Effect of Mixed Spraying of SA and ABA on the Growth and Development of Winter Oilseed Rape (Brassica napus L.) During the Post-Waterlogging Podding Period

Winter oilseed rape is particularly vulnerable to waterlogging stress during its growth and development stages, especially at the podding stage, leading to impaired photosynthesis, reduced antioxidant enzyme activity, and significant declines in yield and oil content. Previous studies have demonstrated that exogenous plant growth regulators, such as salicylic acid (SA) and abscisic acid (ABA), enhance crop resistance to abiotic stresses. Nevertheless, their combined application for winter oilseed rape recovery under waterlogging stress remains underexplored. In this study, a pot experiment was conducted to investigate the effects of SA, ABA, and their combination on the growth, photosynthesis, antioxidant enzyme activity, and yield of winter oilseed rape at the podding stage following waterlogging stress. The results showed that mixed spraying of SA and ABA significantly improved plant height, effective branching number, yield per plant, and thousand-grain weight of winter oilseed rape, surpassing the effects of individual treatments. Structural equation modeling revealed that mixed spraying enhanced yield components through direct improvements in photosynthesis and indirect regulation of antioxidant enzyme activities. This study is the first to systematically evaluate the role of mixed spraying of SA and ABA in mitigating waterlogging stress and restoring yield and quality in winter oilseed rape. This approach effectively alleviates the adverse effects of waterlogging and provides a valuable reference for post-waterlogging management of other crops. These results hold significant implications for addressing the impacts of climate change and ensuring global food security.