Abstract: The bacterial colonies of soil samples were analyzed by PCR-DGGE technique in order to provide theoretical basis for controlling obstacles of tobacco continuous cropping. The results showed that soil bacterial community was rich in flue-cured tobacco mid-late growing period. There were differences in the structure of bacterial community in field soil by different continuous tobacco cropping, most of the bacterial types were common, and there were few unique bacterial types. The change of bacterial abundance in continuous cropping soil was very stable, and the continuous cropping increased the abundance of soil bacteria, and showed a tendency of firstly increasing and then decreasing. The dominant populations of rotation bacteria were stable in the field period, while the bacterial flora in continuous cropping soil had greater changes. The activities of bacteria in warm-curvae, acid bacillus door and corynebacteriaceae had strong impact on soil nutritional metabolism, the pathogens were increased, which was unfavorable for the growth and development of flue-cured tobacco. Different continuous cropping years had greater impacts on the soil bacterial population structure in flue-cured tobacco. The changes in bacterial population structure of flue-cured tobacco after continuous cropping could be one of the main reasons causing obstacles in flue-cured tobacco continuous cropping.

Key words: flue-cured tobacco, continuous cropping, rhizosphere soil, bacterial communities, PCR-DGGE

摘要： 以不同连作年限烤烟根际土壤为材料，应用PCR-DGGE技术对土壤样品进行细菌菌落分析，以期为烟草连作障碍调控提供理论依据。结果表明：烤烟生育中后期土壤细菌群落比较丰富。不同连作年限植烟土壤大田期细菌种群结构有差别，表现为大多数细菌类型是共有的，存在少数特有的细菌类型，轮作土壤的细菌丰度变化较稳定，而连作增加了土壤细菌的丰度，并呈先增加后降低趋势。轮作细菌优势种群在大田期很稳定，而连作土壤的细菌菌群有较大变化，绿弯菌门的暖绳菌科、酸杆菌门和棒状杆菌科的菌群活动对连作土壤的营养代谢有强烈的影响，致病菌增多，不利于烤烟生长发育。不同连作年限对烤烟根际土壤细菌群落有较大影响，烤烟连作后细菌种群结构的变化可能是引发烤烟连作障碍的主要原因之一。

关键词: 烤烟, 连作, 根际土壤, 细菌群落, PCR-DGGE