Dual soil-rice interventions of silicon-selenium-calcium composites mitigate cadmium and arsenic accumulation in rice grains.

This study aims to evaluate the effectiveness of selenium, silicon, and calcium in reducing the accumulation of cadmium (Cd) and arsenic (As) in rice, and to explore their synergistic mechanisms. Field experiments were conducted by applying multi-nutrient composite materials (MCM) to rice plants. Environmental health risk assessment, soil pH, Cd and As content in rice grains, iron plaque, and the activity of antioxidant enzymes were measured to evaluate the effectiveness of MCM. The application of MCM significantly reduced the Cd and As concentration in rice grains by 56.76% and 84.75%, respectively. Moreover, MCM reduced the health risks of rice. Soil pH increased from 5.93 to 6.44, reducing the Cd and As bioavailability. Iron plaque formation increased by 60.36-230%, creating a barrier against Cd and As uptake. The increase in available silicon and calcium restricts rice uptake of both Cd and As. MCM promoted the Cd and As accumulation in vacuoles and cell walls, reducing their translocation in rice root, stem and leaf, while enhancing antioxidant enzyme activity. MCM effectively reduces Cd and As accumulation in rice through the synergistic effects of selenium, silicon, and calcium, providing a viable solution for rice safety.