AboutIITA The International Institute of Tropical Agriculture (IITA) is an autonomous, nonprofit corporation governed by a 15-member board of trustees headed by Dr. John J . McKelvey, Jr., of the United States of America. The Institute's chief executive officer is Director General Dr. Ermond H. Hartmans. lIT A seeks to develop alternatives to shifting cultivation that will maintain the productivity of the land under continuous cultivation in the humid and subhumid tropics; to develop higher yielding pest and disease resistant varieties of cowpeas, yams and sweet potatoes worldwide, and of maize, rice, cassava and soybeans in Africa, and to strengthen national agricultural research systems by a comprehensive training program and collaborative research. lIT A was established in 1967 by the FOi'd and Rockefeller foundations, which provided the initial capital for buildings and development, and the Federal Military Government of Nigeria, who allotted 1,000 hectares ofland for a headquarters site seven kilometers north ofIbadan. lIT A is one of 13 nonprofit international agri­ cultural research and training centers supported by the Consultative Group on International Agri­ cultural Research (CGIAR). The CGIAR is supported by the Food and Agriculture Organization of the United Nations (F AO), the International Bank for Reconstruction and Development (World Bank) and the United Nations Development Programme (UNDP). The CGIAR consists of about 50 donor countries, international and regional organizations and private foundations. IITA received support through the CGIAR from a number of donors, including Australia, Belgium, Canada, Ford Foundation, France, Federal Republic of Germany, India, International Bank for Recon­ struction and Development, International Fund for Agricultural Development (IFAD), Italy, Japan, The Netherlands, Nigeria, Norway, Organization of Petroleum Exporting Countries (OPEC) Fund for Agricultural Development, United Kingdom and the United States of America. In addition, other donors provide funds to lIT A to support specific research and training programs. Correct citation : International Institute of Tropical Agriculture, 1984. Annual Report for 1983. Ibadan, Nigeria Published by the International Institute of Tropical Agriculture, Oyo Road, PMB 5320, Ibadan, Nigeria IITA ANNUAL REPORT 1983 International Institute of Tropical Agriculture Contents Board of Trustees ....... . . .... .... ...... ............ . v Foreword ....... ..... ... . .. ... ....... ...... ..... .. .. ........ . Vl Cereal Improvement Program . .. ..... . ... ; . ... ......... . 1 Rice . . ........................ ..... .. .. . .. .. .... . . .... . . . .. . .. . . 1 Genetic Improvement . .... . .. ........... . . ; . . .... .. ... . ... ... . . 1 Entomology . .. . . . . .... .......... . . .. . . . .... . . .... ... ....... . . . 14 Pathology ...... . ...... : . . ... , . . ................... .. ... ...... . 19 Virology ... .. ... . .... . .... . .. , . . . ... .. , ... . , ........... . ..... . 22 Agronomy ... .. . ..... . . .... . ... . . .... .... . . . .. . . ............. . 22 Grain quality ..................... .. . . ...... . ......... . ...... . . 25 Maize .......... ... .. ................ . ..... ......... . .. . . . . .. .. . 26 Genetic Improvement ... ........... ................. . . .. ...... . 26 Entomology ............... . ................ , ..... ... ... . ..... . 39 Virology . ........................... .. ... .... . ... . ......... . . . 42 SAFGRAD Project ... " .... , . . .. , ... , . ... ... .. . , . . , . .. .. , ... . , . . 43 Genetic Improvement .. .... . ..... ........ ... .. , . . ... .... . ...... . 43 Agronomy .. , ... " .... . ". ... . . , .. .. .... . . . . . . " .... . . . , ..... , .. 46 NCRE Project, .... , .. .. . , ........ . ....... , ....... .. . , ..... . . .. . 51 Rice .... .. .. . ..... , ........... . .... ..... . . ....... . . , ..... , ... . 52 Maize. ... . .... . . . . , . . ..... ... ....... . , ... ...... . . , ...... .. .. . , 56 Testing and Liaison Unit. , .... , ............ . , ... . .. . .... . " .... . 61 Grain Legume Improvement Program ... . ......... . . ". 63 Cowpeas ......... . ... .. .... . ...... ... ... . . . .. . .... . .. .... ..... . 63 . Genetic Improvement .. .... . .... . . . . ... ...... . .... , ..... . . .... . 63 Entomology . ......... .. . . ........ .... ........ ... ......... , ... . 76 Pathology ..... ................. . ............ . ........... ... .. . 82 Virology ... . ............................... . ............. . ... . 83 SAFGRAD Project ..... . .... .... ......... .. ... . ............... . 84 Genetic Improvement .. . .. . ......... ' ........... . ". ...... .. . . .. . . 84 Entomology .. . ..... ......... ..... .. ....... .. ....... . ......... . 88 Agronomy ....... . ..... .. ... . . , ........................ .. .. .. . 90 IITA/EMBRAPA Program ........ " ................. . .. , ...... . 94 Soybeans ...... . . . . , .......... . ... . . ....... , ... .. , ... ... . , . .. . . 97 Genetic Improvement .. , . . . .......... . . , . ... ..... , . .... . .. " .. , , 97 Entomology ..... . .. .. ... , . . .. , ... , .. . . . .... , .... ... ... . . . , .. . " 101 Virology . ... .. .. . .. , .... , , ... ... .. , . ........ , . ............... , 102 Microbiology ..... , " ... .. " . " ........ , . .... . , ...... .. .... ... ... , . 104 Cowpeas, ......... , .. ·, . .. . " ... .... . , . ... , .... . .. ... . , .. "."., .. 104 Soybeans ......... " .. ... , .... "." . .... . , . . .. , . . . , . . .. .. . , . , ... , 105 Root and Tuber Improvement Program ........... , . ... 107 Cassava .. . . , .. . . , . ... .... ... . ....... ........ , .. . . . , , ..... . . . ... 107 Genetic Improvement . . .. . . , , ... . .. ... .. ... . .... ...... . , . : . , . ,. 107 Pathology . .. ....... . . ................ , . , . .. .. .. . . ....... , ..... 110 Virology . . . . ... . . . .. ... , . .. . .. . , . . . . ........ ' .' ......... , .. .. .. 111 Biochemistry .. , .. . , . . .. , ........... .. ............. . .... , . . . . .. 112 Biological Control. .............................. . .... , .. , ... , '. 114 Zaire National Cassava Program . . ... . ... . . . . , ................ , 123 . Genetic Improvement, .. .. ...... .......... . ... , . , ............ '. 123 Entomology .... . ....... , .. . .. .... .......... , ...... , .. . ....... . 124 Pathology .. . .. , ... .. ................. . ... . ......... ... ........ 126 Crop Management. , , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 126 yams ....... . ...... . ..... ... ... .... . .. . . . .... . . . . . .. . . .. . . ... .. 129 Genetic Improvement. . . . . . . . . . . . . . . . . . . . . . . . • . . . . • . . . . • . . . . . .. 129 Pathology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 130 Virology. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . 131 Sweet Potatoes. . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . .. 131 Genetic Improvement . ........ .. .. . . .... .. .. .. '. . . . . . . . . . . . . . . .. 131 Virology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 131 Nematology ........................... . .. .. .... . . .... . .... .. ... 132 Tissue Culture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 133 Root Crops Research in Cameroon . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 135 Cassava ............... . .......... . .....•....•................ 135 Cocoyams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . 136 yams ...... ·. . . . ............ . . .. . . . ........................ . ... 136 Sweet Potatoes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . 136 Farming Systems Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 139 Soil Management and Land Development .. . . . . .. . . . . . . . . . ..... 139 Characterization and Use of Wetlands .. .. .. . . . ....... . ..•. . .... . 139 Soil Degradation. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Organic Residues and Fertilizer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 Seedbed Preparation and Tillage .. ..... . ........................ 157 Land Clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 165 Cropping Systems and Management . . . . . . . . . . . . • . . . . • . . . . . . . .. 167 Multiple Cropping and Rotations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 167 Weed Management ................. ... .. .. . .. . ... . .. . . .. .. .... 170 Alley Cropping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . .. 176 Live Mulches and Cover Crops. . . . . . . . . . . . . . . . . . . . . . . . . . .• . . . . .. 184 Plantain Research. . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . 186 Farm Mechanization ................ • ........ .. . ......... : . . . . . 188 Cooperative Development. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 190 On-Farm Adaptive Research. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 190 Case Studies in OFA R. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 190 Analysis of Farming Systems . ...... . ..... . .. . ......... . ........ 191 Farmer and Consumer Surveys. . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . .. 192 Cooperative Research on Plantains . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 194 Cooperative Research in Rwanda . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 194 Training Program . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .. . . . . . . . . 197 International Programs . .... . ... . .............. ........... 201 Research Support Units .......... .. . .... . . .. ........ .. .... 203 Farm Management . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . 203 Genetic Resources Unit . . ........ • .... .... . .. . . .. . . .... ...• . '. .. 203 Biometrics Unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . .. 207 Analytical Services Unit .. .... ...... . ... .... ...... . ... . .... .... 207 Library and Documentation Center . . . . . . . . . • . . . . • .. . . . . . . . . . . . . 207 Public Affairs and Development. . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . 208 Appendix: UTA Weather ... ... : ..... . . . .. . . . .............. 209 Personnel. . . . . . . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . . .. 211 Collaborators and Trainees .. ....... ............. . . . . ..... 213 Publications ............ . . . . . ............... . . .. . ... .. .... . .. 215 Conference and Seminar Papers . . . ... . . ...... . . . . .. ..... 216 Acronyms . .............. . . . . . . . ............ . . . ... .... ..... . . 218 Board of Trustees Dr. John J. McKelvey, Jr. (Chairman) Rockefeller Foundation (retired), Richfield Springs, New York, U.S.A. Mr. D.E. Iyamabo (Vice-Chairman) Director, Department of Agricultural Sciences, Federal Ministry of Science and Technology, Lagos, Nigeria. Prof. Ango Abdulahi Vice-Chancellor, Ahmadu Bello University, Zaria, Nigeria. Dr. Gelia T. Castillo Professor of Rural Sociology, University of the Philippines, Los Banos, Philippines. Dr. Leopold K. Fakambi Executive Secretary, International Federation of Agricultural Research Systems for Development/Africa, Cotonou, Benin. Dr. E.H. Hartmans Director General, UTA, Ibadan, Nigeria. Dr. Hidetsugu Ishikura Director General, Japan Plant Protection Association, Tokyo, Japan. Dr. Klaus J. Lampe Head, Department of Agriculture and Rural Development, German Agency for Technical Cooperation, Eschborn, West Germany. Dr. E. de Langhe Laboratory of Tropical Crop Husbandry, Catholic University, Heverlee, Belgium. Alhaji M. Liman Permanent Secretary, Federal Ministry of Agriculture, Lagos, Nigeria. Dr. R.C. McGinnis Dean of Agriculture, University of Manitoba, Winnipeg, Canada. Mr. M.S.O. Nicholas Director, Agricultural Services Division, Food and Agriculture Organization, Rome, Italy. Prof. L.A. Wilson Dean of Agriculture, Faculty of Agriculture, University of the West Indies, St. Augustine, Trinidad, West Indies. Prof. T .M. Wormer Senior Agronomist, Royal Tropical Institute, Amsterdam, Netherlands. Foreword the management of cooperative research projects were combined under a new office. International lIT A has made steady progress over the last decade in Cooperation and Training. Second, all the units developing new agricultural technology to improve engaged in disseminating research information were the major food crops of the humid and subhumid consolidated to form the Documentation, Infor­ tropics and the farming systems in which those crops mation and Library Program (DIL). are grown. Both the IF ARD Congress and the External Review In recent years the Institute has expanded its confirmed that the Institute has developed a range commitment to aiding national and regional pro­ of viable solutions to agricultural problems and an grams in the vital task of adapting and transferring effective means in its training and cooperative pro­ that technology. lITA's chief contributions have jects for channeling those solutions through national been to supply these programs with the raw products research institutes into the farmers' fields. This of research-improved germplasm and promising Annual Report and its companion volume, Research techniques-and to share with them its scientific Highlights, document our most recent advances in expertise by offering training and by posting some of technology development and give examples of how its scientists in the national programs of various this technology has been made available to national countries. programs. The way was opened this year for new and stronger The Farming Systems Program has done so by links with these programs when lITA hosted in June expanding its on-farm research, which it conducts in the founding congress of the African Chapter of the cooperation with development projects. This work International Federation of Agricultural Research will ensure that component technologies developed Systems for Development (IF ARD). Attended by at UTA are tested and their adoption monitored in about 100 delegates from some 40 countries, the farmers' fields. meeting enabled UTA to introduce key African re­ The crop improvement programs have maintained search directors to its work and to obtain from them a their ties with national programs through inter· frank appraisal of its achievements. The participants national testing, among other means. Maize varieties found lITA's research highly relevant to the agri­ with streak resistance and improved cowpeas with cultural problems of their countries and expressed a multiple resistance to diseases and insect pests were strong willingness to work with the Institute toward widely distributed for testing this year. And on the solutions to these problems through cooperative strength of its success in test releases of natural research and training. enemies ofthe cassava mealybug, the biological con­ In September and October, the Institute was again trol team took important steps this year in organizing scrutinized by outside observers during a compre­ an Africa-wide program for control ofthis insect and hensive review organized by the Technical Advisory the cassava green spider mites. Committee of the CGIAR. Every five years each of The future progress of these efforts will depend on the international agricultural research centers must the readiness of national programs to work with us undergo such a review, in which a distinguished and on the generosity of donors in supporting this panel of specialists in agricultural research and work. To those who have already contributed their management examines the center's objectives, plans time and resources, we express our extreme grati­ and achievements. tude. We trust that their commitment to research is The panel's review of lITA management resulted fully justified and their hope for future successes in in several major changes. The position of research tropical food production strengthened by the results director was upgraded to that of deputy director reported here. general (research), and a more participative style of management was introduced through the creation of an executive management committee. Two types of $~~"f;u~ activity at the Institute were reorganized. First, in recognition of the importance of training in ERMOND H. HARTMANS strengthening national programs, this activity and Director General Cereal Improvement Prograr The cropping season of 1983 was very poor for cereal 82-2-3-2-3-1 and IR 4422-98-3-6-1 performed well, in production in many African countries because of addition to varieties reported in previous years. In drought and an epidemic of maize streak virus, which screening studies at Bende, Nigeria, ITA 239, 245 and was particularly severe in the savanna zone of West 247 were found to have a high level of tolerance to Africa. The Cereal Improvement Program has been iron toxicity. And in acid strip screening at Dnne, working toward a solution to the maize streak pro­ Nigeria, a number of upland varieties, including TDx blem since 1977 and was recently joined in this effort 1753-1-24, TDx 954-203-2-101, TDx 1012-12-2-1, ITA 117, by scientists of the International Maize and Wheat IR8192-166-2-3 and UPL(Ri-5), proved to be tolerant to Improvement Center (CIMMYT) in Mexico. low pH. Resistant varieties have been developed that are The potential threat to rice production of RYMV adapted to different ecologies and vary in maturity, and bacterial leaf blight was confirmed in a disease grain color and texture. These varieties are already survey this year, in which large scale infection by available to national programs. High priority should these rnseases was observed in some Sahelian coun­ now be given to mUltiplying and distributing seeds of tries. For the first time, RYMV was detected on the the varieties so that the problem of maize streak virus wild rice species Oryza longistaminata. in Africa can be solved. An important component ofIITA's rice work is the A major potential threat to rice production in rice improvement program of the National Cereals Africa is rice yellow mottle virus (RYMV). The Research and Extension Project (NCRE) in Cameroon. disease was first reported from Kenya in 1974 and by The program is currently emphasizing resistance or 1983 had also·been observed in Sierra Leone, Nigeria, tolerance to major diseases and low temperature. Niger, Mali and Upper Volta. Realizing the potential Several superior varieties and better management danger of RYMV, IITA scientists began to identify practices were found in trials conducted this year. It sources of resistance and over the past few years was determined, for example, that adjusting the time have incorporated this resistance into high yielding of planting may be a simple means of reducing sheath varieties, which will be available in the very near rot incidence at Ndop Plain .. future. IITA rice researchers strengthened their ties with In its efforts to develop stable, high yielding va­ national and international agencies in 1983. An rieties of rice and maize, the Cereal Program co­ agreement was signed establishing the Upland Rice operates with national programs and regional and Research Intercenter Coordinating Committee, international institutes that also emphasize resis­ which will coordinate a task force on blast research tance breeding for major diseases and insect pests. A in Africa and characterization of environments for similar effort must now be made to meet the urgent upland rice. The program continued to participate in need in Africa for drought tolerant varieties. international testing of genetic material by nominat­ ing varieties for programs of the International Rice Rice Research Institute (IRRI) in the Philippines and West African Rice Development Association (WARDA) in The main aim of rice improvement work at IITA is to Liberia. The program also maintained its close link identify superior high yielding varieties for upland, with the National Cereals Research Institute (NCRI) hydromorphic and low land conditions. Particular of Nigeria. IITA lines were tested in NCR!'s trials and emphasis was placed in the work this year on re­ those of the National Accelerated Food Production sistance to major rice diseases and insect pests, Programme (NAFPP). ITA 212 ranked first in the especially the ones that are specific to Africa, and on multilocational testing program ofNAFPP. tolerance to adverse soils. Several new upland selections, including TDx 936- 8-4-2-1,1768-3·1·1 and 1871-19-1, proved superior under Genetic Improvement dryland conditions; these lines also showed resis­ tance to blast. In lowland ecologies TDx 725-1·8·201-1, Upland Rice TDx 1838-1-3, TDx 1840-4·1, TDx 711-18·18, IR 13240· Among the major objectives of the Cereal Improve- 1 ~ Cereals ment Program are to develop high yielding varieties to Liberia for further evaluation 10 1984.-A.O. for the free-draining upland ecosystems of Africa Abi(arin and to evaluate existing materials under upland con­ ditions. Field evaluations of early generation and Multilocational trials'. The observational nur­ fixed lines were carried out at Onne, Ikenne, Ibadan, sery and observational, advanced and elite yield Horin, and Zaria in Nigeria, which represent different trials were conducted at five locations in 1983. climatic and edaphic conditions, and in Liberia and Standard cultural practices were followed at all Cameroon. Under the high rainfall, acid soil condi­ locations: conventional tillage; dibble planting at 25- tions of Onne, leaf blast (Pyricularia oryzae), sheath X 25-cm spacing, basal application ofN, P 205 and K 20 blight (Rhizoctonia solani), glume discoloration and at 60-60-60 kg/ha, followed by 30 kgN /ha broadcast 30 stem borers were the major biological stresses. At days after sowing; and application of the pre- and Ikenne, Ibadan, Horin and Zaria, drought was severe, postemergence herbicides preforan and propanil, occurring during the middle of the growing season followed by spot hand-weeding. The early maturing (July to August) at the first three locations, which ITA 257, medium maturing ITA 235 and as 6, a widely have a bimodal rainfall pattern, and toward the end of grown local variety, were used as check varieties in the growing season at Zaria. Leaf scald (Rhynchos­ all trials. The design of these trials was a randomized porium oryzae) and neck blast were the maj or diseases complete block. The elite yield trial was replicated observed at · Ikenne; disease pressure at Ibadan, four times, and the advanced and elite yield trials had Ikenne and Zaria was relatively light and variable. three replications. At anne the trials were conducted in a plot that had been in fallow for one year; N, P 20 5 Early generation materials. These materials and K 20 were basally applied at 30-60-30 kg/ha, were tested at four locations (Ibadan, Ikenne and followed by 20 kgofN applied three times (30, 50, and Onne in Nigeria and Suakoko, Liberia) during 1983. 70 days after sowing). An additional dose of 20 kg of Because of severe drought and related stresses during P 205 was applied at 30 days after sowing. 1982, only 133 F 3 lines and 317 later generation lines In the observational nursery, superior UTA fixed and introductions were selected and tested under lines and introductions were evaluated for their minimum irrigation at Ibadan during the dry season adaptability to different upland environments so that of 1982-83. Of these 181 single-plant selections and yield trials and varietal recommendations can be over 200 bulk selections were grown during the wet made to fit these ecosystems more closely. A total of season of 1983. The most promising fixed lines were 178 out of285 lines were selected at five locations to be advanced to multilocational variety trials. At Ikenne advanced to yield trials in 1984 or further assessed in 25 F 2 populations were grown in plots measuring 20 the observational nursery. Several new lines were X 5 m, with spacing of 40 X 10 cm and one seed per identified for the forest zone that were superior to the hill. Two hundred and forty single-plant selections checks in plant type and disease resistance (Table 1). were made based on drought reaction, earliness, Varieties for the savanna zone must be of in­ vigor, grain type, and thick and deep roots. These termediate stature and short duration, have high selections will be planted during the dry season at drought tolerance, and produce high yields. Lines . Ibadan, screened for resistance to blast and put into selected from TOx 936, TOx 1780, TOx 1857, IR 10068, multilocational trials in 1984.-J. W. Gibbons and IR 12631 were able to survive and produce grain At Onne, 160 early segregating populations and 350 at Zaria under severe drought. But no line having fixed lines, 65 ofthem introductions, were evaluated. growth duration less than that ofITA 257 (100 days) TOx 1757-1-28-201, TOx 955-212-2-102, TOx 960-62-2, was identified in this trial. Efforts will continue to TOx 891-212-1-201-1-101-201 and ITA 117 appeared develop very short duration upland lines adapted to promising for plant type, vigor and general tolerance this ecosystem. to blast and grain discoloration. In addition, 500 The 100 entries in the observational yield trial accessions from UTA's germplasm collection of were superior UTA lines and introductions chosen Oryza sativa from West African countries were evalu­ from previous years' trials. Many entries outper­ ated for their adaptability to high rainfall conditions formed the check varieties in yield or other charac­ at Onne. Thirteen accessions that had deeper and teristics at each of the three test locations; many thicker root systems than LAC 23 were selected from performed differently at the various locations. Seven these. Because of late planting, however, disease lines performed very well in this year's trial at Onne incidence was very low, and these lines will be (Table 2). reevaluated for disease resistance, grain quality and At Ikenne entries with growth duration of 130 to other characteristics in 1984.-K. Alluri 140 days gave higher yields possibly because they One hundred and pve lines from UTA and IRRI were in the vegetative growth stage during the long were screened at Suakoko, Liberia, to identify late drought. An introduction from the International maturing materials with tolerance to glume dis­ Center of Tropical Agriculture (CIAT), 11568, gave coloration for this high rainfall area. Fifty-nine lines the highest yield at Ikenne and showed good blast and were selected from 28 populations that were superior sheath blight tolerance at anne. But it is susceptible to LAC 23, the local check variety. These lines will be to glume discoloration and cannot be expected to multiplied at UTA during the dry season and returned perform well in areas of the savanna where pro!onged Cereals 3 Table 1. Pedigree, agronomic characteristics and disease reaction of rice lines selected from an observational nursery for the upland, forest zone, Onne, Nigeria, 1983 Glume Height, Duration, Leaf Neck Sheath discol· Line Cross em days blast blast blight oration TOx 936-81·6·3-101. ....... . . !R 1529/lguape Cateto 84 118 0 1 1 1 TOx 1010·5·3·1 ............. !RAT 13/Dourado precoce/TOx 494 102 116 0 1 1 1 TOx 1779·3-1·201 . . .. .. : .... TOx 1525/0S 6 112 124 0 1 1 1 TOx 1780·5·6·201·1. .. . .... . . TOx 1525//Norin 6/TOx 340 100 118 0 1 2 1 TOx 187·1·105 .............. TOx 504/IET 5854 118 130 0 1 1 1 19965 ..... .... ............ 4440//BG 9O·2/K8 80 132 2 3 3 3 Note: Disease reaction was rated. on sca1e oro to 9. Table 2. Performance of selected rice lines in the upland observational yield trial, Onne, Nigeria, 1983 Yield, Plant Duration, Leaf Neck Glum. dis· Sheath Entry kg/ha height, em days blast blast coloration blight TOx 1779-3-1·202·1 . .... • .. , ... , ...•.. • . ..... 2,950 119 133 1 1 1 2 TOx 936-79·5· 1. ........ • ..............•..... 2,690 96 127 1 1 1 4 !RAT 104 . . .......................... • ..... 2,670 119 125 2 1 1 4 ITA 187 ............. .. .... . .. . ......... . . . 2,410 121 128 0 1 1 4 TOx 1780·9·2·201·1 . .... . ..... .. . . . ... . .. . . . . 2,320 101 128 0 1 2 3 TOx 1010·6-3-5 . ....... . . . . . . . . ...... . ... . .. . 2,360 108 121 2 1 1 4· 11568 ................ . •.. .. . .....•.. . . .. .. 2,210 74 141 1 2 4 1 ITA 235 (check) ......... . . . .. . .. . ... . .. .. . . 1,620 106 116 2 1 5 4 LSD (5%) .... .. ....... ....... ....... ... ... . 830 C.V.,% ...... . ........................... . 29 Note: Disease reaction was rated on a scale oro to 9. drought occurs. ITA 187 and TOx 955·202·2·101 show· entries at a location minus the grand mean) was done ed high tolerance to glume discoloration and blast. using the Eberhart·Russel model to study the yield of TOx 1779·3·1·201, an OS 6 progeny of intermediate the selections across locations. Entries that respond height, produced high yields and exhibited good to more favorable environments (that is, have a resistance to the stresses in the forest zone. Selected regression coefficient (b) close to one) and have materials from the observational yield trial will higher than average grain yields are desirable. ITA continue to be evaluated in IITA and collaborators' 235, ITA 128, TOx 854·101·3·201·1·1·1, TOx 891·212·2· trials. 102·2·101·1, TOx 936·8·4·2·1, IRAT 170 and Sel. !RAT The advanced yield trial, which included 29 194 were found to be superior (Fig. 1). OS 6 was below entries, was grown at five locations. Because the average in yield and did not respond to more favor· rains ceased early at Zaria in northern Nigeria, only able conditions. TOx 936·8·4·1·2 gave above average the following varieties produced grain: ITA 128, ITA yields at all locations and had a regression coefficient 132, ITA 182, ITA 193, ITA 235, ITA 257, TOx 1871-19·1, slightly greater than one. !RAT 109 and DJ 12·539·2. The season was excep· The elite yield trial, the final stage in experiment tionally dry, and farm losses of crops such as sorghum station testing, contained varieties having character­ and 'millet were very common in the savanna. Mean istics that are considered superior for upland ecosys· rice yields were highest at Ibadan, followed by Onne, terns in Africa. The trial was planted at five locations, Ikenne and Ilorin (Table 3). The trial at Ibadan but data were obtained only at Ibadan, Ilorin and received supplemental irrigation during the peak of Onne. At Ikenne an early drought resulted in very the dry spell to ensure survival ofthe crop for seed. At poor seedling emergence, so the trial was abandoned. Onne rainfall was abundant, but other factors such as At Zaria only the early maturing varieties such as low solar radiation" diseases and acid soil were ITA 257, ITA 150 and IRAT 112 were able to produce constraints. grain. Several lines performed well across locations in The performance of the ten entries in the trial is this trial (Table 3). Three lines from the cross TOx 936 given in Table 4. The superiority ofITA 117 and 235 in (IR 1529/Iguape Cateto) were superior in yield. Lines these trials is evident from their consistently high from this cross were selected in 1980 for seedling yields. !R 5931·110·1 was damaged by blast disease in drought tolerance using a method developed at IITA 1983. Grain quality characteristics of these varieties (Annual Report for 1980). are given in another section of this report.-J. W. Regression of the yield of each cultivar at a loca· Gibbons, K. Alluri, N. V. Nguu, R. Dobson, M.S. tion on an environmental index (mean yield of all Alam, V. T . John, D. Akibo·Betts and Kaung Zan 4 Cereals Table 3. Performance of selected rice entries in an upland advanced yield trial at locations in Nigeria, 1983 Plant Duration, Yield, kg/ha Entry height, em days a Onne Ikenne Ibadan Ilorin Overall TOx 936-8-4-1-2 .. . ... . . . . .. ..... ... . . .. . . 92 125 2,570 2,130 3,230 1,650 2,395 TOx 936-8-4-2-1. . .................. ... ... 87 125 2,700 1,610 3,320 1,500 2,280 ITA 128 .. . .... . . ... . . . . . . . . . .. .... .. . . . 131 125 2,370 1,550 3,180 1,620 2,180 IRAT 170 ............... . ..... . ... . ..... 116 129 2,370 1,880 2,940 1,280 2,120 ITA 235 ..... ... ..... . . . . . ........ .. ... . 120 119 2,140 1,420 3,050 1,420 2,010 DJ 12-539-2 .. . ... .... . . . .. .. . .. ... ... ... 83 120 1,904 1,280 2,718 2,069 1,990 TOx 891-212-2-102-2-101-1 ....... . ......... 98 139 2,913 2,107 2,186 654 1,965 TOx 936-397-9-1-2 ...... . ..... . ... . . . . . ... 106 122 2,900 942 2,191 1,770 1,950 ITA 182 . ... . .. " . ... ... .... . ..... . ... .. 127 118 2,008 1,794 2,495 1,401 1,920 TOx 1871-19-1 ... . .... .. .... .. .... . . ... .. 106 122 1,870 1,910 2,770 944 1,875 OS 6 (check) . . .. . .... . .... .. . . .. . . . ..... 144 127 2,069 1,031 1,749 1,485 1,580 Mean .... ... .. .. .. . . . .. . ... . . . ...... . . ... . . . . . . ... .. ... . .... 2,140 1,521 2,404 1,230 1,850 LSD (5%) .... . . . . . .. ..... . . . ... ... .. .. .. . . : .. . . . .. .... . .. .. .. 440 684 826 782 C.V., 'Yo .... .. ..... . . . ..... . .. .. . . . ..... . .. . ..... ... . .. . .. . . . 12 27 21 38 "These data are from the trial at Ibadan. Screening for tolerance to acid soils. In parts of ammonium sulphate and muriate of potash, uniform humid tropical countries such as Sierra Leone, "acid strips" can be made and that by applying lime Liberia and Nigeria, rainfall exceeds 2,000 mmjyr and control strips can be made. Five pairs of control and is usually dependable enough for upland rice culti­ acid strips have been made at the Onne substation for vation. But production is often limited in these areas screening. Each is 200 m long and 4 m wide and because of soil acidity, which frequently leads to separated by a 2-m wide alley with a drainage canal. nutritional imbalances such as excessive aluminum In 1983 the control strips received 0.5 tjha of and manganese.a nd inadequate levels of calcium and dolomitic lime and 45 kg-P jha. Both the control and phosphorus. acid strips received 45 kgjha each of Nand K before Pot studies were conducted in 1982 with a repre­ planting, and 20 kg Njha was topdressed once at 20 sentative high acid soil at Onne, Nigeria, to de­ and again at 40 days after sowing. Seven hundred and termine the most beneficial combination of nutrients fifty cultivars were screened for tolerance to high . for growing rice. It was found that a balanced appli­ acidity. Each was planted across the 4-m acid and cation of all the nutrients under study (N, P, K, Ca control strips. The cultivars included introductions and Mg) is needed to promote plant growth and grain from three international trials coordinated by IRRI's yield .. International Rice Testing Program and from Since cultivars differ in their ability to grow and WARDA's Coordinated Varietal Trials, fixed lines yield in acid soils, screening and selection for toler­ from IITA's breeding program, and 77 cultivars ance to acid soil is being carried out at IITA's high selected from a 1982 screening at Onne. rainfall substation at Onne. The soils at Onne are of A total of 60 entries were selected, including IITA coastal sediment formation (Oxic Paleudult) with low test entries TOx 1753-1-24, 594-203-2-101 and 1012-12-2- pH and low base exchange status, leading to inherent 1, which showed high tolerance to acid conditions in low fertility . It has been found that by applying 1982 and this year as well. Among the elite ITA varieties, ITA 117 and 235 gave moderate yields, Table 4. Performance of rice entries in an upland elite compared to the check variety LAC 23 (Table 5). yield trial at locations in Nigeria, 1983 Selection was based on yields in the control strips and on the ability of the cultivars to maintain high yields Plant Dura- Yield, kg/ha ht., tion, Iba- in the acid strips. Cultivars that responded well to Entry em days Onne dan Ilorin Mean added lime were also retained. Plant height, maturity period and resistance to insect pests and diseases ITA 117 ....... 110 120 2,470 2,060 2,340 2,290 ITA 235 .. .. . . . 120 121 2,500 2,410 1,840 2,250 were also considered in the final selection.-K. Alluri ITA 118 . .. ... . 109 129 2,420 1,870 1,560 1,950 ITA 135 .. . . .. . 120 125 2,380 1,400 1,620 1,800 Hydromorphic Rice IRAT112 .. .... 98 110 2,010 1,230 1,840 1,690 Hydromorphic soils, including shallow swamp ecol­ ITA 141 . .... .. 114 130 1,920 2,070 750 1,580 ogies, are important rice growing environments in ITA 257 . . . . ... 90 108 2,140 540 1,750 1,480 OS6 ..... . .... 137 132 2,030 970 1,232 1,410 Africa. IITA 's breeding objectives for these ecologies ITA 150 .. . . . .. 109 110 1,980 160 1,940 1,360 are high yield potential, short to intermediate plant IR 5931-110-1 ... 102 125 1,570 140 2,240 1,320 height, resistance to lodging, medium to high tiller­ ing ability, good seedling vigor, resistance to blast LSD (5% ) ...... 350 767 800 C.V.,% .. . .. . .. 11 41 and tolerance to drought. Ability of the genotype to 32 perform relatively well under varying moisture re- Cereals 5 gimes is also an important trait for adaptation to Variety mean yield hydromorphic environments. Selected breeding ma­ 3,500 r---------------, terials and introductions are being screened at !ITA for these characteristics. Observational triaL In this trial entries in the 3,000 upland observational nursery were grown under hydromorphic conditions at !ITA. The trial was planted in July, and moisture was adequate through­ 2,500 out the experiment. Sheath rot, neck blast and glume discoloration were moderate. Sixty-two promising 2,000 entries were selected, including TOx 1779-3-1-201 and 16493, which performed exceptionally well. The former is intermediate in height and medium in 1,500 tillering and has slightly droopy outer leaves but erect flag leaves. In contrast, 16493 is short and high tillering. -J. W. Gibbons 1,000 Yield potential of lowland rice on hydromor­ 3,000 phic soils. An experiment was conducted to identify and characterize different types of hydromorphic soils. evaluate the yield potential of lowland rice in 2,500 this ecology and identify the production constraints of hydromorphic soils. Soils were characterized on the basis of soil morphological data and moisture on 2,000 the soil surface. Four soil types were observed: gley lowland soil, all horizon type (GLL); gray lowland 1,500 soil, all horizon type (GRL-ALL); gray lowland soil, underground type (GRL-UG); and gray-brown low­ land soil (GBL). In addition, a gravel phase was found 1,000 • where gravels made up mainly of iron-manganese concentrations and quartz appeared within 40 cm of 3,500·::=======~====~ the soil surface. In general, GLL is the wettest and most reduced and GBL the driest of the four types. GRL-ALL is slightly drier than GRL-UG. 3,000 Twenty plots covering the whole study area were planted with rice varieties IT A 212 and 222. The yields 2,500 of ITA 212 ranged from 0.6 to 7.1 tfha. The highest yield was obtained in GRL-UG, followed by GLL, GRL-ALL and GBL. The major yield constraints were 2,000 soil moisture (which is influenced by water-holding capacity of the gravel phase of the soil) and depth of groundwater table (Fig. 2). 1,500 The yield potential of 26 lowland varieties was evaluated on different soils ofthe hydromorphic field, which was divided into two blocks: A (flooded zone) 1,000 and B (not flooded but wet), each with three re­ -600 -200 0 200 600 800 plications. The depth of the groundwater table, measured at five points in the field, varied from 0 to 45 Environmentol index cm during the ripening stages of the crop. Grain Figure 1. Regression of yield on environmental index for yields ofthe entries ranged from 0.2 tlha for KN 144 in three rice varieties, lITA , 1983. block B.2 to 7.4 t for ITA 212 in block A.2. Yields of more than 6 t/ha were observed in the zone that was wet but not flooded on type !I and !II soils. Yields of area with less soil moisture.--K. Wasano and T. more than 7 tlha were obtained from ITA 212 and ITA Kosaki 230. IR 4422-98-3-6-1, Bouake 189, IR 46, ITA 123, ITA 231, ITA 222, ITA 236, ITA 239, ITA 253,19970,18447 Lowland Rice and Cisadane yielded more than 6 t/ha. The major objective of lITA 's lowland rice program is ITA 222, which is highly susceptible to neck blast, to incorporate resistance to important biological and was planted in all soil survey plots to determine environmental constraints into varieties with im­ environmental effects on incidence of the disease. proved plant type and high yields. This involves Severe damage from blast disease occurred in the introduction and evaluation of superior germplasm 6 Cereals Table 5. Grain yield and agronomic characteristics of lITA varieties in screening for tolerance to acid upland soils, Onne, Nigeria, 1983 Yield, t/ha Disease resistanceC Control Acid Plant Days to Plant Leaf Neck Grain dis- Sheath Variety /line plota plot height, cm maturity vigorb blast blast coloration blight TOx 1753-1-24 . . .... .. . .. . . .... .... 4.3 3.7 110 110 1 1 3 3 TOx 954-203-2-101 ..... . ........ .. . 3.8 3.0 105 120 1 1 3 3 TOx 1012-12-2-1 .......... . ........ 3.6 3.7 110 125 1 1 3 5 ITA 117 . .......... . ........ . ..... 3.0 2.8 115 115 1 1 1 1 3 ITA 235 .......................... 2.4 2.3 130 115 3 3 1 2 2 LAC 23 (check) ................... 