On the cover ..... Agroforestry research at IITA focuses on alley farming - the growing of food crops such as cowpea between hedgerows of trees or shrubs. Here, IT 82£ 60, a variety of cowpea that mallires in 60 days, is grown between rows ofLeucaena leucocephala, a species of leguminous tree that fixes nitrogen in the soil. Many food crops can be grown in lhese tree-based systems which have the potential to become slable, low-input alternatives to the traditional systems of shifting cultivation-systems tirat can no longer sustain agricultural production at the levels now needed in Africa. Published by International Institute o f Tropical Agriculture PMB 5320, Oyo Road, Ibadan, Nigeria (June (987) 996L Contents I Introduction to liTA 4 Board of Trustees S What is the Consultative Group on International Agricultural Research (CGIAR)? 7 Director General's Report Focus 13 Developing strong national research capabilities in Africa: Real progress in Cameroon 18 Research achievement on Maize Streak Virus wins King Baudouin A ward Resource and Crop Management Program 23 Annual Report Executive Summary 27 Nitrogen contribution of hedgerow trees in alley cropping systems 29 Calliandra calothyrsus: a promising tree/or alley cropping systems 31 Weeding requirement in alternate-year maize production in alley cropping with Leucaena leucocephala 33 Alley cropping and soil erosion control 34 Performance of leguminous shrubs in alley cropping trials at Kagasa, Rwanda 36 On-farm trials 0/ upland crops in rice faliows 38 Prospects for improved upland rice production in southwestern Nigeria 40 Effects of deforestation and land use 42 Critical calcium and acidity levels established/or maize Grain Legume Improvement Program 44 Annual Report Executive Summary 46 Cowpea plant architecture and legume pod borer damage 49 Breeding for multiple disease and insect resistance in cowpea 51 Screening cowpeas for resistance to Maruca pod borer stem damage S3 Cowpea pests in on-farm trials under mixed cropping systemt S4 Effects 0/ crop residues and tillage methods on cowpea production in Sudan savanna S6 An effective new method for screening soybeans for resistance to frog-eye leaf spot (Cercospora sojina) 58 A laboratory methodforevaluating resistance to pod shattering in soybeans ii Maize Research Program 60 Annual Report Executive Summary 63 Maize with combined resistance to downy mildew and maize slreak virus available to farmers 65 Synthetic maize varieties developed 67 Maize streak virus screening methodologies for the mid-altitude ecology 69 Biological control of aphids in leafhopper-rearing cages 71 Inbred lines as uniform genetic sources of resistance 73 Screening and breeding for resistance to Eldana saccharina 75 Inbred lines tolerant to drought identified Rice Research Program 77 Annual Report Executive Summary 80 llTA elite rice varieties recommended to Nigerian farmers 82 Reducing toxicity of iron to rice plants 84 Oryza glaberrima as a source of resistance to rice yellow mottle virus 86 Rice lines resistant to pink stem borer identified 87 Silica and magnesium application reduces grain discoloration in upland rice 88 The effectiveness off lash tapes in protecting rice fields from grain-eating birds Root and Tuber Improvement Program 89 Annual Report Executive Summary 91 TMS 4(2)1425 is the outstanding variety in 3-year cassava trials 93 Cassava-groundnut intercropping has potential to increase the nutritional quality of the diet in Zaire 96 Elite cassava clones assessed for gari quality 98 Cassava chips offer real potentialfor utilization in Africa 101 Prolonging dormancy ofy am tubers through the use ofg ibberellic acid (GA JJ 103 A production system for medium-sized seed yams 105 Realizing maximum tuber yields ofy ams (Dioscorea sp.) gro wn from minisells Africa-wide Biological Control Project 106 A strategy to initiate and develop national biological control programs (NBCPs) in Africa 109 The impact of cassava green mites on cassava yields 112 Strategies for classical biological control of cassava green mites iii 115 Update on release, establishment, and impact ofEpidinocarsis lopezi and other natural enemies of the cassava mealybug 119 Exploration for natural enemies ofc assava mealybug and cassava green mites 121 Virology Unit 125 Comparative studies on sweet potato virus complexes worldwide 127 Cowpea mild mottle virus (CMMV) is not seed-borne in soybean 128 International Cooperation and Training Program 134 Documentation, Information, and LibrQlY Program 138 Genetic Resources Unit 140 Roster of Long-serving Personnel 142 List of Principal Staff 145 Collaborators, Research Fellows, and Research Scholars 149 Publications iv Introduction to IITA Established in July 1967 as the first major African link in an integrated network of interna­ tional research and training centers located throughout the developing regions of the world, the International Institute of Tropical Agriculture (UTA) is an autonomous, nonprofit corporation with headquarters on a I,DOO-hectare experimental farm at Ibadan, Nigeria. Its location facilitates research in three ecological zones - humid forest, transitional, and savanna - representative of climate and soil conditions in many areas of Africa. In addition, research is conducted in many areas of Africa in cooperation with regional and national programs. Funding for UTA came initially from the Ford and Rockefeller foundations, and the land for the experimental farm was allotted by the Government of the Federal Republic of Nigeria. The Institute is governed by a Board of Trustees comprised of 15 members, including eminent scien­ tists and representatives from the host country, African tropical areas, and other regions of the world. (The names and affiliations of Board members are listed on page 4). Mandate and Objectives: The "geographic mandate" of UTA includes the humid and subhumid tropical regions of the world, but the Institute concentrates its research and training activities primarily on the needs of sub-Saharan African countries. The central objective, in cooperation with national pro­ grams, is to undertake research which will make it possible to increase food production, employment, and income in those countries. A food crisis in many of them has been building up over the years as rapid population growth, drought, and lagging agricultural production have brought about a chronic food deficit. Four out of five of the research programs of UTA are crop centered: Grain Legume Improve­ ment, Maize Research, Rice Research, and Root and Tuber Improvement. The fifth is the Resource and Crop Management Program. Specifically, the objectives of these and other segments of the Institute are to: • Develop farming systems, including soil and crop management practices, that will provide viable, stable, and sustainable alternatives to traditional systems of shifting cultivation in Africa; the major emphasis centers on increasing the productivity of fragile tropical soils while still maintaining effective conservation in ecologically balanced environments. • Develop and implement research programs which will lead to improved varieties of cowpeas, yams, and sweet potatoes. • Conduct research in Africa in cooperation with other international centers and national in­ stitutes, to develop and improve cassava, maize, rice, soybeans, plantain, and cocoyams; here the practical emphasis is on the distribution of improved plant materials to national research programs to assist them with their plant breeding work and the adaptation of im­ proved varieties to fit local conditions. • Transfer new technologies and skills, through training, to scientists, technicians, and exten­ sion workers from developing countries. • Arrange and conduct conferences, symposia. seminars, and workshops to review new research, consider current problems, and discuss needs for the future. • Publish and widely disseminate research findings to scientists, policy makers, national research programs, development and extension personnel, and others. • Provide an information center and library with a comprehensive collection of world literature on tropical agriculture for use by scientists and scholars. Funding: Principal financing is arranged through the Consultative Group on International Agricultural Research (CGIAR). (See Information on CGIAR beginning on page 5). Financial support for the core program during 1986 was provided by: Australia. Austria, Belgium, Canada, China, Denmark, Federal Republic of Germany, The Ford Foundation, France, India, Italy, Japan, The Netherlands, Nigeria, Norway, Private Assistance in International Development, Sweden, The Rockefeller Foundation, The United Kingdom, United Nations Development Program, United States Agency for International Development, and theWorld Bank. In addition, the following organizations and governments also provided funds for special pro­ jects and specific training activities: African Development Bank, Belgium, Canadian Interna­ tional Development Agency, Commission of the European Communities in Nigeria, Gatsby Charitable Foundation, Federal Republic of Germany, The Ford Foundation, International Development Research Centre, International Fund for Agricultural Development, Italy, Nigeria, United Nations University, United States Agency for International Development, Union Carbide Corporation, University of Hohenheim, and the World Bank. Staff: The Institute has nearly 200 principal staff members who come from more than 40 countries. lITA also employs over 1,000 support staff, most of whom are from Nigeria. The majority of the Institute's scientists are located at headquarters but some have been assigned to IITA substations at Onne (Nigeria) and at Cotonou (Republic of Benin) and to projects in collabora­ tion with regional and national programs. (See the Annual Report Executive Summary of the International Cooperation and Training Program beginning on page 128). 2 INTERNATIONAL INSTITUTE OF TROPICAL AGRICULTURE BOARD OF TRUSTEES AND INSTITUTE DIRECTORS MAY 1987 Standing , left to ,;ght Dunstan Spencer, Staff; Hugh Popenoe. Observer (USAID); William St8ele. Staff; John Seymour-Griffin. Staff; Kenneth Fischer. Staff; Stephen lawani. Staff; Randolph Barker, Trustee; Sang Ki Hahn. Staff ; Curtis Farrar. Observer (CGIAR Secretariat ); Sheriff Adetunji, Trustee; Eugene Terry . Staff; Kunia Toriyama, Trustee; Bede Okigbo. Staff; Chimera Ikaku. Trustee; Heinz Gasser. Staff; Klaus Lampe. Trustee: Thea Wormer. Trustee; Yoel Efron . Staff; John Davies, Staff; Shiv Singh. Staff; John Lowe. Staff; William Furtick. Observer (USAID). Sitting. left to right Laurence Stife!, Director General; Mowbray Nicholas. Trustee; Mayrs Buvinic. Trustee; Edmond de Langhe. Trustee; John McKelvey, Jr., Chairperson; Nicholas Mumba. Trustee; Alhaji Gobir. Trustee; Lawrence Wilson . Chairperson-Designate; Leopold Fakambi . Trustee. Not Shown : Luis Crouc h , Trustee; Michael Akintomide. Staff; John Craig. Staff; and David McDonald . Staff . Board of Trustees Dr. John J. McKelvey, Jr. (Chairman) Dr. Klaus J. Lampe Rockefeller Foundation (Retired) Head. Department of Agriculture and Rural Richfield Springs. New York, U.S.A. Development German Agency for Technical Cooperation Mr. D.E. Iyamabo (Vice-Chairman)* Eschborn, West Germany Coordinating Director (Retired) Federal Ministry of Science and Technology Dr. Edmond de Langhe Lagos, Nigeria Director, International Network for Improvement of Banana and pJantain Prof. Ango Abdullahi* Montpellier, France Vice-Chancellor (Retired), Ahmadu Bello University Zaria. Nigeria Dr, Nkholas E. Mumba Director of Agriculture Dr. Sheriff A. Adetunji Lusaka, Zambia Director, Agricultural Sciences Department Federal Ministry of Science and Technology Mr. M.S.O. Nicholas Lagos, Nigeria. Director. Agricultural Services Division Food and Agriculture Organization Dr. Mayra Buvinic Rome, Italy Director. International Center for Research on Women Dr. Laurence D. Stife! Washington D.C., U.S.A. Director General, IITA Ibadan, Nigeria Dr. Luis Crouch Businessman Dr. Kunio Toriyama Santo Domingo, Dominican Republic Consultant, National Federation of Agricultural Cooperative Associations Mr. John D. Edozien Matsuga-oka, Kugenuma Permanent Secretary, Federal Ministry of Fujisawa, Japan Agriculture. Water Resources and Rural Development, Prof. Lawrence A. Wilson Lagos, Nigeria Faculty of Agriculture University of the West Indies Dr. Leopold K. Fakambi S1. Augustine. Trinidad Executive Secretary, lnternarional Federation of Agricultural Research Systems for Development; Prof. Theo M. Wormer Africa, Cotonou, Republic of Benin Professor of Tropical Botany (Retired) University of Amsterdam Prof. Chimere Ikoku EP Muiden, The Netherlands Vice-Chancellor. Cniversity of Nigeria Nsukka, ~igerja Dr. Hidetsugu lshikura'" Director GeneraJ, Japan Plant Protection • Term expired during the year Association Tokyo,Japan 4 What is the Consultative Group on International Agricultural Research (CGIAR)? At the initiative of the World Bank, the United Nations Food and Agriculture Organization (FAO), and the United Nations Development Programme (UNDP) , an informal association of governments, international and regional organizations, and private foundations was set up in 1971 dedicated to supporting a system of agricultural research centers around the world. It was named the Consul tative Group on International Agricultural Research (CG IAR) . The purpose of the research effort of 13 centers (including IITA) now in the CG IAR system is to improve the quantity and quality of food production and the standard of living of people in developing countries (Figure I). They focus their research efforts on crops and animals which provide a large part of the food supply of their respective regions . The international centers have a variety of research interests. Eight concentrate on plant breeding for one or more crops . Nine are involved in agronomic research , two deal with livestock, and two include major programs aimed at improving pastures Figure I. Global location of Ihe 13 CGIAR-supported international research and training centers. Centro Internacional de Agricultura Tropical (CIAT); Centro Im ernaciona l de 1a Papa (CIP); Centro Inlcrnacional de Mejoramienlo de Maiz y Trigo (CIMMYT); International Board for Plant Genetic Resources (lBPGR); International Center for Agricultural Research in the Dry Areas (ICARDA); International Crops Research Institute for the Semi-Arid Tropics (lCRISAT); Internat ional Food Policy Research Institute (lFPRI) ; International Institute of Tropical Agriculture (UTA); International Laboratory for Research on Animal Diseases (ILRAD): International Livestock Cen­ ter for Africa (ILeA); Inlcrnational Rice Research Institutc (IRRI); International Service for National Agricultural Research (ISNAR); West Africa Rice Devc!opmenl Association (WA RDA). 5 and forage crops. One center, IBPGR, devotes itself exclusively to the collection and conserva­ tion of genetic material; another, ISNAR, works with agricultural research agencies in develop­ ing countries to provide advice to governments on ways to strengthen agricultural research, and a third, IFPRI, studies the economics of food production to offer recommendations concerning policy changes needed to promote adequate and sustained growth. All the centers work closely with national agencies. The linkage is vital to keep the work at centers oriented to the needs of the farming communities they are intended to serve. In fact, the gains made by scientists at the centers will get translated into actual food output only when the national agencies take up the results, adapt them to local conditions, and carry them to their farmers. This is why great importance is attached to training programs. To date, the centers have trained more than 18,000 persons, mainly from developing countries. Each CGIAR-affiliated center is autonomous and run by an independent Board of Trustees on which members, chosen for their experience and expertise. serve in individual capacities. The board determines the direction of the center's research, but this is done in the framework of in­ ternational consultations on two levels-one scientific and the other financial and ad­ ministrative. The CGIAR, which has an executive secretariat provided by the World Bank, meets twice a year to take decisions based on consensus. The meetings have before them recommendations from a Technical Advisory Commit­ tee (TAC) comprised of a chairman and 14 distinguished scientists drawn from devel­ oped and developing countries. TAC is supported by a secretariat provided by the three co­ sponsors of CGIAR and located in Rome at FAO headquarters. Also available to the semi­ annual meetings are reports from centers, supporting bodies, and ad hoc committees that are set up from time to time to address specific issues. Raising of funds to support the work of the centers is coordinated by the CGIAR secretariat based in Washington. Funds are not pooled but go directly to individual centers. The bulk of the funding is not task-specific although some grants are earmarked for specific programs and activities within the broad framework defined by the CGIAR at its meetings. The CGIAR secretariat monitors the management performance of the centers, in keeping with the concept of accountability to donors, and provides overall administrative and management support. T AC monitors the scientific performance of the centers and reviews center budgets in the light of defined research priorities. CGIAR started operations with 15 donor members but by the beginning of 1986 that number had increased to 43 countries, international and regional agencies, and private founda­ tions. They pledged approximately U.S.S. 192 million to support the research and training programs of the 13 centers in 1986. 6 Director General's Report Historical Perspective As a result of a proposal from the Ford and Maize - Maize scientists prod uced varieties Rockefeller foundations, the Federal resistant to lowland tropical rust and blight, Military Government of Nigeria by decree and - most recently - maize streak virus. No. 32 created the International Institute of With Nigerian government support, IlTA Tropical Agriculture (UTA) on July 24, created hybrid maize technology for the 1967. On this 20th anniversary of UTA, I lowland tropics. For scientific excellence the want to reflect briefly on the historical ac­ Maize Program received the 1986 King complishments of the past before looking Baudouin Award for International forward in the life of the Institute. My Agricultural Research (See Focus article in predecessors assembled teams of scientists this volume) and honorable mention in the here at UTA and stimulated them to high 1986 development technology competition levels of creativity that made this truly a organized by the Italian International center of scientific excellence. liTA is not Cultural Center for the Development of always accorded due recognition for the Peoples. remarkable extent to which its scientists have Rice - /ITA varieties have been released unlocked the potential of key food crops for that have high yield potential and resistance African farmers. Some of the highlights are to blast. summarized here. Resource Management - IITA soil scien­ Cassava - lITA scientists developed com­ tists significantly increased knowledge of the bined resistance to the two major African physical, chemical, and biological properties diseases, cassava mosaic disease and cassava of African soils, providing a basis for the bacterial blight, thus providing a basis for development of systems of high and sus· research to increase yields in a broad range tainable agricultural production. Promising of ecologies. Moreover, lITA's Biological new technologies include ecologically sound Control Project, the largest in the world, has methods of land clearing, minimum tillage scored dramatic successes in controlling the cultivation, and alley cropping. insect pest, the cassava mealybug; this pro­ These and other accomplishments reflect ject recently received the Parasitis '86 the creativity and commitment of the staff, Award, and economists estimated its past and present, to the mission of the in· benefit·cost ratio as 200; I! stitute. On the occasion of this 20th anniver­ Cowpeas - UTA research produced sary, I salute them, especially the 152 in­ varieties with resistance to most major dividuals who have served the Institute for African diseases, moderate resistance to cer~ IS years or more and whose names are listed tain damaging pests, improved plant types, in this volume. and superior economic performance. lIT A has also been fortunate in having Soybeans - lIT A breeders removed the two had highly dedicated Trustees, coming from serious obstacles to soybean production in varied backgrounds but united by their pro· Africa, poor seed longevity and the need for found humanitarian concern and vision of a artificial inoculation with rhizobial bacteria, better world. Successive chairpersons were thereby making available to African individuals of great distinction; Will M. smallholders the means to produce a high­ Myers (1968-71), Forrest ("Frosty") Hill protein food crop with minimal investment. (1971·72), Bukar Shaib (1973·76), Thomas 7 R. Odhiambo (1976-77), A. Hugh Bunting phasis in the objectives of !ITA's commodi­ (1978-80), Guy Vallaeys (1980-83), and John ty research programs. Significant resources J. McKelvey, Jr. (1983-87). [ also take this can now be shifted toward breeding for occasion to pay tribute and express apprecia­ adaptation to key agro-ecologies, based tion to my predecessors: Herbert R. upon improved understanding of the major Albrecht (1968-75), William K. Gamble constraints and farming systems in each (1975-80), and Ermond H. Hartmans zone. Success generally is slower and more (1980-85). difficult to achieve in breeding for resistance lITA's achievements are, of course, to insect pests than in breeding for resistance directly attributable to the confidence and to disease, and this will require more exten­ generosity of donors within and outside the sive collaboration with advanced research Consultative Group on International centers for basic studies on the pests and Agricultural Research. I am pleased to note mechanisms for resistance to them. that Nigeria was the first host country to When I joined !ITA in late 1985 it seemed become a donor member of the CGIAR, and clear that !ITA's present and projected deep appreciation is due to successive resources would be insufficient to sustain the Nigerian Governments for- unstinting sup­ past research agenda and to move in these port over the years. urgent new directions. UTA was conducting research on nine commodities and was seek­ Need for Greater Program Focus ing sustainable farming systems to replace the bush·fallow system characteristic of On this 20th anniversary my colleagues and I most of the subhumid and humid tropics of have much of which to be proud. But if Africa. There was general agreement that !ITA's next two decades are to be as produc­ liT A needed sharper program focus and tive as its first two decades, future strategies concentration on critical problems - both must be designed to build upon the singular within and between research programs - if achievements of the past. The nature and -it was to continue to make the impact so pace of !ITA's progress and the rapidly acutely needed in Africa. changing African scene made strategic plan­ !ITA consequently conducted a Strategic ning an urgent and imperative task in 1986. Planning Study in 1986 that has led to a new At the time !ITA was established, it was agenda of program priorities and future apparent that commodity research could strategies to the year 2000 and beyond. have the greatest and most immediate impact !ITA's comprehensive strategic plan for the by developing germplasm with resistance to future will be released soon in a separate major African pathogens for national publication, but this Report provides me op· agricultural research systems. With access to portunity to convey its salient conclusions. diverse genetic resources and sophisticated support services, !ITA scientists realized the successes noted earlier. Furthermore, much Program Goals, Strategies and Priorities of this work could be effectively conducted I. Program Goals - !ITA conducts inter­ at the Ibadan headquarters because the national agricultural research and training primary aim was accumulating heritable activities within the limits of its formal man­ resistances rather than adaptation to defined date so as to contribute to increasing sus­ ecologies and farming systems. tainable food production in the humid and While much remains to be done in sub humid tropics and thereby to improve the resistance breeding, especially to protect past well being of low·income people. Our gains against mutant strains of pathogens, primary goals are: !ITA's past accomplishments in resistance - to develop systems for the management breeding permit an important change of em· and conservation of natura] resources for 8 sustainable agriculture in humid and humid and s.ubhumid tropics of Africa. sub humid tropical zones. There is global lIT A has 20 years of experience dealing with concern that Africa's rapidly growing these ecologies, where falling per capita food population is placing increasing pressure on prod uction makes them areas of great con­ the basic natural resources and threatening cern. These ecologies, roughly congruent the viability of traditional farming systems. with West and Central Africa, contain half - to increase the productivity of selected the population of sub-Saharan Africa. This food crops and to integrate them into im­ strategy does not conflict with the interna­ proved production systems. This is the cen­ tional character of IITA, for we will con­ tral thrust of the CGIAR system, the ap­ tinue to promote those commodities for proach that initiated the Green Revolution in which we have a broader responsibility in all rice and wheat, and it remains valid for of sub-Saharan Africa and beyond. tropical Africa although the problems are c) Greater farming systems orientation more complex and the rate of achievement throughout lIT A to assure that technology not as spectacular. generated is within the management - to strengthen national agricultural capability of the family farmer. The con­ research capacities in developing countries in tribution of research to greater food produc­ order to accelerate the generation and tion during the coming decade will come utilization of improved technologies by largely from improved varieties developed means of training, information and other by commodity research programs. But there outreach activities. The objective is to enable will be little impact unless these varieties are our partners in national systems increasingly productive in the complex environment of to meet their own technology requirements. the African farmer. After considering - to imprm'e postharvest technologies and various organizational alternatives for pro­ realize the more complete utilization of food moting the necessary multidisciplinary col­ crops within IITA's mandate. For a number laboration, IlTA adopted the simple innova­ of lITA commodities, particularly roots and tion of interprogram, commodity-based tubers, the lack of efficient technology for working groups. These working groups are storage, processing, and conversion to com­ providing a mechanism to increase the short­ mercial products is a serious barrier to their run productivity of the commodity programs increased use for both food and feed. by sharpening their focus on problems faced 2. Operating strategies - To provide at the farm level, as well as bringing the coherence and effectiveness in pursuit of its benefits of the longer-term resource manage­ goals, lITA will follow five key operating ment research to the farming system. strategies: d) Decentralization to satellites. In addi­ a) Emphasis on the family farmer. As a tion to the working groups, a second means matter of policy, lIT A's research objective is to promote understanding of farmers' needs to increase the productivity and income of will be the establishment of three or four the African family farmer. Our ultimate research substations, as satellites, in key targets are African smallholders who are ecologies. These satellites will be staffed by committed to improved management prac­ small teams of scientists, who, because of tices and who have sufficient reSQurces to their location, will be able to set research ob­ produce a surplus for the market. These are jectives and strategies based upon close the farmers who, by increasing commer­ study of the farming systems in their cialization of their operations, can adopt the ecology. Strongly supported from lbadan improved technologies that will be the driv­ headquarters, they will increase the In­ ing force for agricultural change. stitute's ability to help national programs (b) Special focus on improving the pro­ develop new technology. ductivity of farming systems in the lowland e) Strengthening national agricultural 9 research systems by devising new of the need for upstream research), on soy· mechanisms for cooperation and training. beans (because of their future potential), and liT A is acutely aware that the technology it on plantains (because of their importance in generates is of little value in the absence of the farming systems of the humid tropics effective partnership with national systems, and the presence of critical researchable which can extend the technology to farmers. problems). There will be a gradual and There are plausible explanations for the deliberate increase in emphasis on reSOurce modest impact of agricultural research in management research, especially in the Africa, including the harshness of many humid forest zone, because this is one of the ecologies, the variability in the environment, major, long-term problems of African poorly developed infrastructure, and agriculture, a challenge that is at the heart of government policies that have been biased !ITA's mission. against agricultural development. But !ITA Finally, I believe we are developing a new cannot accept these explanations as a basis sense of scientific purpose at IITA, a basic for complacency. philosophy and vision of the future that can Although !ITA has not developed a for­ guide and enhance the policies and actions of mal model for working with national the present. We are also engaged in agricultural systems - and it is not certain organizational changes to improve !ITA's that a single model is desirable - the In­ capability to realize its goals with maximum stitute is engaged in a multiplicity of dif­ economy and effectiveness. Our organiza­ ferent approaches: research networking, in· tional objective is an !IT A with a high degree ternational testing, regional coordination, of scientific creativity; with organizational institution·building associations with na· cohesiveness based on a common philosophy tional systems, and other outreach activities. and shared values; with a decentralized, lean Like the other international centers, I1TA operating structure; with an ecological and has a unique comparative advantage in train­ systems orientation to assure understanding ing because of its intimate linkage with ap­ of our ultimate consumers; with effective plied agricultural research. In a recent study working relations with national agricultural of CGIAR training, Professor Hugh Bun­ research organizations; and with resources ting generalizes that "through its special ad­ clearly focused on the most critical prob­ vantages of continuity and cooperation, the lems. international agricultural research system is building up living linkages in a world-wide Organizational Changes invisible college, based on continuing per· There were significant changes during the sonal relationships, which has no parallel past year in the management and Board of anywhere else". The best course for dealing Trustees of IITA. In recognition of the com­ with the local specificity of national settings plex management problems of IlTA, the is not yet charted, but lIT A is systematically Board created the new position of Deputy and continually exploring alternative Director General for Management, and Mr. models, especially in cooperation with the John H. Davies was appointed to this posi· other CGIAR centers. tion in November. International Coopera­ 3. Program Priorities - As a result of the tion and Training was reorganized into two Strategic Planning Study, liT A has made separate programs. To underscore the priori­ fundamental choices concerning research ty we must continue to accord to training, priorities within and between programs. The the position of head of training was upgrad· primary commodities in lITA 's future ed to the status of a director, and Dr. Heinz research program will be cassava, rice, maize Gasser was appointed to this new position. and cowpeas. Core resources will continue to After 17 years of invaluable service on the be allocated for research on yams (because Board, Chairman John J. McKelvey, Jr. 10 passed the mantle of leadership to Lawrence with highly relevant experience in a sister R. Wilson. As a respected scientist and CGIAR center; Luis Crouch, successful educator, Prof. Wilson brings experience businessman and authority on the manage­ and wisdom to the leadership of the Board. ment of agricultural research; Freeman L. All three of the Nigerian ex-officio Trustees t\.1cKewan, distinguised educator and scien­ changed during the year. Alhaji A.G. Gobir tist; and Kunia T oriyama, former Director replaced Mr. John D. Edozien, Dr. Sheriff General of Japan's National Institute of Adetunji replaced Mr. Dominic E. lyamabo, Agrobiological Resources. These changes and Prof. Chimere Ikoku replaced assure that UTA will continue to have a Prof. Ango Abdullahi. The Board lost the Board with members who are responsible. services of three Trustees who completed informed, and actively engaged. their second terms: Dr. Hidetsugu Ishikura, Dr. Edmond de Langhe, and Mr. Mowbray S.O. Nicholas; these Trustees embodied enormous experience in international agriculture and tropical Africa. Four new Trustees bring special strengths to the Board Laurence D. Stifel Randolph Barker, professor of agricultural economics at Cornell University May 1987 11 LAKE CHAD Q REPUBLIQUE DUCAMEROUN CONSO Zone Principal food crop(s) Western Highland Maize II Coastal Lowland Root and tuber crops III South Cameroon Continental Land Root and tuber crops IV Adamaoua Root and tuber crops and maize V North Cameroon Sorghum and millet Figure 2. The five major agro-ecological zones in lhe Republic of Cameroon (lolal populalion = 9 million) 12 Developing Strong National Research Capabilities in Africa: Real Progress in Cameroon A central aim of the CGIAR in Africa is to institution building and manpower develop­ assist in the development of st rong and effec­ ment through the provision of guidance, tIve indigenous research capacities within assistance, scientific personnel and training. countries. While international crop research While such an approach has been the cen­ centers are recognized for their achievements tral strength of CGIAR efforts to date, it has in developing improved varieties and not always led to the establishment of endur­ more efficient farming systems for major ing agricultural research capabilities at na­ food crops in given regions, their ultimate tionallevels. This has been due to many fac­ goal is to assist in building and developing tors such as the onmmitment of national gov­ institutions and national capabilities that can ernments to effective agricultural develop­ meet domestic research needs. ment policies. In such circumstances, inter­ The task of national institution building in national centers often cannot provide effec­ Africa today is complex and tough. In most tive and intensive follow-up training within instances, basic capabilities have to be countries. Without national policies that are developed from scratch with limited consistently supportive of agricultural resources. There are critical deficiencies in development, it is difficult to make enduring areas such as research planning, manage­ contributions. ment and evaluation within countries. Effec­ In 1980, the Government of the Republic tive guidance is crucial in the early stages of of Cameroon in its fifth five-year plan national program development as are well­ (1981-1985) made self-sufficiency in food conceived and adequately funded projects. production the major aim of agricultural International centers have traditionally development policy. Specific priorities were assisted national programs through special identified for rural development, including projects that afford opportunities for improved productivity from the predomi- A good harvest of sweet potatoes from demonstration trials in a farmer's rleld near Ngaoundere . Adamaoua. Central Cameroon . The liTA variely, Tlb I, has consis tently given high yields since it was introduced to Ihis region. 