From Soil to Spikelet: The Integrated Impact of AWCI on Rice Growth Under Heat and Drought Stress

The intricate interplay among soil physicochemical properties, root physiological traits, and flowering gene expression fundamentally governs rice reproductive success and grain yield. This study elucidates the effects of the Aerobic and water-controlled irrigation (AWCI) method on rhizosphere soil parameters, root biochemical responses, pollen viability, and temporal expression of the circadian-related flowering gene OsFKF1 during the heading and flowering stage, illuminating their integrated impact on rice productivity. Application of the AWCI regime modulated soil pH and nitrogen dynamics at critical growth intervals, enhanced rhizosphere oxygen availability, and shifted redox potential, thereby optimizing nutrient bioavailability. Simultaneously, AWCI treatment influenced root antioxidant enzyme activities—including peroxidase (POD) and catalase (CAT)—as well as abscisic acid (ABA) and MDA concentrations, which positively correlated with elevated pollen viability and upregulated OsFKF1 expression. Multivariate analyses identified key determinants of yield enhancement, notably augmented root surface area during the jointing-booting phase, balanced soil nitrogen content, and finely regulated oxidative stress markers at the mid-tillering stage. Hierarchical clustering robustly designated the T ₃ treatment as the optimal AWCI protocol for maximizing reproductive performance and grain yield. Collectively, these findings underscore the pivotal nexus among irrigation management, soil biochemical milieu, root physiology, and floral gene regulation in modulating rice yield, offering a theoretical foundation for precision water management strategies tailored to sustainable productivity enhancement. Future research should extend to encompass additional flowering-related genes and a broader spectrum of rice cultivars to generalize these mechanistic insights.