[Provoking Effects of Exogenous Zn on Cadmium Accumulation in Rice]

Pot experiments were carried out to study the influences of different concentrations of exogenous Zn on accumulation of Cd in various rice organs of low Cd accumulation cultivar Xiang-Wanxian 12 (XWX12) and high Cd accumulation cultivar Wei-You 46 (WY 46) exposed to soil with medium and serious Cd pollution. The results showed that:In the soil with medium Cd pollution, Cd contents in various rice organs of two rice varieties were increased by exogenous Zn, and the Cd contents in brown rice of XWX12 and WY46 were increased by 125.0% -275.0% and 6.6% -91.2%, respectively, but still lower than 0.2 mg·kg^-1. In the soil with serious Cd pollution, Cd accumulation in various rice organs were reduced by exogenous Zn. Cd contents in brown rice of XWX12 and WY46 were reduced by 16.6%-63.5%, and 15.6%-74.4%, respectively, and Cd contents in brown rice of WY 46 were gradually decreased with increasing exogenous Zn application, resulting in lower than 0.2 mg·kg^-1 of Cd in brown rice. The correlations of Cd contents in brown rice and exchangeable contents of Cd and Zn in soil were different depending on the Cd pollution levels and the rice varieties. In the soil with medium Cd pollution, Cd content in brown rice of XWX12 was linearly positively related to exchangeable Zn content in soil, and Cd content in brown rice of WY46 was linearly positively related to exchangeable Cd or Zn contents in soil. In the soil with serious pollution, however, the correlation of Cd contents in brown rice of WY46 and the contents of exchangeable Cd or Zn in soil was linear negative correlation. Therefore, for improvement of the rice quality, under the condition that total Zn content in soil was lower than the pollution level, applying a certain amount of Zn to reduce Cd contents in brown rice was feasible in the soil with serious pollution.