13 Focus nant small-scale farmers of Cameroon through greater investment in research, training and the provision of information for farmers. The Government of Cameroon recognized clearly that increased food pro­ duction was needed to support a steady growth in population and the migration to urban areas that started in the late seventies. There was the determination , not only to increase farm output from small farms across diverse ecologies, but to develop clear-cut ideas as to how this could be best achieved. First, there was an urgent need to strengthen national institutional capacity for agricultural research on major crops in­ cluding maize, rice, sorghum, millet and tuber crops, with specific emphasis on train­ ing scientific personnel. Second, improved farming systems and component production technologies flowing from such research would be tested and adapted in close coopera­ tion with farmers in local ecologies; produc­ tion packages to increase productivity would have to be demonstrated and proven under actual farm cond.itions. In 1981, the Government of the Republic A nalional "counlerpart " scientist assesses maize cobs rrom improved hyb rid varieties thai are being developed of Cameroon, in conjunction with the and tested in the highlands of Cameroon. A project 10 United States Agency for International dc"elop suitable hybrid nrieties ror highland and Development (USAID), agreed to fund lowland ecologies is now underway. jointly a major project of research, training and extension to increase cereal production. UTA was contracted to provide technical This interaction and cooperation between assistance for the project. The National international and national scientists was not Cereals Research and Extension (NCRE) just central to the local research and extension project was designed to be a totally in­ effort to increase food production- it was tegrated effort between international and the basis for the intensive training of national local personnel. International scientists with scientists . The concept of "counterpart train­ the NCRE project work as part of the 'ing" is a central feature of the NCRE pro­ developing national research system - the ject. One international scientist works very Institute of Agronomic Research (IRA). closely with one or two local counterparts This Institute has research stations located (plant breeder or agronomist) under local throughout the cou ntry to faci litate research conditions. Intensive on-the-job training is across the diverse climates and soils of combined with specialized courses. The great Cameroon. This network proved vital to the strength of this approach is that the specific relevance and impact of the NCRE project. training needs of national cou nterparts are NCRE scientists were generally brought into identified by experienced scientists with due contact with local farmi ng conditions and a regard to individual capabilities and local realistic basis existed for close collaboration research priorities. The personnel categories between NCRE and scientists from IRA. and numbers trained to date through the 14 Focus Number trained state development agencies set up to direct 120 and manage local food production projects. Testing and Liaison Units (TLU) have been established as part of the NCRE project to bridge the gap between researchers and 100 --~+ ----___- -! farmers. Each TLU, which includes an agronomist and an agricultural economist or socia-economist, transmits production technologies to farmers and provides feed­ 80 ,• ,~ back to researchers on the real farming con­ ditions and problems. Four TLU's are now in operation in Cameroon. 60 ~ 1 While the Government of Cameroon took a major and successful initiative 10 expand cereal production through the NCRE pro­ 40 ! ject, the commitment to research in root and tuber crops has not only been maintained but has been strengthened. From a staff of one root crop scientist in 1970, the Cameroon­ 20 ian National Root Crops Improvement Program (CNRCIP) has developed to a pro­ gram with 12 scientists, most of whom have been trained to M.Sc. and some to the level o of Ph .D. Technician Research Extension Scientist Like the NCRE, the CNRCIP is a col­ laborative venture involving the Institute of Figure 3. Training of National Cereals Research and Ex­ Agronomic Research (IRA), llTA, the Inter­ tension personnel in the first phase of the NCRE projecl national Development Research Centre (1982-86), Republic of Cameroon. Thirteen of the research scientists have obtained, or are in the process (IDRC), Canada and the Belgian General of studying for, postgraduate degrees from universities Agency for Development (AGCD). Improved in the U.S.A. varieties of foot crops were introduced and adapted to local farming conditions. NCRE project are shown in Figure 3. On­ Under the leadership of Dr. Simon Lyonga, the-job training has been combined with in­ the CN RCIP got farmers actively involved in service training (short courses at inter­ demonstrating the benefits of the new pro­ national research centers) and degree-related duction technologies. Research activities training. Under the auspices of the NCRE were moved closer to the actual farm situa­ project, 13 Cameroonian scientists have tion through demonstration trials in received postgraduate training in areas such farmers' fields; some of the trials were as rice, maize and sorghum breeding, managed by farmers . In this way, researchers agricultural economics, plant pathology, developed a deeper understanding of and extension agronomy. It is the training at how improved technologies perform on these high levels, supplemented by adequate farmers ' fields and how they might best be numbers of technically trained support per­ adapted to local, traditional cropping sonnel that creates the basis for meeting systems. The staff of CNRCIP are convinced long-term national research needs. that this approach works. It removes bar­ The NCRE project also trains personnel riers between farmers and scientists and from extension services and oarastatals - opens up effective communication between 15 Focus The UTA research learn in the Republic of Cameroon - a multidisciplinary group of plant breeders. agronomists and social scientists who have been involved in one of the most intensive projects yet to develop the research capabilities of nalional programs in Africa. them. Commenting on this partnership be­ traduction and utilization. Detailed infor­ tween farmers and scientists. Simon Lyonga mation on the impact of liT A research stated: efforts in cereals, root crops and farming systems in Cameroon has been reported in previous /ITA Annual Reports and Research "It opens the local door to new Highlights, 1983, 1984, 1985. The major technologies and cropping systems and it achievements of these projects in Cameroon allows researchers to tap the farmers since the late seventies include: wisdom. We can find out why farmers sometimes, quietly but effectively, say • Self-sufficiency in most food crops and 'no' to new technologies. More impor­ 80010 self-sufficiency in rice production tant, however. we can together work on (see Figure 4). what adaptation or change is required to gain acceptance for new technology. This • A strong institutional capability has been usually involves change for both research­ developed for national research through er and farmer." intensive training of scientists and techni­ cians. This capability has been developed The CNRCIP has also benefited from for all regions of the country. direct national involvement of international • Linkages between researchers, extension scientists. Two IITA scientists work with agents and farmers have been strength­ the CN RCIP team and concentrate on the ened. important root crop areas of Cameroon such • The technical support and backstopping as the Central and Southwest provinces. The provided by international centers have central region of Adamaoua has, in recent been effectively harnessed for national years, been a good area for root crop in- program development. 16 Focus Production ( X 1000 tons 1 200 ,.---------------------------, 160 120 80 This rice vuriety was developed and adapted fo r irrigutcd production in thc Mbo plains of Southwestern 40 Cameroon where yields of 5-6 lons/ ha were obhtincd in farmers' triads. O ~I --~~----L-----~----~----~ 1971 74 78 82 86 90 • The technical assistance and backstopping Yeor available from UTA to provide scientific figure 4. Rice production trend in Cameroon manpower and expertise in the develop­ ment of national research capacities. Also These achievements can be attributed to the experience and capability of IlTA in many fa ctors but when the first phase of the training was crucial to the NCRE project. NCRE project was evaluated it was generally • The teamwork and quality of collabora­ agreed that the following were central to the tion among development agencies, na­ success of the project to date : tional policymakers and scientists. The NCRE project has now entered its • The commitment of the government of second phase and there is optimism tha t a Cameroon to agricultural development. sound basis exists for further progress which • The willingness of donors such as USAID may make the Republic of Cameroon, if not to provide positi ve and generous support a model, then certainly a good example of when national commitment to agriculture what is possible in African agriculture in the is real and serious. eighties. 17 Deus Research Achievement on Maize Streak Virus Wins King Baudomn Award lITA won the 1986 King Baudouin Award the annual consumption of maize per capira for International Agricultural Research in exceeds the 21-kg world average. In several recognition of multidisciplinary research countries in East and Southern Africa, con­ that led to a breakthrough in solving the prob­ sumption exceeds 100 kg per year. This lem of maize streak virus (MSY) in Africa. makes the signi ficance of maize as a cereal At a meeting of the Technical Advisory crop on the African continent comparable to Committee (TAC) of the CGIAR held in that of wheat in the Middle East and rice in June 1986 at CIAT, Cali, Colombia, lITA southeast Asia. But throughout Africa maize was selected from among all the interna­ yields are low , averaging only I t/ ha in most tional centers for this biennial award wl:tich countries. Although nearly 11 '70 of the world was firs t established in 1980 and is funded by area devoted to maize is in tropical Africa , the Government of Belgium . The purpose of maize production in the region is only 3'70 of the award is to give international recognition world production. The steady increase in to major achievements by centers. production in the region (about 2'70 a year Maize is the major cereal crop in Africa, a from 1961 to 1980) is almost completely due basic staple food in Kenya, Malawi , Zambia to expansion in the area culti vated . and Zimbabwe, and an important compo­ While yields and overall production levels nent o f the diet in many other African coun­ are limited by many factors such as climate, tries. In most countries of tropical Africa, poor soils and restricted inpuls, di seases have Streak resistant maize alongside a susceptible variety in field trials at IITA. 18 Focus always been recognized as a major cause of that plants infected less than a week after low yields. Maize streak virus (MSV) is one germination produced no yield; those in­ of the most economically damaging diseases fected at three weeks produced about 50% in sub-Saharan Africa. It is found only in yield; and those infected at eight weeks pro­ Africa and surrounding islands where it is duced the normal yield. Crop failures result widely distributed. The disease is spread by where virtually all plants in a field are in­ leafhoppers of the genus Cicadulina and oc­ fected within eight weeks of germination. curs sporadically because the populations of Chemical control of the MSV vector with this insect fluctuate. Many graminaceous insecticides can mitigate the disease but is crops and weeds are also hosts. neither cost-effective nor reliable under The effects of MSV on maize crops vary African farming conditions. Chemicals are enormously, from negligible damage in some frequently unavailable or expensive, and years to total devastation when epidemics many farmers do not have access to basic occur. Outbreaks of MSV are often spraying equipment. Once a plant is infected associated with drought or irregular early with MSV, no further control of the disease rains, and the symptoms associated with the is possible, so subsequent spraying of the disease have long been recognized by vector is of no use. agriculturists and farmers in Africa. To ob­ In 1975, scientists at UTA, Ibadan, tain reliable estimates of yield loss due to Nigeria, initiated research that aimed to MSV infection, UTA conducted six ex­ develop a solution to the problem of MSV in periments between 1978 and 1982 using con­ Africa. Be cause of the complex trolled methods of infestation with resistant epidemiology of the disease, a team ap­ and susceptible varieties. On average, streak proach was adopted, with virologists, en­ infection reduced yields by 70"70. tomologists, pathologists and breeders Apart from direct effects of ,evere yield working in close cooperation with scientists losses,there are also indirect effects on maize from national research programs in Africa. production. The risk which accompanies the The research team had three major objec­ unpredictable effects of the disease is con­ tives: sidered by agriculturists in Africa to be a ma­ jor factor contributing to the traditional lack • To develop a suitable and reliable method of confidence among farmers in the maize of screening for MSV resistance. crop. African farmers, like farmers • To identify sources of resistance and everywhere, will not commit resources such develop parental materials with stable as improved management, good husbandry multigenic resistance. and costly inputs to an unreliable crop. In • To develop streak-resistant maize the case of maize, they know that it faces a varieties. high probability of failure if it is infected by MSV. The erratic occurrence of the disease under Plants infected with MSV show charac­ natural field conditions led to inefficient teristic chlorotic lines along the leaf veins screening because plants that" escaped" in­ and this pattern of infection is usually fection by the virus could unwittingly be distributed uniformly over the leaf surface. selected as exhibiting resistance. Therefore, After infection , these symptoms develop only the development of appropriate and uniform on new growth and existing leaves remain screening methodologies was 8 prerequisite unaffected. This means that the growth stage for breeding resistant varieties; scientists of the plant at the time of infection can be concentrated their efforts on developing an estimated. The critical growth stage for in­ effective screening technique initially in a fection with MSV is during the eight-week screenhouse and later under field conditions. period after germination. Studies on the ef­ Eventually a technique was developed that fect of the age of the plant at infection show enabled scientists to rear 200,000 leafhop- 19 Focus Clcadullna rriangula, the leafhopper veclor (hat Anesthetized leafhoppers are shaken from a vial onlo Ir1lnsmHs maize streak virus disease. h.'II\'cs of maize seedlings for streak resistance screenin~. pers and infest 50,000 plants each week in major task for scientists. Two sources of the field. resistance, IB32 obtained from the liTA The screening technique developed involved population TZ-Y and "La Revolution" in­ a number of important scientific innova­ troduced from Reunion Island, were iden­ tions: the best vector leafhoppers were iden­ tified initially . Scientists were also concerned tified and those fami lies that had the highest to avert the possibility of future breakdown frequency of transmitters were selected; of the resistance developed. A wide range of maize plants were replaced with millet plants virus strains, not only from maize, but from which increased the number of eggs laid per wild grasses and diverse Iocations, was used unit area; the period during which leafhop­ in infestation to develop resistance to all pers acquire the virus in cages was doubled known potential sources of virus infection . from 24 to 48 hours thereby doubling the Many varieties crossed with the initial number of active transmitters; the use of car­ resistance sources were tested using the in­ bon dioxide to anesthetize virus-carrying novative screening techniques described leafhoppers ensured that the insects stayed earlier. The stability of the resistance was long enough on each plant in the field to in­ then tested and confirmed in many parts of fect it. Thus, "escape" from infection was West, Central, East and Southern Africa . minimized. The final step was to develop a large The identification of original sources of number of maize varieties that combined resistance and the development of a stable resistance to MSV, desirable agronomic multigenic resistance source was the second characteristics and suitability for the diverse 20 Focus African children in Irno State. Nigeria celebrate a good maize hanes!. The recent breakthrough on maize streak virus disease combined with the development of improved. high-yielding varieties has crealed real opportunity to increase maize production in Africs. consumer requirements and maize-growing vaneties, mostly developed by CIMMYT, ecologies of Africa. IITA and the Interna­ are presently being converted. tional Maize and Wheat Improvement The streak-resistant materials have been Center (CIMMYT) have cooperated to made available to 36 national research pro­ develop more than 100 open-pollinated and grams in Africa for further multiplication hybrid maize varieties. These varieties cover and distribution to farmers. Streak-resistant almost all the major maize-growing materials have already been multiplied and ecologies in Africa including lowland , humid grown in many countries, including the and subhumid tropical rainforests, savanna Republic of Benin, Ghana, Nigeria, Sao­ regions and mid-altitude ecologies Tome and Principe, Tanzania, Togo and (800-1500 m). Zambia . But the considerable potential of The varieties developed also meet the the streak-resistant, high-yielding varieties wide-ranging local preferences of African developed by llTA has yet to be fully ex­ farmers and consumers with regard to ploited across the African continent. maturity range (early, intermediate or full ­ In Nigeria, however, the benefits of the season maturity), grain color I and grain tex­ newly developed varieties have been ture. White- and yellow-colored maize demonstrated to farmers and the response, varieties have been developed and, for each in terms of acceptance and the extent of color, two grain types, flint and dent, are adoption, underscores the significance and also available . Part of the streak resistance relevance of the breakthrough on MSV. In breeding program was devoted to the con­ 1985, five open-pollinated varieties and eight version of otherwise superior non-streak­ hybrids resistant to MSV were officially resistant varieties by backcrossing. And 15 released in Nigeria . By 1986, 250,000 hec- 21 Focus tares were seeded to streak-resistant varieties undertaken by the FAO, indicates that 424 and the Nigerian National Seed Service ex­ mjllion hectares of land in Africa are pects that two million hectares will be seeded suitable for maize growing . As it is estimated to these improved varieties by 1990. that 19 million hectares of maize are grown What has been accomplished in Nigeria annually in Africa,there is plenty of scope to can be achieved in many other African coun­ expand the cropping area allocated to maize tries and the "seeds" of future success have production and there are promising indica­ already been made available to national tions that countries in West and Central agricultural institutions in 36 countries. Africa are intent on giving maize research The potential for increased maize produc­ and production a high priority in their na­ tion in Africa is considerable. A recent tional agricultural development plans . survey of agroecological zones in Africa, 22 J Annual Report Executive Summary Resource and Crop Management Program The Farming Systems Program at lIT A has been renamed the Resource and Crop Management Program. This change recognizes that although there is a close link between farming systems and resource-management research, there is also an important distinction. Farming systems research is aimed at increasing crop productivity, which often can be accomplished in the short term; resource-management research, aimed at improving management of resources, is general­ ly concerned with longer time periods. The goal of IITA's resource-management research is to develop economically viable farming systems for increased and sustainable production by progressive family farmers, while conserv­ ing the natural resource b~se. The resources include soil, vegetation, water, labor and other energy sources and material inputs. Sustainability involves maintaining the productive capabili­ ty of these resources over time. The target area of UTA's resource-management research is the lowland humid and subhumid tropics of West and Central Africa. This research is to be carried out by teams of scientists based at headquarters and at satellite stations. The crop-management aspect of the program's research will be handled by working groups established for cassava-, rice- and maize-based cropping systems. An objective of the three crop-management groups is to develop improved cropping systems that integrate component technologies developed by IITA's four commodity programs with innovations from the resource-management research group. The working groups will therefore help to strengthen the collaboration between !ITA's research programs in addition to strengthening the linkages be­ tween lIT A, other international institutions and national research systems. Another objective of the working groups is to provide a framework for understanding the progressive family farmer in major ecological zones in which particular cropping systems predominate. These working groups will be a valuable source of information for the more basic resource­ management research group. The small farm will be the central consideration in the activities of both the working groups and the resource-management research team. During 1986 research was conducted in the program by scientists working in four research teams (upland production systems, wetland production systems, agroforestry and plantain research, and on-farm research) and one unit, the Socioeconomics Unit. Upland Production Systems As in previous years the upland research team focused on soil- and crop-management systems based on cassava, yams, maize, cowpeas and soybeans. Studies were conducted in soil physics, soi1 chemistry, soil microbiology, agricultural engineering, weed science and agronomy. In a joint project between UTA and the United Nations University, the effects of deforesta­ tion and land use were studied at Okomu, near Benin City, Nigeria. Soil degradation was least for the forested control and for traditionally farmed plots. Mechanically cleared plots sown to cassava-maize-cowpea in rotation showed the greatest soil degradation. 23 Soil erosion is a major problem in the high-rainfall tropics, and 1986 studies showed that soil erosion can be substantially reduced by alley cropping. However, there may be some yield reduction in alley cropping because of competition between the crops and hedgerows. Results from a series of experiments in 1986 to study the effect of tied ridges on crop water use, root growth and crop yield in the Sudan savanna of Burkina Faso showed that yield of cowpea was not affected by tied-ridging but that the total dry-matter production of inter­ cropped maize and Stylosanthes was increased by tied-ridging. Stover and grain yield of millet were also greatest on tied-ridge plots, but tied-ridging decreased land equivalent ratios (LER) below 1.0 whereas flat planting increased LER's above 1.0 for intercropped millet and Barnbarra groundnuts. Other trials identified Lablab purpureus cv. as a potential cover crop in the Sudan savanna and Cajanus cajan, Prosopis julifera and Jatropa curcus as promising shrubs for alley cropping. Soil acidity greatly limits crop yields in the highly weathered and strongly acidic L'ltisols and Oxisols that comprise more than 60"1, of the total area in the humid tropical regions. In soil acidity and liming trials, 85"70 of the maximum yield of maize was obtained at a pH level of 4.8, exchangeable-aluminum saturation of 38"70 and exchangeable-calcium saturation of 45"7,. In another study of the acidification of Alfisols, which are important in the sub humid zones of Africa, it has been shown that with nitrogen fertilization using ammonium sulfate, there were significant reductions in yield and N uptake in maize-maize monoculture and maize-cowpea rotations over a four-year period; there was no significant effect on yield and N uptake in plots receiving nitrogen in the form of urea and calcium ammonium nitrate. It is believed that the yield decline using ammonium sulfate may be due to the large increase in the available­ manganese content of the soi1. Alley cropping research conducted during the year showed that prunings from three hedgerow species (Cassia siamea, Fiemingia congesta and Gliricidia sepium) were of most benefit to the associated maize crop when they were applied either two weeks before or at planting. In addition to providing a source of mulch to the food crop, trees and shrubs used in alley cropping can also control weeds through the shade they provide. Studies conducted during 1986, however, indicated that weed control is not the primary benefit to be derived from alley cropping. Maize-cassava intercropping is commonly practiced by African farmers. Such intercropping systems are being studied in order to determine how maize population affects cassava yields. In 1986 trials, tuber yields were generally unaffected by maize populations of 10,000 - 80,000 plants/ha. However, the average tuber size decreased as maize population levels increased. Wetland Production Systems Research on wetland production systems in 1986 was limited to a few hydrological and agronomic trials in hydromorphic and inland valley swamps in Nigeria and Sierra Leone. Results from Sierra Leone indicated that with the use of simple water-control measures and im­ proved varieties and cultural practices, crop-yield increases of up to 30"70 could be obtained without the use of imported inputs such as fertilizers. Preliminary trials at IITA have shown that it is possible to get reasonable yields of a wide range of field and vegetable crops after rice in hydromorphic soil. Only watermelon and snap bean (pole type) had unsatisfactory yields under improved management. 24 At present, less than 207. of the 200 million hectares of wetlands in tropical sub-Saharan Africa are cultivated, yet the development of the wetlands for cultivation could lead to greatly increased food production in the region. Computation of water balance for the Sudan savanna of Nigeria showed that in a valley where a head dike and peripheral irrigation canals had been installed, 1507. of the valley bottom areas and 75% of the fringe areas would not have enough water for production of early-maturing rice varieties, while in a second valley without the head dikes and irrigation canals, 3507. of the valley bottoms and about 9007. of the fringe areas would not have sufficient water for a short-duration rice crop. Agroforestry and Plantain Research Agroforestry research conducted at IITA during 1986 included the continuation of alley crop­ ping trials, the investigation of the problems of establishment of woody species and the study of compound farms in eastern Nigeria. Some preliminary on-farm alley cropping research was conducted as well. Woody species that establish quickly are necessary in alley cropping systems. Depth of seeding can affect both the rate and the extent of germination. Pot experiments with Cassia siamea, Gliricidia sepium and Leucaena /eucocepha/a showed that Leucaena had good emergence at planting depths ranging from 0.5 to 6 cm while Cassia and Gliricidia were adverse­ ly affected if planted at depths greater than 2 cm. In alley cropping with Leucaena and maize, earlier findings that Leucaena prunings could replace fertilizer applications of up to 40 kg Nlha were confirmed in 1986. Tillage was also found to increase nitrogen availability from prunings and other residues in a11ey-cropped plots. In addition to Leucaena and Gliricidi£l, other species are being studied for their suitability for use in alley cropping. Through trials established at Ibadan and Onne, species that grow well under the ecological conditions of these locations and that can be used for multiple purposes (e.g., as fuelwood, as fodder for livestock and as staking material for yams) are being investigated. A major part of the plantain research is conducted by national research institutions through the West African Regional Cooperative for Research on Plantain (WARCORP). In an experi­ ment to determine the effects of retaining fallow residue and regrowth after a 13-year bush fallow versus nometention (Le., burning of the fallow vegetation), higher plantain yields were obtained in the burned treatments, with as well as without fertilizer. The experiment will be continued in order to determine if this advantage is maintained in subsequent years. Also, because high levels of organic matter are associated with plantain productivity. different methods of obtaining mulch are being evaluated for their effects on plantain growth and yield. Efforts to identify plantain and cooking banana germ plasm that is resistant to black sigatoka, a disease recently detected in West Africa, continued during 1986. On-farm Research Technologies that have been developed and tested on station are later tested under farmers' conditions in on-farm trials. In 1986, on-farm trials were conducted in Bida, Ayepe and Alabata/ljaiye in Nigeria. On-farm trials were also conducted in Burkina Faso, Republic of Benin, Rwanda, Cameroon and Zaire. A number of ecologies are represented by these loca­ tions. 25 In farmer-managed on-farm trials in the Ayepe area, UTA improved maize variety TZSR-W out yielded the local variety by about 30'1'. with and without fertilizer. Factors accounting for the variability in yield between farms included shadiness of the fields, number of years of previous cropping, planting date, amount of weeding and stand establishment at harvest. In on-farm trials conducted during the year in the Republic of Benin, there were no dif­ ferences in yields of the local cowpea variety and yields of the improved lITA cowpea varieties. Participating farmers, however, were very interested in lIT A variety IT 82D-1137 because of its cooking quality, earliness and white seed color. This variety fetched a 20 - 25'1'. price premium in the local market. In the western highlands of Cameroon, fertilizer trials on farmers' fields showed that there are economic benefits to applying moderate rates of nitrogen (75 kg/hal but that there was no yield response to phosphorus in maize-bean intercropping systems. Other trials indicate that without fertilizer, there is no advantage in farmers increasing their maize plant densities above their present average of about 30,000 plants/ha when growing maize in association with groundnuts. In Rwanda, leguminous shrubs were tested in alley cropping trials first established in the semiarid region of the country in 1983. Cassia spectabilis gave the best results in terms of biomass production and yields of beans and maize planted in the 1985 season and sorghum planted in 1986. In trials of cassava varieties on farmers' fields in Rwanda, there was a steady increase in yield of bitter cassava varieties with advance in age of harvest from 10 to 18 months. There was not much increase in yield for sweet varieties. Also, the quality of sweet cassava varieties deteriorated after 12 months due to fungus attack or to increases in fiber content of the tubers. Socioeconomics Unit During 1986, members of the Socioeconomics Unit prepared a number of background papers on agroecological zones in West and Central Africa, on population trends and their implica­ tions, on changes in the agricultural economy of the region and on the economic importance and role of each of the main crops for which liTA has a research interest. Market-price surveys of UTA's mandated food crops continued for a second year in the Ijaiye/ Alabata area, and new emphasis was given to postharvest technologies as part of the on-farm research model and also to women's roles in agricultural production and utilization. Soybeans received increasing attention, and a farming systems package including both production and utilization was designed. The potential for improving upland rice production in southwestern Nigeria was also studied during the year. Results indicate that the adoption of improved rice technology by farmers would likely lead to increased returns to labor and profitability of the rice enterprise. The rice enterprise, however, may still not be as profitable as enterprises involving crops such as maize and yam, which are also cultivated by the farmers. Additional information on research activities referred to in this summary is available in the Annual Report of the Resource and Crop Management Program. 26 Nitrogen Contribution of Hedgerow Trees in Alley Cropping Systems Prunings of hedgerow trees used in alley (single superphosphate at 60 kg P/ ha) and cropping provide a source of nitrogen (N) to potassium (muriate of potash at 30 kg Klha) the associated food crop when they are ap­ were broadcast on the plots before planting, plied as mulch or green manure. In 1986, the The N content of maize when Gliricidia N contributions of three species (Flemingia prunings were applied was higher than that congesta, Cassia siamea and Gliricidia when prunings of the other two species were sepium) to a maize crop were determined. applied (Table I), which is a result of the Plots were established on a degraded Alfisol greater amount of nitrogen released from the at !ITA in Ibadan, Among the quantities decomposing Gliricidia prunings than from measured were N content of the maize plants the decomposing prunings of the other at eight weeks after planting and grain yield . species. The maize N contents for Flemingia Prunings of Fiemingia (3 t/ ha), Cassia (8 and Cassia were simi lar to each other. t/ ha) and Gliricidia (5 t/ ha) were applied to Prunings applied during the period three plots from three weeks before planting maize weeks before planting up to planting had an to four weeks after planting. Phosphorus effect on N content of maize that was ,.: ~ ... -, . . - \, ",'''-:,::~-~,'' II~~', -n"'......"1 .,':iJII'" r · ~- " "·1"·- '.... ...' )"._,. - --~~\. , .",,''( ~. .) ,,"' ...r rJ 1' ... '_",,, . ~ '.' " ...... ~ ~- ~ - ., . '. . ,1 , ~', " l• '\ .. -'-- - ")L". . . ,~.-, .it_', ~/ . . I _ __, .'~ ,l 1.4 4b 0.6 63.6a 4.3 Cndefoliated 38 a 2.2 10 a 0.9 81.7a 10.00 IT 82D-716 Defoliated 63 d 5.0 26d 0.7 241 c 23_6 Undefoliated 93 c 4.7 36c 1.9 380b 43.8 1 Analysis is based on values transformed to arcs in Ix/lOO 2Analysis is based on values transformed to ~ 1,2No, of larvae/30 flowers vs 070 flower infestation, r = 0.93"'*(n = 16) in the undefoliated treatments (Table II). While it is not likely that one cultivar Therefore, higher temperatures and lower would have all these structural features, RH are features of open canopies which many cultivars can be developed quite easily result in lower infestation and reduced with wide pod angle and exposed peduncles. damage by the MPB. This is, however, The addition of these two features alone achieved at the cost of reduced parasitization would make a difference in relation to MPB from beneficia Is which appear to prefer a damage, and should be encouraged while the more humid and cooler environment. search for the classical mechanisms of The results obtained in all three ex­ resistance continues. periments provide a range of options to host plant resistance breeding from the MPB. A number of these plant architectural features may already be present in breeding lines but have not been given specific attention up to now. The findings here indicate that plant architecture is important in relation to pod borer damage. 48 Breeding for Multiple Disease and Insect Resistance in Cowpea Diseases and insect pests are the major con­ Table 12. It has brown rough medium-sized straints to cowpea production. Therefore, seeds that are preferred in West Africa. II concert ed efforts a,e being made at IlTA to contains about 300/. protein and takes a develop cowpea varieties combining all the relatively short time to cook (35-40 minutes). available sources of resistance 10 major IT 845-2246-4 is a progeny of a single F6 diseases and insect pests and also having plant selected from the cross between high yield potential, desirable seed types, IT 810-1020 and IT 820-716 which was varying maturity and various plant types. made in 1982. IT 820-1020 combines Through systematic cycles of hybridization resistance to several diseases with resistance and selection, a number of breeding lines to aphid and bruchid whereas IT 820-716 is have been developed that combine several resistant to thrips and bruchid as well as sources of res is tan ce with desira ble several diseases. The development of this agronomic and seed characters. One such variety is the result of long and systematic ef­ line is IT 845-2246-4. It matures in 65 days forts involving sustained teamwork among and combi nes moderate to high level of breeders, entomologists and pathologists. resistance to 10 diseases and three insects IT 845··2246-4 was distributed for -aphid, bruchids and thrips, as listed in mullilocationaltrials in 1986. Available data The cowpea variety, IT 84S-2246-4 , showing erect and uprighl podding. 49 provided to date (Figure II) by UTA and Nigerian scientists indicate that it has good yield potential. Table 12. Reaction of IT 845-2246-4 10 different diseases and insect pests. Reaction score Major diseases Major insects Res istant Cowpea yellow mosaic . Anthracnose , Cercospora Aphid Cruenta. Cercaspara cancscens Bruchid Bacteri a1 pustule, Web blight Moderately resistant Cowpea aphid-borne mosaic, Brown blotch, Scab, Bacterial blight Th ri ps SU5cepl ip ie Septaria Maruca, Co reid bugs Kamboinse 8adeggi ~. . ~ ':' , . : , .. " .. Mokwa . .~" .. ~ .. ~~.~ .. . .~ ~ .' . 0:::: 0 IIora += 8 Ilorin 0 ...J lle-Ite Samaru Kano Mean L---------~--f I---?--~-~---I o 400 800 1200 1600 2000 Yield (kg / ha) Figure 11. Performance (yield kg/ ha) of IT 845-2246-4 at different locations in 1986. 50 Screening Cowpeas for Resistance to Maruca Pod Borer Stem Damage The first part of the cowpea plant that gets , damaged by Maruca leslu/a/is, the maruca . ~ ... , pod borer (MPB), is the young tender stem, starting from the terminals down to the peduncles, main stem and branches . The ex­ tent of damage to stems due to MPB varies ,... lJ considerab ly between cowpea culrivars. A great dea l of variabi lity exists between I~ cowpea cultivars in the extent of stem T damage suffered. The resistance of the plant ''I.