外源锌对水稻植株镉的累积差异分析

通过水稻威优46盆栽种植试验,研究了外源Zn施用(0,40,80,160 mg/kg 4个水平)对Cd中度(0.72mg/kg)和重度(5.26mg/kg)污染土壤中Cd生物有效性及水稻Cd累积的差异。结果表明:施Zn对各检测指标存在影响,但土壤Cd总量仍是土壤Cd活性和水稻Cd累积差异变动的主控因素。在Cd中度污染土壤中,施Zn降低了土壤交换态Cd含量1.9%~17.0%,但水稻根表铁膜、根和糙米中Cd含量随Zn施用浓度的增大而增大,糙米Cd含量从0.09mg/kg上升到0.17mg/kg,相关分析显示糙米Cd含量与土壤交换态Zn含量显著正线性相关。在Cd重度污染土壤中,施Zn增大了土壤交换态Cd含量2.1%~4.8%,但降低了水稻各部位中Cd含量,当施Zn浓度超过80mg/kg时,糙米Cd含量可从对照组的0.45mg/kg降低到0.12mg/kg,符合国家食品污染物限量标准(GB 2762-2017)的要求,相关分析显示糙米Cd含量与土壤交换态Zn含量显著负线性相关。对2种Cd污染程度的土壤,施Zn均可增大Cd在水稻地下部的累积率,从而降低水稻地上部Cd的累积率。在Cd重度污染土壤中,可通过施Zn降低糙米Cd含量,施Zn量80mg/kg是试验中最佳施用量;但在Cd中度污染土壤中,施Zn有增大糙米Cd含量的风险。

Diffident Analysis on Accumulation of Cadmium in Rice Plants with Zinc Application

The objectives of this study were to investigate the influences of different concentrations of zinc (Zn) application on cadmium (Cd) bioavailability in soil and Cd accumulation in rice grown in two Cd-polluted soils. Rice pot experiment was carried out and the rice variety was Weiyou 46. Application exogenous Cd and Zn,curing generated two Cd-polluted soil (0.72 and 5.26 mg/kg Cd) and four Zn-treated soil (0, 40, 80 and 160 mg/kg). Results showed that the application of Zn had an influence on the test indexes, while soil Cd concentration was the dominant factor affecting the soil Cd activity and the Cd accumulation in the rice plants. In the 0.72 mg/kg Cd treatment, the application of Zn reduced exchangeable Cd concentration in soil by 1.9%~17.0%, while increased the uptake and accumulation of Cd in the iron plaque, roots, and brown rice, the Cd concentration in brown rice was ranging from 0.09 to 0.17 mg/kg, furthermore, the Cd concentration in brown rice was linearly positively related to the exchangeable Zn concentration in soil. In the 5.26 mg/kg Cd treatment, the exchangeable Cd concentration in soil was increased by 2.1%~4.8%, the Cd concentration in various rice organs was decreased. Moreover, the Cd concentration in brown rice decreased to 0.12 mg/kg when the Zn concentration increased to 80 mg/kg, whereas it was 0.45 mg/kg at 0 mg/kg Zn, lower than the National Food Safety Standard of 0.2 mg/kg (GB 2762-2017). In addition, the correlations of the Cd concentration in brown rice and exchangeable Zn in soil were linear and negative. The experiment results also found that application of Zn increase the accumulation rate of Cd in the underground part of rice planed in two Cd-polluted soils, and then decreased the Cd accumulation rate of aerial part. A certain amount of Zn to reduce the Cd concentration in brown rice was feasible in the soil treated with 5.26 mg/kg Cd and the amount of Zn 80 mg/kg was the best applied in the experiment, while it increased the risk of Cd accumulation in the soil treated with 0.72 mg/kg.