Breeding for Abiotic Stress Tolerance Cowpea in West Africa

The cowpea breeding program at SARI is collaborating with UCR and other institutions in West Africa. Among the major cowpea breeding activities at SARI is breeding for abiotic stress tolerance cowpea. SARI has assembled large cowpea genetic resources which are being rigorously screened for sources of resistance/tolerance. Drought and heat have been our focus in developing abiotic tolerance cowpea for West Africa. The search for sources of drought tolerance uses seedling stage and terminal drought screening. The heat screening involves field evaluation when both day and night temperature are high which affects flowering, podding and predispose the cowpea plants to heat and drought-related diseases such as Macrophomina. The results so far showed that for seedling stage drought tolerance, low leaf wilting index, high survival rate and higher number of leaves per plant were useful criteria for identifying drought tolerant genotypes. Yield under drought stress was correlated with number of pods per plant and pod length. A principal component biplot display of yield and quantitative indices of drought tolerance identified genotypes that combined high yield and high drought tolerance. The heat screening also Identified one of SARI’s most important varieties (Songotra) as very susceptible to Macrophomina disease under heat. Sources of heat tolerant genotypes are being used to improve the tolerance of Songotra to heat-related diseases. Similarly, crosses are being carried out to improve the drought tolerance of farmer preferred varieties. A search among advanced populations for lines that combines drought and/or heat tolerance with other farmer preferred traits is ongoing.