Phenotypic Characteristics of Lablab (Lablab purpureus L. Sweet) Accessions Compared Between Water Stressed and Non-Stressed Seedling Phases to Determine Stress Tolerant Accessions in Semi-arid Conditions

Abstract

Drought poses a severe threat to agriculture, particularly in sub-Saharan Africa (SSA) where the effects of climate change are most noticeable. There are few crop’ species that are able to resist drought stress. Despite the fact that Lablab is a multipurpose crop with high potential on drought tolerance, little research has been conducted to evaluate the crop's early responses to the drought stress in arid and semi-arid conditions. This study therefore aimed to identify stress-tolerant Lablab accessions by analyzing their phenotypic seedling traits under different moisture regimes (MR) in semi-arid conditions. In the study, seventeen potential accessions were subjected to the water stressed (S/ST) and non-stressed (NS) experiments in screen-house after germination. Two checks were considered in the experiments. Throughout the three repeated experiments, data collection involved several morpho-physiological traits including plant height, root length, shoot and root biomass, and relative water content (RWC), monitored every two days since withdrawal of water to the experiment. Seed weight (SW) was measured in triplicate before the beginning of the experiment. The Bartlett's and Levene's tests demonstrated (p > 0.05) normal distribution of the data. Using Gen-Stat and R software, ANOVA and post-hoc Tukey tests (p ≤ 0.05) were performed to examine the differences between the accessions across the seedling traits, days and MR. The findings revealed the significant difference (p < 0.05) in the traits in relation to the accessions, MR, and their interactions. Variation of the accessions on different traits as compared between the ST and NS experiments at day 7 was also proven significant. Through the ranking method, D349, D352, D363, D359, D147, HA4 and D348 were selected as the best drought tolerant (DT) accessions at seedling stage recommended for further assessment towards releasing the DT-high yield varieties potential in semi-arid conditions such as the central zone of Tanzania.