黄瓜连作土壤微生物区系变化研究

研究了黄瓜根部土壤主要微生物类群随连作茬次的反应,并着重用变性梯度凝胶电泳(DGGE)监测黄瓜根际未培养优势菌群的动态变化。结果表明:随着连作茬次增加,土壤可培养微生物数量减少,其中细菌数量降低更为明显,对连作表现出较高的敏感性,放线菌对黄瓜连作反应稍滞后,至第三茬时开始呈现降低趋势。黄瓜连作致使少数真菌种群富集,同时多种真菌类群数量减少,种群变化呈现单一化趋势,多样性水平降低。DGGE分析结果表明黄瓜连作引起根际Bacillus sp.、Pseudom onas sp.和另一未培养细菌种群数量减少,而同时引起Sphingom onas sp.类群数量增加。实验结果暗示,黄瓜连作破坏根部微生物种群生态平衡,使其多样性水平降低。

Variation of Microbial Community Structure in Relation to Successive Cucumber Cropping Soil

Reaction of dominant microbial communities to successive cropping times as well as the uncultivable microbial dynamics occurred in cucumber root soil were investigated by both plate count following identification and DGGE technique.Results revealed that the number of cultivable microorganism reduced along with successive replant times increasing.Of the shifted microorganism,bacteria population showed a drastic variation,which indicated that it was more sensitive to successive cropping.Compared with bacteria,actinomycetes had a lagging reaction whose number began to fall at the third cropping times.Successive cucumber plant could enrich minor fungi species and reduce many ones as well.Fungi population presented a single tendency and lower species diversity.The sequenced DGGE bands indicated that cucumber replant resulted in Sphingomonas,Pseudomonas and another uncultured bacteria specie increase in number while Bacillus genus decrease at the same time.The experiment indicated that cucumber replant destroyed the microorganism balance and decreased its diversity in roots soil.