Cowpea Research

at IITA :: GLiP Research Monograph No.1

Grain Legume Improvement Program International Institute of Tropical Agriculture

PMB 5320, Oyo Road Ibadan, Nigeria

GLIP Research Monograph No.1

Cowpea Research at IITA

Contributors

S. R. Singh, L. E. N. Jackai, B. B. Singh, B. N. Ntare. H. W. Rossel, G. Thottappilly, N. Q. Ng. M. A. Hossain,

K. Cardwell, S. Padulosi and G. Myers

Grain Legume Improvement Program Illlematlonallnstitute of Tropical Agriculture

December 1989

About llTA

The goal o( the International Institute of Tropical Agriculture (lIT A) is to inaease the productivity of key food crops and to develop sustainable agri­cultural systems that can replace bush fallow, or s1ash-and-bum cultivation in thchurnidand subhumid ttopics. Crop improvement programs focus primar­ily on cassava, maize and cowpeas. Yams, soybean and plantain are also majorresearch concerns. Research findings are shared through international coopmWon programs which include training. information and germplasm exchange activities.

ITT A was founded in 1967. The Federal Government of Nigeria provided a land grant of 1.000 hectares at Ibadan, for a headquarters and experimental fann site. and the Rockefeller and Ford foundations provided fmancial support. lIT A is governed by an international Board of Trustees. The staff includes nearly 200 scientists and professional staff from about 40 countries, who work at the Ibadan campus and on substations and outreach programs in many countries of sub-Saharan Africa.

lIT A is one of 13 nonprofit. international agricultural research centers and programs suppcrted by the Consultative Group on International Agricultural Research (CGIAR). Established in 1971, CGIAR is an association of about 50 governments, intemationaland regional organizations and private founda­tions. The purpose of the research effort is 10 improve the quantity and quality of food production in developing counbies. The World Bank. the Food and Agriculture Organization of the United Nations (FAO) and the United Nations Development Programme (UNDP) are cosponsors of this effort.

C 1989 Intanational Institute of Tropical Agriculture

'J'El..BPHONE: (234~22) 400300400318 TELEX: 31159 or 31417 TROPIB NG CABU: TROPFOUND IKEJA

Preface

Introduction

Production

Constraints in production

Research at UTA

Research goals

Achievements ..

Impact

CONTENTS

Collaborative and contract research

References

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1

1

4

8

8

10

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17

19

Preface

Cowpea research at IITA began in 1970. During the past two decades, extensive world gennplasm of cowpea has been collected at lIT A. The gennplasm has been exploited to identify useful traits, most of which have been incorporated in the breeding program.

UTA cowpea research evolved originally from an approach of pyramiding genes for disease and insect resistance, in a monocrop situation, to developing cowpea in its agroecological context and prob­lems which must be solved within cowpea cropping systems.

The program now concentrates on development of:

1. Cowpeas that are well adapted to the cereal fanning systems of the African savannas and that meet the needs for grain and fodder. and

2. Insect resistance to post-flowering pests as part of liT A strategy for integrated pest management.

This publication describes briefly the advances made since the 19708 and the current status of the cowpea improvement program, which seeks to fulfil lIT A's general objective of promoting sustainable agricul­ture.

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S. R. Sing"

Director, Grain Legume

Improvement Program

Introduction

Cowpea, Vigna unguiculata (L.) Walp, also known as the black·eye pea or southern pea, is a protein· rich crop with 24% protein content (Bressani 1985). A major food legume in Africa, it is also extensively cultivated in the lowland tropics of Asia and Latin America. Cowpea in Africa is traditionally considered as a food legume of the poorest of the poor and is mostly cultivated by small·scale fanners as a subsistence crop. It is a secondary crop mainly in semi·arid ecologies, in association with millet, sorghum, maize, cassava and cotton. It is droughHoleraot and can be grown in poor soils. Cowpea is able to fIx nitrogen in the soil efficiently at around 30 to 70 kilograms per hectare (kg/ha) .

Unlike many other legumes, cowpea may be consumed at various stages ofits development: as green leaves, green pods, green peas and dry seeds, which is the most popular. Dry cowpea seeds take comparatively less time to cook. than many other food legumes, an important consideration in most developing countries where cooking fuel is scarce and expensive. In the mixed farming systems of the Sahelian regions, cowpea is the predominant legume and fonns an important source of human food and fodder for cattle.

