硅素调理剂在镉超标菜地中的应用效果

Effect of Application of Silicon Amendment on Cd Over-Standard Soils of Vegetable Fields

【目的】探讨不同用量的硅素调理剂对镉超标菜地叶菜吸收镉和土壤镉有效性的影响作用,以明确施硅对土壤镉的调控效应,为合理利用硅素调理剂来减少叶菜镉含量提供参考。【方法】2009年在广州市郊镉超标菜地设置两个田间试验,研究硅素调理剂在4种施用水平下对土壤镉活性及叶菜吸收、累积镉的效应。【结果】硅素调理剂对镉超标菜地上菜心和生菜的增产效应不明显,但在用量为60 kg·667m-2时可显著增加两种叶菜体内硅含量,降低其镉含量;两种叶菜地上部硅含量分别比Si0处理增加了1.00和2.40倍,根系硅含量分别比Si0处理增加了0.95和2.37倍;在该用量水平下,两种叶菜地上部镉含量分别较Si0处理降低了25%和32%,根系镉含量较Si0处理降低了17%和15%。施用硅素调理剂后土壤DTPA-Cd含量较对照显著降低,#1菜地土壤pH较对照无明显变化,#2菜地土壤pH显著增加,但不同用量间差异不显著。【结论】适当施用硅素调理剂对降低叶菜体内镉含量效果显著,可以作为一种有效抑制镉超标菜地叶菜镉吸收的改良措施。

[Objective] The purpose of this study was to explore the effects of application of different amounts of silicon amendment on Cd uptake by leafy vegetables and soil available Cd concentration in cadmium over-standard vegetable field and to provide reference for proper use of silicon amendment to reduce leafy vegetable Cd concentration. [ Method ] Two field experiments were carried out to investigate Cd bioavailibity in soils and Cd accumulation by leafy vegetables under four levels of silicon amendment application in Cd over-standard fields in the suburbs of Guangzhou in 2009. [ Result ] The results showed that compared with the control silicon amendment insignificantly increased the output of flowering Chinese cabbage and lettuce grown in Cd over-standard soils, while shoot Si concentrations of flowering Chinese cabbage and lettuce significantly increased by 1.00- and 2.40-fold in the silicon amendment at 60 kg.667m^-2 treatment, respectively, and their root of Si concentrations increased by 0.95- and 2.37-fold, respectively. In comparison with the control, the silicon amendment at 60 kg.667m^-2 significantly reduced shoot and root Cd concentrations of flowering Chinese cabbage and lettuce, with shoot Cd concentration reducted by 25% and 32% and root by 17% and 15% respectively. Compared with the control, silicon amendment decreased soil DTPA-Cd concentrations significantly, and insignificantly affected soil pH of No. 1 vegetable field, but significantly increased soil pH of No. 2 with no significant differences between application levels.[ Conclusion]At the application level of 60 kg.667m^-2, silicon amendment could significantly reduce plant Cd content, and might be used as an effective soil amendment to inhibit Cd uptake by vegetables in Cd over-standard soil.