~mist/hreederZ, aria. Nigeria E.A. Fox. M.S.. manager of information systems E.E. Watt, Ph.D.. plant breeder. Brazil 0.0. Ogundipe, ~.D.;rnedicalo fficer M.E. Olusa. assistant to director of administration E.A. Onifade, security superintendent Root and Tuber Improvement Program D.J. Sewell, dormitory and fond service manager S.K. Hahn, Ph.D.. assistant director and program leader R.O. Shovinka. B.S.. uersonnel manager M.N. Alvarez. PhD. , breeder S.J. ~ d o hA, M N I M , ' ~ ' ~ac~c,o~u ntant V. Bai, Ph.D., cytugeneticist R. Vick. MS. , manaper of infnrmation systems* F.E. Brockman, Ph.D.. agronomist and project l e a d ~ r , A. Yusuf, R S , contkller of stores Zaire Cereal Improvement Program F.E. Caveness, Ph.D., ncmatologist J.H. Chung, Ph.D., hreeder. Cameroon Y. Efron, Ph.D., assistant dircctor and program leader W.W. Fiebig, M.S., extcnsion agronomist. Zaire A.O. Abifarin. Ph.D.. IITA liaison scientist, Liberia R.D. Hennessey, Ph.D., entomokrgist, Zaire M.S. Alam, Ph.D., rice entomologist H.R. Herren, Ph.D., entmologist K. Alluri, Ph.D., rice agronomist/brceder K.M. Lema, Ph.D., entomologist J. Arrivets, M.S., R A T liaison scientist B. Loehr, Ph.D., entomologist, Paraguay V.L. Asnani, Ph.D., project l e a d ~ rU. pper Volta S.Y.C. Ng, M.S., tissue culturist M. Bjarnason, Ph.D., CIMMYT maize breeder S .J . Pandy, Ph.D., extension agronomist. Zaire J. Chung, PhD.. maize breeder, Cameroon D. Perreaux, Ph.D., pathologist Z.T. Dabrowski, Ph.D., maize entomologist H.J. Pfeiffer, I r . , agronomist and project leader'. O.P. Dangi, Ph.U., sorghum and millet breeder, Cameroon Cameroon L. Everett . I'hD., maize breeder G.L. Servant . MBA. administrative officer, Zaire J. Gibbons, t'h.D., rice breeder T.P. Singh. Ph.D.. hreeder, Zaire D.C. Goodman. MBA. administrator. Cameroon* A.M. Varela, B.Sc., entomologist, Paraguay T.G. Har t , Ph.D., chlef of party, Cameroon M. Veloso, physical plant services officer, Zaire D. Janak i ram. Ph.D.. rice breeder. Cameroon J.A. Whyte, L'h.D., hreeder, Camrroon J. ~ikafunda- wine, Ph.D., cereals agronomist , Cameroon D. McHngh, extension agronomist. Cameroon V.T. John , Ph.D.. rice pathologist F. Schulthess, Ing , entomolog~stF. A0 associate expert F.H. Khadr , Ph.D., maize breedcr. Zaria, Nigeria S.K. Kim, Ph.D., maize breeder H.N. P h a m , Ph.D., CIMMYT maize breeder Research A s s o c ~ a t e Y.S. Rathore , Ph.D., entomologist, Upper Volta E.M. Chukwuma, breeder M. Rodriquez, Ph.D., agronomist, Upper Volta A.C. Roy, P11.D.. rice agronomist, Cameroon Farming Systems Program H. 'I'nl11.yrund. 1'11 I ) . . ~'.,I!~~.I.I.O,II .I. \'ttrm:tzucI~i,1 '11.l) V I C V pl,, -t<,I > ~ I - I ' C.H.H. t e r Kuile, Ph.D., assistant director and program K I I I I K K I II.~I.<,-1L.1,> 1 1 1 1 ~ 1 leader 1.0.A kohundn, PhD., weed scientist. Y. Arora , Ph.D.. soil scientist* Visiting Scientists M. Ashraf, I'h.D., agricultural economist J.M. Faiemisin. Ph.D.. maize hreederluatholocist. NCRI. E.A. Atayi, I'h.U., agricultural economist, Cameroon bada an, Nigeria P. Ay, Ph.D., socio-economist D. Makonnen . Ph.D., maize hreeder, A d d ~ sA baba R. Balasubramanian, Ph.ll., agronomist, Ghana University, Dire Dewa, Ethiopia E. Baryeh, Ph.D., agricultural engineer 210 Personnel d.0. Rraide, PhD., agronomist, Ghana Research Associates W.N.O. Ezeilo. B.S., agronomist, Nigeria M.O. Ajala, M.S., seed technologist, Nigeria H.C. Ezumah. Ph.D., agronomist A.O. Osunmakinwa, M.S., plant genetic resources C. Garman , M.S., agricultural engineer associate, Nigeria B.S. Ghuman, Ph.D., soil scientist* N. Hulugalle, Ph.D., soil scient.ist A.S.R. J u o , Ph.D., soil scientist Virology R.T. Kang. Phl l . , soil scientist W.H. Rossel, Ir., vlrologist T. Kosaki. Ph.D., soil scientist R. G. Thottappilly. Ph D., virologist Lal. Ph.D.. soil scientist J.M.W. van Lent, Ir., vlrologist T.L. Lawson, Ph.D., agroclimatolagist H.O. Maduakor, Ph.D., soil srientist D. McHugh, extension agronomist, Cameroon Vlsiting