Research conducted on cowpea over the years by the national programs and liT A has made cultivation of the crop more attractive to both small· and large·scale growers. New varieties with higher yield potential. a range of maturities. and resistance to some diseases and insect pests are being grown in larger areas and different ecological zones than before. In addition to the small·scale producers, a number of medium-to-Iarge-scale fanners are cultivating the crop often in rotation with cereals.

Production

Cowpea production has been estimated at about 2.3 million tons from 7.7 million hectares. However, these figures are considered to be underes­timates of the real production levels and total area cultivated, because cowpeas are grown as multipurpose subsistence crops on small fann holdings, and much of the small-scale production is neither quantified

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nor included in crop production statistics. Rachie (1985) has stated that real production levels may approach or exceed 2.5 million tons of dry seeds on about 9.0 million hectares. Even those figures fall shon of actual production because of increasing large-scale cultivation of early­and medium-maturing improved cowpea varieties in upland farming conditions as a monocrop and in rice fallows.

Currently more than 70% of world cowpea production is con­centrated in three countries: Nigeria, Brazil and Niger. Nigeria produces about 0.9 million tons annually on 4.0 million hectares, most of which is in the three northern states of Kano, Sokoto and Bomo. Brazil produces about 0.4 million tons on 1.7 million hectares, and Niger O. 3 million tons on about 1.1 million hectares. Other major producers in Africa include Benin, Botswana, Burldna Faso, Cameroon, Ghana, Kenya, Malawi, Mali, Mozambique, Senegal, Somalia, Tanzania, Togo and Uganda. In Asia, cowpeas are increasingly becoming part of the rural diet in Bangladesh, Bunna, India, Philippines, Sri Lanka and Thailand. lbis has led to increased local production. In Latin America. apart from Brazil. cowpea is an important food crop in Caribbean, El Salvador. Mexico, Nicaragua and Peru subregion, where considerable amounts are grown.

The dry grain yields of traditional varieties have been low. In Africa, yields are estimated at about 250 to 300 kilograms per hectare; in Asia and Latin America, about 400 to 500 kilograms per hectare; and in the USA, about 600 to 800 kilograms per hectare. The low yields in Africa, Asia and Latin America are generally attributed to poor crop husbandry, insect pests and diseases, drought and poor plant type. Cowpea harvested as green pods in the lowland humid tropics yields from 10 to 15 tons per hectare. In the Sahel, green fodder yields approach 30 to 40 tons or 3 to 4 tons of dry weight per hectare.

Agroecological zones

Six major agroecological zones are distinguished on the basis of rainfall and the following factors: (a) cropping systems, (b) production con­straints, (c) diversity of crop genotypes. and (d) how the crop is utilized in each particular region.

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ZONES

Sahel Dry savanna Moist savanna Transition zone Humid forest Mid-altitudes

RAlNPAlL (MM)

300-600 600-900 900-1300 1300-1600 1600-2500 500-1200

Cowpeas cultivated in these different zones vary a great deal, being influenced by the climatic conditions and cropping systems.

Sahel. Cowpea is the predominant legume in the cropping systems of the Sahel. Here it is consumed as green leaves, dried leaves. green peas, dry grain and fodder. After harvest, the dried plants are bundled and stored for use as fodder for cattle during the harsh dry weather period. Tradi­tional fann varieties are an indetcnninate. viny, spreading type with a growing period of up to 120 days. They are fast-growing, cover the soil surface and produce large quantities of biomass. In the Sahel millet is the main cereal; cowpea is cultivated in mixtures with millet.

Savanna. In the dry and moist savannas, cowpea is mostly intercropped with millet, sorghum and maize as a secondary crop after the cereal crop is established. Cowpea is cultivated mostly for dry grain and fodder. Fanners often plant an early-maturing cowpea for dry grain along with a cereal with the first rains. and later, after the cereal is established. the main cowpea crop is planted for both grain and fodder.

Humid Forest and Transition. In the lowland humid tropics in the bimodal rainfall areas, cowpea is planted in the second (shon rainfall) season, in fields previously established with a cereal or root crop. Cowpea in this region is cultivated mostly for dry grain and is also used to a limited extent as a green leafy vegetable. Early· to medium-maturing (60 to 70 days) varieties are preferred. Short, compact and upright varieties are considered most suitable.