~ • _, ";~- to damage at the early stage of growth has ~... . -.t" the advantage of reducing the early popula­ tion of MPB. To detecl stem resistance in a reliable ~- . , ~ manner, a nd to study subsequently the mechanisms involved, a bioassay was design­ ed to infest young cowpea seedlings at the trifoliate stage in pots with 5, 10 and 20 (1-2 days old) larvae of the MPB per plant. Lar­ vae were obtained from laboratory cu lture. ~. ~ ~--.. Using a randomized co mplete block design ..... the experiment was replicated five times. Ten Typica l stem damage cll u~d by Maruca teslUlalis. the days after infestation, the test lines currently Maruca pod borer (MPH) . being studied were visuall y rated for damage (Table 13). susceptible check for nower and pod All cultivars were resistant or highly resis­ damage, showed resistance to stem damage tant using 5 and 10 larvae per plant. At 20 thus indicating that a given variet y or larvae per plant , one cultivar showed cultivar may not be resistant or susceptible defi nite susceptibility to stem damage and to a ll feeding damage by MPS (Table 14). another low resistance. IT 82D-716, the While population levels as high as 20 lar­ cultivar that is used convenlionally as the vae per plant may not be encountered under Table 13. Key for \'isual evalualion of slem damage by the MPB 10 cowpea seedli ngs. Damage Resistance rating Pla nt part and damage characteristics Index Highly resistant No visible damage to seedling 2 Resistant Slight damage to stem / terminal shoots 3 Low-moderate resistance Moderate damage 10 stem/ term inal shOalS 4 Moderately suscept ible Heavy damage 10 stem/ term inal shools 5 Susceptible Severe damage to stem/ terminal shoot s leading ullimately to wi ll ing and plant dealh 51 Table 14. Damage scores of selected cowpea culti\lars at seedling stage (5 trifoliate stage) using 3 levels of artificial in· festation with Maruca larvae in the sueenhouse, lIT A, Ibadan, 1986. Cultivar 5 larvae lO larvae 20 larvae MRx 2-84F 1.00 1.75 2.50 MRx 5·84F 1.67 1.25 2.35 MRx 49·84M 1.33 1.50 4.00 MRx lO9-S4M 1.33 1.75 3.25 TVu 946 (Resistant check) 1.00 2.00 2.00 IT 82D-716 (Susceptible check) 1.67 2.00 2.25 X 1.54 2.26 2.79 S.E. 0.11 0.50 0.30 Rvt 7.14 22.12 10.75 ilScale of 1·5. 1 = no damage; 5 = severe damage bRV = relative variation natural field conditions, this type of screen­ ing treatment would ensure that only the best cultivars are selected for ~tem resistance. The relative variation (RV) at 20 larvae/plant is within the accepted range for such studies. 52 Cowpea Pests in On-farm Trials Under Mixed Cropping Systems An integrated pest management program (IPM) for cowpea pests was initiated on a collaborative basis between the International Centre for Insect Physiology and Ecology (ICIPE) and the International Institute of Tropical Agriculture (llTA) . The program was designed as a component technology of on-farm research in cowpea production . Experiments in technology generation were conducted in Ijaiye (Oyo State), Bida (Niger State) and Minjibirr (Kano State), Nigeria to: • understand the current farming systems for cowpeas. • understand farmers' perception of insects as a major constraint to cowpea production. • establish levels of crop loss due to key Cowpea inlercropped with sorgh um in a farme r's field insect pests . in Kano, northern Nigeria . This crop combination has • determine appropriate in secticide shown much promise in tria ls conducted su far. technology for use in conjunction with host plant resistance. jibirr, sorghum and cowpea were intercrop­ • determine the role of intercropping as an ped. One half of each plot was protected adjunct to cowpea IPM . against insect pests by spraying with These experiments were conducted with Cypermethrin at fortnightly intervals. The the aim of designing IPM packages for preliminary conclusions drawn from these validation under actual farming conditions. experi ments were: Cow peas were grown as an intercrop at three • Intercropping may reduce cowpea insect locations and invariably as the minor crop pests popU lations, but this is insufficient planted for home consumption, with any ex­ to offset losses in grain yield. cess sold on the market. Most farmers • Sorghum/ cowpea intercropping seemed reported insects as the single most important more productive than sole cropping of constraint to cowpea production. No action either sorghum or cowpea or intercrop­ was taken against them because of cash con­ ping of cowpea with maize . straints, unawareness of control tactics • Relay cropping of cereal with cowpea is and/ or non-availability of insect icides. unsuitable for rainfed conditions in some Aphids, leaf feeding beetles, nower thrips parts of Nigeria. and pod bugs were highlighted as the most serious insect pests. Cereal/cowpea intercropping experiments were carried out in the three locations to determine their effects on insect populations and yield losses. In Ijaiye, maize and cowpea were intercropped while in Bida and Min- 53 Effects of Crop Residues and Tillage Methods on Cowpea Production in Sudan Savanna Mllizc and erota/aria inlercroPllcd as II preceeding crop residue Ireatment in Ihe Sudan slI\'annu. In the semi-arid regions of West Africa and the tillage methods in the second year. population pressures have forced farmers La Maize plants received NPK and N fertilizers change from traditional shifting cultivation at planting and one month after planting and fallow systems lO systems based on con­ respectively. Maize crop residues in plots in­ tinuous cultivation and reduced fallow. tercropped with maize and Crola/aria were Without the prolonged fallow periods of the removed after harvesting. Crop residues in traditional system. it is very difficult to no-till plots served as in situ mulch whereas maintain the required soil fertility in these they were incorporated in the soil in tilled regions. One of the ways to maintain and im­ plots. All plots received 50 kg / ha of P20 S prove fertility under current practices is before planti ng. through the use of crop residues and green The effects of tillage methods on soil manure. IITA scientists, as part of the chemical properties are shown in Table 16. SAFGRAD project in Burkina Faso, con­ No-till plots tended to have higher soil pH, ducted an experiment on the effects of crop organic maller, total N and available P than residue management and the use of green plOts plowed by oxen and traclOr. This is manure on cowpea production under various probably due lO the more complete mixing tillage methods. of residues with the soil that results from ox­ The experi ment was conducted Over a two en and tractor plowing and favors more year period and involved four tillage rapid decomposition of residues. Cowpea methods and six crop residue treatments performance, however, was not affected by (Tab les 15 and 16) . The crop residue differences in soil chemical properties or treatments were established in the first year tillage methods. 54 Tabl~ 15. Soil chemical properties as affected by soil tillage methods, Loumbila, Burkina Faso. o/(lOrganic matter pH 07(1 Total N Available P (ppm) Tillage methods 0--10 em 11-25 em 0-10 em 11-25 em 0-10 em 11-25 em 0-10 em 11-25 em Zero-ti!1age 0.76 0.62 6.3 6.2 0.03 0.02 6.56 1.39 Hand hoeing 0.86 0.67 6.5 6.4 0.03 0.03 6.75 1.93 Oxen plowing 0.77 0.62 5.8 5.8 0.D2 0.02 6.37 1.% Tractor plowing 0.72 0.56 6.0 6.0 0.02 0.03 6.61 1.84 Table 16. Effect of preceding crop treatments on co"'·pea performance in a soil tilla2;e methods experiment, Loumbila, Burkina Faso. Preceding crop Floral Flowering Maturity Seed treatments bud initiation l date!; (DAP) dath (DAP) yield l ; (kg/ha) Maize crop residues removed after harvesting 39.3 a 48.1 a 71.2 a 436 c Crotalaria cut at flowering (pure crop) 37.9 b 46.2 be 69.5 be 887 a Crotalaria cut at cowpea planting (pure crop) 38.1 b 46.8 abc 69.2 be 918 a Crotalaria cui at flowering (intercrop with maize) 38.2 b 47.4 ah 69.9 b 673 b Crotalaria cut at cowpea planting (intererap with maize) 37.8 b 47.2 abc 70.2 ab 704 b Maize crop residues relained in situ 37.7 b 45.7 e 68.5 c 921 a LSD (S 'I,) 1.0 2.6 1.0 175 CV ('I,) s 6 2.5 40 ! Means followed by the same letter are not statistically different at the 507(1 probability level. The effects of preceding crop treatments and chemical properties of the soil. on cowpea production are shown in Table • No tillage with in situ mulch is as good as 16. Cowpea seed yield appeared to be conventional tillage. positively associated with the amount of • Farmers in semi-arid zones of West Africa crop residues left in the field. Maize crop are contributing to soil degradation residues retained in situ led to early flower through the removal of crop residues from bud formation and early flowering and fields. maturity in cowpeas as compared with plots from which maize residues were removed. Other mulch treatments gave seed yields that were intermediate between the two maize treatments. The major conclusions of the study are: • Crop residues left as in situ mulch or for incorporation into the soil through tillage have a significant effect on soil produc­ tivi ty and cowpea yields. This is essentially due to beneficial effects on the physical 55 An Effective New Method for Screening Soybeans for Resistance to Frog-eye Leaf Spot (Cercospora sojina) Frog-eye leaf spot, a fungal disease of soy­ beans known worldwide but first seen in Nigeria in 1981, became widespread near Gboko, Benue State in the traditional soy­ bean growing area in Nigeria in 1984. By 1985, it was severe in seed multiplication fields in southern Kaduna State, another major area for soybeans; and in 1986, the disease was epiphytotic in soybean fields in central Kaduna State and was seen in breeding nurseries at Zaria and near Jos. The combination of susceptible cultivars and and warm humid conditions in Nigeria's growing season favors fungus growth and makes frog-eye leaf spot one of the most serious threats to expanding soybean pro­ duction in Nigeria. The disease also has been widespread in 1v ary Coast since 1982 and in Typical symptoms of frog ·eye leaf spot (CercQspora Cameroon si nce 1985. sojina) on soybean. A variely thai is resistant to frog·eye leaf spot (right) alongside a susceptible variely (left) . 56 Table 17. Lines showing no inf«tion of Cercospora 1.0) and will form the foundation of a cross­ sojina 91 days after planting and controls in a screening iog program to breed for resistance. The nursery, Samaru-Kalaf, Nigeria in 1986. scores are shown with controls in Table 17. Entry Cercospora Origin Score TGm 2090 1.0 Brazil AOS 126 1.0 Taiwan OC 6003B-4 1.0 Brazil 50269-7-6 1.0 Brazil TGx 1014--35E 1.0 llTA TOx lOll-IE 1.0 llTA TOx IOll-lE 1.0 llTA TOx I071-IOD 1.0 llTA TGx 536-02D (Control) 2.0 IJTA Samsoy I (Control) 4.5 JAR· Orba (Control) 2.0 CSA Bossier (Control) 2.0 CSA Jupiter (Control) 2.0 CSA Number of entries 354 Trial mean 2.9 Standard error 0.28 C. V. % 13.5 ... Nigeria In 1985, a trial was conducted jointly by Ahmadu Bello University, Zaria and UTA at Samaru-Kataf involving 354 breeding lines with two replications in a randomized complete block design. Through the use of spreader rows and susceptible varieties these lines were screened for resistance to the disease. Forty-five days after planting (DAP) frog-eye leaf spot was seen on all spreader rows and, at 63 DAP, the disease had infected most plots. Disease scores are on 1-5 scale: 1 no spots seen; 2 one or more spots on one or several plants; 3 some spots on most or all plants; 4 many spots on all plants; 5 all plants severely infected with loss of most photosynthetic area. A mean score of 3.0 or less indicates moderate resistance. An average score less than 2.0 indicates good resistance. Scores above 3.5 on this scale indicate unacceptable susceptibility. Of 283 UTA breeding lines and 65 in­ troductions, 183 had mean scores of 3.0 or less. Four breeding lines from UTA and four introductions from Brazil and Taiwan re­ mained entirely uninfected (mean scores of 57 A Laboratory Method for Evaluating Resistance to Pod Shattering in Soybeans One of the major problems associated with tified accurately and quickly before testing soybeans in tropical ecologies is pod shatter­ in replicated yield trials. Screening for ing when crops reach maturity in hot and dry resistance to shattering can begin' when conditions. Seed yield losses of 50 to 100 "70 Single Plant Selections (SPS) are taken from are often associated with susceptible segregating F4 and F5 populations during varieties if harvesting is not done within a the normal growing season in Nigeria day or two of maturit y. If, however, a varie­ (planting in June and July and harvesting ty has good resistance to shattering then in October and November) . When taking farmers can wait and harvest up to four SPS, plants that shatter at maturity are not weeks after maturit y without such yield selected . This method elim inates the SPSs losses. Therefore it is important that soy­ that are highly susceptible to shattering. bean varieties developed for farmers should In December, the SPSs were planted in have good resistance lO shattering in the 2-row plots (each plot has the seed from one ecologies in which they will be distributed SPS) in (kenne, Nigeria and grown under ir­ and grown. rigation. These plots mature in March when Soybean breeders at liT A have devoted the weather is warm and humid. In such con­ increasing research atlemion to resistance to ditions even varieties that are high ly suscep­ pod shattering in recent years. Efficiency in tibe to shattering do not shatter, so it is im­ plant breeding is always improved when lines possible to evaluate for resistance to shatter­ that arc good for a specific trail can be iden- ing in the field . A soybean variel y that is susceptible to pod shattering (left) cumpared (0 a va.-iet}' thai is resislanl (right) , 58 The following procedure has been This method has been very reliable and developed and is now being used to screen scientists have a high level of confidence in for resistance to shattering: its accuracy and repeatability. The repeatability of this procedure is verified by I. At the stage of maturity when pods are ANOV A (the probability of a greater F has light brown in color, 25 pods are been less than 0.000 1 for all 10 trials in 1986) carefully removed from each plot and and also by Kendalls coefficient of concor­ placed into a labelled paper bag. dance. 2. These samples are then stored at room The laboratory method is also highly cor­ temperature for 10-20 days. related with the field rating for shattering. A 3. Samples are then put into an oven set variety trial with 4 replications on 27 entries at about 300 C and the temperature is was conducted at 5 locations in 1985. The increased by about laC per day. laboratory method was used to evaluate 4. Each sample is inspected daily and if 13 shattering at lbadan and the field method or more pods have shattered, it is was used at the other 4 locations (Mokwa, removed from the oven and the date Zonkwa, Bukuru and Zaria). This (or days in the oven) recorded. laboratory screening technique has greatly 5. The longer a sample stays in the oven improved the efficiency with which new (without shallering 50"1. or more) the breeding lines can be evaluated for resistance better its resistance to shattering. to shattering. 6. Approximately the first 10% of the samples that shatter and are removed from the Oven are given a rating of 1, the second 10% a rating of 2, ". up to the last 10% with a rating of 10. 7. These data (1-10 rating) are then analyzed by ANOV A or by ranking the data and calculating Kendalls coef­ ficient of concordance which is free of any scale assumptions on the above 1-10 scale. 59 Annual Report Executive Summary Maize Research Program Nineteen eighty-six was a year of recognition for liT A's Maize Research Program. During the year,lITA received the 1986 King Baudouin Award for its research submitted as "Solving the Problem of Maize Streak Virus: A Research Breakthrough to Increase Maize Production in sub-Saharan Africa ." liT A was also awarded an honorary mention, accompanied by a si lver plaque, by the International Cul tural Centre for the Development of Peoples for its submission, "Stable, High-yielding Hybrids Developed by !ITA: The Key to Increased Maize Production in sub-Saharan Africa," to the Centre's first developmenL-tcchno)ogy competition . '"= " , .. ........ ~ "'-' ..... ,,--..,. ............0 Even more important is the increasi ng recognition coming to the program from national pro­ grams, seed companies and farmers throughout Africa. The number of trials requested from the program is continuously increasing. Twenty-four trial sets were requested by national pro­ grams in 1982; by 1986, the number requested had risen to 450. Ofl en, countries that have participated in international testing later request specific varieties from IITA for retesting and seed multiplication . Many requests were obtained during 1986. The most significant was the April shipment of 2000 kg of streak-resistant TZSR-W- I and 200 kg of streak-resistant TZESR-W to Ethiopia for the new reselliement areas, which are badly infested with maize streak virus. In Nigeria, breeder seeds of streak-resistant varieties are supplied to the National Seed Ser­ vice (NSS) for multipUcation and distribution. In 1986, streak-resistant varieties were grown on 250,000 ha. The NSS expects that by 1990, most of the two million hectares of maize in Nigeria will be seeded with streak-resistant varieties. During the year, seed of two new long-needed variet ies were also increased. The 500 kg of DMRSR-W produced by IITA in 1986 will be further increased by the NSS and Ondo State Ministry of Agriculture in 1987. The seed of this varie ty, which is resistant to both downy mildew and streak virus, will be distributed to farmers in Ondo State, where downy mildew is a serious problem. Seed of TZMSR-W, a variety developed for the mid-altitude where resista nce to Helminthosporium {urcicul11, Puccinia sorghi and maize streak virus is required, were given to a commercial farm in Jos Plateau (Nigeria). Part of the farm's production was purchased by the NSS for mUltiplication and for distribution to farmers in 1987. 60 Seed production of hybrid maize varieties is also expanding, and the area planted to these hybrids is growing. During the year, 35,000 ha were planted to hybrid maize varieties in Nigeria. About 1800 t of hybrid seeds were also produced during the year, which is enough to plant about 100,000 ha to hybrid maize in 1987. liT A-developed hybrids are also doing well in other African countries, three of which (Cameroon, Ethiopia and Ghana) are already ex· perimenting with hybrid seed production using inbred lines provided by lITA. Scientists with the program have continued to emphasize breeding for resistance in their research. Breeding for streak resistance is a major focus of the joint CIMMYT II IT A project established in cooperation with the University of Zimbabwe in 1985 for the development of germplasm for the mid-altitude ecology. Leafhopper-rearing facilities similar to those already established at lITA in [badan, Nigeria, were built in Harare, Zimbabwe, during 1986, and the lITA-developed infestation techniques were modified to fit the requirements of the differing ecology and climate of Zimbabwe. Toward the end of 1986, maize was infested with the virus in screening maize varieties for resistance to the disease. The results have confirmed that the resistance source developed at liTA is stable in Zimbabwe as well as in Nigeria. Through the use of this source, it is hoped that in a few years, a wider range of varieties and hybrids will be available for the mid-altitude ecology. [n 1985, program scientists concentrated on improving techniques of screening for stalk rot and in 1986, they concentrated on developing a reliable method of evaluating maize for its reac­ tion to ear rot. Of particular interest was the optimum time for infesting maize and the best position on the ear to infest. The technique developed was used to evaluate the reaction of elite inbred lines to the three major ear rot fungi: Fusarium moniliforme, Botryodip/odia theobromae, and Macrophomina phaseoli. Differences in responses of different maize varieties and hybrids to the storage weevil Sitophilus were observed in 1985. [n 1986, program scientists continued screening maize genotypes using quicker and more accurate laboratory tests. These tests have shown that there are distinct differences in the response of inbred lines to the storage weevil. Progress was also made during the year in developing reliable artificial methodologies of screening for resistance to the maize borer Eldana saccharina, with the results from artificial in­ festations being more uniform than those from natural infestations. Using these methods, it was possible to differentiate between different families and to identify germplasm with good levels of tolerance. liT A scientists believe that it will soon be possible to initiate a large-scale breeding effort to develop varieties tolerant to Eldana. Only limited progress was made during the year in screening for resistance to the Sesamia calamistis borer. Unfortunately. no progress was made in the breeding of maize for resistance to SUiga, a parasitic weed. For three years, natural infestations of Striga were heavy and relatively uniform in Mokwa, Nigeria, but in 1986, there was almost no infestation, which interrupted the screen­ ing of maize for Striga resistance. The view taken by the program that nature cannot be depend­ ed upon to provide adequate screening conditions and that reliable screening methodologies must therefore be developed has been reinforced by the 1986 setback. The hybrid project has continued its intensive work in using different sources of germ plasm to develop new inbred lines, the basic materials used in hybrid development. Emphasis was placed on correcting weaknesses observed in the first generation of inbred lines developed previously at liT A. The second generation of inbred lines is expected to produce better hybrids and to be more productive for the purpose of seed production. The project expanded its efforts 61 to develop three-way and double crosses, and it continued testing hybrids in research plots and in farmers' fields throughout Nigeria. During 1986, the National Accelerated Food Production Program (NAFPP) staff were more deeply involved in the on-farm testing, and by 1987 they will assume major responsibility for the on-farm trials. During 1986, a number of promising hybrids that are adapted to the mid-altitude ecology and that are resistant to maize streak virus, H. turcicum and P. sorghi were identified. These hybrids will be produced commercially after an additional year of testing. In addition to being used as the basic breeding materials for hybrid development, inbreds can also be used as basic breeding materials for the development of open-pollinated synthetic varieties. During 1985 and 1986, a number of synthetics were developed at lIT A and tested in several locations in Nigeria. The performance of these synthetics is very promising, especially in comparison to the performance of the best available open-pollinated varieties. Three of the syn­ thetics will be included in the international trials offered by lIT A in 1987. Inbred lines are also very useful in developing and identifying homozygous and uniform sources of resistance to pests, diseases and other constraints. Through thorough testing over the last few years, lines with a high level of resistance to diseases such as maize streak virus, maize mottIe, H. /urcicum, P. polysora, Curvularia spp., downy mildew and ear and stalk rots have been identified. Similarly, several lines with tolerance to Striga hermon/hica and drought have also been identified. liT A's involvement with the SAFGRAD project in Burkina Faso continues. The amount and the distribution of rainfall in the country during 1986 were generally good, although July was somewhat wet. In the breeding program, families of the drought-resistant Pool 16 population were evaluated under two levels of drought stress. The population is now being advanced to C2• Project scientists continued to evaluate other genotypes for drought tolerance. Progress was also made in the development of extra-early genotypes (less than 82 days to maturity). In addi­ tion, research on tied ridging and other water-saving cultural practices showed that tied ridges can be detrimental to maize growth if the early part of the rainy season is very wet and water does not infiltrate below the topsoil. Additional research is needed to determine the best management practices for tied-ridging systems. In Cameroon in 1986, a lowland variety extensively tested by llTA scientists under the NCRE Project was recommended for release. This is the sixth variety that has been recommended for release since the project started in 1982. These varieties have been introduced from interna­ tional (lITA-CIMMYT) populations. New lowland varieties developed by the lRA-NCRE pro­ gram and hybrids from llTA are currently in advanced testing. The first major tests of mid- to high-altitude maize hybrids were completed during 1986, and a few of the hybrids were pro­ moted to advanced testing. Also during the year, reciprocal synthetics were formed from first­ cycle inbreds and a large number of new inbreds were extracted. The final recombination of parents for the new populations was made, and recurrent population improvement and variety formation will be initiated in 1987. With regard to maize agronomy in Cameroon, project scientists in Garoua found that even though rainfall was good there in 1986, there was a significant increase in maize yield in response to tied-ridging. Additional information on research activities referred to in this summary is available in the Annual Report of the Maize Research Program. 62 Maize with Combined Resistance to Downy Mildew and Maize Streak Virus Available to Farmers Downy mildew (Peronosc/erospora spp.) is a resistance to the two diseases has been im­ serious maize disease in Zaire, Nigeria, proved a nd sustained through shuttle Mozambique, Somalia, Ethiopia, Sudan, breeding between two locations (Owo, Benin, Zambia and Southern Africa . In all Nigeria. for downy mildew resistance and these places, maize streak virus is also a pro­ Ibadan, Nigeria, for streak resistance) . duction constraint. Downy mildew and In addition, the downy mildew- and streak are both systemic, and subsequent streak-resistant (DMRSR) populations have development of a plant is severely affected been improved for grain yield and desirable once the plant is in fected by either disease. agronomic tra its through multilocational Plants infected by either of the diseases family test ing. In tests conducted in eight within three weeks of planting are killed or countries, the DMRSR entries performed as stunted or become barren, resulting in 1000/0 well as or better than the entries only resis­ yield loss. tant to streak (Table 18). A collaborative project was established DMRSR populations have been offered to between the National Cereals Research In­ interested national programs for use as stitute in Nigeria and lITA for developing breeding materials or for further testing and maize varieties wi th combined resistance to direct use by farmers. In Nigeria, farmers in downy mildew and streak (see IlTA the downy mildew zone have enthusiastically Research Highlights /984). Combined requested seed of DMRSR maize. Five hun- •,. " ..I. !' l 'i. ' ,_~~; c,~"~-\f.~~.,~,%t: ", .. \ '. :.'r t";.,~' ;~',;,~~ ". '\". "'1~?! .~~~I 'VI. .." , " - . ~. I':';;;:~ , '~\_: ,5 ....::r,~ . .;.;~. :;",,/ "~;"~ ',-"",, 7' I #;i":-;~_'~"1& \ . "..:-~ ,~,' " . ., r ",., "*~' / . ,",. ---....I " .(-1. :"-1~.;.~ } I' :... . ':.1. 1', r I.', , "r ~. "~"","" "'" .;/,.'..' , .~.~~ /') .. ~;.:;~~ ,~~ I, I -,,/ ..... . ....~ .,~ '--- ~ ...- , . , j ....... ' 'r" //'" Downy mildew in a heavily infested farmer's field . The Downy mildew in research plots . The susceptible lines in few dark-green plants in the background are the only the cente ... have nanower and pale ... leaves than the resis­ ones that escaped infe<:lion . tan I lines in the foreground. 63 Table 18. Performance of down)' mildew- and streak­ dred kilograms of the resistant maize was in­ resistanl nrieUes DMR·ESRW and DMR-ESRY and of earl)'- and inlermediate-maturing, streak-resistant creased in 1986 and will be provided to the varieties auoss 26loeatioDs in eight countries, 1985.1 Ondo State Government (Nigeria) for fur­ ther multiplication and distribution to Grain yield, Days to farmers. Entry t/ha 50070 silking The availability of such varieties is a DMR-ESRW 3.6 54 significant step toward offering farmers EV 8449-SR Be, 3.5 56 maize that is resistant to multiple diseases. DMR-ESRY • 3.4 54 Such varieties will safeguard maize farmers EV 8430-SR Be, 3.3 51 from the vagaries of the tropical environ­ EV 8435-SR Be 3.3 55 4 EV 8431-SR Be, 3.2 50 ment, and the farmers will therefore be en­ Across 82 TZESR-W 3.2 54 couraged to invest resources for greater pro­ Pool 16-SR BC4 3.1 50 ductivity and increased production. lBenin, Burkina Faso, Cameroon, Ghana, ~ali, Nigeria, Sierra Leone and Zaire. 64 Synthetic Maize Varieties Developed One of the advan lages of open-poll inaled In 1979, lI TA began developing inbred varieties is that farmers can save seed from lines, which are used in the development of lheir harvesl for planling in the nexl year. hybrids. These inb red lines are lhoroughly This is one of the reasons farmers in Africa lesled for lheir combining abililY during are growing open-pollinated varieties. their development , and they can be used Therefore, the development of such varieties 10 produce synthetic varieties. Two major forms a major pan of the research under­ heterolic groups identified by the scienlisls­ laken by the maize program. lropical germ plasm (Tr) and lemperale­ Until recently. only composite varieties derived gennplasm (Te) (formed by crossi ng were developed lh rough recurrent popula­ lemperale and lropical germ plasm and lhen tio n improvemenl. The genotypes used in selecl ing for lropical adaplalion) - have forming composite varieties are selected for been used LO produce lhree lypes of syn­ lheir perfo rmance in yield lrials. However, lhetics. The Tr and Te synthelics are used in sy nthetic varieties are form ed from developing new lines; the (Tr x Te) synthelics genolypes (usually inbred lines) selecled for were developed for use as open-pollinal ed lheir combining abililY and are lherefore ex­ varieties. pecled LO have a higher yield pOlenlial lhan During 1986 , a lria l consisling o f syn­ composi te varieties. thetics, hybrids and composite va rieties was A te mperate-derived line (/e/I) and Iro pical line (right) used in producing synthetic maize \'ariclies. 65 Table .9. Performance of hybrid , s)o·nlhetic . composite and impro\'ed local "'aridies across four locations in Nigeria .- Yield, Days to 50'70 Plant Ear Lodging' tlha Silking height, height, Type of variety2 Name em em Root Stalk Hybrid S.c. 8321-18 6.50 55 225 117 L2 1.2 Synthetic Syn. No . I (TrxTe) 5.38 55 210 104 1.5 1.3 Composite lkenne 83 TZSR-Yl 4.86 57 232 115 L7 1.4 Improved local Western Yellow 4.03 59 246 152 2_2 2.9 llbadan (two locations), Ikenne and Samaru . 20nly th e best entry fro m each type is included . There were 20 entries in this trial. 31 = resistant; 5 = very suscepti ble . conducted at four locations in Nigeria. The Table 20. Perrormance of tropical (Tr), temperate­ hybrid 832 1-18 was the highest-yielding en­ derived (Te) and tropical x temperate-derived (Tr x Te) try across the four locations. Among the synthetics in (he forest and savanna ecologies. synthetics, Synthetic No. I (Tr x T e) was the Germplasm Yield. lIha highest -yielding (Table 19). Of the Com­ Synthetic sources posites , Ikenne 83 TZSR-Y-I was higher­ Forest Savanna yielding than EY 8443-SR and Gusau TZB. Syn. No. t Tr x Te 4.5 8.0 Syn. No. 2 Te 4.1 6.8 "-'estern Yellow was used in these trials as an Syn. No.4 Tr 4.6 6. 1 improved local variety. Of the four types of varieties tested, the derived germ plasm is not as yet fully adapted hybrids were the highest-yielding. Yields of to the more hum id tropical forest environ­ the ot her types as a percentage of the hybrid ment. Better adaptation must be pursued if average yield were 830/0 for synthetics, 75% the excellent poten tial value of the for composites and 62% for the improved temperate-derived germ plasm is to be local variety. These results closely agree with realized. expected results. In 1987, synthetic varieties will be includ­ Not only were the synthetics higher­ ed fo r the first time in the international yielding than the composites, but they also variety trials offered by the maize program. had better agronomic characteristics such as Additional synthetic varieties will be pro­ plant height, ear height and resistance to duced as new inbred lines are developed. root and stalk lodging (Table 19). Such synthetics will enable farmers to obtain Synthetics developed from tropical and higher maize yields than they now get with temperate-derived germp lasm performed their composite varieties. differently in forest and savanna ecologies. In the savanna, the heterosis between the tropical and temperate-derived germ plasm was fully expressed, and the yield of the (Tr x Te) was the highest among the three types. In this ecology, yield of the temperate­ derived synthetic was better than that of the tropical one (Table 20). In the forest zone, however, yield of the tropical synthetic was better than that of the temperate-derived one and was as good as that of the tropical x temperate-derived synthetic. These results confirm previous findings that temperate- 66 Maize Streak Virus Screening Methodologies for the Mid-altitude Ecology Maize is a major cereal crop in sub-Saharan Africa, and it is a staple food in Kenya, Malawi, Zambia, Zimbabwe and other ADULTCA6E I countries in East and Southern Africa, Disease is a major cause of the low yields of '\ \ lhis importanl crop, and maize st reak virus (MSV) is one of the most yield- limiting diseases on the continent. Over a period of 10 years, llTA research­ ers have succeeded in developing streak· resistant maize varieties and hybrids for the lowlands. Only o ne p opulation, however-TZMSR (streak·resistant)-is suitable for the mid·alt itude ecology (800- 1500m) that covers much of East and Leafhop per-rearing facilities al the Mid-Altilude Maize Research Slation at Harare , Zimbabwe. Southern Africa. In 1985, CIMMYT and ~ 'I' "'" , I ,' <"'~\~,~~. ~07ff;~~~(:i,t;>~;~~;~: '/;:! ~ 'f, , ,,' rill\: ,','" , " ~v· , -. ,. ' " .. i,.. 'r'" ~ l' " _ 1 ~I ,t','. ' l iTe, ~~ ~ : ,,'), ' · ' ;yt ~''' .. \''·l I',~-" ~~'; r :~:·~~'~'L I , /', • A, ' ,t4! .-, ' ' : -' - -l~ ·'· ;,: ), ' ! .. : : ... ., ~!: .7' ~j ~'h'I .r. ~.: .;.;- . ..-; ..;..,-~:, I 1. '· -,.OJ" ,10', . ...... -_)~.1_.":. .,'.,-,,.,'.\ ~k"A,.) I ,~-nc.,.. ...... \ .~ t; - .~"'-t~~'rJ.: "1 ~~ .. • ....~: ,~:.,. ~,=k~~: .,' : ""'f'_.\~~. ',: ... ~.(..1": -:-;. ~~·.t,.:-.<;...~~ ~ii ' .. ~/.-~.1" --..~ -. ," , _, _' A,~ " , '\ '_ i-" f-' . .J':"' __ ~~(, t, . ~-",=i '" .- 'I . -- If"-i.· J" " ~ '. ,~T - .. /~~-,-- ... '10. ''c. '" i " f't:f';'~Jt-~..rr-. ..•. ,. . ~:.u.~'. _- ... - :t< .. "'''';~ -''''''', .J t- ...... \ -, _:.;~'Io '< ....." .: -1.."'. ... -' , - . :-,. ...~ I f ~ ". ', ,-- .-' <"'-', ,;<, , I - '\: .. ~; I ' ," ' • - - ' _'~" ,~. ,l - .,"-'- ... .,.. . '/ -.. , "",_"r'..1~"',<"_ _ , 'fA, .'~ ,,;y·/ ~ ::- - :.~.J t' '" ., '\ A' ...' ~ -. _ " .. . ~. - . ' , Workers artificiall y infesl maize plan Is with maize streak virus by releasing disease~arrying leafhoppers onlo plants in experimenlal fields . 67 lITA in cooperation with the University of of leafhoppers must be reared during the Zimbabwe established the Mid-Altitude winter (in heated greenhouses) so that many Maize Research Station at the University maize plants can be infested in a short farm in Harare for the purpose of develop­ amount of time when the rains begin. ing maize germplasm suitable for the mid­ Egg-laying and nymphal development of altitude ecology. the leafhoppers at the two sites also differ. Cicadulina spp. leafhoppers are the vector C. triangula (the leafhopper species reared at responsible for transmitting MSV to healthy Ibadan for transmitting MSV) prefers to lay maize plants. The most prevalent leafhopper eggs on millet while maize is a more ade­ species at the new station is C. mbila. Initial quate host for nymphal development. C. activities at the station included confirming mbila prefers maize for egg-laying and millet that C. mbila is the leafhopper species most is a better host for nymphal development. efficient at transmitting the disease under the Low temperatures at Harare affect the ger­ mid-altitude conditions. mination of the maize and millet plants used The basic methodologies for screening for leafhopper-rearing. This problem has germ plasm for streak resistance had already been overcome by the use of plastic mulch to been established by researchers with IITA in raise soil temperature. Nigeria, but the methodologies needed to be The techniques developed at Ibadan for modified to adapt them to the conditions MSV screening have been successfully found in Zimbabwe. Unlike at Ibadan, adapted to the mid-altitude conditions at where leafhoppers can be reared and maize Harare. In mid-December 1986, 850 rows of can be grown year-f\l>und, the winter at S2 maize seedlings were infested with 80,000 Harare is too cold for more than one crop of C. mbila adults. An additional 470 rows maize a year. Consequently, a large number were infested three weeks later. 