Optimizing water management for cadmium mitigation in rice production: A global meta-analysis and application effectiveness assessment.

Cadmium (Cd) contamination in rice poses a global threat to public health. Water management is recognized as an efficient and cost-effective strategy for reducing rice grain Cd concentration. A global meta-analysis was conducted to evaluate the effects and underlying mechanisms of water management on Cd concentration in rice, and an application effectiveness assessment was further established. The present results showed that flooding during rice grain-filling stage alone significantly decreased grain Cd concentration by 66.81 %. The tillering stage was identified as a critical period for early Cd uptake and redistribution in rice. Mechanistic analysis revealed that flooding limited Cd absorption by regulating sulfur and iron cycle, enhancing iron plaque formation, and suppressing the expression of Cd transporter genes (OsNRAMP1 and OsNRAMP5) in rice root. Moreover, the combination of water management and exogenous amendments formed a synergistic strategy for decreasing grain Cd concentration but increasing grain yield. The application effectiveness assessment showed that the combination of adsorptive amendments and antagonistic fertilizers could generate economic benefits of 8972 Chinese Yuan (CNY) and 7990 CNY per hectare, respectively. Monte Carlo simulations indicated that synergistic strategy also significantly lowered the hazard quotient and carcinogenic risk, thereby reducing human health risks associated with dietary Cd exposure. Overall, this study clarified the role of water management in Cd migration in the soil-rice system. The application effect of the combination of water and exogenous amendments was further evaluated, which provided guidance for global rice safe production.