Cowpea (Vigna unguiculata L Walp)

Cowpea (Vigna unguiculata L. Walp.) is a widely adapted, stress tolerant grain legume, vegetable, and fodder crop grown on about 7 million ha in warm to hot regions of Africa, Asia, and the Americas. This review focuses on major breeding achievements, current objectives, and future opportunities for cowpea improvement. Early maturing cultivars have been developed with regionally acceptable grain quality and resistance to some important diseases and pests including bacterial blight (Xanthomonas campestris), cowpea aphid-borne mosaic virus (CABMV), cowpea aphid (Aphis craccivora), cowpea curculio (Chalcodermus aeneus), root-knot nematodes (Meloidogyne incognita and M. javanica), cowpea weevil (Callosobruchus maculatus) and the parasitic weeds Striga gesnerioides and Alectra vogelii. Earliness is important in Africa and other regions because early cultivars can escape drought and some insect infestations, can provide the first food and marketable product available from the current growing season, and can be grown in a diverse array of cropping systems. New early maturing cultivars with indeterminate growth habits have been very effective in the extremely dry and hot environment of the Sahel. Heat tolerant breeding lines have been developed which have markedly higher pod set than most cultivars under high night temperature conditions. Development of cultivars with multiple resistances to biotic and abiotic stresses is an important current breeding objective. Earliness, delayed leaf senescence, and indeterminate growth habit are characteristics which are being combined to improve drought adaptation. In the future, high levels of resistance to very important insect pests such as flower thrips (Megalurothrips sjostedti), maruca pod borer (Maruca testulalis), lygus (Lygus hesperus), and pod bugs (Clavigralla tomentosicollis and others) need to be identified. Genes from wild cowpeas or related Vigna species or genetic engineering may be necessary to develop cultivars with high levels of resistance to several of the major insect pests. (C) 1997 Elsevier Science B.V.