2.1 1.9 158 134 1 0 1 1 3 8This plot was treated with lime. bPlant vigor was rated on a scale of 1 to 9, where 1 = very vigorous and 9 = very weak. cDisease resistance was rated on a scale of 0 to 9, where 0 = no incidence and 9 = very susceptible. and a hybridization and selection program. populations for selection on iron toxic soils. Some F 1 Resistance breeding is focused on rice yellow mottle populations of iron toxicity and cold tolerance cros­ virus, blast and stem borer (Diopsis thoracica). IIT A ses made early in 1983 had been advanced to the F 2 breeding lines and introductions are being screened generation for evaluation in 1984. The F 2 populations at Ibadan for resistance to disease and insect pro­ from 26 crosses oflowland with lowland and lowland blems, and testing for tolerance to iron toxicity is with upland varieties were grown, the segregating being undertaken at Bende in eastern Nigeria and materials evaluated, and final selection made at Suakoko, Liberia. Researchers in Cameroon are maturity based on plant type, grain appearance and identifying cold tolerant materials with resistance to reaction to diseases. A total of 96 plant selections rice blast and sheath rot. Initial evaluation of in­ were obtained from six populations. Because of the troduced germplasm, generation of breeding ma­ generally poor plant type and excessive height of terials and field testing for yield potential are carried most of the segregants, no selection was done on the out at IITA. rest of the F 2 populations. Early segregating materials. Several crosses Observational nursery. An observational nur­ were made using Gissi 27 and Suakoko 8 to establish sery composed of83 F 2 and advanced generation lines was grown in four-row plots 4.2 m long with hill Depth of groundwater level from soil surfoce (cm ) spacing of25 X 18 cm. A total of18 lines with short to intermediate stature and acceptable grain were selec­ 80r-------------------------------~ ted at maturity. Eight of the selected lines were uniform ; these were harvested in bulk for testing in the 1984 preliminary yield trial. Plant selections were made on the selected segregating lines for further 60 observation. Advanced yield trial. These trials consisted of 64 entries divided into two maturity groups, medium and late, each with 32 entries. In the medium maturity 40 group, the check varieties were Adny 11, BG 90-2 and IR 42 and in the late group, FARO 15 and IR 5. The trials were conducted under two fertility levels: 120- 90-60 kgJha and 60-60-60 kgJha ofN, P 205 and K 20. The 20 experimental design was a randomized complete block with four replications, a plot size of6.52 m2 and hill spacing of 20 X 20 cm. The performance of the entries selected from the medium maturity group is given in Table 6. In gen­ Of-L--- eral, the higher fertility level did not increase yields markedly. The selections that yielded more than 6 -10 tJha under both high and low fertilizer levels were TOx 1838-1-3, TOx 725-1-8-201-1, ITA 212, ITA 222, ITA -20 L....J._~ _ _L_ _'__~ __. l..__ _L_~~_...L....J 230, ITA 232 and ITA 234. Since their plant height is 26/8 7/9 19/9 30/9 7/10 22/10 2111 10/1116/1128/11 5/12 about 1 m or less and they mature in about 125 days Dote measured from sowing, these selections should be acceptable in Figure 2. Sequential changes in depth of groundwater table . many places where irrigated rice is grown. All the from the late tillering stages to rice harvest at different sites selections have long grains, although ITA 222, 230 in a hydromorphic field, IITA , 1983. and 232 tend to have chalky spots in the endosperm. Cereals 7 In the late maturing group, TOx 1840-4-1, TOx 711- Screening for Tolerance to Iron Toxicity 18-18, TOx 903-2-1, ITA 238, ITA 239, ITA 252,11373, 11975 and the check variety IR 5 gave the highest Field screening at Bende, Nigeria. Rice culti­ yields (Table 7). The introduced lines were in general vation in many areas is hampered by soil problems earlier maturing than the IITA lines, but they did not such as strong acidity, poor nutrient status, salinity yield as much. ITA 238 and 239, though late in and iron toxicity, the latter hei ng one of the most maturity, were among the entries with clear trans­ commonly reported problems of rice grown in inland lucent grains. Their tolerance to iron toxicity is given valleys of West Africa, South Asia and South in another section of this report. America. In order for these wetlands to be used for The best materials from the advanced yield trial are rice production, varieties with tolerance to iron nominated to national and international trials for toxicity and high yield potential need to be further evaluation, or potential varieties are used as developed. parents in rice improvement programs. In 1982 and 1983, lITA researchers monitored the iron concentration in soil solution in the Bende Elite variety trial. This trial included 28 entries valley, eastern Nigeria, and provided preliminary divided into early and medium maturity groups. It information on screening for tolerance to iron toxi­ was conducted in 7- X 5.2-m plots with four re­ city (IITA, Annual Report for 1982). The isoline map plications in a randomized complete block design. in Figure 3, which is based on data collected during The trial received N, P 205' K 20 at 120-90-90 kg/ha. The the growing season, shows the iron concentration in performance of selected entries is given in Table 8. In soil solution. The area with high iron concentration the early group, IR 2042-178-1, Taichung Sen Yu 285, was localized along the surrounding hill. The suscep­ KN 144, BPT 1235, Bouake 189 and the check variety tible variety IR 26 was used to assess the level of iron FARO 27 all yielded more than 5 t/ha. ITA 212 and 222 concentration as indicated by symptoms such as were the highest yielders in the medium maturity oranging and bronzing ofleaves. Iron toxicity scores group, each producing more than 6 t/ha. Both selec­ were based on IRRI's standard evaluation system for tions mature in 126 to 127 days and are earlier than rice. The area that is suitable for screening has the the check variety IR 42. In the advanced yield trials critical level of iron concentration of 50 ppm. The conducted last year, these two selections also yielded area where iron concentration was between 50 and 30 more than 6 t/ha and were the highest yielders among ppm had only slight toxicity, which may not be clear the test entries.-K. Wasano, T . Masajo and N. V. enough for screening. Nguu Table 6. Performance of medium maturing rice entries in a lowland advanced yield trial, UTA, 1983 Grain characters Yield, t/ha Growth du- Plant Length, Length-to- Variety/line 120 kg N/ha 60 kg N/ha ration, days height, em mma width ratiob TOx 1835-8-1. ........................... . ...... . 5.51 6.09 U8 104 3 5 TOx 1835-11-1 ..... ...... . .. . .... . ....... ... . . .. . 4.47 5.16 125 97 3 5 TOx 1838-1-3 ......... . ..... .. .. . ... '. . ..... . . ... . 6.54 6.36 124 102 3 1 TOx 711-16-1-1 ....... . ......................... . 5.17 131 U8 3 5 TOx 725-1-8-201-l. . . .. ... .. . ... .. .. ...... .. ..... . 6.35 7.30 125 101 1 1 TOx 714-1-204-1-101-3 .... . ... . .......... ........ . 4.78 4.71 124 llO 5 5 TOx 894-28-201-1-2 .. . ................... . ... . ... . 5.33 6.01 124 100 1 1 TOx 894-28-201-1-5 ..... . ....................... . . 5.37 6.08 123 93 3 1 ITA 121 . ....... .. .. ....... .... ...... . .... . .... . 5.34 6.36 123 94 3 ITA 212 . . ..... .. .... .. . ..... . . ...... . ..... . ... . 6.57 6.42 128 106 3 1 ITA 222 . ....... ... ...... , . ..... ..... ....... .. . . 6.39 7.47 127 97 3 5 ITA 230 .. . ........ . ..... . .. ...... . .. . .... ..... . 6.61 6.85 126 96 3 1 ITA 231 ....................................... . 5.24 125 102 3 5 ITA 232 ............................. . ......... . 6.53 6.45 125 102 3 1 ITA 233 ....................................... . 6.81 5.93 126 96 3 5 ITA 234 ....... . . . . ....... . ........ . ........... . 6.27 6.20 123 92 3 5 6838 . ... ... . .. .... . .... .... .... . . . .... ... ..... . 5.18 7.05 125 100 3 1 18447 ........... . .. . ....... ....... .. .. ... . .... . 6.69 127 106 3 1 ADNY II (check) .............................. . 4.93 125 95 3 1 BG 90-2 (check) ................................ . 5.77 6.43 127 102 3 5 IR 42 (check) . . ... . ... . . . .. .. ... ... . . . .. . .. . . . . . 5.07 5.85 135 101 5 5 Mean ............................... . . . .... .. . . 5.82 6.25 LSD (5%) ............ . ... . ....... . ............ . 1.30 1.18 C.V., 'Yo ....... .... . . . . ... .. ... ... ..... ... .. . .. . 13.7 11.3 "Length was rated on a scale of 1 to 7, where 1 = extra long a nd 7 = short. bLength·to-v:.idth ratio was rated on a scale of 1 to 9, where 1 = slender and 9 = bold. 8 Cereals Table 7. Performance oflate duration rice entries in a lowland advanced yield trial, UTA, 1983 Grain characters Yield, t/ha Growth du- Plant Length, Length·to· Variety/line 120 kg N/ha 60 kg N/ha ration, days height, em mm width ratio TOx 1835·12-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5.53 6.15 128 104 3 1 TOx 1836-1-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5.52 5.24 125 111 3 5 TOx 1840-4-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.85 6.89 138 118 5 5 TOx 711-18-8 ... . ... . . ... .. . . '. . . . . . . . . . . . . . . . . .. 5.44 6.09 143 108 3 5 TOx 711-18-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.27 139 110 5 5 TOx 711-18-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.27 6.23 137 108 3 5 TOx 903-2-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.06 6.99 124 100 3 5 TOx 725-1-8-201-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.24 5.85 125 106 3 1 ITA 238 ... ......... .. .......... . ...... . .. .. . " 7.08 6.34 140 117 3 5 ITA 239 ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.12 6.06 141 114 3 5 ITA 242 .... .. .. ..... . ... . .... .. ............ . .. 6.22 6.59 141 112 3 1 ITA244 . ... .... .... ... .... . ... .... ... ... . . . .. . 6.05 7.41 143 114 5 5 ITA 246 . . . .. . . . .. . . . . . .. . . . . . . . .. .. . . . . . . ... .. 6.36 140 118 3 5 ITA 247 .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.74 143 120 5 5 ITA 250 .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.74 138 113 3 5 ITA 252 ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.79 6.60 143 123 3 1 IR 4422-98-3-6-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.53 135 112 5 5 11373 . .. ... .. ..... .. .. ... . . . . . . . . . . . . . . . . . . . .. 6.21 6.04 127 102 3 1 11643 ..... . ..... . .... . ....... .. .. . .... . .. ... " 5.96 6.56 128 101 3 1 11975 . .... ....... . .. . . ... ... . . . . . . . . . . . . . . . . .. 6.29 6.16 132 103 3 5 16221 ... .. . ..... .... . ... . .. . ........ . . .. .... " 5.37 5.76 129 95 3 1 16493 . .. .. .. . . .. . .. . . . . . .. . . . .. . . . . . . .. .. .. . .. 5.49 126 105 3 5 18522 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.23 5.47 128 96 3 1 lET 6279 .......... . ..... ,. ....... .... . . ..... . .. . 5.97 6.53 140 113 5 5 FARO 15 (check) ... .... .... .. .. ... ....... . ... . . 5.42 6.00 142 122 3 5 IR 5 (check) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.24 8.00 135 110 5 5 Mean. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.08 6.35 LSD (5%). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.08 1.17 C.V., 0/0' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.9 11.1 Twenty-two rice varieties were included in the flooded. Two weeks later four three-week·old seed­ initial screening experiment conducted in the area lings raised in nontoxic soil were transplanted in the shown in Figure 3. Differences in tolerance between pots, along with one seedling each of a susceptible (IR the varieties tested are given in Table 9. Of the 16 ITA 26) and resistant (Suakoko 8) variety. The soil was lines, 8 (IT A 238 through 253) were selections from the kept constantly submerged. cross IR 5/Suakoko 8. The high yield potential and The test entries and checks were rated according to sturdy stem ofIR 5 and tolerance to iron toxicity and foliar symptoms of iron toxicity at 4, 8 and 12 weeks nonchalky grain characters of Suakoko 8 were sue· after transplanting. Other agronomic characters . cessfully combined in the test lines. The results were also recorded. Of the 72 entries screened, 28 were suggest that lines derived from crosses in which tolerant. Those having high tolerance, good panicle Suakoko 8 or Gissi 27 are one of the parents could exertion and clean grains were: TOx 960-72-1, TOm 2- possess tolerance to iron toxicity and should be 17, TOm 2-20, TOm 2-30 and TOm 2·65. evaluated further at Bende and other locations where there is iron toxicity.-K. Wasano, K. Alluri and T. Kosaki Pot and field screening in Liberia. A cooperati ve research project on iron toxicity was started in July by UTA, WARDA and the Central Agricultural Research Institute (CARl) of Liberia. For this project two pot experiments at Suakoko and Fendall and a field screening at Suakoko were conducted in 1983. The main objective of the pot experiment at Suakoko was to develop a reliable screel1ing method K for identifying lines tolerant to iron toxicity and then 0 .7 to screen test entries. x Soil from iron toxic sites was collected, dried, Figu're 3. Isoline map of Fe concentration (ppm) in soil thoroughly mixed, placed in 8-1 plastic pots and solution, Bende valley, eastern Nigeria, 1983. Cereals 9 The pot screening method was reliable because Table 8. Performance of selected rice entries in a both resistant and susceptible checks were grown in lowland elite variety trial, UTA, 1983 the same pot. It was noted, however, that thoroughly Days to Plant Length/ dried toxic soil had to be submerged for a long time Yield, matur- ht., Grain width before becoming toxic again. So, wet toxic soil should Variety t/ha ity em length ratio not be dried for pot screening. Early maturity A site with a serious Fe toxicity problem was ffi2042-178-1, .. . 5.48 127 107 3 5 chosen below the CARl darn at Suakoko, Liberia, for BG276-5 ..... . 4.38 114 114 5 5 field screening of90 entries. Three-week-old seedlings BG367-4 ...... 4.24 116 115 7 9 raised in nontoxic soil were transplanted in the iron­ Taichung Sen toxic field in three-row plots 3 m long. The experiment Yu285 . ..... 5.13 118 111 5 5 had a randomized complete block design with four KN 144 . ...... 5.67 126 116 5 5 replications. BPT 1235 ... .. . 5.24 120 101 3 1 Bouake 189 .... 5.89 131 113 3 5 Resistant checks Suakoko 8 and Gissi 27 and Kulu .. .... .... 3.29 120 133 1 1 susceptible checks IR 26 and IR 5 were planted across TE 52693 ...... 4.55 129 116 3 1 the test entries. Iron toxicity tolerance was rated on FARO 27 test lines and adjoining susceptible and resistant (check) ... .. 5.39 121 93 3 5 checks at 4, 8 and 12 weeks after transplanting ffi 36 (check) .. . 4.11 114 101 3 1 according to IRRI's standard evaluation system for Mean ......... 4.85 rice. Agronomic characters such as height, tiller LSD (5%) .. . .. 0.78 number, panicle exertion, grain discoloration and C.V.,% . . . .... 11.2 grain weight were also measured. Several entries with good plant type, panicle exer­ Medium maturity ITA 121 ....... 4.98 121 108 5 5 tion and grain characteristics and acceptable growth ITA 212 ....... 6.50 117 110 3 1 duration were found to be tolerant. The tolerant lines ITA 222 ....... 6.13 126 106 3 5 TOx 960-42-1 and 711-18-7 yielded more than Suakoko ITA 230 .. ..... 5.63 125 107 1 1 8.-A.O. Abifarin ITA231 .. . . ... 5.05 124 109 3 5 18447 .... ..... 5.39 127 117 3 1 BG 90-2 (check) 5.50 126 107 3 5 International Trials ffi 42 (check) ... 4.24 134 111 5 5 IITA's rice program maintains strong links with Mean .. .. . .... 5.43 other international rice programs, particularly by LSD (5%) ..... 1.01 conducting trials from IRRI and WARDA. These C.V.,% ... ... . 14.2 trials, which include entries from lITA , IRRI, Note: Length was rated on a scale of 1 to 7, where 1 = extra long WARDA, CIAT and various national rice programs, and 7 = short, and length-to-width ratio on a scale of 1 to 9, where promote rapid exchange and evaluation of elite rice 1 = slender and 9 = bold. germplasm and utilization of it in the national programs. The irrigated trials were conducted at Ibadan, upland trials at Ikenne and screening for acid upland soils at Onne. Yield nurseries had three replications in a randomized complete block design. The obser­ Table 9. Performance of tolerant rice entries in iron vational nurseries and initial evaluation trials were toxic soils in Bende valley, Nigeria, 1983 not replicated. Leaf dis- coloration Yield, t/ha Reac- International rice yield nursery, very early Entry scorea Bende IITA tionb duration (IRYN-VE). This nursery consisted of 29 ITA 238 ..... ... . ... ...... . 3.2 2.81 4.63 R entries from national breeding programs in India, ITA 239 .. . .. ... . ... .. . ... . 3.0 2.81 4.73 R Taiwan and Sri Lanka and from IRRI, with one ITA 242 ......... . . ........ 3.3 2.41 4.61 R international check, IR 50. The local check was ITA 244 ............. ...... 4.2 1.81 4.13 M FARO 26, a selection from IR 269-26-3-3-3. IR 25925-84- ITA 245 ... . . . .. ........... ·3.0 2.41 4.04 R 3-2 gave the highest yield, followed by IR 9752-71-3-2 ITA 247 ............ ........ 3.8 1.87 4.52 R (Table 10), which was among the best yielders in the ITA 250 ............... .... 3.3 1.47 4.43 R ITA 253 ... .. ..... . ........ 4.7 2.94 - c M 1981 and 1982 IRYN-VE trials in several Asian and ffi5 ................... . ... 4.7 3.08 4.22 M African countries. This entry has long translucent Suakoko 8 . . ......... ... ... 2.5 2.61 4.23 RR grains. Leaf and neck blast were moderately severe. Gissi 27 (resistant) ... . ... . .. 3.5 RR Some entries had reaction scores of7 to 9, but IR 9752- IR 26 (susceptible) ... . . ..... 6.0 0.13 3.54 S 71-3-2 proved resistant. Because of its short duration, LSD (5%) .................. 1.0 1.16 n.s. good grain quality and high yield potential, this entry aThese scores are based on IRRI's standard evaluation system for should be tested in irrigated double cropping systems rice. ~R = highly tolerant, R = tolerant, M = moderately in Africa. tolerant and S = susceptible to iron toxicity. eNo data. 10 Cereals Table 10. Performance ofselected entries in international rice yield nurseries, irrigated, IITA,1983 . Yield, Plant Growth dura- Lodging, Leaf Neck Variety kg/ha height, em tion, days 1-9 blast,0-9 blast, 0-9 Very early maturing ill 25925-84-3-2 ................... . .. .. . . .... . 4,160 109 99 1 0 o ill 9752-71-3-2 ............................... . 4,016 88 97 1 0 o BG367-4 .. .. ... ....... . ............ ........ . 3,891 129 105 5 0 o UPR 254-35-3-2 .............................. . 3,786 96 102 3 1 o ill 28128-45-2 ....... ....... ... . . ..... ... . ... . 3,736 108 98 5 0 o ill 28210-96-4-3-3 ...... ... ... .. .............. . 3,725 99 98 1 0 o UPR 103-80-1-2 .............................. . 3,691 95 97 1 3 3 IR 25924-51-2-3 .............................. . 3,565 104 100 1 0 o ill 29692-65-2·3 . .. .... ...... ... . . .. . . ..... ... . 3,546 109 102 1 0 o IR 25898-57-2·3 ...... .......... .......... . .. . . 3,510 104 99 1 0 o FARO 26 (local check) ....... . ..... ....... . . . . 3,183 138 120 5 0 o Mean... . . ......................... ........ 2,817 LSD (5%) .. . . . . .. . . .. .. .. .. .. . . . . . . . . .. . . . . . 882 C.V. , 0/0' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Early maturing BR 161-2B-59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,011 85 116 1 0 0 ill 36 (international check) . . . . . . . . . . . . . . . . . . . . 3,806 86 113 3 0 0 ill 21015-80-3-3-1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,718 106 114 1 0 0 C 1322-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,711 97 115 3 0 0 C 1321-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,705 93 114 3 0 0 ill 13540-56-3-2-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,416 117 120 1 3 5 FARO 27 (local check) ... ; . . . . . . . . . . . . . . . . . . . . 3,413 81 110 1 0 0 ill 13240-82-2-3-2-3-1 .. . . . . . . . . . . . . . . . . . . . . . . . . 3,279 85 114 1 0 0 KA1.12084 . .. ...... ... ......... . ... _ . . . . . . . . . 3,245 100 110 1 1 1 KAU 1727 .... _........ . .... .. . . ... .......... 3,239 97 114 1 1 0 Mean.. . ......................... ....... ... 2,296 LSD (5%) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 563 C.V., 0/0' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Medium duration ill 28118-138-2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,643 109 132 1 0 0 ITA 123 (local check) . . . . . . . . . . . . . . . . . . . . . . . . . 4,601 100 124 1 0 0 ITA212.... ..... ............. . ...... ... ..... 4,456 104 127 1 0 1 IR 42 (international check) . . . . . . . . . . . . . . . . . . . . 4,386 100 133 1 0 0 ill 19670-263·3-2-2-1. . . . . . . . . . . . . . .. . . . . . . . . . . . 4,145 107 127 3 0 0 BW 295-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,003 106 130 3 0 0 ill 9852-22-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,998 95 128 1 0 0 IR 27325-63-2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,937 107 132 1 0 0 RAU 2004-6-69-2-13. . . . . . . . . . . . . . . . . . . . . . . . . . . 3,919 89 124 1 0 1 BG 379-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,917 92 129 1 0 0 Mean.......................... . ........... 3,641 lli\:) \~o/o) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 605 C.V. • %...................... . .. .. .......... 10 International rice yield nursery, early du­ International rice yield nursery, medium du­ ration (IRYN-E). This nursery contained 28 entries ration (IRYN-M). The 29 entries in this nursery from national breeding programs in Bangladesh, were nominated by national breeding programs in India. the Philippines and Taiwan and from IRRI and Bangladesh, Brazil. Burma, India. Indonesia and Sri included an international check, IR 36. The local Lanka and by IIT A and illRI. The local check was ITA check was FARO 27. The highest yielder was BR 161- 123 (Table 10). ill 28118-138-2-3 gave the highest yield. 2B-59. followed by IR 36 and IR 21015-80-3-3-1-2 (Table followed closely by ITA 123, ITA 212, ill 42 and IR 10). The first two are dwarf varieties and the third 19670-263-3-2-2-1. IR 28118-138-2-3 and ill 19670-263-3- 'i>eID1dwart with growth duration of about 115 days. In 2-2-1 have long slender grains that are almost trans­ the 1982 illYN-E trials, ill 21015-80-3-3-1-2 was one of lucent. The latter was one of the top five yielders in the highest ranking entries. based on average yields the 1982 IRYN-M based on averages for 32 test for 38 locations in Asia, Africa and Latin America. ill locations in Asia, Africa and Latin America. Both 36 performed better than the local check. leaf and neck blast were minimal in this test. Cereals 11 WARDA coordinated varietal trial, irrigated, selections; most were semidwarf to "intermediate in moist zone, short duration. This trial consisted of plant height. At Ibadan the nursery was planted in 14 entries, with IR 36 as the local check. Leaf and neck two-row plots 5 m long and was not replicated. The blast were minimal, but some entries had glume local checks were BG 90-2, ITA 121 and ITA 123. Plant dis<:oloration scores of up to 5. The top yielder was IR height, maturity period, phenotypic acceptability, 21931-47-3-3, followed by ITA 245 and KN 144; all and field reaction to diseases were recorded. Leaf and these entries were significantly higher in yield than neck blast .. and glume discoloration were light to IR 36 (Table 11). KN 144 gave the highest yield in the moderate. The entries ' that received better pheno­ 1982 test at lITA and several other locations in West typic acceptability scores than the checks at ma­ Mrica but was moderately susceptible to leaf blast in turity were: C 1158-7, C 1252-9, ECIA 31-36-3-1, IR some locations. This variety also gave good results in 13525-43-2-3-1-3-2, IR 13538-48-2-3-2, IR 13539-100-2-2- WARDA on-farm trials, yielding 4 to 6 tjha. ITA 245 2-3, IR 25861-153-1, IR 25861-31-1-3, IR 25861-35-3-3, IR had the longest growth duration in this trial. 25861.64-3-2, IR 28126-45-3-3-2, M 57B-146-1,R 9-1-6-1-2- WARDA coordinated varietal trial, irrigated, 7-7 and IR 21015-80-3-3 .. 1-2. moist zone, medium duration. In this trial of 15 Irrigated initial evaluation trial. This trial entries, IR 2928-7-3-1-1 gave the highest yield, fol­ contained 193 entries, most of them semidwarf with lowed by ITA 212, IR 54 and IR 4422-98-3-6-1 (Table 11). early to medium growth duration. The nursery was Leaf and neck blast were minimal. BR 508-B2-910dged grown in three-row plots 5 m long and was fertilized badly. ITA 212 (BG 90-24jTetep) has produced yields with 120-90-90 kgjha of N, P 205 and K20. Pressure ranging from 4 to 7 tjha at several locations in from leaf and neck blast, leaf scald, brown spot and Nigeria and elsewhere in West Africa under both glume discoloration was generally light. A few ap­ irrigated and hydromorphic conditions. IR 54 and IR parently very susceptible entries were affected by . 4422-98-3-6-1 also gave high yields of 4 to 7 tjha in 1981 moderate to severe neck blast. Of the 23 entries and 1982 trials in West Africa. selected, the following seemed most promising: 32- Xuan, 5-P, BR 40-B2-1jC3, ITA 162, ITA 212, CP 4-Cl, International rice observational nursery (IRON 1983). This trial was composed of 350 entries Si pi C 92033, BW 267-3, IR 4422-98-3-6-1, B 541-PN-585- from IRRI, lITA and national programs in 16 coun­ 3-1, B 3981C-PN-146-2 and P 1486-707M. tries. There were very early, early, and medium WARDA coordinated varietal trial, upland, duration materials as well as a few late maturing moist zone, short duration. This trial was com- Table 11. Performance of selected rice varieties in a WARDA coordinated varietal trial, irrigated, moist zone, IITA,1983 Yield, Plant Growth dura­ Lodging, Glume discolora­ Variety kg/ha height, em tion, days 1 to 9 tion, 0 to 9 Short duration IR 21931-47-3-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,307 94 118 1 3 ITA245 .. . ... . . . .... . .. ... . . .. . . ..... . . . . . .. .. 4,917 97 135 1 3 KN 144. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,654 113 117 1 1 IR 1358-48-2-3-2. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 4,188 103 115 1 3 KAU 166 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,127 99 112 1 5 CNM 31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,049 96 117 1 1 C 1322-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,011 110 115 1 1 IR 36 (local check) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,272 87 102 1 1 Mean. ... . . . . . ... . .. . .. . . . ..... . ... . .... .. .... 3,888 LSD (5%). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 750 C.V., oinse, Upper Volta. At each location the varieties because of drought,w hich set in before they flowered. were evaluated in plots of four rows 4 m long, with UTA also distributes new cowpea breeding lines to a randomized block design with four replications. national programs through cowpea .international The varieties were of various colors, but most were trials (CIT), which are formed every year. These trials tan or red with smooth seed coats. include only lines that have been tested in pre- The yields of some varieties in this trial are listed in liminary and advanced trials at diverse locations Table 4. Their performance at all locations was within Nigeria (representing the forest zone, derived generally poor, although TVx 4654-44E performed savanna, Guinea savanna and Sudan savanna) and fairly consistently at all locations. TVx 1948-01F a lso have proved superior in disease and insect resistance, performed consistently in Nigeria but poorly at yield potential, seed quality and maturity. Often, Table 1. Performance of cowpea lines in initial evaluation trials at various locations in Nigeria, 1983 Grain yield, kg/ha UTA 100- First Second seed Seed Disease reactionb Line season season Mokwa Samaru Mean wt.,g type8 Anth. BBL BB WB Sept. IET-1 (1982) IT 82D·551-3 .... . ..... ... • .. 1,760 1,394 2,125 2,080 1,840 18 TIS S R R R R IT 82D·634·2 ......•...•... .. 1,905 1,035 2,125 1,446 1,632 12 W/S R R R R S IT 82D·559-1 ...... . , ........ 2,212 480 1,875 1,788 1,584 18 TIS MR S S R MR IT 82D·625-1 ................ 1,582 1,015 2,000 1,248 1,461 12 RIS R R S R R IT 82D-623·6 ............... . 1,885 1,008 1,000 1,872 1,441 17 W/S R S R R R IT 82D-544-4 .......... .. .... 1,887 361 2,125 1,456 1,407 20 WIWr R MR S R R IT 82D·544-2 ... .. ..... ...... 1,465 893 1,125 1,456 1,234 18 C/Sp R R MR R R IT 82D·550-4 ... .... .... ..... 2,020 1,259 875 936 1,272 17 TIS MR R R R R TVx 3236 (check) .... .... , ... 1,317 1,288 1,567 1,144 1,329 14 CIR R R R R S lET- 2 (1982) IT 82D·480-1 ... .............. 2,020 644 2,438 1,612 1,679 14 BIR S S R S IT 82D-476-3 ................ 1,700 1,177 1,750 1,872 1,625 16 BIR S R R MR IT 82D·480-2 .. .. . , .. .. . ... .. 2,348 693 1,688 1,560 1,572 16 BIR S MR R S IT 82D·479·1 ................ 1,373 1,144 1,500 2,080 1,524 15 BIR MR R R S IT 82D·484-5 .... .... ........ 1,735 992 2,000 1,248 1,493 14 BIR R S S S IT 82D·446-8 ...... . .. ... .. .. 1,300 1,273 1,438 1,560 1,393 21 BIR S S S MR IT 82D-450-4 ................ 1,055 1,052 1,875 1,560 1,385 14 BIR S S R R IT 82D-446-4 .... .... ........ 1,300 1,115 1,688 1,248 1,337 21 BIR S S R MR TVx 3236 (check) ....... . .... 1,712 1,056 1,524 1,404 1,424 14 CIR R R R S lET- 3 (1983) IT 82D-593-8 .. .... .... ...... 1,369 1,411 2,422 2,038 1,822 17 WIR R R R MR IT 82D-597-3 ................ 1,331 1,306 2,255 2,004 1,724 19 W/S R R R R IT 82D·595-2 ............. ... 1,602 1,289 1,921 1,878 1,673 18 WIR R R R MR IT 82D·596·8 ...... ..... ..... 1,525 1,423 1,879 1,837 1,669 19 WIR R R R S IT 82D·596-3 ................ 1,321 882 1,879 2,463 1,636 17 W/S R R R R IT 82D-582-5 .. ....... ....... 1,536 1,027 1,892 1,962 1,604 17 W/R R MR R R IT 82D-606-6 ........ .. • . . ... 1,902 952 1,670 1,837 1,590 21 WIR R R R R IT 82D-593-2 ...... ... ....... 1,055 1,723 2,004 1,419 1,550 16 WIR R R R MR TVx 3236 (check) .... .... .... 1,200 1,307 2,096 1,353 1,533 14 CIR R R R S lET- 4 (1983) IT 82D·495-2 ................ 1,503 1,880 1,879 1,503 1,691 18 B/S R R R R R IT 82D·519-4 .... .. .......... 967 1,667 2,117 1,503 1,563 22 WISp R MR R S R IT 82D-513-1 ................ 807 2,062 1,670 1,667 1,552 21 W/S R MR R S R IT 82D-506-4 ................ 1,650 1,356 1,879 1,294 1,545 18 W/S R S MR S R IT 82D-506-5 ................ 1,759 1,216 1,545 1,503 1,506 15 W/S S R R S S IT 82D·516-5 . ............... 705 1,612 2,046 1,587 1,488 19 WISp R MR MR MR R IT 82D-49Q.2 ........ . .. ..... 1,294 1,511 2,046 960 1,453 17 BIR R R R S MR IT 82D·513-5 ................ 1,166 1,612 1,336 1,503 1,404 19 WISp S R R R R TVx 3236 (check) .... ........ 1,403 1,660 1,912 1,236 1,552 14 CIR R R R R S IItf = tan, S = smooth, W = white. R = rough, Wr = wrinkled, C = cream, Sp = split and B = brown. . bAnth. = anthracnose, BBL = brown blotch, BB = bacterial blight, WE = web blight, Sept. = septaria, R = resistant, MR = moderately resistant and S = susceptible. 66 ( ,rain Legumes more than one cowpea international trial is formed so States.-B.B. Singh, B.R. Ntare, S.R. Singh and R.A. that varieties' with common characteristics can be Adelehe grouped. Three cowpea international trials were distributed Extra-Early Varieties in 1983: CIT-I, which contained 10 extra-early matur­ ing varieties; CIT-2, with 20 medium maturing va­ Good progress was made this year in developing rieties; and CIT-3, which was made up of 10 bruchid varieties that mature in 55 to 65 days and have resistant varieties. All three trials included a na­ various sizes and colors of seed to suit different tional check. Field books and a suggested field layout regional preferences. Disease and insect resistance are being incorporated into these materials through a for each trial were sent along with the seeds. A total of 212 sets were sent to 51 countries; 140 sets went to backc rossing program. Sixty new crosses were made Africa, 43 to Asia, 36 to Central and South America among the newly developed extra-early lines and and 2 to the United States. The results have just with lines having resistance to diseases and insects. begun to come in and will be reported in the 1984 IIT A Preliminary trials. Selected extra-early maturing Annual Report. advanced breeding lines were evaluated in two pre­ Many scientists have requested seeds of elite liminary trials. The lines in trial 1 mature within 62 to breeding lines for their breeding programs. A total of 69 days and those in trial 2 within 52 to 65 days. Each 91 requests for 2 to 10 varieties were received this year trial consisted of20 entries, plus TVx 3236 as a check from 33 countries, including the United Kingdom, representing medium maturing varieties. In trial 2 France, The Netherlands, Italy and the United one of the previously developed 60-day cowpeas, Table 2. Performance of cowpea lines in preliminary trials at locations in Nigeria, 1983 Grain yield. kg/ha IITA 100- First Second seed Seed Disease reaction b Line season season Mokwa Samaru Mean wt.,g type8 CYMV CAbMV Anth. BBL BB Sept. Preliminary trial 3 IT 82D-927 ......... 1.599 1.931 1.284 1.605 13 B/S R R R RMR S IT 82D-702 ......... 1.363 2.286 1.138 1.595 16 W/R R MR R R R S IT82D-849 ......•.. 1.146 2.296 1.294 1,579 15 W/R R S R R R S IT 82D-704 ...... . .. 1.340 1.722 1.503 1.522 21 W/R R S R R R S IT 82D-663 .. ....•.. 1.059 1.900 1.576 1.512 17 W /R R S R R R S IT 82D-713 ...... • .. 1.271 1.962 1.253 1.495 16 C/R MR MR R R R S IT 82D-950 ......... 1.238 1.774 1.378 1.480 17 CIS R MR R R S MR IT 82D-703 ..... . .. . 1.215 1.879 1.273 1.456 22 C/R MR R R MR R S IT82D-716 ......... 1.404 1.670 1.148 1.407 16 C/R MR R R R R S IT 82D-952 ......... 1.479 1.336 1.378 1.398 12 W/R R S R RMR S TVx 3236 (check) ... 1.402 1.994 1.169 1.522 12 C/R S S R R R S LSD (5%) .......... 322 346 253 C.V .•% ............ 18 15 14 Preliminary trial 4 IT 82D-768 ......... 1.682 1,374 2.046 1.058 1.540 18 TIS R S R MR R S IT 82D-847 ......... 1.655 1.203 1.816 1.430 1.526 13 TIS MR MR R R R R IT82D-829 ......... 1.767 1.376 1.639 1.159 1.485 14 TIS R R R R R R IT82D-831 ......... 2.041 1.268 1.587 1.033 1.482 14 TIS R R R R R R IT 82D-768 ......... 1.719 1.301 1.524 1.384 1.482 14 TIS R R R MR R MR IT 82D-807 ......... 1.840 1.209 1.670 1.075 1.449 11 TIS MR R R R R R IT 82D-844 ......... 1.485 772 2.067 1.447 1.442 15 TIS R R S R R MR IT 82D-859 ......... 1.475 1.070 1.722 1.326 1.398 19 TIS R R R MR R R IT82D-345 ......... 1.420 825 1.889 1.367 1.375 15 TIS R R S R R MR IT 82D-744 ......... 1.446 1.003 1.399 1.054 1.226 14 TIS R R R R R R IT 82D-752 ......... 1.741 954 1.639 1.002 1.334 15 TIS R R R R R R Check varieties: TVx 1948-01F .... 1.914 944 1.827 946 1.408 13 TIS R R R R R R TVx3236 ........ 1.912 1.308 1.952 595 1.442 12 C/R S S R R R S LSD (5%) .......... 344 245 436 289 C.V .• % ............ 18 16 18 19 IS = brown. S = smooth, W = . white, R = rough, C = cream and T = tan. bCYMV = cowpea yellow mosaic virus, CAbMV = cowpea aphid borne mosaic virus, Anth. = anthracnose, BBL = brown blotch, BB = bacterial blight, Sept. = Septoria, R = resistant, MR = moderately"resistant and S = suscept.ihle. Grain Legumes 67 Table 3. Performance of cowpea lines in advanced trials at locations in Nigeria, 1983 Grain yield. kg/ha UTA 100- First Second seed Seed Disease reactionS Line season season Mokwa Samaru Mean wt.,g typea CYMV CabMV Anth. BBL BB WB Sept. Advanced trial 1 IT 81D-1137 ........ 1.574 1.477 2.244 1.785 1.770 23 W /S R R R R R R IT82D·709 ......... 1.482 1.324 2.077 1.764 1.662 16 C/R MR MR R R R S IT 81D·1063 ........ 1.198 1.152 2.255 1.697 1.575 21 RIS S R R R R S IT 81D-I039 ........ 1.172 942 2.119 1.587 1.455 21 RIS S R R SMR MR IT 81D·1054 ........ 1.198 931 1.816 1.774 1.430 21 RIS S R R S R S IT 81D·1186-69 ...... 1.430 893 1.944 1.326 1.411 16 CIS S R R R IT 81D-1065 ........ 1.384 735 1.878 1.628 1.407 24 RIS R R R SMR S IT 81D·I061 . . ...... 1.226 663 1.701 1.749 1.335 25 RIS MR R R SMR R Check varieties: TVx 1948-01F .... 1.991 1.179 2,129 1.837 1.789 13 TIS R R R R R R TVx3236 .. ...... 1.516 1.184 1.900 1.035 1.409 12 C S S R R R S LSD (5%) .......... 549 289 393 402 C.V. • % ............ 33 22 16 20 Advanced trial 2 IT 82D·975 . ..... ... 1.454 2.484 1.827 1.921 17 B/R R S R R S TVx 3536-6-1 ....... 1.376 2.296 1.900 1.857 14 B R R R R S IT 81D·1137 ........ 1.322 2.317 1.754 1.798 25 W /S R RMR R S IT 81D·1189-8l. ... .. 1.323 2.150 1.910 1.794 15 W/R R RMR R R IT 81D·1206·179 ..... 1.222 1.931 1.983 1.712 14 W/R R R R R R IT 81D-981 ......... 1.166 2.056 1.691 1.638 15 B/S S R R R R IT 81D-898 ... ...... 989 2.108 1.764 1.620 22 W/R MR R R R S IT 82D·716 ......... 1.083 2.171 1.555 1.603 15 C/R R R R R S IT 81D·897 ......... 1.010 1.847 1.889 1.582 22 W/R MR R R R S Check varieties: TVx3236 ........ 1.325 2.286 1.555 1.722 13 C/R R R R R S TVx 4659·03E .... 617 1.513 1.785 1.305 21 C R R R R R LSD (5%) .......... 253 408 443 C.V .• % ...... ...... 16 14 19 .. w = white, S = smooth, C = cream, R = rough, T = tan and B = brown. bCYMV = cowpea yellow mosaic virus, CAbMV = cowpea aphid borne mosaic virus, Anth. = anthracnose, BBL = brown blotch. BB = bacterial blight, WB = web blight, Sept. = septaria, R = resistant, MR = moderately resistant and S = susceptible. Table 4. Grain yield of medium maturing varieties in an international cowpea trial, 1983 UTA First Second Mokwa, Samaru, Kamboinse, Variety season season Nigeria Nigeria Upper Volta Mean kglha TVx 4654·44E ......... • ...• ' . .•... ........ 1.157 1.031 1.440 1.612 1.127 1.273 TVx 1948-01F ........ .•. .... . . .. .•....... 1.061 1.015 1.377 1.001 835 1.058 TV x 4659-02E ... ..... .•..••. ...... ...•... 1.264 700 1.503 858 846 1.034 TV x 4677-88E ....... .. .. . .•.. . •.. . . .. .. .. 809 820 1.210 1.287 953 1.016 TVx4661·07E ....... .. .. . .... ..... . .. . . .. 932 954 1.231 1.248 896 1.012 TVx 4677-010E .....•.. . ... •. ..•...... .... 1.158 735 1.169 1.118 880 1.012 TVx3236 ..........•.. . ... . . ..•.. . •.. . ... 1.095 786 1.232 884 994 998 IT8ID·1069 .......... ............ .... .... 1.104 879 1.221 611 946 952 Local check" . ................ . ......... . 653 846 0 0 839 0 Overall mean .. .... ...... ..... ......... .. 934 788 112 837 868 907 LSD (5%) ..... ....... ... ....... ....... .. 347 275 273 481 197 C.V. • % .................... .. . .. ......... 26 25 17 40 16 -Because the local varieties were late maturing, they were damaged by drought. 68 Grain Legumes IT 82E·60. was also included as a check. The lines in resistance to all the major diseases. Its yield can be trial 1 had medium to large seed of different colors. further increased by- raising plant population. Those in trial 2 were mainly small to medium and red These two trials were also conducted at Onne in with smooth testae. Both trials were conducted at southern Nigeria. They were planted in rice fallows IITA. Mokwa and Samaru in a randomized block during late October. as the rains began tapering off. design with four replications in plots offour rows 4 m and were ready for harvest by December. They rna· long. with spacing of 50 em between rows and 20 em tured in 54 to 64 days. while TYx 3236 required 74 within rows and two plants per hilL days. Although both trials suffered badly from cal· The performance ofthe best lines is shown in Table cium deficiency. the general yield level in trial 1 5. The most promising line in trial 1 was IT 82D· 789. appeared normal and was fairly encouraging. The which gave superior yields at all locations and highest yielding line was IT 82D· 784. with a mean of showed resistance to all the major diseases. It rna· 1.381 kg/ha. followed by IT 82D·655 (1.297 kg/hal and tured in 60 days. compared to 75 days to 84 days for IT 82D·640 (1.256 kg/hal. compared to 846 kg/ha for TYx 3236. In trial 2 the best line was IT 82D·885. which TYx 3236. The effects of calcium deficiency were more has large. red seeds and multiple disease resistance. pronounced in trial 2. where yield was drastically IT 82D·889 was the earliest of all the lines. requiring reduced. IT 82D·885 yielded about 833 kg/ha. com· only 52 to 55 days to reach maturity. compared to 60 to pared to 458 kg/ha for TYx 3236. 65 days for other lines and 75 to 80 days for TY x 3236. These data indicate that with proper management IT 82D·889 has red seeds. determinate plant type and it is possible to obtain a yield of 1 to 1.5 t/ha from Table 5. Performance of extra-early maturing cowpeas in preliminary trials at locations in Nigeria, 1983 Grain yield. kg/ha UTA 100· First Second seed Seed Disease reactionb Variety season season Mokwa Samaru Mean wt.,g type8 CYMV CAbMV Anth. BBL BB WB Sept. Preliminary triall IT 82D·789 .. . . ..... 2.054 1.597 1.266 1.366 1.576 17 T/S R R R R R MR IT 82D·812 ......... 1.924 1.180 1.609 1.346 1.515 13 TIS R R R S S R IT 82D·784 .... . .... 1.603 1.613 1.375 1.305 1.474 16 T/S R R R MR R R IT 82D·787 .... . .... 1.514 1.552 1.250 1.357 1.418 15 T/S R R R S R R IT 82D·640 . .... .... 1.740 1.304 1.641 939 1.406 20 W/R S S R R R S IT 82D·755 ......... 1.643 1.472 1.344 1.012 1.366 11 TIS R R MR R R R IT 82D·849 ......... 1.510 1.366 1.297 1.253 1.354 20 T/S R R R MRMR R IT 82D·641. ... .. . .. 1.775 1.100 1.469 960 1.326 20 W/R R S R MR R MR IT 82D·638 ......... 1.531 1.409 1.156 1.169 1.316 13 W/R R S R R R R IT 82D·720 ......... 1.702 1.183 1.344 898 1.282 14 CS R R R R IT 82D·948 ......... 1.912 1.134 1.172 768 1.247 17 TP/S R R R R R MR TVx 3236 (check) . .. 1.393 1.441 1.844 616 1.323 S S R R R S LSD (5%) . . ........ 474 297 370 336 C.V .. % ... . ........ 22 16 20 24 Preliminary trial 2 IT 82D·885 .. .... .. . 1.550 1.228 1.641 1.639 1.517 16 Rd/S MR MR R R R R R IT 82D·874 . ... .. . .. 1.488 1.108 1.516 1.451 1.391 12 Rd/S R R R R R R R IT 82D·667 .... . .... 1.262 1.132 1.668 1.294 1.344 15 Rd/S R R R MR R R R IT 82D·881. ...... . . 1.426 1.099 1.467 1.263 1.314 14 Rd /S MR MR R MR RMR R IT 82D·860 ... . . . .. . 1.620 1.106 1.281 1.200 1.302 12 Rd/S R S R R R MR R IT 82D·872 .... . .... 1.228 1.300 1.453 1.217 1.299 10 Rd/S R R R R R R R IT82D·888 . ... . . .. . 1.442 1.084 1.438 1.211 1.294 14 Rd/S R R R MR R R R IT 82D·871. ... . . ... 1.233 1.136 1.563 1.211 1.285 11 Rd/S R R R R RMR R IT 82D·875 .... . ... . 1.399 1.094 1.203 1.305 1.250 12 Rd/S R R R R R R R IT 82D·892 .... . . . .. 1.382 950 1.281 1.294 1.227 12 Rd/S R R R R R R R IT 82D·889 ... ... . .. 1.172 650 1.422 1.221 1.116 12 Rd/S R R R RMR R MR Check varieties: TVx3236 .... .. .. 1.184 1.328 1.938 835 1.321 13 C S S R RMR S S IT 82E·60 ...... . . 1.533 886 1.281 636 1.084 18 W S R R S R S S LSD (5%) ..... ... .. 545 319 403 264 C.V .• % ....... ... .. 29 22 20 16 a.r = tan, S = smooth, W = white, R = rough, P = purple, Rd = red and C = cream. . bCYMV = cowpea yellow mosaic virus, CAbMV = cowpea aphid borne mosaic virus. Anth. = anthracnose, BBL = brown blotch, BB = bacterial blight, WB = web blight, Sept. = septoria, R = resistant, MR = moderately resistant and S = susceptible. Grain Legumes 69 Table 6. Grain yield of extra-early maturing cowpea varieties in an international trial, 1983 UTA First Second Mokwa, Samaru, Kamboinse, Seed Variety season season Nigeria Nigeria Upper Volta Mean type8 kg/ha IT 82E-16 ....... _ .. . _. .. _ ...... 1,473 1,498 1,828 1,339 1,001 1,428 R/S IT 82E-18 .......... .. .......... 1,452 1,480 1,843 1,352 847 1,395 R/S IT 82E-13 ...... .... ........... . 1,616 943 1,297 1,179 1,079 1,221 R/S IT 82E-32 ........... ... ........ 1,239 1,075 1,547 1,040 1,033 1,187 R/S IT 82E-56 ........ . ....... _ . .... 870 1,120 1,250 1,728 840 1,221 W IT82E-9 ................. . . . .. 1,373 899 1,328 793 739 1,026 ~/S IT 82E-41. .... _ ........ . .... _ .. 