Toxicity of Cadmium on Different Rice Genotypes

To understand the differences between rice genotypes in cadmium (Cd) tolerance, pot soil experiments were conducted with two rice genotypes at different soil Cd levels, i.e. 0 (the control), 10, 50 mg kg^-1. The results showed that the two rice genotypes were tolerant to the soil Cd level of 10 mg kg^-1, but the soil Cd concentration of 50 mg kg^-1 was an effective soil Cd level that inhibited rice growth and reduced rice grain yield. The genotype Indica was more sensitive to soil Cd stress than the genotype Japonica, especially in root growth. Rice roots were more sensitive to soil Cd stress than shoots and grains. So the response of root to Cd stress may serve as a potential indicator of rice cultivars and genotypes in Cd tolerance. The toxicity of Cd on rice growth had accumulative effects in earlier stages of rice growth as the prolonging of Cd stress on rice plants, but some adaptations and growth compensations to Cd stress may occur in rice plants at later growth stages.