磷对镉胁迫下黄豆生理生化特性的影响

Effects of Phosphorus on the Physiological and Biochemical Properties of Soybean(Clycine max) under Cadmium Stress

采用盆栽试验方法,选取5个磷质量浓度(0,20,40,80,160mg/kg)和3个镉质量浓度(0,5,20mg/kg),研究了镉和磷共同作用对黄豆叶片叶绿素含量、超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量的影响,同时探讨磷作用下缓解镉毒害的途径.结果表明,镉的加入阻碍黄豆的生长,随着镉浓度的提高,叶绿素含量和SOD活性明显下降,而MDA含量则显著上升.添加磷在一定程度上可以提高叶绿素含量和增加SOD活性,降低MDA含量.在本试验条件下,镉为5mg/kg时,磷的最佳施用量为80mg/kg,高磷(160mg/kg)处理的植株,其各项生理指标不如80mg/kg磷处理组,说明在镉污染土壤中施用磷,磷浓度并非越高越好.而在镉为20mg/kg时,磷的最佳添加量为160mg/kg.

A pot experiment on soybean growth at different cadmium and phosphorus levels was conducted. The soybean was cultured at three levels of cadmium （0, 5, 20 mg/kg） and five levels of phosphorus （0, 20, 40, 80, 160 mg/kg） to investigate complex effects of cadmium and phosphorus on chlorophyll contents, SOD（superoxide dismutase）activities and MDA （malondialdehyde）contents in soybean leaves. And the experiment was also designed to discuss new ways to mitigate the toxicity of cadmium through phosphorus application. The results showed that cadmium addition inhibited growth of soybean; phosphorus application in the soil, however, counteracted the growth inhibition caused by cadmium to some extent. With increasing cadmium levels, chlorophyll contents and SOD activities decreased remarkably, and MDA contents increased significantly. Phosphorus application could, to some extent, heighten chlorophyll contents and SOD activities and depress MDA levels. In this experiment, 80 mg/kg was the best application amount of phosphorus to the soil polluted with 5 mg/kg cadmium, and 160 mg/kg was the best application amount to the soil polluted with 20 mg/kg cadmium. So application of excess phosphorus （160 mg/kg） showed not to be more effcctive than others in the alleviation of cadmium toxicity to soybean.