连作对麦冬根际土壤细菌群落的影响

以中草药麦冬为研究对象,采用变性梯度凝胶电泳(DGGE)方法,考察连作对麦冬根际土壤细菌群落的影响。结果表明,重茬麦冬根际细菌群落的Shannon-Wiener指数从苗期至快速生长期、再到块根膨大期分别为3.36-3.40-3.69,丰富度指数为55.0-61.5-63.5,均匀度指数为0.84-0.82-0.89;而同期正茬根际细菌群落的上述指数值分别为3.66-3.33-3.72、67.5-53.5-63.5和0.87-0.84-0.90。通过对土壤细菌群落的DGGE图谱进行主成分分析,结果显示,上述各个时期重茬与正茬样本均发生显著分离,表明连作改变了麦冬根际细菌群落的多样性变化趋势和结构组成。进一步比较麦冬块根膨大期根际主要功能菌群的数量变化,发现连作后氨化细菌和好气性纤维素分解菌数量增加,而硝化细菌和固氮菌的数量减少。对比发现重茬麦冬的产量仅为正茬的70.6%,表明麦冬连作减产与其根际土壤细菌群落的变化相关。

The Effect of Continous Cropping to Soil Bacterial Community on Liriope Root

The continous cropping obstacle widely exists in cash crop cultivation, which usually result in a decline of the crop yield and quality. The origin of continous cropping obstacle is close related with the shift in soil environment, and the evolve of soil microorganism in continous cropping was important. This paper studied the effect of continous cropping on the rhizosphere bacterial using liriope (Liriope spicata var. prolifera Y. T.) as testing mertials. The diversity of liriope rhizosphere microbial communities was investigated by PCR-DGGE, the Shannon-Weaver indices of the continous cropping liriope rhizosphere microbial communities were 3.36-3.40-3.69 from seedling stage to rapid growing stage and to earthnut intumescentia stage, the richness indices were 55.0-61.5-63.5, the evenness indices were 0.84-0.82-0.89, those indices of normal liriope rhizosphere were 3.66-3.33-3.72, 67.5-53.5-63.5, and 0.87-0.84-0.90, respectively. The result shown that the trend of rhizosphere bacterial communities diversity variation in the continous cropping liriope was different with normal liriope. Furthermore, the Principal Components Analysis of DGGE profile of rhizosphere bacterial communities shown that the components of bacterial communities in continous cropping liriope were separated from normal liriope. That suggested continous cropping could alter the diversity variation trend and components of rhizosphere bacterial communities. Comparing the quantity of soil function bacteria at liriope tuberous intumescentia stage, the amount of amonifying bacteria and cellulose decomposition bacteria were increased while nitrobacteria and azotobacter were significant decreased after continous cropping. Besides, the yield of continous cropping was 70.6% of normal, it indicated that the decline in yield of liriope in continous cropping was related to the vary of soil bacterial community.