不同连作茬次黄瓜根际土壤微生物群落的T-RFLP分析

T-RFLP analysis of cucumber rhizosphere microbial communities in different cropping seasons

以不同连作茬次黄瓜根际土壤为研究对象,利用末端限制性片段长度多态性(TRFLP)技术研究了土壤细菌、真菌菌群结构的动态变化。结果表明,黄瓜种植后各时期土壤细菌群落多样性指数大体呈先降低后升高的趋势,第7茬达到最低;黄瓜种植后50 d,真菌的多样性指数从第3茬到第9茬,呈先降低后升高的趋势,在第7茬达到最高,与种植30、40 d变化趋势相反。细菌优势菌群的种(属)数量到第7茬下降到最低,第9茬又上升,各茬次细菌出现的优势菌群主要是梭菌纲、γ-变形菌纲、α-变形菌纲以及一些未知菌群。真菌优势菌群种(属)数量第7茬上升最高,第9茬又下降,各茬次真菌出现的优势菌群主要是丝孢纲、外生菌根真菌、接合菌纲、伞菌纲、担子菌纲及一些未知真菌。同时,黄瓜生长时期对土壤细菌和真菌菌群结构的影响大于连作茬次的影响。总之,连作改变了土壤细菌和真菌的菌群结构及多样性水平,第7茬黄瓜根际土壤细菌、真菌群落与其他茬次明显不同。

In this paper, the dynamic changes in bacterial and fungal community structures in the rhizosphere of cucumber in different cropping seasons were analyzed with the terminal restriction fragment length polymorphism （T-RFLP） method. Results showed that the diversity index of bacterial community decreased from the first to the seventh cropping season, and then increased in the ninth cropping season. At 50 days after sowing, the diversity index of fungal community increased from the third to the seventh cropping season, and then decreased in the ninth cropping season, which was in contrast with the trends observed at 30, 40 days after sowing. The number of predominant bacterial species decreased from the first to the seventh cropping season and then increased in the ninth cropping season, and the predominant species mainly included classes such as Clostridia, ～-Proteobaeteria, oL-Proteobacteria and unknown bacteria. The number of predomi- nant fungal species increased from the first to the seventh cropping season, then decreased in the ninth cropping season, and the predominant species mainly included Hyphomycetes, ectomycor- rhizal fungi, Zygomycete, Agaricomycetes, Basidiomycetes and unknown fungi. Moreover, the influence of cucumber growth stages on soil bacterial and fungal community structures was stron- ger than that of cropping seasons. In conclusion, continuous cropping changed the cucumber rhizosphere bacterial and fungal community structures and diversities. Especially, the bacterial and fungal community structures in the seventh cropping season were obviously different from those in the other cropping seasons.