Biochemical responses of lablab <i>(</i> <i>Lablab purpureus</i> L. sweet <i>)</i> accessions to the water stress in leaves at seedling stage

Abstract

A few crop species, such as lablab, pigeon peas, cowpeas, and Bambara nuts, possess some abilities to tolerate drought conditions. Despite its multipurpose and promising drought resilience, lablab has been the subject of few studies examining its initial biochemical responses to drought stress in dry regions. This study aimed to assess the biochemical responses of lablab accessions to water stress in leaves at the seedling stage to determine potential drought-resilient accessions. Lablab was selected because of its multiple benefits, such as drought resilience, rich sources of different nutrients, especially protein, and its role in conservation agriculture compared to other legumes. In this study, water stress was selected as the parameter of interest because drought is among the major abiotic challenges that contribute significantly to the decline of food productivity worldwide. Fifteen lablab accessions were subjected to both water-stressed (ST) and non-stressed (NS) environments in three replicates in a screenhouse after emergence. The experiments included two checks. Data collection was conducted on the ST and NS experiments involving four biochemical responses, i.e. total chlorophyll content, phenolic content, flavonoid content, and hydrogen peroxide (H₂O₂) content, which were measured every two days. ANOVA and post hoc Tukey tests (p ≤ 0.05) were conducted using GenStat and R software to assess differences among the accessions across seedling traits, days, and water regimes (WRs). The results showed a significant difference (p < 0.05) in the biochemical responses based on accessions, WRs, and their interactions. While the total chlorophyll content was significantly suppressed by ST conditions, the levels of total phenolic content and flavonoid content increased in response to the elevated H₂O₂ content. These findings highlight the important role of biochemical traits in drought adaptation. The accessions HA4, D352, D349, D250, D311, D359, D147, and D55 emerged as the best drought-tolerant (DT) candidates. The recognition of these accessions as the DT accessions necessitates further validation through molecular trait correlation and field evaluation under arid or semiarid conditions.