1,138 1,101 1,188 788 655 976 W/R IT 82E·77. ........ •. . .. . . . . . ... 826 1,127 1,141 819 673 917 W/R IT 82E-60 ...................... 820 1,154 1,171 754 882 912 W/R Local check ................... 1,183 1,381 1,887 656 Overall mean . ................. 1,199 1,178 1,428 998 803 1.121 I.BD (5%) ..................... 489 520 294 372 202 C.V.,% ....................... 28 30 14 26 17 IRIS = red smooth, W/R = white rough and BIS = black smooth. extra-early cowpeas grown in rice fallows. At present cowpea varieties were evaluated for green pod and no cowpeas are grown in the area, and people con· seed yield at three locations, IITA, Mokwa and sume mostly starchy foods. Popularization of cowpea Samaru. Because harvesting of green pods at Samaru cultivars could add considerably to the farmers' was delayed, the data were excluded from the analy· income and improve people's diets. sis. At each location the varieties were planted in a International trials. For the first time, a trial randomized complete block design with six repli· consisting of nine extra-early maturing varieties was cations. The first three replications were harvested sent to more than 50 countries around the world. The for green pods and the last three for seed. The entries in this trial were the most promising varieties performance of the varieties is shown in Table 7. In selected from two extra·early maturing variety trials the first season at IITA, the yields of the bush types conducted in 1982. The yields of these varieties in ranged from 8 to 15 tfha of green pods, compared to 9 Nigeria and Upper Volta are listed in Table 6. At IITA to 10 tfha for the climbing types. Some of the bush and Mokwa, the local check was Ife Brown; at types also produced grain yields of over 1.3 tfha. At Samaru the local check germinated poorly and was IITA during the second season and at Mokwa, the therefore excluded from. the analysis. All the extra· yield of fresh pods was relatively low, owing to early lines matured within 58 to 65 days; Ife Brown drought, which permitted only one picking compared required an average of 75 days to mature. Except for to four pickings at IITA in the first season. The yield the white·seeded varieties, which are susceptible to of IT 81D·1228·14, averaged for the two locations, brown blotch, all the varieties had a moderate to high exceeded that of the local checks. IT 81D·1228-16, level of resistance to several diseases. The red-seeded IT 82D·1228-10 and IT 8ID·1228·13 gave the highest varieties yielded as well or even better than Ife grain yields, showing some promise as dual-purpose Brown.- B.B. Singh, B.R. Ntare and S.A. Shoyinka varieties.- B.R. Ntare and B.B. Singh Vegetable Cowpeas Insect Resistance One of the cowpea program's aims is to develop bush Considerable progress was made in developing hy· type vegetable cowpeas that have high yield potential brid populations and advanced breeding lines with and resistance to major diseases. This year several F good agronomic characteristics and individual as 3 and F 4 progenies were evaluated for plant type and well as combined resistance to aphids, bruchids and screened for resistance to several diseases, and thrips. In addition, genetic studies were conducted to selected progenies were further evaluated in the F elucidate the nature of inheritance of resistance to 5 generation. The F. progenies have been bulked and aphids and thrips. Efforts were also made to identify will be evaluated in preliminary yield trials in 1984. sources of resistance to Maruca testulalis and pod Further crosses were made between vegetable types bugs. and grain types to develop a more erect type of Bruchids. Breeding for bruchid resistance re­ vegetable cowpea and incorporate disease and insect ceived much attention this year. Twenty·eight new resistance into it. We will also select for vegetable crosses were made involving bruchid resistant types that are outstanding in production of green parents, and the segregating populations were eva· pods as well as grain. luated for disease resistance and agronomic charac­ Eight bush type and two climbing type vegetable teristics as well as for bruchid resistance. Twenty· 70 Grain Legumes four new advanced breeding lines with bruchid and their reaction to various diseases is shown in resistance and good agronomic characteristics were Table 8. The most promising among these lines were evaluated for seed quality. The yield of these lines IT 82D·54H, 82D·516·5, 82D·524·3, 82D·703 and Table 7. Yield of vegetable cowpeas at locations in Nigeria, 1983 IITA, first season UTA, second season Mokwa Mean Plant Green Dry Green Dry Green Dry Green Dry Variety type pods seed pods seed pods seed pods seed kg/ha IT 8lD·1228-14 ..... .... .. bush 15,131 1,247 6,419 1,095 9,102 797 10,217 886 IT 8lD·1228-10 ..... • ...•. bush 14,257 836 4,152 1,186 10,758 1,315 9,722 1,102 IT 8lD·1228·15 ..... . ...•. bush 15,285 1,030 3,917 1,186 9,658 837 9,620 913 IT 8lD·1228-12 ........... bush 11,864 1,165 6,166 1,145 8,935 999 8,988 998 IT8lD·1228-16 ........... bush 13,510 1,456 3,537 1,136 8,921 1,315 8,656 1,342 IT 8lD·1228-13 ......•.... bush 14,799 1,129 4,461 858 6,307 1,408 8,522 1,144 TVx 3442·27E ..... .... ... climbing 10,151 904 3,979 1,096 10,479 793 8,203 994 TVx 5881·016F ..... . . . ... bush 8,709 777 3,972 988 6,597 696 6,426 962 Local checks : Bush-Sitao . ........... bush 6,466 446 1,984 833 8,544 1,495 5,885 1,048 FARVE·13 ............ climbing 8,725 585 4,113 574 8,530 951 7,123 750 Overall mean ............ 11,890 957 4,264 1,009 8,783 1,088 8,312 1,018 LSD (5%) ............... 4,181 362 1,392 363 2,803 461 C.V.,% ................. 21 22 19 21 19 25 Table 8. Performance ofbruchid resistant lines in initial evaluation trials at locations in Nigeria, 1983 Grain yield, kg/h. IITA Reaction to:a First Second Anthrac· Brown Bacterial Line season season Mokwa Samara Mean Bruchids nose blotch blight Septoria IET-1 IT 82D·544-4 ....... 1,887 361 2,125 1,456 1,407 R R MR S R IT 82D·542·2 .. . .... 1,305 481 1,500 568 938 R R R MR R TVx 3236 .......... 1,317 1,288 1,567 1,144 1,329 S R R R S IET-2 IT 82D·448-4 ....... 1,300 1,115 1,687 1,248 1,338 R S S R R IT 82D·448-2 ....... 1,220 868 1,625 1,456 1,292 R S S R MR IT 82D·453·2 ... .... 1,520 768 1,437 1,404 1,282 R R R S MR IT 82D·456-4 ....... 1,287 901 1,125 1,040 1,089 R S S S R IT 82D·475·5 ....... 1,340 862 625 1,248 1,018 R S MR S MR TVx3236 .......... 1,712 1,056 1,524- 1,404 1,424 S R R R S lET-3 IT 82D·600-5 ....... 552 754 875 1,820 1,008 R R R R MR TVx3236 . .. . ...... 1,200 1,307 2,096 1,353 1,533 S R R R S IET-4 IT 82D·508-5 . . .. . .. 1,759 1,216 1,545 1,503 1,506 R S R R S IT 82D·516·5 .. . .... 705 1,612 2,046 1,587 1,487 R R MR MR R IT 82D·504-4 ....... 1,642 1,249 1,503 1,169 1,391 R R R R MR IT 82D·486-6 ....... 1,490 1,169 1,336 1,336 1,333 R S R R MR IT 82D·527·5 ....... 1,241 1,189 1,378 1,503 1,328 R S MR R R IT 82D-486-4 . ...... 1,526 805 1,837 1,086 1,314 R S MR R MR IT 82D·524-3 ....... 1,002 1,657 1,253 1,336 1,312 R R R R R IT 82D·486-7 . ..... . 822 1,249 1,278 1,336 1,196 R S R R MR TVx 3236 . ........ . 1,403 1,660 1,912 1,236 1,552 S R R R S Preliminary trial 3 IT 82D·703 ......... 1,215 1,879 1,273 1,456 R R R R S IT 82D·716 ......... 1,404 1,670 1,148 1,407 R R R R S TVx3236 ........ . . 1,402 1,994 1,169 1,522 S R R R S LSD (5%) ......... 322 346 353 ItR = resistant. MR = moderately resistant and S = susceptible. Grain Legumes 71 82D·716, all of which showed very high yield poten· the resistant lines, including TVu 2027, had 15 to 40 tial, bruchid resistance and multiple disease resist· exit holes per 100 seeds and 20 to 30% of the seeds ance. IT 82D· 716 also has resistance to thrips. These were damaged, compared to 240 exit holes per 100 lines will be further evaluated in the coming year. seeds and 94% damaged seeds for Ife Brown. The data Nine bruchid resistant lines selected from multi· clearly indicate that the resistant lines suffer only locational trials in 1982 were included in an inter· insignificant damage for up to three to six months of national trial that was sent to over 50 countries. This storage, w.hereas during the same period, the suscep· trial was conducted at three locations in Nigeria and tible line, Ife Brown, suffers 100% damage and be· at Loumbila, Upper Volta, by IITA staff. As shown in comes completely unfit for human consumption. The Table 9, the yield of all these lines was generally quite infestation level of this experiment was quite high good at IITA in the first season, at Mokwa and at compared to that prevailing under actual storage Loumbila. But because of drought, yields were low at conditions. With less insect pressure, the resistant Samaru and in the second season at IITA. Overall, lines may store well for up to nine months. The IT 8ID·985, 8ID·1064, 8ID·1137, 8ID·1007 and resistance of these lines is good enough to offer 81D·1032 appeared most promising. Of those lines substantial protection during storage.-B.B. Singh. IT 8ID·985 and 8ID·1137 are white seeded, and S.R. Singh and B.R. Ntare IT 8ID·1007, 8ID·1032 and 8ID·1064 are red seeded. All of these lines are resistant to most major diseases. Aphids. Considerable progress was made in gen· The results from other locations have started coming erating new populations from aphid·resistant and in and will be presented in the 1984 IITA Annual multiple disease· resistant parents, and the advanced Report. populations generated last year were screened for The resistance to bruchids of all nine lines evalu· aphid resistance in the greenhouse. A total of 201 ated in the international trial was tested against that breeding lines have been developed that combine of the original parent, TVu 2027, and a susceptible aphid resistance with good plant type and disease check, Ife Brown. Two·hundred·gram samples of all resistance. These will be further evaluated for agro· the lines were placed in three 500·ml jars with per· nomic characteristics, seed quality and disease reo forated screw caps. Two pairs of freshly emerged sistance. The most promising ones will be evaluated bruchids were placed in each jar and incubated in the in preliminary yield trials next year. bruchid bioassay laboratory. A random sample of 100 Genetic studies were conducted on the inheritance seeds was taken at various intervals during storage, of aphid resistance. An attempt was also made to beginning 33 days after infestation. The number of ascertain whether the genes for resistance in variou.s exit holes per 100 seeds, percentage of damaged seeds resistant lines are the same or not. The F ,. F 2' F 3 and and 100·seed weight were recorded. The experiment backcross populations. involving several resistant x continued for about nine months. susceptible as well as resistant x resistant parents All the new resistant lines had significantly fewer were screened under artificial aphid infestation. and exit holes, fewer damaged seeds and less of are· data on genetic segregation were collected. The three duction in 100·seed weight than Ife Brown and were sources of resistance were TVu 36. 801 and 3000. and just as resistant as the original parent, TVu 2027. the susceptible parents were IT 82E·16. IT 82E·60 and There were no significant differences among the TV x 3236. The data indicate that aphid resistance is a monogenically controlled dominant trait. This was resistant lines, including TVu 2027, in any of the parameters measured. At 90 days after infestation, true for all crosses, irrespective ofthe source of aphid resistance. These results agree with those reported in Table 9. Grain yield ofbruchid resistant lines in international trial a, 1983 IITA First Second Mokwa, Samaru, Loumbila, Variety season season Nigeria Nigeria Upper Volta Mean kg/ha IT 81D·I064 ... . ...•. .. . .. ....•...• ... . . ... 1.827 645 2,312 532 2,217 1,507 IT 81D·985 ........•.. .•. .... . •...... .. .... 1,475 834 1,797 1.248 2.557 1.582 IT 81D·1I37 .............. . .......... . ..... 1,798 825 1.687 858 1.821 1,398 IT 81D·I007 . .. .. ... . .. . . ... .. . ... ......... 1,535 1,037 1,844 624 1.980 1.380 IT81D·1032 .......................... . . ... 1.166 913 2.359 481 1,861 1,356 IT 81D·I020 ..................... . ......... 1,376 511 2,156 390 1.977 1,282 IT 81D·966 ........ . ...... • ... • ...•........ 625 610 1.813 1,ll27 2.197 1,254 IT 81D·1I57 .................. . ............ 1.204 715 1,843 247 1.985 1,159 IT 91D·994 ................................ 815 558 1,157 780 2.301 1.122 Local check ....... . .. . .................. . - 767 1,906 1,547 1,407 Overall mean ..... . ... . .... . . . ... . . . ...... 1.313 742 1.887 649 900 LSD (5%) ........... .. ................... 427 261 451 327 180 C.V .•% ............ . ......•... .. .......... 22 24 16 35 14 '/2 Crain Legumes Table 10. Segregation patterns for aphid resistance in which would have been numerous had plants been cowpeas, UTA, 1983 rated individually. The results indicated that re­ Number of plants sistance to thrips is a recessive trait controlled by Population Resistant Susceptible X' two recessive gene pairs.-S.R. Singh, B.B. Singh, IT82E·60 .......... . 19 A.B. Salifu, B.R. Ntare and D. Bata. TVu3000 .......... . 20 Maruca and pod bugs. To identify new and better Fl················ 40 sources of resistance to the pod borer (Maruca tes­ F, ............... . 188 67 0.22(3:1) F, X TVu3000 ...... . 54 tulalis) and pod sucking bugs, 7,400 cowpea germ· F, plasm lines were screened under field conditions at X IT 82E-60 ...... . 25 29 0.29(1 :1) Mokwa, where insect pressure is usually very high. Each germplasm line was planted in single·row plots the 1982 !ITA Annual Report. The data for one of the 3 m long and 75 em apart. The crop was sprayed once crosses, given in Table 10, clearly indicate single­ with Nuvacron (which kills thrips but has no effect on _gene inheritance. maruca) about four weeks after planting to avoid All the crosses involving resistant X resistant confusing the two types of insect damage. Since the parents gave only resistant progenies. No segre­ spraying brought about good flowering in most ofthe gation was observed in the F" F 2' F 3 or backcross lines, their subsequent performance depended pri· populations. Of the more than 1,000 F, plants marily on the level of infestation by maruca and screened, all were resistant. These data indicate that coreid bugs. aphid resistance in TVu 36, 801 and 3000 is controlled Alllines were examined 55 days after planting for either by the same gene or very closely linked genes. pod setting and damage caused by maruca and pod This study will be continued using other sources of sucking bugs. The pressure of both insects was so resistance and larger F 2 populations.-B.B. Singh, high that only 23 lines showed minimum damage. The S.R. Singh, B.R. Ntare and D. Bata most promising of these, by far, were TVu 1, 4, 1832, 1892, 1633, 4537, 9062 and 10284. TVu 946 was also Thrips. A total of 1,600 germplasm lines were screened for resistance 1.0' thrips in a screening block found to be moderately resistant to maruca, confirm­ bordered with pigeon peas, which harbor thrips and ing the findings of an earlier screening. But some of the other lines listed above appeared to be as good or ensure uniform infestation of the test materials. Spreader rows were also planted every five rows two better than TVu 946 in pod damage and seed quality. Seeds of these lines are being multiplied, and the lines weeks before planting of the germplasm lines. At initiation of flower buds, the spreader rows were will be evaluated again in replicated multirow plots uprooted and shaken to spread the thrips on test at !ITA and Mokwa.-B.B. Singh, L.E.N. Jackai, rows. This and the pigeon pea borders resulted in Q. Ng and B.R. Ntare very heavy thrips infestation. The test lines were examined for thrips damage three times during the Disease Resistance crop season. According to visual damage ratings Fungal and bacterial diseases. Good progress made over the season, a few lines appeared moder­ was made in developing breeding lines with reo ately resistant to thrips, but none were superior to sistance to several fungal and bacterial diseases. TVu 1509 or TVx 3236. Screening for resistance to forest zone diseases, such A trial consisting of20 advanced breeding lines, in­ cluding two e;>ne by two methods, visual counts and drop cloth counts, to determine which is the more precise. 50 r- IITA r- MOKWA At Mokwa popUlations of pod sucking bugs peaked at 53 bugs per 2 m of row in late October (Fig. 2) 40 - rf r- and averaged about 20 bugs per 2 m of row during the season. The population consisted mainly of 30 rfJ Clavigralla tomentosicollis, which accounted for over " ~ 70% of the total (Table 18). Not surprisingly, the 20 - ~ infestation reduced yield by over 80% (Table 17). ~ ~ - At IITA the population was generally low, with _ rf'. + 10 - peaks not exceeding 9 bugs per 2 m of row during the first season and 11 bugs per 2 m of row during the second (Figs. 3 and 4). The highest peaks occurred o r- -'e~te~~.!€t:: ~Q~ §2§2eg in mid·July and early November during the first Q~!.:NN~- ~ ~Ol P:::~::l'i2 and second seasons, respectively. Yield losses were (\j (\j I-- Season I -----I I--Seoson 2--1 Sampling c;lote higher in the first season (47%) than in the second Figure 1. Trends in the population of Maruca testulalis at (23.3%). Crop performance was generally poor in the locations in Nigeria, 1983. second season because of drought. Grain Legumes 77 A marked deviation from the pattern of previous Table 18. Population composition of pod sucking bugs years was the high population of Nezara viridula on on cowpeas, Mokwa, Nigeria, 1983 cowpeas (Table 19), which was exceeded only by that Species Drop cloth Visual count Of C. shadabi, the predominant species in the first percent season (except when sampling is done by visual . Clavigralla tomentosicollis ... . . 72.7 77.9 counts). Normally, the second season population C.shadabi ............. ..... . o o consists mostly of C. tomentosicollis at IITA, as at Riptortus dentipes .... , ...... . 4.0 3.1 Mokwa. This year, for reasons not yet determined, Aspauiasp . ................. . 3.4 3.3 N. viridula was predominant (43.8%), followed by Nezara uiridula .......... . . . . 12.4 10.6 C. shadabi (23.2%) and C. tomentosicollis (14.1%), Anoplocnemis curuipes ..... . . . 7.3 3.6 as determined by drop cloth sampling. Piezodorus guildini . .. ,'. ..... . 0.2 1.4 Two commonly used sampling methods are com· Relative variation8 .......... . 15.3 18.2 pared in Tables 18 and 19. The index of precision is the aSee definition of relative variation (RV) in accompanying text. relative variation (RV), which is the ratio of the standard error ofthe mean expressed as a percentage of the mean. The smaller the RV value, the greater the Number of bugs per 2m of row precision. For this kind of survey, anRV value of25% 60,----------------------------, is considered adequate. Judging from its lower RV values, drop cloth sampling appears to have been more precise at all locations. 50 At Mokwa, where the populations of pod sucking bugs were high , drop cloth and visual counts gave 40 identical results. But at Ibadan there were discrepan­ cies between the methods in estimates of population composition. For example, in the first season, 30 Riptortus dentipes was the most abundant species, Drop cloth followed by N. viridula and C. shadabi, according to visual estimates (Table 19). In the second season, 20 more C. tomentosicollis were counted with the visual method than with the drop cloth method. Strong fliers such as Riptortus sp. and 10 Anoplocnemis sp. are not usually collected in drop .......... Visual counts cloth samples (Table 19). As a result, this method, o L-....,-==L:-::!re':-=:.!IoI~L-J.-""-"'O:'-==""'-.....- --' despite its high precision, grossly underestimates 5 8 12 15 19 22 26 29 2 5 9 12 16 populations of these bugs. For the strong fliers, drop f----- Oct. I Nov.----l cloth sampling should be supplemented with visual Sampling date counts.-L.E.N. Jackai · Figure 2. Fluctuations in the population of pod sucking bugs on cowpeas, Mokwa. Nigeria, 1983. Flower thrips. Appropriate methods of determin· ing insect populations are essential to the develop­ ment of resistant crop varieties. The usual method of Number of bugs per 2m of row estimating thrips population has been to collect 10,-----------------------------, racemes, flowers or both in vials containing 30 to 50% alcohol. But this method removes a substantial part of the reproductive structures, possibly disrupting 8 the normal growth of the plants. For this and other reasons, evaluations were begun of other methods for 6 sampling thrips on cowpeas. , , # ,, Five methods were evaluated: water traps, sticky • ,, traps, the sweep net, collection of racemes or flowers 4 I , in alcohol and plant.shake boards. The study was carried out in aO.1-ha field planted to VITA-7 cowpeas ,~ and bordered on two sides by pigeon peas to build up 2 ~~ thrips infestation. Spacing between rows was 0.75 m ~. . and the distance between plants within rows 0.20 m. Sampling was begun 39 days after planting and was O~~~~~~~~_L_L_L~_L_L~ continued at five-day intervals for three weeks. 18 21 24 28 4 8 12 15 19 22 26 29 2 6 Water traps were made from white, rectangular I---June --+----- July I Aug . .., laboratory pans with a surface area of about 522 cm2 • Sampling date Ten pans were filled with clean tap water to 2 cm Figure 3. Fluctuations in the population of pod sucking below the rim. A few drops of detergent were added to bugs on cow peas, IITA, first season, 1983. 78 Grain Legumes reduce surface tension and cause the thrips to sink. The sticky traps were glass boiling tubes 20 cm Two drops of formaldehyde (40%) were added to long and 3 cm in diameter, with Tree Tangle Foot''' preserve the insects and prevent growth of algae or smeared on the interior. The tubes were placed in the fungi. Traps were mounted randomly on tripod stands field at crop level on upright wooden pegs. in the field about 22 cm above ground. Their height Sampling was also done with very fine nylon aerial was increased as the crop height increased. The traps net. Ten sweeps were made per sample, and a defined were left in the field for 9 to 10 hours, after which route was followed each time to avoid sweeping the thrips were counted in the field. same area twice. Sweep net catches were put in ethyl acetate containers for sorting and counting later in the laboratory. Number of bugs per 2m of row One raceme or one flower, depending on the age of 12.------------------------------, the crop, was collected from predetermined points at random from 10 plants and held in 30% alcohol. Thrips were then counted under a microproje·ctor. Plant-shake boards were constructed from sheets 10 of plywood 41 x 30 cm and about 0.5 cm thick. One side of each board was painted with white glossy paint and further divided into six grids of 100 cm2 to make it easier to count the thrips. At each sampling B transparent polyethylene sheets of the same dimen­ sions as the boards were pinned onto the painted sides of the boards. Slightly diluted Tree Tangle Foot./< glue was then applied evenly to the polyethylene 6 sheets. A board was placed beneath a plant selected as for the alcohol procedure during sampling. The plant was then tapped five times over the board. Thrips dislodged from the plant were trapped by the glue. 4 The efficiency of each of the five methods was ,,1 ', Drop clot~ \, computed on the basis of the relative variation statistic (RV). (See the definition of RV in the dis­ t"',... : \ cussion above on pod sucking bug surveys.) The I \ \ 2 I \ I \ relative efficiency of the five methods is shown in I \: \ Table 20. Twenty-five percent precision is considered ...... I \ , \ Visuol counts satisfactory for extensive surveys and 10% for in­ "'I V "' __ .... tensive studies of population dynamics. In this study only 10% precision was acceptable. Sampling thrips OL-_L~L--L--L--L--L--L--~~~ ~ ~ a 2 5 9 Q E 19 with the shaking board was more precise (the RV I---Oct.--+------Nov.----il ranged from 7 to 11) than the other methods. The traps collected a fair number of other important arthropods Sompling dote associated with cowpeas and may therefore be useful Figure 4. Fluctuations in the population of pod sucking for faunal surveys. Based on their mean RV values, bugs on cowpeas, IITA, second season, 1983. the alcohol (RV = 29.8%) and sweep net (RV =28.4%) methods were found inappropriate for sampling Table 19. Population composition of pod sucking bugs thrips. An experiment is now in progress that will on cowpeas, lIT A, 1983 evaluate simultaneously sampling precision, cost Drop cloth Visual count and relationships between absolute and relative density. - S.R. Singh and A.B. Salifu First Second First Second Species season season season season Host Plant Resistance Clauigralla percent Pod borer. Screening for resistance to pod borer tomentosicollis . . ...... 0.6 14.1 0 36.6 (Maruca testulalis) was continued with selections C. shadabi ............. 47.9 23.2 14.2 11.6 from the previous year. The larval population at Riptortu8 dentipes . ...... 6.9 0 50.8 3.3 IITA, 18 larvae per 20 flowers, is considered adequate Aspauia sp ... ........... 4.1 9.7 9.0 6.8 Nezara uiridula . . .. ..... 34.2 43.8 24.3 30.8 for field screening. A total of641·lines were screened, Anoplocnemis curuipes . .. 0 0 1.3 1.4 of which 151 were selected from different generations. Piezodorus guildini ..... 6.3 3.8 0.4 0 Selection from F 8 was based on flower infestation and Boerias deplanata ....... 0 1.1 . 0 7.4 pod damage. The seven lines selected will be further Cletus sp ............... 4.3 4.3 0 0 evaluated in larger, replicated plots (Table 21). The Acrosternum sp. 0.· .. .•• 0 0 0 2.2 other 144 selections will undergo further preliminary Relative variationa . ..... 18.6 23.3 22.5 29.0 screening. (Germplasm screening for resistance to ·See definition of relative variation (RV) in accompanying text. this pest is reported on page 72.) Grain Legumes 79 Table 20. Relative efficiency of methods for sampling cowpea thrips, 1983 Sampling Mean no. of thrips + S.E. Relative variation, % a method 39 43 47 51 55 39 43 47 51 55 Alcohol .......•......... 1.6 ±0.6 1.8 ±0.6 18.3±3.9 45.3 ± 11.8 14.0 ±3.5 40 36 22 26 25 Water trap .............. 89.3 ± 18.4 78.8±6.4 60.3 ±5.7 118.3 ±20.3 31.3±5.6 21 8 10 17 18 Sticky trap ....... ..... .. 9.2 ± 1.9 6.2 ± 1.1 37.2±8.5 29.6±8.1 4.8 ± 1.2 20 17 23 27 24 Plant shake. ............. 25.2±2.5 21.2 ± 1.1 50.2 ± 4.9 120.2±8.2 28.2 ±3. 1 10 5 10 7 11 Sweep net ............... 2.6 +0.8 9.3 +2.8 21.8 + 7.6 16.5 + 3.4 19.6 + 5.1 30 30 35 21 26 -Relative variation is corrected to the nearest whole number. Pod sucking bugs. In last year's work on re­ Table 22. Field screening of selected cowpea cultivars sistance to pod sucking bugs, two cultivars were for resistance to pod sucking bugs at two selected as possible breeding parents. This year 26 locations in Nigeria. cultivars, including the two selected in 1982, were IITA, screened under extremely heavy field populations of first season Mokwa, second season pod sucking bugs at UTA and Mokwa. Pod bug Percent Percent Bugs populations were sampled throughout the season, seed Damage seed Damage per2m and the percent seed damage was assessed just prior Cultivar damage indexa damage indexa ofrowb to harvest (Table 22). All entries were replicated TVu 1890 .. 2.5 0.07 19.5 0.27 22.1 twice. Any cultivar that reduced insect damage by TVx 7-5H .. 4.1 0.12 34.2 0.47 23.4 60% or more (that is, had a damage index of 0.4 or less) TVx 3343-03<: 6.4 0.15 18.6 0.25 18.9 was considered promising. TVu 6863 .... 6.8 0.19 40.2 0.55 20.1 Only the check cultivar had a significantly higher TVu 1 ....... 7.4 0.21 28.8 0.39 18.5 bug population than other entries. Any differences TVu 1560 .... 25.6 0.73 48.4 0.66 18.9 between the test cultivars can therefore be attributed TVu 3417 .... 21.9 0.62 55.1 0.75 24.0 VITA-4 ...... 3.8 0.11 75.6 1.03 23.4 primarily to the inherent genetic attributes of the TVu 4596 .... 27.1 0.37 15.5 cultivars and not so much to bug pressure. Based on IT 82E-9 ..... 29.0 0.40 17.9 the damage index values, the following cultivars Ife Brown . ... 35.1 1.00 73.3 1.00 38.3 were the top performers : TVu 1890, TVx 7-5h, TVx Mean ... . 14.3 46.8 21.1 3343-03E,TVu 6863 and TVu 1. During the second S.E .......... 2.2 8.2 2.9 season screening, TVx 3343-03E, TVu 1890, TVu 4596, aRatio of test cul tivar to Ife Brown (check). TVu 1 and IT 82E-9 had damage index values at or ~he drop cloth technique was used only at Mokwa. below 0.4. The composition of the pod sucking bug population generally differs between seasons (see the section on program.- L.E.N. Jackai population surveys). This may have caused some Flower thrips. The field screening techniques cultivars to perform differently during the two sea­ generally used do not permit a critical evaluation of sons, although in general this year's results were resistance to flower thrips (Megalurothrips sjostedti). similar to those of 1982. Other factors related to the Material selected from the field should therefore be locations may also have been important. TVu 1890 screened again under artificial infestation. has performed well at two locations during four test Tests were carried out on a mesh house screening seasons over two years. This cultivar will be tested in technique that should allow rapid evaluation of large plots next year and may be used in thehreeding resistance. Screening methods were tested on potted plants, all of the same age. There were five varieties: Table 21. Lines selected from field screening of TVu 1509 (resistant check), TVu 76 (susceptible crosses for maruca resistance, IITA, 1983 check), TVx 3236, Ife Brown and VITA-6. Each variety Resistance indexa was replicated ten times in a completely randomized First Second design. Entry Pedigree season season Several seeds of each cultivar were sown in each MRx301 ..... TVu946-1E X KL 17.1 24.0 pot, and the seedlings were thinned to one at 10 days MRx 1301. . .. KL X TVu 946-1E 21.7 29.9 after planting. At 13 days plants were sprayed against MRx 1802 . ... KL X TVu 946-1E 30.2 28.1 aphids, and at flower init iation a ll plants were trans­ MRx 2501. . .. KL X TVu 946-1E 25.8 28.7 ferred into a screenhouse and each caged in fine nylon MRx 3002.... KL X TVu 946-IE 18.0 29.0 mesh bags. MRx 3301.... KL X TVu 946-IE 11.2 29.9 When peduncles were about 2 ern long, each treat­ MRx 3901. . .. KL X TVu I 16.8 23.7 ment was infested with about 30 adult M. sjostedti. TVu 946 (res. check) ..... ....... '. . . . 6.7 25.2 VlTA-6 (susc. check. . . . . . . . . . . . . . . . 34.7 59.9 Seven days a fter infestation, each replicate was visually rated for thrips damage, which appears as alpr MW:a + TW:l ,where M = number of larvae Ilnd stipule browning/drying and as bud browning/drying Wi T = percent pod dnmut::c. and/or abscission. Samples of racemes and flowers 80 Grain Legumes were taken to assess thrips populations. A field trial Insecticides was run concurrently with the screen house experi· ments to measure thrips damage on the experimental Nine insecticides were evaluated at Ibadan during cultivars under field conditions. the two 1983 cropping seasons for control of three There was no significant difference in numbers of major cowpea pests, flower thrips (Megalurothrips thrips in racemes between the resistant cultivars sjostedti) , pod borer (Maruca testulalis) and pod TVu 1509 and TVx 3236 (Table 23). The susceptible sucking bugs (several species). The chemicals were TVu 76 was significantly different from the others. applied at weekly intervals on cowpea variety TVx There were positive correlations for thrips popu· 3236 with a knapsack sprayer. Each treatment had lation and damage index between field and screen­ four replications arranged in a randomized complete house results (1'=0.90 for thrips populations and block design. There was a control plot that received 1'=0.95 for damage index). This indicates that the no insecticide. Dipel was replaced with Sherpa + results of screenhouse and field evaluation closely Dimethoate in the second season because of poor agree and that resistance screening carried out in the results in the first. Good yields were obtained from all screenhouse reliably indicates cowpea resistance. treatments during both seasons. In the first season, Screen house evaluation also provides information on the best treatments were Cybolt, Cypermethrin, the mechanisms of resistance, which are not easily Decis + Dimethoate, Thiodan + Decis, Tamaron and ascertained from field screening.- S.R. Singh and Oftanol. In the second season, these treatments plus A.B. Salifu Sherpa + Dimethoate and Cypermethrin + Dursban performed well (Tables 24 and 25). Insect control was generally good during both seasons. Several of the test chemicals gave values Table 23. Thrips numbers and damage after artificial that were significantly better than those of the infestation of cowpeas, lIT A, 1983 unsprayed control. Based on the results for both Mean number of thrips seasons, the following treatments appear to be best Per raceme Per flower Damage for all species: Sherpa + Dimethoate, Cypermethrin Cultivar (7 DAIa) (10 DAI) indexb + Dursban, Thiodan + Decis and Decis + TVu 1509 .........•....... 2.9 3.6 1.2 Dimethoate. Cybolt and Zolone did not give good TVx 3236 ..... . ........ . .. 2.5 10.6 1.9 control of thrips in flowers; Zolone was also in­ IfeBrown . . . . . . . . . . , . . . . . 4.1 29.5 3.2 effective on pod sucking bugs. Zolone, Tamaron and VITA-6 .................. . 3.7 28.5 3.1 Oftanol fa iled to give good control of the pod borer. TVu 76 ........•.. _. ...... 8.5 31.4 4.1 Formulations with synthetic pyrethroids, alone or S.E ........... .. .. . . . . ... . 1.2 2.5 0.4 in combination with other groups of insecticides, LSD (5%) .. ..... .......... 3.6 7.3 1.1 generally gave best control of thrips and the pod borer , whereas the systemic organophosphates failed an Al = days after inrestation. twrhrips damage was rated on a scale of 1 to 5, with 1 - slight to control the borer satisfactorily. Only Zolone failed damage and 5 = heavy damage. to control pod sucking bugs. These results are similar to those reported in 1982. It should be noted that control plots had heavy thrips pressure, which prevented adequate flowering ' Table 24. Performance oCfoliar insecticides in and podding. As a result, the number of pod borers controlling cowpea pests, IITA, first and pod bugs tended to be lower than expected. The season, 1983 best compounds will be further tested in 1984.-S.R. Maruca Singh and L.E.N. Jackai larvae Percent Dosage. per 20 pod bug Yield, Integrated Pest Management Insecticide g a.i·lha ·flowers damage kglha Cybolt During the first cropping season of 1983, cowpea (Flucythrinate) .. 60 0.9 12.6 1,600 varieties TV x 3236 and IT 82E-60 were planted as a Decis + Dimethoate® 5 + 330 4.0 11.0 1,597 sole crop and intercropped in double rows with maize Tamaron®. . . ..... . 600 3.7 10.5 1,568 (Population 49) rows 1 m apart and given one of two Decis + Dimethoate 12.5 + 400 2.9 14.5 1,539 pest control treatments : insecticide protection or no Cypermethrin 400 .. 30 1.0 16.1 1,510 protection. These treatments were replicated four Oftanol®. .. .. . .... 500 5.3 15.2 1,490 Thiodan + Decis® . . 600 + times in 12- X 12-m plots arranged in a randomized 12.5 1.7 19.7 1,464 Zolone®(Phasolone) complete block design. Plant densities were as fol­ 210 6.3 33.2 1,133 Dipel®(Bacillus lows: TVx 3236, 67,000; IT 82E-60,133,000; and maize, thuringiensis) . . . . 1,000 5.9 42.0 1,015 40,000 plants per hectare. Control (unsprayed) 6.7 62.6 537 The racemes and flowers of IT 82E-60 had more flower thrips (Mega lurothrips .jostedti) than did Mean ............. 3.8 23.7 1,345 S.E ............. _. those of TVx 3236, and incidence of flower thrips was 0.6 4.3 107 LSD (5%) .. " ..... 1.8 12.4 310 consistently lower on intercropped TVx 3236 cow­ peas (Table 26). Differences between sole and in- Grain Legumes 81 Table 25. Field evaluation offoliar insecticides for control of three major cowpea pests in Nigeria, IITA, second season, 1982. Mean number of: Pod bugs Dosage, Flowers Thrips per Thrips per per 10m Maruca per Yield, Insecticide g a.i ./ha per plant 10 racemes 10 flowers of row 20 flowers kgfha Sherpa + Dimethoate®. .......•...... 30 + 250 17.6 0 19.1 2.7 0 1,622 Thiodan + Decis® ...... ...... . ... . .. 500 + 10 24.3 2.7 54.8 18.0 0.1 1,613 Cybolt® (Flucythrinate) .............. 80 15.5 6.5 121.1 55.5 0.1 1,603 Oftanol® ........................... 500 12.9 0.1 23.4 39.2 4.6 1,589 Zolone® (Phasolone) ...... . . . ..• . . ... 700 14.3 0.9 112.3 111.7 3.0 1,587 Thiodan + Decis® ................... 650 + 10 15.3 1.2 39.5 17.0 0.2 1,586 Cypermethrin + Dursban® .... . . . .. .. 25 + 500 20.3 1.4 44.9 29.5 0 1,579 Decis + Dimethoate® ........... . .... 12.5 + 400 18.8 1.6 37.1 21.7 1.4 1,486 Cypermethrin + Dursban® . ... . . ... .. 50 + 500 20.1 0 32.7 22.2 0.1 1,440 Cybolt® (Flucythrinate) . ...... ..• ... . 40 15.7 8.4 131.1 28.9 0.3 1,433 Hostaquick® ...... . .......... . .. .... 550 12.4 6.0 170.0 38.5 2.2 1,397 Tamaron® .. .......... ... .. . .... , ... 600 14.7 4.5 43.4 10.7 3.1 1,397 Control (unsprayed) .....•...... . ... . 4.1 81.1 423.6 16.0 2.4 268 Overall mean .. ...... ..... ..... .. . .. 15.9 8.5 102.5 31.9 1.5 1,441 LSD (5%) ........ .... ......... .. . . . . 6.7 4.2 80.7 47.7 2.2 366 tercropping were less marked with IT 82E·60 and were replicated four times on 200-m2 plots. significant only at 30 and 37 days after planting. The racemes of both TVx 3236 and IT 82E-60 had Incidence of pod borer (Maruca testulalis) was low more thrips during the second season than in the first in this trial and did not differ significantly across (Tables 26 and 27). The incidence of thrips was again treatments. Of the pod sucking bug species known to consistently lower on TVx 3236 than on IT 82E-60, and attack cowpeas, only Riptortus dentipes occurred in the racemes of intercropped TVx 3236 had signifi­ significant numbers (Table 26). TVx 3236 had sig­ cantly fewer thrips than the TVx 3236 sole crop; this nificantly fewer riptortus when intercropped than was not true for IT 82E-60 in the second trial. when sole cropped. The lower incidence of riptortus The incidence of pod borer was markedly higher on IT 82E-60 is explained by the lower number of pods, during the second season; up to 67% of flowers were a result of thrips damage, which caused more flower found to be infested. TVx 3236 flowers had fewer abscission on this variety. maruca larvae than those of IT 82E·60 (Table 27). In Cowpeas gave zero yield in all the unsprayed contrast to the data on flower thrips occurrence, the treatments because of damage from flower thrips and flowers of intercropped cowpeas had significantly pod sucking bugs. Among the sprayed treatments, more maruca larvae than did those of the sole crops of intercropped TVx 3236 and IT 82E-60 yielded 543 ± f 3 both TVx 3236 and IT 82E-60. Maruca larvae from the and 199 ± 29 kg/ha, respectively-that is, only 35 and samples were reared on an artificial diet to assess 37% of the sole crop yield (1,548 ± 93 and 528 ± 134 maruca parasitization under the different cropping kg/hal-mainly because of shading by maize. Maize yield averaged 4,260 kg/ha and showed no differences between treatments.' These preliminary results from Table 26. Effect of intercropping on incidence of the first season suggest that intercropping may cowpea insect pests, IITA, first season, 1983 reduce thrips pressure but that without insecticide TVx 3236 TVx 3236 IT 82E-60 IT 82E-60 application intercropping is not likely to improve sole + maize sale + maize yields. Thrips per 10 racemes number ( ± S.E.) In a follow-up trial during the second cropping 30DAP' . 18.8 ± 1.0 14.3 ± 1.1 48.1 ± 1.9 31.3 ± 1.9 season of 1983, intercropped TVx 3236 and IT 82E-60 37 DAP .. 18.5 ± 1.7 8.2 ± 1.1 51.3 ± 5.9 27.9 ± 3.3 cowpeas were planted in a different arrangement of Thrips per 10 flowers four cowpea rows 0.5 m apart, alternated with double 44 DAP . . 54.1 ± 9.6 25.5 ± 4.9 130 ± 20 107 ± 18 51 DAP .. 91.2 ± 8.4 61.7 ± 5.0 177 ± 20 141 ± 24 rows of maize (TZESR-W) to lessen the shading of Flowers per m of row cowpeas by maize and to better expose the cow peas to 45 DAP . . 19.7 ± 2.4 6.6 ± 1.2 4.8 ± 1.1 3.0 ± 0.8 insecticide spraying. The plant densities were the 54 DAP. . 7.7 ± 1.1 1.7 ± 0.5 2.8 ± 0.9 2.1 ± 1.1 same as in the first season experiment. The inter­ Maruca per 10 flowers cropped cowpeas and both cowpea and maize sole 44DAP .. 0.8 ± 0.2 0.5 ± 0.2 1.4 ± 0.2 1.5 ± 0.3 crop checks were given two pest control treatments: 51DAP .. 0.8 ± 0.2 1.5 ± 0.3 1.7 ± 0.5 1.0 ± 0.3 full insecticid.e protection (four sprays of Decis/ Riptortus per 12 m ofrow Dimethoate at 15 + 400 g a.i. /ha) or minimum insec­ 52DAP .. 2.6 ± 0.4 2.2 ± 0.3 0.1 ± 0.1 0.1 ± 0.1 ticide protection (one spray of Nuvacron at 200 g a.i. 59DAP . . 6.1 ± 1.2 2.0 ± 0.5 0.4 ± 0.2 0.1 ± 0.1 and one of Decis at 15 g a.i. /ha). These treatments "DAP = days after planting. 82 Grain Legumes systems. Two larval parasites, Braunsia sp. and istis was infesting up to 2% of plants. The cropping Phanerotoma sp. (Braconidae), emerged in significant system did not affect damage significantly. numbers (more than 10% of larvae infested, on the Intercropped cowpea yields averaged 60% of the average), but differences between treatments were sole crop yields for both TVx 3236 and· IT 82E-60; not significant. intercropped TZESR-W maize yielded, on the aver­ Of the diiferent pod sucking bugs present during age, 70% of the sole crop (Table 28). The resulting the second season, Clavigralla spp. were the pre­ relative yield totals ranged from 1.2 to 104. It may be dominant ones (see also the section on insect sur­ concluded that the crop arrangement of the second veys): IT 82E-60 had significantly fewer Clavigralla trial was more profitable than that of the first. spp. than did TVx 3236 (Table 27). The effect of Further work is planned to assess the effect of cropping system was evident only with TVx 3236, in cropping system and insecticide spraying on the which intercropping reduced the incidence of parasites of maruca larvae and eggs of pod sucking Clavigralla spp. significantly. This is consistent with bugs and to determine whether increased parasite the data on Riptortus dentipes infesting TVx 3236 incidence, together with reduced thrips and pod bug . during the first season trial. pressure, will reduce the optimum chemical control Disease incidence on cowpeas was rated for both input in agronomically viable mixed cropping varieties at 50 days after planting (Table 27). It was systems.