[Variation in physicochemical properties and bacterial community structure in rhizosphere soil of Coptis chinensis tow cropping modes].

The natural forest and artificial shed are the main cropping modes of Coptis chinensis. This study is aimed to reveal the rhizosphere soil bacterial community structure difference between under tow C. chinensis cropping modes-natural forest and artificial shed, and to assist us to completely understand soil quality condition,and provide theoretical guidance for soil improvement and C. chinensis planting. The rhizosphere soil samples of 1-5-year-old C. chinensis under tow cropping modes-natural forest and artificial shed were collected. Illumina high-throughput sequencing technology was used to analyze the alpha diversity, community composition, community structure of soil bacteria under the tow cropping modes,and the effects of soil nutriment indices on soil bacterial community structure. Through the analysis of species number, Shannon, Chao1 index and ACE index of bacterial community, it was found that the bacterial diversity of 1-year-old C. chinensis soil under natural forest cropping mode was significantly lower than that under artificial shed cropping mode, and the diversity of bacterial communities in soil of 2-5-years old C. chinensis were not significant different between two cropping modes. A total of 53 phyla,60 classes,140 orders and 266 families were detected in the rhizosphere soil of C. chinensis under the cropping modes of natural forest, respectively. The rhizosphere soil of C. chinensis under the cropping modes of artificial shed included 54 phyla,65 classes,140 orders and 264 families, respectively. Under the two cropping modes, the top 10 dominant species of bacterial community abundance are the same, they are Proteobacteria, Acidobacteria, Actinobacteria,Bacteroidetes, Planctomycetes, Chloroflexi, Verrucomicrobia, Gemmatimonadetes, Firmicutes and Cyanobacteria, but there are differences in the abundance sequence. The top 10 dominant species of bacterial community abundance accounted for 74.36% to 74.30% of the total bacteria, and 3.15% to 3.92% of the bacteria are unclassified. The results of Metastat analysis showed that the abundance of Gemmatimonadetes in the rhizosphere soil of C. chinensis under the cropping modes the artificial shed was significantly higher than that under the natural forest cropping mode(P<0.05). MRPP analysis of community structure differences showed that under tow cropping modes, there were significant differences in the bacterial community structure of 1-4-year-old soil bacteria, among which the difference between 1-year-old soil samples was the largest. With the increase of cropping years, the difference gradually decreases, and there is no significant difference in the bacterial community structure between 5-year-old soil samples. RDA analysis and correlation analysis of bacterial community structure and soil physical and chemical properties showed that the order of environmental factors on the rhizosphere soil bacteria of Coptis chinensis was: pH>available P> total P> total K>bulk density>total N>available N>organic matter. The results are helpful to understand the soil health of C. chinensis and provide scientific basis and theoretical guidance for soil improvement and C. chinensis planting.