68 Biological Control of Aphids in Leafhopper-rearing Cages Because maize streak virus (MSV) is one of vaded the mass-rearing cages. Large popula­ the most yield-limiting diseases of maize tions of the aphids had developed with the throughout Africa, screening of maize for cool temperatures and the low relative resistance to the disease is one of the major humidity of the wi nter months coupled with objectives of the Mid-Altitude Mai ze the abundant wheat (which serves as a host Research Station located in Harare. Zim­ for aphids) in fields at the station . babwe. At the station. Cicadulina mbila. the The aphicide Pirimor could not be used to leafhopper vector that most efficiently control the aphids because it also kills transmils the disease to healthy maize plants leafhopper nymphs . The aphids. however. in mid-altitude regions. is being mass-reared could be controlled biologically . In the mass­ in cages for use in screening maize breeding rearing cages. an unidentified beetle (orange materials for MSV resistance. and dark-brown coloration on the elytra) The mass-rearing of the C. mbila leafhop­ was observed preying upon the aphids. A per was interrupted in June and July 1986 wasp also found in the mass-rearing cages when aphid s (Rhopalosiphum maydis. was parasitizing the aphids, with oviposition Schizaphis graminum and Silobion sp.) in- and development of the eggs taking place A Chilomenes sp. larva feed ing on an aphid . An adull wasp emerging from a parasilized aphid. 69 within the aphid and the adult wasps emerg­ Biological means will be used to control ing three to four weeks later, leaving mum­ aphids in the future. The greatest control can mies of the aphids. be achieved with Chilomenes sp. in combina­ Two polymorphic beetles-Chilomenes tion with the wasp. However, the rearing of sp. and an unidentified species-found in the wasp is difficult at present. Until the wheat and oat fields were also observed wasp can be reared more easily, Chilomenes preying on the aphids. Chilomenes sp. larvae sp. in combination with the unidentified consumed an average of 20 aphids in less polymorphic beetle will be used to control than 10 h. Adult Chilomenes sp. consumed the aphids. an average of 20 aphids in 17 h. These high With the biological control of the aphids, predation rates, however, occurred only the mass-rearing of the leafhoppers can con­ when the aphid populations were high. tinue, ensuring that adequate numbers of the Under low aphid population densities, the vector will be available to infest maize in searching ability of both larvae and adults screening for MSV resistance. was poor. Chilomenes sp. was more efficient than the unidentified polymorphic beetle in con­ trolling the aphids. Chilornenes sp., however, attacked leafhopper nymphs at a greater rate than did the unidentified species. Thus, Chilomenes sp. was used initially for aphid control, with the unidentified polymorphic beetle being used when the aphid population became low. 70 Inbred Lines as Uniform Genetic Sources of Resistance One of the major responsibilities of the in a number of ways. one of which is as Maize Research Program at lIT A is to sup­ uniform genetic sources of resistance in their plement the breeding efforts of national pro­ breeding programs. grams by providing them with useful germ­ After eight years of intensive research and plasm . Diseases, insects and other con­ screening for resistance, the' maize scientists straints are widespread and pose a constant have developed uniform inbred lines with threat to the farmers' maize crops. Given the stable, high levels of resistance to various climatic and socioeconomic environment of constraints. The lines showing the highest the farmers, the use of resistant or tolerant levels of resistance to the major constraints varieties is the most viable of the control op­ are listed in Table 21. tions. Therefore, the program scientists con­ The derivation of these lines and some of centrate their efforts on resistance breeding. the lines' characteristics are listed in Table The development of the techniques for the 22. controlled inoculation and infestation of All lines developed at liT A show maize has led to uniform screening condi­ resistance to maize streak virus (MSY), to tions needed for such breeding to be suc­ rust (Puccinia po/ysora) and to blight cessful. (He/min lhosporium maydis). Each line also In 1979, the Maize Research Program ini­ has high levels of resistance to other con- tiated a line-development project , the pur­ pose of which is to develop vigorous, Table 21. Tropical maize (Tzl) lines resislanl 10 or tropically adapted inbred lines that are resis­ tolerant or some important production constraints. tant to diseases, insects and other research­ Production constraint Resistant / tolerant lines able ecological constraints. The lines developed can be used by national programs Foliar diseases Maize streak virus All Tzi li nes '" i J (best: Tzi 3. 9. 12) Puccinia polysora All Tz-i lines (best: Tzi 3, 4 , 7) Helminlhosporium maydis All Tzi lines (best: Tzi 17,25 , 35) H. lurcicum IOI-TZMSR Curvularia pallescens Tzi 4. 35 Downy mildew Tzi 25, 35 Stalk rOIS Fusarium moniliforme Tzi 3, 7, 18 BOlryodiplodia Iheobromae Tzi 3, 18,25 Macrophomina phaseoli Tzi 3, 7, 18 Ear rots F. moniliforme Tzi 3, 4, 17 B. Iheobromae Tzi 4, 28 M. phaseoli Tzi 3, 7, 28 Srriga hermonrhica Tzi 9. 12 Sesamia (slem borer) Tzi 4 Weevils (Silophilus spp.) Tzi 7, 15, 18 The uniform reaction or an inbred line thai is suscepti­ Drought Tzi 9, 35 ble to H. turcicum (lefl) and of one thai is resistant Lodging Tzi 9, 25 (right). 71 Table 22. Plant maturity, grain characteristics and origin of lines resistant to multiple diseases. Original Grain Grain Plant Inbred code no . Derivation color l texture2 maturityl Tzi J 1368 Across 772 1 x TZSR W fld m Tzi 4 1393 Guana Caste 7729 x TZSR W f I Tzi 7 2096 TZB x TZSR W f I Tzi 9 5012 Sids 7734 x TZSR W d/ f m Tzi 12 9030 28 x TZSR C d/ f I Tzi 15 9071 28 x TZSR W d/ f m Tzi 17 9091 RppSR(TZ) W fld m Tzi 18 4001 Sete Lagoas 7728 x TZSR Y f ml Tzi 25 9450 873 x RppSR Y d m Tzi 28 9499 F44 x RppSR Y d/ f m Tzi 30 9848 Hi29 x RppSR Y d/ f m Tzi 35 Ku 1414-S R Ku 1414 (Thailand) Y f ml I \V :: white; C = crea m: Y = yellow . 2d = dent: f = nint . 3m = medium: I = late . st raints. Inbred line Tzi 4 (1393), for exam­ ple, is resistant not only to MSV , rust and blight , but a lso to stalk and ear rots caused by Fusarium maniliforme, Botryodiplodia theobromae and Macrophomina phaseoli, and it also has some resistance to the Sesamia stem borer. Lines Tzi 3 (1368) and Tzi 17 (9091) possess the resistance common to all IITA-developed lines as well as resistance to stalk rots caused by the three rot fungi and to ear rots incited by F. moniliforme and M. phaseoli. All liT A lines are avai lable upon request 10 national programs in Africa. Unlike susceptible line 9089 (I~JI), line 4001 is resistant 10 Fusarium ear rot (right) Ilnd can be used as a source of resistance to the disease. 72 Screening and Breeding for Resistance to Eldana saccharina Eldana saccharina Walker. a postnowering important components of this work. A s pest of maize, occurs in almost all cQllmries many as 70.000 Eldalla eggs can be produced of sub-Saharan Africa. In many African each week at the peak of the production cy­ countri es , Eldana is the dominant stem borer cle. which is enough to infest about 1000 at the time of maize harvest. Females of this plants and to screen breeding materials stem borer lay their eggs on dead plant tissue routinely. or on debris lying on the soil. Larvae Maize plants are artificially infested a t penetrate the stems and feed there, and some nowering time with 80 eggs at the blackhead larvae eventually move to the ears. Yield is stage (one day prior to hatching). The eggs reduced through direct damage to the ears are placed between the leaf sheaths at the and through the reduction in the transloca­ level of the ear node. At harvest. infested tion of nutrients to the ears; in addition, the maize sta lks are split open and the follow ing stalk is weakened and becomes more suscep­ assessments made: the percentage of the tible to lodging. Eldana has been fo und to stalk below the ear that shows tunneling. the reduce yields (grain weight per plant) by 20 percentage of the nodes below the ear that to 2607. (natural and artificial infestations. show borer damage and the percentage of respectively). Feeding by Eldana also makes grain consumed or damaged by the borer the plants more vulnerable to ear and stalk (I = 0-6 070 kernel damage and 5 = 76-100070 rots. kernel damage). In addition. notes on stan­ Recognizing the importance of this insect , dard agronomic characters and on level o f scientists with the Maize Research Program stalk rot are made. By using this method. have begun to screen and breed for numerous breeding materials have been resistance to Eldana. Mass-rearing of this screened and significant differences in stem borer and the development of uniform Eldana. damage have been found among the and reliable screening methods have been materials . Of the breeding material s ~" .,~ ;! .• '~' . .' ~" . . "". _, ' I... · ·fJ' " ' • ,' __ '" ,o,-'!'" '. , :M-" :.,.'-,.. . ~.' _.~ . .. , :..''. ..<. .• (. . 7• ,_~.~i:.'.. ; .. ,'- \-•. -~ \~, "'\ ,/ ./ ·... ....l ·~'\.. , · t \ . . " . I. V ~ _ . __ . r -S. ,A: , ." - ",-,, \...,;.:---_~~I\ " _ ", '~' ,_~..;./ -'1f"':"~ . "",.,~.~ 1----- ... "k. . . ~.. .. . 't_ f~' I~ ;. ',' ~' ~.t',",~'rl' ~\t ,_ ' _" ~.~ ~Z~ -"': , ",-~~'! " ~.,," . "- :."-.. ~-" ~ .~. ~- .~,~~,, Maize plants afe artificially Infested with egg masses of Eldano saccharillQ (le/t) . The larvae feed on stems (center). The damage caused by the larvae weakens the stalks and makes them more susceptible 10 lodging (right) . 73 Table 23. Damage caused by Eldana saccharina to artifkially infested maize plants, Ibadan, Nigeria, 1985, 1986. No. of nodes bored oro stalk tunneling l)Jo stalk breakage Entry 1985 1986 1985 1986 1985 1986 5 best entries (mean) 2.6 1.8 8.3 13.7 6.4 26.6 4 worst entries (mean) 3.7 2.6 36.5 16.2 13.9 59.0 Check (8338-1) 2.9 2.5 16.1 19.3 6.6 33.0 screened in 1985, five with low levels of resistance and good stalk quality. The most damage and four with high levels were tested resistant lines will be screened and reselected again in 1986. In both years, the five best en­ again to verify their resistance, backcrossed tries showed lower levels of damage than did to the original introduction and then inter­ the four worst entries and the check (Table crossed to form an Eldana resistance pool. 23). With the progress achieved in screening The germplasm screened in 1985-86 is a methods, the maize scientists believe that the collection of introduced lines that have level of resistance to Eldana can be shown resistance to other stem-boring in­ significantly improved in this pool. sects. Many of these lines are from temperate regions and are thus unadapted to the tropics; all are susceptible to maize streak virus. In order to obtain sufficient streak resistance and tropical adaptation, all the introductions were first crossed to hybrid 8338-1, which is a single-cross, streak­ resistant hybrid with good root-lodging 74 Inbred Lines Tolerant to Drought Identified Drought is one of the most important factors Nigeria, during the first growing season of limi ting maize production in Africa . It can 1986. Scientists at the station took advantage severely reduce maize yields in the Guinea of the opportuni ty to evaluate the drought savan na, and in the drier Sudan savanna, tolerance of more than 120 inbred lines drought can lead to the lossof the entire crop. a lready being grown. Leaf rolling and plant liT A's research efforts on drought are con­ wilting were used as the major evaluation centrated with the SAFG RAD project in criteria. The uni formity of inbred lines drought-prone Burkina Faso. Major ac­ enables differences among lines to be easily tivities there include evaluating the effect of detected, and the most tolerant and most agronomic practices on soil water conserva­ susceptible lines were identified . tion, developing early-maturing and extra­ The most tolerant line was Ku 1414, a early-maturing varieties that will escape downy mildew-resistant line developed by drought, and screening lines for drought the Thailand National Maize Program. Two tolerance. IITA-developed lines (5012 and 9499) also Although drought in the forest areas is showed high levels of tolerance. The most usually not a serious problem, drought con­ susceptible lines were 5057 and Mo 20w. ditions can be created if the rainfall is not Some of the most tolerant and most well dist ributed thro ughout the growing susceptible lines were tested in the second season. This was the case at lITA in Ibadan, season in Ibadan and at Anadariya Farms Plants of linc 5057 und!;',. dmught st ress . No te the ro il­ Differences observed in leaf ro lling under greenhouse ing of the leaves. conditions owin g to moist ure stress in maize lines 5057 (susceptible) and Ku 1414 (drought tolerant) . 75 Ltd. (near Kana) under normal field con­ Table 24. Drought-tolerance ratings of the most tolerant ditions and also in the glasshouse (at Ibadan) and most susceptible maize lines identified at [hadan in the first season of 1986. under controlled moisture conditions in order to verify their performance. In the Drought-tolerance rating l glasshouse study, beginning 40 days after planting, maize plants grown in pots (one Variety IbadaniKano mearr Glasshouse plant per pot) were subjected to a 2I-day Tolerant period during which no moisture was ap­ Ku 1414 t.7 1.5 plied. Results from the glasshouse experi­ 9499 2.2 2.5 ment were very similar to those obtained in 5012 2.1 2.0 field experiments in Ibadan and Kana (Table Susceptible 24). 5057 3.7 4.5 Maize lines Ku 1414 (drought-tolerant) ANT-C-S5 3.9 3.5 and Mo 20w (drought-susceptible) were Mo2Ow 3.B 4.5 tested in a second glasshouse experiment I} = tolerant; 5 =: very susceptible. designed to measure specific plant responses 2Mean of ratings taken at lbadan during the first and to drought under similar stress conditions as second seasons and at Kana during the second season. in the first glasshouse experiment. Differences between the two lines in The 1986 field tests in Ibadan and Kana response to drought stress were evident. were conducted under natural conditions. In During the 21-day stress period, stressed Ku 1987, additional tests will be conducted in 1414 plants had a 25'l'. lower increase in [kenne, Nigeria, under controlled irrigated plant height and a 14'l'o lower increase in leaf conditions during the dry season. In these area than the unstressed plants. Plants of tests, a wider range of materials will be ex­ Mo 20w were much more affected by stress, posed to a range of drought-stress conditions with increases in plant height and leaf area in order to identify additional tolerant germ­ for the stressed plants being less than half plasm. those of plants not under stress. The daily amount of water transpired by stressed Ku 1414 plants was less than that transpired by stressed Mo 20w plants, even though Ku 1414 plants had more leaf area through which water could transpire. Per square centimeter of total leaf area, however, transpiration for Ku 1414 (0.06 mllcm2 daily) was four times less than that for Mo 20w (0.24 mllcm2 daily). 76 Annual Report Executive Summary Rice Research Program Consumption of rice in Africa is increasing rapidly. Rice production on the continent has also been increasing, with the increases coming from larger amounts of land being cultivated to the crop rather than from improvements in unit yields. Scientists in the Rice Research Program are studying ways of increasing unit yields through the development of high-yielding lines that are resistant to diseases and insects and to iron toxicity, drought stress and other environmental constraints. They are also devising management practices that are appropriate for the major rice-growing ecologies of Africa. In addition, the program participates in the International Rice Testing Program for Africa (IRTP-Africal, through which varieties from around the world are tested for their performance in Africa. In 1,}86, several thousand breeding lines were screened for leaf and neck blast, and those that were susceptible to the disease were discarded. Studies have shown that water-soaked blast lesions produce more conidia and produce them for longer periods than do lesions that are not continually wet. Conidia production of water-soaked lesions is especially a problem when nitrogen fertilizer is applied at high rates. Better disease resistance in high-nitrogen en­ vironments needs to be developed. Also during the year, 2024 breeding lines were tested for tolerance to rice yellow mottle virus (RYMV) disease, 125 of which showed satisfactory tolerance. Although serological tests showed that plants of the tolerant lines contained the virus, the plants exhibited no visually detectable symptoms of the virus and suffered no damage. Breeders and virologists have worked together to identify sources with greater levels of resistance to R YMV. Oryza g/aberrima accessions with high levels of resistance to the disease have been identified. These accessions have been crossed with O. saliva in order to incorporate the resistance of O. glaberrima into sativa lines. In addition to screening lines for resistance to diseases, program scientists are also screening lines for resistance to insect pests, including the stalk-eyed fly, the gall midge, lepidopterous stem borers and the grain storage moth. Specially designed screening techniques that are simple and reliable have enabled the scientists to identify sources of resistance. Two lines tolerant to the pink stem borer have been identified. Environmental constraints to rice production were also studied in 1986. One such constraint in high-rainfall areas is iron-toxic soils. Program scientists are screening numerous lines for their tolerance to iron. As part of the IITA-WARDA-CARI collaborative project on iron tox­ icity, a screening technique has been developed in which cement beds are used to precisely con­ trol water. The technique ensures uniform screening conditions under which toxicity reactions of test lines can be compared to those of the resistant check (Suakoko 8) and the susceptible check (lR 26). The cement-bed technique is easier than pot-screening and gives more uniform screening conditions than field-screening. 77 Mat Candu is one variety that has been identified through all three types of screening as being highly tolerant to iron. This variety also possesses other traits that make it superior to Suakoko 8 and Gissi 27, currently the best iron-tolerant varieties. Drought stress is another environmental constraint. During the year, 1500 rice lines and varieties at the vegetative growth stage were screened for tolerance to drought and for recovery from drought stress. In addition, 22 selected varieties were screened at the flowering stage. In these studies, varieties ITA 257 , ITA 301 and ITA 315 have shown tolerance to drought. Deficiencies in certain nutrients can make rice plants more susceptible to disease and other stresses. Silica deficiencies, for example, have recently been linked to grain discoloration. Field and laboratory studies have shown that grain discoloration, primarily a problem of upland rice, can be significantly reduced through applications of silica. Deficiencies in potassium lead to more severe problems with iron toxicity than would other­ wise occur. The symptoms of iron toxicity in susceptible varieties can be greatly alleviated by adding potassium sulfate to the soil. For iron-tolerant varieties such as ITA 249, near-normal growth is obtained, even in highly toxic soils, when sufficient amounts of potassium are supplied. Lines selected from the breeding program are screened by the rice-quality laboratory to eliminate those with undesirable grain quality. Parboiling method, cultural and management factors, postharvest handling, incidence of grain discoloration and other factors that affect grain quality and milling yield were also studied. In addition to the breeding and screening of lines for tolerance to biological and environmen­ tal constraints, scientists also test UTA elite lowland and upland rice varieties under different ecological conditions. Results indicate that many of the elite varieties are suited to a narrow range of growing conditions. Among the elite upland varieties, ITA 321 was consistent­ ly high-yielding. Program scientists are also testing elite lines under varying levels of manage­ ment, including rates of fertilizer application. They have found that for upland rice, a fertilizer application rate of 60 kg Nlha is optimum. The relationship between blast incidence and nitrogen application is also being studied, and for lowland areas transplanted with old rice seedlings, which is common in Africa, methods of nitrogen fertilizer application are being in­ vestigated. Results of international tests conducted through the International Rice Testing Program for Africa (IRTP-Africa) have indicated that varieties developed outside Africa can perform well in Africa under low-stress conditions. In observational trials for irrigated lowland rice, Asian and African varieties performed equally well under low-stress irrigated conditions (a quarter of the varieties of both types were acceptable at all 10 locations). However, under the higher-stress conditions existing in upland areas, 25"1. of the African selections had overall acceptability while only 8"1. of the Asian varieties were acceptable. As additional reports become available, particularly from areas with more adverse environments, even greater differences should ap­ pear between introductions and locally developed materials. Exposing a wide range of varietal material to the highly variable conditions existing in Africa, as is done through IRTP-Africa, allows scientists to determine how varieties perform in dif­ ferent ecologies. IRTP-Africa assisted scientists in viewing trials at numerous locations during 1986 by supporting monitoring tours to Cameroon, Ghana, Ivory Coast, Liberia, Nigeria, Senegal, Sierra Leona, Tanzania and Malagasy Republic. 78 Two IITA scientists stationed in Cameroon provide technical support to the country's Na­ tional Cereals Research and Extension (NCRE) Project. The main objectives of the NCRE Pro­ ject are to provide rice varieties that are adapted to the various ecologies found in the country and to identify agronomic constraints and develop management practices to overcome these constraints. Varietal-improvement research in Cameroon during the past few years has led to the identification of a number of improved lines for the various ecologies found in the country. The performance of ITA 222, ITA 212, IR 3273-339-2-5, ITA 306 and CISADANE in 1986 was superior. In the cold-prone areas of Ndop, IR 7167-33-2-3, B 2161 C-MR-57-1-3 and RNR 29692 showed high and stable yields and were free from sheath rot and grain discoloration. IR 7167-33-2-3 has been released by the development authority of that area for general cultivation. For the northern region of Cameroon, ITA 222, ITA 306 and IR 3273-339-2-5 have given high and stable yields. These lines are now being tested in pilot projects before being extended to larger areas. Apart from the large irrigated rice-development projects in Cameroon, rice is also cultivated by small farmers using traditional practices. Four lines identified are now being tested in on­ farm trials managed by researchers and farmers. In one particular area, more than 2000 kg of improved seed have already been distributed to farmers. Agronomic research at Cameroon has shown that in the irrigated areas of the West and North West provinces, time of planting has an effect on the quality and quantity of grain pro­ duced. The optimum time of planting in North West Province depended upon the genotype. Land preparation was also an important factor affecting yields in Cameroon's Mbo Plain. Tillage methods leading to closure of soil pores increased water retention and prevented the loss of nitrogen. For these soils, traditional practices of preparing land by hoeing did not produce encouraging results. For the lowlands and uplands, application of prunings from the leguminous Crota/aria caricia considerably increased rice yields. The common problem of yield decline in upland soils of Mbo Plain was corrected by this low-input technology. Among the legume species tested, Cro/ataria caricia was the fastest-growing and was more easily cultivated than other species tested. Of the ways for increasing rice yields in West and Central Africa, the introduction of higher­ yielding varieties generally has been the most effective. However, in the widely diverse ecologies found in Africa, the many biological and physical constraints often nullify the benefits that can be obtained from high-yielding varieties. Research activities at IITA, as noted in this summary, are centering on overcoming these constraints, particularly through breeding for resistance or tolerance. Additional information on research activities referred to in this summary is available in the Annual Report of the Rice Research Program. 79 lITA Elite Rice Varieties Recommended to Nigerian Farmers Seed of two liTA varieties recommended 10 Nigerian farmers was presented to the director of the National Seed Service, who accepted the seed on behllU of the Federal Military Government Three lITA lowland rice varieties have been Table 2S. Characteristics of three supuior lowland rke recommended by the National Cereals varielits . Research Institute (NCRl) for cultivation by Grain yield, Amylose Cooking farmers in Nigeria. After over three years of Variety t/ ha cOnlenl , 070 lime, min . testing at sites located throughout the coun­ try, varieties ITA 212, ITA 222 and ITA 306 ITA 212 4.0-7.5 27 17 were noted as possessing superior qualities ITA 222 4.5-7.0 28 19 ITA 306 4.0-6.5 27 18 and superior yielding ability over varieties currently being cultivated in the country. Under moderate levels of management , In addition to the three lowland varieties, these varieties produced yields of 4 t/ ha, and the NCR I also recommended upland variely with good management practices, primarily ITA 128 to rice growers in Nigeria. ITA 128 the application of sufficient fertilizer , yields is a medium-height (130 em), blast-resistant of 6.5-7 .5 tlha can be obtai ned (Table 25). varielY with excellent grain quali ty . Several Because these varieties are relatively short­ other lIT A upland variet ies are performing statu red and stiff-strawed, they do not well in Nigeria and will soon be recommend­ lodge . In addition, they have high tillering ed for release to farmers. ITA 235 and IT A abil ity and are responsive to fenilizer. These 257 a re two of the top performers in trials characteristics make yields of over 8 t/ ha conducted over Ihe past two years. These possi ble under optimum conditions. drought-tolerant, blast-resistant lines are 80 gIVIng stable yields of 2.5-3.5 IIha under varied conditions. The lIT A elite varieties are popular in other African countries as well. In Cameroon, ITA 222 and ITA 212 are rapidly becoming the most widely grown varieties in the prime lowland rice areas. The same is true in Senegal, Mali and Ghana, where ITA 212 is giving the highest yields among all varieties grown. 81 Reducing Toxicity of Iron to Rice Plants Production of rice in areas where water is of potassium reduce the plants' tolerance to abundant throughout most of the year is iron . Attempts to correct potassium defi­ often limited by toxicity of iron to the rice ciencies by applying potassium chloride plants . Until recently, varietal improvement (KCI), a common fertilizer in Africa, only was considered the only practical way of aggravated the problem of iron toxicity combatting iron toxicity problems in Africa. because the chloride contained in the fer­ Other methods such as lime application tilizer is detrimental to the roots of rice (about 10 t/ ha) and drying the soil before plants and inhibits the enzymatic oxidation cultivation are generally too expensive or of ferrous iron, the form of iron toxic to the difficu lt for African farmers. plants . \ITA, however, has been investigating A trial conducted at Bende, Nigeria , in alternative methods for solvi ng the iron tox­ 1986, however, showed that supplying icity problem, which is a problem caused not potassi um by applying potassium sulfate on ly by high levels of iron, but also by (K1S04 ) to the soi l corrected the potassium nutrient deficiencies that limit the ability of deficiency, which led to lower levels of iron the plant to tolerate iron . \ITA scientists in the plants and to decreased iron toxicity have determined that in Nigeria, deficiencies symptoms (Table 26). The use of ITA 249 (a Appl}'ing potassium chloride (Kel) to iron toxic soils aggravates the iron toxicity problem (right); applying potassium sulfate (ISS04)' however, alleviates the problem (center) . 82 Table 26. Effect of potassium on toxicit)' rating and on iron content of rice plants. Fe content Treatment l Toxicity ratini of plant, ppm ITA 212 Control 7.3 2910 K,SO, 4.3 1390 ITA 249 ContmJ 5.0 1390 K,SO, 2.0 780 I Control: 25 kg Nand 25 kg P205 applied per hectare. K;.S04: same as control, plus lSS04 applied at rate of 125 kg K,0/h •. 21 = growth normal; 9 = all plants dead or dying. tolerant variety) in combination with potassium sulfate application further reduced the iron toxicity problem. The use of improved varieties along with improved soil management could enable rice production to be expanded to land that is presently too iron-toxic for growing rice. 83 Oryza glaberrima as a Source of Resistance to Rice Yellow Mottle Virus The destructive nature of rice yellow mottle and have identified O. glaberrima accessions virus disease (RYMV) makes the cultivation TOg 5674 and TOg 5681 as having high of susceptible rice in the wetlands of Africa levels of resistance to the virus . potentially risky. Therefore, breeding for O. glaberrima is a cultivated rice species resistance has been one of the objectives of indigenous to tropical West Africa. There the Rice Research Program of IITA. are other species indigenous to Africa, but Breeding focuses on combining resistance to they are not cultivated. Because of low yield RYMV with other desirable traits needed in potential and other undesirable traits, O. developing improved and high-yielding glaberrima is rapidly being replaced by varieties. Through crossing and intercross­ sativa or Asian rice varieties; there are only a ing, the R YMV resistance of several upland few areas in Africa where glaberrima is still varieties is being transferred into improved being grown. Al though glaberrima lacks the breeding materials. In order to diversify the desirable characteristics needed in modern sources of resistance, program scientists rice varieties, the gene pool of the species have also been screening germ plasm not only may be useful as a source of specific traits of Oryza sativa but also of the related species needed in breeding for better sativa varieties. O. gJaberrima O. sativa · The high level or RYMV resistance or the O. glaberrima accessions on the lert contrasts sharply with the susceptibility or the O. sativa varieties on the right. Through a backcrossing program, the resistance oro. glaberrima is being incor­ porated into O. sativa varieties having good agronomic characlerisUcs. 84 To transfer the resistance of TOg 5674 and resistant plants to be used for another cycle TOg 5681 into sativa varieties, a backcross­ of backcrossing were identified. Some ing program using IITA-developed elite amount of fertility has been restored in the lowland varieties ITA 212, ITA 222, ITA hybrids with the first backcross, and the 304 and ITA 306 was initiated. The objective plants also showed some improvement in is to produce progenies in which the agronomic traits over the glaberrima resistance of g/aberrima to RYMV is com­ parents, indicating that the prospects are bined with the good agronomic good that resistance to RYMV in glaberrima characteristics of the elite varieties. can be put into improved sativa varieties. It The F, plants from the initial crosses were will be interesting, too, to see whether male-sterile and were used as female parents resistance from the gfaberrima varieties is for backcrossing to saliva. The backcross the same as that in the sativa varieties CUf­ plants were raised and were then tested for rently being used in the breeding program. It resistance to R YMV using artificial inocula· is possible that combining resistance frpm tion. Based on visual symptoms as well as on the two sources will further enhance RYMV serological tests, including the Enzyme· resistance in a variety. linked Immunosorbent Assay (ELISA), the 85 Rice Lines Resistant to Pink Stem Borer Identified The breeding of varieties that are resistant to insect pests is one of the strategies used by liT A to achieve control of insects . In the last few years, sources of resistance to Africa­ specific pests such as the stalk-eyed fly and gall midge have been identified at liT A and have been used as sources of resistance in liTA 's rice-breeding program. Screening activities for one lepidopterous borer-the pink stem borer (Sesamia calamis tis Hamps.)-have al so been somewhat fruitful. During 1984-85, 650 rice varieties/lines from IITA, IRRI, WARDA, CIAT and IRAT and from national pro­ grams in Africa and Asia were evaluated for their resistance to the borer. Two of the en­ tries screened-IR 12631-38-2-1 and TOx 936-155-5-1-2-I-had lower levels of infesta­ tion than a commonly grown local variety, OS-6 (Table 27). Later, it was found that larval growth was inhibited and the development of "deadhearts" (damage to stem tissue caused by borer larvae) was delayed in these two en­ IR 12631-38-2-1, an entry identified as showing tries (Table 27). The lower infestation levels, resistance to tbe pink stem borer. is virtually frtt of the coupled with the inhibited larval growth and infestation symptoms exhibiled by the susceptible 05-6. the longer deadhearts-development period, provided a degree of resistance to the pink stem borer that can be used in the breeding yield loss while precluding any need for ex­ program. pensive and environmentally disruptive in­ Screening of additional lines is continuing, secticides. with the aim of locating more sources with possibly even higher levels of resistance. In­ corporating insect resistance in new varieties is of paramount importance, as varietal resistance is a natural means of preventing Table 27. Results of screening trials for entries showing resistance to pink stem borer. Infestation Days to developmenl Variety/ line Source level, 010 of deadhearts IR 12631-38-2-1 IRRI t3 .4 24 TOx 936-155-5-1-2-1 IITA 16.8 24 OS-6 (local) Zaire 62.0 19 86 Silica and Magnesium Application Reduces Grain Discoloration in Upland Rice Upland rice grown in the humid tropics in undesirable brownish color to the milled West Africa is prone to attack by diseases rice. and insects, which leads to lower grain In Onne, Nigeria, where IITA's high­ yields. Grain discoloration is a particularly rainfall station is located, grain discolora­ serious problem because it reduces not only tion is an endemic problem. The soils at grain yield, but also grain quality. Onne are highly leached and acidic, and only Severely infected grains are nearly black in limited amounts of nitrogen, potassium, color. with the discoloration even silica and magnesium are available to rice penetrating the starchy endosperm of the plants. Studies have shown that deficiencies seed. During milling, such grains break more of silica and magnesium increase the in­ readily and have a brownish color, which cidence of grain discoloration (Table 28). drastically reduces marketability. Where A field study conducted in 1986 showed parboiling is practiced, even a fairly low in­ that the grain discoloration problem can be cidence of discolored grains gives an reduced through applications of silica and magnesium (Table 29). The yield of the Table 28. Effect of nutrition on the incidence of grain silica-and-magnesium treatment was 340)'0 discoloration.1 greater than that of the control. Increases in two yield components-percentage of filled Nutrients supplied Grain discoloration ratini spikelets and IOOO-grain weight-and a lesser degree of panicle damage from insects N, P, K, Ca, Mg, Si 4.0 and diseases were associated with the in­ AlI but N 4.2 creased yield. All but P 7.5 All but K The grain discoloration index-a measure 4.4 All but Ca 6.2 not only of the number of grains that are All but Mg 9.0 discolored, but also of how discolored the All but Si 8.0 grains are-was lower for the treatments than for the control (Table 29), indicating I Values are means for five varieties. 20 = O-lOOJ~ di~colored spikelets; 9 = 91-100lli'() that there was less grain discoloration with discolored spikelets. the treatments. Table 29. Effect of silica and magnesium on the performance of rice at Onne I. Treatment Character Control Silica Silica and magnesium Grain weight, g/m2 234 248 314* ~o filled spikelets 62.0 70.8* 74.0- WOO-grain weight, g 25.6 26.7- 27.5- Score for panicle damage by insects and disease~ 7.6 5.'''' 4.8- Grain discoloration index3 65.9 42.6· 42.4- I Values are means for three varieties. 20 = no damage; 9 = complete damage. 30 = all grains free from discoloration: 100 = all grains completely discolored . • Significantly di fferent from the control. 