Effect of silicon amendment on soil-cadmium availability and uptake in rice grown in different moisture regimes

Greenhouse experiments were conducted to study the effects of silicon on soil-cadmium availability and uptake in rice grown in an acid soil maintained under two different moisture regimes (field capacity or submergence). The silicon treatment decreased the cadmium concentration and uptake in grain and straw, while it increased the cadmium uptake in roots of plants grown on cadmium contaminated soil. Cadmium availability in soil decreased with increase in silicon applied in soil due to the rise in soil pH. The results suggest that the reduction of soil-cadmium availability could be due to cadmium immobilization caused by calcium silicate-induced pH rise in the soils. The decrease in cadmium concentration and uptake in grain and straw could be attributed to the silicon-mediated distribution of cadmium that resulted in the increased accumulation of toxic cadmium in the roots more than the edible parts of the rice plants.