In the forest zone, cowpeas have traditionally been grown on a trellis for green pods for household subsistence needs. The continuous rain and high humidity which prevails for 9 to 10 months of the year prevents fanners from growing cowpea for dry grain. In a few scattered niches. small smooth-seeded cowpeas are cultivated, but at a very low

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level. In humid tropics of Asia, cowpeas are cultivated in rice field fallows during the summer season.

Mid-Altitudes. In the regions with cool mid-altitudes, particularly in eastern Africa and southeastern Asia, cowpeas are mostly cultivated for dry grain in mixtures with cereals, or as a monocrop. These varieties tolerate cold and drought

Nigeria, on the north-south axis, has all the major agroecologi­cal zones (figure I), which has helped UTA in the development of cowpeas for the various cropping systems across the different zones.

Constraints in Production

The constraints in cowpea production vary to some extent according to agroecological lone. Insect pests, diseases, drought and heat can be considered as major constraints in those zones where cowpea is a predominant grain legume in the cropping system.

The mdjor insect pests in the different zones are:

• Sahel

• Savanna

• Humid Forest and Transition

• rvlid-altitudes

aphid, thrips, bruchid

aphid, thrips, Maruca pod borer, pod-sucking bugs, bruchid

aphid, thrips, Maruca pod borer, pod-sucking bugs, bruchid

aphid, bruchid

The major diseases and plant parasitic weeds in the different ecologies are:

• Sahel

• Savanna

bacterial blight, bacterial canker, Macrophomina ashy stem blight, cowpea aphid-borne mosaic virus, Striga

Septoria leaf spot, scab, web blight. brown blotch, bacterial blight, Cercospora leaf spot. Macrophomina ashy stem blight, cowpea mottle

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FIGURE 1. Vegetation map of Nigeria

P. Rep. of Benin

1250rrmliiigll_

IIliiJ Coastal ."amp •

• Forest

~ Forest savanna ~ (transition ~one)

IIIJIII] Guinea IIOvanna

~ Sudan savanna

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cameroon

N

t

• Humid Forest and Transition

• Mid-altitudes

virus, southern bean mosaic virus, cowpea yellow mosaic virus, cowpea aphid-borne mosaic virus, golden mosaic virus Striga, Alectra

brown blotch. anthracnose, web blight. Fusarium wilt, Cercospora leaf spot, bacterial pustule, bacterial blight, brown rust. cowpea aphid-bome mosaic virus, cowpea yellow mosaic virus, south­ern bean mosaic virus, cowpea mottle virus.

Ascochyta, Phytophthora stem rot, cowpea aphid­borne mosaic virus.

Root knot nematodes are a problem in sandy soils. In mixtures with cereals, cowpeas are often planted late and are vulnerable to drought. In the Sahel, heat and dry winds can also cause severe losses.

Research at lIT A

nTA has global responsibility for cowpea research among member institutes of the Consultative Group on Intemational Agricultural Re­search (CGIAR). liT A headquarters lies within the center of origin and genetic diversity of the crop, and within the region which is the world center of production. lIT A has a long-standing cowpea improvement program with strong collaborative links with national programs and with ceriters of advanced research in the developed countries. lIT A also has the responsibility for cowpea gennplasm collection. By 1989, more than 15,000 accessions were being maintained at IITA headquarters. Since 1986, special efforts have been made to collect wild Vigna germplasm which may playa key role in breeding for insect resistance.

lITA's early wort in cowpea improvement was mainly devoted to basic research on crop physiology and to the identification of soun:es of resistance to insects and diseases (tables 1 and 2). Sources of resistance to most of the important diseases were identified and incorpo­rated in breeding lines. Many of the elite lines distributed in international trials since the mid-1970s have high levels of combined resistance to the principal bacterial, fungal and viral diseases.

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Table 1. Sources of resistance to different diseases in cowpea

DlsI!ASI!