87 The Effectiveness of Flash Tapes in Protecting Rice Fields from Grain-eating Birds In a recent survey , rice scientists rated grain­ eating birds as the most damaging pest of rice in Central and West Africa. Although much effort has been devoted to the bird problem, there is st ill no single solution , and farmers are obliged to physically guard their ripening crop during daylight hours. A recent innovatio n for keeping birds out of rice fields is flash tapes. These long , thin, shiny tapes reflect light, and they appear to flash as they are moved by air currents. The tapes come in several metallic colors and resemble in size and texture the magnet ic tape used in cassette recorders. In 1985, flash tapes were installed in all of IITA' s rice fields as the crops approached the time of flowering . The tapes were strung Flash tapes used in protecting rice fields rrom grain­ on poles so as to be suspended just above the eating birds . rice plants. During the first 7-10 days, the tapes were highly effective in scaring birds away. However, as the birds became ac­ allow one bird scarer to more effectively customed to the tapes and as the rice became handle a larger area, thus savi ng some cost more attractive with the forming grain, the of labor. However, the tapes will probably be birds again entered the fields, and after ineffective in protecting the rice crop in about a month, normal activity had been isolated fields where no other food source is resumed. It was observed, however. that available to the birds. while they were under the tapes, the birds, mainly weavers and bronze mannikins, ap­ peared to be nervous . During 1986, tapes were placed in selected fields, allowing the birds a choice between taped and untaped areas. In all cases, the birds avoided the taped fields. Similar trials conducted at Bida Agricultural Development Project (BADP) showed that under a choice situation, the birds avoided the taped fields. As a result, BADP has ordered a large quan­ tity of flash tapes to be sold to farmers. It appears that flash tapes can effectively pro­ tect specific fields from bird damage as long as the birds have access to food sources other than the taped fields. At IITA, where laborers are hired to scare birds from the fields, the fla sh tapes may 88 Annual Report Executive Summary Root and Tuber Improvement Program Root and tuber crops - cassava~ yams, sweet potatoes, and aroids, - are basic staples for millions of people in the humid and subhumid tropics. Cassava is very important in IITA's research mandate and received top priority followed by yams, sweet potatoes and cocoyams. Scientists continued with research aimed at: • improving root and tuber crop breeding lines and families to gain high and stable yields with resistance to major pests and diseases and acceptability to consumers. • implementing a biological control program to control the cassava mealybug and cassava green mites. • providing strong support to national root and tuber programs and cooperating closely with them in testing improved varieties and technologies and • providing training for national scientific and extension workers. Crop improvement technologies draw on the expertise of many scientific disciplines and in­ volve close cooperation by scientists in plant breeding, plant pathology, entomology, nematology, virology, biochemistry, food technology, plant physiology, and tissue culture. New technologies are developed and tested at farm level in close cooperation with other pro­ grams. The Virology Unit conducts studies on virus diseases of root and tuber crops and in­ dexes tissue culture stocks for international distribution. UTA also cooperates with its sister center, Centro Internacional de Agricultura Tropical (CIAT), through the mutual exchange of cassava germplasm for breeding purposes. In the con­ tinual search for sources of resistance to cassava mealybug (CM) and cassava green mites (COM), lIT A has introduced from CIAT seeds of different cultivars that have characters such as pubescence which are important in developing resistance to these pests. CIAT has been pro­ vided with high-yielding cassava clones (TMS 30001 and TMS 30572) that are resistant to cassava mosaic virus (CMV) and cassava bacterial blight (CBB); these materials have been con­ firmed to be virus-free by the Scottish Crop Research Institute, UK. [nternational testing of improved and selected lines continued in cooperation with national programs. Improved genetic materials were evaluated under diverse environmental conditions including locations in Zaire with Programme National du Manioc (PRONAM), in Cameroo'n with Cameroon National Root Crop Improvement Program (CNRCIP), and in Rwanda with Rwandan National Root Crop Improvement Program (RNRCIP). The Programme National du Manioc continued to improve plant varieties and farm techno­ logy make them available to farmers and strengthen the national program with in-service and degree-related training. PRONAM conducted variety trials and extensive multiplication and distribution of improved varieties in collaboration with other agencies. Some staff are undergo­ ing advanced training leading to M.Sc. and Ph.D. degrees. The Cameroon National Root Crops Improvement Program continued to develop suitable production systems for cassava, yams, sweet potato and cocoyams useful for low resource farms. Improved material was tested for yield, pest and disease resistance and adaptability in 89 zones with high to low altitudes and rainfall. Local production systems were evaluated to iden­ tify those most suitable for the introduction and adaptation of improved material. The Rwandan National Root Crops Improvement Program pursued its cassava and sweet potato improvement for the special problems of pronounced topographical relief and variable altitude and rainfall. Special attention was given during the year to the transfer of new technology to farmers. The program advanced through multilocational trials, in-service train­ ing and regional workshops. The Jamaica National Root Crop Improvement Program was active in accepting, evaluating and demonstrating lIT A proven systems and materials under local conditions. Improved lITA material was provided in tissue culture form for sweet potato and yam improvement. Twenty­ two varieties were introduced, maintained in the new tissue culture facility and multiplied for field evaluation and on-farm trials. The yam minisett technology was demonstrated and adapted to serve the export market and to provide disease- and nematode-free "clean" planting material. Training included staff participation in the training course on root crops research and production at UTA in lbadan, and a two-week training course for the Caribbean Basin par­ ticipants on tissue culture and minisett technologies. Tissue culture studies on microtuber formation in yam demonstrated that microtuber pro­ duction was more pronounced at higher levels of sucrose coupled with 12 and 16 hour daylengths, with tuberization occurring as early as one month after inoculation. Greater numbers of microtubers per plant were obtained when the plantlets were grown in semitransparent containers rather than clear plastic ones. Microtubers, shown to be disease-and virus-free, have great value in germplasm preservation and the international distribution of im­ proved planting materials. Further studies on the effects of the nitrogen-fixing bacterium, Azospirillium sp., demonstrated significant differences among sweet potato clones grown in vitro. In the presence of the bacterium, sweet potato plantlet growth was increased, decreased or not affected depen­ ding on variety. Such information indicates the possible role of Azospirillium in sweet potato production but much research needs to be done to maximize its potential. In the second year of a .mixed cropping study in a cassava-based farming system, the spiral, root-lesion, and root knot nematodes occurred in all plots. The root-lesion nematodes were the most numerous in the plot with the highest population on maize. The spiral nematode occurred in moderate numbers under maize and cowpea. Root-knot nematode numbers were at in­ nocuous levels in all treatments. The maintenance of nematode populations at relatively low levels suggests that the various crop rotations limit the increase of plant-parasitic nematodes and that multiple cropping is stabilizing nematode diversity and density. The screening of yellow cassava clones for high carotene content intensified during the year. Yellow cassava tuberous roots are nutritionally better than white tuberous roots due to the vitamin A precursor and they can be made into yellow gari without adding expensive palm oil. In the clones evaluated, the carotene content ranged from 30 to 420 microgram per 100 g fresh tuber and the content decreased in all clones as storage continued up to 28 weeks. Additional information on research activities referred to in this summary is available in the Annual Report of the Root and Tuber Improvement Program. 90 TMS 4(2) 1425 is the Outstanding Variety in 3-Year Cassava Trials Varietal trials on improved IlT A cassava agronomic characteristics: varieties were conducted over a three-year • The lowest average tuber cyanide content period (1983-86) at four locations -lbadan, at3.12mg/lOOg. Mokwa, Onne and Warri - in Nigeria. • A high average dry matter content of 32"To. These locations represent a wide range of • A relatively high resistance to cassava ecologies: Ibadan is in the transitional humid mosaic virus (CMV) and cassava bacterial forest zone with moderate rainfall; Mokwa blight (CBB) diseases. is in the Guinea zone; Onne and Warri are in • Moderate levels of resistance to the cassava the high rainfall zone with poor sandy soils. mealybug (CM) and cassava green mites No fertilizer was applied and the cyanide (COM). content of tubers was assessed by use of an • A high garification rate and very good automatic enzymatic assay method. The quality gari. results are summarized in Table 30. • Tubers are poundable - an important characteristic where consumers prefer TMS 4(2)1425 was the outstanding entry pounded cassava. in terms of agronomic characteristics over locations and years. The average yield The performance of TMS 4(2)1425) in recorded for this variety was 21 tlha, which these trials has a major implication for is twice that of the standard check variety varietal improvement in cassava. Up to now 60506 - formerly the variety recommended it was believed that cassava varieties that for best performance in Nigeria. The variety were low in cyanide content were also low­ also proved superior to all other entries in yielding and susceptible to pests. These relation to the following important results indicate, however, that it is possible to Table 30. Performance of five cassan varieties at four IMations over 3 years (1983-86) in Nigeria. Indicated Varieties factor 60506(Control) TMS 4(2)1425 TMS 30001 TMS 30572 TMS 50395 Yield, tlha 9.9 20.9 13.2 14.4 19.1 Dry matter. 117~ 26.8 32.3 29.0 31.5 26.3 Cyanide, mg/lOOg 4.5 3.1 4.0 5.0 8.1 Resistance to:· CMY 2.9 2.0 1.6 1.9 1.9 CBB 2.7 1.9 1.7 1.7 1.8 CM 2.8 1.0 3.3 2.3 CO\1 4.0 2.3 4.0 3.3 3.0 Garification rate, D,l'o 19 24 20 20 19 Gari quality·· 0 YO YO YO 0 Poundable No Yes Yes No No eMV, cassava mosaic virus; CBB, cassava bacterial blight; eM, cassava mealybug; COM, cassava green mites. Rated I to 5; 1 = no damage, 5 = severe damage. eM was rated in February 1987 when field infestation was uniform U Gari quality ratings were VG = very good; G = good. 91 improve cassava for bOlh high yield and low some important characteristics . TMS 30001 cyanide while also retaining resistance to the has been good as a low cyanide variety but is major pesls and diseases in Africa . The susceptible to CM and COM as well as root variety TMS 30572 has become very popular rot. Like many other varieties of cassava, among farmers in Nigeria because of its however, TMS 4(2)1425 is a favorite food of many desirable characleristics. grasshoppers which are periodic, but impor­ The resuils presented here indicale that t3m, pests of cassava especially in Western TMS 4(2)1425 is superior to TMS 30572 for Nigeria. A good harvesl of TMS 4(2) 1425 - the vllriety thai performed besl in three-year cassava trials. 92 Casssava-Groundnut Intercropping has Potential to Improve the Nutritional Quality of the Diet in Zaire Farmers in Central Africa face a continuous The storage root yield of cassava inter­ struggle to maintain the productivity and cropped with groundnut was higher when fertility of poor soils. The intercropping of groundnut was sown at a low plant popula­ crops such as cassava (Manihot escu/enta, tion (0040 x 0.20 m) than at a higher plant Crantz) and groundnut (Arachis hypogea) population (0.20 x 0.20 m), irrespective of offers many advantages in terms of soil fer­ the cassava planting pattern. This is due to tility, overall crop yields and the quality of high plant-to-plant competition in the food for human nutrition. Groundnut is a groundnut sown at 0.20 x 0.20 m. It seems relatively high protein crop which fixes that when the population that gives optimum nitrogen, reduces soil erosion and can con­ leaf area index (LA!) is exceeded, yield trol population levels of serious soil pests automatically drops because of excessive such as nematodes . Moreover, ground nut mutual shading of leaves leading to a reduc· contains amino acids that can reduce the tion in net assimilation rate (NAR) . The cyanide problems common among people population attained through the 0.20 x 0.20 who rely on cassava as a basic staple food. m spacing was probably beyond the op­ Zaire is one of the largest cassava-consuming timum in the system involved in this study. countries in sub-Saharan Africa and The yield components of ground nut were cassava-groundnut intercropping is one of not significantly affected by the planting the most important components of tradi­ patterns of cassava (Table 32). That is tional mixed cropping systems in the because cassava started competing for en­ Southwestern region of the country. vironmental resources quite late during the Ex)::criments were conducted to assess growing season when groundnut was being cassava-groundnut intercropping and to harvested. Therefore, the relative time of determine the effects of planting patterns on planting of both groundnut and cassava is the performance and yields of both crops. important. It appears that cassava does not Results show that cassava grown as a sole impose much competition at the beginning crop produced more and bigger storage roots of its growth cycle, but it does not tolerate than when intercropped with groundnut much competition either. (Table 31). This is the result of competition Analysis of competition between cassava for resources between cassava and ground­ and groundnut revealed that groundnut was nut at the early stages of growth. the dominant crop where double-row ;y .... ,.' A~: ''--l-:~';;' -- .:::.i - .'C" ~\,.~~~~~,~ ~c~c~. ,:%,,·.'1;~~\ '-n-. '.?, -- '\.:(~ ...\. ;;: - '- ... -,. -~, ... ~, ':0 _~ __ ~:j _~ .......... ':,.. ' .. ...~ _..:... ..- ~~v:. .. ;> . -.:" " ...... ~ ."""' , .... ~ "~,,-_ ,'\' --,,\-~, -~~---::-l>o. ~';::- - ': .. '":',..-. ... )~: IiilIl -:> ':/.. .;,.~~ '';~;(.-'' ~}~,., :}li(;' ". ,'~ ~>t~lc:; .' {-'t:" ..'. . \f.~-'' ,-,_,-'._- .,.'.I.c "_"i-r J.... .,..,. ~~ ......~ ; .-....... . :~ ~;, , .. ,.~... . _~_ ':"" "., ,--,t«,-._. . J• . . ~ 1 ~ • -, •. ~ .' ../" " .~~:"",.. ri' \c~;" i~\¥"t / 1' ~~\ ,,·:~SS~: · . > " . -#f~:",' '~.,;.,.,...~. ". ... ~':I:)._ :"{,_ /. " .. :,....o "--'I._.: ;;C ""'_' III Cassava intercropped with ground nut. Research in Zaire indicates that this crop combinaHon gives a high protein yield per hectare and can contribute signi ficantly toward improving the nut ri tional value of th e diet in the Southwestern region of the country. 93 Table 31. Fresh storage root yield of cassan grown alone and intercropped with groundnut in different planting patterns. Treatment combinations Yield (tfha) Year I Year 2 Mean Sole cassava in DR 18.2 15.8 17.0 Sole cassava in SR 17.6 14.6 16.1 Cassava DR + groundnut (0.20 x 0.20 m) 13.0 13.2 13 .1 Cassava DR + groundnut (0.40 x 0.20 m) 16.1 13.3 14.7 Cassava SR + groundnut (O.40xO,20m) 12.9 10.4 11.6 Cassava SR + groundnut (O.4OxO,20m) 15.6 12.5 14.0 LSD (0.05) 5.0 2.0 DR = Double rows SR = Single rows Table 32. Grain yield of sole groundnut at two plant populations and with cassan in different planting patterns. Treatment combinations Grain yield (kg/ha) Year I Year 2 Mean Sole groundnut at 0.20 x 0.20 m 1,690 1,040 1,365 Sole groundnut at 0.40 x 0.20 m 1,730 1.090 1,410 Cassava DR + groundnut (0.20 x 0.20 m) 1,330 875 1,102 Cassava DR + groundnut (0.40 x 0.20 m) 1,710 1,005 1,357 Cassava SR + groundnut (0,20 x 0.20 m) 1,410 835 1,122 Cassava SR + groundnut (0.40 x 0.20 m) 1,570 1,035 1,302 LSD (0.05) 250 175 Table 33. Protein equivalent of cassava and groundnut as affeded by planting patterns and crop combinations over two years. Protein equivalents (kg/ha) Crop combination Cassava· Groundnut Total Sole Cassava DR 153,0 153.0 Sole Cassava SR 144.9 144.9 Sole Groundnut (0.20 x 0.20 m) 663.9 663.9 Sole Groundnut (0.40 x 0.20 m) 690.9 690.9 Cassava DR + groundnut (0.20 x 0.20 m) 105.3 539.9 645.2 Cassava DR + groundnut (0.40 x 0,20 m) 131.4 652.7 784.1 Cassava SR + groundnut (0.20 x 0.20 m) 103.5 549.8 653.3 Cassava SR + groundnut (0.40 x 0.20 m) 126.0 639.4 765.4 • Means of two cultivars Protein equivalents: Cassava: 0.43/l00 lb DR = Double rows Groundnut: 22.54/100 lb SR = Single rows 94 cassava was intercropped with groundnut at The following are the major conclusions both the 0.20 x 0.20 m and the 0.40 x 0.20 m of this study: plant populations. It seems that the com­ • An intercrop of cassava planted in double petitive ability of cassava depends largely on rows with groundnut at a plant population its planting arrangement and plant popula­ of 0.40 x 0.20 m resulted in the highest tion. yields of cassava and groundnut. The protein equivalent of cassava and However, cassava planted in single rows groundnut were higher in the intercropping and intercropped with groundnut does systems as compared to those of sale cassava not lead to excessive yield reduction of and sole groundnut (Table 33). The high groundnut. protein percentage of ground nut and the • The high protein yield per hectare from high yield potential of cassava probably intercropped cassava and groundnut in­ accounted for the increase in protein yield dicates that this cropping system can per hectare from intercropping. contribute significantly toward improv· ing the nutritional value of the diet in Southwestern Zaire. 95 Elite Cassava Clones Assessed for Gari Quality Can for sale on a roadside market in Southwestern Nigeria. UTA elile varieties of cassava have become very popular with farmers in Ihis region . Gari is a traditional and popular food made Analysis of variance showed that there are from cassava in West Africa . Over the years significant differences among varieties in farmer and consumers have developed relation to garification rate, fiber content preferences for certain cassava varieties and in the swelling capacity of gari. The dif­ based on color , garification rate (g of ferent cassava clones can be arranged in gari / lOOg fresh peeled tuber) , and swelling decreasing order of garific31ion rate , swell­ capacity. ing capacity and fiber content of gari (Table To determine varietal differences in re­ 34). la tion to gari quality, UTA prepared gari Higher gari yields are obtained from fro m 14 elite cassava clones during the first clones with high garification rate . The first season (May) in 1984, 1985 and 1986. The six clones in the table have garification rates amount of gari produced from a 10 kg fresh of 20"70 or more with TMS 4(2)1425 yielding peeled tuber was recorded for each cione . Dry 24%. Good quality gari should swell to at matter, He N, total soluble sugars, fiber and least three times it s dry volume when soaked protein contents, and the pH of the different in water. Only three of the clones produced gari samples were analyzed. Physical proper­ gari with a swelling capacity of less than 3.0 . ties such as swelling capacity in cold water, The swelling capacity values ranged from 2.7 gel consistency in water and in KOH, gari to 4.6 times the dry volume . The less fibrou s color, relative eba (paste product of gari) the gari is, the better its quality. Fiber con­ texture, and amyiograph consistency were tent ranged from 2.6 to 5.0% with the last also determined. seven clones having a value of 3.0% or less. 96 Table 34. Cassava clones ranked for gari quality Among the six clones with high garifica­ (garification rate, swelling capacity, and fiber content). tion rates, only TMS 4(2) 0267 swelled less Garification Swelling Fiber than three times its original valume, and rate] capacit:r content2 only TMS 63397 had fiber content greater than 3.0'\10. Thus, TMS 4(2) 1425, TMS TMS 4(2) 1425 TMS 30337 TMS 30337 60142, TMS 42025, TMS 30555 and TMS TMS 60142 TMS 40081 TMS 30211 TMS 42025 TMS 42025 TMS 50395 30572 produce gari of a quality that will TMS 30555 TMS 50207 TMS 50207 satisfy both farmers and consumers. TMS 4(2) 0267 TMS 60142 TMS 3()()()1 TMS 63397 TMS 4(2)1425 TMS 40081 TMS 30572 TMS 50395 TMS 63397 TMS 50395 TMS 63397 TMS 42025 TMS 30001 TMS 30572 TMS 30572 TMS 50207 TMS 30001 TMS 60506 TMS 60506 TMS 30555 TMS 4(2) 0267 TMS 4()()81 TMS 605iJ6 TMS 30555 TMS 30337 TMS 30211 TMS 4(2) 1425 TMS 30211 T:v1S 4(2) 0267 TMS 60142 1A verage for 3 years 2Average for 2 years 97 Cassava Chips Offer Real Potential for Utilization in Africa Fried chips made from cassava flour have making and frying process and made into been a popular food for years in countries chips (Figure 12). Initial experiments with such as Indonesia, Malaysia, Philippines, cassava chips at liT A showed that the qual­ and India. The utilization of major staple ity of chips varied with on the type of root and tuber crops such as cassava is cassava flour used . A study of the factors af­ receiving increased attention in Africa and fecting chip quality was conducted in 1986. greater efforts are being made to find new The process through which cassava ch ips and acceptable food products from these are made involves making a dough from crops. Cassava chips are a product that have cassava flour using salt and water and then much potential in Africa. steaming the dough before cutting it into Cassava chips can be made from tubers or thin chips which are dried and then deep-fat from cassava flour. Varieties that have a low fried. Chip quality depended on the total cyanide content are used to make chips from soluble sugar (TSS) concentration and on tubers. Many varieties however. have some paste viscosity characteristics of the medium cyanide content that can be reduced flour. The color of chips, before and after if cassava flour is put through a dough- frying, varied depending on the variety from Dried and fried cassava chips from nour of four dirre-renl varielies. The color of dried and fried chips varied wilh variety. 98 HeN concenlrolion which the flour was made. The variety TMS 10.0 I 4(2)1425 gave the lightest colored chips followed by TMS 30572, TMS 30555 and • TMS """" TMS 50395 which had the darkest color. As 8.0 • TMS30S12 TSS content increased, the color of chips 1MS 4(2)142S darkened . This was due to the formation of browning substances between the free sugar and amino acids which contributed to the 6.0 bitter taste of the dark chips (r = 0.7994, P = O.OOI)(Figure 13). There was no correlation between taste and total HeN levels when flour from low­ 4.0 cyanide cassava varieties were used. If the starch in the flour gelatinizes and there is less starch retrogradation during the cooling of dough , chips expand more during frying. 2.0 Therefore, to process good quality chips from cassava flour , the flour should be from medium to low cyanide varieties that have low TSS concentration, high maximum paste 0.0 Fresh Flour Sleomed Cr ied Fried viscosity and setback viscosities. luber dough chips chips Cassava chips have two major advantages Figure 12. Tolal HeN concenlralion in rresh luber. which are important in relation to food flour, steamed dough, dried and rried chips or cassava utilization and human nutrition in Africa. varielies TMS 50395. TMS 30572. and TMS 4(2)1425. • The process of dough making allows the Color rating .------ 2... . 4.8 ••• • • •• • • 3.6 • y= S.08-0.2SX 2.4 • 2e• • 1.2 . . .. 0.61L-________~ L-----------~----------~----------~--------~ 0.0 3.c 6.4 9.6 12.8 16.0 Total soluble sugar concentration (%) Figure 13. Relalionship between color raring or chip and lolal soluble sugar concentralion (r = -0.6598. P = 0.0001). 99 quality and nutritive value of the product to be improved and enriched through the addition of high protein flour, flavoring or coloring substances . • The drying process, before frying of chips, makes it possible to store chips for relatively long periods (up to one year in sealed plastic bags) without the problems associated with chips after frying such as rancidity from oil and loss of crispiness - all of which usually occur within a relatively short period (2 - 3 weeks), 100 Prolonging Dormancy of Yam Tubers Through the Use of Gibberellic Acid (GA3) Postharvest application of Gibberellic Acid (GAJ ) has been shown to be effective in ex­ tending the length of the dormancy period in some cultivars of Dioscorea alala. Dioscorea rotundato, Diosco rea esculenta and Dioscorea trifida. It has also been shown that GAJ can be applied to sprouting tubers to reinduce dormancy. A trial was conducted to assess the effect of GA3 on two cultivars of Dioscorea rotun­ data. Tubers of the two cultivars, TDr 131 and TDr 179, were harvested when the vines had partially or completely senesced and were treated with GAJ within three days of harvest. Each sample consisted of 12 tubers of about the same size. The tubers were washed free of soil particles and then com­ pletely immersed in the appropriate treat­ ment solutio n for a specific length of time. There were two basic treatments; a lower concentration of GAJ (150 mg/ L) for a . WITH LOW CONe of GA3 longer time, and a higher concentration of < s GAJ (I gi L) for a shorter time. In the latter, more than one batch of tubers were treated in the same solution in succession. The con­ Profuse sprouting characterizes the culti var TDr 179 trol treatment involved tuber immersion in under Ihe control treatment (above) and (be/ow) a low concentration of GA:J extends the dormancy period for water over long and short periods of time. 14 weeks after application. After treatment, tubers were drained, dipped in Demosan (10 giL), air dried and placed in boxes on shelves in the yam barn where sprouting, weight loss and incidence of rot­ treated tubers of both cultivars were also ting were monitored weekly for approx­ healthier and lost much less weight during imately 20 weeks. storage than those in the control treatment. Results (Table 35) showed that GAJ con­ Four factors seem important in determin­ siderably extended the dormancy period of ing duration extension of dormancy. The both cultivars . During the first 14 weeks first is the concentration of GAJ used. For a after treatment, only negligible sprouting oc­ given batch of tubers, the greater the quanti­ curred on the tubers treated with GAJ . Dor­ ty of GAJ applied the greater the extension mancy extension was comparatively longer of dormancy. Second, different species of in TDr 179 than in TDr 131. In the control cu lti vars respond different ly to the treatment, TDr 179 achieved over 50"10 postharvest application of the same level of sprouting after 8 weeks whereas it took 18 GAJ . Third, the physical and physiological weeks for a comparable level of sprouting to conditions of the tubers at treatment are im­ develop on tubers treated with GAJ . The portant. GAJ treatment is most effective 101 Table 35. Effect of Gibberrellic Acid (G~) applied as Serelex on sprouting of yam tubers (illr 131 and TOr 179) during storage"'. 'rDr 131 Treatments Extent of sprouting 8 wks 12 wks 14 wks 16 wks 18 wks 20 wks I Water (22 hrs) 5 15 71 90 93 100 2 Water (1.5 hrs) 3 28 73 98 100 100 3 150 mg/L Berelex (22 hrs) 0 0 0 28 66 100 4 I giL Berelex (1.5 hrs) 0 5 7 30 79 100 TDr 179 Treatments Extent of sprouting 8 wks 12 wks 14 wks 16 wks 18 wks 20 wks I Water (22 hrs) 52 90 93 95 100 100 2 Water (2 hrs) 59 78 88 94 100 100 3 150 mg/L Berelex (22 hrs) 0 0 11 15 49 80 4 1 giL Berelex (2 hrs) 0 0 18 24 62 93 *Values represent percentages of tubers that sprouted and are means of 4 replicates. when applied immediately after harvest or before natural curing has occurred. Fourth, the longer the time of immersion, the greater the prolongation of dormancy. It should be noted that even relatively low concentrations of GAl give long extension of dormancy if tubers are immersed for about a day. Moreover, the same solution can be suc­ cessfully used repeatedly for different batches of tubers. Successful extension of dormancy ensures that the tubers remain healthy and of good quality during storage. This in turn will en­ sure that good market values can be obtain­ ed over a comparatively longer period. 102 A Production System for Medium-sized Seed Yams In West Africa, big ware yam tubers (3-7 kg) is considered late; earlier planting is likely to have been traditionally produced by produce bigger seed yams. farmers. To produce big tubers, however, In collaborative trials conducted at three farmers have to prepare big mounds or locations by IITA and Oyo North heaps, plant large sellS (500g to I kg) and use Agricultural Development Project at Shaki, big long stakes to support the big leaf Nigeria, seed yams weighing 70 - lOOg and canopies that develop from large sellS. These planted at a spacing of I m x I m produced requirements often become major produc­ tubers which weighed 1.64 kg (TOr (31) and tion constraints to yam growing. The pro­ 1.20 kg (TOr (79) . These sizes of yams are duction of medium sized (1 -2 kg) tubers within the medium-sized tuber range or could reduce production constraints because "table yams". While yams of this size range small heaps or mounds and smaller planting may not be acceptable for certain cultural setts would be adequate. The staking needs uses, they may well be acceptable to urban would be reduced, and plant populations consumers. Moreover, they would be prefer­ could be increased. The study reported here red for export markets and industrial pro­ shows that large quantities of planting cessing. materials of sizes adequate for the produc­ lion of medium sized ware yams can be pro­ duced in nursery beds. An experiment was conducted to evaluate the effect of various high plant populations (250,000 - 2million plants/ ha) of sprouted yam minisetts on the size of seed yams pro­ duced. The variety used was TOr 131 and different plant populations were obtained by planting sprouted minisetts at various spac­ ings. Detail on seed yam sizes and multiplica­ tion ratios from samples taken at 3 112, 4 112 and 5 112 months after planting (MAP) are also given in Table 36. The multiplica­ tion ratios increased at all sampling dates, suggesting that the minisetts were productive at all plant populations and total tuber yields, in all cases, exceeded the weight of tubers planted. The results reveal the capaci­ ty of the yam plant to withsdand very high plant populations . At a plant population of 250,000 per ha (20 cm x 20 cm), seed yam sizes were produc­ ed that were equivalent to what is produced '11 iH,\I' under normal field conditons with ridges. At the population level of 444,000 plants/ ha, seed yams that weighed close to 100 g were The capacity of the yam plant to withstand very high plant populations was demonstrated in an UTA experi­ obtained. A wide range of yam sizes were ment conducted in 1986. Above: lubers from a plant produced for the range of plant populations populallon of 2S0,OOO/ ha . Below: The luber sizes thai studied. The planting date i.e . June 24, 1986 result from a plant population of 2 miUion/ ha . 103 Table 36. Effects of high plant population on white yam(D. rOlundata) seed sizes and multiplication ratio of minisetts. Spacing Plant population Seed size Multiplication ratio (000 per hal 31/2$ 41/2 5 112 3 112 4112 5 112 20 em x 20 em 250 175.6 206.0 255.8 5.9 6.9 8.5 15 em x 15 em 444 94.5 92.8 109.9 3.2 3.1 3.7 2QemxlOem 500 71.9 72.8 163.9 2.4 2.4 5.5 lOemxlOcm 1,000 58.0 74.9 63.3 1.9 2.5 2.1 Drill in rows 20 em apart 1,030 55.5 58.3 44.6 1.6 2.0 1.5 Drill in rows 15 em apart 1,250 53.3 54.3 56.4 1.8 1.8 1.9 Drill in rows 10 em apart 2,000 42.1 40.8 36.6 1.4 1.4 1.2 LSD at 51110 15.2 77.6 113.6 0.7 2.6 3.8 'Months after planting (MAP). This experiment shows that the seed setts • Costs of production are low as the need for producing these medium sized yams for plastic mulch and staking is obviated; tubers can be readily produced in nursery there is less weeding due to the early and beds at high plant populations (444,000- complete closure of the canopy. 500,000 plants/hal. The major advantages • Harvesting is much easier as tubers are less of production systems based on relatively bulky and more readily packaged and high plant populations are: transported. • Large quantities of seed yams can be • Small tubers are more easily and effec­ produced from small land areas, tively stored. • Production is under the direct control of the farmer thus facilitating good management. 104 Realizing Maximum Tuber Yields of Yams (Dioscorea sp.) Grown from Minisetts In recent years much progress has been limited number of tubers that survive reported in relation to the development of postharvest storage from each clone, the high-yielding clones of yams and in the materials available from planting with breakthrough achieved in seed mUltiplica­ 200-250 g setts will suffice for less than three tion through minisetts. In 1986, trials were stands. conducted to: The findings from these trials indicate • determine if the growth stage of clones at that: selection influenced the mean and maxi­ • Clones can be adequately ranked for pro­ mum tuber yields for white yam (D. ductivity and yield using 50 g minisetts rotundata) and water yam (D.alata). thus obviating the need for heavier (200 g) • assess the suitability of clones in terms setts. of yield when planted as 200 g setts and • The maximum realized tuber yields from 50 g minisetts. minisetts planted under plastic mulch at The first trial was conducted with 50 g the spacing indicated is around 50 tlha. minisetts spaced at I x 0.5 m and planted on ridges under plastic mulch. The incidence of leaf diseases (necrosis and virus) was low. Table 38. Comparative yield rankings of eight Wilier yam clones, 1986. The stage at which clones were selected in­ fluenced the mean and the maximum tuber Tuber yield t/ha Comparative yield yields for white and water yams (Table 37). rankings· In the second yield trial, eight clones of D. TDa: 50 g sett a/ata were planted using 200 g setts and 50 g 200 g sett 50 g sett 200 g sett minisetts at similar spacings to trial one. The 301 22.52 23.60 1 3 ranking order of these clones did not change 316 22.48 32.30 2 1 significantly for the two sizes of sett (Table 291 22.28 28.20 3 2 38) and the use of minisetts facilitates more 297 22.00 20.60 4 5 67 18.34 21.70 5 replications in breeding trials. Given the 4 251 17.76 20.40 6 6 315 16.46 18.10 7 7 5 14.06 16.80 8 8 Table 37. Tuber yield of selected yam clones in trials using tuber minisetts. • Spearman's coefficient of rank correlation was fs = 0,905" Growth stage at Yield t/ha selection Mean Maximum Selected clones White lam (D. rotunda/a) Preliminary 16.6 48.0 89 Intermediate 17.6 27.8 32 Advanced 13.2 20.8 10 Uniform 10.7 15.7 12 Wain yam (D. %ta) Preliminary 36.0 48.8 II Uniform 20.0 31.8 II 105 Africa-Wide Biological Control Project A Strategy to Initiate and Develop National Biological Control Programs (NBCPs) in Africa The UTA Africa-wide Biological Control tional and regional levels as required using Project (ABCP) has had three major objec­ the ABCP as the basic model. tives since its establishment in 1980: In the first five years of the project the ( I) To achieve permanent. ecologically safe major thrust of research and development and economically viable control of cassava work has concentrated on the first objective mealybug (CM) and cassava green mites and considerable progress has been made (COM) in Africa through the establishment and reported. Advances in basic research in­ of a scientific and technological base for clude: the biology of CM and COM. ex­ classical biological control. ploration for natural enemies of these pests, (2) To initiate and develop biological con­ mass rearing and experimenral release trol programs at national levels (NBCP's) technologies for natural enemies. making ex­ principally through the training of support perimental releases and monitoring and specialists and technicians from African eval uating the impact on CM . Recent pro­ countries in biological and integrated pest gress in these areas is highlighted in the ar­ control disciplines . ticles that follow. (3) To assist in the development of Following progress on its first objective. capabilities in Africa to extend biological the ABCP is devoting greater efforts to the control to other crop pests and weeds at na- second major objective which centers on Scienlists and technicians from the nalional research program (PRONAM), Zaire who haye been Irtllined in biological control by UTA as part of the ABCP. 106 Figure 14. ABCP train­ ing to dale at degree and technician levels ror AJrican countries in the caSSBva bell. ~ _1l1IInI. . t_·84) ~='=I'23) moving out the technologies already have been developed at national levels, the developed to African countries. A strategy ABCP continues to act as a catalyst by pro­ to initiate NBCP's, and provide continuing moting biological control as an integral part support through to full-scale development of Integrated Pest Management (IPM) in and consolidation at national levels, has Africa. The ABCP will also maintain a com­ been put into effect for the first time. The munications network between national pro­ training of specialist personnel to advanced grams and key international institutions, levels (masters and doctorate degrees) and as thus underpinning biological control across highly skilled technicians is central to the the continent. development of national capabilities for In 1986, initiation packages were im­ biological control. To date, 23 trainees have plemented in 12 countries and donor support commenced training for advanced degrees has been obtained for the full-scale develop­ awarded by African and European univer­ ment of NBCPs in a further five countries sities and a further 84 have completed short­ (Figure 15). The future strategy will continue term training courses (4-6 weeks). See Figure to place major emphasis on training and on 14. NBCP development at national levels. In addition to personnel training, IITA Specifically the ABCP aims to: has also provided seed funding to enable pilot • Initiate NBCP's in the remaining 20 programs to be started at national levels. Up countries of the cassava belt. to US$40,OOO per year for a two year period • Help develop, in collaboration with the is available to fund the "start up" costs of Food and Agriculture Organisation (FAO) national programs and, depending on of the United Nations and donor agencies, results, individual countries are encouraged adequate national structures to support to seek donor funding for full-scale NBCPs. NBCP's. During the initial development phase, ABCP • Establish a comprehensive communica­ provides essential resources for NBCP's in­ tions network between NBCP's and cluding technical advice, biological control ABCP headquarters. agents and materials. Once basic capabilities • Promote biological control and integrated 107 Figure 15. The develop· ment of NBCPs to date in Africa. - == CNltrIa wifh whiCh teCP - - i_nitiation_ pockeo egl n en pest management as important applied science disciplines in African Universities and agricultural schools through the dissemination of information and the organization of study tours to ABCP headquarters. 