Impact of Mild Water Stress During the Flowering Stage on Leaf Functional Traits and Yield of Selected Cowpea Varieties Grown in The Low Country Dry Zone of Sri Lanka

Cowpea [Vigna unguiculata (L.) Walp.] is an important legume growing in tropical regions. Cowpea is grown in the Dry Zone of Sri Lanka as an inter-season crop. Rising temperatures and unpredictable precipitation patterns are major factors contributing to soil moisture stress in tropical agriculture. Despite the short life cycle, it is highly likely that cowpea experiences mild soil moisture stress (around 70% of field capacity) conditions at flowering stage due to enhanced evapotranspiration in response to increasing air temperature. In this study, five cowpea varieties were subjected to two soil moisture conditions; field capacity and mild water stress, at the onset of flowering under a split-plot design for two consecutive inter-seasons with the objectives to determine the leaf gas exchange and hydraulic traits of cowpea exposed to soil moisture stress and the underlying relationships between yield reduction and leaf gas exchange, hydraulic, and agronomic traits. The yield reduction (p