施用P肥对Cd污染胁迫下黄豆生长的调控作用

Regulating Effects of Phosphorus Application on the Growth of Glycine max Plants under Cd Contamination

通过红壤3个Cd处理水平(0、5、20mg·kg-1,以CdCl2形式加入)和5个P施用水平(0、20、40、80、160mg·kg-1,以KH2PO4形式加入)的黄豆盆栽试验,研究了P施用对土壤Cd污染胁迫下黄豆生长的调控作用.结果表明,在相同Cd处理水平下,随着P施用量的增加,土壤交换态Cd含量明显下降,最大下降量达到2.49mg·kg-1,黄豆根茎叶中Cd含量降低15.9%～32.1%,植株鲜重增加13.0%～31.4%;叶片Chl含量、SOD活性、MDA含量的变化也显示土壤Cd污染状况得到明显改善;并且,黄豆叶片生理指标、根茎叶Cd含量以及土壤交换态Cd含量之间存在着极显著的线性关系.但是P的施用不能完全消除土壤中不同Cd处理水平对黄豆生长造成的差异,还阻碍植株对Ca的吸收,说明P减轻土壤Cd对黄豆生物毒性的作用是有限的.

A pot experiment with treatments of 0, 5, 20 mg·kg^-1（in form of CdCl2） and 0, 20, 40, 80, 160 mg P2O5 · kg^-1（in form of KH2PO4） was conducted to study the regulating effects of phosphorus application on the growth of Glycine max plants under a condition of Cd contamination in red soil. The results indicate that, compared to the plants under various Cd contamination levels without phosphorus application, contents of soil exchangeable Cd decrease obviously with an increase in phosphorus application, and the greatest decrease of this Cd reaches 2.49 mg·kg^-1 that Cd contents in the roots, stems, and leaves of Glycine max plants decline by 15.9%-32.1%, fresh weights of the plants increase by 13.0%-31.4%, and chlorophyll （Chl） contents, SOD activities, and MDA contents in Glycine max leaves show apparent alleviations of soll Cd contamination situations due to the phosphorus application; and that there are significant linear relationships among the biomasses of Glycine max plants, physiological indexes （such as Chl contents, SOD activities, and MDA contents） in the leaves, Cd contents in the roots, stems, and leaves, and soil exchangeable Cd contents. However, phosphorus application does not eliminate completely the growth differences of Glycine max plants caused by different Cd contamination levels in soils and hinders the plants from taking in Ca, thus demonstrating only a limited relieving effect on the plants＇ Cd biological toxicity.