108 The Impact of Cassava Green Mites on Cassava Yields Cassava green mites (COM) Mononyche/lus Yield losses due to COM were determined lanajoa (Bondar) sensu lalo (Acari: by measuring the difference in biomass bet­ Tetranychidae). are among the most serious ween mite-free and naturally infested pests of cassava, Man ihol esculentQ Crantz, cassava planted in April . July and October in Africa. These mites have spread to 27 1984. The mite-free plots were sprayed every countries in the cassava belt of the continent 10-14 days with Rogor (dimethoate) as re­ and threaten production in many areas. quired to eliminate COM populations . The Yield losses ranging from 13 to 80 "10. dry matter of leaves, stems and tubers were which result from direct damage through determined at one or two week intervals defoliation due to high mite densities, have throughout the growing season. Other ar­ been estimated for Africa. but detailed thropod pest species were insignificant while studies have never been done. COM are the incidence levels of plant pathogens were most ly fo und on the lower surface of you ng simila r fo r the mite-free and infested leaves where they feed by piercing individual treatments. leaf cell s with their stylet-like mouthparts Cassava biomass in all treatments increased and extracting cell fluids . Damage symptoms during the first wet season. declined during include chlo rotic spotting. shortened inter­ the dry season , and increased again once the nodes and st unted leaf growth. IITA scien the rains began (Figure 16). Although the dry tists conducted a study to measure the im­ matter phenologies of both treatments pact of CGM on biomass production in within a planting date were similar, signifi­ cassava. cant differences were found between all Severe defoliation characterizes caSSllva plants heavil}' infested with CGM. 109 Tuber dry mailer ( g x 1000) Figure 16. Phenology of dry mailer accumul­ ation in tubers of sprayed and unsprayed Sprayed Unsprayed cassava p lanted in 2.5 April, July and October o---~ . Dry season .--.. Apr 1984. p----<> ~---o July 2.0 'V---&;J 'Y-'Y Oct ~ : ... .0 , 'V' 1.5 I ~-\0.-.. . ..d,I ,~ / " 1.0 ~ f .-. ' , I P_ -.. 'tjI I. ,$7 " I , 0.5 "i~ .... '7 .. -," ,';' ,I /' ... ."....-;...,..- I ' I ~Jf-..if-!j. ". J F M A M J JASONDJFM A M J J A 1984 - 1985 treatments during the dry season with the ex­ quantified in Table 39. For the July planting ception of those planted in October (Table a 45"70 loss of tuber dry matter was observed 39) . This decline in biomass can be at one hundred days into the dry season. An in­ tributed to a combination of drought stress teraction between COM and planting date (as seen in the decline in dry matter in the was evident in the amount of biomass lost. difference in dry matter between The effect of COM on young plants with treatments). The October planting was too little accumulated biomass, and only close to the beginning of the dry season to moderate growth rates during the dry distinguish COM damage from drought season, was difficult to separate from stress. drought stress. The biomass of all plants increased once Older plants, with considerable biomass in the rains began but existing dry matter dif­ stems and tubers , suffer the greatest losses ferences between treatments were either under COM attack. Mite feeding effects the maintained or increased, even though COM leaves which normally provide for most of populations were virtually eliminated very the metabolic demands of the plant; conse­ early in the rainy season. These results in­ quently, when the leaves are damaged, the dicate that plants damaged by COM com­ plant is forced to metabolize biomass stored pensated for drought stress but did not in the stems and tubers to stay alive. Plants recover from losses due to mite damage. with the largest amount of living tissue had The impact of COM on cassava yield the greatest metabolic demand during the dry depended on the age and the part of the host season. The empirical evidence in Table 40 plant affected. The phenology of stem and shows that July plants consistently had the tuber biomass were similar and a trend of greatest COM-induced losses. This is ex­ continuous decline in dry matter content plained by the growth stage and associated emerged about two months into the dry physiology of plants during COM attack. season . The extent and pattern of losses July plants were at the optimal growth stage observed are indicated in Figure 16 and during the dry season and had the highest 110 Table 39. Mean dry mailer loss in grams (and OJo) due 10 CCM for leaves, siems and tubers at the end and 100 days after the dry season f!"Om three planting dates (comparisons made using t tests) . LEAVES STEMS TUBERS Planting end of IOOd y. afler end of lOOdy. afler end of lOOdy. afler Date dry season dry season dry season dry season dry season dry season April 57.7 (26.5)·· 34.0 (29.3)· 389.2 (23.6)·· 356.3 (16.6)· 153. 1 (10.5)· 529. 1 (24.5)·· July 48.9 (47.1)" 69.8 (50.3)·· 121.6 (30.8)· · 739.4 (49.6)·· 236.5 (32.9)·· 899.1 (45 .3)·· October 6.8 (23.1) 98.3 (46.4)·· 6.8 (11.4) 426.4 (48.9)·· 2.4 ( 9.3) 329.1 (41.4)·· ... P < .05 """p< .01 metabolism per gram of dry matter, thereby increasing their exposure to losses. The April plants had a high proportion of woody tissue while the October plants were still using their respiring plant parts at this stage. The presence of CGM throughout much of the cassava belt in Africa has been associated with a reduction in crop yields. For the first time, the results reported here provide information on yield losses directly attributable to CGM. These results show that the entire plant suffers from mite feeding and that the biomass lost to CGM is never recovered. The shortening of the internodes during dry season growth on stems of cassava plants infested with CGM . III Strategies for Classical Biological Control of Cassava Green Mites The great strength of biological control as a development of mass rearing capabi li ties pesl control strategy is that its effects are and relatively rapid and persist in a stable way • determining the field characteristics of once successfully implemented. In Africa to­ COM in order to release natural enemies day it is increasingly accepted as a very ap­ under most favorab le conditions fo r propriate technology for the control of establishment. economically important pests of cassava, Applied research is directed primarily since it requires neither special skills nor toward techniques that improve the efficien­ resource inputs from fa rmers. The goal of cy of activities related to control. Surveys of the Africa-wide Biological Control Project CGM and associated indigenous natural (ABCP) in relation to cassava green mites enemies in Africa are being conducted to (CGM) is to pursue a control stralegy based provide essential information for use in on biologically sound principles which in­ development of release and follow-up tegrate basic and applied research com­ strategies . The spread of CGM since 1971 is ponents. Basic research will add to the fun­ depicted in Figure 18. Several taxonomic damental knowledge of cassava pests and guides for identifying relevant pests and forms the basis for assessing and under­ beneficial species have been written; a standing the eventual outcome of the control "quick count " method for estimating mite effort. densities has been perfected and a sampling This research thrust is in two major areas: plan, based on density-specific procedures, has been developed. • measuring CGM 's biotic potentials under In South America, CGM populat ions are contro lled conditions important for the usually maintai ned under natural control by Righi. cassa\'B thai is rr~ from CGM altuck and (le/t) the plan I ddolialion (hal charuclerizessevere infestation. 112 Quarantine Mite behaviour Basic research Applied _rch Training Regional liaison Artificial diet BiotaxonomV Exploration Ento~thogens and prailminary screening for biological control candidates Countries requesting ABCP 888istance for controlling tCGMI. Figure .7. The nelwork of inlcrnalionalcollaboralion ror classica l biological conlro l or CGM. a combination of local predators and being selected based on a combination of weather I especially where the crop has been field and laboratory characteristics. locally selected and is cultivated in a tradi­ However, the final verdict on the effec­ tional manner. Mites of the family tiveness of any natural enemy can only be Phytoseii d are especially important determined in the field with experimental predators of CGM and have been selected as releases and follow-up evaluation . Five ex­ the primary agents for introduction against otic phytoseiid species have been brought to CGM in the initial phase of foreign explora­ llTA and are being maintained . Mass rear­ tion . These natural enemies have long been ing techniques for producing large numbers associated with CGM and other spider mites of phytoseiid predators are being in­ of the family Tetranychidae . Their potential vestigated for the planned large-scale as biological control agents is also well releases and for delivery to national documented . Phytoseiids are better at main­ biological control programs. taining mite pests at low population levels But biological control, like other research­ than most insect predators. dependent disciplines, must incorporate the A catalog of phytoseiids associated with results of many studies from different CGM in the Neotropics is being developed. specialized fields. In an effOrl to harness Promising candidates for introduction are available world expertise and resources most 113 Figure 18. Spread of cassava green mi te (CGM ) MOllollychellus tallajoa (Bondar) sensu laro in sub-Saharan Africa since its presence was first confi rmed near Kampala . Uganda in 1971 effective, important work on COM is being onomy of phytoseiids at the Empresa conducted either in collaboration with, or Brasileira de Pesquisa Agropecuaria, Brazil through contracts with, other institutes and (EMBRAPA); taxonomy of tetranychids at agencies (Figure 17). This includes foreign the University of Sao Paulo, Brazil; artificial exploration and preliminary screening of ex­ diets for transporting CGM natural enemies, otic natural enemies at CIAT in Cali, Col­ survey of entomopathogens of COM and ombia; international quarantine services at biotaxonomy of COM at the International the CAB Internati ona l, Institute of Centre of Insect Physiology and Ecology Biological Control, London (formerly (IClPE) , Nairobi, Kenya; and behavioral CIBC); simulation modeling of the cassava studies of exotic phytoseiids at the Uni versi­ ecosystem including the COM at the Univer­ ty of Leiden, the Netherlands. sity of California, Berkeley (UCB); tax- 114 Update on Release, Establishment, and Impact of Epidinocarsis lopezi and Other Natural Enemies of the Cassava Mealybug In 1986, releases and studies of the a large scale operation in five provinces in parasitoid Epidinocarsis /opezi (De Santis), the northern half of Zambia, with ferry introduced from South America into Africa flights of beneficials from Lagos via for biological control of the cassava Nairobi , eight aerial releases were combined mealybug, Phenacoccus manihoti Mat. Ferr. with five widely spaced ground releases in (CM) by IITA's Africa-wide Biological Con­ August-September. Over 100,000 parasites trol Project (ABCP), continued (See UTA and predators of five different species (E. Research Highlights 1984) and other insects lopezi, Allotropa sp ., Diomus sp., and two were established which might be beneficial in Hyperaspis sp.) were released with an controlling CM. average mortality of less than 200/0. In 1986, the establishment of E. /opeziwas In northern Malawi, CM damage was so monitored in existing release sites and new catastrophic that food aid had to be provid­ releases were also made (Figure 19 and Table ed to farmers. In 13 fields, which were 40). In April-Maya series of aerial releases situated more than I km from the first releases was completed in central Cote release site, CM densities average 550 CM d'lvoire, at a time when the disperal front of per tip (or 2.74 ± 0. 13 SE as expressed in log E. lopez; was in western Ghana. Descen­ N). A series of ground releases led to the dants of the released insects were recovered establishment of E. /opezi. after the rainy season thus proving the Recovery of E. /opezi was also recorded feas ibility of the aerial release technology . In from Gabon . Thus, in 1986, the establish- ---- Cassava bell _ eM distribution 11111 111 ~ lopez; d;s!,;bu!;oo • §.. lopezi recovered Figure 19. Distribution o g. of cassava mealybug lopezi released but not yet recovered (eM) lind the wasp E. ? Questionable distribution of eM lopez.i. which Is the most effective be n efldal yel introduced to control eM. II 5 ment of this wasp was confirmed for all Table 40. First year of release and establishment of countries where release sites were revisited. natural enemies. This widespread establishment of E. lopezi Country E. [opezi Allotropa Diomus demonstrates the extraordinary adaptability of this species to diverse ecological condi­ Senegal 1984· 1984 tions. Gambia 1984· 1984 For the first time, the parasitic wasp Guinea- Bissau 1984'" 1984 Allotropa sp. was recovered, albeit in very Sierra Leone 1985 1985 1985 low numbers, and only on the release sites. Cote d'Ivoire 1986a· 1986a· 1986 This wasp attacks first CM instars and, since Ghana 1984· 1984 E. lopezi almost exclusively attacks second Togo 1984· 1984 Benin and third ins tars, this new parasitoid oc­ -- Nigeria 1981· 1985'" 1981(-) cupies a different ecological niche. It is, Cameroon therefore, concluded that this wasp, if Gabon 1-9-86· 1986 established, could contribute to the Congo 1982· Zaire 1982· 1986 1983· biological control already achieved by E. Angola lopezi. Rwanda 1-9-85· 1985 The coccinellid beetle Diomus sp. has been Zambia 1984· 1986a 1986a released since 1981 (See llTA Research Malawi 1985· 1986* 1986 Highlights 1981 and 1982, where it was call­ • establishment, i.e. recovery in the dry season follow­ ed Scymnus). In 1986, for the first time, this ing the release. beetle proved to be firmly established .. no release made but establishment confirmed as a around Kinshasa. Its distribution is limited result of natural dispersal from neighbouring countries. to the area where it can persist on Manihot a = aerial release. dichotoma, a tree form of cassava on which CM populations do not drop as low as on normal cassava during the wet season. provinces of Zaire. However, its spread was Several more predators were also released. much slower in the Shaba province, the ad­ While other coccinellids were never joining Luapula valley of Zambia, in Rwan­ recovered beyond the first generation in the da, and in the dry conditions of Senegal. field, the hemerobiid Sympherobius Therefore, it seems that at high elevations maculipennis (See Research Highlights 1982) and under very dry conditions, the spread of where another species name was given) was E. lopezi is slower than in the lowland humid occasionally observed in Nigeria from fields tropics. with an exceptionally high CM population in The impact of a benecifial insect can be 1986. Thus E. lopezi at present remains the shown by various methods: only widely established exotic beneficial in­ • Long-term assessment of the population troduced against the CM. fluctuations of the host indicates how E. lopezi has spread at a spectacular rate efficient the released insect is. Com­ from release sites (See llTA Research parison can also be made with the pre­ Highlights 1983,1984). In 1986, a continued release situation. rapid spread "\las reported in Nigeria, Benin, • In exclusion experiments the development Togo, Ghana, Guinea-Bissau, Gambia, of the host is measured under experimental Zaire, and Congo. Between Nigeria and conditions with and without access of the Ghana the parasitoid now occupies all areas beneficial insect-The difference in host where CM occurs regularly, but it is not pre­ population densities between the two sent in the north where no recent eM out­ treatments is then attributed to beneficials. breaks have been reported. It has spread • A computer simulation model based on equally well in the Bas-Zaire and Bandundu weather data, parameters concerning plant 116 physiology, and life-table data of the main Similar reductions in CM popu lation have insect pests and beneficials. Such a model also been observed in several other coun­ describes the various interact ions in quan­ tries . titative terms and assesses the impact of • Experimental evidence of E. lopezi's effi· introduced beneficials . All three ap­ ciency at the moment is only available from proaches are being used in the ABCP . UTA. When the parasitoid was excl uded CM populations in Nigeria, five years from CM in the field either by gauze sleeves after E. Lopezi's frrst establishment (See lITA (See liT A Research Highlights 1984) or by Research Highlights 1984), continue to be insecticide sprays, eM densities were much low, with a mean for farmers' varieties that higher than in the control conditions where is below 10 CM per tip in the rainy the parasitoid had access to the pest. season and mostly below 20 CM per tip in Meanwhile a computer simulation model the dry season. CM populations on improv­ is being constructed by the ABCP in col­ ed lIT A varieties usually had about half this laboration with the Universi ty of California, density. Though CM is no longer the same Berkeley, and the Swiss Federal Institute of severe pest insect it was before the introduc­ Technology . The basic parameters concern­ tion of E. lopezi, it still causes occasional ing the cassava plant and the cassava damage in Nigeria, mainly on poor land. mealybug as well as the CM's indigenous Larval development OvIpoaltlon • duration • 1 egg per sting • temperature optimum • superparasitism co • lower thermal thresh hold • number of eggs mortality: 1 larva survives max. 86 per female. encapsulation max. 10 per day • sex-ratio egg & larva in living host ~ Survival • host feeding fraeadult • longevity . Qj' ~ i i 1 ...0,,1) Hoatflndlng ~. :~~ • host plant attraction Emergence • host attraction • Average 40 offspring • host inster preference d • mating Figure 20. The biology of E. lope .. ; which is the most effecli"c beneficial yet in lroduced 10 control cassava mea lybug (eM) in Africa's cassava bell. A co m puler simulalion model, based on Ihese li fe· labh." and wea l her dala, is bein2 developed as a mel hod of measuring Ihe impaci of Ihis beneficial on eM populations. 11 7 predators and E. lopezi have been measured. d'Ivoire and by incorporating these data into A first simulation gave population curves the existing simulation model. similar to those observed in the field. To date, from all three approaches used to For these simulations the biology of E. assess the impact of E. lopezi the following, lopezi has been studied in detail and still tentative, conclusions are drawn: parameters have been quantified (Figure 20). • E. lopez; is an efficient parasitoid over In addition, density dependence of several, but probably not all ecological parasitoid reproduction in the field, impact conditions of the African cassava belt. of hyperparasitoids (See IIT A Annual • While it cannot substantially reduce high Report and Research Highlights 1985), and host populations, it is capable of main­ interactions with indigenous predators were taining the CM populations which exist evaluated and included in the simulation at the end of the rainy season at a low model. Impact on tuber production was level due mainly to its good host· finding assessed by comparing yields in areas with capacity. and without E. lopezi in Ghana and Cote I 18 Exploration for Natural Enemies of Cassava Mealybug and Cassava Green Mites The key factor for success in biological con­ trol is the identification and introduction of effective natural enemies of pests . The pro­ cess of discovering appropriate natural enemies for a given pest is often a long and arduous one which involves systematic and sustained exploration by teams of en­ tomologists. Since 1977. exploration for natural enemies of cassava mealybug has been con­ ducted in Central and South America as part of collaborative efforts between CAB Inter­ national, Institute of Biological Control; Centro Internacional de Agricultura Tropical (CIAT) and IITA. While scientists suspected that the CM was introduced from Central or South American regions to Africa, the actual African eM species was not discovered until 1981 in Paraguay . Real progress on the iden tification of natura] enemies was then possible and eventually Epidinocarsis lopezi, (first described in 1963 from northern Argentina), was identified . Between 1983 and 1986, two en­ Figure 21. Exploration for natural enemies of cassavlI tomologists explored thousands of square mealybug by the Africa-wide Biological Control Project in Central Bnd South America (thick lines = explora­ kilometers in Central and South America but lion route). Recovery of Phenacoccus manihoti (circled discovered only eight areas where CM occur­ dols) and P. herreni (shaded area). red - four in Paraguay, three in Brazil and one in Bolivia, (Figure 21) . CM populations biological information available on COM in these areas were so low that trap plants and associated natural enemies in the heavi ly infested with CM had to be placed in Neotropics. Present knowledge of ecological field s to attract natural enemies . This led to systems is insufficient to predict where further collection of E. lopezi from Brazil useful natural enemies can be found. Conse­ and Colombia. In addition , several other quently the search for natural enemies is still parasitoids and predators were discovered, as much an art as a science. quarantined and sent to IITA. The success Research is underway to generate of E. lopezi in Africa as an introduced ecological profiles that will provide essential natural enemy of CM is now widely information On the relationship between acknowledged . COM population densities and damage to Exploration strategies to discover natural cassava plants. Much of this work relates enemies of cassava green mi tes (COM) are available agrometeorological data to the also being developed by CIA T and IlTA. It biology of cassava and COM. is generally accepted that the challenge here The major aims are to: is very formidab le because of the limited • identify areas in Africa likely to have high I 19 populations of COM . • relate mite population densities to plant damage and yield loss through the use of simulation models . • generate ecological profiles for the major cassava-growing regions of Africa. Through such an approach, scientists will be in a better position to identify the ecological conditions in which pests and their natural enemies survive. The cassava­ growing region in Africa is so vast, and the area of investigation so large, that scientists must resort to predictive models to make assessments of pest and natural enemy in­ cidence, while ensuring that such models are based on the best abiotic and biological in­ formation available. 120 Virology Unit Seed transmission and sanitation One of the UTA Virology Unit's important tasks is to continuously improve the phytosanitary status of breeders' materials that emanate from the institute's crop improvement programs and are selected for international, adaptive testing. The cowpea and soybean international nurseries were subjected to seed transmission tests on breeders materials to be shipped for international testing; 62 cowpea and 9 soybean accessions were screened by standard procedures (grow-out tests with 500 seeds per accession). Tests revealed the absence of CAbMV and SMV, both com­ monly transmitted in seed. Transmission of CuMV was observed in only three cowpea acces­ sions. Consequently is it recommended that they be omitted from the international trials. Detailed studies of reported transmission, through seed, of viruses not yet found to be seed­ borne at UTA have revealed that cowpea mild mottle virus(CMMV) most likely is not seed­ borne in soybean, despite literature reports of transmission of this whitefly-borne virus in soy­ bean seed and in cowpea and french bean seed. Continuous monitoring of the wide spectrum of viruses occurring at UTA, and in areas of seed production of earlier mentioned crops, provides an important safeguard in production of virus-free seed stocks. Sweet potato In an attempt to obtain more information regarding the geographiea] distribution of the virus complex responsible for the sweet potato virus disease (SPVD) in Nigeria, or the possible occur­ rence elsewhere of similar complexes experiments were conducted (for quarantine reasons) at lPO, Wageningen (The Netherlands).The experiments showed that symptomless materials col­ lected or obtained from Zaire, Rwanda, and Gabon all contain potyvirus(es), which (in com­ bination with the whitefly-vectored component of SPVD in Nigeria) develop prominent SPVD symptoms in test clones. So virus diseases in sweet potato in those parts of Africa are caused by a complex of two viruses that are very similar and possibly identical to the SPVD complex in Nigeria. Several virus isolates obtained during our 1985 studies of the 'leaf curl' disease and other virus diseases of sweet potato in Taiwan were characterized in 1986 with further comparative studies at IPO. One isolate obtained by whitefly transmission, that had been isolated from severely diseased plants of a particular clone of sweet potato ('Simon-l '), proved capable of in­ ducing symptoms in UTA's SPVD test clone, 'Tlb 8 s.c.9-A', which represents the one preinfected with the aphid-transmitted component of SPVD. Symptoms developing in this test clone were similar to those commonly seen with SPVD in Nigeria. It thus appears that a whitefly-transmitted agent like the one isolated from SPVD infected plants in Nigeria also occurs in Taiwan, at least in 'Simon-I' clone. Rice The isolate of rice yellow mottle virus (R YMV) used for resistance screening work at UTA was compared at [PO Wageningen with the type strain originally described from Kenya. The comparison was on a set of Oryza glaberrima, O. barthii and O. sativa accessions selected for 121 known resistance or susceptibility to RYMV at IlTA. In general, reactions in susceptible rice varieties used as controls were slightly more severe with the Kenya-isolate than the Nigeria isolate. One O. barthii accession, of 4 accessions tested (TOb 5701), and one O. glaberrima ac­ cession (TOg 7235), of 6 accessions tested, differentiated between the two isolates. No symp­ toms developed in them with the Nigerian isolate, but distinct symptoms developed in them with the 'Kenya' isolate. Maize Reports from India and Zaria indicate that pearl millet is a host for maize streak virus (MSV). All attempts to transmit the Ibadan-isolate of MSV to millet, Pennisetum americanum, cv. ex Bornu, with viruliferous Cicadulina triangula, failed. However, an isolate of streak virus obtained from Bracharia deflexa near Oshogbo was transmitted to millet, but not to maize. Although scientists in Kenya have reported an isometric virus of 40 nm associated with maize stripe disease in Kenya, studies in the USA and at lIT A have failed to confirm the report. Studies in the USA showed maize stripe disease caused by a virus with fine filamentous particles 3 nanometer (nm) in diameter and of undetermined length. On the other hand, maize mot­ Ileichlorotic stunt virus (MMCSV), reported from Nigeria, has 40-nm virus particles. So the 40-nm virus particles reported from maize stripe in Kenya may have been from MMCSV. When we tested purified MMCSV in agar-gel diffusion using maize stripe virus antisera from Kenya and Florida, the antiserum from Florida did not react with purified MMCSV, but both homologous and maize stripe virus antiserum from Kenya did and each formed a confluent band. When we tested crude juice of maize stripe virus diseased maize in agar-gel diffusion tests using the above three antisera, both maize stripe virus antisera from USA and Kenya reacted, but M.\1CSV -antiserum did not. Since the antiserum from Kenya reacted with both maize stripe virus and MMCSV, the 4nm virus particles in maize stripe virus preparations probably are from M~CSV. Cowpea Cowpea severe mosaic virus (SMV) does not occur in Nigeria. It appears to be a virus that more typically occurs in the New World. IITA cannot carry out an 'on-site' resistance screening program for this important virus disease of cowpea, so we had existing elite materials in UTA's cowpea breeding program evaluated for resistance to this virus at Wageningen (The Netherlands) in the Department of Virology of the Agricultural University (C.P. de Jager). As expected, all except 5 accessions (with common ancestry) proved highly susceptible to CSMV. The "K" isolate of cowpea yellow mosaic virus (IITA Annual Report, 1985) was purified and an antiserum produced, which was compared with a previously produced antiserum against :he common strain of CYMV ('isolate 6'), used at IITA for resistance screening. Serological com­ parison of the homologous and heterologous titers of these two antisera between isolates CYMV-K and CYMV-6 indicated that CYMV-K is related to CYMV-6, but they are not iden­ tical. Spur formation was observed between CYMV-K and CYMV-6 and the antiserum titer detectable by heterologous antigen was lower than by the homologous antigen. A new potyvirus from cowpea isolated from a home garden in the Shagamu area did not react with the antiserum to the "Onne" isolate of cowpea aphid-born mosaic virus. Preliminary susceptibility tests of a few cowpea germ plasm accessions and breeding lines, showed only four infected, e.g., TVu 128, IT8ID-1228-14, TVu 3273, and IT83D-442. 122 Bambarra groundnut By examination of samples of bambarra groundnut plants from IITA's experimental plots at Ibadan and at Ikenne, one of IITA's testing sites, the following viruses were positively iden­ tified: cowpea mild mottle virus (CMMV), cucumber mosaic virus (CuMV), and cowpea aphid­ borne mosaic virus (CAbMV). We also isolated a potyvirus (code named 'B-2l ') that is sap transmissible to soybean (Malayan) and cowpea (Ife Brown) and is transmitted nonpersistently by Aphis craccivora. It appears to be a new virus and is under further study. To identify resistance to CMeV, a virus that commonly occurs in bambarra ground nut from which it was originally described, we screened 72 germp]asm accessions representing a cross sec­ tion of bambarra groundnut genetic diversity available in IITA germplasm collection for resistance to CMeV. We identified high resistance, although mostly in segregating form, in the following germplasm accessions: TVsu 762, TVsu 763, Tsu 785, TVsu 872, TVsu 1158, and TVsu 1161. Yam Using the antiserum against yam mosaic virus (YMV) from Cote d'Ivoire (courtesy ORSTOM, Abidjan), in serological studies, we found that purified preparations of Dioscorea rotundata virus from Nigeria reacted with the YMV antiserum in SDS-agar-gel diffusion tests and form­ ed a confluent band with the one formed by homologous antiserum produced against the D. rotundata virus at IITA. Further, when crude juice of Nicotiana benthamiana, inoculated with infected yam samples in Nigeria, was treated with YMVantiserum from ORSTOM and an an­ tiserum produced at IITA against a Nigerian isolate and examined in the electron microscope, potyvirus particles were fully decorated with both antisera. So the YMV reported from Cote d'Ivoire and the one in Nigeria apparently are identical. Cassava We isolated gemini virus from a choyote plant (Sechium edufe. Fam Cucurbitaceae) showing typical symptoms of severe mosaic, distortion and malformation of leaves and stunted growth. This new geminivirus is serologically related to African cassava mosaic virus (ACMV), but is not identical to it. Annual virus disease survey in Nigeria Although southern bean mosaic virus (SBMV) has been described from cowpea grown in Nigeria and was identified by the Virology Unit in 1985 from cowpea samples from northern Nigeria, the virus had not been encountered at IITA, nor had it been found by the Unit during annual surveys in Nigeria. But samples from a farmer's diseased 1986 cowpea crop near los contained SBMV. As in the 1983 and 1984 epidemic years, MSV was epidemic in certain areas of Nigeria during the 1986 rain-fed season, notably the northern part of the southern Guinea savanna region, which was dry during early crop establishment in 1986. Drought conditions have repeatedly been associated with MSV outbreaks in Nigeria. Surveys elsewhere MSV does not seem to be the only important virus of maize in Zaire. During a survey of ex­ perimental fields at the Agricultural Experiment Station, at M'Vuazi (Bas Zaire) maize stripe 123 virus (MStrV) was also commonly seen in their maize plots. For the first time outside Nigeria, symptoms typical of 'African soybean dwarf' were seen in soybean trials at the M'Vuazi station. To identify viruses and virus diseases of cowpea in Senegal, lITA virologists sent antisera to several cowpea viruses to Senegal. In agar-gel diffusion tests there, southern bean mosaic virus (SBMV) was identifies as the causing severe cowpea disease in the Casamance region of southern Senegal. 124 Comparative studies on sweet potato virus complexes worldwide To obtain more information on the SPYD. Symptoms characteristic of SPYD geographical distribution of the virus com­ developed in the earlier test clone that con­ plex responsible for the sweet potato virus tains the whitefly-transmitted component, as disease (SPYD) in Nigeria, or complexes well as in materials tested by grafting to this with similar strong dependencies among in­ test clone. Symptoms that developed by dividual components, we conducted com­ grafting were similar to those observed in parative studies with virus isolates from diseased clones from the countries mention­ various regions in Africa and elsewhere in ed. So virus diseases in sweet potato in other the world at IPO, Wageningen, The parts of Africa are caused by a complex of Netherlands. In these studies it was shown two viruses very similar. and possibly iden­ that symptomless materials collected or ob­ tical, to the SPYD-complex in Nigeria. tained from Zaire, Rwanda, and Gabon all Several virus isolates obtained in 1985 dur­ contain potyvirus(es) that develop promi­ ing studies of the 'leaf curl' disease and other nent symptoms in the test clone that contains virus diseases of sweet potato in Taiwan, the whitefly-vectored component of SPYD. were further characterized in 1986 in conti­ This was readily shown by grafting such nuing, comparative studies at IPO. One symptomless materials to UTA's two SPYD isolate obtained by whiteflies that had been test clones, each preinfected with a different isolated from severely diseased plants of one virus of the two components involved · in particular clone of sweet potato ('Simon-l ') Decorated and und«oraled potyvirus particles in sweet potato after treatment of virus mixture on an electron microscope grid with an antiserum to one of the two viruses. 