Sccentist S.K. Mughogho, Phl). . soil scientist K. Mulongoy, Ph.D., microbiologist H. Huttinga, lr., vlrologist, IPO, The Netherlands H.J.W. Mutsaers. Ph l l . , agronomist N.C. Navasero, R.S., associate agricultural engineer Analytical Services Laboratory D.S. Ngamheki. Ph.0.. agricultural economist J.L. Pleysier. Ph.D., head N.V. Nguu, Ph.D., agronomist, Cameroon F. Nweke, PhL)., associate economist P.S.O. Okoli. Ph.D., agronomist Library and Documentation Center O.A. Opara-Nadi, Ph.D., soil scientist J .A. Poku. Ph.D.. weed scientist S.M. Lawani, Ph.D., head R. Swennen, Ir.. plantain agronomist, Onne, Nigeria B.O. Adenaike, M.Sc., bibliographer* J. van der Heide, Ir.. soil scientist* F.M. Alluri, M.S., part-time hiblio~raphcr J. van de r Kruijs, Ir., soil scientist, Onne, Nigeria M.A. Aluko, bindery superintendent G.O. Ibekwe, B.A., principal librarian D. Vuylsteke, Ir., plant physiologist G.F. Wilson, Ph.D.. agronomist E.F. Nwajei, B.A., acquisitions librarian M.O. Odubanjo, B.Sc., cataloger Public Affairs and Development C . C esarini, I'h.U., socio-economist M.A. Gowman. weed scientist J.E. Keyser, B.S., assistant director F.M. Gatmai tan, Jr., senior graphic designer J.C.G. Isoba, M.S., communications ofticer, publications Associate Experts J.O. Oyekan, B.S., head, communications and information A.H.S. van Elsaude, Ir.. FA0 assoc~atce xpert, st~il R.E. Rathbone, M.S., editor* physics N.C. Russell, M.A., editor Training W.H. Reeves, Ph.D., assistant director G.A. Cambier, 1,ic.. translator/interpreter C. Puttevils, Lic.. translatorjinterpreter Physical Plant Services D.W. Sirinayake, Diploma, training officer A.P. Uriyo, Ph.D., training officer/agronomist J.G.H. Craig, assistant director E.O.A. Akintokun, research vehicles service officer D.J. Amaratunge, refrigerationlair conditioning service International Programs officer E.R. Terry. Ph.D ,assistant director A. Amrani, heavy equipment service officer E.F. Deganus, B.Sc., CAR, administrator A.C. Butler, building and site service officer F.O. Ogunyemi, FCCA, accountant O.O.A. Fawole, automotive service officer J.M. Fereuson. f'abricationlwnter utilitv service officer Farm Management D.C. Couper. B.S., farm manager (on sabbatical leave) M.O. Yusuf, construction/site engineering service officer S.L. Claassen, M.S., acting farm manager P.D. Austin. B.S., officer~in-chargeO, nnc, Nigeria P.V. Hartley, R.S., farm engineer Genetic Resources Unit N.Q. Ng, Ph.D.. head and plant geneticist Associate Expert M. Davids, Ir., plant scientist, FAO associate expert *I,eft during the year Collaborators 211 Collaborators H. Marai te , Chcf de Travaux. Lahoratuirc de Phyto- pathologie, Univers i t~C atholiquc de I.ouvain, Louvain- Grain Legume Improvement Program la-Neuve, Belgium J. Meyer, Lahoratoire de Phytopathologic, Universite A.E. Akinghohungbe, University of Ife, Ile-lfe, Nigeria Catholique de Louvain, Belgium M. Alexander, Cornell University, Ithaca, N.Y., USA 0.0. Okoli, assistant director and leader of hreeding. C.A. Atkins, University of Western Australia National Root Crop Researrh Institute. Umudike. B. Boutler , University of Ilurham, England Nigeria 0. Dina, NCKI, Ibadan, Nigeria F. Quak, head of virology unit. Research Institute for A.R.J. Eaglesham, Boycc Thompson Institute, Ithaca, Plant Protection (IPO), Wagmingen, The Netherlands N.Y., USA J .N. S a s s e r , principal investigator, International A.M.R. Gatehouse , University of Durham, England Meloidogyne Project, Department of' Plant Pathology, T.A. La Rue, Boyce Thompson Institute, Ithaca, N.Y.. North Carolina Sta te University. Raleigh, North USA Carolina, USA 0. Leleji, Samaru, Nigeria J. V a n A m e r o n g e n , project leader, DP /FAO\GhR L. Meyer, Catholic University of Louvain, Belgium "CIAM". Libreville, Gabon D. N. Munns, University of California a t Davis. USA D.B. Williams, team leader, FAO Root Crop Development J.A. Odehiyi. UI, Ihadan, Nigeria Project in the South Pacific