Anthracnose, rust, CerCOsfXJra leaf spot

Bacterial pustule

Cowpea yellow mosaic virus, cowpea mottle virus, cowpea aphid. borne mosaic virus, cowpea golden mosaic virus

Fusarilun wilt

Bacterial blight

Scab

Septoria leaf spot

Brown blotch

Root knot nematode

Phytophthora stem rot

RI!SISTANCE SOURCI!S

TVu 310.345,347,410,645

\nrf~·I, \nrf~·3

TVu 393. 410,493,1185,2755, \nrf~·I, V1T~·3

TVu 109·2, 347,984, 1000

TVu 347,410, 483·2, VIT~·3, \nrfA-4

TVu 853, 1404, 1433, VITA-4

TVu456,483·2,486, 1433, VlT~-4

\nrf~·I, \nrfA-4

VIT~-3

Ku235

Table 2. Sources of resistance to different insect pests

Leafhoppers, Empoasca sp. AphidAphis craccivora Thrips, Me galurotJuips sjostedti Legume pod borer, Maruca tutulalls Pod bug, Clavigralla t07Mntosicollis Bruchid, Callosobruchus maculatu.r

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SornlcI!.S OF RESISTA1'CI!

TVu 59,123,662, VIT A-3 TVu 36,62,801,2896.3000 TVu 1509,2870 TVu 1, 946, Kamboinse Local TVu 1, 1890 TVu2027

Late in me 19708. the orientation of the program shifted towan! insect resistance. with the emphasis on insects encountered in Africa. The strategy was to achieve yield stability through resistance to the main pests and diseases.

The cowpea research program focuses on resistance to insect pests and diseases. In addition. from 1988 the main breeding objectives developed new emphases which are reflected in the UTA Medium-Term Plan (1989-1993), as follows: • Morphological and physiological adaptation for inten:ropping with

cereals. • Multiple pest and disease tmstance for incorporation into loca1ly

adapted varieties. • Improve drought tolerance in cowpeas, especially for the millet

cropping systan of tile semi-arid zones. • Resistance to post-flowering pests. • Pest resistance characters from wild Vigna species.

In addition. biotechnology research on wide crosses and contract re­search have been given renewed emphasis.

Research Goals

The aim of cowpea research at lIT A is to reduce the risks in cultivation for the farmer, thereby increasing the farmer's productivity and income.

Short-term goals

Where a high level of resistance to insect pests, diseases, drought, heat and other factors have been identified. the characters are being incorpo­rated in the dite cowpea lines. Shon-term research goals for the different ~logical zones are described here briefly.

Sahel. Emphasis is <Xl the incorporation of resistance to insect pests (aphid, brucbid). diseases (bacterial blight, Macroplwmina ashy stem blight), viruses and Srriga in locally adapted varieties for millet-based cropping systems.

Savanna. Studies include incorporation of resistance to insect pests (aphid, thrips, bruchid). diseases (Septoria leaf spot, scab, web blight.

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bacterial blight, Macrophomina ashy stem blight), viruses, Striga and Alectra in locally adapted varieties, for millet/sorghum and maize-based cropping systems.

Humid Forest and Transition. Studies include incOIporation of resistance to insect pests (aphid, thrips, bruchid), diseases (brown blotch, anthracnose, web blight, Fusarium wilt, Cercospora leaf spot, bacterial pustule, bacterial canker, bacterial blight, brown rust) and viruses, in improved cowpea lines for maize, cassava, yam and rice-based cropping systems and monocrop cultivation. Multiple disease-resistant lines.are being developed for vegetable pods with strong and long peduncles.

Mid-altitudes. Through the Southern African Development Coordina­tion Conference (SADCC) cowpea project, research is being initiated on the identification of major pests. diseases and viruses and other stresses, such as drought and cold tolerance, in the region. Superior local lines are being identified. Insect, disease and virus resistance characters are being incorporated into locally adapted lines.

Long-term goals

Where it bas not been possible to identify high levels of resistance to some of the biological and physical constraints. efforts are being made to identify sources of resistance and incorporation of those resistance sources. Such difficult problems require a long-tenn effort in basic research, and involve new techniques in biotechnology and 'strategic elements in in~grated pest management (rpM). Long-tenn goals for the various agroecological zones are described here briefly.

Sahel. Cowpeas are being developed for millet-based cropping systems, for fodder and grain purposes. with superior morphological and physio­logical characters including drought and heat tolerance. resistance to insect and diseases predominant in Sahel, and Striga resistance. Some effort is also devoted to development of cowpeas for the off-season irrigated crop with cold tolerance.

Savanna. Similarly ,long-term goals consist in development of cowpea with superior morphological and physiological characters suitable for the savanna zones and cropping systems with resistance to the predomi­nant insect pests. diseases, Striga and Alectra. Additional subjects for

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study include inheritance of resistance to some of those important constraints.

