2019 ASHS Annual Conference

Cowpea [Vigna unguiculata (L.) Walp] is a diploid legume species (2n=2x=22) widely cultivated in Africa, Asia, southern Europe, southern and western U.S., Central and South America, the Middle East, and Oceania. The estimate of cowpea seed production is about 5.4 million tons globally. Drought stress has been one of the most important abiotic stresses affecting crop production worldwide. Water deficit conditions can lead to a significant yield decrease in cowpea. Breeding for more drought-tolerant cowpea cultivars would be vital to limit the impact of drought stress on cowpea production. This can be done by exploring different loci that potentially contribute to drought tolerance. Reduction in plant height, stem diameter, and chlorophyll content could be used as parameters to evaluate tolerance to drought conditions in cowpea and can lead to the discovery of new drought-tolerant loci. Therefore, the objective of this study was to evaluate the variation in decrease in plant height, stem diameter, and chlorophyll content in cowpea under drought stress. A total of 331 cowpea genotypes were evaluated for drought tolerance under greenhouse conditions and organized in a Randomized Complete Block Design (RCBD) with 3 blocks. Plant height, stem diameter, and chlorophyll were evaluated prior to applying drought stress, when 50% of the susceptible control (PI25574) showed chlorotic leaves, and when the susceptible control was completely dead. Drought tolerance index ((Non-stress – Stress)/ (Non-stress) x 100), stress indicator 1 ((Final/Before stress) x 100), and stress indicator 2 ((Data when 50% of susceptible control showed chlorotic leaves) /(Before stress)) x 100) were calculated for each trait The preliminary results showed a large variation in those traits among the 331 cowpea accessions. These results will be useful in breeding programs developing drought-tolerant cowpea cultivars.