E.O. Osisanya, UT, Ibadan, Nigeria L.A. Wilson, head, department of Crop Science, P.F. P r e v e t t . Tropical Products Institute, Slough, University of the West Indics, Trinidad England G. Quinn, Kaduna, Nigeria Farming Systems Program A.K. Raheja, Samaru, Nigeria M. Roesch, Maradi, Niger L. Ahialeghedzi, Meteorological Services, Lome, Togu Wilfred Schwiehert , GTZ project, Togo C.O. Andrews . Universitv of Florida. Gainrsville. R.J . Summerfield, University of Reading, England Florida, USA W.E. Taylor, Njala University, Sierra Leone J. Ahdullahi, Bida Agricultural Devclapment Project, Bida, Nigeria C.F. Bentlev, Edmonton. Alherta, Canada Root and Tuber Improvement Program P. Bur ingh, Wageningen, The Netherlands Michael Collinson, CIMMYT, Nairobi, Kenya M. A-As-Saqui, agronomist and head, Division of Field M. d e Boodt, University of Ghent, Belgium Crops, Central Agricultural Research Ins t i tu te , W. Ehlers , University of Gottingen, West Germany Suakoko, Bong County, Liberia M. Ezue. National Cereals Research Institute. Amakama O.B. Arene, program leader for cassava and pathologist, Station, Nigeria National Root Crop Research Institute, Umudike, T.A. Faseun. NIHORT. Ibadan. Nlecria Nigeria D. Gabriels , ~n ive r s i t ;o f Ghent, Belgium E.O. Asare , dean of Faculty of Agriculture, University of E.G. Hallsworth. University o f Sussex, England Science and Technology, Kumasi, Ghana H.E. J e n s e n , Royal Veterinary and Agricultural D. Boulter , Department of Botany, University of Durham, University, Copenhagen, Denmark England J a m e s Jones , University of Florida, Gainesville, Florida, A.I. Carpenter , UNDPIFAO, Ministry of Agriculture, USA Zanzibar, Tanzania D.N. Kalabari , Shell Nigeria, Warri H.R. Chheda, Department of Agronomy, University of P.R.O. Kio. Department of Forest Resource Management, Ihadan, Nigeria UI, Ihadan, Nigeria M.T. Dahniya, project leader of root and tuber im- D. Kohner t , Sociology Development Research Centre. provement, Njala University College, Njala, Sierra University of Bielefeld, West Germany Leone S. Mack, ILCA, Ihadan, Nigeria L.S.O. Ene. director and hreeder. National Root C r o ~ B. Mahimba, Faculty of Agriculture, University of Zaire B. Mamhani , Faculty of Agriculture, University of Zaire - P e r Mansson. Federal Cooperative Collepe. Ihadan, Control, London, England Nigeria D.T.P. Hernandez, sweet potato hreeding, Louisiana Pe te r Matlon, ICRISAT, Ouagadougou. Upper Vnlta State University, Baton Rouge, Louisiana, USA G.C. Mrema, Department of Agricultural Engineering. F. Iyamuremye, director general, Institut des Sciences University of Dar Es Salaam, T a n ~ a n i a Agronomiques du Rwanda, Ruhona, Rwanda P.R. Manrya, ARU, Zaria, Nigeria M. J a n s s e n s , plant breeder, lns t i tu t des Sciences U. Mokwunye, IFDC, Muscle Shoals. Alabama, USA Aeronomiaues du Rwanda. Rubona. Rwanda L.A. Nadi. ABU. Zaria. Nieeria R.A:D. J o n & director, Ride ~ e s e a r c hS tation, Rokupr, F.B. ~ d u b u k a',A nambra-Lo-world Bank Rice develop^ Sierra Leone ment Scheme, Nigeria B. Lu ta l ad io , co-director, Programme National du F.I. Nweke. Department of Agricultural Economics, Manioc (PKONAM), M'Vuazi, Zaire University of Nigeria, Nsukka, Nigeria S. Lyonga, coordinator, NationalRoot Crop lmprovement J.S. Oguntoyinho, Department of Geography, UI, Ibadan, Program, Njombc, Cameroon Nigeria 212 Collaborators A. Ohiri, NRCRI, Umudikc, Nigeria P. Ohuyon, Shell Nigeria, Warri, Nigeria 0. Ojo, Department of Geography, UI, Ibadan, Nigeria D.U.U. Okali. Department of Forest Management, UI, Ibadan, Nigcria T.A. Okusami , University of Ife, Ile-lf'e, Nigeria M.O. Oladeji, Federal Cooperative College, Ibadan, Nigeria J.A. Omueti . UI. Ihadan. Nieeria J.A. Oshakuade, ~ k ~ t ~ - h kAogcro~c ulturaDl evelopment Pro~ectN. l ee r~a U.R. P ~ I , ' A R U ,Z aria, Nigeria P. Reid, Ilorin Agricultural Development Project. Nigeria L o u c a s Savv ides , Bida Agricultural Development