125 proved capable of inducing symptoms in Nigeria also occurs in Taiwan, at least in IITA 's SPVD test clone, 'Tlb 8 s.c.9-A', clone, 'Sirnon-I '. Also, as in the case of the one preinfected with the aphid­ SPVD, this virus makes 'Virus II ' . the transmitted component of SPVD. Symp­ potyvirus isolated from diseased plants of toms developing in this test clone are similar this clone, detectable when such plants are to those often seen with SPVD in Nigeria. simultaneously infected with it , the same When this whiteny-transmitted isolate was result as established for SPVD. This clone graft-transmitted back to healthy-looking reportedly was brought to Taiwan from plants of clone 'Simon-I', which , previous­ Brazi l. So the complex virus disease of sweet ly had shown no virus under the electron potato found in Nigeria occurs elsewhere in microscope or serologically, the same promi­ Africa, and in other parts of the world . nent symptoms developed. Electron If clone, 'Simon-l ', from Taiwan microscopic studies involving decorating the originated in Latin America, the whiteny­ particles (immunosorbent electron transmitted component of SPVD, and thus microscopy, ISEM) observed with an an­ SPVD itself, may have originated in La tin tiserum prepared for the potyvirus earlier America. The disease may have come with isolated from such plants ('virus II '; see sweet potatoes when they were introduced to IITA Annual Report, 1985) now revealed Africa. fair concentrations of heavily decorated par­ ticles in the plants that had developed symp­ toms, after the whitefly-transmitted virus isolate was introduced. It thus seems that a white ny-transmitted virus like that from SPVD infected plants in 126 Cowpea mild mottle virus (CMMV) is not seed-borne in soybean A thorough understanding of viruses and both viruses, and one with SMV alone. their possible transmission through seed of A maximum of 500 seeds of the diseased crops was the subject of a detailed study con­ plants from each accession in each of the ducted by lITA's Virology Unit in 1986. four series were planted in trays in an insect­ Brunt and Kenton (1972) described proof screen house, 3-4 months after CMMV, a common virus in soybean in harvest. Seedlings obtained were carefully Nigeria, as heavily seed-borne in both soy­ inspected through their first trifoliate leaf bean and cowpea, and to a lesser extent in stage for any visible sign of virus infection. french bean. They reported seed transmis­ Depending greatly on genotype (severity of sion rates of nearly 100"10 in soybean and symptoms in mother plants; seed viability), cowpea. At lIT A, however, in seed the number of seedlings obtained for scoring transmission studies involving the local varied considerably among varieties and 'Malayan' variety (see IITA A nnual Report, among series. Irrespective of isolate of the 1985), and casual observations over the virus or whether seeds were from plants that years, involving numerous seedling lots from were simultaneously infected with SMV, not a great variety of genotypes sent for interna­ a single case of transmission of CMMV tional testing, no such transmission had been through seed was recorded in any accession observed. CMMV is one of commonest tested. Seed transmission rates for SMV viruses in soybean at lIT A and elsewhere in varied from 0-9% with no such transmis­ Nigeria. It has been reported from other sion observed in four accessions. countries in different continents, so it pro­ bably is distributed worldwide. Seed-transmission rates reportedly vary widely from virus to virus and from genotype to genotype, and may even vary by virus strains. At lITA, with viruses like soy­ bean mosaic virus (SMV) and cucumber mosaic virus (CuMV), (cowpea strain), seed­ transmission rates exceeding 15% have been observed in certain genotypes, while other genotypes showed no incidence of such transmission . So a detailed study carefully monitored possible CMMV transmission through seed of 25 soybean genotypes . Ten diseased plants each of the 25 genotypes were infected with CMMV at an early stage and grown to maturity in an insect-proof screenhouse. In two parallel sets, each was inoculated with a different isolate of CMMV. Additionally, to see if transmission through seed of CMMV is influenced by SMV (and vice versa) when both are mixed in the same plants, we tested two more sets, one infected with a mixture of 127 Cowpea mild mottle virus (CMMV) is not seed-borne in soybean A thorough understanding of viruses and both viruses, and one with SMV alone. their possible transmission through seed of A maximum of 500 seeds of the diseased crops was the subject of a detailed study con­ plants from each accession in each of the ducted by /ITA's Virology Unit in 1986. four series were planted in trays in an insect­ Brunt and Kenton (1972) described proof screenhouse, 3-4 months after CMMV, a common virus in soybean in harvest. Seedlings obtained were carefully Nigeria, as heavily seed-borne in both soy­ inspected through their first trifoliate leaf bean and cowpea, and to a lesser extent in stage for any visible sign of virus infection. french bean. They reported seed transmis­ Depending greatly on genotype (severity of sion rates of nearly 1000/. in soybean and symptoms in mother plants; seed viability), cowpea. At IIT A, however, in seed the number of seedlings obtained for scoring transmission studies involving the local varied considerably among varieties and 'Malayan' variety (see JITA Annual Report, among series. Irrespective of isolate of the 1985), and casual observations over the virus or whether seeds were from plants that years, involving numerous seedling lots from were simultaneously infected with SMV, not a great variety of genotypes sent for interna­ a single case of transmission of CMMV tional testing, no such transmission had been through seed was recorded in any accession observed. CMMV is one of commonest tested. Seed transmission rates for SMV viruses in soybean at IITA and elsewhere in varied from 0-9% with no such transmis­ Nigeria. It has been reported from other sion observed in four accessions. countries in different continents, so it pro­ bably is distributed worldwide. Seed-transmission rates reportedly vary widely from virus to virus and from genotype to genotype, and may even vary by virus strains. At !ITA, with viruses like soy­ bean mosaic virus (SMV) and cucumber mosaic virus (CuMV), (cowpea strain), seed­ transmission rates exceeding 150/. have been observed in certain genotypes, while other genotypes showed no incidence of such transmission. So a detailed study carefully monitored possible CMMV transmission through seed of 25 soybean genotypes. Ten diseased plants each of the 25 genotypes were infected with CMMV at an early stage and grown to maturity in an insect-proof screenhouse. In two parallel sets, each was inoculated with a different isolate of CMMV. Additionally, to see if transmission through seed of CMMV is influenced by SMV (and vice versa) when both are mixed in the same plants, we tested two more sets, one infected with a mixture of 127 International Cooperation and Training Program The Institute's International Cooperation and Training Program activities in 1986 were developed to meet one of UTA's major tasks, i.e., ensuring that technologies developed through research reach the potential beneficiaries, including national research programs, farmers and ultimately consumers of agricultural products. During the year, UTA had 42 staff engaged in collaborative research activities with various national programs in six African coun­ tries (Table 41). In addition, 19 comprehensive training programs were conducted on-site (Ibadan) and 15 in countries throughout sub-Saharan Africa (Tables 42 and 43). A major review in 1986 of the Institute's activities in Zaire found that substantial progress had been made in the first year of the expanded research program, that was initiated in 1985. The evaluation focused on two major areas: • the effective incorporation of farming systems research and economics into the three national commodity programs: Programme National Manioc (PRONAM), Programme National du Mais (PNM) and Programme National Legumineux (PNL) . • institution-building with special emphasis on the managerial and organizational structure of the program. In 1986, lIT A accepted the responsibility of establishing a maize and cowpea collaborative research network under Phase II of the Semi-Arid Food Grain Research and Development (SAFGRAD) Program. The networking mechanism allows participating SAFGRAD member countries to share research results and related information. UTA continued its support of the networks through activities of our resident commodity research teams responsible for develop­ ing improved maize and cowpea technologies. A major focus of lITA 's technical assistance in Phase II of the Cameroon National Cereals Research and Extension Project (NCRE) was to increase Testing and Liaison Unit (TLU) ac­ tivities. Using the farming systems approach, the TLU's began evaluating specific cultural practices in major maize-growing areas in Cameroon. Varietal improvement of rice, maize, and sorghum through on-station research continues to receive the major portion of IITA's effort. Phase III of Cameroon's National Root Crops Improvement Program (CNRCIP) was ter­ minated as planned with the termination of funding by the International Development Research Centre (IDRC) Canada and the General Agency for Development and Cooperation (AGCD) Belgium in September 1986. A major funding of the joint terminal evaluation, conducted in July 1986 by IDRC, AGCD, UTA, and the National Research Institution (IRA), was that superior sweet potato, cassava, and yam clones developed through breeding and selection work were now available for multiplication and distribution throughout Cameroon's major agro-ecological zones. The Rwanda National Root Crops Improvement Program (RNRCIP), with IDRC financial support to develop a strong national cassava and sweet potato program, terminated in December 1986. The program produced elite cassava and sweet potato clones (selected from UTA's source material) that are being mUltiplied and distributed to schools, agricultural pro­ jects, and farmers for large-scale diffusion. 128 IITA's assistance to Ghana in 1986 continued technical support to expand Ghana's Legume Breeding Program by helping to develop high-yielding cowpeas. Several extra-early maturing varieties were tested in two major agro-ecological zones in 1986 for yield performance. disease incidence, and other agronomic attributes. Cowpea varieties capable of producing grain yields of 1,000 to 1,400 kg/ ha with no applied fertilizer are being used to develop a strong national cowpea program in Ghana. Seeds of IT82E-32 cowpeas have been mUltiplied for commercial cultivation, and farmers have started growing it in the forest zone. In 1986 lIT A continued efforts to identify and test improved cowpea and soybean genotypes adapted to the ecologies and cropping systems of East Africa. Several cowpea and soybean lines have shown good potential for future adoption, based on their disease and insect resistance, plant type, seed characteristics, and yields. lIT A continued efforts in 1986, through its many training programs to develop manpower capable of transferring agricultural research and technology to national programs. The 976 who received training at IITA in 1986 included, for the first time, participants from the Peoples' Republic of China, Norway, EI Salvador, Grenada, Guatemala, Saint Kitts , and Ms Yamala Tonga. Zambia and Mrs. AnUng Ding, Peoples Republic of China evaluate cowpea lines during field pro­ jects undertaken as part of the first international training course on Cowpea and Soybean Research and Production conducted by DTA . 129 Table 41. Bilaleraland multilaleral collaborative projects. 1986. Total Life budget Project name Location Donor staff $x 1000 Semi-Arid Food Grains Development (SAFGRAD) Burkina-Faso 5 6,049.2 USAIO Food Legumes Burkina-Faso 1,672.9 IDRC Cameroon National Cereals Cameroon 13 14,309.7 USAIO Cameroon National Root Crops Cameroon 299.5 IORC 300.0 Belgium 402.3 Gatsby Found. Cameroon FSR Cameroon 252.6 IORC Zaire Applied Research Zaire 14 2,835.0 USAID Rwanda FSR1 Rwanda 2 268.9 World Bank Rwanda Root Crops 161.5 IDRC Ghana Grain Legumes Ghana 703.4 CIOA Maximizing Grain Legume Production through BNt·2 Nigeria/Tanzania 2 1,500.0 UNDP 1. FSR = Farming Systems Research 2. BNF = Biological Nitrogen Fixation Tuvalu. This represents a 32"1. increase from 1985, which was primarily from 14 off-site group courses conducted in conjunction with national and regional institutions. Outreach training courses were conducted at the UTAI Benin sub-station at Cotonou in the Republic of Benin, and also in Cameroon, Mexico, Nepal, Malawi, Rwanda, Liberia, Sierra Leone, Tanzania, and Zanzibar in addition to 20 group courses at I1TA. The 80 participants registered for higher degrees in 1986 set a record for lIT A. In the degree­ related training program, postgraduate students from universities throughout the world con­ ducted fieldwork portions of their degrees at liTA , supervised by Institute scientists. These programs are primarily for students from humid and subhumid tropics so fieldwork is usually with tropical crops, soils, and systems like those to which they return when they complete their degree programs. During 1986, 35 M.Sc. degree candidates and 45 Ph.D. degree candidates did research at I1TA in Ibadan. They came from 29 countries, 19 of which are in Africa, and from 39 univer­ sities, 16 of which are in Africa. At year's end, 4945 participants had been trained at UTA since training began in 1970. 130 Table 42. Groups courses at lIT A, Ibadan, in 1986. Course title Number ot Number of countries Language) participants represented I. Cowpea and Soybean Research and Production, 6 Jan. - 28 February 33 19 ElF 2. Biocontrol of cassava Pests: I 28 Jan .. 15 February 10 5 ElF 3. Soil and Plant Analysis LO Feb .. 14 March 29 15 ElF 4. Cowpea Production 3 . 7 February 28 E 5. Hybrid Maize Seed Production LO· 21 February 40 E 6. Training Course in Improved VVeed ~anagement 3 ·21 March 16 4 ElF 7. Soil and VVater Conservation Training Workshop 17 . 28 March 21 II ElF 8. Statistics in Agricultural Experimentation 7 - 25 April 26 13 ElF 9. Food Crop Research and Production 7 April· 2 May 39 10 ElF 10. Alley Cropping and Alley Farming 5 - 21 May 34 17 ElF 11. Tropical Root and Tuber Crops Research and Production 2 May· 11 July 35 16 ElF 12. Intensive Cowpea and Soybean Course for Nigerian Agricultural Development Projects 26·29 May 29 E 13. Plantain/Banana Production 17 July· 15 August 18 12 ElF 14. Biocantrol of Cassava Pests: II 2 . 17 June 9 4 ElF 15. Root and Tuber Crops Tissue Culture II - 29 August 12 II E/P I31 16. African Regional Center for Engineering Design and Manufac- ture Training Course 1 - 30 August 18 12 ElF 17. Seed Technology Training Course for Cassava and Other Vegetative- ly Propagated Crops 2 - 12 September 19 E 18. Rice Research and Production 1 September - 19 December 22 12 ElF 19. Cowpea and Soybean Research and Production 13 Oct. - 5 December 38 23 ElF Total 476 I. E English; F French; P Portuguese Table 43. Group courses at outreach locations in 1986. Center where course Number of Number of Course title was conducted participants countries Languagel represented I. Root and Tuber Crops IRA, Ekoma, Cameroon 26 E Research and Production 29 Sept. - 4 October 2. Cassava and Sweet Potato Bvumbwe Research Research and Production Station, Malawi 27 E 14 - 25 October 3. IITAIISAR Root and Tuber ISAR. Rubona Crops Research and Production Rwanda 28 F JO - L9 November 4. Root and Tuber Crops Kizimbani Research Research and Production Station. Zanzibar 30 E Training 24 Nov. - 6 December 5. Root and Tuber Crop Agric. Research Research and Production Institute. Ukiriguru. Training Mwanza. Tanzania 19 E 1 - 13 December 6. Cassava and Sweet Potato Suakoko Research 29 E Research and Production Station Liberia. 30 Nov. -6 December 132 7. Food Crops Utilization and NjaJa University Nutrition Training College, Sierra Leone 28 E 15 - 20 December 8. Postharvest Food Loss I1TA/Benin sub-station Prevention Training Work- Cotonoo, Benin Rep. 27 14 ElF shop 10 - 28 November 9. Regional Cowpea aoL. Sokoine University of Soybean Research and Agric., Morogoro, Production Training Tanzania 21 10 E 27 Jan. - 7 March 10. Cowpea and Soybean B\lumbwe Research Research and Production Station, Malawi 37 E Training 1 - 12 April I!. Cowpea and Soybean Tampico Tamaulipas. Research and Production Mexico 23 12 S Training 29 Sept. - 31 October 12. Cowpea and Soybean UTA/Benin sub- Research and Production Station Cotonoll. Training Benin Rep. 25 6 F 29 Sept. - 7 November 13. Cowpea and Soybean Katmandu, Nepal 19 E Research and Production Training 10 - 19 September 14. Maize Research and IlTA /Benin sub- Production Tralning Station Cotonou. 8 - 19 September Benin Rep. 22 F 15. Rice Research and Production Sokoine University of Training Agric., Morogoro. 21 April - 30 May Tanzania 19 E Total 380 1. E = English; F = French; S = Spanish. 133 Documentation, Information, and Library Program Documentation, Information, and Library Program (OIL) is responsible for carrying out the information-related mission of the Institute. The functions of OIL include: • Puhlishing and disseminating research findings to scientists, policy makers, national research programs, development and extension personnel, and others con­ cerned with or interested in the agriculture of the subhumid and humid tropics. • Developing a library with a comprehen­ sive collection of pertinent Literature on Learning how to search the library data base: Library tropical agriculture for use by Institute starr conducted 29 training sessions during the year to scientists, trainees, and other scholars. ensure that all active users can use the new computerized system errectively. • Providing logistical support for con­ ferences, symposia, and workshops and coordinating an active seminar program trammg sessions. As a result, most active in which staff, trainees, and visitors par­ library users now know how to search the ticipate . library data base . Training of users will be a • Providing interpretation and translation continual activity. A simple reference services to support the communication manual has been written and will be printed and training efforts of the Institute. for distribution in 1987 . The library data base is currently searchable on 60 terminals To carry out these functions, OIL is located around the Institute . This means that organized into the following units: Library it is possible to search the collection of the and Documentation Center; Publications; library at any time from 60 locations even Public Affairs; Graphics and Printing; when the library is closed . Audiovisuals and Photography; Conference and Visitors' Center; and Interpretation and Translation. Highlights of the activities of these New titles published constituent units of OIL follow. The Research Highlights publication was modified and many new titles were published Library automation in 1986. Modifications of the lITA Research Development of the integrated computerized Highlights in 1986 included a longer write-up library system continued during 1986. on IlTA, a new section on the CGIAR Refinements were made in the system to system, a Director General's Report, and ex­ make it more user-friendly. The online data ecutive summaries of individual programs. base had 46,700 records at the end of 1986. These modifications resulted in a well­ Before 1986, few library users knew how rounded, highly informative and cost­ to do online data base searching. During effective publication titled lITA Annual 1986, Library staff conducted a total of 29 Report and Research Highlights. The French 134 edition, Rapport Annuel eT Point de la Recherche de I'IITA , was also published . The JITA Annual Report was discontinued and replaced with more comprehensive in­ dividual program reports produced inexpen­ sively . Echo de I'JITA, the French-language ver­ sion of JITA Research Briefs, was started in 1986. Two issues were published but it will become a quarterly publication from 1987. Echo de I'JITA will further improve com­ munication with national programs and in­ dividual scientists in the Francophone areas Publishing for a wider readership: In addition (0 annual reports, quarterly publications, brochures and of llTA' s geographic mandate. Four issues monographs, UTA published Echo de I'IITA, the of JITA Research Briefs were produced on French language version of the llTA Research Briefs schedule and distributed worldwide through especially for national research programs in Frnn­ the KLM distribution service. Two news­ cophone countries. letters were also started in 1986 to improve communication among members of research • A Guide to Hybrid Maize VarieTies and networks to which llTA belongs. These were Parental Lines in Nigeria; and The Tropical Root Crops NeTwork News­ • Manuel de Production de Semences de leller, and the WeST African Farming Mais Hybride. Systems Research Network Bulletin. Two edit ions of the latter. French and English, Audio-tutorial modules are published. The development and production of audio­ New monographs and brochures publish­ tutorial modules was a major activity in ed during the year include: 1986. Ten topics were initially selected by the • Virus Diseases of Important Food Crops Grain Legume Improvement Program . Each in Tropical Africa; module includes a set of 35-mm color slides, • The Wetlands and Rice in sub-Saharan a printed script/workbook in English and Africa; • Common African Pests and Diseases of Cassava, Yam, Sweet Potato and Cocoyam; • Les Principaux Ravageurs et Maladies d'Afrique: Manioc, Igname, PaTate Douce. Aracees; • Establishing, and Managing Alley Crop­ ping PlOTS; • Establissement et Entrelien des Cultures en Couloirs; • GLIP Training at JITA during 1971-85; • Le Mais. Publications en Langue Fran­ caise Disponsibles a la Bibliotheque de I'JITA; Improving communication and presentation of (raining modules: Audio-tutorial modules that consist of II slide • The JITA High Rainfall Substation Onne, set, audio lape and workbook were produced for the Nigeria; Grain Legume Improvement Program. 135 French, and audio tapes in English and in the tables are modest. French. The modules are designed to work The number of visitors to UTA increased on any slide projector and tape recorder or in 1986. The increase is attributable to better audioviewer. Cassettes are recorded on one awareness of, and recognition of !ITA's side with an audible 1000 Hz pulse for work, as well as the vastly increased interest automatic presentation. A media file holds in farming among Nigerians. The visitors to the complete package. The work on the first UTA in 1986 included eminent scientists, 10 modules is being done in collaboration ambassadors, government officjals~ with the Training Program and it is about members of professional and social societies~ 8007. complete. groups of college and high school students, and individual farmers seeking information Media Coverage and advice. UTA's research and training activities Table 45. Other :o-Jewspaper Articles on IITA (1985 and received considerable and highly positive 1986) coverage in the mass media during 1985 and Newspaper title Country of 1986. All types of media - radio, television, publication newspapers, and magazines - reported on our work. The most frequent coverage was L'Avenir du Luxembourg Luxembourg The Bangkok Post Thailand in the Nigerian media (Table 44). But Cameroon Tribune Cameroon coverage in other countries was also con­ Christian Science Monitor U.S.A. siderable (Tables 45 and 46). It should, Corriere della Sera Italy however, be noted that we do not always see La Cote Libre Belgium Le Courrier de I'Escaut Belgium or hear about everything published, so data Le Courrier de la Bourse Belgium Le Courrier de Verviers Belgium Table 44. Nigerian New'spaper Articles. on lITA 1985 La Croix du Benin Benin and 1986 Dagens Nyheter Sweden Daily Gleaner Jamaica Newspaper title Number of articles Daily Times Malawi 1985 1986 Delta Democratic Times U.S.A. Dong South Korea Business Concord 7 20 L'Echo de la Bourse Belgium Business Times 3 3 L'Echodu Centre Belgium Community Concord 5 Financial Times U.K. Daily Sketch 8 13 Gallup Independent U.S.A. Daily Times 12 12 Giornale di Agricultura della Financial punch 1 Domenica Italy The Guardian 5 20 Grand Rapid Press U.S.A. National Concord 4 7 Le Journal de Mons Belgium New Nigerian 10 29 Maryvill (Tennessee) Times U.S.A. Nigerian Herald 1 ~inneapolis Star Tribune C.S.A. Nigerian Tide 1 2 New York Times U.S.A. Nigerian Tribune 13 27 Nord-Eclair (Mouscron) Belgium The Punch 3 Oceanside (Calif.) Blade-Tribune U.S.A. The Statesman 2 Peoples Daily Graphic Ghana Sunday Glory 5 The Pioneer Ghana Sunday Guardian 1 5 The Plain Dealer U.S.A. Sunday Sketch 6 9 Le Rappel (Charleroi) Belgium Sunday Standard 1 Schenectady Gazette U.S.A. Sunday Times 3 2 Le Soir Belgium Sunday Tribune 1 The Sunday Gleaner Jamaica Sunday Vanguard 1 The Sunday Times Kenya The Vanguard 1 The Sunday Tribune Ireland Telegraphic (New Hampshire) U.S.A. Total 77 167 Vers l'Avenir (Namur) Belgium 136 Table 46. Magazine Articles on lITA 1985 and 1986 Y1agazine Country of publication Number of articles 1985 1986 African Farming U.K. 3 5 African Guardian Nigeria I America U.S.A. I Caribbean Farming Jamaica I Cassava Newsletter (CIAT) Colombia 1 Ceres (FAD) Italy 1 Development & Co~operation W. Germany 3 FAO Gazette Italy 1 IDRC Reports Canada 1 International Agricultural Development U.K. 3 4 Inter Tropiques France 1 Newswatch Nigeria 3 2 Standard Chartered Review U.K. 1 The Catalyst Nigeria 1 The Geographical Magazine U.K. Topic U.S.A. I Tropical Farming & Food-Processing Nigeria 2 I U.B.A. Monthly Business Nigeria 2 West Africa U.K. 1 Total 20 22 Workshop and Conferences lIT A sponsored or co-sponsored 10 workshops and conferences. The staff of the Interpretation and Translation Unit provided simultaneous interpretation for three major international conferences. and 13 intensive production training courses. They translated about 4000 pages of French text from English originals. Among the texts translated were the IITA Annual Report and Research Highlights 1985 and the scripts for Echo de I'IITA. 137 Genetic Resources Unit During 1986, GRU explored new areas for germplasm of cowpea, rice, and their wild relatives to increase and conserve diversity in plant breeding. The unit continued its basic functions of multiplying/rejuvenating, characterizing, documenting, conserving and distributing germ­ plasm. It also studied the genetic inheritance of purple-colored cotyledons, which could be a useful gene marker in cowpeas. The unit made some interspecific crosses between cultivated cowpea and wild Vigna species and, with assistance from IITA's Tissue Culture Laboratory, established an embryo-culture medium for Vigna species. Collaborating with IITA's Quality Laboratory, the unit studied Italian Instituto Nazionale della Nutrizione, selected cowpea and wild Vigna germplasm access­ ions were analyzed for their nutritive values and anti-nutritive factors, looking for variations sions were analyzed for their nutritive values and anti-nutritive factors, looking for variations that could be exploited to improve cowpea quality. Special project support permitted the unit to multiply, characterize, evaluate, and document the entire existing collections of Bam barra groundnut and to assess yields of some of the selected germplasm accessions. Modern new seed stores and seed laboratory were constructed during 1986, to be commis­ sioned in March 1987 and used by the unit for germplasm conservation. Germplasm exploration and acquisition Germplasm exploration increased during 1986 with missions in Senegal, Mali, and Italy to ex­ plore and collect germplasm of interest to IITA. We gathered 919 germplasm samples compris­ ing 384 cowpea, V. unguiculata subsp. dekindtiana, 44 wild Vigna, 46 Bambarra groundnut, 99 O. saliva., 51 O. glaberrima, 45 wild Oryza, and others. The unit also acquired, through ex­ change or donation, 710 germplasm samples that included 389 rice, 263 cowpea, 25 soybean, 19 Bambarra ground nut, 5 wild Vigna and 4 maize. Germplasm multiplication, rejuvenation, and distribution The unit continued to multiply/rejuvenate, characterize, and document the germplasm it main­ tains, now more than 26,000 accessions of various grain crops - work necessary to preserve the germplasm and to provide materials and information to IITA and other scientists throughout the world. In 1986, about 8,500 germ plasm samples of cowpea, including wild Vigna species, rice, soy­ bean, and Bambarra groundnut, were multiplied/rejuvenated, either in the fields or glasshouse. Harvested seeds were processed, for storage in active collection or for long-term conservation. During the year, about 1,400 accessions of cowpea were characterized for up to 30 agronomic and botanical characters, more than 800 accessions of rice for up to 43 characters, and more than 1,200 accessions of Bambarra groundnut for up to 30 characters_ The characterization data and others on passport information on germplasm accessions were routinely updated into the computerized data file, so germplasm information may be retrieved rapidly. GRU responded to more than 200 requests for about 7,000 seed samples of various crop germ plasm maintained by the unit, more than 2,000 of which went to agricultural workers and non-liT A scientists in 29 countries during 1986. 138 Purple cowpea cotyledons as a gene marker A gene marker could be used as an indicator in selecting genotypes from a segregating popula­ tion_ Gene markers appearing at the seedling stage could reduce the time and simplify selection. During 1986, a large collection of cowpea germ plasm accession is were evaluated at the seedling stage for characters that can be used as gene markers. Ordinary cotyledons of cowpea are either yellowish cream, pale green, or green, but some turn purple, 3 to 6 days after seedling emergence. Sixty (2.2"70) of approximately 2,700 accessions that we evaluated, had purple cotyledons 3-6 days after seedling emergence. Crosses are being made to study the genetic in­ heritance of these characters. Embryo culture of Vigna species. In 1985, thousands, of pollinations were made for crosses between cowpea and three wild Vigna species, V. vexillata, V. oblongijolia, and V. gracilis, to exploit the gene pool of wild species and enhance the genetic background of cowpea. Even though all crosses failed, we discovered that treating flower buds, with hormones before and after pollination prolongs pod development. We again made hundreds of interspecific crosses with hormone treatments on flower buds using various concentrations and combinations of different hormones. We obtained no hybrid seeds but identified embryo-culture media that can be used to rescue immature embryos of interspecific crosses. Embryos excised from 6-day-old pods produced by self-pollinated flowers of two cowpea cultivars, TVx 3236 and IT84E-124, and one variety of V. vexillata, were used as materials. Our basic medium was Murashige and Skoog(MS) medium supplemented with 0.1 mg/L Thiamine hydrochloride, 0.5 mg/L pyridoxine hydrochloride, 0.5 mg/L nicotinic acid amide, 1 mg/L glycine, 100 mg/L inositol, 5"70 sucrose, 0.7 "70 agar, and the followkng additives: I) kinetin and napthalene acetic acid (NAA); 2) Kinetin, NAA and coconut milk; 3) kinetic, NAA and cowpea-embryo extract; and 4) cowpea-embryo extract. Of the four culture media tested, only the one with cowpea-embryo extract without kinetin or NAA, i.e. additive No.4, was successful. Four days after culturing, the embryos of the two cultivars and V. vexillata turned from whitish to pale green and showed signs of swelling. They continued to develop into plantlets; 6 to 7 weeks after culturing in the medium, they were transplanted into soils in pots. The success rates of obtaining plantlets from excised young em­ bryos in this medium ranged from 60"70 to 100"70. Plantlets could easily be established in soil which indicates that the culture medium should be suitable for a wide range of genotypes and perhaps also for interspecific crosses. 139 Roster of Long-serving Personnel On our 20th anniversary year, the Management of UTA thanks and recognizes, through this medium, all persons who have served the Institute for 15 years or longer. A.D. Abifarin. rice breeder, 17 years S.O. Amiolemen, groundsman superintendent, 18 years R.A. Adedeji, telephone superintendent, 19 years R.O. Amole, derk, 18 years R. Adegoke. foreman groundsman, 20 years L.L. Amoo, establishment laborer, 18 years S.A. Adegoke, establishment laborer, 18 years J. Amusan, field assistant, 17 years Y. Adekanbi. senior field assistant, 16 years R.O. Arowosafe, se'lior chauffeur, 18 years M.A. Adekoya. senior insurance officer, 17 years E. Atagana, research technician, 15 years A.A. Adeleke, groundsman, 19 years E.A. Awosemo, senior carpenter, 15 years S.A. Adeniyi, assistant research technician, 15 years D.O. Awotide, senior assistant accountant, 18 years J .B. Adenuga, personnel officer, 17 years L.A. Ayanwale, research technician, 15 years M.F. Adeoye, field assistant, 15 years J.1. Ayewoh, chauffeur, 17 years J.A. Adesanya, research technician, 16 years T.E. Ayinde, assistant research technician, 15 years W. Adetunji, assistant custodian, 15 years G.A. Ayodele, mechanic, 16 years M.A. Adewale. senior mason, 15 years D.O. Babatunde. foreman custodian. 15 years E.O. Adeyemo, research technician, 17 years M.O. Babatunde, senior groundsman. 16 years P. B. Adeyemo, passages superintendent, 15 years E.A. Bamidele, senior farm superintendent, 17 years F. Adigun, senior equipment operator, 19 years T .0. Bamidele. research technician, 17 years S. Adigun, establishment laborer, 15 years A.C. Butler, building and site services officer, 19 years J .0. Adinkwuye, accounting assistant, 16 years F.E. Caveness, nematologist, 18 years A. Aigbefoh, senior receiptor/cashier, 15 years J .G.H. Craig, director, PPS. 20 years N.A. Aiki, custodian, 15 years E.M. Dada, computer technician, 16 years R. Aiki, establishment laborer, 15 years H.I. Ebong, transport superintendent, 21 years W. Airebamen, senior mechanic (electrician), 16 years F.B. Egberongbe, foreman mechanic (gas), 15 years A. Ajadi, stores assistant, 20 years M.A. Ehumadu, laundry supervisor, 16 years O. Ajagbe, establishment laborer,I5 years A.A. Emiola, senior mechanic, 15 years L. Ajani, establishment laborer, 20 years J.P. Eneji, senior security guard, 16 years O. Ajao, assistant research technician, 15 years L. Ezeukwu, head steward, 15 years S.L. Akanbi, groundsman, 20 years B.K. Fadare, senior photographer, J 5 years B. Akande, stores attendant, 18 years P.F. Fagbemi, typist, 15 years M.A. Akande, assistant custodian, 15 years O.O.A. Fawole, automotive services officer, 15 years P. Akande, senior field assistant, 15 years S.S. Fowosire, foreman despatcher, 21 years S. Akande, assistant groundsman, 19 years B.A. Gbadamosi, senior research technician, 15 years A. Akangbe, establishment laborer, 17 years S.K. Hahn, director, TRIP,I6years J .R. Akangbe, assistant groundsman, 20 years P. Ibhanesebor, senior receiptor/cashier, 15 years K.L. Akana, senior groundsman, 15 years W.A. Ibikunle, senior foreman mason, 15 years O. Akinbode, assistant research technician, 15 years B. Ibok. assistant research technician, 15 years E.O. Akintokun, research vehicle services officer, 20 S. Ichi, head cook, 16 years years P.O. Ige, senior carpenter, 15 years J.~. Akinwande, senior research technician, 15 years G. Ihenacho, head cook, 17 years V.E. Akpan, senior custodian, 15 years A. lmakuson, research technician, 17 years G .A. Alabi, mechanic, 15 years E.N. Inyang, foreman electrician, 17 years J. Alabi, establishment laborer, 17 years L. Ishola, establishment laborer, 17 years O.B. Alabi, establishment laborer, 15 years M. Ishola, establishment laborer, 15 years S. Alabi, assistant groundsman, 18 years A.S.R. Juo, soil chemist, 17 years R.O. Alagbe, establishment laborer, ] 7 years B.T. Kang, soil scientist, 18 years W.K. Alagbe, field assistant, 15 years S. Kayode, senior groundsman, 17 years F. Alamu, establishment laborer, 18 years A.O. Kehinde, senior mechanic, 15 years L.R. Alamu, establishment laborer, 19 years B.A. Kehinde, principal stores superintendent, 17 years O. Alamu, establ ishment laborer, 20 years W.O. Kolapo, cashier, 16 years S.A. Alamu, establishment laborer, 16 years R. Lal, soil physicist, 17 years W.A. Alawode, research technician, 15 years D. Lanshebe, foreman artisan, 16 years M. Y. Alayande, senior tailor, 15 years L.O. Lasisi, assistant research technician, 17 years M.D. Ale, senior accounts clerk, 15 years A. Lawai, senior security guard, ]6 years A. Alii, foreman plumber, 16 years S.M.A. Lawani, director, DIL, 18 years M.A. Aluko, senior bindery superintendent, 15 years T.L. Lawson, director, IITA-Benin Station, 15 years M.A. Amajo, electronics superintendent, 16 years B.F. Moses, assistant research technician, 15 years M. Aminu, senior groundsman, 18 years A. Mosudi, assistant custodian, 15 years 140 M.A. Nwaogwugwu, research associate, 15 years E. Nwosu, senior groundsman, 18 years G.I. Nwosu, senior shipping officer, 17 years L.A. Odeniyi, assistant research technician, 15 years S.N. Odoemene, assistant research tec:hnician, 15 years M.A. Odu, senior library assistant, 17 years H. T. Ogundimu, executive secretary, 15 years S. Ojo, senior research technician, 16 years S. Oketumo, research technician, 17 years S.O. Okogba, senior foreman carpenter, 17 years F. Okon, head cook, 16 years G.1. OIalere, assistant research technician, 16 years G.O. Olaniran, senior equipment operator, ] 5 years M. Oianiyi, senior groundsman, 19 years A. Olapade, establishment laborer, 17 years J .A. Olatunji, senior groundsman, 19 years K.A. Olubakin, senior chauffeur, 19 years S.O. Olubode, research associate, 15 years J. Oiugbade, chauffeur, 15 years M.E. Olusa, administrative assistant, 16 years A.A. Onashile, senior executive secretary, 15 years C. Onayeraye, stores clerk, 15 years S.A. Opakunle, senior foreman mechanic, 15 years S. Osinowo, foreman carpenter, 18 years S.E. Otokpen, binder, 15 years S. Owa. establishment laborer, ] 7 years Y .A. Oyediran, foreman machinist! fitter, 20 years Y .A: Oyedokun, establishment laborer, 16 years 1.0. Oyekan, head, public affairs, 15 years LL Oyelami, senior clerk typist, 17 years E.O. Oyewole. senior administrative assistant, 16 years J.O. Oyewole, foreman sprayer, 15 years W.A. Popooia. foreman carpenter/wood machinist, 15 years R.A. Raji. research associate, 16 years T. Salawu, groundsman, l5 years M.A. Sanusi, equipment operator, 19 years L. Shitu. assistant research technician, 15 years A.K. Shiwoku, senior administrative assistant, 16 years R.O. Shoyinka, personnel manager, 19 years S.B. Sole. assistant research technician, 16 years 1. Tijani, senior custodian, 15 years G.F. Wilson, agronomist, 16 years 141 List of Principal Staff Administration L.D. Stifel, Ph.D., director general P. Dorosh. Ph.D., agricultural economist B.N. Okigbo, Ph.D., D.Se., deputy director general A. Evers, Ir., water management engineer'" J. W. Pendleton, Ph.D .• deputy director general H.C. Ezumah, Ph.D., agronomist (research)· C. Garman, M.S., agricultural engineer J.H. Davies, B.Sc., deputy director general T. Gebremeskel, Ph.D., agricultural economist (management) B.S. Ghuman. Ph.D., soil scientist, Okomu \1.A. Akintomide, B.S., AleTA, director for M. Gichuru, Ph.D., agronomist/soil scientist administration A. Goldman, Ph.D., economic geographer D.N. McDonald, CA, acting director of budget and H. Gunneweg, Ir., water management engineer'" finance N.D. Hahn, Ph.D., head, Socioeconomics Unit S.E. Adaiumo, M.Sc., E.E., computer/electronics and N. Hulugalle, Ph.D., soil scientist, Burkina Faso operation officer C.A.A. Huysmans, Jr., socioeconomist, Bida· B.A. Adeola, FC[S, Accountant B.T. Kang, Ph.D., soil scientist/agronomist; coor- K.A. Aderogba. J.P., FeISt principal administrative dinator of research on agroforestry and plantains officer R. Lal, Ph.D .• soil physicist; coordinator of research on T.A. Akintewe. M.R.C.P. (U.K.), medical officer upland production systems J.