不同程度重金属污染土壤对东南景天根际土壤微生物特征的影响

    通过盆栽试验研究不同程度重金属污染土壤对2种生态型东南景天根际土壤微生物特征的影响.研究结果表明,不同污染土壤中,2种生态型东南景天根际细菌、放线菌和真菌的数量及微生物生物量碳都大于非根际.在轻污染土壤中,2种生态型东南景天的根际土壤微生物区系和主要生理类群没有显著差异,而在矿山土壤和重污染土壤中,超积累生态型东南景天根际土壤中的细菌和真菌数量、主要生理类群数量及微生物生物量碳显著高于非超积累生态型.东南景天根际微生物对重金属胁迫的敏感性为放线菌＞细菌＞真菌,硝化细菌＞自生固氮菌＞氨化细菌＞磷细菌＞纤维分解菌.在轻污染土壤中,2种生态型东南景天根际土壤基础呼吸速率和微生物代谢商差异不显著,而在矿山土壤和重污染土壤中,非超积累生态型东南景天的根际土壤基础呼吸速率和微生物代谢商显著高于超积累生态型.

Effects of heavy metal-contaminated soils at different levels on rhizosphere microorganisms of Sedum alfredii Hance

Pot experiments were conducted to study the effects of heavy metal contaminated soils at different levels on soil microbial characteristics of two contrast ecotypes of S.alfredii Hance.The results show that in different soil,populations of bacteria,actinomycetes and fungi and microbial biomass C in rhizospheric soil of S.alfredii Hance were much greater than that in non-rhizospheric one.In slightly polluted soil,there was no significant difference on soil microflora and major microbial physiological groups between the two ecotypes of S.alfredii,whereas in mining soil and seriously polluted soil,populations of bacteria and fungi,physiological groups and microbial biomass C in the rhizospheric soil of the hyperaccumulating ecotype of S.alfredii were much greater than that in non-hyperaccumulating ecotype.The order of soil microorganisms being sensitive to heavy metal pollution was actinomycetes>bacteria>fungus,and nitrobacteria>azotobacteria >ammonifying bacteria>phosphobacteria>cellulose decomposing bacteria.No significant difference on soil base respiration and soil microbial metabolic quotient between the two ecotypes was observed in slightly polluted soil,however,this two indexes in the rhizosphere of non-hyperaccumulating ecotype were much greater than that of hyperaccumulating ecotype in mining soil and seriously polluted soil.