Humid Forest and Transition. At UTA headquarters, higher levels and bener sources of resistance to thrips, Maruca pod borer, pod bugs and bruchid are being identified Research continues on the evaluation of wild cowpea and wild Vigna for insect resistance and the development of lines with higher levels of multiple resistance to thrips, Maruca pod borer, pod bugs and bruchid. Other long-term goals in this zone include: biotechnology research in cooperation with advanced laboratories; basic biotechnology research; advancement in methods for screening for resistance and study of the mechanism of resistance to insects. Tactics for IPM systems are being developed. The lIT A Biological Control Pro­gram at Cotonou. People's Republic of Benin. is concentrating on biological control agents for the control of cowpea pests.

Mid-altitudes. Cowpea lines are being developed for cold and drought tolerance, and multiple insect and disease resistance, as in other zones.

Achievements

Several lines with multiple resistance to diseases and resistance to one or more insect pests have been developed. Many of those varieties have been released by national programs.

Sabel. The Semi-Arid Food Grains Research and Development (SAFGRAD) Project team based at Burkina Faso initiated research on drought tolerance and resistance to Slriga in 1980. Through their efforts sources of resistance to those two constraints were identified (tables 3 and 4). Research in this zone was further intensified around 1985. A

Table 3. Cowpea lines less susteptible to drought

VARIETY

VITA-3 TVu662 SUVITA2 TVx 3236

ORIOIN

Kenya Nigeria Burkina Faso IITA

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Table 4. Cowpea lines resistant to Striga gesneribides

VARIETY ORIGIN IOBNTIflED BY

SUVITA-2 Burkina Faso SAFGRAD/IITA Burkina Faso

VITA-3* Kenya Institute of Agricultural Research Samaro, Nigeria

IT82D-849 UTA SAFGRAD/IIT A Burkina Faso

B301*'" Botswana University of Bristol Long Ashton Research Station England

... Also resistant to root knot nematode, Meloidogyne incogrUtQ

...... Also resistant to A ltetra vogelii

cowpea breeder is based at the International Crop Research Institute for the Semi-Arid Tropics (ICRISAT) Sahelian Centre at Niamey. Several lines with resistance to aphid, bruchid, bacterial blight and Macrophom­ina ashy stem blight are being developed. Crosses have also been made for combining Srriga resistance and tolerance to drought. From research conducted through the SAFGRAD project and from lines developed at liT A headquarters, international trials were sent and several lines have been selected in the Sahelian countries by the national programs for further tests or release to farmers for cultivation. VITA-7, SUVITA-2 and TVx 3236 are among the popular lines released in the Sahelian countries.

Savanna. In order to further intensify cowpea research in this zone, a cowpea research station was established in July 1989 in Kano, northern Nigeria. liT A will work closely with the Institute of Agriculturai Research (IAR) at Ahmadu Bello University, Zaria and ICRISAT scientists based at Kano. lIT A scientists at the station include a cowpea breeder, a physiologist and an agronomist.

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Several segregating lines combining aphid. StrigtJ and Alectra resistance appear promising. Several cowpea lines tested through international trials by national programs in the region have been found superior to local improved lines and have been released for cultivation by farmers. TVx 3236 has a moderate level of resistance to thrips with high yield potential. This variety has perfonned well in both the Sahd and savanna ZOfteS. VITA-3, which is resistant to leathoppers, has been released in several Latin American countries where leafhoppers are a major cowpea pest.

Humid Forest and Transition. IITA has succeeded in developing several lines withhigh yield potential (2(XX) kilograms per hectare) with multiple virus resistance (table 5) and with multiple disease and insect resistance (table 6). Cowpea lines have also been developed with medium (7010 75 days) and sbortmaturity (60 to 65 days) with a diversity in seed color and plant type suitable for humid tropics, for cultivation the during short rainy season or during the dry season in paddy rice fallows. These varieties are for grain production as sole crops using insecticides to control pests. Their yield, with improved management but no fertilizer, is more than 100% greater than traditional varieties. The improved varieties require less spraying with insecticides because of their short duration and partial resistance. Cowpea lines 11'81D-994, ITSID-1137 and IT84S-2246-4 appear to be most promising. The cash cost of spraying is only a small fraction of the value of the increased output in many countries. Insecticides which are effective against cowpea pests include cypermethrin mixed with dimethoate (Sherpa Plus·,Cymbush Super ~; lambda-cyhalOOuin mixed with dirnethoate (Karate Super ED-); alphamethrin (Fastac-) and biphenthrin (Talsta"').

