Determine drought tolerance levels in different soybean genotypes by assessing morphological, biochemical, and yield factors

Water scarcity and unexpected drought events are currently among the most significant abiotic stresses causing substantial losses in agriculture. Climate change has intensified unpredictable weather patterns, triggering unexpected drought spells on a global scale. Drought stress is a major factor contributing to significant yield losses in soybeans worldwide. Our experiment included four treatments: irrigation stopped at the flowering stage (T1), pod-setting stage (T2), and pod-filling stage (T3), along with a control group (T0) that received normal irrigation. We evaluated ten local and exotic soybean genotypes across three drought stages. The first treatment (T1) at the flowering stage showed relatively higher drought tolerance among the genotypes, likely because the plants had more time to activate their drought response mechanisms. However, the pod-setting stage (T2) was identified as the most sensitive to drought stress, leading to greater yield reductions. This highlights the critical nature of the pod-setting stage in soybean cultivation under water-limited conditions. Sensitivity towards drought was the highest in the pod setting stage despite it faced shorter drought period that flowering stage. Plant height and the number of branches had no significant impact on yield in this study and also significant difference for protein and oil content is very less and recorded in several genotypes. While T1 resulted in the shortest plants, seed yield and 1000-seed weight were lowest in T2 due to the high sensitivity of plants at that critical growth phase. This comprehensive analysis of parameters provided valuable insights for selecting soybean varieties best suited to local soil and water resources. Oil and protein content percentages were generally higher in control groups and affected negatively with increase in drought levels. Several genotypes showed significant reduction in oil and protein content while others showed non-significant differences. Based on these findings, farmers can make well informed decisions to choose varieties aligned with their specific needs and environmental conditions.