Screening Lablab (Lablab purpureus L. Sweet) accessions for drought tolerance at the seedling stage based on their physiological responses to drought stress

Lablab serves a multifunctional role, contributing to both human food and livestock feed. It contributes significantly to the conservation agriculture practices, food security sustainability, and livelihood enhancement, especially under persistent drought conditions. Although it has many advantages, Lablab remains an underutilized crop in many countries. These countries continue to lack access to improved varieties that possess both high yield potential and drought tolerance. This study aimed to screen different Lablab accessions for drought tolerance at the seedling stage, based on their physiological responses to drought stress. The study was carried out in the screen house at Tanzania Agricultural Research Institute (TARI) - Selian in Arusha, Tanzania through two repeated experiments. The experiments involved 302 test accessions and 3 checks, each assigned Dolichos (D) accession number, and arranged in the Augmented Complete Block Design (ACBD). Thirty-two blocks were established through repeated randomization of the accessions at each experiment. Ten seeds per accession were sown in each block and different watering regimes were applied in phases during each experiment to manage the screening process. Data collection involved different seedling traits at each phase. These traits were then subjected to various statistical analyses. Descriptive statistics were created from the qualitative responses to explain the accessions' performance, while the Analysis of Variance (ANOVA) and a range of means for the quantitative responses were performed to determine variations among the accessions. The drought-tolerant (DT) and drought-susceptible (DS) accessions were selected based on their performance in qualitative traits and a range of means for each quantitative trait across the experimental phases. The findings revealed a great variation among the accessions for their qualitative and quantitative ( p < 0.05∗, 0.001∗∗, and 0.0001∗∗∗) responses to drought stress across the experimental phases. Based on the qualitative and quantitative responses of the accessions to drought stress, D349, D147, HA4, D363, D352, D359, D348, D311, D55, and D250 were selected as the DT accessions while D271, D66, D106, D6, D26, D255, D28, D186, D95, and D258 were identified as the DS accessions. These accessions were recommended for the biochemical and molecular analysis to determine the basis of their drought tolerance under stressed and non-stressed conditions. Finally, they were recommended for seedling-stage and yield-performance evaluation in arid and semi-arid environments to contribute to the development of high-yield, and drought-tolerant varieties prior to their commercialization.