Project. Nigeria G.O- . Schwab, Ohio State University, Columbus, Ohio, Tl -s.n . A. Singh, University of Sokoto, Sokoto, Nigeria K. Smilde, Institute of Soil Fertility, Haren (Gr), The Netherlands J. Sumberg , ILCA. Ihadan, Nigeria R. Tour te , IKATIGERDAT, Montpellier, France J. v a n d e r Heide, lnstitutc of Soil Fertility, Haren (Gr), The Netherlands K. Vlassak, University of Leuven, Belgium P.L.G. Vlek, IFDC, Muscle Shoals, Alabama, USA A. Wild, University ofReading. England Genetic Resources B. Gar ree t , IBPGR consultant, Rome Italy P.M. P e r r e t , IBPGR West Af r~canr eg~ona lo fficer, Ouagadougou, Upper Volta J. Toll. IBPGK ronsultant, Rome, Italy Publications (:raps in Eustt'rn Africa. Proceedings o f n workshop, pp. 19 22. Ottawa. Canada: IDKC. Cereal Improvement Program Hahn, S.K. 1982. "Resrarch Priorities, T c c h n i ~ ~ uain~ds Accomplishments in Sweet Potato Rt.eeding at ITTA." In Kim, S.K., Y. Efron, J.M. Fajemisin and I.W. Ifout Crops in Eastern Africa. Procerdings of a workshol). Buddenhagen. 1982. "Genetic St,udy of Resistancc in pp. 23 26. Ottawa. Canada: TDRC. Maize to Maizc Streak Virus." In Agronomy Ahstrucl, Herren, H.K. 1982. "Cassava M ~ a l y b n gA: n Example of p. 72. Anaheim, California: American Society of lnternat ionnl Collahoration." BiorontroI Neuw ond hgrr~nomy. Information l(1). Kim. S.K.. Y. Efron. J. Sin.e~h. ., J.M. Faiemisin and M. Herren, H.R. and K.M. Lema. 1982. "Cassava Mealyhug Bjamason. 1982. "Ucvclopment of Two Early Maturing, I'irst Successful Releases." Bioronfrul News and Streak Resistant Maize Populations for Africa." IITA Informotion 3 : 186. l:il5. Ccntre Yield." In ISTRO Confertznc~P n~cet~dingpsp. . 111 117. Tntrrnacional cle Agriculture Tropical. Osijr,k, Yugoslavia: IS'rRO. Rossel, H.W. a n d G. Thottappilly. 1982. "Soyhean Lawson. T.L. a n d R. Lal. 1982. "Cmn Water IncrP apers 215 Lawani , 8.M. 1982. "On the Heterogeneity and Classifi~ llreeding for llurable Kcsistance to Disease and I'ests in cat ion of Author Self-Citations." Jou r r~a l o/ the AYrica, 26-~29O ctoher 1982,111'A. Ihadnn, Nigeri:~. American Soci<,f,yfo r Info~,nati,nS citv~ctz3 3(5): 281 284. S ingh , B.B. a n d S.R. S ingh. 1982. Brccding tbr inscct Lawani , S.M. 1982. "A Rcvicw of the Effects of Various resistance in cnwpea. Papcr presentcd a t American Agrnnomic P~.acticeso n Cereal Stcm Borer Populations." Society of' Agrrmomy Annual Meeting. 28 Nnvrmber- Tropical Pest Mnnuy~rncn2t 8: 266-276. 3 Dcccmbrr 1982. Anaheim. Ciilif.. USA. S ingh , S.R. 1982. IITA's cowpra improvemrnt proxram. paper presentcd a t Workshop on Variel.al Jmprovement Conference and Seminar of Upland Crops fur Intensive Crnpping. 15-17 April 1982, IRRI, Los Dafios. Phil ipp~nes. Papers Singh , S.R. 1982. Storage uf yr:~in legomcs wirh ref'ereilcc 1.0 small farmers. Pirpcr presented a t Workshop on Post Cereal lmprovement Program Harvest 1,osscs and Small Farmer Storage. 19 24 April Alluri , K. a n d M.S. A lam. 1982. Genetic research in rice 1982, New Ilelhi. India. a t the Tnternational Institute of Tropical Agriculture. Papcr read a t the 3rd FAOISIUA Seminar on Field Crops Root and Tuber Improvement Program in Africa iind the Near East. 6-24 June 1982, Nairobi, Caveness , F.E. 1982. Soil biological factors for higlrrr Kenya. yields of' root crops. Second West African Regional Hoot Alluri , K., A.O. Ahifarin, K a u n g Z a n a n d M.S. Alam. Crops Workshop, 27 J u n e 1982. Monrovia. Liheria. 1982. Varietal improvement in dryland rice a t the Caveness , F.E. 1982. Itoot-knot nematodes on cassava. Intrrnational Institute of Tropical Agricultiirc. Paper 16th International Nematology Symposium, 2 Septemher. rcad a t Upland Rice Worksliop. 