Improving the efficiency in breeding cowpea for adaptation in semi-arid tropics

African Crop Science Journal,Vol. 5. No. 4, pp. 325-340, 1997 Improving the efficiency in breeding cowpea for adaptation in semi-arid tropics N. MULEBA, J.T. OUEDRAOGO, I. DRABO and C. DABIRE Code Number:CS97039 Sizes of Files: Text: 42.6K Graphics: Line drawings and tables (gif) - 101.4K ABSTRACT Crops in semi-arid tropics (SAT) are subject to yield losses due to drought and heat stress as well as excess moisture. Cultivars in these ecologies should be genetically buffered against environmental variations to ensure food security. A strategy for combining, in a cross, genes for high yield, tolerance to drought, heat and excess moisture, and resistance to associated diseases is presented. The research objective was to improve, over currently used breeding approaches, the efficiency in developing high yielding and highly adapted cowpea (Vigna unguiculata L. Walp.) cultivars. To this end, crosses were made involving parents of various characteristics and origins. Offsprings from the crosses were first screened for disease resistance. They were then subjected to a successional sowing cultivar evaluation (SSCE) for the identification of productive and adapted genotypes and were further evaluated for adaptation in various SAT in Burkina Faso. Selected recombinant genotypes were further evaluated for adaptation in various SAT ecologies in West and Central Africa. New, higher yielding and better adapted genotypes were identified only from crosses that involved high yielding parents adapted to extreme conditions in the different ecologies in the sub region. Some of the recovered genotypes showed stable, high yields and good adaptation in specific and also across different ecologies in semi-arid West and Central Africa. This indicated that the breeding strategy used was effective for the development of cultivars highly adapted to semi-arid tropical conditions. Key Words: Adaptation, breeding, drought, excess moisture, resistance, semi-arid tropics, stability, tolerance, Vigna unguiculata, yield RESUME La culture du niebe (Vigna unguiculata L. Walp) en zones semi-arids tropicales subit d'importantes chutes de rendements subsequantes a la secheresse et/ou au stress thermique ainsi qu'a l'exces d'humidite. Les cultivars diffuses dans ces zones ecologiques doivent etre genetiquement tamponnes contre les aleas climatiques afin d'y securiser la production alimentaire. Une strategie: d'apport, par croisements, d'un ensemble des genes fonctionnels pour la haute productivite et la resistance/tolerance a la secheresse, au stress thermique et a l'exces d'humidite y compris les maladies qui y sont associees en vue de favoriser, par brassage, la formation des genotypes de recombinaison tres productive et a adaptation tres large est ici presentee. L'enjeu de cette recherche etait d'ameliorer l'efficacite du developpement de nouveaux cultivars de niebe hautement productifs et bien adaptes. A cet egard, des croisements impliquant des parents des caracteristiques et d'origines diverses ont ete effectues. Les descendants issus de ces croisements ont d'abord ete cribles pour la resistance aux maladies. Ensuite, ils ont ete evalues au Burkina Faso en utilisant differentes dates de semis. Ceci afin de les exposer aux conditions variables de l'environment et de selectionner ceux ayant un bon comportement tout en etant hautement productifs. Les genotypes ainsi selectionnes ont en-outre fait l'objet d'evaluation dans diverses ecologies de la zone semi-aride de l'Afrique du Centre et de l'Ouest. Quelques genotypes de recombinaison, hautement productifs et bien adaptes, ont ete recouvres seulement dans les populations issues des croisements dont les parents etaient tres productifs et adaptes aux conditions extremes dans les differentes ecologies de la zone semi-aride. Certains de ces genotypes ont exhibe non seulement un haut rendement stable, mais aussi une bonne adaptation tant aux conditions specifiques qu'a travers les differentes ecologies semi-arides en Afrique du Centre et der L'Ouest. II apparait donc que la strategie utilisee a ete tres efficace pour le developpement de nouveaux cultivars de niebe a haute productivite et bien adpates aux conditions semi-arides tropicales. Mots Cles: Adaptation, amelioration, exces d'humidite, rendement, resistance, secheresse, stabilite, tolerance, Vigna unguiculata, zones semi-arides tropicales Copyright 1997 The African Crop Science Societ