- F. Wiedijk found that, whereas TVx 3236 was virtually disease free, IT 82E-60 was infected by several diseases: leafspot (Cereospora eruenta), bacterial pustule Pathology (Xanthosoma sp.), anthracnose (Colletotriehum lin· Surveys were carried out in all cowpea growing areas demuthianum) and brown blotch (Colletotriehum of Niger to collect information on the distribution eapsici and C. truneatum). Except for brown blotch, and importance of cowpea pathogens. Charcoal rot, these diseases occurred significantly less on inter­ caused by Maerophominaphaseolina, was found to be cropped than on sole cropped IT 82E-60. the most widespread and important disease, causing Maize borer damage was rated at 16, 24 and 60 days up to 70% seedling mortality in areas of southern after planting. At 16 days Buphonella sp. was found Niger and total crop loss in areas ofthe North. Other to cause minor damage (up to 3% of maize plants diseases of economic importance in the South were infested); later ratings showed that Sesamia ealam· brown blotch, web blight, bacterial blight and Table 27. Effect of intercropping on incidence of cowpea insect pests and diseases, lITA , second season, 1983 TVx 3236 TVx 3236 IT 82E·60 IT 82E·60 sole + maize sole + maize No insecticide spray number ( ± S.E.) Thrips per 10 racemes 30 DApa .................. _. .. _ .. _ ... .. .. _ ... _. 96.1 ± 10.1 108.7 ± 8.7 36 DAP· .... .......... .. .. _ ... _ .. _ ... _ ... _ ... _ . 157 ± 14.0 136 ± 13.0 38DApb .. ... .... ........ _. .. _. ..•...... . ...•. 50.7 ± 2.7 36.4 ± 2.5 44DApb .... ........ . .... • ...• .. .. ............ 118.5 ± 5.4 92.1 ± 7.1 Racemes per meter of row 30DAp· ................. .....•. ..• ........... . 67.4 ± 3.0 79.4 ± 4.5 38DApb ..........................•......•... . . 102 ± 5.0 100 ± 5.0 One spraying ofNuvacron Maruca per 20 flowers 44DApc ... ......... ...... .... • ...• . . . . . .• • . .•. 11.5 ± 0.7 14.0 ± 0.7 52DApd . ... ......... ...... .. .•...... . .......•. 5.3 ± 0.4 6.7 ± 0.8 Flowers per meter of row 44DApc ........ ..................•...•.. .. .. .. 28.5 ± 3.1 22.2 ± 2.8 52DApd ...................................... . 8.0 ± 1.2 9.0 ± 1.1 Percentage of flowers infested . ............. . ..... . . 24.8 ± 1.7 30.3 ± 3.2 51.6 ± 3.3 67.0 ± 3.3 One spraying ofNuvacron followed by one of De cis Clavigralla spp. per 20 m at 57 DAP .............. . . . 4.6 ± 0.7 1.3 ± 0.3 0.3 ± 0.2 0.4 ± 0.2 Pods per meter of row at 57 DAP .. .......... ....... . 28.3 ± 4.8 32.3 ± 3.4 29.0 ± 3.0 27.1 ± 2.5 Clavigralla spp. per 1,000 pods ..... . ............... . 8.1 ± 1.2 2.0 ± 0.5 0.5 ± 0.3 0.7 ± 0.4 Disease incidence (percent of crop infected) at 50 DAP Leafspot .. .................................. . . o 0 67.5 ± 8.1 "46.3 ± 4.1 Bacterial pustule . ......................... .... . o 0 46.3 ± 10.8 20.6 ± 8.9 Anthracnose . .................. ... .............. . o 0 49.4 ± 4.6 35.0 ± 5.0 Brown blotch .. .... ........................ ... . o 0 50.0 ± 6.1 60.0 + 7.2 aNa racemes for sampling on TVx ~236. bNo racemes for sampling on IT 82E·60. cNo flowers for sampling on TVx 3236. dNo flowers for sampling on IT 82E-60. . Grain Legumes 83 Table 28. Effect of interc ropping and insecticide on antiserum with a titre of 1/1,024 in microprecipitin cowpea and maize yield, lITA , second tests. A gamma globulin coating of 1 J1g protein/ml seaso.n, 1983 and a conjugate dilution ofl/250 proved to be the best Yield, combination. When an extraction buffer consisting of Treatment kg/ha (+ S.E.) RYT8 0.25 M potassium phosphate (pH 7.5) with 0.1 M Sole cropped TVx 3236 EDTA and 0.25% sodium sulphite was used, positive Full insecticide protection , , , ' , . 1,283 ± 25 reactions were obtained up to a dilution of 1/625 with Minimum insecticide protection ., 885 ± 130 infected young cowpea plants (TVu-76) at 10 days Intercropped TVx 3236 after inoculation. Serial dilutions of infected N. Full insecticide protection ..... . 640 ± 103 1.21 benthamiana leaves were also tested, and positive Minimum insecticide protection 577 ± 29 1.36 reactions were obtained up to a dilution of 1/625. Sole cropped IT 82E-60 Full insecticide protection . .. .. . 1,014 ± 43 When old infected leaves (20 days after inoculation) Minimum insecticide protection . 480 ± 90 were tested, positive results were obtained only up to Intercropped IT 82E-60 a dilution of 1/125. More detailed tests, using more Full insecticide protection ..... . 613 ± 61 1.31 tolerant varieties at different stages, are needed to Mini+num insecticide protection. 279 ± 63 1.29 determine whether CAbMV can always be detected in Sole cropped TZESR-W .... ' .' '. .... . 2,180± 172 cowpeas by ELISA.-G. Thottappilly Intercropped TZESR-W ....... ', ' . " 1,543 ± 166 Cucumber Mosaic Virus 8Relative yield total (= LER for this trial). Further host range and serological studies of tfie Cercospora leaf spot. In the North the parasitic plant cucumovirus occurring in cowpeas and lima beans in Striga gesnerioides was found to be important, in Nigeria have revealed that this virus should be addition to Septoria and Cercospora leaf spots. considered a strain of cucumber · mosaic virus The large number of progenies in the cowpea (CuMV). Although host range differences exist be­ breeding program has made it necessary to develop a tween this and other CuMV strains, the differences rapid and efficient inoculation technique for screen­ are equally large between a ll strains compared. In all house evaluation for resistance to brown blotch cases, however, Nicotiana glutinosa and Cucumis disease. This technique will permit early selection of sativus produce systemic symptoms. A close serologi­ desirable material for further genetic improvement. cal relationship was found between our cowpea Two hundred and fifty-three lines tested in the pre­ isolate and CuMV isolates obtained from various liminary and initial evaluation trials were screened crops in temperate regions. in the greenhouse for resistance to several diseases of CuMV is widespread in cowpeas in Nigeria. It is the humid tropics. It was found that there is a high difficult to identify the disease solely on the basis of level of resistance to Cercospora leaf spot, a disease plant symptoms, and agar gel diffusion tests with that usually becomes evident 'a fter flowering. A fair crude sap from cowpeas have given inconsistent re­ level of resistance to bacterial pustule, bacterial sults. To produce a more reliable diagnostic method, blight and web blight is also available, although the direct (double antibody sandwich) ELISA method there are indications that the resistance may be was developed and tested. dilute in certain cases, as in preliminary trial 1 and An antiserum against CuMV was produced after initial evaluation trials 1, 2 and 3 (Table 29). Since purification of the virus from N. glutinosa, using web blight can be a serious problem in the first season phosphate buffer, PEG precipitation, differential under high humidity, particular attention will be centrifugation and sucrose density gradient centri­ given to screening for field resistance to this disease. fugation. The antiserum had a titre of 1/128 in agar There are indications that Colletotrichum capsici, gel diffusion tests using purified virus as an antigen. the causal organism of brown blotch disease, pro­ However, the antiserum also reacted up to a 1/8 duces new biotypes at a high frequency. The fre­ dilution with sap from ' healthy cowpea plants. To quency of resistance in the lines screened so far is not remove the antibodies against healthy plant proteins, high enough to match the high rate of mutability in the antiserum was repeatedly absorbed with sap from the organism. Screening under field and greenhouse healthy cowpea leaves until no further precipitate conditions will therefore focus on deploying host was formed. The gamma globulin fraction from the absorbed antiserum was purified by ammonium sul­ resistance genes.-V. Parkinson fate precipitation and by filtering through a column Virology of DE 22 cellulose. A gamma globulin coating of 1 J1g protein/ml and a conjugate dilution of 1/250 pro­ Cowpea Aphid Borne Mosaic Virus vided the best results with infected cowpeas and In the past it has proven difficult to detect cowpea N. glutinosa. It was also possible to detect CuMV in aphid borne mosaic virus (CAbMV) in cowpeas by frozen tissues as well as in cowpea leaves, which were means of SDS agar gel diffusion tests or ELISA (lITA , dried over calcium chloride. Using crude juice from Annual Report for 1982). To provide a reliable, quick infected cowpeas, it was possible to detect the virus method for identifying CAbMV, direct (double anti­ up to dilutions varying between 1/625 and 1/3,125.­ 'body sandwich) ELISA was developed, usihg an G. Thottappilly and J. W.M. van Lent 84 Grain Legumes SAFGRAD Project The insensitive varieties were evaluated in ten trials: three advanced, · five preliminary and two Genetic Improvement international yield trials. Variety Trials Preliminary yield trials_ Five trials, three con­ sisting of medium and two of extra-early maturing In these trials a range of photoperiod sensitive and lines, were conducted in Upper Volta. Two of the insensitive materials were evaluated that vary in medium maturing variety trials- preliminary trials 3 plant type, maturity and seed characteristics. The and 4-came from UTA and the third from Upper first trial consisted of 28 photoperiod sensitive var­ Volta. The yields of the trials from UTA (both con­ ieties, all of which had rough seed coats. The trial ducted at Kamboinse) were generally low owing to was planted at Farako-Ba and Kamboinse (which drought stress. The trial from Upper Volta was represent the Guinea and Sudan savanna zones, conducted at three locations; the yields of the most respectively) in a randomized block design with four promising lines are listed in Table 30. The yields at replications. The plots had four rows 4 m long, with Pobe, which is in the Sahel, were very poor because of interrow spacing of 75 cm. The most promising extremely low rainfall. At Loumbila, where there was varieties were TVx 6486-36B1-K, KVu 20-2, KVu 12-2, more moisture, the lines performed satisfactorily. KVu 18-1 and TVx 6486-12B1-K, yields of which The highest yielding line was TVx 4659-13C-1K, ranged from 1,137 kg/ha to 1,417 kg at Kamboinse which had an average yield of 1,277 kg/ha. and 798 to 1,111 kg at Farako-Ba. Although the best Two preliminary yield trials consisting of extra­ varieties did not differ from each other in yield, they early maturing varieties were received from UTA and did yield significantly more than the local check. evaluated at Loumbila. The performance of the most Table 29. Reaction of breeding lines to some important cowpea diseases, IITA, 1983 Disease frequency. % Plant response Cercospora Cercospora Bacterial Bacterial Web to inoculation canesens cruenla pustule blight blight Preliminary trial I Resistant . .............. . ...... . .................... . 72 94 44 39 39 Moderately resistant . .... . . ..... . .............. . ... . . . 11 6 17 55 33 Susceptible ............. . ..... .. ... .... . .......•. .... 17 0 39 6 28 Preliminary trial II Resistant . ....... .... ....... .... .. ... . . . . . ..... .. ... . 81 87 82 65 31 Moderately resistant . ..... . .. ... . .. .. .. ... ... .. ... .. . . 19 13 6 23 50 Susceptible .... ........... . . _. .. _. .. .. . . .. . . . . ..... . . 0 0 12 12 19 Preliminary trial III Resistant . .... .. ........... ... ........ . . . . ... ...... . . 78 89 60 44 29 Moderately resistant . ........ . ... .. ...... . .... . .. .. .. . 22 0 33 44 50 Susceptible ....... ... ....................... . ... . .. . . 0 11 7 12 21 Preliminary trial IV . Resistant . ..................... ..... . . .......... . ... . 95 89 68 63 53 Moderately resistant . .. ..... .. ............ . ... . ...... . 5 11 11 26 26 Susceptible . .... ..... ... ..... . .. .. . . .. . . . . ... .. .. . .. . 0 0 21 11 21 Initial evaluation trial I Resistant . .......................................... . 81 80 47 67 62 Moderately resistant . .................. . .......... . .. . 15 18 30 29 30 Susceptible ..................... _ ..... . ............. . 4 2 23 4 8 Initial evaluation trial II Resistant . ............ ... .......... . .............. . . . 76 51 36 33 96 Moderately resistant . .... ..... ............... . . .. . . .. . 16 29 8 53 4 Susceptible ............................ . ....... ... .. . 8 20 6 14 0 Initial evaluation trial III Resistant . ............. ..... .... . ... .. .............. . 54 53 71 43 68 Moderately resistant . ................ . ... . ...... .... . . 38 45 27 57 30 Susceptible .................. . ............ .... _ .... . . 8 2 2 0 2 Initial evaluation trial IV Resistant . ........ . .......... . . . . . . .. ....... . . . ..... . 71 85 26 77 93 Moderately resistant . ........... .. . . .. .. .. .. . .... . . . . . 19 4 17 21 7 Susceptible ..... ........... _ .. . . __ . _ ... . . .. .. .. .. . . . _ 10 11 57 2 0 Grain Legumes 85 Table 30. Performance of cowpea lines in a preliminary yield trial at various locations in Upper Volta, 1983 Yield, kg/ha Days t.o 50% flowering Variety Farak.o·Ba L.oumbila P.obreFarak.o·Ba Loumbila P.obre KVu 69 ....... ... . . ............. ... . ....... '. . . . 1,031 1,633 344 40 35 39 KVu 72.. .. . . . .. . .. . .. • .. . . . . . . . . . . .. . . .. . . .. . . 1,084 1,928 275 49 33 59 KVu 76. . . . . . . . • . . . . . . • . . . . . . . . . . • . . . . . . . . . . . . . 1,076 1,328 498 46 40 40 KVu 131. . . . . . . . . . . • . . . . . . • . . . . . . . . . . . . . . . . . . • . 829 2,528· 269 47 40 45 KVu 150. . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . 754 2,378 276 53 50 59 KVu 77. . . . . . . . . . . . . . . . • . . • • . . • . .. • . . . . . . . . . . . . 593 1,527 632 47 41 42 TVx 4659·13C·IK ...... .. .. . •. . • . ..... . .. .. .. .. . 1,339 2,156 336 47 39 43 IT 82E·60 . . . . . . . . . . . . .. • . . . .. . . . . . .. .. • . .. • . . .. 533 1,400 466 43 38 37 Local check ........•..... • •......• . ..•...•...• 728 1,606 296 46 35 58 Trial mean ............•....................... 738 1,420 457 46 39 43 LSD (5%) ..................... ............ .... . 298 630 225 2 9 8 C.V., % ........... . .......................... . 25 27 31 3 14 11 promising lines is given in Table 31. In trial 1 the and IT 81D·1137 were the best varieties. Yields at highest yielding line was IT 82D·636, although its Kamboinse were low owing to drought at flowering. yield did not differ significantly from that ofT V x 3236. Twenty·five sets of the second trial, consisting The best lines in trial 2 also performedabout as well of nine early maturing varieties contributed by as TVx 3236. Senegal, IITA and Upper Volta, were also sent to 16 Advanced yield trials. Three trials consisting of countries. The performance of the lines in Upper medium maturing lines were conducted: two from Volta is shown in Table 34. On the average over all IITA were planted ai Kam boinse and a third from three locations, TVx 4654·13C·IK was the best var· Upper Volta at four locations. The best lines in trial 1 iety, yielding 1,436 kg/ha. IT 82E·18 and 82E·32 were IT 8lD·I05, 8lD·1039, 8lD·1054, 8lD·1063 and yielded an average of 1,230 and 1,143 kg/ha, TVx 1948·012F, with yields ranging from 719 kg/ha to rcspectively.-V.D. Aggarwal and I. DrabD (VDltaic 946 kg. The best performers in trial 2 were IT 81D·975, Institute .of Agricultural and Animal Research) 8lD·1189·81, 8lD·1137, 82D·716 and TVx 3236·5·2; their yields ranged from 658 kgjha to 944 kg. The lines Insect Resistance in trial 1 had smooth seed test.ae, and those in trial 2 Bruchids. One objective of SAFGRAD's genetic mainly had rough seed testae, the preferred type in improvement work is to develop bruchid resistant Upper Volta. The yields and seed characteristics of the best lines in the trial from Upper Volta are Table 31. Results of lITA preliminary trials at presented in Table 32. The highest yielding line was Loumbila, Upper Volta, 1983 KVx 30·309·6G, which averaged 27% more than the local check. The best lines were ofthe preferred seed Dayst.o 50% Variety flowering Yield, kg/ha color and size. International trials. Two trials from IITA were Trial 1 IT 82D·636. . .. . . . . .. . . . . . . . . .. . .. 52 2,269 planted at Loumbila, Upper Volta. International trial IT 82D·640. . . .. . . . . . . .. . . . . .. 40 2,084 1 consisted of 10 extra·early maturing var ieties, the IT 82D·641. . . . . . . . . . .. . . . .. . . . . .. 39 2,140 yields of which are listed in Table 33. The yields of the IT 82D·654. . . . . . . .. . . .. . . . . . . . . .. 37 1,927 best five varieties of the 20 medium maturing var· IT 82D·673. . . . . . . .. . . .. . . .. . . . . .. 46 2,067 ieties in trial 2 are also listed in Table 33. The lines IT 82E·60. . . . . . . . . . . . .. . . .. . . . . .. 38 1,160 generally performed well in both trials, particularly TVx 3236... . . ... . . . . . . . . . . . . . . .. 38 2,226 the early maturing one, owing to favorable rainfall. Tria} mean. . . . . . . . . . . . . . . . . . . 39 1,657 Regional trials. The objective of these trials was LSD (5%) .. .. .. .. .. .. .. .. .. . 6 606 to test promising cowpea varieties from different C.V., % ......................... 12 26 national, regional and international programs in the Trial 2 semiarid environments of various SAFGRAD memo IT 82D·871. . . . .. .. . . . .. .. .. . . . . .. 40 1,987 ber countries. In 1983 two regional cowpea variety IT 82D·872. . .. . ... .. .. .. . .. .. . . .. 42 1,824 trials were conducted, the first consisting of 15 IT 82D·874. . . . . .. . .. .. .. .. .. .. . .. 42 1,824 medium maturing varieties contributed by national 11' 820·885. . . . . . .. .. .. .. .. .. .. . .. ~5 1,851 programs in Nigeria, Senegal, . Niger, and Ethiopia 1'1' 82U·889. . . . .. . • . . . ... . .. . .. . .. 34 1,530 IT 82E·60. .. . . . . . • . .. .. . .. . .. . . .. 38 1,360 and by IITA's programs in Nigeria and Upper Volta. TVx ~236.......... .. ............ 42 2,010 Twenty·seven sets of this trial were sent to 16 coun· tries. The yields of the 15 varieties in the trial Trial mean ......•...•.. . •.. . .... 38 1,642 conducted in Upper Volta are listed in Table 34. On LSD (5% ) .............. . ....... . 2 351 the average over all locations, SUVITA·2, IT 82D·952 C.V.,IX) ... ·· .... .. · ............ . 4 15 86 Grain Legumes Table 32. Yield and seed characters of cowpea lines in an advanced trial at locations in Upper Volta, 1983 Yield, kg/ha l00-seed Seed color Cultivar Farako·Ba Kamboinse Pabre Saouga weight, g and texture8 KVx 30·309·6G . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 1,042 1,369 1,288 833 20 WR KVx 30·124-9G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,040 1,188 899 708 25 WR KVx 30·230·2G. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,035 920 1,464 729 19 WR KVx 30·523·2G. . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . 1,031 l~a WI ~ ~ WR KVx 30·470-3G. . . .. .. . . . . . . .. . .. . . .. . .. . .. .. . . 873 929 1,553 729 21 WR KVx 30·305·3G . . . . . . . . . .. . . .. . .. . .. .. .. .. .. . . . 979 1,493 987 646 27 WR UV·TVx 5050·02C·K . . . . .. . . .. .. .. . .. .... .. .. .. 1,094 776 680 406 24 WR Checks; SUVITA·2 ............... .... ........ ...... . 660 896 1.243 771 20 BR KN·l .........•...... . ..................... 680 637 1.129 188 14 TS TVx3236 ................. . .. . ... . ... ...... . 789 587 1.280 560 11 CR Trial mean . ............ . .......... . ......... , 908 960 1.025 543 LSD (5%) ................................... . 280 336 412 310 C.V.,% ..................................... . 22 25 28 8 ·W = white, B = brown, T = tan, C = cream, R = rough and S = smooth. varieties that have good seed quality, high yields and ofthe best 10 lines is shown in Table 35. All these lines wide adaptation. F, progenies derived from crosses were derived from a single cross between TVu 2027 involving TVu 2027. Worthmore. KN·l and Local and SUVITA·2. Except for KVx 30·GI56·6-9K, all the Kamboinse were screened for bruchid resistance. In lines had seed characteristics that are acceptable to addition, lines selected in 1982 for bruchid resistance consumers in Upper Volta, and their level of reo were evaluated for their agronomic performance. sistance to bruchids was comparable to that of TVu Two yield trials consisting of bruchid resistant 2027. Some of the lines yielded as well as the lines were conducted at three locations in Upper high yielding checks. Volta. The first trial had 144 lines planted in single· In the second yield trial' (international trial 3 from row plots 4 m long and 1.5 m apart. Entries were IITA), nine bruchid resistant lines and a local check arranged in a 12 X 12 simple lattice. The performance were evaluated at Loumbila in a randomized com· plete block design with four replications. The plots Table 33. Performance of varieties in international had four rows 4 m long. As shown in Table 36, yield trials at Loumbila, Upper Volta,1983 the general performance of these lines was good; Days to 50% IT 8lD·985, 8lD·988. 8lD·994 and 8lD-I064 yielded Variety flowering Yield. kg/ha significantly more than the local check. With the exception of IT 81D·I064. the highest yielding lines Trial 1 are of good seed quality. IT 82E· 77. . . . . . . .. . . . .. . .. . . .. . .. 36 1.514 IT 82E·9 ....................... .. 34 1.663 Aphids. Resistant lines selected in 1982 were . IT 82E·41. .. . . .. . .. .. .. . . . . .. . . .. 35 1.497 evaluated this year in a replicated yield trial consist· IT 82E·13 ...... ... . ... .. ....... ,. 39 2.428 ing of 144 lines at Farako·Ba, Kamboinse and Pobre, IT 82E·16.. . . . .. . . . . ... . . . • . . . ... 39 2.252 At each location the experimental design was a 12 x IT 82E·18. . . .. .. . . . . . .. .. .. . . . . .. 38 1.906 12 simple lattice. and the plots were single rows 4 m IT 82E·32. . . .. .. . . .. . .. .. .. . . . . .. 39 2.392 long and 1.5 m apart. As shown in Table 37, the most IT 82E·56.. . . . .. .. .. . .. .. .. . .. . .. 35 1.441 IT 82E·6O. . . . . . .. .. .. . .. .. .. .. . .. 36 1.490 promising ofthe lines yielded as well as the best check Local check .. .. .. .. .. .. .. .. .. ... 33 1.477 variety, All 144 entries are currently being screened for resistance to aphids under artificial infestation, Trial mean. . . . . . . . . . . . . . . . . . . . .. 36 1.606 Those which are aphid resistant and high yielding LSD (5%) ............ .. ......... 1 454 C.V .• %. . .................. ... .. will be selected for further use in the breeding 2 17 program. Trial 2 Seven new crosses involvin·g aphid and thrips IT 8ID·1205·174 . . . . . . . . . . . . .. . . .. 43 1.261 resistant lines. derived from the triple crosses (KN·l TVx 4654·44E . . . .. . .. . .. . . .. .. . .. 42 1.221 x TVu 36) x TVx 3236 and (SUVITA-2 x TVu '36)-x TVx 4659·03E .. . . . .. .. . . . . .. . . ... 44 1.081 TVx 4677-88E .. . . . . .. . . .. . . .. . ... 44 TVx 3236 and the backcross KN-l (KN·1 x TVu 36), 1.032 TVx 3236-0\G. . .. .. . .. .. .. . .. . . .. 42 1.077 were made to incorporate aphid and thrips resistance Local check .. .. .. .. .. .. .. .. .. ... 35 909 into lines with desirable seed and agronomic traits. Populations of each cross were screened for resist· Trial mean. . . . . . . . . . . . . . . . . . . . .. 41 941 ance to aphids and thrips under natural infestation. LSD (5%) ....................... 2 213 C.V .. %. .......... . .. ........... 3 Selected plants will be evaluated in 1984. Progeni,es 16 from double crosses involving bruchid, aphid and Grain Legumes 87 thrips resistant parents are also being evaluated for Table 34. Results of regional trials at three locations resistance to the three insects. in Upper Volta, 1983 Thrips. Crosses involving two thrips resistant Yield, kg/ha lilies, TVu 1509 arid TVx 3236, ' were made to in· Kam- corporate thrips resistance into promising lines. Variety and origin Farako-Ba boinse Pobre The populations of each cross were screened in the Medium maturity field under natural infestation using a susceptible IAR 48, Nigeria ................ 1,023 687 721 spreader line planted three weeks earlier. Plants that Mougne, Senegal .. ............. 1,044 681 598 produced pods were harvested individually and will TN 88·63, Niger ................ 1,073 657 493 be screened again in 1984.- V.D. Aggarwal and Y.S. White Wonder Tr., Ethiopia .. ... 1,459 305 295 Rathore SUVITA·2, UTA/Upper Volta .... 1,146 1,045 597 TVx 3236, UTA/Upper Volta ..... 1,148 475 676 Striga Resistance . KN·l, UTA/Upper Volta ........ 1,123 504 363 TVx 1999·01F. UTA/Upper Volta. 1.267 676 650 Several segregating populations were screened for TVx 4262·09D. UTA/Upper Volta. 626 489 334 resistance to Striga gesnerioides; uninfested plants IT 8lD·994. UTA/Nigeria ........ 1.292 446 18 were selected and will be reevaluated in 1984. IT 8lD·U57. UTA/Nigeria ....... 1.209 680 568 Advanced striga resistant breeding lines selected last IT 8lD·1137. UTA/Nigeria ....... 1.428 645 635 year were entered in a regional cowpea striga trial IT 8lD·952. !ITA/Nigeria ........ 1.000 624 850 TVx 4659·03E .................. and sent to five countries. At Kamboinse the trial was 1,228 644 451 Local check ................... 699 41 13 conducted ina striga sick plot. Two susceptible and two resistant varieties were used as checks. The Trial mean . ................... 1.U8 572 492 experimental design was a randomized complete LSD (5%) ..................... 352 294 208 . block with three replications. C.V .• % ....................... 22 36 30 The performance of the seven most promising lines Early maturity is given in Table 38. Striga emergence was delayed in IT 82E·18. UTA/Nigeria ..... .. .. 1.100 1.844 746 the promising lines, and the percentage of striga IT 82E·32. UTA/Nigeria ......... 1.223 1.536 670 infestation in them was low. Their yield was compar· IT 82E·32. UTA /Nigeria ....•.... 751 1,100 583 able to that of the resistant varieties. Although the IT 82E·60, UTA/Nigeria .... , .... 685 1,315 479 IT 82E· 70, lITA /Nigeria .. .. .... . percentage ofstriga emergence in TN 88·63 was high , 762 1,459 629 Bambey·21, Senegal . ......... .. 734 1,261 529 this was not reflected in the yield, suggesting that this KVu 69, Upper Volta .... , .... .. 903 1,513 935 variety is tolerant to striga. TVx 4659·13C·1K. Upper Volta ... 1,221 2,071 1,015 The inheritance of resistance to striga was studied Local check ................... 582 1.330 80 in F" F 2 , BC, and BC 2 segregating populations from Trial mean . ................... 885 1.492 a cross between Kaya Local and SUVITA·2 and in 630 LSD(5%) ..................... 399 377 146 parental ·material. The experiment was planted in a C.V.,% ............... , ... , ... 3 17 16 Table 35. Performance ofbruchid resistant cowpea lines at various locations in Upper Volta, 1983 Seed Percent Days to 50% flowering Grain yield, kg/ha color bruchid Kam- Karn- 100·seed and resistance Cultivar Farako·Ba boinse Pobre Farako·Ba boinse Pobre weight, g texture at60DAI8 KVx 30·G 183·3·5K ....... .. 55 47 49 593 820 962 25 BR 92.5 KVx 30-G467·5·10K ..... . .. 51 45 45 726 840 625 27 BR 95.0 KVx 30·G467·5·UK ....•... 52 44 46 1,073 798 817 27 BR 82.5 KVx 30·G156-6-9K ....... .. 55 49 47 960 790 911 24 TS 80.0 KVx 30·G156-9·3K .. ... . • .. 51 46 50 943 1,118 603 28 BR 85.0 KVx 30·G200-1·2K ......... 52 43 46 877 811 728 28 BR 80.0 KVx 30·G200·1·3K ...... , .. 51 45 46 885 716 1,175 23 BR 60.0 KVx 30·G246-2·5K ......•.. 53 46 45 752 834 423 25 BR 87.5 KVx 30·G172·1·6K ......•.. 51 46 45 1,031 681 616 30 WR 72.5 KVx 30·G194·2·1K ......... 54 47 48 806 799 670 29 WR 75.0 Check varieties: TVu2027 ........... ... , .. 70 73 55 0 64 0 29 WR 90.0 SUVITA·2 ................ 50 46 45 706 772 691 20 BR 0 KN·1 .... .. ...... ....... . 49 44 44 806 505 636 14 TS 0 TVx3236 ...... .. . .... .... 50 45 440 710 797 920 U CR 0 Trial mean ....... , ....... 53 46 47 789 787 518 C.V .• % ........................ 4 8 4 24 24 42 Note: W = white. B = brown, R = rough, T = tan, S = smooth and C = cream. RDAI = days after infestation. 88 Grain Legumes Table 36. Performance ofbruchid resistant cowpea ditions. Maruca testulalis and pod sucking bugs were lines in UTA international yield trial 3 at controlled with selective insecticides that had no Loumbila, Upper Volta,1983 effect on thrips. Days Seed The population of thrips in racemes did not differ to 50% Yield, 100-seed color and significantly between test cultivars, contrary to the Cultivar flowering kg/ha weight, g textureU results obtained in 1982, when TVu 1509 had signi­ IT 8ID-985 __ ..... __ ... 53 2,557 23 WR ficantly fewer thrips than TVx 3236 and the suscep­ IT 8ID-988 . __ ...•..... 52 2,197 25 WR tible checks. TVu 1509 and TVx 3236 had significantly IT 8ID-994 ___ ...... __ . 54 2,301 24 WR fewer thrips than KN-l, but there was no difference IT 8ID-1007 __ ........ . 39 1,980 13 rS between TVu 2870 and Ife Brown (Table 39). TVx 3236 IT 8ID-I020 ....... __ .. 42 1,977 14 rS had the highest yield, but there were no significant IT 8ID-1032 .... __ .... . 41 1,861 19 rS differences between the resistant lines. IT 81D-I064 ........ __ . 40 2,217 20 rS New elite materials that have shown reduced IT 8ID-1137 . ____ ..... . 39 1,821 21 WR damage by thrips at Ibadan were planted in an IT 8ID-1157 ......•.... 44 1,785 18 BS Local check ......•.... 34 1,547 11 BS unreplicated trial in a farmer's field near Kamboinse to see how they respond to thrips in Upper Volta. Trial mean . .......... . 44 2,024 Maruca bugs were controlled with Bacillus thur­ LSD (5%) ..... __ .... . . 1 404 ingiensis and pod sucking bugs with endosulfan. C.V.,% .............. . 2 14 TVu 6863 and TVu 7376 had fewer thrips in the aW = white, R = rough, r = red, S = smooth and B = brown. racemes and flowers than the standard thrips resist­ ant variety, TVx 3236, and the susceptible checks. striga sick plot. The segregation pattern was at TVu 4544 and TVu 4548 were the top yielders, despite variance with results reported in the 1982 UTA their higher thrips population, indicating that they Annual Report. So, the study will be repeated next may ha ve some thrips tolerance. year with a more refined screening technique_- V.D. Aggarwal and N. Muleba Testing for Maruca Resistance Lines that showed some resistance to Maruca testu­ Entomology lalis in 1981 and 1982 were tested again this year. On-farm Evaluation of Cow peas Flower thrips and pod sucking bugs were controlled with two applications of monocrotophos, one at the A trial consisting ofTVu 1509, TVu 2870 and TVx 3236 raceme initiation stage a'nd another at the pod for­ (which have shown resistance to flower thrips), and mation stage_ Because of its early maturity, TVu 946 two susceptible checks, KN-l and Ife Brown, was was planted twice, once with the other varieties and conducted in a farmer's field near Kamboinse, Upper again 10 days later. The second planting ofTVu 946 is Volta, to determine the extent to which resistant not included in this discussion because it escaped varieties will suppress thrips under farmers' con- maruca infestation. Table 37. Performance of aphid resistant cowpea lines in Upper Volta, 1983 Yield, kg/ha l00-seed Seed color Cultivar Farako-Ba Kamboinse Pobre weight, g and texture8 KVx 145-5-1. ....... . . • . .. . ......•.. .. .. ......... 1,006 1,657 741 15 BR KVx 145-99-1. .... . . ____ ..• . . . . __ .. ... ______ •.... 1,244 1,627 831 12 BS KVx 145-27-4 __ ... • .. : •.... _. . __ .•.. • . .. . . __ •...• 743 1,244 993 17 BS KVx 145-34-1. .... • ...• . . • ..... ..•. ......... . ... . 885 1,175 1,160 14 BS KVx 165-28-3. __ ............................ _ ... _ 639 1,597 851 13 BS KVx 165-39-1. .... .... _. .........•............... 760 1,331 846 13 BS KVx 146-13-3 .. _ .............•...•......... '.' ... . 672 1,671 957 17 BR KVx 146-14-3 .........•...•..........•........... 576 1,298 889 15 BR KVx 146-12-1. ........•...•..•...•...•........... 793 1,450 1,188 19 BS KVx 146-21-3 ......... ....•..........•..... . .... . 593 1,060 1,333 18 BS KVx 146-27-4 ............. . ...•.. .... . . ..•... . .. . 689 1,721 995 11 WR KVx 146-53-2 ......... . . .. ......... .. . . . .. __ .... . 772 1,440 1,151 18 BS Check varieties: TVx 6484-51BI-K . ............ •... ....... . ...•.. . 305 333 157 17 WR SUVITA-2 ........... . ... . ...•...•...•.......... 856 1,236 1,450 20 BR KN-l ...................•.......•.......... • ... 480 1,288 763 14 TS TVx3236 ....... . .... _ ....... . .. .•.... ,. ........ . 902 1,116 1,144 11 CR Trial mean .. .................................. . 687 1,136 853 C.V.,% ....................................... . 25 29 25 aW = white, B = brown. R = rough, S = smooth, C = cream and T = tan. Grain Legumes 89 TVx 3236 had the fewest larvae in flowers and KN-l Table 38. Performance oflines in a regional cowpea the most. Neither variety, however, was significantly striga trial at Kamboinse, Upper Volta, 1983 different from Kamboinse Local, TVu 946 and VITA-5. Days to The percentage of infested pods was significantly Days first Percent lower in Kamboinse Local than in any other cultivar. to 50% striga striga Yield, The greatest seed damage was observed in the suscep­ Line flowering emergence emergence kg/ha tible check KN-I. This year no difference was found KVx 30-141-lG ..... 45 128 1.0 1,469 between the performance of TVu 946 and that of KVx 30-166-3G ..... 44 171" 0 1,408 Kamboinse Local, whereas they differed significantly KVx 30-183-3G ... . . 44 171a 0 1,567 in 1982. KVx 30-199-4G ..... 46 35 11.0 1,397 Although Kamb(jinse Local has some resistance to KVx30-312-3G ..... 44 35 7.7 1,289 maruca, it had 67% pod infestation by Spodoptera KVx 30-323-1G ..... 46 36 10.3 1,266 littoralis and appears highly susceptible to this KVx 30-403-lG ..... 44 126 2.7 1,247 species. Grain yield was significantly higher in Checks: TVx 3236 than in VITA-5 and SUVITA-2 and lowest Mougne ......... . 40 30 87.3 826 in Kamboinse Local. Drought at flowering reduced TN 88-63 .......... 41 30 82.3 1,322 yields, affecting KN-I, SUVITA-2, VITA-5 and 58-57 ......... . ... 42 128 1.0 1,229 Kamboinse Local severely.-Y.S. Rathore SUVlTA-2 ........ 43 171a 0 1,486 Trial mean ........ 45 91 22.2 1,212 Cultural Control of Thrips LSD (5%) ......... 2 57.6 17.4 370 This experiment has been conducted twice before to C.V.,% ........... 2 37 19 determine the effect of interc ropping on thrips popu­ aStriga did not emerge; this figure is the number of days from lation and grain yield. Intercropping seemed to planting to 31 December. provide no protection from thrips, and the yield results were inconclusive. In those experiments Table 39. Thrips numbers and cowpea yield in a insects other than thrips were controlled with selec­ farmer's field at Sakoula, Upper Volta, 1983 tive insecticides. The trial was carried out again this Thrips Thrips year with no pest protection and minimum pro­ Cultivar per racemea per Howerh Yield, kg/ha tection. For minimum protection two applications of insecticide were made, one of decamethrin at the Ife Brown. . . . . . .. .. . 27.48 101.32 412.34 KN-l ............... 22.94 121.10 359.46 raceme initiation stage and another of endosulfan at TVu 1509. . . . . . . . . . . . 24.62 76.40 647.00 the pod formation stage_ Monocropped cowpeas had a TVu 2870. . . . . . . . . . . . 22.60 97.92 587.44 plant density of 66,666 per hectare, and intercropped TVx 3236... ... . . . . . . 19.06 75.28 729.56 cowpeas had two densities: 33,333 cowpea and 26,666 sorghum plants per hectare (DI) and 50,000 cowpea Mean ......... ,. . . . . 23.36 94.40 547.16 LSD (5%) . . . . . . . . . . . n.s. 18.57 245.54 and 40,000 sorghum plants per hectare (D2). C.V.,% ........... .. 29.93 As one might expect, more thrips were found in the racemes of unprotected plants than in the protected 8.Total of eight samples. bTotal of six samples. ones. But there was no significant difference in thrips and maruca counts in flowers, suggesting a rapid Table 40. Reaction of cowpea cultivars to thrips and buildup of the thrips population between sprays. Nor maruca in a sorghum/cowpea intercropping was there a difference in thrips counts in racemes trial at Kamboinse, Upper Volta, 1983 between the two varieties, although KN-1 had more Thrips Thrips Maruca thrips and maruca in the flowers (Table 40). Thrips Cultivar perracemea per ftowerb per ftowerc counts in racemes are most important because that is TVx 3236 . . . . . . . . . . . . . 8.94 25.31 1.14 where they do the greatest damage. KN-1... . . . . . . . . . . . . . . 10.38 36.04 1.72 Between monocropped and intercropped cowpeas, no significant difference was observed in thrips in the Note: The effect of cultivar was significant for all varieties. !lTotal of eight samples. bTotal of seven samples. CTotal of six racemes. Fewer thrips were found in the flowers ofD2 samples. intercropped cowpeas than in monocropped cowpeas. The reason fewer were recorded in D2 may have been that the high plant density made them less con­ Treated plots had significantly more flowers than centrated. There was no significant difference in the untreated ones, and monocropped cowpeas that were population of thrips between the D1 intercropped sprayed produced more flowers than either ofthe two cowpeas and monocropped cowpeas, confirming the intercropping systems, which did not differ signi­ results of the past two years. The populations of pod ficantly from each other. With spraying the three sucking bugs were significantly higher in mono­ cropping systems produced about the same number of cropped than in intercropped plots, regardless of the flowers. plant density. We do not know, however, whether Although yields were generally low this year, the populations were actually reduced or simply insecticide spraying significantly increased the yield redistributed. of both cultivars in all cropping systems (Table 41). 90 Grain Legumes Only the yield of TV x 3236 increased significantly in Number of adults trapped both intercropping systems with no protection. The 35,---------------------------------------, yield difference between sprayed and unsprayed TVx 3236 in the D2 intercropping system was not signi· 30 ficant. The results suggest that TVx 3236 will perform reasonably well when intercropped with sorghum. 25 Intercropping appears to lessen the insect pest pressure on cowpeas. This and the partial resistance 20 of TV x 3236 to flower thrips probably account for its superior performance. KVu·69 gave the maximum grain yield (381 kg/h). Among the extra early varieties, IT 82E·9 (191.2 kg/h), IT 8E·16 (148.4) and IT 8E·18 (154.1) produced reason· able yields.- Y.S. Rathore and N. Muleba Insect Surveys Field and light·trap observations made in the last two years have shown that late planted and late maturing Figure 5. Numbers of S. littoralis in a blacklight trap, varieties suffer more from Spodoptera littoralis than Kamboinse, Upper Volta,1983. early planted, early maturing ones. To confirm these results, a blacklight trap was operated all year to SUVITA·2 (1,230.8) and TN 88·63 (1,202.1) gave signi· monitor adult populations ofthe insect. The resuits of ficantly higher yields than the other lines. the last two years have shown that the insect is At Kamboinse IAR·48 gave the best yield, but most present year·round and most active from mid·August other varieties yielded reasonably well compared to to the end of December. the local check. The results from the two locations The results for 1983, shown in Figure 5, indicate indicate that among the improved materials that the pest was active from January to March and SUVITA-2 gave maximum yields that were not signi· during the last half ofthe year. As suspected, its most ficantly different from those of TN 88-63, IAR·48 and active period was August to December, during which TVx 3236.-Y.S. Rathore at least three generations were completed. Regional Trials Agronomy The objectives of SAFGRAD's agronomy research Nine elite cowpea lines that had performed well during the past three years at different semiarid are to identify problems in cowpea production and locations were selected for evaluation' under mini· develop new production technologies for achieving mum insecticide protection in Niger, Senegal, maximum economic yields in the African semiarid Gambia, Togo, Benin and Upper Volta. Two in· zone, a vast area that includes 25 countries. secticide applications were made, one of decamethrin at the raceme initiation stage and another of en· Maize/Cowpea Relay Cropping dosulfan at the pod formation stage. At the time of Research on maize/cowpea relay cropping is intended this writing, results were available only from Niger to help farmers make better use of scarce moisture and Upper Volta (Table 42). According to data from and inputs by obtaining a fuJI yield of maize and Niger, the local check, TN 5·78 (1,413.3 kg/h), cowpeas on the same land in the same growing season. An experiment was conducted at Farako·Ba in the northern Guinea savanna to evaluate cowpea Table 41. Cowpea yield in sorghl,lm/cowpea inter­ cropping, Kamboinse, Upper Volta, 1983 cuitivars of two plant types (photoperiod sensitive and· insensitive) in a relay cropping system with Treatment TVx 3236 KN·l maize. Maize cultivar SAFITA·2 (90 days to maturity) Monocropped cowpeas kg/ha was planted on 30 June at 0.75·m row spacing with No spraying . .... ......... . .... . 14 g 2g 0.25 m between hills in each row. Maize plants Two sprayings .. ............... . 893 a 343 bc received NPK at planting and N one month after Intercrop Dl a planting during the rapid growth stage of maize. No spraying . ............ . .. ... . 165 ef 39fg Two sprayings ......... .. .. . ... . 468b 242 cde Seven cowpea cultivars, of which four (Kaya Local, Intercrop D2b Logofrousso Local, Ouahigouya Local and lAR 1696) No spraying . .................. . 198 de 36fg are photoperiod sensitive and three (KN·1, TVx 3236 Two sprayings .. ............... . 334 bcd .. 