~. Badaki. B.A., M.B.A., human resources manager P. Lippold, Ph.D., LSAID Liaison scientist ~.N. Eguzozie, B.Sc., computer programmer S.K. Mughogho, Ph.D., agronomist'" C.A. Enahoro, manager,lkeja Guest House K. Mulongo)" Ph.D., soil microbiologist D.L. Fennell, administrative assistant to the director H.J.W. Mutsaers, Ph.D., agronomist and coordinator general of on-farm research L.A. Hughes. SRN. SCM, senior nursing sister N.C. Navasero, B.S., agricultural engineer E. hars, B.S., manager, International House M.e. Palada. Ph.D., agronomist R. Martins, M.Sc., systems analyst M. Price, Ph.D., agronomist and project manager-, L.J. McDonald, B.A., LL.B., computer manager Rwanda· 0.0. Ogundipe, M.D., senior medical officer R. Swennen, Ph.D., plantain agronomist, Onne R.I. Olorode, security superintendent A.B.M. van der Kruijs, Ir., agronomist, Dnne M.E. Olusa, administrative assistant to the director for D. Vuylsteke, Ir., plant physiologist, Dnne administration T.D. Oluyemi, M.Sc., computer programmer T. Wakatsuki, Ph.D., visiting soil scientist 0.1. Sewell, manager, aircraft operations G.F. Wilson, Ph.D., agronomist J.c. Seymour·Griffin, FCA, ATIl, internal auditor R.O. Shoyinka, B.S., personnel manager W.M. Steele, Ph.D., special assistant to the director general Grain Legume S.l. Udoh, AMNIM, chief accountant Improvement Program A. Yusuf. B.S., controller of stores S.R. Singh, Ph.D .. program director A. Acosta-Carreon, Ph.D., training coordinator V.D. Aggarwal. Ph.D., cowpea breeder, Burkina Faso Resource and Crop L. Akundabweni. Ph.D., co""pea breeder Management Program A.M. Alghali, Ph.D., entomologist R.A. Amable, Ph.D., agronomist, Tanzania L.L. Bello, Ph.D., soybean breeder D.S.C. Spencer, Ph. D., program director (from June H.S. Chiang, Ph.D., entomologist 1986) K.E. Dashiell, Ph.D., soybean breeder A.S.R. Juo, Ph.D., program director (to June 1986); 1. Ehlers, Ph.D .• cowpea breeder, Kenya coordinator, research on wetland production systems M.A. Hossain, Ph.D., cowpea breeder, Ghana J.A. Akinwumi, Ph.D., visiting economist L.E.N. Jackai, Ph.D., entomologist 1.0. Akobundu, Ph.D., weed scientist E.A. Kueneman, Ph.D., soybean breeder,Brazil· M. Ashraf. Ph.D., agricultural economist ~. Muleba, Ph.D., cowpea agronomist, Burkina Faso V. Balasubramanian, Ph.D .• agronomist, Rwanda D.\1. Naik, Ph.D., agronomist, Zimbabwe Y.S. Chen, M.S., agronomist B.R. Ntare, Ph.D., plant breeder, Niger 142 -Left during the year R.K. Pandey, Ph.D., regional coordinator for S. Y.c. Ng, v1.Sc., tissue cuhuds! Southeast Asia, Philippines D.S.O. Osiru, Ph.D., I.:rop physiologist W.R. Root, Ph.D., soybean breeder/agronomist, Zaria J.A. Otoo, Ph.D., breeder/agronomist S.A. Shoyinka, Ph.D., cowpea breeder/pathologist, R.L. Theberge, Ph.D., pathologist Zaria A ..' 1. Varela, B.Sc., entomologist, BraziJ B.B. Singh, Ph.D., cowpea breeder 1.B. Suh, Ph.D., cowpea entomologist, Burkina Faso Africa-wide Biological Control Project E.E. Watt, Ph.D., cowpea breeder, Brazil H.R. Herren, Ph. D., entomologist and team leader K. Weingartner, Ph.D., food scientist/utilization D.O. Friese, Ph.D., entomologist/acarologist· W.O. Hammond. M.Sc., entomologist T. Haug, Ir., entomologist (FAO associate expert) Maize Research Program B. Loehr, Ph.D., entomologist Y. Efron,Ph.D., program director B, Megevand, Ing., entomologistlacarologist D.T. Akibo-Betts, Ph.D., entomologist, Zimbabwe P. l\'euenschwander, Ph.D., entomologist N.A. Bosque-Perez, Ph.D., entomologist F. Schulthess, Ir.. entomologist (F AO associate expert) Z.T. Dabrowski, Ph.D., entomologist A. Wodageneh, Ph.D., entomologist/training officer (FAO expert) A. DiaHo, Ph.D., plant breeder, Burkina Faso 1.5. Yaninek, Ph_D., entomologist/acarologist 1.M. Fajemisin, Ph.D., pathologist/breeder T. [slam, Ph.D., plant breeder Applied Agricultural Research Project F.H. Khadr. Ph.D., plant breeder, Zaria S.K. Kim, Ph.D., plant breeder (RA V), Zaire M.H. Lee, Ph.D., plant breeder F.E. Brockman, Ph.D., agronomist and chief-of-party l.H. ;"·1areck, Ph.D., plant breeder C. Bartlett, Ph.D., agricultural economist L. T. Ogunremi, Ph. D., visiting agronomist C.B. Buyyala, farm manager V.O. Parkinson, Ph.D., pathologist* L.H. Camacho. Ph.D., plant breeder M. Rodriquez, Ph.D., agronomist and team leader, R.D. Hennessey, Ph.D., entomologist Burkina Faso K. Johnson, Ph.D., plant breeder c.Y. Tang, Ph.D., plant breeder, CIMMYT/IIT A G.F. Montalban, physical plant services officer C. The, Ph.D., visiting plant breeder O.A. Osiname. Ph.D .• agronomist S.J. Pandey, Ph.D., extension agronomist G.I. Servant, M.B.A., administrator Rice Research Program D. Shannon, Ph.D., agronomist 1 .A. Lowe, Ph.D., program director M. Veloso, physical plant services officer· A.O. Abifarin, Ph.D., IlTA liaison scientist at W.O. Vogel, Ph.D., agricultural economist WARDA, Liberia M.S. Alam, Ph.D., entomologist Cameroonian National Root Crops K. Alluri, Ph.D., agronomist/breeder Improvement Program (CNRCIP) R.C. Aquino, M.S., plant breeder H.l. Pfeiffer, Jr., agronomist and project leader V.T. John, Ph.D., pathologist J .A. Whyte, Ph, D., plant breeder T.M. Masajo, Ph.D., plant breeder E.P. Navasero, M.S., rice quality specialist National Cereals Research and Extension N.V. [\;guu, Ph.D., agronomist Project (NCRE), Cameroon M. Winslow, Ph.D., plant breeder, Onne E.A. Atayi, Ph.D., agricultural economist and M. Yamauchi, Ph.D., physiologist chief-of-party S.M.H. Zaman, Ph.D., IRRI liaison scientiSI* S. W. Almy, Ph.D., socioeconomist P. Ay, Ph.D., socioeconomist Root and Tuher O.P. Dangi, Ph.D., plant breeder L.T. Empig, Ph.D., plant breeder Improvement Program L. Everett, Ph.D., plant breeder S.K. Hahn, Ph.D., Fellow, lnst. Bio!., program D. Janakiram, Ph.D., plant breeder director and plant breeder l. Kikafunda-Twine, Ph.D., agronomist D. McHugh, M.S., extension economist A.M. Almazan, Ph.D., biochemist 'food technologist J.A, Poku, Ph.D., agronomist M.N. Alvarez, Ph.D., plant breeder, Rwanda M.R. Rao, Ph.D., agronomist V.L. Asnani, Ph.D" plant breeder, Jamaica A.C. Roy, Ph.D., agronomist F.E. Caveness, Ph.D., nematologist H. Talleyrand, Ph.D., agronomist J.H.M. Henderson, Ph.D., visiting crop physiologist* S. Welch, B.S., administrative officer K.M. Lema, Ph.D., entomologist • Ldt during the year 143 International Cooperation and Physical Plant Services Training Program J.G.H. Craig, director E.R. Terry, Ph.D .• program director E.O.A. Akintokun, research vehicles service officer D. Akintobi, M.Sc., assistant training officer A. Amrani, heavy equipment service officer E.F. Deganus, B.Sc., CAR, administrator A.K. Bhatnagar, assistant director, physical plant O.T. Edje, Ph.D., training officer for outreach services H. Gasser, Ph.D., principal program planning officer A.C. Butler, buildings and site service officer 0.1. Miller, Ph.D., training officer, Zaire O.O.A. Fawole, automotive service officer J .K. Mukiibi, Ph.D., regional training officer. Tan. P.J. Ghosh, scientific/electronics service officer zania P.G. Gualinetti, construction site engineering service officer F.O. Ogunyemi, FCCA, accountant D.W. Sirinayake, training officer J. Luko,,"ski, electrical service officer'" A.P. Uriyo, Ph.D., principal training officer H.G. Zingraf, assistant director, civil/mechanical'" Documentation, Information and Library Program S.M. Lawani, Ph.D" program director B. Bakare, A,A., head, conference and visitors' center R. Bitterli, M.S., writer/editor G.A, Cam bier , Lie" head, interpretation/translation M. Connolly, B. Agr. Sc., writer/editor D. T. De Grandsaigne, Lie., interpreter/translator· F.M, Gatmaitan, B.S., senior graphic designer G.O. Ibekwe, B.A., PGDL, principal librarian E. Molinero, Lie., interpreter/translator C. Moudachirou, Lie., interpreter/translator E.V. Oro, B,S., audiovisuals specialist J.O. Oyekan, B.S .• head, public affairs unit E. Tordeur, Lie" translator C. Vanhaelen, Lie" interpreter/translator Benin Research Station T.L Lawson, Ph.D., agroclimatologist and technical director O. Sidi, Ing. Agr., director of operations M. Versteeg, Ph.D., agronomist Genetic Resourcs Unit N.Q. Ng, Ph.D., head and plant geneticist A.E. Goti, Ph.D" plant scientist Virology Unit H.W. Rossel, [r., virologist G. Thottappilly, Ph,D., virologist Analytical Services Laboratory J ,L. Pleysier, Ph.D., head Biometrics P. Walker, M.A., biometrician Farm Management D.C. Couper, M.S., farm manager P.O. Austin, B,S., officer-in-charge, anne S.l. Claassen, M.S., assistant farm manager P. V, Hartley, B,S., farm management engineer 144 °Left durmg the year Collaborators, Research Fellows, and Research Scholars Resource aud Crop L. Van Craen (Belgium). State University of Ghent, Management Program Belgium Collaborators Grain Legume Scientists from National Programs in Africa Improvement Program Researcb Fellows Collaborators A. Diop (Senegal), Oregon State University. U.S.A. c. Amatobi, Institute of Agricultural Research, R. Ernest (West Germany), University of Hoheinheim, Samaru, Nigeria \V. Germany H. Diwa. Borno St, University of California, Program, Borno, Nigeria Davis, U.S.A. A.M. Emechebe, Institute of Agricultural Research, I.A. ldowu (Nigeria), Technical University of Berlin, Samaru, Nigeria W. Germany M.1. Ezueh, National Cereals Research Institute, N.O. Iwuafor (Nigeria), Ahmadu Bello University, Badeggi, Nigeria Zaria, Nigeria C.A. Fatokun, Department of Agronomy, University of F.R. Kuhne (West Germany), University of Ibadan, Nigeria Hoheinheim, W. Germany I. Fawole, Department of Agricultural Biology, Univer­ G. Ley (Tanzania), University of Aberdeen, U.K. sity oflbadan, Nigeria H.J. Lutzeyer (West Germany), University of C. Harkness, Kano Agricultural Development Project, Hoheinheim, W. Germany Kano, Nigeria H.F. Mahoo (Tanzania), Sokoine University of C. Hodgson, Department of Entomology, Wye College, Agriculture, Tanzania London A.G. Maul (West Germany), University of Hoheinheim, A. librin. Bida Agricultural Development Project, W. Germany Bida, Nigeria S.B. Mebrahtu (Ethiopia), South Dakota State O. Leleji, Institute of Agricultural Research, Zaria, University, U.S.A. Nigeria N. Okoronkwo (Nigeria), Catholic University, Louvain· L. Monti, Cattedra Di Genetica Agraria, UniversiUt !a-Neuve, Belgium Degli Studi di ~apoli, Italy M.A. Olagoke (Nigeria), University of Nigeria. Nsukka L. Murdock, Department of Entomology, Purdue K. Parker (U.S.A.), Princeton Uni .... ersity. U.S.A. University. West Lafayette, Indiana, U.S.A. O. Salau (Nigeria), University of Ibadan, I'igeria S. Nielsen. Department of Food Science, Purdue D.E. Siaw (Ghana), University of Ibadan, Nigeria University, West Lafayette, Indiana, U.S.A. M.K. Smith (Nigeria), University of Ibadan, Nigeria O.A. Ojomo, Oyo North Agricultural Development S. Zziwa (Uganda), University of Ife, Nigeria Project, Oyo, Nigeria E.Okoro, Imo State Agricultural Development Proj­ Research Scholars ect, Owerri, Nigeria J. Arthur (Ghana), University of Ghana, Legan P. Perrino, Plant Germplasm Institute, Bari, Italy N.O. Asonibare (Nigeria), Catholic Univer­ R. Shade, Department of Entomology, Purdue sity, Louvain-la-Neuve, Belgium University, West Lafayette, Indiana, U.S.A. E. Asselman (Belgium), Catholic L1niversity, Louvain­ la-Neuve, Belgium Research Fellows B. Kamara (Sierra Leone), Njala University. Sierra H. Adu-Dapaah (Ghana), University of lbadan, Nigeria Leone B. Asafo-Adjei (Ghana), University of Minnesota, c'M. Mayona (Tanzania), Sokoine University of U.S.A. Agriculture, Tanzania G. Gumisiriza (Uganda), Wye College, University of P. Mtakwa (Tanzania), Sokoine University of London Agriculture, Tanzania K. McGinnis (Canada), L'niversity of Guelph, Canada O. Olukunle (Nigeria). University of Nigeria. Nsukka S. Oghiakhe (Nigeria), University of Lagos, Nigeria G .0. Oyediran (Nigeria), University of Ife, Nigeria D.B. Oke (Nigeria), University of Ibadan, Nigeria F. Pietan (Belgium), University of Gembloux, Belgium G.O. Olatunde (Nigeria), University of lbadan, Nigeria F.K. Salako (Nigeria). University of Nigeria, Nsukka M. Owusu-Akyaw (Ghana), University of Science and 145 Technology, Ghana M.A. Choudhury, Regional Upland Rice Research 1. Roberts (Sierra Leone), Wye College, London Station, West Africa Rice Development Association (WARDA), Bouake, Ivory Coast Research Scholars C.M.M. Chewe, Luapu!a Regional Research Station, Mansa, Zambia J. Afun (Ghana). Wye College, U.K. H.M. Ching'ang'a, Ministry of Agriculture, Tanzania E.S. Akpan (Nigeria), Ahmadu Bello University, Zaria, A. Coly, Regional Irrigated Rice Research Station, Nigeria West Africa Rice Development Association M. Damme (Belgium), State University of Ghent, (WARDA), S1. Louis, Senegal Belgium H.M. Coulibaly, Ministere d'Agriculture, Institut M. Lumbelongo (Zaire), University of Ibadan, Nigeria d'Economie Rurale, Division de la Recherche M. Mapesa (Zaire), Catholic University, Louvain-la­ Agronomique, Bamako, Mali Neuve, Belgium S. Dake, Ministry of Social Development, Ilesha, F.A. Myaka (Tanzania), Wye College, U.K. Nigeria R. Noameshi-Afiavi (Togo), University of Ibadan, R.C. Dekukl1, Nyankpala Agricultural Experiment Nigeria Station, Tamale, Ghana C.P. Paul (Sri Lanka), University of Ibadan, Nigeria N.H. Dhere, Agricultural Research Institute, Mogadisho, Somalia Maize Research Program S. Dogbe, Departement de la Recherche Agricole (SRA), Lome, Togo Collaborators S.O. Fagade. National Cereals Research Institute Maize Scientists from National Programs in Africa (NCRI), Badeggi, Nigeria A. Faye, Centre de Recherches Agricoles de Djibelor, Research Fellows Zinguinchor, Senegal K. Goti, Institut de Savannes (IDESSA)-CV, Bouake, J .A. Durojaiye (Nigeria), University of Ibadan, Nigeria Ivory Coast J. P.c. Koroma (Sierra Leone), University of London E.D. Imolehin, National Cereals Research Institute E.N. Obazee (Nigeria), University of lbadan, Nigeria (NCRI), Badeggi, Nigeria F. Jeutong, Institut de la Recherche Agronomique Research Scholars (IRA), Dschang, Cameroon Y.A. Akintunde (Nigeria), University of Ibadan, A. Joshua, National Seed Service (NSS), Ibadan, Nigeria Nigeria M. Swerts (Belgium), Catholic University, Louvain-la­ Z. Kabiro, ISABU/SEMS-IMBO, Bujumbura, Burundi Neuve, Belgium A.N. Kihupi, Tanzania Agricultural Research Organization (TARO), Sokoine University of Agriculture, Morogoro, Tanzania Rice Research Program A.E.A. Lebo, Food Crops Division, Ministry of Collaborators Agriculture, Cross Rivers. State, Nigeria M.A. Mansaray, Rice Research Station, Rokupr, Sierra M. Abu, Rice Research Station, Rokupr, Sierra Leone Leone O.A. Adenola, National Accelerated Food Production I.M. Mharapara, Chiredzi Research Station, Chiredzi Program (NAFPP), Moor Plantation, lbadan, Zimbabwe Nigeria K.M. Miezan, Regional Upland Rice Research Station, J. Aho, Natitingou, Benin West Africa Rice Development Association (WAR­ E.O. Ajayi, National Cereals Research Institute DA), Bouake, Ivory Coast (NCR[), Badeggi, Nigeria I. Miranda, Ministere du Developpement Rural, Guinea A.T. Akpan, Food Crops Division, Ministry of Bissau Agriculture, Cross Rivers State, Nigeria J.S. l"anda, Federal Agricultural Coordinating Unit M.O. Aluko, Plant Quarantine Service, Moor Planta­ (FAClJ), Benin City, Nigeria tion, Ibadan, Nigeria J.J. Njokah, Western Kenya Scheme, Kisumu, Kenya A.c. Amaral, Instituto Nacional de lnvestigacao N.A. Nyanguile, Programme National du Riz (PNR), Agronomica de Mozambique (INIA), Mavalane­ Bumba, Kinshasa, Zaire Maputo, Mozambique W. Nzakimuena-Wete, National Rice Program, Kin- K.A. A},otade, National Cereals Research Institute shasa. Zaire (NCRI), Badeggi, Nigeria Y.I. Dh, Ghana-Korea Saemul Farm, Ghana A. Bizimana, Project DER VA M, Mutara, Rwanda A.L. Papastavrou, Kpong Farm, KpQng, Ghana A. Chaseta, Lifuwu Rice Research Station, Salima, K.G. PilIai, Sokoine University of Agriculture, Malawi Morogoro, Tanzania R.C. Chaudhary, Federal Agricultural Coordinating J. Ravatomanga, Departement de Recherches Unit, Kaduna, Nigeria Agronomiques, Antananarivo, Malagasy Republic 146 P. Reckhaus, German Agency for Technical Coopera­ C. Hodgson, Wye College, London tion (GTZ), Niamey, Niger A.M. Hoy, University of California, Berkeley, U.S.A. Z. Russom, Institute of Agricultural Research, Univer­ A. Joshua, National Seed Service, Ibadan, l\igeria sity of Port Harcourt, Nigeria D.N. Kalabare, Shell (CDPN) Farm Agbarho, Warri, M, Sie, Centre d'Experimentation du Riz et des Nigeria Cultures Irrigees (CERCI), Bobo-DiouJasso, Burkina H, Kronsteiner, Firma Dieringer, Vienna, Austria Faso N.B. Lutaladio, PRONAM, M'Vuazi, Zaire N_ Souleymane, Centre d'Experimentation du Riz et des R.H. Markham, Commonwealth Institute of Biological Cultures lrrigees (CERCI), Bobo-Dioulasso, Burkina Control, Nairobi, Kenya Faso H. Maraite, Universite Catholique de Louvain, Belgium F. Sumo, Central Agricultural Research Institute F. Martin, Tropical Agriculture Research Station, (CARl), Suakoko, Monrovia, Liberia Mayaguez, Puerto Rico J. Tchatchoua, Institut de la Recherche Agronomique, L.C.E. Pannunzio, EMBRAPA, Brasilia, Brazil Dschang, Cameroon J. Noyes, British Museum, London F. Tsekakele, Centre de Recherches Agronomiques de F.J. Novak, International Atomic Energy Agency, Loudima, Brazzaville, Congo Vienna, Austria E.C. lJbani, Farm Manager, lmo State Agricultural N. Nsumbu, Institut Facultaire des Sciences Development Area Project (ISADAP), Nigeria Agronomiques, Yangambi, Haut-Zaire, Zaire M,N. Ukwungwu, National Cereals Research Institute D. O'Donnell, Commonwealth Institute for Biological (NCR!), Badeggi, Nigeria Control, London S. Wanki, Upper Noun Valley Development Authority O.A. Ojomo, Oyo North Agricultural Development (UNVDA), Ndop, Cameroon Project, Shaki, Nigeria B.D. Wudiri, National Cereals Research Institute J .E. Okeke, National Root Crops Research Institute, (NCRI), Badeggi, Nigeria Umudike, Nigeria G.W. 0100, ICIPE, Nairobi, Kenya Research Fellow F. Quak, The Research Institute for Plant Protection, Wageningen, The Netherlands A.S, Kumwenda (Malawi), Wye College, U.K. U. Regev, University of Negev, Israel M, W, SabeJis, University of Leiden, The Netherlands Research Scholar M,E. Smalley, Training Coordinator. ICIPE, Nairobi, M.J, Tits (Belgium), Catholic University, Louvain-la­ Kenya Neuve, Belgium J. Van Alphen, University of Leiden, The Netherlands L.D. Wickham, Department of Crop Science, Univer­ Root and Tuber sity of the West Indies, St. Augustine, Trinidad D.J. Williams, Commonwealth Institute of En- Improvement Program tomology, London Collaborators Research Fellows A. Aguigua (Cameroon), University of Ibadan, Nigeria A. Ajlbola, Department of Agricultural Engineering, A. Chalabesa (Zambia), Wye College, U.K. University of He, Nigeria E. Cudjoe (Ghana), Wye College, U,K. J. Baumgaertner, Federal Institute of Technology, C.E. Gyansa-Ameyaw (Ghana), University of Ghana, Zurich, Switzerland Legon A. BeUotti, Centro Internacional de Agricultura B.M.S. Hemeng (Ghana), University of Science and Tropical, Cali, Colombia Technology, Kumasi, Ghana J, Boussienguet, Laboratoire de Zoologie et de Lutte M. Makame (Tanzania), University of lbadan, Nigeria Biologique, Libreville, Gabon W. Masamba (Zaire), National University of Zaire J.P.J. easier, Laboratory of Applied Carbohydrate J.M. Ngeve (Cameroon), University of Maryland, and Cereal Chemistry, Catholic University, Louvain­ U.S.A. la-Neuve, Belgium F,J. Senkondo (Tanzania), Wye College, U.K. K.E. Cockshull, Glasshouse Crops Research Institute, J.A. Tumateh (Cameroon), University of Ibadan, Littlehampton, U,K. G. Nigeria De Moraes, EMBRAPA, Brazil J, Victor (India), University of Benin, Benin City, L.K. Djokoto, Volta Region Agricultural Development Nigeria Project (VORADEP), Ho, Ghana W. Walangululu (Zaire), Institut Facultaire des Sciences T.U. Ferguson, The University of the West Indies, St. Augustine, Trinidad, West Indies Agmnomiques, Yangambi, Zaire C.H.W. Flechtmann, Universidade de Piracicaba, Research Scholars Brazil A.P. Gutierrez, University of California, Berkeley, M.A. Animashaun(Nigeria), WyeCollege, U.K. U.S.A. O. Fadiya(Nigeria), The Pol)1echnic, Ibadan, Nigeria 147 A. Kaitibi (Sierra Leone), University of Ibadan. Nigeria A. Laveleh (Liberia), University of Ibadan, l\igeria S.J. Mugalu (Uganda), Wye College, U.K. R. Ndibaza (Tanzania), University of Ibadan, Nigeria C.O. P'Obwoya (Uganda), University of Ibadan, l\'igeria M. Simwambana (Zambia), University of the West Indies, Trinidad, West Indies M. Tchuanyo (Cameroon), Imperial College, London Genetic Resources Unit Collaborators M. Horn, The International Board for Plant Genetic Resources, Burkina Faso L ~onti. University of Napoli, Italy P. Perrino, Plant Germplasm Institute, Bari, Italy E. Carnovale, Istituto Nazionale della Nutrizione, Rome, Italy C. de Pace, Istituto di Biologia Agraria, Viterbo, Italy Research Fellow F. Begemann (W. Germany), Technical University of Munich, West Germany Farm Management Research Scholars G. Diwakar (India) A. Pinney (U.K.), Reading University, U.K. L Hamud, Somali Government 148 Publications Resource and Crop Management Program Akobundu, 1.0. 1986. Weeds and their control. In:lntroduction (0 Tropical Agriculture edited by A. Youdouwei, F .O.C. Ezedinma and O.C. Onazi, London, Longmans. pp. 160-179. Akobundu. 1.0. 1986. Importance of proper legislation and recommendation for pesticides in developing countries. Champs du Mande, Special Issue l\o. 4, pp. 51-53. Akobundu, 1.0. and J. Poku. 1986. Weed management. In: The Wetlands and Rice in sub·Saharan Africa edited by A.S.R. Juoand J.A. Lowe. Ibadan, lITA, pp. 175-182. Arora, Y., K. Mulongoy and A.S.R. Juo. 1986. Nitrification and mineralization potentials in a limed Ultisol in the humid tropics. Plant and Soil 92: ] 53-157. Baiasubramanian, V. and L. Sekayange.1986. Biological soil fertility management in African highlands with examples from Rwanda. Transactions of the 13th Congress of the International Society jor Soil Science, vol. 3, pp. 675-676. Banarjee, N., D. Vuylsteke and E.A.L. de Langhe. 1986. Meristem tip culture of Musa: histomorphological studies of shoot bud proliferation. In: Plant Tissue Culture and Its Agricultural Applications, edited by L.A. Withers and P .G. Alderson, London, Butterworths, pp. 139-147. Couper, D.C., R. Lal and S.L. Claassen. 1986. Agronomic problems with large scale mechan· ized land development and farming in West Africa. In: Land Clearing and Development in the Tropics edited by R. Lal, P.A. Sanchez and R. W. Cummings. Rotterdam, A. Balkema, pp. 149-158. Ezumah, H.C. 1986. Introducing the root crops based cropping systems research network in Nigeria. West African Far­ ming Systems Research Network Builetin 1(2): 12-13. Gunneweg, H.A.M.I., A. Evers and A. Huizing. 1986. A model to assess proposed procedures for water control., ap­ plication and results for two small inland valleys. In: The Wetlands and Rice in sub-Saharan Africa edited by A.S.R. Juoand'J.A. Lowe.lbadan, UTA, PD. 87-94. Hulugalle, N.R. and R. La!. 1986. Root growth of soybean and cowpea on a hydromorphic toposequence in western Nigeria. Plam and Soif91: 195-208. Hulugalle, N.R. and R. Lal. 1986. Soil water balance of interc ropped maize and cowpea grown in a tropical hydromor­ phic soil in western Nigeria. Agronomy Journaf78: 86-90. Hulugalle, N.R., R. Lal and C.H.H. ter Kuile. 1986. Amelioration of soil physical properties by mucuna following mechanized land clearing of a tropical rainforest. Soil Science 141: 219-224. Hulugalle, N.R. and R. Lal. 1986. Root growth of maize in a compacted gravelly tropical Alfisol as affected by rotation with a woody perennial. Field Crops Research. 13: 33-44. Juo. A.S.R. and LA. Lowe (eds). 1986. The Wetiandsand Rice in sub-Saharan Africa. [badan, lITA, 320 pp. Kang, B. T. 1986. Cropping systems and soil fertility management in the humid and sub-humid tropics with special reference to West Africa. In: Management oj Nitrogen and Phosphorus Ferrilizers in sub-Saharan Africa edited by A. U. Mokwunye and P.L.G. Vlek. Dordrecht, Martinus Nijhoff, pp. 83-94. Kang, B. T. and A.S.R. Juo. 1986. Effect of forest dearing on soil chemical properties and crop performance. In: Land Ciearing and Development in the Tropics edited by R. Lal, P.A. Sanchez and R.W. Cummings, Rotterdam, Balkema, pp.383-394. Kayombo, B. and R. Lal. 1986. Effects of soil compaction by rolling on soil structure and development of maize in no­ till and ploughing systems in a tropical Alfisol, Soil & Tillage Research 7: 117-135. 149 Kayombo, B.R., R. La] and G.c. ~rema. 1986. Influence of traffic induced compaction on tropical Alfisol. 1. soil physical properties. Journal of the Science ofF ood & Agriculture 37: 969-978. Kosaki. T. and A.S.R. Juo. 1986. Iron toxicity office in inland valleys: a case from Nigeria. In: The Wetlands and Rice in sub-Saharan Africa edited by A.S.R. Juo and J.A. Lowe. Ibadan, lITA, pp. 167-174. Kyuma, K., T. Kosaki and A.S.R. Juo. 1986. Evaluation of the fertility of the soils. In; The Wetlands and Rice in sub­ Saharan Africa edited by A.S.R. Juo and J.A. Lowe.lbadan, IITA, pp. 43-58. Lal, R. 1986. Effects of eight tillage treatments on a tropical Alfisol. I. Maize growth and yield. Journal of the Science of Food and Agriculture 37: 1073-1082. Lal, R. 1986. Effects of 6 years of continuous cultivation by no-till or puddling systems on soil properties and rice yield of a clayey soil. Soil & Tillage Research 8: 181-200. Lal, R., P.A. Sanchez and R. W. Cummings, Jr. (eds.). 1986. Land Clearing and Development in the Tropics. Rotter­ dam, A. Balkema, 450p. Lal, R. 1986. Conversion of tropical rainforest: agronomic potential and ecological consequences. Advances in Agronomy 39: 173-263. Lal, R. 1986. Soil surface management in the tropics for mtensive landuse and high and sus­ tained production. Advances in Soil Science 5: 1-105. Lal. R. 1986. No-tillage and minimum tillage systems to alleviate soil related constraints in the tropics. In: No-tillage and Minimum Tillage Systems edited by M.A. Sprague and G.B. Triplett. New York, John Wiley & Sons, pp. 261-317. Lal. R. 1986. Different methods of land clearing for agricultural purposes in the tropics. In: Land Clearing and De\!elopment in The Tropics. edited by R. Lal, P.A. Sanchez, and R.W. Cummings Jr. Rotterdam, A. Balkema, pp. 55-68. Lal, R. 1986. Deforestation and soil erosion. In; Land Clearing and Development in the Tropics edited by R. Lai, P.A. Sanchez and R. W. Cummings, Jr. Rotterdam. A. Balkema. pp. 299-316. Moormann, F.R. and A.S.R. Juo. 1986. Present land use and cropping systems in Africa. In: The Wetlands and Rice in sub-Saharan Africa edited by A.S.R. Juo and J,A. Lowe. lbadan. IITA. pp. 187-194. Muiongoy, K. 1986. Potential of Sesbania rostrata (Brem.) as a nitrogen source in alley crop­ ping systems. Biological Agriculture and Horticulture 3: 341-346. Mulongoy, K. 1986. Microbial biomass and maize nitrogen uptake under a Psophocarpus polustris live mulch grown on a tropical Alfisol. Soil Biology and Biochemistry 18: 395-398. Muiongoy, K. and A. Ayanaba. 1986. Dynamics of the population sizes of cowpea and soybean rhizobia at three loca­ tions in West Africa. Mircen Journal of Applied Alicrobiology and Biotechnology 2: 301-308. Mutsaers. H.J.W., M.e. Palada and W.A. Vogel. 1986. UTA's on-farm/farming systems research program. West African Farming Systems Research Network Bulletin No. I, pp. 4-5. Mutsaers, H.J .W. 1986. On-farm research models and their implementation in some African countries. West African Farming Systems Research Network Bulletin No.2, pp. 22-26, Navasero, N.C., R.C Bautista and R.M. Lantin. 1986. Tools and implements for rice farming. In: The Wetlands and Rice in sub-Saharan Africa edited by A.S.R. Juo and J .A. Lowe. lbadan. IITA, pp. 239-247_ Ogunremi, L.T., R. Lal and o. Babalola. 1986. Effects of tillage and seeding methods on soil physical properties and yield of upland rice for an Ultisol in southeast Nigeria. Soil & TiiJage Research 6: 305-324. Ogunremi, L.T., R. Lal and O. Babalola. 1986. Effects of tillage methods and water regimes on soil properties and yield of lowland rice from sandy soil in south-west Nigeria. Soil & Tillage Research 6: 223-234. 150 Opara-Nadi, O.A., R. Lal and B.S. Ghuman. 1986. Effects of land -clearing methods on soil physical and hydrological properties in south-western Nigeria. In: Land Clearing and Development in the Tropics edited by R. La], P.A. Sanchez and R.W. Cummings, Jr. Rotterdam, A. Balkema, pp 215-225. Osiname, O.A. and B. T. Kang. 1986. The effect of potassium fertilization on maize yield and calcium, magnesium and potassium status in an Oxic Paleustalf in south-western Nigeria. Potash Review 5 (9): 1·6. Palada, M.C., W.O. Vogel and H.J.W. Mutsaers. 1986. On-farm testing of improved technologies in south-western Nigeria: The l1TA experience. Proceedings 6th Annual Farming Systems Research and Extension Symposium, KSU, Manhattan, Kansas, USA. pp. 383-419. Sanginga, N., K. Mulongoy and A. Ayanaba. 1986. Inoculation of Leucaena leucocephala (Lam.) de Wit with Rhizobium and its nitrogen contribution to a subsequent maize crop. Biological Agriculture and Horticulture 3: 347-352. Sobulo, R.A. and O.A. Osiname. 1986. Soil properties and crop yields under continuous cultivation with different management systems. In: Land Clearing and DeveJopment in the Tropics edited by R. Lai, P. Sanchez and R. Cum­ mings. Rotterdam, A, Balkema, pp. 363-370. Spencer, D.S.C. 1986. Agricultural research: iessons of the past, strategies for the future, In: Strategiesjor African Development edited by R.G, Berg and J ,So Whitaker, University of California Press, pp. 215-241. Utulu, S.N., I.O. Akobundu and A,A.A. Fayemi. 1986. Persistence and downward movement of some selected her­ bicides in the humid and sub-humid tropics. Crop Protection 5: 129-136, Vuylsteke, D. and a.F, Wilson. 1986. Genetic stability of in vitro propagated plantain (Musa cv. AAB). In: Sixth Inter­ national Congress on Plant Tissue and Cell Culture edited by D.A. Sumers et aI., Minneapolis, University of Min· nesota, p. 258. (Abstract only). Wilson, a,F., B.T. Kang and K. Muiongoy. 1986. Alley cropping: trees as sources of green-manure and mulch in the tropics. BiologicaJ Agriculture and Horticulture 3: 251-267. Wilson, a.F. and R. LaJ. 1986. New concepts for post-dearing land management in the tropics, In: Land Clearing and Development in the Tropics edited by R. Lal, P. Sanchez and R. Cummings. Rotterdam, A. Balkema. pp.378-381. Yamoah, C.F" A.A. Agboola and K. Mulongoy. 1986. Decomposition, nitrogen release and weed control by prunings of selected alley cropping shrubs. AgroJorestry Systems 4(3): 239-246. Yamoah, C.F., A.A. Agboola, and G.F. Wilson. 1986. Nutrient contribution and maize performance in alley cropping systems. Agroforeslry Systems 4(3): 247-254, Grain Legume Improvement Program Jackai, L.E.N. and R.A. Daoust. 1986. Insect pests of cowpeas. Annual Review of Entomology 31: 95·119. Jackai, L.E.N. and S.R. Singh, 1986. New foliar insecticides for the control of cowpea pests. in: Proceedings of 0 British Crop Protection Conference held at Brighton Metropole". Pests and Diseases. Surrey, British Crop Protection Council, vol. 2, pp. 761-768. Mai.e Research Program Awoyemi, 0" K.A. Ayotade, J.M, Fajemisin, O.A, Adenola, and U. Mokwunyen. 1986, Meeting the challenges of cereals self-sufficiency in Nigeria with special reference to rice, maize and sorghum. In: Proceedings oj the 4th Joint NAFPP/National Agricultural Development Committee edited by O.A. Adenola, B.A. Okobaroh and La. Fatoba. Ibadan, National Rice/Maize Centre (NAFPP), pp. 13-66. 151 Fajemisin. J.M. 1986. Maize diseases in Africa and their role in the varietal improvement process. In: To Feed Ourselves: Proceedings of the First Eastern, Central and Southern Africa Regional Workshop edited by B. Gelaw. Mexico. CrMMYT. Giskin. M. and Y. Efron. 1986. Planting date and foli';ir fertilization of corn grown for silage and grain under limited moisture. Agronomy Journal 78: 426-429. Kim, S.K., Y. Efron, J. Fajemisin, L.T. Ogunremi, M.H. Lee, I.E. Eneh, O.A. Adenols. and A. Joshua. 1986. A review of the Pilot Hybrid Maize Production Programme in Nigeria. In: Proceedings of the 4th Joint NAFPPINationai Agricultural Development Committee edited by O.A. Adenola. B.A. Okobar0h and I.O. Fatoba. Ibadan, National Rice/Maize Centre (NAFPP), pp. 175-206. Rice Research Program Alam, M.S. and Y. Efron. 1986. Resistance of rice to stalk-eyed fly, Diopsis macrophlhalma Dalman. International Rice Commission Newletter35(1): 40-45. Alam, M.S. and T. M. :\1asajo. 1986. Resistance of rice varieties to gall midge, Orseoiia oryziora Harris and Gagne. An­ nual Plant Resistance to Insects Newsleuer 12: 53-54. Alluri, K. 1986. Screening rice ,,·arieties in acid upland soils. In: Progress in Upland Rice Research. Los Banos, IRRI, pp. 263·270. Allnri, K., T.M. Masajo, Kaung Zan, V.T. John and M.S. Alam. 1986. Upland rice improvement in humid and sub­ humid tropics of West Africa. In: Progress in Upland Rice Research. Los Banos, IRRI, pp. 235·244. Alluri, K., S.M..H. Zaman, Kaung Zan and D.V. Seshu. 198<). Cooperation between Afd~a, Asia and Latin A.merica: the International Rice Testing Program. In: The Wetlands and Rice in sub-Saharan Africa edited by A.S.R. Juo and J.A. Lowe. Ibadan. UTA, PP. 133-138. John, V. T., M.S. Alam and G. Thottappilly. 1986. Diseases and insect pests of wetland rice in tropical Africa. In: The Wetlands and Rice in sub-Saharan Africa edited by A.S.R, Juo and J .A. Lowe. lbadan, lITA , pp. 141-150. Lawson, T.L. and K. Alluri. 1986. Upland rice environments in Nigeria and the fitness of improved technologies In: Progress in Upland Rice Research. Los Banos, IRRI, pp. 35-49. Masajo, T.M., K. Alluri, A.O. Abifarin and D. Janakiram. Breeding for high and stable yields in Africa. In: The Wetlands and Rice in sub-Saharan Africa edited by A.S.R. Juo and J.A. Lowe. Ibadan, IITA, pp. 107-114. Root and Tuher Improvement Program Egunjobi, O.A., P,T. Akonde and F.E. Caveness. 1986. Interaction between Pratyfenchws sefaensis, Me{oidogyne javanica and Rotyfenchulus remformis in sole and mixed crops of maize and cowpea. Revue de Nematologie 9: 61-70. Lohr, B. and H.R. Herren. 1986. lnsekten gegen Insekten: Biologische SChadlingsbekampfung gegen die Maniokschmierlaus in Afrika. Entw;cklung & Liindlicher Raum 3/86: 29~33. Neuenschwander, P., F. Schulthess and E. Madojemu. 1986. Experimental evaluation of the efficiency of Epidinocar­ sis lopezi, a parasitoid introduced into Africa against the cassava mealybug Phenacoccus manihoti. Entomologia Ex­ perimenfaJis et Appiica/(J 42: 133·138. Neuenschwander, P. and E. Madojemu. 1986. Mortality of the cassava mealybug Phenacoccus manihoti MaL-Ferr. (Hom., Pseudococcidae) associated with an attack by Epidinocarsis {opezi (Hym., Encyrtidae). Mitteilungen der Schweizerischen Entomologischen Geselischaft 59: 57-62. Okoli, 0.0., S.K. Hahn. J.A. Otoo and I. Eleje. 1986. Potential contribution of root crops to the national goal of self­ sufficiency - a revlsed natioinal plan. In: Proceedings of the 4th Joint /'t.'AFPPI National Agricultural Development Committee edited by O.A. Adenola, B.A. Okobaroh and 1.0. Fatoba. Ibadan, National Rice/Maize Centre (NAFPP), pp.67·75. 152 Virology Unit Atiri, G.!., D.A. Enobakhare, and G. Thottappilly. 1986. The importance of colonizing and noncolonizing aphid vec­ tors in the spread of cowpea aphid-borne mosaic virus. Crop Protection 5(6): 406-410. John, V.T., M.S. Alarn and G. Thottappilly. 1986. Diseases and pests of wetland rice in Africa. In: The Wetlands and Rice in sub-Saharan Africa edited by A.S.R. Juo and J.A. Lowe. Ibadan, UTA, pp. 141-150. Documentation, Information, and Library Program Babaleye, T. 1986. New cropping system reveaL'i promise for low-input farmers. Ceres (FAD Review) 19(109): 6-7. Babaleye, T. 1986. Wetlands: great potential for food production. International Agricultural Devefopment 6(3): 15-16. Babaleye, T. 1986. Maize: tackling a disease that means low yields. International Agricultural Development 6(4): 17. Babaleye, T. 1986. Agrometeorology. AJrican Farming and Food Processing, September/October, p. 63. Babaleye, T. 1986. Using the weather to grow more food. International Agricultural Development 6(6): 6-7. Fulier, \V.H., R. Bitterli and M. Unger. 1985. Attenuation of paperpulp mill constituents by clay soil. Arizona Agricultural Experiment Station Research Report No. 287. Tucson, Arizona, U.S.A. Ibekwe, G.O. 1986. Le mais: publications en langue francaise disponibles a fa bibliotheque de l'IlTA.Ibadan, IITA, 244p. Lawani, S.M. 1986. Some bibliometric correlates of quality in scientific research. Scientometrics 9(112): 13-25. Lawani, S.M. 1986. Africa's Quiet revolution. Standard Chartered Review. October, pp. 2-7. Oro, E. V. 1986. Basic course in photography, liTA , Ibadan. 40p. Russell, N. 1986. The International Institute of TropicaJ Agriculture. Topic No. 159, pp. 9-16. Genetic Resources Unit Ng, N.Q. and R. Marecha!. 1985. Cowpea taxonomy, origin and germplasm. In: COl1pea Research. Production and Utilization edited by S.R. Singh and K.O. Rachie. London, John Wiley & Sons, pp. 11-21. Analytical Services Laboratory Pleysier, J.L., J. Janssens and A. Cremers. 1986. A clay suspension stability end point titration method for measuring CEC of soils. Soil Science Sociely of A merica Journal 50: 887-891. Administration Okigbo. B.N. 1985. The administration of science and technology. In: Nigerian Public Administration 1960-1980: Perspectives and Prospecls edited by L. Adamolekun. Ibadan, Heinemann, pp. 231-245. Okigbo, B. N. 1985. Strategies in research on improved farming systems to Jacmtate adoption and management by the NigerianJarmer. Borin, ARMTI. 52 p. Okigbo. B.N. 1986. The African condition and the need for urgent and appropriate action. In: Proceedings of the African Agricultural Development Conference edited by Y. T. Moses. Pomona, California State Polytechnic Universi­ ty, pp. 25·39. Okigbo, B.N. 1986. Future education needs of Africa. In: Proceedings of the African Agriculture Development Con­ Jerenceedited by Y.T. Moses, Pomona, California State Polytechnic University, p. 174. 153 Okigbo, B.N. 1986. Broadening the food base in Africa: the potential of traditional food plants. Food and Nutrition 12(1): 4-17. Okigbo, B.N. 1986. Welcome Address to the World Cowpea Research Conference. Tropical Grain Legume Bulletin 32: 5-9. Okigbo, B.N. 1986. "Foreword" to Understanding Africa's Rural Households and Farming Systems edited by J.L. Maack. Boulder, Westview Press, ix-xiii. 154