In order to find out the relationship between continuous cropping barriers and soil microbial communities,this research studied the mechanism of soybean continuous cropping obstacles from the ecological view of soil microbial community,the soil and rhizosphere soil of soybean in full flowering period of soybean stubble and continuous cropping for 4,6,8 and 10 years were taken as the research objects,the 16S/18S rDNA PCR-DGGE method was used to study the characteristics of soil and rhizosphere in full flowering stage of soybean,the population structure of bacteria and fungi in different years of continuous cropping soil were compared,and the differential electrophoresis bands were sequenced and compared.The results show:cluster analysis shows soil is clustered in one cluster and rhizosphere soil in another cluster,the community structure of bacteria and fungi is obviously different from that of rhizosphere soil.The DGGE map of 16S rDNA showed that there was no obvious change in the soil bacterial community,but there was obvious change in the rhizosphere bacterial population.The sequence alignments showed that most of them were Proteobacterium,which was a kind of nitrogen-fixing bacteria.The DGGE map of 18S rDNA showed that there were some differences and changes in the fungal structure among the treatments,and some bands appeared or disappeared in different treatments,the sequence alignments showed that most of the fungi with great variation were Trichosporon pullulans,Temellomycete,Phoma sp.,Cladosporium cladosporioides,Trichosporon pullulans and Cyathus striatus.Results showed that the rhizosphere effect of bacteria and fungi was obvious,and the change of bacterial population in soybean soil was not obvious,and it had great effect on the structure of fungal population.The results can provide scientific basis for the mechanism of soybean continuous cropping obstacle.
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