274 cde and VITA·5) are insensitive, were planted at two dates, 29 July and 6 September, in solid rows alternat· Note: Means followed by the same letter are not significantly different from each other at the 5% probability level. ing with maize rows. The spacing was 0.75 m between bPlant density of cowpeas was 33,333 and that of sorghum 26,666. rows and 0.20 m between hills in each row. Cowpeas Plant density of cowpeas was 50,000 and that of sorghum 40,000. were not fertilized but were sprayed twice during the Grain Legumes 91 growing season. The experiment had a split plot between maize cultivars; the average maize yield was design, with cowpea cultivars as main treatments and reduced by 12%, compared to relay cropping with plJlnting dates as subtreatments, and was replicated TVx 3236, a significant difference. The yield decrease fdurtimes. can be attributed to overcrowding under drought Cowpea cultivars, planting dates and their in· conditions. Drought may also have reduced the teraction had no significant effect on physiological growth duration of SAFITA·102 and IRAT·178. and vegetative traits of maize. Cowpea planting date Cowpea grain yield was highly significantly affec· did have a significant effect on maize yield, however. ted by maize cultivars, cowpea cultivars and the With cowpeas planted on 29 July, maize yielded 3,559 interaction between maize and cowpea cultivars and kgfha, compared to 3,886 kgfha with cowpeas planted significantly affected by row spacing. Because the on 6 September. This 8% yield reduction can be attri· rains ceased in mid·September, TVx 3236 (which was buted to early cessation of rains in mid·September, planted on 9 September) failed to set pods and pro· when maize was just entering the grain filling stage. duced no yield. Therefore, the effect of maize cui· The effects of moisture stress may have been worsened tivars on relay cropped cowpeas is judged here from by competition between maize and cowpeas planted the reaction ofthe cultivar Logofrousso LocaL Maize on 29 JUly. Since cowpeas planted on 6 September cultivars Jaune de Fo and IRAT·178 significantly were affected by drought, they competed only very depressed the yield of Logofrousso Local, as com· little with maize plants. pared to maize cultivar SAFITA·2. SAFITA·102 was Cowpea grain yield and time of flowering were intermediate between SAFITA·2 and Jaune de Fo. significantly affected by cowpea cultivars, planting Since SAFITA·2 was significantly different from the dates and their interaction (Table 43). Of the cui· other three cultivars in most physiological and tivars planted on 29' July, the ones that flowered morphological traits, its tendency to compete less. earlier gave high grain yields; late flowering cui· with cowpeas can be attributed to its earliness, short tivars and all cultivars planted on 6 September gave plant stature and lower leaf area index. However, negligible yields because of drought and foliar thrips damage. The advantage of photoperiod sensitive over insensitive cultivars in this cropping system, ob· Table 42. Grain yield of cowpeas under minimum served in 1981 and 1982, could not be verified this protection from insect pests, 1983 year. The results did clearly demonstrate, however, Yield, kg/ha the appropriateness of planting cowpeas under maize Kamboinse. Maradi, one month after maize planting. This practice has Cultivar Upper Volta Niger Mean only a minor effect on maize yield and enables cow· Bambey 21. . . . . . . . • . . . . . . . . . 609.6 105.9 357.8 peas to escape drought and give acceptable yields. LAR·48. . . . . . .• ... •. ........ 1,171.5 510.8 841.2 The findings of this year and 1982 also underline the IT 82E·60 . . . . . • . . . • . . . • . . . • . 579.9 166.7 373.3 importance of using early photoperiod sensitive KN·1........... . . ... . ... . .. 815.2 541.3 678.3 cowpeas in maize/cowpea relay cropping. Mougne . . . . . . . . . . . . . . • . . . . . 906.5 462.1 684.3 A second experiment tested the effects of maize 8UVITA·2 . . . . . . . . . . . . . . . . . . 758.7 1,230.8 994.8 cultivars, with different maturity periods and row TN 88·63. . . . . . . . . . . . . . . . . . . . 752.0 1,202.1 977.1 spacings, on the performance of relay·cropped cow· TVx 1999·01F.. . . . . . . . . . . . .• . 964.1 355.0 659.6 peas. Two early (90 days to maturity) maize cultivars, TVx 3236................... 920.1 664.6 792.4 SAFITA·2 and Jaune de Fo, and two medium matur· Local check" .. . . . .. . . .. . . . . . 205.9 1,413.3 809.6 ing (105 days to maturity) maize cultivars, SAFITA· Mean.... .. . ... . .. . . ...... . 768.4 665.3 716.8 102 and IRAT·178, were planted on 29June at Farako· LSD (5%). . . .. . . .. . . .. . . . . . . 177.7 251.3 Ba at two row spacings (0.75 X 0.25 m and 1 X 0.25 m). C.V., % ............. .. ... . . . 15.9 26.0 Two cowpea cultivars, Logofrousso Local (photo· BLocal checks were Kamboinse Local in Upper Volta and TN 5·78 period sensitive) and TVx 3236 (insensitive) were in Niger. planted under maize on 29 July and 9 September, respectively. The experiment had a split plot design, Table 43. Yield and flowering time of cowpeas in a with maize cultivars' as main treatments and a fac· maize/cowpea relay-cropping system, torial combination of two row spacings and two Farako-Ba, Upper Volta, 1983 cowpea cultivars as subtreatments, and was repli· Grain yield, Days to cated four times. The agronomic practices were as kg/ha 50% flowering described in the relay cropping experiment discussed 68ep- 68ep· above. Cultivar 29 July tember 29 July tember Maize yield was significantly affected only by Kaya Local .......... . 450 0 60 44 cowpea cultivars. SAFITA·102 yielded about as much Logofrousso Local . ... . 78 0 70 98 as SAFITA·2 and IRAT·178, but significantly more Ouahigouya Local. . .. . 451 0 53 45 than Jaune de Fo when relay cropped with TVx 3236 IAR 1696 ............ . 120 0 77 116 cowpeas. When maize was relay cropped with Logo· KN·l ............... . 365 0 45 62 frousso Local (which was planted one month after TVx 3236 .... . .... . .. . 510 0 45 62 VITA·5 .......... . ... . 489 0 45 45 maize), there were no significant differences in yield 92 Grain Legumes even though SAFITA-102 and ffiAT-178 flowered and probably do not justify the cost of spraying. matured at the same time and had about the same Management practices that keep maize yields at an height and leaf area index, they tended to depress the acceptable level, while reducing maize leaf area and yield of relay-cropped cowpeas to different degrees. plant population, would stimulate growth and yield This suggests that more factors than plant height and of relay cropped cowpeas and should be investigated. leaf area index (for instance, competition at the root system for soil moisture and plant nutrients) may be Date of Planting involved in competition between maize and cowpeas Experiments were conducted to determine the op­ during the overlap period in relay cropping. timum planting date and identify environmental The reduction of cowpea yield by tall, medium factors (drought, diseases and parasites other than in­ maturing maize cultivars in this experiment agrees sect pests) that limit cowpea yields. Six photoperiod with 1981 and 1982 results. From the experimental insensitive cultivars were tested at four planting results, it can be concluded that: (1) maize growers in dates at Farako-Ba (northern Guinea savanna) and the northern Guinea savanna will make better use of Kamboinse (Sudan savanna) and at three planting scarce available moisture and inputs by relay crop­ dates at Pobe/Djibo (Sahel savanna). Similar experi­ ping cow peas and maize; (2) the optimum time for ments involving five photoperiod sensitive cultivars planting cowpeas under maize is one month after and one insensitive one and four photoperiod sen­ maize planting; (3) delaying cowpea planting up to sitive and two insensitive cultivars were also estab­ one week after 50% maize silking may reduce cowpea lished at Farako-Ba and Kamboinse, respectively. yields, especially during years when rains end in The experimental design was a split plot, with plant­ early to mid-September; (4) high yielding, short, less ing dates as main treatments and cultivars as sub­ leafy early maturing maize cultivars appear more treatments The experiments were replicated four suitable for maize/cowpea relay cropping than tall , times. All plots received P 20 5 as superphosphate more leafy medium maturing ones. and two insecticide treatments, except the photo­ An experiment was carried out at Loumbila to period sensitive experiment at Kamboinse, which determine if it is possible to introduce maize/cowpea was sprayed three times. relay cropping in the Sudan savanna. Maize cultivar In the experiment at Pobe/Djibo, yields ofIT 82E-60 SAFITA-2 was planted on 24 June under three seed­ and KVu-55 (extra-early maturing varieties from bed preparation methods: (1) planting on flat beds; (2) southwestern Nigeria and southwestern Upper planting on flat beds, followed by earthing-up to make Volta, respectively) were not significantly affected by ridges and tying ridges three weeks after maize planting dates, and were the lowest of all cultivars at planting; and (3) planting on tied ridges. The spacing the first planting date (Table 44). The yield of the in maize was 0.75 m between rows and 0.25m between other cultivars tended to decrease with late planting, hills in each row. Two photoperiod sensitive cultivars losing an average of 14 kgfha for each day planting (Kamboinse Local Nair and Ouahigouya Local) and was delayed. TVx 3236, which was developed in two insensitive ones (TVx 3236 and SUVITA-2) were southwestern Nigeria, tended to yield better than planted in solid rows a lternating with maize rows on SUVITA-2, TN 88-63 and 5857, which come from dry 18 July and 23 August. The spacing was 0.75 m areas. between rows and 0.20 m between hills in rows. The At Kamboinse an average of20 kg/ha of grain was experimental design was a split plot, with a factorial lost by photoperiod insensitive cowpeas for each combination of three seedbed preparation methods as day planting was delayed. The extra-early cultivars main treatments and cowpea planting dates as sub­ IT 82E-70 and KVu-55 yielded about as much as KN-1 treatments. All agronomic practices were as described .at all planting dates except 27 JUly (Table 45). When in the preceding experiments, except that the crop planted after 4 July, those two cultivars dropped was sprayed three times to control insects. drastically in yield. The yield of TV x 3236 was Cowpea yield was significantly affected by seedbed significantly greater than that ofKN-1 at all planting preparation method and by time of cowpea planting. dates except 12 August. SUVITA-2 yielded poorly Cowpeas planted on 18 July yielded 198 kg/ha and when planted on the first two dates, which were more those planted on 23 August produced 47 kg/ha . rainy than the last two, but it was the only cultivar Planting on flat beds, followed by earthing up and whose yield did not drop nearly to zero at the last tying ridges three weeks after maize planting, and planting date. Its reaction to planting date illustrates planting on tied ridges did not differ significantly in its greater tolerance of dry than rainy conditions. their effect on cowpea yield, but both were signi­ Grain yields of the photoperiod sensitive cultivars ficantly better than planting on flat beds. The tend­ tested at Kamboinse are listed in Table 46. Compared ency of tied ridges to reduce cowpea yield, compared to the two photoperiod insensitive checks (SUVIT A-2 to planting on flat beds, followed by earthing up and and KN-1),the yield of the best photoperiod sensitive tying ridges, can be attributed to the large leaf area cultivar (Ouahigouya Local) was much lower than index this treatment caused in maize. Heavy shading that of the best insensitive cultivar (TVx 3236), by maize may have impeded the growth of cowpeas. especially at the first three planting dates (Tables 45 As observed in 1982, cowpea yields in maize/cowpea and 46). The yield of the other photoperiod sensitive relay cropping in the Sudan savanna a re low and cultivars was negligible at all planting dates. With Grain Legumes 93 Table 44. Yield and flowering time of cowpeas at Pobe/Djibo, Upper Volta, 1983 Time of flowering, JDs Grain yield, kg/ha 22 June 7 July 16 July Cultivar 22 June 7 July 16 July (173 JD) (188 JD) (197 JD) TVx 3236 . . . . . . .. .... . . .... .. .. .. . . .. . . .... .. .. . . . . . 992 779 707 234 236 239 SUVITA·2 . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 953 639 629 236 237 243 TN 88-63. . . . . . . . . .. .. . . . . . . . . . . . . . . . . . . . . . . .. . . .. . . . 782 566· 532 237 238 241 IT 82E·60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 295 321 237 237 238 5857 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 951 623 519 233 236 239 KVu·55. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 509 406 230 232 235 aJD = Julian days. Table 45. Performance of photoperiod insensitive cowpeas, Kamboinse, Upper Volta, 1983 Time of flowering, Julian days Grain yield, kg/ha 16 June 4 July 27 July 12 August Cultivar 16 June 4 July 27 July 12 August (167 JD) (185 JD) (208 JD) (224 JD) TVx 3236 . .... .•. . . . . ... ..•. . . . . . . . 1,760 1,641 1,293 347 207 228 253 269 SUVITA·2 . . . . . • . . . . . . . . . . . . . . . . . . . 993 1,071 993 479 212 230 255 269 TN88-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,957 1,451 1,1l3 460 209 228 252 265 KN·I.. ...... ........ .... . ......... 1,01l 1,190 8ll 0 210 229 251 267 IT 82E·70 . . . . . .... ... . . .. . . .. . .. . . . 1,199 1,374 197 166 204 223 245 264 . KVu·55 ......... ,. . .. . . . . . . .. . .. . . . 1,307 1,000 441 252 208 225 251 265 the exception of Ouahigouya Local, all photoperiod can be attributed to drought. Flowering of photo· sensitive cultivars tended to fail to flower. period sensitive cultivars was not impeded by drought, For three consecutive years Kaya Local, as was the case in the Sudan savanna. This could be Kamboinse Local Noir and Kamboinse Local Rouge related to the relatively low air temperature and good have failed to give acceptable yields. Although they water infiltration rate and water holding capacity of originated in the Sudan savanna, they are no longer the soil in the northern Guinea savanna. adapted to this climatic zone, in which the growing From these results and 1982 observations, it can be season has shortened by about one month in the last concluded that in the northern Guinea savanna: (1) 5 to 10 years. From these results it can be concluded planting cowpeas earlier than mid·July is a pre· that in this zone planting adapted photoperiod in· requisite to high yield; (2) medium maturing photo· sensitive cultivars before mid·July is conducive to period insensitive cultivars appear to be more adapted high yields and that planting insensitive cultivars than the very early ones, especially when planted after the end of July or planting long·duration photo· before mid·July; (3) some early maturing photoperiod period sensitive cultivars can drastically reduce sensitive cultivars such as buahigouya Local yield yields. about as well as improved insensitive ones, especially In general, yields at Farako·Ba were much lower when not planted very early in the growing season; this year than in previous years probably because the (4) planting late maturing photoperiod sensitive cui· rains ceased early, shortening the growing season tivars could reduce yields drastically, particularly in (Table 47). On the average, .photoperiod insensitive years when the rains end early; and (5) when planted cowpeas lost 11 kgjha grain for each day planting was early, photoperiod sensitive cowpeas provide better delayed. The early cultivars tended to yield less than ground cover than the nonsensitive ones. medium maturing cultivars at the first three planting dates. KN·l and TVx 1999·01F yielded significantly more than the other cultivars only when planted on Table 46. Grain yield of photoperiod sensitive 15 June. A long growing season enabled them to give cowpeas, Kamboinse, Upper Volta, 1983 several flushes of flowering, which permitted more Dates of planting than three harvests. Cultivar 16 June 4 July 27 July 12 Aug. The check photoperiod insensitive cultivar KN·l kg/ha yielded significantly more than any other cultivar Ouahigouya Local . . , 343 312 540 0 when planted on 15 June (Table 47). At the three Kaya Local. ........ 27 23 19 0 other planting dates, it yielded about as much as Kamboinse Local . Ouahigouya Local. The late flowering cultivars Nair ............ . 0 0 0 0 Logofrousso Local and IAR 1696 were among the SUVITA·2 .. ........ 554 454 881 0 lowest yielding cultivars at all planting dates. These Kamboinse Local results agree with 1982 observations for IAR 1696 but Rouge ........... . 56 51 40 0 Kn·l ............... 616 473 3 0 not for Logofrousso Local. The low yield of IAR 1696 94 Grain Legumes Striga Resistance Table 48. Density of striga in cow peas, Kamboinse, Upper Volta, 1983 A study on resistance to Striga gesnerioides was repeated this year to gather information on striga's Date of planting emergence date and density and to examine their Cultivar 21 June 18 July 12 Aug. Mean relation to cowpea yield. The study was conducted at plants per m2 Kamboinse in a strigll. sick plot that was artificially Ouahigouya Local. . . . . .. 31 10 11 17 reinfested at the time of planting. The experiment Kaya Local . . . . . . . . . . . .. 24 33 14 24 included six cowpea cultivars and three planting Kamboinse Local Noir. . .. 25 25 10 20 SUVITA·2 .............. 0 o 0 o dates in a split plot design, with planting dates as Kamboinse Local Rouge.. 32 21 12 22 main treatments and cowpea cultivars as subtreat· KN·l. .................. 30 31 12 24 ments. The agronomic practices were the same as for Mean .................. 24 20 10 18 the planting date experiments, except that cowpeas were sprayed with insecticide four times at 10·day intervals, beginning with floral bud initiation. SUVITA·2 yielded significantly more than any IITAjEMBRAPA Program other cultivar at the first two planting dates. When planted at the last date, it yielded as much as all Cowpeas are cultivated predominantly in the north­ culti vars, except Kaya Local and Kamboinse Local ern and northeastern regions of Brazil on an area of Noir. Since it was free of striga, its yield decline with about 1. 7 million ha. Annual production varies from delayed planting must reflect drought. All the other 400 to 500 thousand tons, with average yields of 500 cuitivars were equally infested by striga (Table 48), kg/ha. The major production constraints are variable and striga plants emerged at about the same time at rain distribution in the principal growing regions each planting date. Striga density increased with and damage by insect pests and diseases. The major early planting, and so did striga damage to flowering insect pests are cowpea curculia and leafhoppers, and and yield, except in the -case ofKN·1 (Table 49). the most important disease is cowpea severe mosaic KN·1 was the only photoperiod insensitive cultivar virus. Elite breeding lines and superior cowpea tested. Striga emerged slightly before this cuitivar cultivars have been introduced from UTA, and a flowered, so it sustained little flower damage. The hybridization program has begun. drastic decline in yield of KN·1 when planted on 18 July and 12 August can be attributed more to its high Variety Trials sensitivity to drought than to striga damage. The UTA/EMBRAPA (National Agricultural KN·1 failed to delay striga emergence as observed Research Organization of Brazil) cowpea breeding in 1982. Moreover, nane of the susceptible cultivars program consisted of 74 experiments divided among flowered before striga emergence. With these ex· 27 locations, including a preliminary trial, three ceptions the results agree in general with the 1982 advanced trials (divided by plant type) and two finding that cultivars flowering close to striga regional trials with brown and white seeded lines. emergence yield better than those flowering long after striga emergence. Thus, in the absence of resist· Preliminary yield trials. These trials consist of ance, early flowering may be critical in limiting F./Fs entries bulked from purification of F, seed striga damage.-N. Muleba multiplication plots. The materials are of acceptable seed quality and have resistance or tolerance to one or more virus diseases. A total of100 lines were tested Table 47. Grain yield of cowpeas, Farako.Ba, Upper in a simple lattice design. Pitiuba and Serido were in· Volta, 1983 cluded as local checks and CNC 0434 and CNCx 27·2E Date of planting as virus differentials. CNC 0434 is immune to the cowpea severe mosaic virus (CSMV), and CNCx 27·2E Cultivar 15 June 7 July 29 July 16 Aug. is highly resistant to several potyviruses. Most lines Photoperiod insensitive kg/ha outy ielded the best check line in Serra Talhada, TVx 3236.. .. ........ 1,266 1,054 1,116 362 Pernambuco state and Teresina Pi ani state; five TVx 1999-01 F...... .. 1,700 1,113 1,034 389 gave outstanding yields and had low virus scores: KN·l ............... 1,728 1,183 994 456 CNCx 24·015E, 24·016E, 87·5E, 87·1F. and 105·7F. Only Dembo Local . . . . . . . . 606 550 585 328 one line (CNCx 87·1F) had large seed, a low virus KVu·55. ... ...... . .. 776 729 569 465 score and good yield. IT 82E·7 0. . .. . . . .. .. . 839 668 779 375 Photoperiod sensitive Advanced yield trials. Each of the three ad· Ouahigouya Local. .. . 1,019 919 571 341 vanced yield trials had a triple latticeof25 lines. Trial KayaLocal. ... ... .. . 864 678 573 350 1 included prostrate lines, trial 2 semierect lines and Kamboinse Local Noir 724 855 558 383 trial 3 erect lines. The spacing between and within Logofrousso Local. . . . 455 569 576 298 rows was adjusted to the plant type. In advanced trial lAR 1696 . .. ....... . . 574 668 365 175 ' Mealybug and Green Spider Mites (ABCP). So far, Table 12. Disinfection of cassava cuttings planted in a $3.7 million has been received for 1983 from the glasshouse at IITA, 1983 Directorate for Technical Development and No. of H:umanitarian Aid (DCA) in Switzerland, the German Marta· Infesta· leaves Agency for Technical Cooperation (GTZ) and Treatment lity, % tion, % ( +S.E.) Austrian Federal Chancellery for Economic Vertical planting, no disinfec- Coordination and State-owned Enterprises tion (control) ...... . o 63.3 13.1 ± 0.9 (BKA WIKORD). The ABCP will need $30 million Horizontal planting. no over five years to cover about 50% of the cassava disinfection ............. . o 40.0 12.7 ± 0.9 growing areas in Africa with natural enemies of both Disinfection in freezer: pests. 90 minutes . ...... .. ...... . 3.3 31.0 11.3 ± 0.9 Although the total amount offunding required has 180 minutes . ...... , ...... . 6.7 14.3 10.0 ± 0.9 Disinfection with dimethoate, not yet come through, IITA has decided to go ahead 5minutes . .. ............ . o 3.3 9.6 ± 0.5 with the development of new technologies for the Disinfection in 52°C water: ABCP. Also, research and exploration for natural 15 minutes . .............. . 6.7 o 9.7 ± 0.7 enemies have been stepped up so that a ll the nec­ 30 minutes .. ............. . 50.0 o 7.0 ± 0.6 essary information and beneficial insects/mites will 60 minutes ... ..... .. ..... . 60.0 o 5.7 + 0.9 be available when the ABCP receives full financial support. The ABCP will be the largest biocontrol project methods, treating cuttings with hot water (52°C) for ever conducted and its prospects for success are very 15 minutes or possibly less gave superior results good. It could provide the impetus for introducing (Table 12). biological control into Mrica as a basic element of Vertical planting gave the same results in plant integrated pest management. growth as horizontal planting in all 10 varieties New rearing and release technologies are being tested. One variety (91934) produced significantly developed that will bring ABCP up to the highest pest more leaves with both planting methods. More va· control standards. The design and engineering work rieties will be tested under the more practical vertical are being done through cooperation between IITA planting system. biocontrol specialists and engineers from companies Survival and growth in a screen house of cassava in Austria and Italy. The aerial release tests are being planted vertically in 200·, 1,000- and 2,600·ml pots carried out by a Swiss firm under lITA supervision. (with and without fertilizer) were determined in a replicated experiment. Survival of the cuttings was 37, 55 and 89% for those with two, three and five Improvement ofthe Insectary nodes, respectively, or about 18% per node. The five· In the new insectary building, which became avail· node cuttings are therefore preferred. Growth was able early in 1983, the first rearings proved difficult, not influenced by fertilizer or cutting length. The and plant growth and survival in the glasshouses and surviving plants averaged 8.4,13.9 and 17.0 leaves per screenhouses were very poor during the rainy season. plant for the 200-, 1,000- and 2,600-ml pots, respec· The experiments described in the following sections tively. It was decided that for wooden insect rearing gave us a better understanding of plant production cages the intermediate pot size is preferable. When 60 heavily infested plants from the insectary and culture of pests and natural enemies and 1m· proved the output. were cut back to the cutting, they did not resprout and all died. Out of 60 lightly infested plants, 46.7% Cassava Plant Production resprouted, and all the uninfested plants survived a cutback. It thus appears that under present con­ During the rainy season, the mortality of cuttings ditions plants can be used only once. We hope that in taken from below and above the first branching of the future a means of reusing plants after cutback can healthy plants was 5 and 20% , respectively. Cuttings be found so as to save planting material. from CM-infested plants had mortalities of 20 and Certain types of soil are unsuitable for cassava 55%, respectively (for 40 plants, infested versus plant production. In especially rich forest soil with a non infested, X2 = 8.10*). Growth of the surviving pH of 7.8 and a high Ca content (19.4 ME/ lOO g), plants was unaffected by their history. survival of cassava was very poor and root develop­ Disinfesting cuttings with dimethoate, as is com· ment weak. Survival and growth were good in sandy monly done, proved unsatisfactory for clean culture soil with a pH of 6.1 and Ca content of 5.2 ME/lOO g. of cassava in a large scale insectary. Out of 30 Transplanting from unsuitable soil to suitable soil cuttings artificially infested with CM crawlers, 90% improved plant growth. Hydroponic culture has of the surviving plants were infested if planted in a several advantages over cassava production in pots vertical position, compared to 40% planted in a with soil : it permits control of nutrition, is cleaner horizontal position. Vertical planting after disinfes· and easier to manage on a large scale, and reduces tation with dimethoate yielded 46.2% infested plants. labor costs. Pilot studies were carried out to de· In a second experiment with two other disinfestation termine the nutritional requirements and optimum 116 Roots and Tubers environmental conditions for cassava grown in nu­ ergence from an egg mass at 27°C started on day seven trient solutions. and lasted to day nine. Under these conditions 90% of In the first experiment, cuttings were placed in all crawlers survived unfed for two days and at 8°C for plastic-covered bottles with a nutrient solution five days. No surfaces, plastic or Teflon, could be (Murashige and Skoog plant salt mixture) diluted by found that would keep crawlers from escaping. a factor of two. The treatments were: aerating the solution, aerating and adding CO2 , and no aeration. Parasitoid-Predator Cultures At fluctuating temperatures (27° to 35°C) and 5,600 The following species have been mass multiplied: lux, the plants started to develop shoots the day after four coccinellid predators, Hyperaspis notata, H. planting and grew rapidly_ The CO 2 concentration ?jucunda, Hyperaspis sp., Diomus sp. (=Scymnus); proved to be too high, however, and all these shoots one neuropteran, the hemerobiid Sympherobius sp.; died after five to seven days. There was no mortality and one parasitoid, the encyrtid Epidinocarsis in the other treatments, and aeration had a positive (=Apoanagyrus) lopezi. We have also received the effect on plant growth. last few specimens of an undescribed encyrtid through In another experiment conducted in a glasshouse CIBC, but these have not reproduced. Nor has the under better lighting (6,000 to 40,000 lux), plants grew coccinellid Nephus sp. In the new insectary, rearing vigorously; after four weeks the plants grown in two of parasitoid and predators succeeded only after different aerated nutrient solutions had an average of dehumidifiers were installed during the rainy season; 9.8 leaves and 2.09 g of dry weight per shoot, compared increased ventilation assured sufficient air exchange. to only 2.9 leaves per plant and 0.41 g of dry weight in Since in the plant and mealybug rearing units the soil-grown test plants. Aeration of the nutrient infestations of the CGM have sometimes threatened solution increased the mean dry weight by two and a the health ofthe plants, the influence of the acaricide half times. In the nutrient solution developed by Kelthane on the CM and E. lopezi was evaluated. In Farno, Asher and Edwards (1979), plants had greater August three replications of 10 small CM and CGM longevity than in the Murashige and Skoog solution . infested plants were treated with 1.2 mIl l and 0.6 mil l Mealybug Culture of Kelthane and with water only. Mortality of CM was assessed after 48 hours. Ten female E. lopezi were Infestation of cassava plants with mealybug craw lers added to each treatment cage, and adult CM were is difficult during the rainy season but relatively easy removed to prevent reproduction . Mummies and in the dry season. In an experiment conducted in adults of E. lopezi were counted after one generation November and December, groups of plants of equal of the wasp. The results indicate that the Kelthane size (seven leaves per plant) in two sizes of pots (200 treatment, which kills CGM, has no effect on the CM and 1,000 ml) were infested with two CM egg masses and only a negligible one on the parasitoid (Table 13)_ per plant. Half the pots were irrigated every 1.5 days, Kelthane pretreatments can therefore be considered the other half every 3 days, and on half of the plants safe, especially if the waiting period is longer than the tip was removed. The resulting eight treatments two days after treatment. According to the literature, (with 12 replications) placed the plants under dif­ however, direct treatment of adult encyrtids with ferent degrees of stress. After five weeks the green Kelthane is harmful. and dry leaves and the mealybugs on 20 leaves from Special difficulties were encountered in rearing each treatment were counted. The mean number of E. lopezi, especially in cages with only moderate CM for each plant group was calculated. The mean mealybug densities, where the culture died out. Three . number of CM per plant group for one treatment (Y) observations, supported by experimental evidence, was then correlated with the number of green leaves led to a solution ofthis problem. (Xl) and the percentage of dry leaves (X2 as arc sine Adult parasitoids were observed in a screen house v p). The following regression equations were found: on plants in randomly lJlixed trays, four with heavily Y = 327-2.176 Xl (t = 2.24 n.s_), and Y = 197 + infested, yellowish plants, and five with vigorously 2.725 X2 (.t = 3.20*). These equations suggest that growing, very lightly infested plants. The males were under the same atmospheric conditions the same swarming around the tips of the plants or sitting on number of mealybug eggs gave a higher total CM the tips of lea ves, and the females were mainly sitting infestation in the next generation, the more stressed or searching on the stems in the interior of the the plants were (that is, the fewer leaves they pro­ canopy. All wasps were removed with aspirators and duced and the more dry leaves they had). This finding sexed. On the heavily infested plants , the sex ratio confirms the observed difference in mealybug de­ was 1.4% females (N = 282), on the green plants velopment between the rainy and dry seasons_ 22.4% (N = 76), and on the screen of the room 79.2% In studies on the emergence and behavior of CM (N = 24). Thus, females seem to prefer green plants crawlers, it was found that emergence is very much and to disperse more easily than males. reduced during the dark period. If undisturbed, 50% In preliminary experiments it was found that CM of all crawlers emerging on a given day did so within survives better on isolated fleshy leaves of waterleaf six hours after the onset of light. If the egg masses (Talinum triangulare) than ·on those of cassava, were shaken, emergence was faster and 50% of the which curl up and dry out fast_ To observe oviposition crawlers emerged within four hours. Crawler em- and record oviposition success, one female E. lopezi Roots and Tubers 117 Table 13. Influence of the acaricide Kelthane on cassava mealybug and its parasitoid E.lopezi Number of individuals Percent mortality 0.6 mlfl 1.2 mlfl 0.6 mlfl 1.2 mlfl Sta~e Control Kelthane Kelthane Control Kelthane Kelthane Cassava mealybug First . ................ 204 221 164 4.4 5.4 6.7 Second . .............. 136 154 186 2.2 0.6 1.6 Third ................ 93 64 123 l.l 1.6 0 Fourth (removed) ...... 25 46 91 8.0 0 0 E.lopezi . ............... 91 74 60 Percent parasitism ...... 17.4 14.4 11.3 Note: These figures are sums and means for 10 plants. and 10 young eM females were added to each of 16 x within the first 10 days. Within that period 48.4% of 10 petri dishes with a waterleaf. The petri dishes were the parasitoids from the upper half of the plants stored at cool temperatures and on the next day emerged in the first five days and 51.6% in the second placed at the different light and temperature con· five days. From the lower plant parts, 58.2% emerged ditions shown in Figure 2. (Temperatures were mea· in the first five days (X2 = 55.7*). The predominance sured inside the petri dish.) The wasps were removed of olfler mummies (from which adults emerged soon at 0, 1, 6 and 24 hours after the start of the experiment after the start of the experiment) on the lower plant and observed for 1 hour. As many as eight ovi· parts may be explained by migration of parasitized positions per hour were observed, but the mean was mealybugs from the upper plant parts. This depletes less than one per hour. Although numerous unpara· the older mummies, which are to emerge in the first sitized eM were available, the wasps made repeated five days, from the top of the plant. Mealybugs that oviposition attempts on the same host. But no mummy were stung by E. lopezi shortly before the plants were was ever found in the field or laboratory where more than one E. lopezi adult emerged. Percent unexplained mortality Observations of host feeding showed that females, usually after having stung their host, turned around 50r-------------------------~ and fed on it. After five days, dead, dried out eM, o 800 lux living eM (including ones that were parasitized but 30.5°C still moving) and mummies were counted, and 15 days later all emerged E. ·lopezi were identified. The percentage of parasitism was calculated on the basis 40 o 21,500 lux of living, unparasitized eM on the fifth day and 36.5°C emerged parasites. Figure 2 shows clearly that the "unexplained" mortality of the eM, which is attri· buted to host feeding, is linked to the oviposition 30 activity of the wasp. The ratio of host feeding mor· 6,500 lux tality to mortality through parasite reproduction 34.2°C varies with light and temperature and should be further investigated but most often is above 1: 1. The eM mortality of more than two for each egg laid 20 explains why cultures cannot be maintained at low host densities and must be considered in interpreting field data. It was observed that E. lopezi emerged from dis· carded pots and dry sticks from which all green plant 10 parts had been removed. To find out more about the distribution of the mummies, 10 heavily infested plants from the rearing cages were cut in pieces and placed in the emergence cages. The distribution of parasitoids emerging from the different parts was as OL------'--------'--------'---------' follows: 6.2% from the tops with folded leaves, 32.0% o 10 20 30 from the upper leaves, 29.1% from the lower leaves, Percent parasitism 8.8% from the upper and 11.4% from the lower half of Figure 2. Host feeding by Epidinocarsis lopezi. Depending the stems, 6.8% from the sticks that originally served on the light and temperature, unexplained mortality in­ as planting material, and 5.7% from the pots (100% = creases with the activity of the parasitoid, expressed as 6,719 parasitoids or 672 wasps per plant). percent parasitism. Each point represents about 100 cas­ Ninety·two percent of the parasitoids emerged sava mealybugs exposed to 10 females for 0, 1~, 6, and 24 h. 118 Roots and Tubers cut had to stay on their severed substrate and could of 100 km. It had covered Oyo and Ogun states and not migrate. spread into K wara and Lagos states. Sampling in The results of this experiment indicate that care December 1983 indicated that E. lopezi was present in must be taken not to lose paras ito ids in the insectary most CM infested fields within its previous distri­ and that in fie ld data based on sampling of bunch tops bution and had spread further through Ondo State parasitoids may be systematically u nderestimated.­ into Bendel State in the East. P. Neuenschwander, T. Haug, H.R. Herren and E. From samples collected, the following indigenous Madojemu parasitoids and predators were reared. They were identified by staff members of the Commonwealth Natural Enemy Releases Institute of Entomology (Z. Bou~ek, S. Brooks, K.M. Harris,J.S. Noyes, B.R. SubbaRao, T.G. Vazirani and Dispersal of Epidinocarsis lopezi M.R. Wilson). E. lopezi was released in November 1982 on Texagri • Anagyrus pseudocoeei Girault- A few specimens farm near Abeokuta, Nigeria, became established were found, but they may have come from stray and spread through several fields. Further spread was Phenacoccus madeirensis. Up to five specimens were investigated by taking samples of cassava tips from reared from a s ingle mummy of P. madeirensis on !ITA and farmers' varieties at 100-m intervals through­ Malvaeeae. In the laboratory reproduction on P. out the farm. Since E.lopezi was found virtually every manihoti was exceedingly poor. 100 m, samples were taken during. March 1983 at 10- • Prochiloneurus insolitus (Alam)- This hyper­ km intervals on roads leading in all directions. As parasitoid was commonly reared from P. manihoti shown in Figure 3, the wasp was discovered over an and P. madeirensis mummies. On P. manihoti it was area with a diameter of over 200 km, reac hing from always solitary, except once when a pair was reared the Guinea savanna in the north to the rain forest in from the same mummy. the south. The data suggest that the wasp had colon­ • Chartocerus ?subaeneus (Forster) and Chartocerus ized virtually every CM infested field within a radius sp.-These two signiphorids were commpnly reared .."Kishi 8 ~ KWARA STATE o 00o · .... IIorin o NIGERIA \, OYO STATE o lseYin ) IIe "'Oyo .s .\ .h.a. • . ... Ikere Iba.d.a.n. . •• ~ . . "'fe 00 ~Akure ........ . ONDO STATE Farm-l>----- .,0 a '!iOndo release I'" I'<\)eO\<.u site o~ .... , • GUN 0 ~ eeo.o IOOkm oo TATE "'Shagamu 0 • LAGOS STATE • • Parasites found L agos o Not found 9adagri Figure 3. Spread of E. iopezi five or six months after release at Abeokuta, Nigeria, in November 1982. Roots and Tubers 119 from mummies of P. manihoti as well as P. ma­ Number of nalural enemies per gram dry weight deirensis. Up to three specimens of these hyper· parasitoids were found on the same E. lopezi. Cry welCjlhl .": • Mariettajauensis (Howard)-This aphelinid hyper­ % Bunch toP\ ~ 5 ,;-------\. 1.0':: ",0 parasitoid was rare. In one case it was reared from a !. ~ P. manihoti mummy, together with one C. subaeneus. E . " " i"i , c • Tetrastichus ~ sp.-This eulophid was reared on , is ~ several occasions from P. manihoti mummies. <; c .," A lopez! • c Inspection of the mummies suggests that it is a •0 ~ " ~ hyperparasitoid. c 02 •0 • Hyperaspis ?senegalensis Mulsant- This is the most abundant coccinellid predator of the CM; it is o ...J "0 also found on P. madeirensis. At low CM densities, it 5r--------------------------, has been observed feeding on nectar on the weed Coccinellids Euphorbia sp. • Hyperaspis pumila Mulsant-This is the second most abundant predator. • Exochomus ?troberti Mulsant-This large coccinel­ lid occurs mainly at high CM populations. • Scymnus sp., Nephus sp.-Several of these small o coccinellids were found locally. Some are very abun­ 5-50 dant on P. madeirensis. 45 11 14 19 • Brinckochrysa sp.-A widespread but never abun­ Figure 4. Number of E. lopezi and coccinellids per gram dry dant cbrysopid predator. weight of cassava tips in relation to distance from a release • Nimboa sp.-An uncommon coniopterygid site near Abeokuta, Nigeria, together with mean dry weight per tip and mean percent bunch tops in the field. predator. IITA = improved variety and FV = farmers' variety. • Dicrodiplosis manihoti Harris-This cecidomyiid Median, lower and upper quartiles are indicated. predator sometimes was very abundant on heavily infested tips. All existing records of this species are from P. manihoti. This is the first record of the species available later and the hyperparasitoid populations in Nigeria, but it is known also in Senegal and Congo could not yet build up. To this hyperparasitism, that Republic. of Chartocerus sp., which showed no relation to host • Campylomma sp.- This predaceous mirid was density, can be added, assuming that on the average found only occasionally. two hyperparasitoids emerge from one mummy. The • Oeocoris amabilis Stal-An infrequent lygaeid combined degree of hyperparasitism then becomes predator. 50.6% (based on an estimated 1,000 mummies) at Coccinellid paras ito ids that reduce the efficiency Texagri farm and 26.1% (1 ,026 mummies) in the other of the coccinellid predators were sometimes fairly fields. But despite this reduction in the reproductive common: potential of E. lopezi, the wasp seemed to be efficient • Metastenus sp.