WUd Vigna species were screened for resistmce to major pests of cowpeas. Several species appear to have high level of resistance to some of the major pests (table 7).

Mid-altitudes. An IITA cowpea breeder was based in Kenya with the International Centre for Insect Physiology (ICIPE) from 1985 to1987. During this two-year period, several local cowpea varieties and IITA lines were identified with superior agronomic character. Among the nTA lines tested in the region, IT82D-889, IT82D-885, IT82D-789 appear to perform Qetter than others. A SADCC cowpea project was

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approved during 1989, with funding from the European Economic Community. Through this project, the needs of southern African countries are being served and varieties suitable for eastern Mrica are expected to be developed.

Table 5. High.yieldiol multiple \'irus resistant cowpea lines ,

VARIETY CYMV CAbMV CMeV CuMV SBMV MAnnuTY (DAYS)

mID-Il37 R R MR MR MR 73-80 IT82E-I6 R R MR R R 63-70 IT82D-889 R R MR S R 55-60 lT83S-8I8 R R MR R R 60-56 IT83D-442 R R R R R 5>60 IT84D-449 R R S R R 75-80 IT85F-867-5 R R R R R 60-65 IT85F-2687 R R R R R 65-70

Notes: CYMV ;;;; cowpea yellow mosaic virus R ;;;; resistant CAbMV ;;;; cowpea aphid-borne mosaic virus MR ;;;; modecately resistant CMeV ;;;; cowpea mottle virus S ;;;; susceptible CuMV ;;;; cucwnber mosaic virus SBMV ;;;; southern bean mosaic virus

Table 6. High-yielding advanced breeding lines with insect resistance

PEST

Leafhoppers. Empoasca sp.

Aphids, Aphis crlJCcivora

Thrips. Megalwothrips sjostedti

Bruchid. CallosobrllChus maculalus

Thrips. M egllUuolitrips sjostedti bruchid, CallosobrllChus macwatus

Aphids ,Aphis crlJCcivora. thrips. Megalurothrips sjostedti bruchid. Cal/osobrllChus macwatus

RESISTANCE ~ES

VITA-3

11'810-1007, ]1'81D-1020, IT82D-806, 11'82o.807.11'82D-717

TVx3236

I1'8lO-994.I1'81D-1137. IT81D-1157

I1'82D-716.11'84S-2231-15

11'83S-728-5, ITS3S-742-11. I1'83S-742-13,IT84S-2246-4

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Table 7. Evaluation of resistance to cowpea pests in wild Vig,",

SP!CJI!S APHIDS THRIPS BaucHlDs MARUCA PoD BUGS

POD BOREa

V. IUIguicJdata ssp. dekiruJliaM

var. dekindtiana R,S S R R var. pubescens R,S S R R var. protracta R,S S R R

V.IUleola R R R V. "txi/lata R R R R V. oblongifoUa S R,S R R V. recriculata R R,S R S

Source: llTA.1989 Notes: R = Resistant S = Susceptible

Impact

Fifty-one countries world-wide in different agroecological zones have benefited from the numerous cowpea lines developed through lIT A (table 8). 1bese cowpea varieties have been released to fanners for cultivation by the national programs. Several lines are also utilized by national programs for incorporation of useful traits into the local varie­ties.

The thrip-resistant cowpea variety TVx 3236 is popular with fanners in the nonhem parts of Nigeria, Cameroon (savanna), Senegal (Sahel) and Botswana. Along with TVx 3236. the variety ER-7 is popularly cultivated by fanners in southern Africa, particularly in Botswana.

Several lines with multiple resistance to diseases have been developed. including Vita-l and Vita-3 which have already been re­leased. Vita-3. with tolerance to drought and resistance to leafhoppers, is popular in Latin America where leafuoppers are a major pest of cowpea. It is extensively cultivated by fanners in Brazil, Jamaica and Guatemala.

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The recently developed line IT84S-22464 has multiple resis­tance to aphid, thrips and bruchid. Other recently developed varieties IT81 D-994 and IT81 D-1137 are resistant to bruchid and have performed consistently better than most varieties in international trials in several countries in West Africa.