4 8 October 1982, 1982. St. Andrcws, Scotland. U.K. Rouake. Ivory Coast. Fa jemis in , J.M., Caveness , F.E. 1982. Deforestation induced changes in S.K. K i m a n d M.S. A lam. 1982. ~lt:matodes oil populations. International Symposium on Rrcrding for durable resistance in trnpical maizc with Land Clcar inp a n d 1)evelopment i n re la t ion t o special rcfcrmt:e to maizc streak virus. Papcr read a t environmental P1.otection in lhc liumid and Suh-humirl I"AO/TlTA Expert Consultation on 1)ursblc Itcsistanre Tropics. 24 Novcmher 19X2,IlT.A. Ibadan. Nigeria. Rrccdrr. 25 29 Octnbcr 1982, ITTA. Ibarian, Nigeria. Cavcness , F.E. 1982. The evolutionary phasrs ol' TTTA Grain Legume Improvement Program research activities 1967-1980. International Progranl Scminar Scrics on IITA Research Advances for. Food Ayanaha , A. 1982. Microbiolngical ~.cscarcha nd thc 1'1.oduction Increases, 5 Fchruary 1982. IITA, Ihadnn. changc from shifting t o ronl.inuous cultivalion. Paper Nigeria. presented a t F A 0 Workshop on Shifting Cultivation: H a h n , S.K. 1982. llTA cassava research t o overcome t.he 'Teaching and Research a t the Univcrsity Level. .1-9 Ju ly constraints t o production and use in Africa. Proceedings 1982. Univcrsity of' Thadan, Ibadan, Nigeria. nf the wnrkshop un Cassava Toxicity and Thyroid: Ayanaha , A. 1982. The state of biotechnology in Al'lrica. Rcse:~rcha nd Puhlic Health Issue. :3l May-2 June 1982, with special emphasis on biological nitrogen fixation. Ottawa. Canada. I'ager presented at Symposium on Bintechnology in H a h n , S.K. a n d H.R. H e r r e n 1982. (:assavii mealyhug Developing Countries. 13-14 Octoher 19X2. 1)elSt.. The control strategy: IITA's apprnach. I'aper presented at Netherlands. NAk'PI' Workshop, NRCRI. 21-26 Fehruary 1982. Avanaha . A. a n d D.N. Munns . 1982. Acid-A1 tolerance Umudikc, Nigwia. He r r en , H.R. 1982. Recent advancus in the hiolagical rontrul nf the Cassava Mealybug (Phmacocrus manihoti XI11 lnternat innal Congress of Micrrrbirrlogy. 8 ~ ~ 1 3 Mat. Fe1.r.. Homoptcra: t'seuducoccidae). Paper pre- August 1982. Rostsm, Mass., USA. scnted a t t hc Second West .4fi.ican Regional Root Crops dackai , L.E.N. a n d S.R. Singh. 1982. Varietal r c s i s t a n r ~ Workshop, 27 dune-:! July. 1982. &lonrovia.L iberia. in the int.egl.atcd pest managcmc:nt ol' cuwpe;, pests. He r r en , H.R. 1982. Itevirw of sweet potato weevils. C,ylas I'apcr presentcd at International Workshop nn Crop spp. ((:nlcnptera: Curculionidile): distribution. hiology Rorcrs, 1 1 21 June 19X2, ICTPE, Nairohi, Kenya. and resistance mechanisms of sweet potato. Ipornoea J a c k a i , L.E.N. 1982. Cowpea iml)rovcmmt: the role nf balntos. cultiva1.s tn the wecvils. Paper presnrted at the i?ntomological research at the 1nt.ernational 1nsi.itute of Second Wcst African Regional Hoot Crops Workshop, Tropical Agriculture, Nigeria. Paper presented a t a 27 June-2 July. Monrovia. 1,ibcria. seminar. 13 December 1982, Iowa State Universit.y, H e r r e n , H.R. 1982.Ilistribntion and ecnnomic importance limes, Iowa, USA. of P . n~uniholia nd Mononychellus spp. in Africa. Paper S ingh , R.R. 1982. Sixty-day cowpm varieties. I'aper presented at International Workshop on Biological presentcd at the Amt,rican Society nf Agronomy annual Control and Host Plant Resist.ance to Control the meeting, 28 Nnvemher~3 December. 1982. Anaheim, Cassava Mealybug and the Green Spider Mite in Africa, Calif., USzi. 6 10 December 1982. IITA, Ihadirn. Nigeria. S ingh , R.B. a n d S.R. S ingh. 1982. Objectives and L e m a , K.M. 1982. La chocenille du manioc: organisation a c h i e v r m ~ n t so f 111'11 research on cowpras and d'un programme de luttlc hiologiquc a'llTA. Paper soybeans. Paper prescnted a t 3rd FAO/SII)A Seminar on prcsmted to conferei.cc at the Faculty of Agriculture, Field Food Crops in Africa and the Ncar Kast. 6-24 June National University of Zaire, 23 April 1982. Kisangani. 1982. Nairobi, Kenya. Haut-Zaire. Zaire. S ingh, B.B., S.R. S i n g h a n d L.E.N. dacka i . 1982. L e m a , K.M. a n d H.R. Herren . 