-Up to eight specimens of this and can be credited with the reduction in size and pteromalid were reared from one H. senegalensis. incidence of bunch tops at Texagri farm, compared to • Homalotylus africanus Timberlake-This and an­ the situation in outlying fields. other encyrtid were reared from H. senegalensis. The indigenous coccinellids were more abundant The number of parasitoids and predators per gram in fields far away from the release site and where the dry weight of the bunch tops collected in March 1983 incidence of bunch tops was higher and the in· is given in Figure 4. Within a radius of 100 km, E. dividual bunch tops were larger than at Texagri farm lopezi was homoge·neously distributed, and no differ­ (Figure 4). But if coccinellid density is expressed per ence in population density between IIT A and farmers' gram bunch top dry weight, no difference between the varieties was found. There was, however, a marked various areas is observed .- P. Neuenschwander, difference in the degree of hyperparasitism between K.M. Lema and H.R. Herren the Texagri farm (all varieties) and fields outside the direct release area, where E. lopezi had spread only later. The density of P. insolitus, expressed as wasps Impact of E. iopezi on the eM per gram dry weight of bunch tops (Y), was linearly After the parasitoid Epidinocarsis lopezi and predator linked to that of its host E. lopezi (Xl for Texagri farm Diomus sp. were released at the Texagri Farm near and X, for the other fields). The regression equations Abeokuta, Nigeria, in November 1982, studies were are Y = 0.22 + 0.702XI (t .= 8.39*) and Y = 0.14 + conducted to assess their impact on the CM. Thirty 0.202X, (t = 5.76*). From the slopes of these straight samples from the upper 10 cm of the shoot were lines, the mean percentage hyperparasitism by P. collected biweekly from a control and a release field insolitus alone is calculated as 4l.3% on Texagri farm 2 km apart, and the populations of the pest and and 16.8% in the other fields, where the host became beneficial insects were assessed. 120 Roots and Tubers The results, shown in Figure 5, indicate that the assessing these mortality factors are still under eM population in the release field was lower than investigation, but it should soon be possible to make that in the control field: At the peak population, more exact estimates.- K.M. Lema, H.R. Herren and which was reached in February in the control field, 96 P. Neuenschwander eM (all stages except eggs) were counted per shoot. In the release field, the peak population of 49 eM per shoot occurred in early March. Indigenous Predators Only two individuals of Diomus sp. were found in Several species of indigenous natural enemies have the field early in the dry season, and no others were adopted the eM as an alternate prey in many African recovered during the sampling period. E. lopezi countries infested by this pest. Entomophagous coc­ became established and was observed throughout the cinellids constitute by far the most important group sampling period, including the rainy season. The of indigenous natural enemies. Although it is be­ highest population density for E. lopezi was 8.9 lieved that local predators alone cannot solve the eM mummies per shoot, and the highest rate of para­ problem, they do constitute a mortality factor of the sitization was 30%. Indigenous coccinellid predators, pest and'should be evaluated sothe impact of released the most important group of local natural enemies, exotic beneficial insects can be estimated accurately. were observed in the release and control fields from During the rainy season, when the eM is very scarce February to May in relatively low numbers (Figure in the field, entomophagous coccinellids are not 5). observed on cassava, and it is suspected that weeds The difference in mealybug population between the serve as an alternative noninsect food source. control and release fields is undoubtedly due to the E. Observations were made of weeds within and around lopezi parasitoids, although there is still some doubt cassava fields in Abeokuta , Nigeria. When coccinel­ about the exact percentage of mortality they have lids were found feeding on the nectaries of a weed, an inflicted. The mortality factors may be parasitization identification number was given to the weed, and (assessed by the number of mummies in the samples) leaves, stem portions, and flowers and/or fruits were and host feeding (in which the adult parasitoid kills collected according to herbarium procedures. Plant the host by sucking its hemolymph). Methods for species were then sent to the IITA Weed Service for identification. Populations of predatory coccinellids were moni­ tored on the two most common weeds and a culti vated Average nlJmber of cassava mealybugs per shoot vegetable_ Five plants of each species were observed 100 every other week, and species of entomophagous coccinellids and the numbers of individuals were recorded. Early results ofthis experiment indicated that five species of weeds and one cultivated vegetable were 80 serving as noninsect food sources for local predators during the rainy season. The weed species were Cassia tora, C. mimosoides, Hibiscus asper, Tephrosia Control field f/exuosa and Urena lobata. One variety of the culti­ vated okra H. esculentus was also observed harboring , 60 a large number of predatory coccinellids_ The combined population levels of entomophagous coccinellids on H. asper, U. lobata and H. esculentus are shown in Figure 6. The coccinellid species re­ corded are as follows in order of importance: 40 Hyperaspis ?senegalensis, Cheilomenes lunata, H. pumila, Cheilomenes sp. and Exochomus ?troberti. No immature coccinellids were observed on weeds dur­ ing the sampling period_ To survive when their normal prey is not available, adult indigenous coccinellids feed on nectar from 20 glands located on the leaves and on flowers of some plant species. These coccinellids do not become phytophagous per se during the rainy season, and they do not chew any plant part or suck any sap from the plants. During this period entomophagous coc­ o 9 18 21 30 21 7 ~3 17 31 144 181 cinellids disperse widely, and their reproductive Nov Dec Jan Feb March Apr May June Oct capacity is drastically reduced since this alternative Figure 5. Population density of cassava mealybug in release food source offers energy but is not adequate for egg and control fields, Abeokuta, Nigeria. production.- K.M. Lema ' Roots and Tubers 121 Average numoer per plant Insect Production and Release Tunnel Insect Production System 24 After investigating several options for the mass­ production system, !ITA has accepted designs pro­ duced by an Italian coropany (Fig. 7). Consideration 20 is being given to constructing a model 10 to 15 m long to test some of the assumptions of the design. The Tunnel Insect Production System (TIPS) has two sec­ 16 tions, the phytotron and entomotron. In the phytotron cassava plants suitable for CM and CGM production are grown under optimal conditions in hydroponic solution; plants 50 cm tall can be grown in less than 21 12 days. In the entomotron, which is hermetically sealed from the phytotron, the CM, CGM and their natural enemies are multiplied and collected for packaging. The two sections,linked with a special lock system to 8 avoid any upstream insect movement, consist of eight sealed tunnels 120 m long and 6 m wide. The system will produce an estimated 15 million beneficial in­ 4 sects and/or mites per day on 5,000 plants. Up to six different species can be produced simultaneously in adjacent tunnels as well as the CM and CGM needed to maintain them. The modular design of two four­ oL-~ __L -__- L~~ __~ ~~~~ 1917 418 24/8 719 4/10 19110 2/11 tunnel units would give the necessary flexibility in Sampling date the construction phase. In addition, the climate Figure 6. Population of indigenous coccinellid predators on control and general design of the system would aU; --: two weeds and a cultivated vegetable, Abeokuta, Nigeria, it to be used for other plants and insects, if this 1983. becomes necessary in a later phase of the project. Exploration for Natural Enemies Automatic Insect Packaging System In 1983 the exploration activities of our team in the Beneficial insects and predatory mites produced in Americas were split between Paraguay and Brazil. the rearing unit will be transferred to the packaging Two trips were also made to Bolivia, where CM room and kept aHow temperature for processing in . natural enemies were found in 1981 and 1982. A new the Automatic Insect Packaging System (AlPS). This base for the exploration team in Brazil was estab­ system allows up to four species of beneficiannsects/ lished in August at a research station in Dourados, mites to be packaged simultaneously in the same Mato Grosso do SuI. From this station the whole of release unit. Figure 8 shows the AlPS model now Brazil will be explored systematically for natural under construction. Insects and mites, kept cool in a enemies of CM and CGM over the next three years. CO2 atmosphere, are vibrated from the storage We expect to locate many more natural enemy species containers into small funnels. The numbers of insects suited to the various ecological zones in which they and mites are estimated volumetrically by an over­ will be released in Africa. flow system before they are inserted into the cells of In Brazil a mealybug culture has been established the release cassettes. Each cassette contains 361 to rear the newly discovered natural enemies , and cells, each of which is fitted with a wick drenched cassava has been planted for field ecology studies. So with sugar water as a food source, and can hold up to far, four trips have been made in the state of Mato 1,500 natural enemies, depending on the species. The Grosso do Sui, and P. manihoti has been found in very loaded cassettes are kept in containers that have low numbers at two locations, Campostre and Porto their own cooling system and are used to store the Murtinho. No new natural enemy species have been beneficial insects and mites in an airplane. One AlPS found. To increase the likelihood of finding more unit has an estimated packaging capacity of 1.5 to 2.0 natural species, trap plants (potted cassava plants million insects or mites per hour. infested with mealybugs in the lab) will be placed at several locations and brought back to the base Automatic Insect Release System laboratory for examination. Local extension services and the mass media have Aerial release of CM and CGM natural enemies is been contacted to get information from farmers and efficient, fast and thorough, ensuring that not only extension officers about the mealybug and green farmers along major roads (where ground releases are spider mites.- B. Loehr, H.R. Herren and A.M. easily made), but those in remote areas, will benefit Varela fully from the ABCP. To counter the CM and CGM 122 Roots and Tubers with the hest and most up-to-date means avai lahl", making cOllt inuOll !-i release possible. totally new aerial release methods are being de­ The stoppers are expelled from the cell by air veloped. Figure 9shows the Automatic Insect Release pressure of 0.5 bar from the aircraft engines and are System (AmS), which is now being tested in Nigeria. then accelerated in two phases to reach the outside The AmS has already undergone intensive wind air stream 'at a speed of about 200 km/h_ The aircraft tunnel testing in Austria, where it was developed. will fly at a speed of250 to 330 km/h. The wind tunnel For the current testing in Nigeria and later use in the and flight tests have shown that these accelerations ABCP, the system has been fitted into a twin turbo­ and air currents do not harm the natural enemies. prop Beech 18 Volpar aircraft. Over a six-month The aircraft is equipped with an Omega trac flying period, different release patterns (varying in altitude, guidance system that will a llow it to fly swath widths speed, swath width, release frequency and natural of as little as 500 m without ground flags. enemies species) and different stopper types will be In planning the release flights, information about tested in three areas of southern and eastern Nigeria cassa va growing areas will be gathered from aerial or and in other countries with CM problems in different satellite photographs and land-use maps. This pro­ ecological zones. The AmS, which is controlled by a cedure should ensure that the natural enemies are microprocessor, can release up to one stopper per used efficiently and not released in non-target areas. second and can store two cassettes simultaneously, -H.R. Herren and D.J. Nadel Figure 7. Tunnel Insect Produc­ tion System (TIPS). Figure 8. Automatic Insect Packaging System (AlPS). Figure 9. Automatic Insect Release System (AIRS). Roots and Tubers 123 Zaire National Cassava Table 14. Performance of cassava clones in a final yield trial at Mankewa, M'VU8Zi, first Program season, 1982-83 Fresh lITA is providing technical assistance to the Zaire yield, Resistance to: 8 Branch· National Cassava Program (PRONAM), whose objec­ Clone t/ha CMD CBB CGM ing ht.b ti ves are to develop improved varieties and tech­ 40230/4 .. . .... 22.7 1.8 2.2 2.5 2.0 nology, make these available to farmers, and provide 4(2)0060/3 ........ 21.2 2.5 2.0 3.5 2.0 in-service and degree-level training to Zairean re­ 50467/12 ......... 21.0 2.0 2.0 4.0 1.0 search and extension workers. Substantial progress 60639 ........... . 20.5 2.3 2.0 3.0 1.0 was made during 1983 toward these objectives. 30555/5 .... . ... .. 20.0 2.0 2.0 3.0 2.0 02864 (improved standard) .. .. .. 19.9 2.5 2.0 3.5 2.8 Genetic Improvement 61665/4 .......... 18.3 2.0 2.0 2.5 2.0 D 128 ............ 17.1 2.5 2.0 2.5 1.5 Variety Release 30010/1 .......... 16.9 2.0 2.0 4.0 1.3 CA 5052/4 ..... . .. 16.1 2.0 2.2 2.0 3.0 The results of multilocational variety trials over the Mpelolongi (local) 15.8 2.7 2.0 3.0 3.0 past several years were reviewed by a variety release M Col 1265 ....... 19.8 2.8 2.0 3.0 1.0 committee in late 1982. It was decided that variety LSD (5%) .. . . .... 4.3 30085/28, because of its superior and stable yield ~esistance to cassava mosaic disease (CMD) bacterial blight performance, good level of resistance to cassava (CBB), and green spider mite (CGM) was rated on a 1 to 5 scaIe, bacterial blight, and the acceptability of prepared where 1 = no damage and 5 = severe damage. root and leaf products to consumers, should be b1 = less than 1 m, 2 = about 1 m and 3 = morethan 1 m. proposed for release to Zaire's Department of Agriculture. The variety was officially released in Table 15. Performance of cassava varieties in January 1983 and, because of its disease resistance, multilocational yie ld trials, Bandundu has been named "Kinuani," which in the Kikongo Region, Zaire, 1982-83 language me·ans "fighter." Kinuani has been multi­ Fresh root yield, t/ha plied on a large scale for distribution and is being Variety Five plateau sites Two valley sites demonstrated to farmers . F 100. . . . . . .... .. .. ... .. 12.0 17.8 F 150. . . . . . . . . . . . . . . . . . . 9.4 13.7 Hybridization and Testing F156......... . .. ... .. .. 9.1 13.3 Local. . . . . . .. .. .. .. .. . . 4.0 13.0 At M'Vuazi, 30,445 se·eds from 50 families were sown in a seedling nursery. Twenty·one percent germinated and were successfully established. Based on disease and pest resistance and agronomic characteristics; but limited valley soils. The yields of the three most 754 plants were selected for further evaluation. Five promising clones are given in Table 15. They appear hundred and sixty clones selected from the 1981- 82 to be well adapted to the plateau soils, where they seedling nursery were evaluated for disease and pest gave yields two to three times higher than those of the resistance, root yield, root conformation and branch­ local variety. In the valley sites, the yield ofF100 was ing habit. Of the 92 clones selected for further testing, 37% greater than that of the local variety. Great many showed resistance to cassava bacterial blight interest is being shown by development agencies and and cassava mosaic disease. Thirty·one clones were farmers of the region in these varieties.- W. W. selected from 107 lines tested in preliminary yield Fieb ig trials. Yields of the selected clones ranged from 18.1 to 40.8 t /ha, compared to an average of 14.6 t /ha for Demonstration of Improved Varieties the local check. Of the 43 lines evaluated in advanced To demonstrate the performance of improved va­ yield trials, nine were selected. The highest yield rieties to farmers , PRONAM collaborates with a obtained was 23.8 t /ha, compared to 16.1 t/ha for the number of agencies that are able to reach farmers local check. The performance of 10 clones tested in a with new technology, including the extension service final yield trial is shown in Table 14. Five clones gave of the Department of Agriculture, the National significantly higher yields than the local check.­ Fertilizer Program, the Agricultural Production T.P. Singh and N.M. Mahungu Project of Mvanza-Ngungu, the Integrated Rural Performance of Promising Clones Development Project of Luala in Luozi, Oxfam, the Salvation Army and several church groups. With Several varieties selected at the Kiyaka station were these agencies demonstration plots were established tested in a multilocational yield trial at seven sites in at about 150 locations in the Bas Zaire and Bandundu the Bandundu Region. Trials were conducted both on regions. These demonstrations confirmed the super­ the poor sandy soils of the plateau, which are very ior performance of the improved varieties. The reo extensive in the region, and on the more productive suIts of 23 demonstrations conducted with the 124 1I00is and Tubers Fresh root yield (t Ihe 1 mealybug. E. lopezi was recovered there in June 1983, 30 and by September parasitized mealybugs (mummies) were abundant on leaves (an average of21 mummies per leaf in a sample of 14 leaves from heavily infested LSD (5%1 plants). Even so, the mealybug was not brought under satisfactory control, almost certainly because the parasitoid's effectiveness was reduced by three ~ Local species of native hyperparasitoids, Proehiloneurus • Kinuoni insolitus, Chartoeerus sp. and Paehyneuron sp. The 20 total percentage of hyperparasitism by these species reached 86.7 in a sample of 136 mummies on five lea ves in late September. Diomus sp. was not recovered at Kinshasa. Neither E. lopezi nor Diomus sp. was recovered at any of the 1982 release sites in Bas Zaire possibly because mealybug populations remained at generally very low levels well into the 1983 dry season.-R.D. Hennessey 10 New Releases of Natural Enemies In July 1983 2,250 individuals of Diomus sp. were released at three sites in the far southern part of Zaire's Shaba Region. A few individuals of E. lopezi and Hyperaspis notala also were released at one of the sites. In September only a single individual of Diomus sp. was recovered, and no individuals ofthe other two species were recovered. Nine hundred Diomus sp. and o a few Sympherobius sp. were released in Kinshasa in 0-0-0 50-50-50 100-100-100 July. In September a single adult of Diomus sp. was Fertilizer rote ( kg Iho N-F'205-K20l found; no Sympherobius sp. were recovered.-R.D. Figure 10. Yield (mean for 23 locations) of the improved Hennessey and K.M. Lema cassava variety Kinuani and a local variety at three fertilizer rates, Bas Zaire, 1982--83. Survey for Cassava Mealybug Field observations by PRONAM personnel and National Fertilizer Program in Bas Zaire are shown cooperators in 1983 provided a fuller picture of the in Figure 10. The recently released variety Kinuani status of the cassava mealybug in Zaire. The known significantly outy ielded the local variety at all fer­ distribution of the mealybug in the major cassava tility levels and was more responsive to fertilizer.­ growing regions of Zaire is shown in Figure 11. So far, S.J. Pandey and W. W. Fiebig all reports of the mealybug have come from localities with a dry season at least 90 days long. At the Multiplication and Distribution of prevailing temperatures, 90 days is sufficient for Improved Varieties about 2! mealybug generations. No relation was seen between the number of mealybug generations expec· Approximately 200,000 m of planting material of the ted in a typical year (2! to 4, depending on the newly released variety Kinuani were distributed in locality) and the distribution or severity of the pest. Bas Zaire this year. To meet the rising demand for this Accumulated observations of mealybug damage in variety, rapid propagation techniques are being used. various vegetation zones indicate that potential New plantings of Kinuani covering 47 hectares were damage by the mealybug is not equally great through­ made in November and December by PRONAM and out its range. Damage is chronic and severe in the collaborating agencies. In the Bandundu Region, clear Zambian forest zone of Shaba. During dry years approximately 100,000 m of cuttings of improved damage has been severe and widespread in the wood­ varieties were distributed to agricultural develop­ ed Guinean savanna and Zambian steppe of Bas Zaire ment projects and farmers during the year.-S.J. and Bandundu. Pandey and W. W. Fiebig Plant Resistance to Cassava Mealybug Entomology Previous studies at PRONAM/M'Vuazi have de­ Follow-up on Release'sofNatural Enemies monstrated that populations ofthe cassava mealybug increase more slowly ori clone 70453 than on suscep­ In the 1982 dry season, a sIngle release of Diomus sp. tible varieties. That the clone is also tolerant to the and Epidinoearsis lopezi was made at Kinshasa in a mealybug was demonstrated this year by the follow­ field of wild manioc heavily infested with cassava ing methods. Thirty-six cuttings of 70453 and 24' of Roots and Tubers 125 Average number of centimeters per shoot Dry season 30r---------------------~--~ =90 d/yr 70453 Uninfested 20 Infested weekly 10 OLM~~ __L -~ ___ L_ _~ __L _~ ___ W Co'I4 .................... UA 14 La &A. 50 Ji) throughout the soil profile is DAP ... .. .. . . . .... .. ...... .. 30 3,814 6,209 1,842 among the major reasons for the low available water· 60 4,104 5,943 3,161 holding capacity. These soil factors, together with P APR·50 .............. . ..... 30 3,585 6,390 5,489 . intense rainfall and frequent dry spells during the 60 3,613 7,609 4,909 cropping season in the subhumid and bimodal rain­ SSP. . ..... ... .. .. ... ... ..... 30 4,226 6,376 4,098 fall regions, often lead to rapid changes in the 60 4,077 6,737 4,711 nutrient and water supply to the crop. It is essential LSD (5%) ... . . ..... . . .... ... . 726 1,056 1,621 for us to gain a better understanding of the nutrient and water relationships in these soils to improve the fertilizer and water use efficiency of crops. In cooperation with Buntehof Agricultural Table 15. Comparison ofCeM and urea as N source s Research Station, West Germany, and the German for maize, lITA , 1983 Agency for Technical Cooperation (GTZ), two experi· N source, Grain yield, ments are being carried out at lIT A : one on an Alfisol 120 kg N/ha Time of application kg/ha (Oxic Paleustalf, Egbeda Series), with maize planted CCM .... .... Two weeks before planting 3.48 in the first season (April to July) and cowpeas in the Urea. . . . . . . .. Two split applications 3.33 second season (August to November) and a second Urea. . ....... At planting 2.86 experiment on a coarse-textured Entisol (Psammentic Ustorthent, Apomu Series) with maize LSD (5%) .. ............... ... . ... ........... .. 0.54 and cowpeas grown in rotation in a seven~year·old C.V.,% . ....... ... ... ............•. . .. . . . ..... 7.8 leucaena alley cropping system. Soil solution probes Farming Systems 155 and tensiometers were installed in the cropped fields lent to the percentage of storage pores (0.2 to 50 I' in at 10-cm depth intervals to monitor changes in soil diameter). In the Egbeda soil, the transmission pores moisture content and nutrient concentration in soil constitute about 34 % of the total soil volume, and the solution over time. available water content 10 to l6%. The high pro­ Although the .r,!-iny season started late this year, portion of transmission pores explains why there was rainfall was well distributed during the crucial neither water lodging nor impeded aeration in either months of the. growing season (May to June). The field after heavy rain. This relationship may not hold grain yield of maize was 4.3 t /ha in the unfertilized plots and 5.2 t/ha in fertilized plots, which received 120 kg N, 60 kg P, 100 kg K and 30 kg Mg/ha. Soil solution analyses showed that the bulk of the nitrate and potassium was found in the top 30 cm of c .<: 10 ~ the soil and that their concentration had dropped to :::: ."~ ~" / very low levels by the middle of the growing season, ~ !/ o 15 May when only 60% of the final dry matter yield had been J!! -0 ~ .30May produced and grain filling had just begun (Fig. 18). 'V 8 June ,EThis suggests that, unless the crop can accumulate an ., 0 + ... 20 June excess of mineral nutrients in the early stages of (A) growth for redistribution in the later stages, ad­ ditional Nand K have to be supplied. The additional 0 Apr May June July Aug supply ofN and K are particularly necessary for soils 0 with a low exchangeable K pool, and the rate of mineralization of soil N is minimal toward the end of • the first cropping season. This is even more so when the period of low nutrient supply coincides with the period of low soil water content. Under these con· ditions the growth and yield of crops, such as maize and upland rice, that have high nutrient demand but shallow root systems can be severely limited. There was some downward movement of nitrates in the soil at midseason after 410 mm of rain (Fig. 18). The relatively slow rate of movement indicates that leaching of nitrate in the well-drained, newly cleared ( B) Alfisol may not be as rapid as cine would expect. Similar changes in N03-N and K were observed in the 100 Apomu soil, although the concentrations were much o 200 400 600 lower. NOrN in soil solulion (ppm) Changes in the soil moisture profile during the o r--------------, growing season are shown in Figure 19. In the Egbeda soil under maize monoculture, there was only one .....~ --r:Y'» moisture depletion zone above 50 cm. Water content in the subsoil horizons (at depths of 80 and 100 cm) remained relatively high throughout the growing seaSOD. E '-' In the second experiment, with maize in a leucaena :;; 50 alley cropping system, water extraction patterns in­ C.,. dicated no moisture 'competition between leucaena o and maize (Fig. 19). The tensiometer readings showed two separate zones of water depletion or uptake by the plant: the first, occurring at a depth of 0 to 40 cm, (C) was attributed to the root activity of maize, and the second (70 to 90 cm) was apparently the result of water use by leucaena. The water use of maize was 100 'a;ll------'-------'-----' o 100 200 lower in the Apomu soil than in the Egbeda soil K in soil solulion (ppm) because of late planting in the former. An important feature of these soils is their high Figure 18. Nitrate find potassium concentration in soil Kolution in nn Alfisol at various times during maize growth, proportion of macro- or transmission pores ( > 50 I' in IITA, 1983. (A) Growth curve of maize (the data points on diameter) and low available water-holding capacity. the curve indicate the stages at which the nutrient con­ In the Apomu soil, the transmission pores make up centrations were determined as a function of time); (B) approximately 40% of the total soil volume, and the nitrate concentration in soil planted to maize: and (C) available water content is 7 to 10°/." which is equiva- potnssium eonccntrntion in soil planted t.o maize. 156 Farming Sysl.ems after the same soil has been compacted under con­ Paleudult) are being studied at IITA's Onne sub· tinuous cultivation of annual crops with heavy station, which receives an average of 2,440 mm of equipment. rainfall annually. The study is a part of an lIT AI After a heavy rai n (50 mm in two hours), soil Netherla~ds cooperative project on nitrogen moisture tensions at: low as 20 to 30 millibar were utilization in the tropics. Twelve tension·drained recorded, but the cOl'l:esponding water content of the mono lith' lysimeters (80 em in diameter and 120 em Apomu soil was only 12 to 15% and that of the Egbeda deep) were installed. Maize was planted in the first soil 15 to 18%. This i "dicates that a large proportion growing season (March to July) and upland rice in of the transmission pores were sti ll air filled. the second season (July to November). The low water.holding capacity of the soil and the In the first season, four Iysimeters received I5N· rapid drainage of eX j~ess water through macropores labelled urea; four received unlabelled urea; two allow only a small po rt of rainwater to be used by the bare Iysimeters received 15N·labelled urea; and two crop. Adequate groHth and yield therefore depend more bare lysimeters received no fertilizer. The maize upon frequent soil water recharge. Two possible crop rec~ived urea at a rate of 135 kg N per ha in two means of increasing nutrient and water use efficiency split applications. Lime was incorporated at a rate of are to carefully adjust the timing of fertilizer appli· I t CaC03 /ha in the upper 10 em of the soil two weeks cation and to select. or breed for deep rooting crop before planting. Other nutrients, including P, K, Mg, species or varieti es that can use subsoil moisture Sand Zn , were applied at the recommended rates. more effectively during dry periods.- H. Grimme, During the second season, urea was applied to A.S.R.JuoandB.7'. Kang upland rice at the rate of 90 kg N/ha in two split applications. The number of cropped and bare Iysi· Leaching of Nitrnte Under High Rainfall meters was the same as for maize, but the Iysimeters Nitrate leaching patterns in an Ultisol (Typic that received unlabelled and ISN·labelled urea were interchanged. Leachates were collected at regular intervals, and N0 3·N, NH,·N and other nutrient cations and anions were analyzed. Deplh (em) Nitrate leaching patterns of the cropped and bare 0,------ lysimeters are shown in Figure 20. For both seasons only one nitrate peak was obtained , suggesting that , Maize Monoeullu,e ~\ ~ on Iy the first season N appli cation was leached out or moved below the Iysimeter's maximum depth of 120 ~~A9'If~iSO~~I' ~E~"=::.~ed~o~s~e,~,~e s~~~~~= ==,oA~~~~ em. Since the rain had virtually stopped in December, the second season application was expected to drain 50 out during the next rainy season, which starts in March 1984. In the bare, unfertilized Iysimeter, a ! e 27 June substantial amount of mineralized N, which formed o 5 July during the onset of the rainy season (nitrogen Rush), I::. 8 July a lso leached out readily (Fig. 20). The leaching .13 July (A) patterns . of NH 4·N are not given because the con· 100 centration of NH,N in the leachates was very low Or-----· throughout the year. The cumulative curves of total mineral N (NO, + NH.) in the leachates are given in Figure 21. Leaching .of applied N was apparently complete by the end of the rains in December after a tota l of600 I of Alley Cropping ( Maize/ Leucaena ) leachate had been collected. The amount of mineral· En1isol, Apomu Series ized N that was leached out of the lysimeter under 50 bare fallow (7.58 g N/lysimeter) exceeded the total N uptake by the first season maize (4.09 g N/lysimeter). Adjusting the planting date based on predictions of (8) the rate of downward movement of nitrate would 100 J/ ,/ increase the efficiency with which crops use mineral­ ized N. o 200 400 600 Based on nitrogen leaching data from the fertilized SQil water suction (mbl and unfertilized bare lysimeters, it was estimated Figure 19. Patterns ill soil water suction under two crop­ that about 61% of the added N (135 kg N/ha) was ping systems between l'ainstorms, IITA, 1983. High suction leached below 120 em by the end of the rainy season. indicates low soil water content. (A) Under maize monocul­ This suggests that the remaining 40% of the added N ture water extraction occurred only from the top 50 em of (urea) w.as either lost through volati lization in the soi l. (B) Two separate maxima developed in a field under limed soil or retained in the soil in the form of NH. +, leucaena/maize alley cropping. NO, or both. Farming Systems 157 and aeration, bulk density, water infiltration , crop establishment and yield . " ....... -.... ......... I Water infiltra tion decreased with increased til­ ~~ I ~~ lage, reaching a maximum in the no-till plots, parti­ Bore,l,If'O opplied '- , \. 30 'f CrOPp'd" , cularly those covered with crop residue mulch (Table , IIfell opplied \ :I 16). Removal ofthe residues from no-till plots lowered .. , \ \ infiltration by about 18% . Chiselling done in 1982 had no effects on infiltration in 1983. Infiltration was 20 , I '''',.~\ slowest in ridged plots because a clay film formed at the furrow bottom. Regardless of the tillage method, ~eor., water infiltration was about the same in all plots • no lerl l"zer where the surface soil had been mechanically dis· 10 I / / . turbed. There were no significant differences in bulk #,' ./ densities (Table 16). No·till treatments had high infiltration, despite relatively high bulk densities, o l\~...' ~-~-~-E-:-~~~~':---== __ ~ __ ~ __ -L_ _- L_ _- L_ _~ probably because earthworm and root channels pro· o 50 00 150 200 250 300 350 400 450 500 550 vided pore continuity. Cumulalive leochote volume (I) During a three-week drought; which occurred Figure 20. Leaching patterns of nitrate in monolith lysi­ immediately after the first season crop was seeded in meters under cropping and bare fallow, Onne, Nigeria. April, there were significant differences in soil tern· 1983. peratures among different tillage treatments. These were due to differences in soil moisture content, the The total N balance and the amount of N leached insula ting effect of crop residue mulch and the from the fertilizer source will be assessed when "N surface area exposed to insolation. analysis of plant and leachate samples has been One problem with tillage is that it leads to crusting completed.-Wong Ting Fook, A .B.M. van der Kruijs and A.S.R. Juo Torol mlnera' N In I,oenole (q) 14 Seedbed Preparation and Tillage 12 Effects of Tillage on Soil Physical Properties and Maize Production 10 A long· term experiment was begun in 1980 to in­ • vestigate the effects of seedbed preparation methods on soil physical properties and maize production. The 6 • seedbed preparation methods were no· tillage with and without crop residue mulch, no· tillage with 4 chiselling, plowing with and without residue mulch 2 and with ridging, plowing at the end of the rains, and rotovation. Fertilizer was applied to a ll treatments at oo - ••- ~~~~~,~~~~~~~~~~~~~~~ 50 100 150 200 250 3CX) 350 400 450 500 550 600 a rate of 100 kg N, 26 kg P and 30 kg K/ha. No-tillage CumulOhVf! leaChate volume (I 1 plots were sprayed with Paraquat at 5 l/ha five days Figure 21 . Cumulative leaching curves of mineral nitrogen before seeding. In 1983 the effects of various tillage (NO, - and NH, +) under cropping and bare fallow, Onne, methods were quantified in terms of soil temperature Nigeria, 1983. Table 16. Effect of tillage methods on soil physical properties, UTA , 1983 Accumulative Oxygen Soil temperature infiltration, cm/3h diffusion rate, Bulk density, g/cm' at5cm,OC Treatment 1981 1983 /lg /cm/min ot o 5 cm 5to IOcm 0800 1500 No·tillage with residue mulch ...... . 216 168 0.520 + 0.190 1.4 1.5 29.9 34.1 No·till with chiselling in 1982 . ...... . 120 80 1.6 1.5 28.9 34.9 Moldboard plowing followed by two harrowings . .......... . .. . ... . . . 177 68 0.254 + 0.138 1.6 1.5 29.6 42.1 Disc plowing ..................... . 155 71 0.359 + 0.150 1.4 1.4 29.4 42.7 No-till without residue mulch ....... . 168 138 0.339 + 0.179 1.4 1.6 29.3 37.9 Plowing at end of rains ... . ........ . 134 74 1.4 1.5 29.7 43.7 Plowing, harrowing with mulch ..... . 183 79 0.40!i + 0.Q78 1.4 1.5 30.5 37.3 Plowing, harrowing with ridges ..... . 87 59 1.6 1.5 28.3 43.9 LSD (5%) . . . . . . . . . . . . . . . . . . . . . . . .. n.s. 50 n.S. n.s. 0.8 1.4 158 Farming Systems Table 17. Effect of tillage methods on maize Soil Compaction and Seedbed performance, IITA,1983 Preparation Methods Emerg· Grain Straw ence, Plant ht. , cm A study was begun 'in 1982 on a gravelly Alfisol yield, yield, Treatment % 4WAp· lOWAP t /ha t /ha (Ibadan series) to determine the effects of mechanized farm operations (seeding, fertilizer and herbicide No·till with applications, and harvesting) on soil compaction and residue mulch .. 71 61 b 258 ab 4.4 a 4.4 ab No·till with root growth and yield of maize seeded after con­ chiselling ...... 84 75 a 254 ab 4.2a 4.2 ab ventional and no-t illage. The experiment had a split Moldb. plowing plot design with three replications. The two tillage and two treatments, as main plots, were split into subplots, harrowings . . . .. 77 58 b 267 a 3.7 a 5.5a with and without residue mulch. Disc plowing . .... 72 62b 263ab 4.6a 5.2ab The experiment was repeated in 1983. Soil bulk No·till without density, infiltration rate, root growth and yield were residue mulch .. 52 59b 224 bc 3.7 a 3.6ab measured periodically. During the second season, Plowing at end of after the rains ceased abruptly in October, drought rains . .... ..... 72 63 b 258ab 3.8a 4.5ab stress was assessed by monitoring hourly changes in Plowing, harrow· ing with mulch . 87 59b 264 ab 4.4 a 4.2ab the leaf water potential of maize. Plowing, harrow- By the end of the second crop in August, the bulk ing with ridges . . 15 40c 215 c 3.4 a 3.2 b density of the plot on which farm operations had been done manually was still low : 1.12 g/cm3 for the 0- to 5- Note: Means are grouped according to Duncan's Multiple Range Test at the 5% level. em layer and 1.37 g/cm 3 for the 5- to lO-cm layer. But "'WAP = weeks after planting. w here mechanized operations wer,~ practiced on no­ till plots, soil bulk density increased to 1.46 and 1.52 g/cm3 for the two layers. With cpnventional tillage the low bulk density observed immediately after and surface sealing of the soil. Plowed plots often plowing and seeding (1.11 and 1.35 g/cm3 ) increased to develop an impermeable crust that slows water and 1.47 g/cm 3 for the 0- to 5-cm layer and 1.48 g/cm3 for air movement through the soil profile. No·tillage with the 5- to lO·cm layer at harvest (Table 18). mulch prevents or reduces surface crusting and There were also differences in water infiltration facilitates movement of water and gases. As shown in among treatments. The least water infiltration was Table 16, the oxygen diffusion rate was lowest on a observed in plots on which farm operations were bare or ridged, plowed soil surface. completely mechanized and in those that were not Seed germination and crop establishment were mulched (Table 19). Consequently, those plots were affected by differences in soil temperature and mois­ also susceptible to accelerated soil erosion and lost as ture regime (Table 17). The ridged plots had the much as 12 to 26 tlha of soil during one cropping lowest germination. The no·tillage treatment with· season. out mulch suppressed maize emergence. A second The maize grain yield of the first and second crops seeding was necessary in some treatments with low was not significantly influenced by the degree of emergence. Crop vigor was also affected. As with crop mechanization; it was consistently greater in the emergence, plant growth four weeks after planting mulched than in the unmulched treatments. The . was lowest in ridged plots. Maize yields in those plots growth of the third consecutive maize crop was was 23% lower than on no· till or plowed, mulched significantly influenced by soil compaction resulting plots, but this difference was not significant. Mulches from mechanization (data not reported here). This appeared to increase yields slightly. Chiselling im­ crop suffered from severe drought stress, and the proved germination and early growth, but this did not plants in severely compacted (completely mechan­ result in better yields.-R. Lal ized) treatments were less vigorous and wilted earlier Table 18. Effects of seedbed preparation methods, mulching and mechanization on soil bulk density, IITA, 1983 January August Treatment Ot05cm 5to10cm Ot05cm 5to lOcm glcm' (±S.E.) No-till (manual) with mulch ... . . .................... . 1.15 ± 0.007 1.31 ± 0.02 1.12 ± 0.12 1.37 ± 0.09 No·till (manual) without mulch ............ .. .... , ... . 1.15 ± 0.08 1.33 ± 0.12 1.22 ± 0.06 1.31 ± 0.07 No·till (partially mechanized) with mulch ....... . . .. .. . 1.20 ± 0.06 1.21 ± 0.10 1.20 ± 0.03 1.34 ± 0.05 No·till (partially mechanized) without mulch , ..... .• ... 1.21 ± 0.10 1.13 ± 0.09 1.29 ± 0.04 1.48 ± 0.03 No-till (mechanized) with mulch .. .............. . .... . 1.30 ± 0.09 1.43 ± 0.05 1.46 ± 0.05 1.52 ± 0.03 No·till (mechanized) without mulch . ........... .. . , .. . 1.43 ± 0.05 1.49 ± 0.07 1.45 ± 0.05 1.49 ± 0.09 Conv. tillage (mechanized) with mulch ... .... . ... . . , .. . 1.11 ± 0.07 1.35 ± 0.07 1.47 ± 0.07 1.48 ± 0.07 Conv. tillage (mechanized) without mulch ... ... . .. . , .. . 1.39 ± 0.08 1.57 ± 0.04 1.27 ± 0.10 1.36 ± 0.10 Farming Systems 159 Table 19. Effects of tillage, mechanization and mulching on infiltration, soil erosion and maize y ield, UTA, 1983 [nfiltra· Soil ticn rate, erosion, Grain yield, tjha ,Treatment cm/h ( + S.E.) tlhalseason First crop Second crop No·till (manual) with mulch .... . ........... . 35.2 ± 13.6 o 7.2 4.6 No·till (manual) without mulch ........ ..... . 26.2 ± 18.3 4.8 6.0 3.7 No-till (partially mechanized) with mulch .... . 38.9 ± 7.2 o 6.4 4.3 No·till (partially mechanized) without mulch .. 43.1 ± 5.5 7.9 5.6 4.0 No·till (mechanized) with mulch ............. . 29.1 ± 23.4 4.1 6.7 4.1 No·till (mechanized) without mulch .......... . 16.0 ± 16.2 12.0 6.1 3.8 Cony. tillage (mechanized) with mulch ....... . 20.0 ± 12.3 4.8 7.1 4.9 Cony. tillage (mechanized) without mulch .... . 17.7 ± 15.2 26.1 5.8 4.6 than those on which farm operations were done Leaf water potential ( bars) manually. Furthermore, roots extended farther into 25.