Table 8. Improved cowpea varieties from lIT A selected by national programs

COUNTRY

Angola Argentina Belize Benin. People' s

V ARlETY RELEASED

TVx3236

VITA-3

V ARlI!TIJ!S UNDER LAIlOI!-SCAl£

ON-FARM TEST AND SEED

MULTIPUCATION FOR RELI!.ASB

IT82D-716 IT82E-18.IT82D-889. IT82D-789

Republic BurkinaFaso Bolivia Botswana Brazil

VITA-4. VITA-5 IT82E-32.IT8ID-1137 TV)!: 3236. KN-l (VITA-7) IT82D-442.11'82D-889 ER-7. TVlt 3236 VITA-7. TVx 1836-013J VITA-6. VITA-3. 4R-0267-0IF

Bunna VITA-4 Cameroon TV)!: 3236 Equatorial Guinea

Central African Republic

Colombia Costa Rica Ethiopia EI Salvador Equador Fiji Ghana

Guatemala Guyana

Haiti India

VITA-I. VITA-4. VITA-5

VITA-3

VITA-3. VITA-5 VITA-3 VITA-I. VITA-3 TV)!. 2724-0IF. IT82E·16. IT82E-32. TVx 1843-1C VITA-3 ER-7. TVx 2907 -02D. TVx66-2H. VITA-3 VITA-5 VITA-4, TV)!: 1502

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ITBID-985. TVx 1850-01E IT82E-18. IT82D-812. IT8ID-1137. IT82D-885.

TVu 352. TVu 256-1. TVu 335-1 VlTA-l, VITA-6 VlTA-4. IT82E-16. IT82E-32 TVx 1836-013J TVx 1836-011. TV)!: 3380

IT82E-18. IT8ID-1137, IT83S-S1B

TVx 1843-01C

COUNTRY VARIETY RELEASED VARIETIES UNDeR LARGE-SCAU;

ON-fARM 11!ST AND SEI!D

MULTlPUCATION FOR RELEASE

Jamaica VJTA-3.ER-7 TVx 2124-01F. TVx 1850-01E Liberia VITA-4. VITA-?

TVx 3236. VITA-5. IT82D-889

Malawi 11'82E-25. IT82D-88 9 Mauritius TVx3236 TVx 1836-0131,

TVx4654-44E Mozambique IT82E·18 Nicararua VITA-3 Nigeria TVx 3236, 11'82E-60 11'84E-124.IT84E-I08.IT82D-716

11'81 D·994. 11'82D-951 Pakistm VITA-4 Panama VITA-3 Peru VITA-7 Philippines IT82D-889 Republic of Korea VITA·5 Senegal TVx3236 Sierra Leone TVx 1999-0IE Somalia TVx 1502 IT82D·889.IT82E·32. IT82D-113? South Yemen VITA·5. VITA-7 Sri Lanka TVx 930-01B. lT82D-789

TVx 309-010, VITA-4. IT82D-889

Surinam 11'82D·889,11'82D-789 Swaziland 1182E-18. IT82E· 32 IT82E-18, IT82E· 27

ITB2E-71 Tanzania lX-I. TK-5 IT82D-889.IT82D·890 Thailand VITA-3,1T82D-889 Togo VITA-5, TVx 3236 Uganda lVll 3236. 11'82E·60 Venezuela VITA-3 Yemen TVx 3236, IT82D-789

V1TA-5 Zaire lT82E-18 VITA-5. VITA·7, TVx 3236.

IT82E-32 Zambia TVx 456-01F.1Vx 30-lG TVx 3236, TVx 309-OlG,

11'820-889 Zimbabwe ER-7, VITA-4.1Vx 3236.

11'810-985.11'820-952, I18ID·llS7

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Earlier, cowpea was not a popular crop in the high-rainfall areas of West and Central Africa. With the advent of improved, more versa­tile varieties, it is now possible to grow the crop successfully in these zones as well. Short-duration cowpeas which are suitable for cultivation in the humid zone during short rainy season or during dry season in paddy rice fallow have been developed; ITS} D-I137, IT82D-889, 1T83S-818 and lT84E-I 08 are being released in few countries in Africa antl Asia. However, all these varieties need insecticide protection in ordertO obtain higher yield.