1982. Rionornics of Cowpca breeding fur diseases and insect resistance. Phrnucoccus ma,tihofi, an introduced pest of cassava in Paper prescnted a t Expert Consultat.ion Conference on Africa. Paper prescnted at workshop an Riacontrol and 216 Conference Papers Resistance Breeding to Control the Cassava Mealybug 1)evclopment for Cumniunity Developmcnt Officers oS and Green Spider Mitc in Africa. 6-10 Decrmher. 1982. Oyo State. Septemher 1982, Ibadan. Nigrria. IITA, lhada' Nigeria. Babaji, G., R. L a l and A. Singh. 1982. Socio-economic Lema, K.M. and H.R. Herren. 1982. Rrlatiunshiv of' t n I I 1 1 1 . . l / ,~l l l , l l l , . , , l , . . factors i n relat ion t o soil degradation and crop t q , , :t production in Sokoto. IPIAS. SOS Project . 14 21 t i " . ! . , . r I;,>< \ , I ~ s ~ . ~ . I . , I I , ,.> , ,,,,,,,..<..I, ~ ' ~ , l t . , ,; t, ~ I ~ September 1982. ISM, Wageningm, The Netherlands. Cuccineilidae), two imported natural enemies i f the Ezumah, H.C. and T.L. Lawson. 1982. Evaluatiun of' cassava mealybug. Paper presented at, the International some c u l t u ~ apl ractices fhr better cassava produrtion. Workshop on Biological Cuntrol and Host P l an t P a p e r prescnted a t Na t iona l Accc l r r a t cd Food Resistance t o Control the Cassava Mealybug and the Production Program Annual Workshop, 21 16 February Green Snider Mitc i n Africa. 6-10 nccember 1982. IITA. 1982, NRCRI, Umudikt,, Nigel.ia. Ibadan, 'Nigeria. Ezumah, H.C. and J. McGuire. 1982. Competitive Perreaux. D. 1982. Studv of cassava bacterial bl irht relationships of intrycropped maize and cowpea ol' pathogenesis: Identification and characterization of a different maturi ty times. Papel. prescnted a t 2nd toxic substance produced by Xanthomonns cumpcstris National Meeting of Nigerian Soyhean Scicntist.~1. 8 20 pv. manihotis. Seminar. 16 December 1982. IITA, lhadan, February 1982, TAR, ARU, Zariii, Nigeria. Nigcria. Gnwman, M.A. and 1.0 . Akobundu. 1982. An evalual.ion of a rope wick wipcr for post-cmrrgence weed control in Farming Systems Program ilo~tillagem aize and cowpca. I'aper presented a t Annual Conference nf Weed Society of Nigeria, 29 Novembcr Akobundu, 1.0. 1982. Integrated wccd management in 3 Uecenlher 1982. Umudike, Nigcria. cropping systems in Nigeria . Paper presented at, Hartmans, E.H., B.T. Kang, G.F. Wilson and 1.0. Training Workshop on Farming Systems Research, Akobundu. 1982. Rrilr of plant.cd fallow in developing Federal Ministry of Science and Technology, 30 July- stahle cropping systcms. Paper presented 31 la ti no^ 4 August 1982. Benin City, Nigeria. amcrican Association of Agricultural Sciences meeting. Akobundu, 1.0. 1982. The status and cffectivcness of no- 24-26 June 1982, Clrapingo, Illcxiro. tillage cropping a t the smallholder farmer level in the Juo, A.S.R. 1982. Unclrrstanding Nigerian soils tlirough developing countries. Paper presented a t FAOjlWSS chemistry and minel.alogy. Paper prcsentcd a t Annual Expert Consultation un Wecd Management Strategies Conference uf Soil Science Society of Nigcria, 29 fur the 1980s in t h r LDCs, 6-10 Septemher 1982. FAO, Novembcr 3 Dccembcr 1982. Jos, Nigeria. Rome. Italy. Kang, B.T. 1982. Fertilizer use in multiple cropping Akobundu, 1.0.1982. An evaluation ofRonstar herbicide systems in Nigcria, Tanzania and Senegal. Paper for weed control i n upland rice. I'aper presented a t 11th presented a t FA0 Expert Consultation Meeting in Annual Confrrencc of the Wecd Sricnce Society of Fertilixer Use under Multiple Cropping Systems, 1-6 Nigeria, 29 Novemher-3 Decemher, Umudiku, Nigcria. Fe1,ruai.y 1982. New Uelhi. India. Armon, M.N., R. La1 and 0. Babalnla. 