PJB-2025-443
EFFECTS OF CONSECUTIVE DROUGHT STRESS DURING ADJACENT GROWTH STAGES ON SOYBEAN MORPHO-PHYSIOLOGICAL TRAITS AND YIELD
Feifei Huang
Abstract
The increasing frequency, intensity, and duration of global drought stress have result-ed in a new phenomenon of consecutive drought events across adjacent growth stages, thereby intensifying the negative impacts on soybean growth, development, and yield. This study utilized a 2024 pot experiment with drought-stressed soybeans in China's Huaibei Plain, employing pairwise combinations of growth stages: seedling (S1), branching (S2), flowering-podding (S3), and seed filling (S4). Concurrently, three lower limits of soil moisture content were established: light drought (55% field capacity, FC), moderate drought (45% FC), and well-watered control (75% FC). A systematic evaluation was performed to assess soybean responses under the aforementioned drought treatment conditions. The results demonstrated that drought stress significantly reduced all parameters in treated groups compared to the normal irrigation group, with losses in-creasing with severity. Under drought stress, soybean exhibited maximal re-ductions in plant height (PH, 25.70%) and tap root length (TRL, 24.45%) at S1-S2, while the S2-S3 stage saw greatest decreases in primary branch number (PBN, 75.00%), root dry weight (RDW, 44.16%), and stem dry weight (SDW, 33.89%). The most severe im-pacts occurred at S3-S4, with grain yield (GY, 67.19%), total pod number (TPN, 49.82%), total seed number (TSN, 58.94%), and pod wall weight (PWW, 64.82%) showing maximal reductions, accompanied by the highest empty pod rate (EPR, 18.68%). Notably, GY showed strong positive correlations with RDW and pod traits (TPN, TSN, PWW), but negative correlation with EPR (p ≤ 0.001). These parameters accounted for 63.2% of the total variance in the first principal component (PC1) of soybean drought response traits. Thus, targeted irrigation during the S3-S4 stage is essential for mitigating drought-induced yield losses in soybean.
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