Drought tolerance assessment of Bambara groundnut (Vigna subterranea L. Verdc) accessions based on morphological and physiological traits

Abstract

Understanding the adaptive responses of Bambara groundnut (Vigna subterranea L. Verdc) under water-limited conditions is vital for improving resilience of this crop in semi-arid agriculture. This study evaluated the growth, yield, physiological, and photochemical responses of 24 Bambara groundnut accessions under drought stress and non-stress conditions. Significant variation (p < 0.05) was observed among accessions for key morphological traits such as leaf length, plant height, and petiole number. Drought stress markedly reduced biomass and seed yield, with Acc 97 and Acc 100 demonstrating superior yield under stress. Physiological responses showed significant declines in photosynthetic rate, stomatal conductance, and chlorophyll fluorescence parameters under drought. However, accessions such as Acc 25, Acc 61, and Acc 87 maintained relatively higher water-use efficiency and photochemical stability, indicating better drought adaptation. Drought indices highlighted Acc 200, Acc 190, and Acc 175 as promising genotypes, combining high yield potential and stress tolerance. Principal component analysis revealed that photosynthetic efficiency and biomass traits predominantly contributed to phenotypic variation under stress. Overall, this study identified genetically diverse and drought-resilient Bambara groundnut accessions with potential for targeted breeding programs aimed at enhancing drought tolerance and securing food production in marginal environments.