低含量Pb对Cd处理下冬小麦幼苗根际微生物群落的影响*

采用Biolog Eco微生物分析法,分析了土壤盆栽试验条件下低于国家"土壤环境质量标准"规定的Ⅱ类土壤环境基准值每kg干土350 mg(土壤pH>7.5)的Pb对Cd处理下冬小麦幼苗根际土壤微生物群落的影响特征.结果表明:土壤Pb含量低于国家土壤环境基准值时,会显著影响Cd对冬小麦幼苗根际土壤微生物碳源利用率、代谢功能多样性指数及群落结构的影响特征,主要表现为土壤低含量Pb增强了Cd对微生物利用不同碳源能力的抑制效应,同时亦加强了Cd对微生物代谢功能多样性指数的影响特征;冬小麦幼苗根际土壤微生物代谢功能多样性指数与根系分泌物酚酸和简单糖类之间的相关性特征在低含量Pb-Cd处理与Cd处理之间明显不同,且相关方向和显著性水平均发生了明显变化.

Effects of Low Lead Content on the Microbial Community in the Rhizosphere of Winter Wheat Seedlings under the Stress of Cadmium

The Biolog Eco method was used to investigate the effect of low lead content (< 350 mg?kg-1 dry weight soil, soil pH > 7.5) on the rhizosphere microbial community of potted winter wheat seedlings under the stress of cadmium. The low lead content significantly results in the shift of rhizosphere carbon source utilization of microorganisms, microbial metabolic diversity indexes, and microbial community structure in the stress of cadmium. And it mainly strengthens the inhibition of cadmium on the ability of the rhizosphere microbes to utilize different carbon resources, meanwile it enhances the effect of cadmium on the microbial metabolic diversity. Furthermore, the correlation between rhizosphere microbial metabolic diversity indexes and the content of simple sugars and phenolic acid exudates under Pb Cd is obviously different from that under Cd, and the correlation direction and the significant level all change evidently.