Deciphering the morpho-physiological and biochemical responses in Lablab purpureus (L.), Sweet, seedlings to water stress

Abstract

Drought is a major crop productivity-limiting factor, which adversely affects growth and yield worldwide. Lablab (Lablab pupureus [L.] Sweet), is better adapted to withstand drought stress, however, characterization of lablab in Kenya has not been undertaken and there is limited knowledge on plant response to drought stress. Ten lablab genotypes were evaluated under greenhouse to determine the morpho-physiological and biochemical response at the seedling stage. The study revealed significant differential responses among lablab genotypes to water stress. The interaction between the water stress and the genotypes significantly affected the evaluated traits. Genotypes D1 and D6 showed significantly increased and superior morphological adaptation, respectively, indicating enhanced adaptation for tolerance to water stress. Significant variations of ascorbate peroxidase, guaiacol peroxidase and catalase activities were detected during the experimental period. The plants exhibited varying non-enzymatic antioxidants and osmolytes with an increase in proline, total phenol and water-soluble carbohydrates and a decline in free amino acids and water-soluble proteins under severe water stress. Genotype D10 recorded high antioxidant enzymatic activity and water-soluble carbohydrates, whereas D1 accumulated more proline and proteins, indicating better adaptation in scavenging reactive oxygen species to prevent membrane damage. The higher photosynthetic efficiency of seedlings of genotype D1 and superior morphological adaptation of D6 indicated better agronomic adaptation to severe water stress and could be utilized in plant breeding programmes for tolerance to drought.