Collaborative and contract research

lIT A works closely with many national agricultural research systems in sub-Saharan Africa and other tropical regions of the world. in the development and adaptation of new technology for cowpea production. liT A collaborates with advanced laboratories in specific problem areas for basic research and has initiated con~ct research for solving some of the difficult crop protection problems. These include resistance to post­flowering pests of cowpeas through interspecific hybridization; resis­tance toStriga andAleetra; resistance to root knot nematode and cowpea aphid biotypes in the tropics.

In Nigeria, liT A has arranged contract research on (a) resistance to Striga gesnerioides and Aleetra vogel/i with the Institute of Agricul­tural Research at Ahmadu Bello University, Zaria and (b) resistance to root knot nematodes at the University of Ibadan. UTA collaborates on resistance to bruchids, Callosobruchus maeulatus and Bruchidius atroIineatus al the Federal University of Technology. Akure and School of Biological Sciences, Imo State University, respectively. In Niger. lIT A works closel y with Institut National de Recherches Agronomiques du Niger on Macrophdmina ashy stem blight resistance; and in Zambia. with Msekera Regional Research Station, Chipata, on cowpea aphid­borne mosaic virus, among others.

Work with advanced laboratories at Italian institutions (Univer­sitAdegliStudidiNapoli and Istituto del Germoplasma. Bari) and a U.S. institution (Purdue University) has recently focused on biotechnology research for resistance to post -flowering insect pests and cowpea bruchid resistance. The Government of Italy has supported this basic research.

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liT A has contract research arrangements for the biotechnology research with Purdue University. UTA also collaborates with the University of Durham. where the mechanism of bruchid resistance in TVu W27 and cowpea trypsin inhibitor gene (CpTI) were originally identified. TVu 'lOTI was identified as resistant to bruchid by lIT A in 1974.

ICIPE in Kenyahas worlc.ed with lIT A in the development of diet for Maruca pod borer under a research contract for a period of three years, funded by the Gennan Technical Cooperation (GTZ). UTA has also collaborated with lOPE in the identification of mechanism of resistance to Maruca pod borer in TVu 946, and research on IPM in cowpea mixed cropping with other cereals. In the U.K., UTA has contract research arrangements with Wye College for cowpea aphid biotype resistance research and identification of geographical races of this pest in the tropics. With the University of Bristol, Long Ashton Research Station, UTA collaborates for Striga research which has resultedintheidentificationofB301Striga and Alectra resistant cowpea by the Long Ashoon group. B301 is the only line which appears to be resistant to virtually all the strains of Striga and Alectra in West Africa. liT A has collaborated in the past with the Plant Environment Laboratory. Department of Agriculture, University of Reading. in cowpea physiol­ogy research. This collaborative arrangement is again being initiated with the recent addition of a cowpea physiologist.

UTA has submitted a proposal to the Directorate General for International Cooperation of the Netherlands Government for funds for contract research with several institutes in the Netherlands: the Depan­ment of Molecular Biology. Agricultural University; Research Institute for Plant Protection (IPO); Depanment of Tropical Agriculture, Wagen­ingen. Collaborative attempts are being made to transfer the coat protein gene of cowpea aphid bome-mosaic virus (CAbMV) to cowpeas, by innovative biotechnology techniques. giving a novel approach for the control of several strains of CAbMV. This work could possibly provide for control of otherpotyviruses affecting cowpea (a total of 8 potyviruses are reported from cowpea from all over the wOrld).

Itis envisaged thatcoll~.borative studies will be initiated with the Bean/Cowpea Collaborative Research Support Project, Michigan State University and with the Boyce Thompson Institute, U.S.A., to identify fungal, bacterial and viral pathogens involved in control of cowpea pests.

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The results of these cumulative efforts should ultimately help in solving some of the more difficult cowpea production problems and make the crop less risky and more profitable to farmers in the tropics.

References

8ressani. R. 1985. Nutritive value of cowpea. In Singh, S.R. and Rachie, K.O. (eds). Cowpea Research,Production and Utiliza­tion. 10hn Wiley & Sons. Chichester, UK. p.353-359.

Rachie, K. o. 1985. Introduction. In Singh, S.R. andRachie, K. O. (eds). Cuwpea Research, rroduction and Utilization. John Wiley & Sons. Chichester, UK. p. xxi-xxviii.

Singh. S. R. and Rachie. K. O. 1985. Cowpea Research. Production. and Utilization. John Wiley & Sons. Chichester, U.K.

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