土壤与基质栽培系统对生菜(Lactuca sativa)根际细菌群落的影响

以生菜（Lactuca sativa）“申选5号”与“罗莎红”为材料，采用PCR-DGGE 和Real-Time PCR 技术，分析了土壤栽培系统和基质栽培系统根际细菌群落的差异。Real-Time PCR 检测结果表明，基质栽培的两个生菜品种根际细菌数量均显著高于土壤（P<0.05）；PCR-DGGE图谱条带结果表明，根际细菌群落多样性基质高于土壤。栽培系统是造成多样性差异的主要原因，但也与品种有关：“申选5 号”基质的Shannon-Wiener 指数（H），Simpson 指数（D）和均匀度（E）均显著高于土壤（P<0.05）；“罗莎红”基质的H 显著高于土壤，而D和E 无显著差异。结合土壤和基质理化性质的RDA 分析结果，土壤和基质具有不同的细菌群落，pH 值与硝态氮是塑造根际细菌群落的主要因子，含水量、碳氮比和有效磷与细菌群落的形成呈正相关。

Effects of Soil and Substrate Cultivation on Lettuce Rhizosphere Bacterial Community

Rhizosphere bacterial community can promote the nutrition absorption of plant root, which result in the upgrade of plant quality. Cultivation system has effect on rhizosphere bacterial community. Four treatments were set to investigate the effects of two different cultivation systems, soil and substrate systems, for two varieties of lettuce, Shengxuan NO.5 and cv. Lollo Rossca.(two cultivation systems × two varieties). Each treatment had three pots as samples with 10 lettuce plants for each pot. After 30 days of transplanting, five plants of each pot were randomly selected, and rhizosphere soil or substrate was sampled. Real-time PCR and PCR-DGGE were implied to analyze the characteristics of rhizosphere bacterial community in each treatment. Real-Time PCR detection showed that the number of the population of rhizosphere bacteria in substrate system was significantly higher than that of soil system(P<0.05). PCR-DGGE profiles revealed that the diversity of substrate system was significantly higher than that of soil system. As for Shenxuan NO.5, the Shannon-Wiener index(H), Simpson index(D)and Pielou evenness index(E)of substrate system were significantly higher than that of soil system(P<0.05), and for cv.Lollo Rossca, index H of substrate system were significantly higher than that of soil system(P<0.05). RDA revealed that soil and substrate systems had different bacterial communities, and pH and nitrate nitrogen were two main factors that determining the community structure. In addition, water content, C/N, and available phosphorus were positively correlated with the development of bacterial community. Overall, soil and substrate cultivation systems had different rhizosphere bacterial community, and the quantity and diversity were higher in substrate system due to the physiochemical difference.