中微量元素和有益元素对水稻生长和吸收镉的影响

采用盆栽试验，研究了中微量元素和有益元素对水稻生长和吸收镉的影响。结果表明，在所有测试的元素和施用方法中，硅酸钠叶面喷施显著增加稻谷产量，而碳酸钙、硼酸、硅酸钠土施和亚硒酸钠显著降低了稻谷产量。镁、锌、铁的盐酸盐形态对水稻籽粒的增产效果优于硫酸盐形态，而钙、铜的硫酸盐形态增产效果略高于盐酸盐形态。在钙、镁、硫三种中量元素中，钙增加了水稻籽粒中的Cd浓度和吸收量，而镁和硫则降低了籽粒中的Cd浓度和吸收量，以硫磺粉处理为最低。稻草中的Cd浓度和总量均以氯化镁处理为最高，硫磺粉处理最低。镁能有效抑制Cd从秸秆向籽粒的转移，其盐酸盐优于硫酸盐。在微量元素中，锌对水稻Cd的吸收抑制作用最为显著，其次是铜，而有益元素肥料硅酸钠叶面喷施则显著增加了稻谷中的Cd浓度和吸收量。硫酸亚铁、氯化锰、氯化铜、硼酸和硼砂处理都能有效地抑制Cd从秸秆向籽粒的转移，而硅酸钠叶面喷施和锌处理则促进了Cd的转移，表明硅酸钠抑制水稻吸收Cd的机制很可能发生在土壤中，而非在植株体内或地上部分。在Cd污染土壤上选用适宜的中微量和有益元素肥料及其施用方法，能有效降低水稻对镉的吸收和稻米中的Cd含量。

Effects of secondary, micro- and beneficial elements on rice growth and cadmium uptake

Effects of secondary, micro- and beneficial elements on rice growth and cadmium (Cd) uptake were investigated in a pot experiment. The results showed that folia application of sodium silicate significantly increased rice grain yield, while calcium carbonate, boric acid and sodium silicate incorporated into soil significantly reduced rice grain yield. The chloride forms of magnesium (Mg), zinc (Zn) and iron (Fe) were more favorable to enhance rice grain yield than the sulfate salts of the three elements, while the sulfate forms of calcium (Ca) and cupper (Cu) just behaved in an opposite manner. Among the three secondary elements of Ca, Mg and sulfur (S), Ca enhanced but Mg and S in particular reduced the concentrations and uptake of Cd in grain. In straw, the concentrations and uptake of Cd were minimized by magnesium chloride and S in particular. It was found that Mg retarded transferring Cd from straw to grain, with magnesium chloride more effective than the magnesium sulfate. Among the micro-elements studied, Zn was most effective in blocking Cd uptake by rice, and followed by Cu, while folia application of the beneficial element of Si as sodium silicate topped the all the treatments in concentrations and uptake of Cd in grain. The treatments of ferrous sulfate, magnesium chloride, cupper chloride, boric acid and borax effectively depressed but the treatments of Zn and folia application of sodium silicate promoted the transfer of Cd from straw to grain, indicating the mechanism of Si blocking Cd uptake by rice was most likely to occur in soil rather than within plant or in the aboveground portions of the plant. It implies that selecting appropriate forms of secondary, micro- and beneficial elements and using proper application methods could effectively reduce Cd uptake by and Cd content in grain in the Cd polluted soil.