钾肥对镉的植物有效性的影响

Influence of Potassium Fertilizer on the Phytoavailability of Cadmium

采用室外盆栽模拟试验,研究了在镉单一污染及镉、铅复合污染的土壤中,钾肥(K2SO4)的施用及其施用水平对镉的植物有效性的影响.结果表明,施用钾肥可显著(p<0.05)促进小麦干重的增长,缓解重金属镉及镉、铅复合污染对小麦的毒害作用.不同施用水平的钾肥均减少了小麦对镉的吸收,降低了镉的植物有效性.随着钾肥施用水平的增加,小麦植株不同部位(根、茎叶和籽实)镉的浓度先逐渐降低而后上升,小麦植株不同部位的富集系数也呈现先降低而后上升的趋势,并且钾肥在K2水平时对镉的缓解效果最佳.施用钾肥降低了根际、非根际土壤交换态镉的含量,钾肥主要影响了小麦根际、非根际土壤中交换态、碳酸盐态镉的含量,而对铁锰氧化物结合态、有机质硫化物态和残渣态镉的影响较小.镉、铅复合处理与镉单一处理相比较,铅可促进小麦对镉的吸收,提高镉的植物有效性.

A field pot experiment was conducted to study the influence of potassium fertilizer （ K2SO4 ） on the phytoavailability of Cd in soils with single stress of Cd and combined stress of Cd and lab. Results showed that the application of K fertilizer could significantly （ p 〈 0.05 ） increase the dry weight of wheat and alleviate the toxicity of Cd and Pb. K fertilizer with different levels could decrease the uptake of Cd in wheat and the Cd phytoavailability in soils. With the increase of K fertilizer levels added, Cd contents and the enrichment coefficients of Cd in different parts （root,haulm and grain） of wheat decreased gradually at in＇st and increased later. It was suggested that at the K2 level, K fertilizer would alleviate the Cd toxicity efficiently. And the application of K fertilizer would reduce the exchangeable fraction of Cd in rhizosphere and bulk soils. It was also illustrated in this work that the contents of exchangeable and carbonate Cd in soils were affected most by the application of K fertilizer. However, the contents of Fe-Mn oxide, organic and residual Cd in soils were less affected. Comparing combined treatment of Cd and Pb with single treatment of Cd, Pb application would increase the uptake of Cd in wheat and the Cd phytoavailahility in soils.