Selection for Postflowering Drought Resistance in Short‐ and Medium‐ duration Cowpeas Using Stress Tolerance Indices

Abstract

ABSTRACTAvailable drought‐tolerant cowpeas [Vigna unguiculata (L.) Walp.] are few, and identification of additional genotypes with even greater tolerance to drought would enable breeders to develop cultivars with higher and more stable yields across the semiarid ecologies where this crop is grown. The objectives of this work were to evaluate the effects of drought on the growth and reproduction of a diverse set of cowpea germplasm and select drought‐tolerant and high‐yielding genotypes using stress tolerance indices. Thirty short‐ and 30 medium‐duration genotypes were separately assessed in adjacent drought‐stressed (DS) and nonstressed (NS) environments in a randomized complete block design with three replications. Selection indices, including stress tolerance index (STI) and geometric mean productivity (GMP), were estimated considering grain yield under NS and DS environments and the stress intensity. Overall, the medium‐duration genotypes had higher yields than the short‐duration ones under both DS and NS conditions. On average, fodder and grain yields were 40 and 65% less under DS conditions and maturity occurred 4 d earlier. IT85F‐3139, IT93K‐693‐2, IT97K‐499‐39, IT93K‐503‐1, IT96D‐610, IT97K‐207‐15, KVx‐61‐1, KVx‐403, KVx‐421‐25, and Mouride had the highest grain yields under both DS and NS environments and were identified as the most drought‐tolerant and high‐yielding genotypes based on their rank in terms of STI and GMP values. Therefore, these cultivars may be valuable parents for breeding programs whose objectives include developing drought‐tolerant cowpea cultivars.