1982. Socio- Kang, B.T. 1982. Somc aspects of land development and economic and biophysical factors responsible fur managcment of low activity clay soils for food crop accelerated soil emsion in southeast Nigrria. Paper production in humid and suhhumid rcgions uf southern presented .st IFIAS, SOS l'rojrct, 14-21 Septrmht.r 1982. Nigeria. Paper presented at Farming Systems Rescarcli ISM, Wagmingen. The Netherlands. Workshop, Federal Ministry of Science and Technology, Arora, Y. and A.S.R. Juo. 1982. Nitrogen leaching from 30 July-5 August, 1982. NII"OR, Benin City. Nigeria. different fertilizer sources in iiumid and subhumicl Kang, B.T. and A.S.R. Juo. 1982. Effects of' furesl. rcgions of Nigcria. Paper presented a t Annual Con- c l ~ a r i n go n soil chemical pruprrtics and crop p r r l o r~ ference of Soil Science Society of Nigeria, 29 Novcmher- mance. Paper presented at Cm~fercnt:eo n 1,and Clearing 3 Decemhcr 1982, Jos , Nigcria. and Development. 22-26 h'ovemhcr 1982, 1ITh. Ihadtm. Ashraf, M. 1982. Basis for developing farming systems Nigeria. research in West Africa. Paper presented a t 1st work^ Kang, B.T. and A.S.R. Juo. 1982. Soil fe r t i l i ty sliop of the West Afvican Farming Systems 1teseari:h nianagemcnt and cropping systems for upland rice Network, 15-20 Novemher 1982, Thatlan, Nigeria. p roduct ion in West Africa. I'apcr prcsentcd a t Ay, P. 1982. I,arge scale projects and difficultips to learn IRRI/I DESS.A/UtATUpland Rice Workshop. 4 8 October t.licir lessons. Paper presented a t Confcrencc rm T,and 19x2, Rounkc. Ivory Coast. Clearing andUevelopment inRelation to Environmental Prrrtertirm in the Humid and Subhumid T~.opics2, 3 26 Lal, ll. 1982. Soiland waterconsrrvntiun and maiiagrment Novemher 1982. Ibadan. Nieeria. in the humid Lropic:~.P aper. presented a t PUGWASH Ay, P. Conference on Tropical Agriculture. .5 10 Ju ly 19X2. 1982. Options for appropriate information sources in farming.. s.y stems research. 1st Workshop of the Wcst Colombo, Sri Lanka. African Fnrnming Systems Kesrarch Network, 15 20 Lal, R., A.S.R. Juo and B.T. Kang. 1982. Chemical Novenlbcr 1982, lhadan, Nigeria. uppruacllcs toward improving water use efficiency by Ay, P., P. Reid, Yusef Isola, E. Adewnye, S.L. Atkins croos includine minimum tillnec. l'ao.c r .ur csentcd at. and H. Mutsaers. 1982. Technology test ing and International Conference on Chemistry and Wurld Food monitoring in farming systems researth : the preparation Su.u.v l i es -CHEMRAWN 11. 5~ 10 Decemhev 1982. of cm-fkrm experimentation Paper presented a t National Manila, Philippines. Workshop on Farming Systems Kesearch, 30 July- Lawson, T.L. 1982. Climatic factors fur higher yields of 1 Augrlst 1982, NIIWR, Benin City, Nigrria. root crops. Paper presented a t West AfricaRegionalRoot As, P. 1982. Illusions and hard lessons: thcdifficulties with C1.o~W orkshop, 27 June-2,luly 1982, Monrovia, Liheria. orientation da ta fbr priorities in agricultural rcsearcli. Lawson, T.L. 1982. Ileforestation and induced changes in Papel. presented at Workshop on integrated Hural mcsojmicro-climate. Paper presented a t Confermre on Land Clearing and Development, 23-26 November 19112. Ng, S.Y. 1982. Tissue culturv and rapid multiplicatior,: IITA. Ihadan, Nigeria. techniques and imporlance in distributing impmved Lawson, T.L., A.S.R. J u o a n d P. Ay. 1982. Methodology and/or resistant cassava clones. Paper presented at of farming svstems research: environmental de- International Wurkahop on Uiologieal i:ontrol and Host scriptions and vesource evaluation. Paper presented a t I'lant Resistance to Control Cassava Mealhug and tllc National Workshop on Farming Systems Kesearclr, 30 Crcen Spider Mite in Africa, li 10 1)ecernher 1982, IITA. July 6 August 1982, Rcnin City, Nigeria. Ibadan, Nigeria. Mah imba , B. a n d R. Lal. 1982. Socio-economic Ng, S.Y. a n d S.K. Hahn. 1982. Tissue culture of rout and constraints and soildegradation in Kivu region of Zaire. tuber crops a t the International Institute of Tropical Paper presented before IFIAS, SOS Project, 14 21 Agriculture. Papel. prcscnted a t West African Kcgional Septemher 1982, ISM, Wageningen. The Netherlands. Root Crop Workshop. 27 June 2 Julv 1982, Monrovia, Mulongoy, K. a n d A. Ayanaba. 1982. Evaluation of Liberia Rhirobiurn inoculants with field-grown cowpeas a t three locations. Paper presented a t NSM Annual Conference, Virology 26 30 January 1982, University of Benin, Benin City, Nigeria. Rossel, H.W. a n d G. Thottappilly. 