------------------------------. the soil of no·till treatments with mulch than in 9-10 NOV 1983 completely mechanized, conventionally tilled treat· ments (Fig. 22). These observations on root growth were corroborated by data on leaf·water potential 20 (Fig. 23). The plants in plowed plots had lower leaf water potential (more negative) than those in no·till mulched treatments where farm operations were 15 done manually.·-H. Franzen, R. Lal and W. Ehlers (University of Gottingen, West Germany) •• ~ Tillage and Nitrogen 10 In the African tropics, soil compaction can be a major /~"'-... .. Mechanized} no-till .... ,# ,"'- ..... problem in mechanized, partiCularly no·tillage, crop production on low·activity clay Alfisols, resulting 5 in poor crop establishment and lower yields. Hour of day 0'---'---'---'--'--'------'---:-''---'---'---'--'--'--' 7 9 II 13 15 19 21 23 3 5 7 Roof lenQlh density (cm/crn'l ) .----------,1.5 Figure 23. Diurnal fluctuations in leaf water potential of O · IDem maize in a plowed, un mulched. completely mechanized 2.5 o·rOcm ~ -1.0 treatment and in a no-till, mulched, partially mechanized Mecncnzed cony. till) treatment, !ITA, 1983. 2.0 " '-- 0.5 Conventional tillage can make good seedbeds on compacted soils but may increase erosion. Another :: [2: :£ alternative is the paraplow, which has rigid , slanting legs that loosen and lift, but do not turn, the soiL In breaking up compacted areas, the paraplow does not interfere with the protective cover of surface mulch. :1::;:-:=: ~ I t.""~ The para plow was tested on compacted upland <:J Alfisols in two trials carried out on a degraded I Egbeda soil (Oxic paleustalO at !ITA. The experiment had a split plot design with three replications. The 0.5l 20-3::..- ~'-eJ l 30·40em ~ first trial was started at the beginning of the rainy season on a plot that had been under mixed grass o I I ~ _____ ~i'~~~~~~-O~~~ fallow for several years. Maize was planted with a 0.5 l 30· 40em Il 40·5Qem I rolling injection planter, giving stands of 70% , 81% o , I • .... I ' • . 05l 40·50cm l and 90% in the no·till, paraplow and plowed plots, 50~60cm I respectively. Some replanting was done in the no·till g I • ,I • IS. plot, but it still had a lower stand. Supplementary irrigation was used during the early growth stages of o l 5o·SOem I l SO-70em I the crop. 0,' I I ! •. I! I • I [ o 5 7 9 II 13 0 5 7 9 II J3 As shown in Table 20, maize responded signi· Weeks after seeding ficantly to nitrogen. Tillage also had a significant Figure 22. Effect of tillage method, mulbhing and degree of effect on plant establishment and yield. The disc plow mechanization on root length density of maize, UTA, 1983. treatment gave the highest yield and no·till the 160 Farming Systems lowest. Yield differences caused by tillage were differences between the paraplow and disc were not highest with no N and the lowest N rates. In the signficant. The results show that the para plow may plowed and paraplow treatments, maize responded to have potential fot use on compacted soi ls. - B. T. N application up to 120 kglha but in the no·till plot Kang, C. Garman, M. Sulaemi and Koharuddin only to 30 kg/ha. In the second trial, conducted on a plot that had Tillage and Residue Management been planted to a cover crop of Mucuna utilis for more The effects of tillage and crop residue on crop pro­ than one season, maize was hand planted, and all duction were studied on an Alfisol (Oxic Paleustalf) treatments had good stands. The soil had an average at Mokwa in the savanna region of central Nigeria. bulk density of l.27 g/cc . As shown in Figure 24, The experiment had a randomized split plot design tillage and nitrogen application significantly affec­ with four replications. As reported in the 1982 Annual ted maize yield. The paraplow gave the highest yield and no-till the lowest, even at high N rates. Yield Report, mulching in the first year was partial, consist­ ing only of the residue from the short grass fallow in the field. Results of the trial for 1981 to 1983 are given in Table 20_E ffects of tillage and N rate on maize yield Tables 21 and 22. In 1981 plant establishment was in degraded soil that had been under mixed poor because of bird and rodent damage , so there were grass fallow, lITA , 1983 no significant differences between treatments. In 1982 N rate, kg/ha Tillage Paraplow No-till Mean and 1983, conventionally and manually tilled plots kg/ha produced significantly higher maize yields than the 0 ......... . .. . ... . 3,533 2,332 1,540 2,468 strip and no-tillage plots (Table 21). Yields of sor­ 30 ................ . 3,394 2,446 2,260 2,700 ghum under conventional tillage were higher than 60 ............ _. .. . 4,452 2,729 2,342 3,174 under other treatments in 1981, whereas in 1982 the 90 ................ . 3,867 2,807 2,442 3,039 strip tillage plots produced the highest sorghum yield 120 . . . . ...... .. .... . 4,255 3,270 2,392 3,306 and no-tillage the lowest. These results suggest that Mean ....... ... ,. ... . 3,900 2,717 2,193 appropriate tillage practices may be essential on LSD (5%): naturally compacted soils in the sub humid and semi­ Tillage means . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 765 arid regions to facilitate seed emergence and good Nitrogen rate means. . . . . . . . . . . . . . . . . . . . . . . . 623 crop establishment. The effects of crop residue on yields were incon­ sistent. During 1981 and 1982 in both maize and sorghum, yields were slightly higher where residues Maize grain yield ( t I he ) were burned than where mulch was applied or the residue removed. But in 1983 the mulched plots yielded more than those on which residue was burned Poroplow or removed (Table 22). In 1982 the very low yield of 6.0 I sorghum in mulched plots was due to Cercospora leaf disease, which was transmitted with the sorghum LS D {5%) ugh the program has had successes, it has not In.stitute's core resea.rch. Its objectives are to develop been wIthout problems. Among these are the difficult ehte ~ermplasmthat is suited to the diverse ecologies socioeconomic setting and poor transportation and of AfrIca and to ensure the flow of this germplasm into marketing facilities. For these reasons PRONAM national programs for testing and adaptation. will inevitably be a long-term project and even then The evaluation team's unanimous conclusion was that this project has made remarkable progress in ~illiead to a self-sustaining national program only If the government alters some of its agricultural meeting its objectives for each crop. It noted that a policies and practices. nUI?ber of ~ig~ yielding, disease and insect pest The review team recommended that PRONAM be reSIstant varIetles have been developed and are being tested in farmers' fields. The team further commented cont~n,!e~, p.referably as part of a broader multicrop, multldIscIplmary project. This recommendation has that the 20 technicians and 8 degree candidates who have received training under this project "represent al~eady bee~ acted upon, and in the future the proj ect wIll deal wIth the major annual crops grown in an important gain in human resources that can be rotation or association with cassava. In this new mobilized for the benefit of tropical Africa." project, the team suggested that special attention be Here are some specific conclusions the team given to means of maintaining and improving soil rea.ched about research on each crop. After touring fertility, especially in savanna areas. The evaluators maIze projects at several sites in northern Nigeria, also stressed the need to conduct more socioeconomic the evaluators remarked upon the appropriateness of studies on which to base introduction of new techno­ ?oncentrating on this region, in view of the growing logies and urged PRONAM to develop strategies for Importance of maize in the savanna. They found the extension and farming systems research. trials to be extremely well managed and recom­ mended that the work be further diversified to include additional insect pests and diseases. Their conclusion about rice work at the Institute's NCRE substation at Onne, Nigeria, was that "a lot of ground IITA's role in the NCRE project, which is an integral had been covered in a short time" in the search for part of Cameroon's Institute for Agronomic Research so~utions t<;, the production problems of the high- ' ramfall regIOn. The team urged that after on-station ~IRA), i~ to improve the national research capability m crop Improvement and to accelerate staff develop­ evaluation of rice cultivars testing should be carried out at other locations within and outside Nigeria in ~ent m :esearch and technology transfer. The pro­ Ject conSIsts offour units: (1) maize improvement and cooperation with national.programs. agronomy, (2) rice improvement and agronomy, (3) . The evaluators observed cowpea and soybean trials sorghum and millet improvement and agronomy, and m the northern savanna region of Nigeria. They (4) the Testing and Liaison Unit (TLU). commez:.ted that the white-seeded 60-day cowpea and The evaluation team found NCRE to be an out­ the vanety TVx 3236 are outstanding in yield and standing program and commented that it had made plant type and could significantly increase pro­ remarkable progress during its two years of existence duction and bring down the cost of cowpeas to in identifying varieties that perform well under the consumers. The team also acknowledged the achieve­ varied agroecological conditions of Cameroon and in ment of t~e ~oyb~an breeding team, which has pro­ developing agronomic practices for mixed and mul­ duced vanetl~s w~th .good stora~ility and the ability tiple c:opping systems. These varieties and practices to nodulate WIth mdIgenous rhIZobia. Some of these are bemg. tested under small-farm conditions by the varieties are being tested in nationally coordinated TLU, WhICh also works closely with Cameroonian variety trials and are likely to be released in Nigeria extension agencies in taking research results to as commercial varieties. This work has attracted the farmers. notic~ of .oil mills in northern Nigeria, which are The evaluators cited six reasons for NCRE's suc­ showmg mterest in purchasing locally produced cess so far: (1) there was a great need for intensified soybeans for processing, and it has also stimulated cereals researc.h in Cameroon; (2) overall, the project soybean research programs in Nigeria and other was well conceIved; (3) the Cameroonian government African countries. has strongly supported the project; (4) USAID has provided considerable funding and leadership; (5) New Proj ects IITA has assembled a highly capable staff to work with Cameroonian scientists; and (6) the country's In 1983 two new projectS got underway in Rwanda, a farme~s and other agriculturists have been very cass~va and sweet potato improvement program and receptlve to research results. a proJ ect for research and training in food crops of the Research Support 203 country's savanna region. Under the former an IITA A bulk seed handling unit was completed in root crops breeder, posted in Rwanda, is' working November of 1983 for drying, threshing, cleaning, closely with scientists in the national research sys­ grading, dressing and packeting cereal and grain tem to develop high-yielding varieties and improved legume seed. This unit, which includes an air­ cultural practices. He will also assist in the develop­ conditioned seed store for medium-term storage, will ment of a training program for Rwandaise scientists be instrumental in improving th e quality of seed and later will help coordinate efforts to establish a distributed by IIT A. network of researchers working on cassa va and sweet Installation of three new di esel-driven water potatoes in East Africa. pumps in a new building was completed this year. The aims and activities of the second project are to These pumps provide reliable irrigation on 40 ha of evaluate local varieties of cassava, sweet potatoes, dry season research trials and f) ha of rice paddies. cowpeas, soybeans, maize and sorghun'l, conduct The standard overhead sprinkler irrigation system agronomic trials with these crops, evaluate soils, used at IIT A has been supplemented by irrigation carry out on-farm testing of new technologies, and travellers mainly on maize hybrid seed multiplication develop packages of recommendations for the exten­ fields . sion service. The project provides IITA ' with an The University ofIfe this year agreed to provide an excellent opportunity to verify technologies de­ additional 8 ha of land for tht , Institute's Ikenne veloped under another cooperative venture, the substation and granted right of occupancy for 10 Semi-Arid Food Grains Research and Development years. Development of this static.n continued in 1983 (SAFGRAD) Project in Upper Volta, and to expand with road construction, land grading and drainage research in the semiarid environment to include installation. Two deep wells were drilled, one by UTA mandate crops not dealt with by SAFGRAD. and the other by the Nigerian government to provide water for irrigation , which will he installed in 1984. Since the irrigation will require more work to be done at this site, a living unit consisting of five Porto­ Research Support Units cabins has been purchased. Thi:, unit will provide Farm Management living accommodations for a farm supervisor and two bedrooms for visiting scientists. The Farm Management staff manages IITA's 1,000-ha The Farm Management staff wpported research research facility at Ibadan, its 80-ha high-rainfall work in the savanna zone of Niger ia a t Mokwa, I10rin substation at Onne and 32-ha midrainfall station at and Zaria, using a mobile mechanization unit, which Ikenne. Cooperating with national research stations, does land preparation, planting, spraying, harvest­ the staff also provides support at locations in north­ ing, etc. ern Nigeria to enable IITA scientists to grow trials Staff members also contributed to a ll major train­ under various climatic conditions and soil types. An ing courses and trained students in farm management additional task carried out by Farm Management in and mechanization. The staff also conducted many 1983 was to assist IITA cooperative projects in Upper field tours and received numerous visi tors. Volta, Zaire and Cameroon in developing and improv­ ing their research facilities. Genetic Resources Unit Mechanization of field operations has been em­ phasized over the years because of the increased Plant Exploration and Collection accuracy obtained and the extremely high cost of Plant exploration, suspended sinc ( ~ 1981, was re­ labor in Nigeria. The most important advances made sumed in 1983. In an exploration trip to southeastern in 1983 were mechanization of cowpea harvesttng and Nigeria, a total of 48 germplasm samples were gath­ upland rice planting. Cowpeas were harvested on a ered: 8 of cowpeas, 4 of wild Vigna, 1 of wild commercial scale by cutting and windrowing and legumes, 33 of Asian rice and 4 01' wild Oryza. The then threshing with a Brazilian-manufacturE;!q pick­ Genetic Resources Unit also received donations of66 up combine specially designed for cowpea harvest­ samples of cowpeas, 124 of rice, ~J:3 of Bambarra ing. Seed loss and splitting were minimal with this groundnuts and 254 accessions of other crop species method, which shows promise for commercial farm­ from its cooperators. Twenty-foul' of the 66 cowpea ers in Africa. No-till cone seeding of upland rice trials samples were received from the International Board was begun in 1983 and showed considerable promise of Plant Genetic Resources (IBPGR), 14 from India for saving funds. and 24 from the United States. Thi]'ty-one of the Research staff have been encouraged to use zero rice germplasm samples were provided by the tillage in planting trials, and this system is now used International Rice Research ' Institute (IRRI) , almost exclusively in planting cereals (except swamp Philippines, and 93 by IBPGR. All other crop samples, rice), grain legumes and cassava. totalling 254, were provided by IBPG R. Approximately one third of all research land was At the end of 1983, the unit held a s tock of 11,509 fallowed during the year with a cover crop of Mucuna accessions of cowpeas, 7,585 of rice (0. sativa and O. utilis, which protects the soil, controls weeds and glaberrima), 1,350 of soybeans and 1,2fo() of Bam barra promotes builduP' of organic matter. groundnuts (Tables 2 and 3). 204 Research Support Germplasm Distribution totalling 8,665 germplasm accessions or 88% of the overall distribution by the Genetic Resources Unit. The unit responded to a total of 180 requests this year The unit also provided rice germplasm materials to from 25 countries for a total of 9,846 samples of two CGIAR Institutes, 319 accessions of African rice germplasm; 94 requests were for cowpeas, 20 for rice, to IRRI and 250 African traditional and improved 11 for soybeans and 55 for other legumes. From IITA cultivars of O. sativa to the International Center of scientists there. were 43 requests for cowpeas, 9 for TropicalAgriculture in Colombia. rice , 8 for soybeans and 12. for miscellaneous crops, GermplasmE valuation Table 2. Cowpea germplasm currently available at A total of 7,400 cowpea germplasm accessions were IITA evaluated for resistance to Maruca testulalis and pod Country Number of Country Number of bugs at Mokwa, Nigeria, and sources of moderate of origin Accessions of origin Accessions resistance were identified. The results of this work Benin .......... .. . 277 Tanzania. . . . . . . . . . 370 are reported in the section on grain legume improve­ Botswana . ... . . .. . 14 Togo..... . ... . .. . . 75 ment. The great majority of the germplasm ac­ Cameroon . .. . .. .. . 469 Uganda.... . . . . .. . 70 cessions, most of which are traditional cultivars, Egypt .... . ... . . .. . 345 Upper Volta . . . . . . . 197 were seriously damaged by various insect pests at Ethiopia .. ....... . 6 Zaire . . . .. .. . . . . . . 15 Mokwa. When grown as a sole crop, these cultivars Ghana .. ... ... . . . . 278 Zambia ..... . .. . .. 250 cannot produce pods without insecticide spraying in Ivory Coast . ... . .. . 129 Zimbabwe ......... 7 areas where insect pest pressure is high. Develop­ Kenya ... . ....... . 52 yemen .. ... .. .... . 20 ment of resistant varieties should greatly increase Liberia . ......... . 9 India . . . . . . . . . . . . . 1,935 the yields and reduce the costs of cowpea production Malawi .. .... . .. . . 322 Brazil. . . . . .... .. . . 32 Mali . . ......... . . . 177 United States. . . . . . 799 in Africa. Niger . . .. . ...... . . 700 Selection from Five hundred accessions of rice germplasm col­ Nigeria . ...... .. . . 2,492 mixture. . . . . . . . . 719 lected in the high rainfall region of Central and West Senegal ....... .. . . 17 Other countries . . . . 331 Africa were selected by the unit from its gene bank Somalia .. .. .. . .. . . 3 Unknown . . . . . . . .. 1,245 and given to rice scientists to be screened for re­ Sudan .. ... .. . ... . 46 sistance to diseases prevailing at IIT A' s high rainfall South Africa . . . . .. . 108 Total . . . . . . . . . . . .. 11,509 substation at Onne and for thick root characteristics. These materials were previously screened by the unit, and most were found resistant to leaf blast and some Table 3. Rice germplasm currently available at IITA to rice yellow mottle virus. Country of origin Oryza glaberrima Oryza sativa During 1982 a rice entomologist identified 32 ac­ African countries cessions of rice germplasm that are resistant to stem Benin .. ... . .. .... . .. . . .. .. . o 28 borer from over 750 accessions provided by the unit. Cameroon .. . . . . . . . ... .... . . 65 79 Fifteen of these accessions were confirmed as being Chad . .. . . . .. .. . .. ... .. . . . . . 15 21 resistant to this pest, most of these being O. glaber­ Egypt . . ... ...... . . . .. . . .. . . 2 128 rima, the species that originated in West Africa. Ghana. .. . .... . ............ . 27 82 Gambia .... . ... . . . .. .. .. ... . 39 295 Germplasm Characterization Guinea Bissau .. . . ... . . . . . .. . 22 61 Guinea . . ... ...... . .. ... .. . . 64 214 A total of 1, 290 accessions of cowpeas were character­ Ivory Coast ... ...... . .. .. .. . 83 598 ized for up to 29 characters and over 900 accessions of Liberia .... . ..... . . . . . . . .. . . 644 802 rice for up to 41 characters. The seed coat color Madagascar. ........ . ...... . o 414 of over 6,000 accessions of cowpeas was also Malawi ....... . .. . ........ . . 1 279 characterized. Mali . .. .. . . . . . .. . .. .. . . ... . 73 6 Nigeria .. . ......... . .. .. . .. . 771 775 Sierra Leone . . .. . . .. ... . .. . . 27 311 Multiplication and Rejuvenation Senegal .. .. ... . .. : ~ .... . .. . 73 530 During the year about 3,500 accessions of cowpeas, Tanzania .... . ... ... .. ... .. . 3 267 1,000 of rice and 350 of soybeans were multiplied Upper Volta. . . . . ...... .. ... . 36 47 or rejuvenated because the stock was depleted or Zambia .... . . ... . . . . . . ..... . o 280 the seed viability was low. Over 500 new cowpea Zaire .......... .. ..... . ... . . 1 49 germplasm samples and 1,138 new rice germplasm Non-African countries samples were multiplied and given IITA accession Brazil . . .... . .... . . . .. . . . . . . o 84 numbers. By the end of 1983, the number of cowpea Bangladesh .. .. . .. .... ..... . o 30 germplasm accessions had reached TVu 13,000 and of Colombia . . . . .. . .. . . ..... .. . o 5 rice accessions TOs 12,200. India ... . ........ . ...... . .. . o 16 Philippines . . ........ ... ... . o 27 Others .. ...... ... ...... ... . o 211 Long-Term Seed Conservation To date over 2,000 accessions of cowpeas and 1,000 of Total 1,946 5,639 rice have been tested for seed germination for long- Research Support 205 Table 4. Viability o~ soybean seed after storag~; lIT A, 1983 -------------In-i-ti-a-l -----------~--------------------------- Moisture germination Germinationpercentage after storage a Storage temperature, °C content percentage 4 months 8 months 12 months 17 months TGm479 32.. . .. . ... . ....... .... . . . . ... . . . . . . . 6.0 90 77 56 43 47 32 .' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.0 90 7 33 30 29 32.. .. .. .. . . . . .. .. . . . . . . . ... .. . . . .. .. 14.8 90 0 0 0 0 5, ....................... . .. ... . .. ... . 6.0 90 88 78 69 71 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.0 90 80 67 44 47 5 .................. ...... .. . .... ..... 14.8 90 69 49 26 30 -20. .. ... . ............... ... . ....... 6.0 90 91 83 81 83 -20 .. . . . . . . . . . . . . . .. . . ... . . . .. . . .. .. 11.0 90 91 71 72 71 -20 . . . . . . . . . .. .. .. ... . . .. . . . . . . . .... 14.8 90 89 62 53 52 TGm579 32.... .. ... ..... ......... .... . .. .... . 7.0 97 93 90 71 62 32 . . .. . . . . . .. . . . . . . . . . .. .. . . . .. . . ... . 14.0 97 58 0 0 0 32 .. .. .... . . . . . . . . .. .. ... . . . . ... . .. .. 16.0 97 4 0 0 0 5 . ....... .. . . ... .. .... . . ....... .. .... 7.0 97 91 93 80 82 5 . .... ....... .. ... . ... . ...... .. ... . .. 14.0 97 91 54 40 41 5.. . ....... . ... ....... . .............. 16.0 97 64 39 49 43 -20 ................................. 7.0 97 100 97 93 95 -20. ... ... . ... ..... . ... . . . . .. ....... 14.0 97 103 56 62 59 -20 ...... ... . . . . ....... . . .. ........ . 16.0 97 102 43 58 57 ·Computed as a percentage of initial germination. term conservation. Only those with a germination Seeds were conditioned to moisture contents of6 to percentage above 87 were dried to less than 7% 16% for soybeans and 7.26 to 15.71% for cowpeas moisture content before being sealed in aluminum either in a room dehumidified by silica gel or in a cans for long-term storage at -20°C. By the end of moist atmosphere of almost 100% relative humidity. 1983, a total of 1,285 accessions of cowpea seeds and The moisture content of the seed was maintained by 865 of rice had been stored in 3,840 and 1,066 cans, hermetically storing it in sealed aluminum en velopes respectively. In addition, about 1,350 accessions of containing 100 seeds. Between 6 and 15 packets of soybeans and 500 of West African rice were stored in seed with a constant moisture content were stored at deep freezers in aluminum foil packets.-N.Q. Ng each of three constant temperatures: -20°C (deep freezer), 5°C (refrigerator) and 32°C (drying room). Seed Longevity Studies The packets of seeds were withdrawn from storage at regular intervals and all seeds were tested for ger­ The main concern of germplasm conservation is to mination (one packet per test divided into two prevent loss of seed viability by identifying storage replicates) between moist rolled paper towels at a conditions under which seed longevity is prolonged temperature of 29°C ± 2°C in a seed germinator. as much as possible. The longer the seeds can be kept The seed longevity of all cowpea and soybean viable, the less frequently will they require reju­ cultivars deteriorated faster at the higher moisture venation and the more effectively will the genetic content and at higher storage temperatures (Tables 4 integrity of the germplasm be maintained. and 5). The storage temperature and moisture con­ To gain a better understanding of the influence of tent combined had an even more pronounced effect on genotype, temperature and moisture content on seed seed longevity. For instance, TGm 479 dropped from longevity, experiments were begun in 1982 with seeds an initial seed germination of90% to 0% in only four of two soybean (TGm 479 and 579) and three cowpea months of storage at 32°C and 14.8% moisture con­ cultivars (VITA-I, VITA-4 and VITA-5) stored under tent, whereas the same seed lot retained around 83% various combinations of temperature and moisture of its initial seed viability during 17 months of storage content. Soybean cultivar TGm 479 is reported to at -20°C and 6% moisture content. But when the have poor seed storability. seed was stored for 17 months at -20°C and 14.8% All the soybean seeds were provided by the soybean moisture content or at 32°C and 6% moisture content, breeding program from harvests in October and only about 50% of the initial seed viability was November 1981; the three cowpea cultivars were maintained. produced by the Genetic Resources Unit during the The study also revealed that seeds of different same season. All seeds were kept under ambient genotypes differ in longevity when stored in similar conditions for three to four months after harvesting environments. TGm 479 deteriorated faster than TGm and drying. The germination of all five cultivars was 579, and their differences in percent seed germination above 90% when the investigation began. were significant after 12 months of storage. 206 Research Support Another finding of the experiments was that both the rate of seed deterioration under storage. It was the storage temperature and moisture content have noted, however, that soybean seed loses its viability about the s'ame effect on cowpea as on soybean seed at an alarmingly rapid rate. The seed germination of longevity, although it appeared that cowpeas had TGm 479 dropped by more than 5% from an initial greater seed longevity than soybeans. For instance, seed viability of 90% in less than 4 months of storage VITA-1 and VITA-5 had a seed moisture content of at -20°C and 6% moisture content. The germination 14.22% and 14.32%, respectively, or about the same as of TGm 579 dropped by 5% after 12 months of storage the soybean variety TGm 579 (14 %), but they could be at -20°C and 7% moisture content. stored at 32°C for more than 10 months, compared to 4 The IBPGR's panel of experts have recommended months for TGm 579, before their seed viability that when a seed lot drops 5 to 10% in germination dropped toO%. Their storage life in this environment from its initial seed viability, then it should be was at least twice that ofTGm 579. regenerated as soon as possible. Our practice is to In these studies deterioration of both soybean and regenerate an accession when the germination per­ cowpea seeds was greatly reduced when they were centage of the seed lot becomes less than 85. Thus, we stored at low temperature (-20°C) and low seed may have to regenerate .TGm 479 or other soybean moisture content. Within the range of seed moisture cultivars with similar seed longevity once every year contents and storage temperatures investigated in if we cannot maintain higher initial seed viability these studies, it appeared that the lower the seed (above 90%) before storage. Further investigation moisture content and storage temperature, the lower into the storability of this genotype at a lower Table 5. Viability of cowpea seed after storage, lITA , 1983 Moisture . Initial Germination percentage after storage a content, percent germination 8 10 12 16 19 23 Storage temperature, °C wet basis percentage months months months months months months VITA-1 32 .. .... .... .. . ... . . . ...... ... 7.51 93 89 75 73 75 73 82 32 ......... .. ....... . .... . ... . . 8.51 94 85 79 66 76 77 32 .......... . ... . .. . .......... 14.22 99 42 35 0 1 0 5 .... .. .............. ........ 7.51 93 90 93 94 95 84 5 . ... ... ..... . . ......... .... . 8.51 94 83 77 92 94 77 5 ... . . . .... ... . . . .. . .. .. ... .. 14.22 99 81 63 53 61 63 -20 .. .... ... . .. . . ... ... .. .... 7.51 93 99 99 99 97 97 -20 .. . ..... . . . ............... 8.51 94 97 96 98 96 96 -20 ... .. . . . .. .. .............. 14.22 99 91 85 81 83 81 VITA-4 32 ............................ 7.38 98 88 77 85 88 86 71 32 ........ ... . . ..... ... ....... 8.54 92 89 89 76 87 85 88 32 ............................ 12.46 96 75 63 68 54 49 60 32 ............................ 15.45 98 84 63 60 16 14 o 5 . . .. ... . ........ . ........... 7.38 98 83 86 94 92 94 80 5 ............................ 8.54 92 96 87 94 93 94 59 5 .. .... .. .. ............ . . .... 12.46 96 90 73 71 75 73 71 5 . . .. . . .. ...... ... .. . . . . ..... 15.45 98 97 88 82 76 76 80 -20 ... .. . . .. . .. ..... . ...... . . 7.38 98 95 94 96 96 96 89 -20 ... . .... ............. . .... 8.54 92 97 97 98 99 98 87 -20 .......................... 12.46 96 94 78 83 83 83 60 -20 . .. .. . ...... . ........ ... .. 15.45 98 92 87 87 88 90 83 VITA-5 32 ............................ 7.26 97 96 91 89 87 81 93 32 .... . .. .... ... . ....... .. .... 8.46 99 95 91 85 91 92 92 32 ........... ". ................ 14.32 98 94 74 69 12 25 o 32 ............................ 15.71 98 37 31 0 0 0 o 5 ............................ 7.26 97 98 93 96 93 92 96 5 . . .... . ...... ... .... ........ 8.46 99 98 97 94 95 94 97 5 ..... . . . ... ...... .. ... . .... . 14.32 98 92 77 82 84 76 80 5 ................. . . ... . .. .. . 15.71 98' 85 46 62 80 71 87 -20 .. .... . ......... ... ....... 7.26 97 96 99 99 99 98 95 -20 ... . ...... . ... ... . ........ 8.46 99 99 99 95 97 95 81 -20 ..... ........ . . ........ . .. 14.32 98 94 90 80 80 82 86 -20 ... ...... .... .. ........... 15.71 98 92 61 53 71 76 84 aComputed as a percentage of initial germination. Research Support 207 moisture content may be ~seful. The influence of Number of external users per year prestorage conditions and field weathering on seed 3,000 r-----...,......---------------, longevity should also be investigated.-N.Q. Ng and A :A. Osunmakinwa Biometrics Unit A new biometrician Joined the staff at IITA in November 1983. His main duties are to consult with 2,000 scientists and research scholars on designs of agricul­ tural field experiments and to review proposed de­ signs before the experiments are carried out. To centralize experimental data, a data analysis service and an intercropping data bank are planned for 1984. Research on the statistics of intercropping is in 1,000 progress in cooperation with the Department of Applied Statistics, Reading University, United Kingdom. GENSTAT (release 4.04A), a statistical package developed by the Department of Statistics, Rotham­ sted Experiment Station, United Kingdom, was in­ stalled recently on IITA's Vax 11/750 computer o system. GENSTAT is a very comprehensive data 1977 78 79 80 81 82 83 management and statistical analysis system. It is Figure 1. Use of the IITA Library and Documentation well suited to IITA because the Institute's field ex­ Center by non-IITA staff. . periments require relatively complex designs owing to the great heterogeneity of African soils. The biometrician plans to give seminars on the use of GENSTAT for scientists and research scholars at regular intervals in 1984. reprints on specialized subjects such as yams, plan­ tains and cowpeas. Current acquisitions were an­ Analytical Services Laboratory nounced every month through two media: Selected List of Publications Received in the Library and Grain The laboratory continued to perform routine chemi­ Legume Current Titles. cal analysis of soil, plant and water samples, handling Use of the library by IITA staff and trainees­ a total of391 requests during the year. The majority of continues to increase. The library has maintained its these came from lITA research programs, but 44 came status as the major information resource for the from other organizations. The laboratory analyzed agricultural and biological research and training 10,268 water samples for various elements and a total community of Ibadan. External users of the library of 4,812 soil samples. Routine chemical and physical include university staff, postgraduate students, re­ assays were performed for pH, N, P, K, exchangeable search staff of various agricultural research in­ cations, acidity, organic carbon, clay, silt and sand stitutes as well as consultants. The number of users content. The laboratory analyzed 4,596 plant samples not associated with IIT A increased from 380 in 1977 for macro- and micronutrient elements and root and to 2,900 in 1983, more than a seventyfold increase tuber extracts for cyanide. A total of 83,249 assays (Fig. 1). were performed during 1983. Sponsorship of the International Grain Legume Some research on the methodology of soil analysis Information Centre by the International De­ was carried out; a new method for measuring cation velopmentResearch Centre, Canada, was extended to exchange capacity was tested on a number of soils December 1983. During the year we developed phase representative of those in the humid and sub humid III of the Grain Legume Information Project. This tropics. The method was modified to make it suitable phase, which will run for three years, features micro­ for use in small laboratories with limited facilities. fiche production and distribution, development of a computerized data base on grain legume information Library and Documentation Center and documentation of Brazilian cowpea research. Three issues of the Tropical Grain Legume Bulletin The library added 1,400 books and 1,850 volumes of (Numbers 26, 27 and 28) were published in 1983. The periodicals to its collection during 1983. In December camera-ready copy of the fourth volume of the world 1983 the library's holdings consisted of 26,850 vol­ literature on cowpeas was produced. The volume, umes of periodicals, 24,400 books, 4,300 pamphlets, which includes 497 abstracts representing the litera­ 3,550 microform items, 1,860 slides and 83 audio­ ture published during 1981 and 1982, is in press and cassettes. In addition, the library has over 6,500 will be distributed during 1984. 208 Research Support Public Affairs and Development • Workshop on Integrated Pest Control for Grain Legumes, Goiana, Brazil, 5-9 April. Communications and Information • International Federation of Agricultural Research The office distributed about 28,000 copies of lIT A Systems for Development (IFARD) Congress, 6- 10 publications to 4,800 requestors in 131 countries June. during the year. • Second Triennial Symposium of the International Three publications were reprinted: Society for Tropical Root Crops-Africa Branch, • Tasks for the Eighties : A Long-Range Plan Douala, Cameroon, 14-19 August. • Role of Mulching Techniques in Tropical Soil and • International Fertilizer Development Center Water Management Research Planning Meeting on Sources and • Proceedings of the International Workshop on Management of Phosphorus and Nitrogen in Sub­ Cassava Saharan Africa, 16-18 November. The following lIT A publications were produced at • Soybean Utilization Workshop, 5-9 December. the Institute and printed at the headquarters' print­ Twenty-seven research seminars were presented, ing plant or abroad: including four special seminars on instrumentation. • IITA Research Briefs, Vol. 4, Nos. 1,2 and 3 More than a hundred student groups visited lITA to • The Food Crisis in Tropical Africa: The Challenge increase their knowledge of agriculture and learn ofIITA about technologies being developed at the Institute. • La Crise Alimentaire en Afrique Tropicale: Le Defi de l'IITA • IITA Record of Publications, Vol. 2 • Field Guide to Common Weeds of IITA and Their Control • Cowpea Research at IITA • Proceedings of the First Workshop of the All-Nigeria Coordinated Cowpea Research Program • No-Till Farming: Soil and Water Conservation and Management in the Humid and Subhumid Tropics • Visitors' Guide • Le Guide du Visiteur • Training and Post-Graduate Research Oppor- tunities at IITA • Formation et Recherche Post-Universitaire a l'IITA • Tropical Grain Legume Bulletin, No. 27 • IITA Research Highlights, 1982 • IITA Le Point de la Recherche, 1982 • IITA Annual Report, 1982 Two new printing presses and accessories were installed during 1983. Two students from the University'OfIbadan doing their master's degrees in Communication Arts carried . out their research at lITA during the year under supervision of the staff of the Communications and Information Office. Two research training associates (photographers), one from the Federal Agricultural Coordinating Unit, Ibadan, the other from the Faculty of Veterinary Medicine, University of Ibadan, also underwent training at lITA . The office represented the Institute at the Inter­ national Book Fair in Frankfurt, West Germany. Conference and Visitors' Center In 1983 seven workshops and conferences were hosted by lITA in Ibadan or held at other locations by the Institute and cooperating organizations : • Farming Systems Research Methodology Work­ shop, 14-18 March. • Caribbean Regional Root Crops Workshop, Jamaica, West Indies, 5-9 April. Appendix 209 Appendix: IITA Weather Rainfall (mm ) 280r-----------------·------------~ IITA , Ibadan An approximately one-month delay in the start of the Univ. of Ibadan rainy season and very low rainfall in the second half 240 /( 1953-1982) of the year resulted in a poor crop year, as was the case in 1982 (Fig. AI). Total rainfall for 1983 was 28% below normal (1953-1982), making this the fourth 200 driest year in 31 years. Insolation was nearly normal, on the average, but significantly above normal dur­ ing periods of rainfall deficit. Temperatures were 160 mostly above normal and so were relative humidity and pan evaporation (Table AI). I 120 I I Rainfall and Evaporation I The year was marked by extremely dry conditions I 80 I from the outset. There was no rainfall in January, and I evaporative demand was the highest on record for I that period. Februaryand March were essentially the I same. By April the cumulative evaporation had risen 40 I to 667.4 mm, compared to a total rainfall of only 7.1 I mm. ~~ " The rains made a false start in April, but the OL~~~~ __L _l_~_L_L-L~ __~ extreme aridity preceding and following these rains Jon Feb Mar Apr May June'July Aug Sept Oct Nov Dec made them ineffective. Tetal evaporation for the month exceeded rainfall by 20%. The moisture bal­ Figure AI. Mean monthly rainfall, Ibadan. ance in May and June was favorable, however (Fig. A2). Regular rains during that period were conducive to rapid growth of late planted crops. The total demand. Two unusual storms in December accounted amount of rainfall received in May (236.2 mm) was the for much of the 85.9 mm of rainfall received in that highest recorded for the month over the period month; this amount was a record for December. Total 1953- 1982. evaporation for the year was 1,746.1 mm, the highest A wet period in mid-July followed a slackening of yearly total observed. the rains in the last week of June and first week of July (Fig. A2). This rain proved to be crucial for the Sky Conditions and Solar Radiation first season crops since no rain fell for nearly six Insolation was mostly just below normal, although weeks afterwards. August was extremely dry, with large, positive departures from the multiannual only 36.1 mm of rain, 22.1 mm of which fell on 29 means were recorded in July (+9%), September August. (+8%) and October (+ 11 %), all of which had below There was no second cropping season since rainfall average rainfall. August was unusual, having less through November was very much below moisture than average insolation coincident with extremely Table AI. Summary of climatic data, UTA, Ibadan, 1983 Total Total evapor· Solar radia· Mean wind rainfall, ation, hon, g·cal/ Temperature,OC ReI. humidity, % speed, mm mm cm2/day Max. Min. Mean Max. Min. Mean mph January . . . .. .. .. . .. .. . . . 0.0 251.2 385.6 32.5 18.3 25.4 63 27 45 3.7 February . . ..... . ..... . . . 3.9 193.4 422.9 35.6 22.9 29.2 87 29 59 3.0 March ... . ... . . .. .. . . . . . 3.2 222.7 450.3 36.7 23.9 30.3 92 27 60 3.3 April ..... . ... . ... . ... . . 80.8 170.0" 458.6 34.7 23.4 29.0 97 48 73 3.3 May ...... .... ..... .. . .. 236.2 154.8" 437.2 31.6 23.2 27.5 98 61 80 3.0 June . . . .. .. . ...... .. . . .. 160.8 118.8" 381.8 29.2 22.6 25.9 99 67 83 2.6 July . ... . . ....... . . . . . . . 108.4 86.2" 371.6 27.5 21.8 24.7 98 69 84 2.2 August . . . . . ....... . .. . .. 36.1 75.3" 304.9 26.5 21.5 24.0 99 72 86 September .. .. . ... . . . ... . 139.2 93.9" 398.1 28.5 22.3 25.4 99 66 83 2.7 October . . . .... ..... .... . 38.3 129.2 453.6 30.6 23.1 26.9 98 56 77 2.4 November ... . ......... . . 28.6 145.3 426.9 32.3 23.3 27.8 96 46 71 2.7 December .. . . . . ......... 85.9 103.9 380.0 30.7 22.2 26.6 96 52 74 2.1 ·Values adjusted for days for which no data were obtained. 210 Appendix Rainfall and evaporation ( mm / day) value for the period since 1953. Daytime temperatures were slightly cooler than normal in June and July, 12.0 but warmer temperatures prevailed .through the remaining months of the year, except December, Evaporation which had cooler maximum temperatures (the ave­ 10.0 :/ rage difference from the mean was -1.6°C). /Rainfall .II. Wind speeds were by and large near average. The significantly higher values in January reflect the S.O .. : ~ ,. # U I , •• unusually strong harmattan that prevailed (Table • I• u• t ~\ AI). The weaker flow in June and July was evidently 6.0 , the result of the reduced incidence of storms during that period. 