Evaluation of cowpea genotypes for soil moisture stress tolerance under screen house conditions.

Abstract

A potted experiment was conducted in a screen house at the University of Ilorin, Nigeria to evaluate the growth and grain yield responses of 10 genotypes of cowpea to soil moisture stresses. The experiment was designed as a 4 x 10 factorial and laid out in split-plots arrangement, evaluated ten genotypes of cowpea at four soil moisture stress levels with all factorial combinations replicated four times. Growth and flowering parameters were measured at full flowering, while yield components as well as grain yield per plant were determined at plant maturity. All data collected were analysed using analysis of variance and moisture stress tolerance was evaluated by the rank summation index (RSI). Plant height, numbers of leaves and flowers per plant increased significantly with decreasing soil moisture stress. However, higher soil moisture stress levels have no appreciable effects on branching, but delayed onset of and time to full flowering. Numbers of pods and seeds, HI and shelling percentage as well as grain yield decreased with increasing soil moisture stress, while biomass yield was not significantly influenced by the stress. The overall rankings of the evaluated genotypes in terms of growth and grain yield responses to soil moisture stress tolerance from the best to the worst are IT97K-499-38 > IT99K-1060 > ITA 271 > IT99K-1245 > ITA 352 > IT97K-598-18 > IT98K-131-2 > IT97K-356-1 > IT98K-491-4 > IT00K-901-5. Not withstanding these ranks, ITA 271 and ITA 352 had the best yield stability, while IT99K-1060 was drought tolerant but has low yield potential. Key words: Cowpea (Vigna unguiculata), genotypes, soil moisture stress, growth and grain yield responses, yield potential, stability.