1982. Maize Chlot.otic Stunt in Africa: a manifestation o i maize mottlc virus'? Mulongoy, K. a n d A. Ayanaba. 1982. Identification of Paper presented a t 2nd International .Maize Virus effective symbioses hetween cowucas and indeeenous Disease Colloquium and Workshop, 2 6 August 1982. rhizobia or endornycorrhiznl fungi in three soils. Paper Wooster. Ohio, USA. presented at NSM Annual Conference. 26-30 Januarv 1982, University of Benin. Benin City, Nigeria. Rossel, H.W. a n d G. Thottappilly. 1982. Latest rescarch results on root and tuber crop viruses and their indexing. Mulongoy, K. , A. Ayanaba, S. Asanuma a n d V. Ranga Par~epr resented a t Workshop oSTropicnlRout and Tuhcr Rao. 1982. Cowpea nodulation and response to Crop (iermplasm Distribution and Plant Quarantine inuculation in West Africa. Paper presented a t 1st Regultltions. 28-30 April 1982, IITA, Thadan, Nigcria. OAU/STRC Inter-African Conference on Bio-fertilizers, 22-26 March 1982, Cairo. Egypt,. Mutsaers. H.J.W. 1982. Institutional linkages in farmine Library and Documentation Center ~~~ systems research. Paper presented a t National Farming Ibekwe, G.O. 1982. The role of the lihrary in the Svstems Research Trainine Worksho'n . 30 Julv-4 Aueust ag~.iculturals ector of n nat.iun's ecr,nnmy. Paper 1982, KIFOR, Benin City, Nigeria. presented a t symposium of Oyo State Division uf thc Mutsaers, H.J.W. 1982. Aims, structure and organization Nigerian Lihrary Association cm "The Lihrary in the of a West Akican FSR network: some elements for Economy of a Nation," 12 October 1982, University of discussion. Paper presented a t 1st WAFSRN Workshop, Ihadan, Ibadan. Nigeria. 15 19 November 1982, lITA, Ibadan, Nigeria. Lawani , S.M. 1982. Technology transfer: what the Wilson, G.F. a n d R. Lal. 1982. New concepts for post literature says. Paper prcscnttd a t the 11T.2 Inter.. clearing land management in the tropics. Paper national Programs Scminar Series. 2 April 1982. IITA. presented a t Conference on Land Clearing and Ibadnri, Nigeria. Dcvelopmmt, 23-26 Novemher 1982, IITA, Ibadan, Lawan i , S.M. 1982. Issues in the mnnngcment of Nige~.ia. specialized Information analysis rmtres. Paper p r c ~ Wilson, G.F., T.L. Lawson a n d B.T. Kang. 1982. Basis sented a t the meeting of Specialized Information frrr defining benchmark areas and type of research to be Analysis Centres, 4 8 October 11182, Montehello, undertaken in West Africa. Paper presentcd at 1st Canada. Workshop of West Afvican Farming Systems Research Network, 15-20 November 1982, ITTA, Ibadan, Nigeria. Public Affairs and Development Oyekan, J.O. 1982. Nigcria and the Gwen Revo1utiun~-~ Training 1lTA's r.ole. Paper rcad a t Army Training Week of 83rd Reeves, W.H. 1982. Transfer. of t.cchnolr,gy: is the Division. Nigerian Army, 15-~19N ovember 1982, Army manpower capability available a t the national level? Headquarters, Enugu, Nigeria. Papcr presented a t International Programs Seminar O y e k a n , J .O. 1982. Agricul tu~.a ld cvclopment in Series, TTTA. Ibadan, Nigeria. Nigeria-progress and prohlems. Keynol.e adilrvsa at Uriyo, A.P. 1982. I'rogress in rcscarch drvrlopment of Agricultural and Rural Uevelopment I'roject Managc~ cassava and sweet uotato a t IITA. Pav.e r u. resentt?d a t :3rd mcnt Course, 13 December 1983, Administrative Staff ' FAO/SIDA Scminar on Field Crops in Africa and the College of Nigeria, Topo, Badagl.y, Nigeria. Near East. 6-24 June 1982. Nairobi, Kenya. Uriyo, A.P. 1982. I'rogress in the management of tropical soils at IITA. Pap.e r u.v esented a t 3rd FAOISIUA Seminar on Field Crops in Africa and the Near East, 6-24 June 1982, Nairobi, Kenya. Genetic Resources Ng, S.Y. 1982. Rice species in Africa and the germplasm collection, preservation, evaluat.ion and documentation programme of 1ITA. Paper presented during IDESSA/ IRRI/lRAT upland rice monitoring tour, 29 Septemher 1982, IITA, Ibadan, Nigeria.