The Effect of Continous Cropping to Soil Bacterial Community on Liriope Root
连作对麦冬根际土壤细菌群落的影响

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.