Screening for drought tolerance in cowpea at the flowering stage

Drought is one of the major threats to cowpea productivity in tropical countries, and understanding its impacts is germane in ensuring food security in a global context. The present study was established to screen some accessions of cowpea for drought tolerance at the flowering stage in pots under the controlled conditions of a screen house. High significant differences were observed among accessions for wilting and recovery traits, stomatal conductance, relative water content (RWC), terminal leaflet length (TLL) and width (TLW), stem girth, and yield parameters under drought stress. In addition, drought stress caused a significant reduction in morphological traits and RWC between the initial and the final values. Based on cluster and Principal Component Analysis (PCA), accessions were separated into different classes of tolerance. Direct selection for wilting traits, stomatal conductance, morphological traits, and recovery parameters showing high heritability (≥ 60%), GAM (≥ 20%), and PCA (≥ 0.4) will be effective. Hence, four major classes of tolerance were determined: AC03, AC08, and AC10 were highly susceptible. AC01 and AC04 were moderately susceptible. AC06, AC07, and AC09 were moderately tolerant, while AC02 and AC05 were the highly tolerant accessions. The moderately tolerant and the highly tolerant accessions showed a combination of superior resistance to wilting, superior recovery rates, and superior yield attributes. They also showed lower stomatal conductance, higher RWC, and low reduction of RWC, TLW, and stem girth under drought stress compared to the susceptible ones.