坡缕石钝化与喷施叶面硅肥联合对水稻吸收累积镉效应影响研究

采用盆栽试验,研究了坡缕石钝化与喷施叶面硅肥联合处理对水稻吸收累积Cd效应的影响。试验结果表明,单独喷施叶面硅肥能够增加水稻产量,可以不同程度地降低水稻地上部Cd含量及Cd从根系向地上部的转运能力。与空白对照相比,糙米、颖壳和秸秆中Cd含量最大可分别降低34.9%、30.1%和34.0%,且在水稻不同生育期喷施硅肥对Cd在地上部累积的抑制效果依次为分蘖期+齐穗期分蘖期齐穗期。盆栽试验中添加1.0%的坡缕石后能够显著降低土壤中Cd的生物有效性,糙米、颖壳、秸秆以及根系中Cd含量分别比空白对照降低39.5%、28.6%、35.3%和20.9%。坡缕石钝化处理并联合在水稻分蘖期和齐穗期分别喷施0.1%~0.4%叶面硅肥结果表明,钝化处理与叶面阻Cd联合能更加有效地降低水稻地上部对Cd的吸收,其中稻米、颖壳和秸秆中重金属Cd含量最大分别可降低58.1%、63.3%和68.7%,糙米中Cd含量可由对照的0.43 mg·kg-1降到低于稻谷Cd的食品安全国家标准限量值0.20 mg·kg-1以下,但对根系中重金属Cd的含量降低仅为17.8%,与坡缕石单一钝化相比无显著差异。

Effect of palygorskite immobilization combined with foliar silicon fertilizer application on Cd accumulation in rice

Pot experiments were conducted to investigate the effect of palygorskite immobilization combined with foliar silicon fertilizer application on cadmium accumulation in rice. The results showed that foliar application of Si obviously increased the dry weight of grain(with husk) and straw in rice grown in Cd contaminated soil, reduced Cd concentrations in grain, husk and straw and the Cd translocation to shoot, while Cd was more sequestrated in root. In comparison with the control treatment, the foliar application of Si led to a maximal decrease in the Cd concentrations of 34.9% for the grain, 30.1% for the husk and 34.0% for the straw, respectively. And from the foliar application period of Si, the order of Cd reduction effect was spraying Si at the tillering stage plus full heading period > tillering stage > full heading period. Pot experiments results showed that the application of palygorskite could increase soil pH, reduce the bioavailability of Cd in soil and Cd concentration in rice. The addition of palygorskite decreased Cd contents by 39.5% for the grain, 28.6% for the husk, 35.3% for the straw and 20.9% for the root compared with the control, respectively. In addition, the combined effect of foliar application of Si and palygorskite immobilization were more effectively on Cd accumulation in rice, Cd contents in grain were reduced from 0.43 mg·kg^-1 to less than national food safety standards of the rice cadmium 0.20 mg·kg^-1, and the Cd concentration in rice root, straw, husk and rice decreased by 17.8%, 68.7%, 63.3% and 58.1%, respectively.