The management of Cd in rice with biochar and selenium: effects, efficiency, and practices

Cadmium (Cd) contamination in paddy soil significantly threatens food safety and demands immediate attention in modern agriculture. The uptake of Cd by plant roots, facilitated by transporters involved in nutrient uptake, contributes to its accumulation in rice grains. To mitigate Cd accumulation in rice crops, reducing its bioavailability and controlling plant uptake is crucial. Various strategies, including the application of biochar and selenium (Se), have been proposed to address Cd toxicity in contaminated soils. Biochar and Se have effectively reduced Cd toxicity in rice crops through mechanisms such as Cd immobilization and sequestration in vacuoles. This review provides a comprehensive overview of past methods, such as chemical stabilization, and novel approaches, including biochar amendment, biochar modification, and Se-assisted Cd immobilization, in current research on Cd toxicity and its mitigation. Additionally, we examine the fate of Cd in paddy fields, Cd transport processes from soil to grains, and the adverse effects of Cd stress on rice plant growth, physiology, yield, and human health. The overall objective of this review is to enhance understanding of the environmental risks associated with Cd in rice ecosystems and the remediation effects of biochar and Se.