Physiological and Biochemical Aspects Involved in Tolerance to Water Deficit in Traditional Cowpea

Purpose Cowpea ( Vigna unguiculata ) is a significant protein source in tropical and subtropical regions worldwide. However, its cultivation in the Brazilian semi-arid region is primarily associated with irregular rainwater. Thus, the objective of this study was to carry out a physiological and biochemical characterization of traditional genotypes of cowpea under drought. Methods The analyse encompassed physiological and biochemical variables that affect the growth and development of cowpea under water restriction conditions. Three genotypes of cowpea, Pingo de Ouro 1–2, Sempre Verde, and Feijão de Moita, were evaluated. The experiment was conducted in a greenhouse using a completely randomized design, with a 3 × 3 factorial scheme (3 genotypes and 3 soil water conditions) and 5 replications. Results Morphological analysis revealed that shoot height, number of leaves, and leaf area were particularly sensitive indicators. Organic solute accumulation, particularly in the Pingo de Ouro 1–2 and Feijão de Moita genotypes, emerged as a distinct trait in response to severe water stress. Additionally, enzymatic activity associated with redox metabolism highlighted variations in the Feijão de Moita and Pingo de Ouro 1–2 genotypes, indicating their adaptive responses to oxidative stress induced by drought conditions. Conclusions The genotypes Pingo de Ouro 1–2 and Feijão de Moita showed high water use efficiency, accumulation of organic solutes, and antioxidant enzymatic responses under water stress, indicating the potential for breeding toward drought tolerance in arid regions.