干旱胁迫对棉花幼苗生长的抑制机制：光合限制与激素响应的动态解析

his study used the upland cotton variety "Guoxin Cotton No. 9" as the experimental material and set up three treatments: normal water supply (CK), moderate drought (MD), and severe drought (HD). The morphological characteristics, photosynthetic properties, antioxidant systems, and hormone responses of cotton seedlings were analyzed over a period of 0-28 days. The results showed that: (1) Drought stress significantly inhibited cotton growth, with plant height, leaf area, and dry biomass significantly decreasing under HD compared to CK; (2) Photosynthesis was regulated by both stomatal and non-stomatal limitations, with MD primarily dominated by stomatal limitation and HD by non-stomatal limitation; (3) Hormonal dynamic balance was a key response mechanism, where ABA accumulation triggered stomatal closure and GA content reduction likely inhibited growth; (4) Reactive oxygen species (ROS) metabolism imbalance exacerbated cellular damage, with significant increases in H?O? content and relative conductivity under HD. In summary, cotton responded to drought stress through morphological and physiological coordination, but severe stress may cause irreversible damage. These findings provide a theoretical basis for elucidating the drought resistance mechanisms of cotton and developing water-saving cultivation strategies.