4.0 IITA,Onne 2.0 As at Ibadan, the rains started late at the Institute's substation near Onne in southeastern Nigeria. The weather was dry from January through March. April, Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec with 128.6 mm of rainfall, provided the earliest Figure A2. Weekly mean rainfall and evaporation, rITA, opportunity for planting (Table A2). 1983. Excessive rainfall in May and June made up for the cumulative deficit that had occurred up to that time. low rainfall. This was consistent with the parallel Rainfall was again below average from July through observation of actual sunshine hours, which aver­ October. November was also abnormally dry, signal­ ling an early beginning of the dry season. aged 1.7 h/day for the month, compared to the long­ Departures from the long-term averages for mean term mean of 2.6 h. global radiation were generally negative. February Temperature and Relative Humidity and September were exceptions, their respective means being 9 and 12% above normal. Recurrent waves of harmattan in January kept at­ Maximum daytime temperatures were higher than mospheric humidity very low and contributed to normal from January through April but lower during increased radiative cooling at night (Table AI). the rest of the year. As at Ibadan March was the Minimum temperatures fell 1.8°e below normal, and hottest month, the temperature being 2.9°e above the mean relati ve humidity stood at 45%, compared to normal. the multiannual average of61 % for the period. There Minimum temperatures were above average, ex­ was a late resurgence ofthe harmattan in the first half cept in Jan:uary, when the temperature was O.5°e of March, but it had a less drastic effect on atmos­ below normal. Relative humidity was lower than pheric moisture content. average in all months; the difference was most Higher than normal temperatures prevailed from pronounced in January (51 %, compared to a mean of February through June (Table AI). The largest 79%), reflecting the harmattan that prevailed during departure (2.9°e) from the mean maximum tempera­ that period.-T.L. Lawson . ture (36.7°C) occurred in March. This was the highest Table A2. Summary of climatic data, IITA, Onne (Port Harcourt), 1983 Total, Solar radia- rainfall, tion, g-cal/ Temperature, .oC Relative humidity, % mm cm2/day Max. .Min. Mean ' Max. Min. Mean January .... ......... .... 0.0 354.0 32.9 20.3 26.6 82 19 51 February ........ . .... ... 1.3 414.8 35.0 24.1 29.6 97 35 67 March . ................. 42.0 378.4 34.9 25.4 30.2 97 38 68 April. . . .... . .. .. ........ 128.6 352.4 32.2 24.7 28.5 99 56 77 May .................... 314.9 304.0 30.6 24.7 27.7 96 64 81 June ... ..... ........... . 324.8 300.7 28.6 24.0 26.4 96 67 81 July .................... 263.9 269.8 27.3 23.4 25.4 98 73 86 August .................. 242.1 270.7 26.7 23.3 25.0 99 74 87 September . ....... . ... .. . 361.5 364.4 28.0 23.4 25.7 99 70 85 October .......... .... ... 230.8 341.2 28.9 23.0 25.9 99 65 82 November .. ...... . ...... 40.2 324.2 29.8 23.5 26:7 99 63 _ 81 December ...... .... .. . . .. 79.3 3,1 9.3 30.2 22.4 26.3 98 57 .78 Personnel 211 Personnel L.A. Oke, senior research technician O.A. Oladimeji, senior research technician H.N. Pham, Ph.D., CIMMYT maize breeder* Administration . M. Rodriquez, Ph.D., agronomist, SAFGRAD, Upper Volta E.H. Hartmans, Ph.D., director general A.C. Roy, Ph.D., agronomist, NCRE, Cameroon B:N. Okigbo, Ph.D., D.Sc., deputy director general (re­ H. Talleyrand, Ph.D. , agronomist, NCRE, Cameroon turned from sabbatical leave in October) K. Wasano, Ph.D., rice breeder and geneticist, JICA L.H. Shebeski, D.Sc., deputy director general and interim expert, Saga University, Saga, Japan director of research* Kaung Zan, Ph.D., ffiRI liaison scientist M.A. Akintomide, B.S., AICTA, director of admini­ stration J.E.G. Haakansson; M.B.A., director of budget and Grain Legume Improvement Program finance S.R. Singh, Ph.D., director B.A. Adeola, ACIS, accountant R.A. Adeleke, senior research technician K.A. Aderogba, D.P.A .. , FCIS, principal administrative V.D. Aggarwal, Ph.D., plant breeder, Upper Volta officer J.O. Akinwande, senior research technician C.A. Enahoro, administrative assistant to the director S. Asanuma, Ph.D., microbiologist general K. Dashiell, Ph.D., plant breeder E.A. Fox, M.S., manager of information systems* F .A. EI Sayed, .Ph.D., plant breeder L.J. McDonald, B.A., computer manager M. Gowman, visiting scientist, ICI, pest management 0.0. Ogundipe, M.D., medical officer J. Hohenberg, Ph.D., microbiologist M.E. Olusa, assistant to the director for administration L.E.N. Jackai, Ph.D., entomologist E.A. Onifade, security superintendent* E.A. Kueneman, Ph.D., plant breeder D.J. Sewell, dormitory and food service manager N. Muleba, Ph.D., agronomist, SAFGRAD, Upper Volta R.O. Shoyinka, B.S., personnel manager B.R. Ntare, Ph.D., plant breeder S.J. Udoh, AMNIM, chief accountant G.A. Odekunle, senior research technician A. Yusuf, B.S. , controller of stores H. T. Ogundimu, executive secretary J. Okogun, research assistant Cereal Improvement Program R.K. Pandey, Ph.D., agronomist, IITA/ffiRI, Philippines V. Parkinson, Ph.D., pathologist Y. Efron, Ph.D., director Y.S. Rathore, Ph.D., entomologist, SAFGRAD, Upper A.O. Abifarin, Ph.D., IITA liaison scientist, WARDA, Volta Liberia W.R. Root, Ph.D., plant breeder, Zaria, Nigeria M.S. Alam, Ph.D., rice entomologist D.A. Shannon, Ph.D., agronomist D. Akibo-Betts, Ph.D., rice entomologist S.A. Shoyinka, Ph.D. , plant breeder, Zaria, Nigeria K. Alluri, Ph.D., rice agronomist/breeder B.B. Singh, Ph.D., plant breeder V.L. Asnani, Ph.D., SAFGRAD, project leader, Upper E.E. Watt, Ph.D., plant breeder, Brazil Volta F. Wiedijk, Ph.D., entomologist E.A. Atayi, Ph.D., chief of party and agricultural econ- omist, NCRE, Cameroon Root and Tuber Improvement Program M. Bjarnason, Ph.D., CIMMYT maize breeder J. Braide, Ph.D., maize agronomist S.K. Hahn, Ph.D., director J. Chung, Ph.D., maize breeder, NCRE, Cameroon A.M. Almazan, Ph.D., biochemist/food technologist Z.T. Dabrowski, Ph.D., maize entomologist M.N. Alvarez, Ph.D., plant breeder O.P. Dangi, Ph.D. , sorghum and millet breeder, NCRE, K.V. Bai, Ph.D., cytogeneticist* Cameroon F.E. Brockman, Ph.D. , agronomist and project leader, R. Dobson, Ph.D., rice pathologist PRONAM, Zaire H. Ebadan, senior research technician F .E. Caveness, Ph.D., nematologist L. Everett, Ph.D., maize breeder E.M. Chukwuma, research associate J.M. Fajemisin, Ph.D., maize pathologist/breeder W.W. Fiebig, M.s., extension agronomist, PRONAM, B.A. Gbadamosi, senior research technician Zaire* J. Gibbons, Ph.D., rice breeder T. Haug, Ing., entomologist, FAO associate expert T.G. Hart, Ph.D., chief of party, NCRE, Cameroon* R.D. Hennessey, Ph.D., entomologist, PRONAM, Zaire D. Janakiram, Ph.D., rice breeder, NCRE, Cameroon H.R. Herren, Ph.D., entomologist V.T. John, Ph.D., rice pathologist K.T. Lawai, administrative assistant F.H. Khadr, Ph.D., maize breeder, Zaria, Nigeria K.M. Lema, Ph.D., entomologist J. Kikafunda-Twine, agronomist, NCRE, Cameroon B. Loehr, Ph.D., entomologist, Brazil S.K. Kim, Ph.D., maize breeder E. Madojemu, B.Sc., research assistant D. Makonen, Ph.D., maize breeder (visiting scientist), P. Neuenschwander, Ph.D., entomologist Addis Ababa University, ~thiopia S.Y.C. Ng, M.S., tissue culturist T.M. Masajo, Ph.D., rice breeder J.A. Otoo, Ph.D., agronomist/breeder J. Mareck, Ph.D., maize breeder S.Y. Pandey, Ph.D., extension agronomist, PRONAM, D. McHugh, extension agronomist, NCRE, Cameroon Zaire E. Navasero, M.S., rice quality specialist D. Perreaux, Ph.D., plant pathologist* N.V. Nguu, Ph.D., rice agronomist H.J. Pfeiffer, Ir., agronomist and project leader, CNRCIP, D.A. Ogundare, executive secretary Cameroon 212 Personnel G.1. Servant, M.B.A. , administrator, PRONAM, Zaire D.W. Sirinayake, training officer F. Schulthess, Ing., entomologist, FAO associate expert A.P.Uriyo, Ph.D., training officer/agronomist R.L. Theberge, Ph.D., plant pathologist A.M. Varela, B.Sc., entomologist, Brazil M. International Programs Veloso, physical plant services officer, PRONAM, Zaire J.A. Whyte, Ph.D., plant breeder, CNRCIP, Cameroon E.R. Terry, Ph.D., director J.S. Yaninek, M.s., entomologist M. Anyide-Ocloo, bilingual secretary E.F. Deganus, B.S., CAR, administrator Farming Systems Program F.O. Ogunyemi, FCCA, accountant A.K. Owusu-Sarpong, bilingual secretary C.H.H. ter Kuile, Ph.D., director A.S.R. Juo, Ph.D., deputy program director and soil Farm Management scientist C. W. Agyakwa, B.Sc, senior research technician D.C. Couper, M.S., farm manager S.A. Ajirenike, B.Sc., research assistant E.A. Bamidele, farm superintendent 1.0. Akobundu, Ph.D., weed scientist S.L. Claassen, M.S., assistant farm manager M. Ashraf, Ph.D., agricultural economist P.V. Hartley, B.S., farm engineer P. Ay, Ph.D., socioeconomist P.D. Austin, B.S., officer in charge, Onne, Nigeria R. Balasubramanian, Ph.D., soil fertility specialist, BMG II project, Rwanda Genetic Resources Unit P.K. Balogun, B.Sc., research assistant E.A. Baryeh, Ph.D., agricultural engineer N .Q. Ng, Ph.D., head and plant geneticist A.O. Dabiri, B.Sc., research associate M. Davids, Ir., plant scientist, FAO associate expert A. Evers, Ir., associate water management engineer A.A. Osunmakinwa, M.S., research associate H.C: Ezumah, Ph.D.,agroI).omist M.O. Ajala, M.S., research associate C. Garman, M.S., agricultural engineer T. Gebremeskel, Ph.D., agricultural economist Virology Unit H. Grimme, Ph.D., visiting soil scientist, Bimtekof/GTZ N. Hulugalle, Ph.D., soil scientist H.W. Rossel, Ir., virologist B.T. Kang, Ph.D., soil scientist G. Thottappilly, Ph.D., virologist C.C. Kiwamu, B.Sc., research assistant J.W.M. van Lent, Ir., virologist* T. Kosaki, Ph.D., soil scientist M. T. Laditi, executi ve secretary Analytical Services Laboratory R. Lal, Ph.D., soil scientist T.L. Lawson, Ph.D., agroclimatologist J.L. Pleysier, Ph.D., head C.A. Moradesa, senior research technician S.K. Mughogho, Ph.D., soil scientist Biometrics K. Mulongoy, Ph.D., microbiologist H.J.W. Mutsaers, Ph.D., agronomist J. McGuire, Ph.D., biometrician* N.C. Navasero, B.S., associate agricultural engineer K.N. Nguyen, Ph.D., biometrician D.S. Ngambeki, Ph.D., agricultural economist M.A.O. Nwaogwugwu, research associate Library and Documentation Center F. Nweke, Ph.D., associate economist F.O. Ochiobi, executive secretary S.M. Lawani, Ph.D., head P.S.O. Okoli, Ph.D., agronomist* M.A. Aluko, senior bindery superintendent . S.O. Olubode, research associate S.B. Akande, M.L.S., assistant cataloger O.A. Opara-Nadi, Ph.D., soil scientist* G.O. Ibekwe, B.A., principal librarian O. A. Osinubi, M.Sc., research associate E.F. Nwajei, B.A., acquisitions librarian J.A. Poku, Ph.D., weed scientist M.O. Odubanjo, B.S., cataloger M. Price, Ph.D., agronomist and team leader, BG II project, Rwanda Public Affairs and Development R.A. Raji, research associate R. Swennen, !r., plantain agronomist J.E. Keyser, B.S. , assistant director A.B.M. van der Kruijs, Ir., soil scientist, Onne, Nigeria J. O. Oyekan, B.S., head, communications and information A.H.S. Vanelslande, !r., FAO associate expert, soil B. Bakare, conference officer physics S. Berberich, B.S., writer* D. Vuylsteke, Ir., plant physiologist B. Fadare, senior photographer G.F. Wilson, Ph.D., agronomist F .M. Gatmaitan, B.S., senior graphic designer J.C.G. Isoba, M.S., communications officer, publications Training Program N.C. Russell, M.A., editor A.K. Shiwoku, senior executive secretary W.H. Reeves, Ph.D., assistant director and head L.A. Amavi, executive bilingual secretary Physical Plant Services G.A. Cambier, Lie., translator/interpreter C. Duval, Lie., translator/interpreter J . G. H. Craig, assistant director for physical plant services E. Molinero, Lie., translator/interpreter E.O.A. Akintokun, research vehicles service officer C. Puttevils, Lie., translator/interpreter A. Amrani, heavy equipment service officer Collaborators and Trainees 213 A.C. Butler, buildings and site service officer O.B. Arene, program leader for cassava and pathologist, O.O.A. Fawole, automotive service officer NRCRI, Umudike, Nigeria J.M. Ferguson, fabrication/water utility service officer T. Badra, nematologist and leader, F AO/NIHORT, Ibadan, N. Georgallis, scientific/electronics service officer Nigeria J. Lukowski, electrical service officer J. Baumgaertner, entomologist, Federal Institute of M.O. Yusuf, construction site engineering service officer Technology, Zurich, Switzerland A.C. Bellotti, entomologist, CIAT, Cali, Colombia F.E. Bennett, director, CIBC, Curepe, Trinidad *Left during the year. A.1. Carpenter, UNDP/FAO, Ministry of Agriculture, Zanzibar, Tanzania H.R. Chheda, Department of Agronomy, University of Collaborators and Ibadan, Nigeria M.T. Dahniya, project leader of root and tuber improve­ Trainees ment, Njala University College, Njala, Sierra Leone V. Delucchi, director, Phytomedicine Institute, Zurich, Cereal Improvement Program Switzerland O.A. Egunjobi, Department of Agricultural Biology, Research Scholars: University ofIbadan, Nigeria A. Grela (Belgium), University of Gembloux, Belgium L.S.O. Ene, director and breeder, NRCRI, Umudike , J.K. Lekunze(Cameroon), University oflbadan, Nigeria Nigeria G.N. Ngala (Cameroon), University oflbadan, Nigeria A. Fritschi, entomologist, Federal Institute of V.A.O. Okoth (Uganda), Reading University, England Technology, Zurich, Switzerland J. Omoregbee (Nigeria), University oflbadan, Nigeria D.J. Greathead, CIBC, London, England A.P. Gutierrez, entomologist, Division of Biological Grain Legume Program Control, University of California, Berkeley, California Collaborators: M. Janssens, plant breeder, Institute of Agricultural M. Alexander, Cornell University, Ithaca, New York, Sciences of Burundi, Bujumbura, Burundi N.B. Lutaladio, co-director, PRONAM, M'Vuazi, Zaire USA S. Lyonga, coordinator, CNRCIP, Ekona, Cameroon C.A. Atkins, University of Western Australia H. Maraite, head, Phytopathology Laboratory, Catholic C.J. DeMooy, leader, Colorado State University/ Botswana Cowpea Collaborative Research Program, University of Louvain, Louvain-Ia-Neuve J. Meyer, professor, Phytopathology Laboratory, Catholic Gaborone, Botswana University of Louvain, Louvain-Ia-Neuve, Belgium A.R.J. Eaglesham, Boyce Thompson Institute, Ithaca, D. O'Donnell, entomologist, CIBC, Silwood Park, Ascot, New York, USA England M.I. Ezueh, coordinator (cowpeas), NCRI, Ibadan, Nigeria 0.0. OkoIi, assistant director and leader of breeding, I. Fawole, cowpea breeder, University oflbadan, Nigeria NRCRI, Umudike, Nigeria T.A.O. Ladeinde, University ofIbadan, Nigeria F. Quak, head, Virology Unit, IPO Wageningen, T.A. La Rue, Boyce Thompson Institute, Ithaca, New N ether lands York, USA J.N. Sasser, principal investigator, International O. Leleji, IAR, ABU, Samaru, Nigeria Meloidogyne Project, Department of Plant Pathology, J.A. Odebiyi, University oflbadan, Nigeria North Carolina State University, Raleigh, North B.A. Okusanya, NCRI, Ibadan, Nigeria Carolina O. Omueti, IAR&T, Ibadan, Nigeria L.A. Wilson, dean, Faculty of Agriculture, University of A.K. Raheja, IAR, Ahmadu Bello University, Samaru, the West Indies, Trinidad Nigeria M. Yaseen, entomologist, CIBC, Curepe, Trinidad Research Fellows: M. Owusu-Akyaw (Ghana), University of Science and Research Fellows: Technology, Ghana S.K. Asiedu (Ghana), McGill University, Canada Mbe-Mpie Mafuka (Zaire), Catholic University of N.B. Lutaladio (Zaire), University ofIbadan, Nigeria Louvain, Belgium M.N. Mahungu (Zaire), University oflbadan, Nigeria A.B. Salifu (Ghana), University of London , England J .A. Otoo (Ghana), University of Ghana M. Ta' Ama (Togo), University ofIbadan, Nigeria Research Scholars: Research Scholars: J. Abadassi (Benin), National University of Benin K.N. Ahousandjinou (Benin), National University of O. Adjadi (Benin), National University of Benin Benin H. Adu-Dapaah (Ghana), University oflbadan, Nigeria T.P. Akonde (Benin), National University of Benin K.P. Atropo (Benin), National University of Benin Ndombo Delo (Zaire), University oflbadan, Nigeria H. Dossou Bata (Benin), National University of Benin Muyolo Gilumbu (Zaire), University oflbadan, Nigeria W.N.O. Hammond (Ghana), University of Ghana C.E. Gyansa-Ameyaw (Ghana), University of Ghana C.A. Soglo (Benin), National University of Benin Idumbo Kasele Nsongi (Zaire), University of Ibadan, Root and Tuber Improvement Program Nigeria Kiala Kilusi (Zaire), University oflbadan, Nigeria Collaborators: H.O. Nsiama She (Zaire), University oflbadan, Nigeria M. A-As-Saqui, agronomist and head, Division of Field Kasu Tombo (Zaire), University oflbadan, Nigeria Crops, CARl, Suakoko, Liberia A.A. Younous (Chad), University ofIbadan, Nigeria 214 Collaborators and Trainees Farming Systems Program E.T. Eshett (Nigeria), University ofIbadan, Nigeria H.F.K. Franzen (West Germany), University of Collaborators: Gottingen, West Germany G.O.1. Abalu, Department of Agricultural Economics and J.E.G. Ikeorgu (Nigeria), University ofTbadan, Nigeria .Hural Sociology, IAR, Zaria, Nigeria N.O. Iwuafor (Nigeria), Ahmadu Bello University, C. Agbokoba, director, Okomo/Udo Federal Oil Palm Nigeria Project, Nigeria B. Kayombo (Tanzania), University of Dar-es-Salaam, L. Ahialegbedzi, director,. Meterorological Services, Tanzania Lome, Togo C.A. Mba (Nigeria), Technical University of Berlin, West O. Babalola, soil scientist, Department of Agronomy, Germany University ofIbadan , Nigeria M.B. Niyungeko (Zaire), Faculty Institute of Agricultural M. de Boodt, soil physicist, University of Ghent, Belgium Sciences, Zaire R. Delogu, director, Okomo/Udo Federal Oil Palm Project, M.E. Ogula (Zaire), Faculty Institute of Agricultural Nigeria Sciences, Zaire J. de Wolf, ILRI, Wageningen, Netherlands L.T. Ogunremi (Nigeria), University ofIbadan, Nigeria M. Diomande, ORSTROM, Adiopodoume, Ivory Coast U. Sabel-Koschella (West Germany) , Technical W. Ehlers, soil scientist, University of Gottingen, West University of Munich, West Germany Germany N. Sanginga (Zaire), Faculty Institute of Agricultural T.A. Faseun, NIHORT, Ibadan, Nigeria Sciences, Zaire D. Gabriels. soil scientist, University of Ghent, Belgium S.B.C. Wanki (Cameroon), University ofIbadan, Nigeria A.Q. Gudugi, Bida ADP, Nigeria Wong Ting Fook (Mauritius), University of Reading, E.G. Hallsworth, IFIAS, University of Sussex, England England F.S. Idachaba, professor, Department of Agricultural C.F. Yamoah (Ghana), University ofIbadan, Nigeria Economics, University ofIbadan, Nigeri a A. Jibrin, Bida ADP, Nigeria Research Scholars: B. Kalabari , Shell Nigeria, Warri , Nigeria B.R. Ball (Canada) , University of Guelph, Canada A. Kogblevi, Centre National d'Agropedologie, Cotonou, A.R.S. Ibrahim (Ghana), University ofIbadan, Nigeria Benin A.E. Kraayeveld (Netherlands), Wageningen University, P.R. Maurya, soil scientists, IAR, ABU, Samaru, Nigeria Netherlands F.B. Ndubuka, Imo State/World Bank Small-Holder Rice D.M.J. Neirynck (Belgium), University of Leuven, Production Scheme, Nigeria Belgium M. Obaton, Laboratoire de Recherche sur les Symbiotes W.H. Sampers (Belgium), University of Ghent, Belgium des Racines, Montpellier, France J.E.M. van den Hengel (Netherlands), Wageningen O. Odeyemi, Department of Microbiology, University of University, Netherlands !fe, Nigeria M. van Uytvanck (Belgium)', University of Leuven, P. Odili, NTEJE, Nigeria Belgium C.T.1. Odu, microbiologist, Department of Agronomy, University ofIbadan, Nigeria Research Support Units S.O. Odurukwe, NRCRI, Umudike, Nigeria Collaborators: A. Ohiri, NRCRI, Umudike, Nigeria R.D. Smith, consultant to IBPGR, Royal Botanic Gardens, P. Ohuyon, Shell Nigeria, Warri Kew, England O. Ojo, professor, Department of Geography, University of Lagos, Nigeria Research Fellows: B.A. Olunuga, NCRI, Ibadan, Nigeria F.N. Anno-Nyako (Ghana), IITA Virology Unit, M.O. Omidiji, IAR&T, University ofIfe, Ibadan, Nigeria University of Science and Technology, Ghana J.A.1. Omueti, Department of Agronomy, University of M. Gumedzoe (,rogo), UTA Virology Unit, Laval Ibadan, Nigeria University, Belgium C.O. Oputa, FACU, Ibadan, Nigeria P. Reid, senior agronomist, Ilorin ADP, Nigeria Research Scholars: G. Rinaudo, Laboratoire de Biologie des Sols, ORSTROM, J. Janssens (Belgium), IITA Analytical Services, Dakar, Senegal University of Leuven, Belgium U. Schwertman, soil scientist, University of Munich, S . ..,Bologeoku (Nigeria), IITA Communications and West Germany . Information, University ofIbadan, Nigeria W. Shearer, program officer, UNU, Tokyo, Japan O. Famubode (Nigeria), lITA Communications and K. Smilde, Institute for Soil Fertility, Haren, Netherlands Information, University ofIbadan, Nigeria J. van der Heide, Institute for Soil Fertility, Haren, M'Bi B. Zagre (Benin), UTA Virology Unit, National Netherlands University of Benin 0.0. Vaughn, NCRI, Ibadan, Nigeria K. Vlassak, professor, University of Leuven, Belgium P.L.G. Vlek, IFDC, Muscle Shoals , Alabama A. Wild, professor, Department of Soil Science, University of Reading, England Research Fellows: M. Armon (Nigeria), University ofIbadan, Nigeria K. Attah Krah (Ghana), University of Ibadan, Nigeria B. Duguma (Ethiopia), University ofIbadan, Nigeria Publications 215 Publications Farming Systems Program Ezumah, H.C. 1983. Agronomic considerations of no­ Cereal Improvement Program tillage farming. In No-Tillage Crop Production in the Akibo-Betts, D.T., J.W. Gibbons, M.S. Alam and Y. Tropics. p. 102-110. Eds. 1.0. Akobundu and A.E. Efron. 1983. Aphids on rice roots. lITA Research Briefs Deutsch. Corvallis: International Plant Protection 4(1,2&3): 4-5. Center, Oregon State University. Alam, M.S., J.W. Gibbons, D.T. Akibo-Betts. K. Ezumah, H.C., cd. 1983. Cassava Production and Wasano, Kaung Zan and Y. Efron. 1983. Hopperburn Extension in Central Africa. IITA Proceedings Series, in rice caused by brown planthopper. UTA Research no. 4. Ibadan: IITA. Briefs 4(1.2&3): 6-7. Ezumah, H.C.,and V. Balasubramanian.1983. Possible Dabrowski, Z.T. 1983. ldentifying and collecting roles of farming systems research in reducing food Cicadulina for maize streak resistance screening. IITA production constraints of Rwanda. In Agricultural Research Briefs 4(4): 2-3. Research in Rwanda: Assessment and Perspectives, ed. lVI.J. Chang, p. 77-82. Government of Rwanda and ISNAR. Ezurnah, H.C., and D.L. Plucknett. 1982. Cultural Grain Legume Improvement Program studies on taro, Colocasia esculenta (L.) Schott. 2. Age and Jackai, L.E.N. 1983. Efficacy of insecticide applications at moisture effects on growth and corm yield. Journal of different times of day against the legume pod borer, Root Crops 8(1.2): 17-26. Maruca testulalis (Geyer) (Lepidoptera: Pyralidae) on Ghuman, B.S., and R. Lal. 1983. Effect of crop cover on cowpea in Nigeria. Prot. Ecol. 5: 245---25l. temperature regime of an Alfisol in the tropics. Agron. J. Jackai, L.E.N., and S.H. Singh. 1983. Suitability of 75: 931-936. selected leguminous plants for development of Maruca Ghuman, B.S., and R. Lal.1983. Growth and plant-water testulalis larvae. Ent. expo et appl. 34: 174-178. relations of sweet potato as affected bv soil moisture Jackai, L.E.N., and S.R. Singh. 1983. Varietal resistance regimes. Plant and Soil 70: 95·-106. - in the integrated pest management of cowpea pests. Ghuman, B.S., and R. Lal. 1983. Mulch and irrigation Insect &:i. Application 4: 1-2. effects on plant·water relations and performance of Kueneman, E.A. 1983. Genetic control of seed longevity cassava and sweet potato. Field Crops Res. 7: 13 29. in soybeans. Crop Sci. 23: 5-8. Kang, B.T. 1983. Fertilizer use in multiple cropping Price, M., B.B. Singh and C. Mamkwe. 1983. The role of systems in Nigeria. Tanzania and Senegal. In Fertilizer early maturing cowpea varieties in Tanzania. Trop. Use Under Multiple Cropping Systems. p. 36-45. FAO Grain Legume Bull. 27: 8-10. Fertilizer and Plant Nutrition Bulletin 5. Rome: FAO. Singh, B.B., and S.R. Singh. 1983. Objectives and Kang, B.T. 1983. Potassium and magnesium responses of achievements of the [ITA research programme on cow· cassava grown in an Ultisol in southern Nigeria. Ferl. peas and soybeans. In l\1ore Food From Better Technology. Res. In press. eds. J.e. Homes and VV.:\1. Tahir, p. 778 790. Rome: FAO. Kang, B.T., and A.D. Messan. 1983. Fertilizer manage· Singh, B.B., S.H. Singh and L.E.N. Jackai. 1983. ment for no-tillage crop production. In No-Tillage Crop Opportunities for expanding cowpea production in Production in the Tropics, p. 111-118. Eds. 1.0. Akobundu Rwanda. In Agricultural Research w Rwanda: and A.E. Deutsch. Corvallis: International Plant Assessment and Perspectives, ed. M.J. Chang, p. 139-141. Protection Center, Oregon State Universitv. Government of Rwanda and ISNAR.. Rang, B.T., and D. Nangju. 1983. Phosphorus response of Singh, S.H., B.B. Singh, L.E.N. Jackai and B.H. :-.Itare. cowpea, Vigna unguiculata (L.) \Valp. Tropical Grain 1983. COLLpea Research at IITA. IITA Information Series, Legume Bulletin 27: 11-16. no. 14. Ibadan: IITA. Lal, R. 1983. Effects of slope length on runoff from Alfisols in western Nigeria. Geoderma 31: 185-193. Lal, R. 1983. Erosion caused productivity decline in soils of the humid tropics. Soil Taxonomy Neu;s 5: 4·· 5, 18. Root and Tuber Improvement Program Lal, H., A.S.H. Juo and B.T. Kang. 1983. Chemical Badra, T., and F.E. Caveness. 1983. Effects of dosage approaches towards increasing water availability to sequence on the efficacy of non fumigant nematicides, crops including minimum tillage systems. In inter· plantain yields and nematode seasonal fluctuations as national conference proceedings entitled Chemistry and influenced by rainfall. Journal of Nematology 15. World Food Supplies: The New Frontiers. p. 57-77. Dahniya. M. T., S.K. Hahn and C.O. Oputa. 1983. Effects Manila: IHRI. of shoot removal on shoot and tuberous root yields and Lal, R., and J.O. Oluwole. 1983. Physical properties of yield components of sweet potato. Experimental earthworm casts and surface soil as influenced by Agriculture. In press. management. Soil Science 135: 114-123. Hahn, S.K., and Y. Hozyo. 1983. The physiology of sweet Mambani, B., and R. Lal. 1983. Response of upland rice potato. In The Physiology of Tropical Field Crops. varieties to drought stress. 1. Relation beh~ieen root Chichester: John Wiley and Sons. system development and leaf water potential. Plant and Hahn, S.K., and Y. Hozyo.1983. Sweet potato and yam. In Soil 73: .j9-72. Potential Productivity of Field Crops Under Difierent Mambani, B., and R. Lal. 1983. Response of upland rice Environments, p. 319-340. Los Banos: IRR1. varieties to drought stress. II. Screening rice varieties by Rao, P .V., and S.K. Hahn. 1983. An automated enzymatic means of variable moisture regime along a toposequence. assay for determining the cyanide content of cassava Plant and Soil 73: 73-94. C.~anihot esculenta) and cassava products. Journal of the Science of Food and Agriculture. In press. 216 Conference Papers Mambani, B., and R. Lai. 1983. Response of upland rice Kueneman, E.A. 1983. Requirements for accelerating varieties to drought stress. III. Estimating root system soybean production in Nigeria : a look at the past and configuration from soil moisture data. Plant and Soil 73 : projections for the future .. Paper presented at the Third 95 104. Annual Meeting of the Nigerian Soybean Scientists, 7- 9 Mbagwu, J., R. Lal and T.W. Scott. 1983. Physical February 1983, Makurdi, Nigeria. properties of three soils in southern Nigeri a. Soil Science Kueneman, E.A., and W.R. Root. 1983. Highlights of 135: 114- 122. ::ioybean research at IITA in 1982. Paper presented at the Third Annual Meeting of the Nigerian Soybean Virology Unit Sci(~nt.ist.s. 7 9 F(~hruury 19R~, Makurdi, Nigeria. Anno-Nyako, F.O., H.J. Vetten, D.J. Allen and G . Thottappilly. 1983. The relation between cowpea golden Root and Tuber Improvement Program mosaic and its vector, Bemisia tabaci. Ann. appl. 102: 319- 323. Caveness, F.E. 1983. Cassava storage root yield losses Rossel, H. W., G. Thottappilly, and I. W. Buddenhagen .. from root-knot nematode (Meloidogyne incognita race 2 1982. Occurrence of rice yellow mottle virus in two and M.javanica) parasitism. Paper presented at the Sixth important rice growing areas of Nigeria. FAG Plant Symposium of the International Society for Tropical Protection Bulletin 31: 137- 139. Root Crops, 21- 26 February 1983, CIP, Lima, Peru. Caveness, F.E., S.K. Hahn and M.N. Alvarez. 1983. Genetic Resources Unit Description of crops: sweet potato, yam and coco yam. Paper presented at the Global Workshop on Root and Ng, N.G., M. Jacquot, A. Abifarin, K. Goli and K. Tuber Crops Propagation. 12- 16 September 1983, CIAT, Miezan. 1983. Rice genetic resources collection and Cali, Colombia. conservation activities in Africa ·· the programs of rITA . Hahn, S.K. 1983. Progress of root and tuber improvement WARDA, IRAT and ORSTROM. In Proceedinf!s of the at IITA. Paper presented at the Sixth Symposium of the 1983 Rice Germplasm Conservation Workshop, p. 45-·52. International Society for Tropical Root Crops, 21 - 26 Los Banos: IRRI and IBPGR. February 1983, CIP, Lima, Peru. Hahn, S.K., M.N. Alvarez, F.E. Caveness and S.Y. Ng. Library and Documentation Center 1983. Sweet potato improvement at IITA. Paper pre· lbekwe, G.O. 1982. Libraries in Oyo State: still hoping for sented at the Caribbean Regional Workshop on Tropical the best. Library Forum 1(1): 4- 8. Root Crops. 10- 16 April 1983. University of the West Lawani, S.M. 1982. On the relationship between quantity Indies, Kingston, Jamaica. and quality of a country's research productivity. J ournal Hahn, S.K., N.M. Mahungu, E.M. Chukwuma, P.V. of Information Science 5(4): 143-145. Rao and A.M. Almazan. 1983. Breeding low cyanide Lawani, S.M., and A.E. Bayer. 1983. Validity of citation cassava varieties and effect of traditional processing criteria for assessing the influence of scientific publi· methods on the residual cyanide content in the final cations: new evidence with peer assessment. Journal of products. Paper presented at the First African the American Society for Information Science 34(1): 59- 66 .. Conference of Food Science and Technology, 14- 17 November 1983, Cairo, Egypt. Conference and Seminar Herren, H.R. 1983. The cassa va mealybug and green spider mite problem and the biological control approach to Papers solve it. Paper presented at the Annual Meeting of the Entomological Society of America, 2-5 December 1983, Detroit, Michigan. Cereal Improvement Program Herren, H.R. 1983. The Africa-wide biological control Efron, Y. 1983. Development of high yielding stable maize programme of cassava mealybug and green spider mites : varieties with emphasis on resistance to maize streak achievements and control strategies. Paper presented at virus through international cooperation. Paper pre­ the USAlD Regional Meeting, 7- 11 December 1983, sented at the seminar Agricultural Research in Rwanda: Harare, Zimbabwe. Assessment and Perspectives, 5-12 February 1983, Herren, H.R., and T.L. Lawson. 1983. The Africa-wide Kigali, Rwanda. programm«;! for biological control of the cassava mealy­ bug and green spider mit.es : the importance of thorough Grain Legume Improvement Program foreign exploration for beneficial insects and mites . Paper presented at the Third Brazilian Cassava Dashiell, K.E., E.A. Kueneman, W.R. Root and S.R. Congress, 7-11 November 1983, Brasilia, Brazil. Singh. 1983. Breeding tropical soybeans for superior Herren, H.R., K.M. Lema and P. Neuenschwander. seed longevity and for nodulation with indigenous rhizo­ 1983. Biological control of the mealybug, Phenacoccus bia. Paper presented at the International Symposium on manihoti , and the green spider mite complex, Soybean, 26 September-1 October 1983, Tsokoba, Japan. Mononychellus spp., on cassava, Manihot esculenta, in Jackai, L.E.N. 1983. Feeding behavior of pod bugs: impli­ Africa. Paper presented at the Tenth International Plant cations for host plant resistance studies. Paper presented Protection Congress, 20-25 November 1983, Brighton, at the International Congress of Plant Protection, 20- 25 England . • November 1983, Brighton, England. Lema, K.M., R.D. Hennessey and H.R. Herren. 1983. Jackai, L.E.N. 1983. Cultural control of insect pests of The mealybug front hypothesis: possible role of in­ tropical grain legumes: use of trap crops. Paper pre­ digenous natural enemies. Paper presented at the Second sented at the International Workshop on Integrated Pest Triennial Symposium of the International Society for Control for Grain Legumes, 4- 9 April 1983, Goiania, Tropical Root Crops-Africa Branch, 14- 19 August, 1983, Brazil. Douala, Cameroon. Conference Papers 217 Lema, K.M., and N .M. Mahungu. 1983. Effect offertilizer Expert Meeting on Guidelines for the Role of Farming application on the. development and reproduction of the Systems in Preventing Soil Degradation, 20- 24 June, cassava mealybug. Paper presented at the Second ICRISAT, Hyderabad, India. .T riennial Symposium of the International Society for Wilson, G.F. 1983. Plantain research in West Africa . Tropical Root Crops-Africa Branch, 14- 19 August, 1983, Paper presented at the Workshop on Banana Production Douala, Cameroon. and Research in Central and Eastern Africa, Bujumbura, Ng, S.Y. 1983. The application of plant tissue culture for Burundi, 14- 17 December, 1983. the distribution and conservation of cassava and sweet potato. Paper presented at the symposium on Tissue International Programs Culture of Economically Important Plants, 28 August- 2 Hahn, S.K., E.R. Terry and N.C. Russell. 1983. The September 1983, University of Nigeria, Nsukka, Nigeria. impact of biotechnology on food production in Africa: Ng, S. Y. 1983. Tissue culture of cocoyams. Paper presented The Cassava Story. Paper submitted at ajoint meeting on at the symposium on Tissue Culture of Economically international cooperation for African technological Important Plants, 28 August-2 September 1983, development, 5-7 December 1983, Dakar, Senegal. University of Nigeria, Nsukka, Nigeria . Lawson, T.L., and E.R. Terry. 1983. Weather and plant Ng, S. Y. 1983. Special techniques assist in quality seed diseases in Africa. Paper presented at the conference production of sweet potato, yam and cocoyam. Paper Advancing Agricultural Production in Africa. 12- 18 presented at the Global Workshop on Root and Tuber February 1984, Arusha, Tanzania. Crops Propagation, 12-16 September 1983, CIAT, Cali, Terry, E.R. and D. Perreaux. 1983. Cassava diseuses. Colombia. their spread and control. Paper presented at the con· ference Advancing Agricultural Production in Africa . Farming Systems Program 12- 18 February, Arusha, Tanzania. A Y, P. 1983. Basic socioeconomic data as a frame for Virology Unit preparation of on-farm research. Paper presented at an on-farm research training workshop, 7- 18 March 1983, Rossel, H.W., G. Thottappilly and F.O. Anno-Nyako. IITA. 1983. Soybean "dwarf" in Nigeria, a whitefly-transmitted Ay, P. 1983. Problems and constraints of group production disease of high risk potential. Paper presented at the in tropical agriculture. Paper presented at a workshop Third Annual Meeting of the Nigerian Soybean entitled "The Responsiveness of the Nigerian Coopera­ Scientists , 7- 9 February 1983, Makurdi, Nigeria. tive Movement, the Challenge of the Green Revolution," August 1983, University of Nigeria, Nsukka. Ay, P. 1983. Research planning and integration of farmers Library and Documentation Center in priority decisions for development. Paper presented at Lawani, S.M. 1983. Database searching and database the Twelfth European Congress for Rural Sociology, development in Nigeria. Paper prepared for the Second . ';. . 24- 30 July 1983, Budapest, Hungary. Training Course in Computerized Information and Juo, A.S.R., J .M. Barret and A.A. Dabiri. 1983. Surface Documentation Systems, 14-19 February 1983, Federal reactivity of oxidic minerals in tropical soils. Paper Institute of Industrial Research, Oshodi, Nigeria. presented at the American Society of Agronomy meeting, Lawani, S.M. 1983. Development of computerized infor­ 14- 19 August 1983, Washington, D.C. mation and documentation systems in Nigeria- some Lal, R. 1983. Soil conservation techniques in Nigeria. practical considerations. Paper prepared for the Second Paper presented at the First National Tillage Sym­ Training Course in Computerized Information and posium, 21-23 November 1983. Ilorin. Nigeria. Documentation Systems, 14~19 February 1983, Federal Lal, R., B.S. Ghuman and H.O. Maduakor. 1983. Effects Institute ofIndustrial Research, Oshodi, Nigeria. of soil moisture, bulk density and tillage methods on Lawani, S.M. 1983. Cumulative advantage in our pro· tropical root crops. Paper presented at the Sixth fessions and in our lives. Text of the Second Annual Symposium of the International Society for Tropical Lihrary Week L(~ct.ure, 10 Novemh(~r lm,:I. Universit.y of' Root Crops, 21-26 February 1983, CIP, Lima, Peru. lbadan, Nigeria. Mulongoy, K. 1983. Field decomposition of leaves of Psophocarpus palustris and Gliricidia sepium in an Alfisol as affected by thiodan and benomyl. Paper pre­ sented at a joint meeting of tlJe British Society of Soil Science and Commissions III and IV ofthe International Society of Soil Science on Biological Processes and Soil Fertility, 4-8 July 1983, Reading University, England. Mulongoy, K., and A. Ayanaba. 1983. Variation of the population sizes of cowpea and soybean rhizobia at three locations in West Africa. In Proceedings of the Thirteenth International Congress of Microbiology, Boston . Mutsaers, H.J. W. 1983. Concepts of on-farm adaptive research. Paper presented at the First Workshop of the On-Farm Research in Ivory Coast Project. 15- 17 December 198~, Ivory Coast. 1'er Kuile, C.H.H., and B.T. Kang. 1983. Guidelines for farming systems to prevent soil degradation in the humid and subhumid tropics. Paper presented at the UNDP 218 Acronyms Acronyms used in this publication: IFDC, International Fertilizer Development Center, United States. ABCP, Africa·wide Biological Control Programme of IFIAS, International Federation of Institutes for Cassava Mealybug and Green Spider Mites, Advanced Studies, England. Nigeria. ILRI, International Institute for Land Reclamation ABU, Ahmadu Bello University, Kigeria. and Improvement, Netherlands. ADP, Agricultural Development Project (supported INTSOY, International Soybean Program, United by tbe World Bank). States. AGCD, Administration Generale de la Cooperation IPO, Research Institute for Plant Protection, au Development (General Administration for Netherlands. Cooperation and Development), Belgium. IRA, Institut de la Recherche Agronomique BKAWIKORD, Bundeskanzleramt Wirtschaftliche (Institute for Agricultural Research), Cameroon. Koordination und Verstaalichte Unternehmungen IRAT, Institut de Recherches Agronomiques (Federal Chancellory for Economic Coordination Tropical (Institute for Tropical Agricultural and State·Owned Enterprizes), Austria. Research), France. CARl, Central Agricultural Research Institute, IRRI, International Rice Research Institute, Liberia. Philippines. CGIAR, Consultative Group on International IRTP, International Rice Testing Program. Agricultural Research. ISAR.. Institut de Sciences Agricoles du Rwanda CIAT , Centro Internacional de Agricultura Tropical (Rwandan Institute of Agricultural Sciences). (International Center for Tropical Agriculture), JICA, Japanese International Cooperation Agency. Colombia. KARl, Kenyan Agricultural Research Institute. CIBC, Commonwealth Institute of Biological KIT, Royal Tropical Institute, Netherlands. Control, England. LWDD, Land and Water Development Division, CIDA, Canadian International Development Ministry of Agriculture and Forestry, Freetown, Agency. Sierra Leone. CIMMYT, Centro Internacional de Majoramientode NAFPP, National Accelerated Food Production Maiz y Trigo (International Center for Maize and Proj ect, Nigeria. Wheat Improvement), Mexico. NCRE, Kational Cereals Research and Extension CIP, Centro Internacional de la Papa (International Project, Cameroon. Potato Center), Peru. NCRI, Kational Cereals Research Institute, Nigeria. CNPAF, National Center for Research on Rice and NGPC, National Grains Production Company, Beans, Brazil. Nigeria. CNRCIP, Cameroon National Root Crop NIHORT, National Institute for Horticultural Improvement Program. Research, Nigeria. DCA, Directorate for Technical Development and NRCRI, National Root Crops Research Institute, Humanitarian Aid, Switzerland. Nigeria. EEC, European Economic Community. ODM, Overseas Development Ministry ofthe United EMBRAPA, Empressa Brasiliera de Pesquina Kingdom. Agropecuaria (National Agricultural Research OFAR, On·farm adaptive research. Organization of Brazil). ORSTROM, Office de la Recherche Scientifique et FACU, Federal Agricultural Coordinating Unit, Technique Outre·Mer (Overseas Agency for Nigeria. Scientific and Technological Research), France. FAO, Food and Agriculture Organization. Oxfam, Oxford Committee for Famine Relief, GTZ, Deutsche Gesellschaft fur Technische England. Zusammenarbeit (German Agency for Technical PRONAM, Programme National du Manioc Cooperation). (N ational Manioc Program), Zaire. IAR, Institute of Agricultural Research, Nigeria. RNRCIP, Rwandan National Root Crops IAR&T, Institute of Agricultural Research and Improvement Program. Training, Nigeria. SAFGRAD, Semi·Arid Food Grains Research and IBPGR, International Board for Plant Genetic Development Project, Upper Volta. Resources, Italy. STIBOKA, Soil Survey Institute, Netherlands. ICI, Imperial Chemical Industries, England. TLU, Testing and Liaison Unit, NCRE, Cameroon. IDA, International Development Association, World UNDP, United Nations Development Programme. Bank. UNU, United Nations University. IDRC, International Development Research Centre, USAID, United States Agency for International Canada. Development. IFAD, International Fund for Agricultural WARCORP, West Afric,an Regional Cooperative for Development. Research on Plantain. IFARD, International Federation of Agricultural WARDA, West African Rice Development Research Systems for Development. Association, Liberia.