Root and Leaf Traits for Dehydration Avoidance and Enhanced Grain Yield in Cowpea ( Vigna unguiculata L., Fabaceae) Under Drought

Drought stress, which is exacerbated by climate change, is a major contributor to crop production losses in rainfed agriculture. Two genotypes of cowpea ( Vigna unguiculata , (L.) Walp.) with determinate (IT‐16) and indeterminate (IT‐96D‐610) growth patterns were grown either well‐watered or subjected to drought stress at vegetative and flowering stages in a pot experiment in a glasshouse. Stomatal conductance (g s ) and soil moisture were measured daily during the drought stress periods, while chlorophyll fluorescence data were collected every third day. Both genotypes maintained relatively high‐water content (RWC > 80%), indicating dehydration avoidance; however, IT‐96D‐610 consistently maintained a higher RWC than IT‐16. Under drought stress, IT‐96D‐610 exhibited lower g s and less sensitive stomata, greater total root length, root surface area and a higher root‐to‐shoot ratio compared to IT‐16. These traits were associated with higher seed yield and water productivity in IT‐96D‐610 than in IT‐16. In contrast to IT‐96D‐610, genotype IT‐16 showed higher photosynthetic efficiency, indicated by higher F q′ /F m′ and qP, and produced more biomass, but with reduced grain yield. This study underscores the importance of selecting traits for dehydration avoidance, such as RWC, deep‐fine roots and moderated stomatal conductance, in cowpea breeding programs aimed at improving productivity under drought conditions.