The Soil Fungal Diversity Analysis Of Tobacco Fieldsin XiangxiAutonomous District

Tobacco mono cropping obstacle often referred to the phenomenon that tobacco plants which were under the mono cropping showed plant growth retardation, stunted, yield and quality reduction, and soil borne diseases damage aggravation. At present, there is a large area of tobacco mono cropping in China, the mono cropping obstacle crisis cause the direct and indirect economic losses of 4 billion every year. Strengthening the research on the mechanism of mono cropping of tobacco, then reduce and avoid the loss caused by mono cropping, has important economic and social significance to the development of China and the global tobacco industry.In this study, the tobacco is cultivated in three areas of Xiangxi, Hunan Province, Analysis the diversity of different ages of tobacco rhizosphere microbial community structure of three regions by using High Throughput sequencing method. Selective culture medium is used to isolate and count the rhizosphere bacteria and fungi in soil samples, to discover changes in the rhizosphere microbial community of tobacco in different areas of different degrees of disease. The results show, different rotation system, the four group of microbial diversity and evenness in onset period were significantly decreased, the diversity of mono-cropping and corn rotation was higher than that of Lily rotation and radish rotation, but the incidence of mono cropping and radish was the highest, in the 7 years of mono cropping, the number of species in the onset period was higher than that in the winter fallow period, and increased with the increase of mono cropping years; Application of different green manure, the number of species in onset period is lower than the winter fallow period. Diversity and evenness of fungal communities in applying pea green manure group was higher in onset period than that of the winter fallow period, the other three groups were higher in winter fallow period. Microbial diversity and evenness in control group was the highest, and uniformity of pea green manure was the lowest. The incidence rate in ryegrass and pea green manure group is the lowest. The results show that, the tobacco planting will reduce fungal species richness and diversity, there is no relation between the diversity of fungi and the incidence of tobacco, and there is no direct link between the diversity of fungi and the incidence of tobacco.It has been found that the number of culturable bacteria and culturable fungi is different under different rotation systems. The number of culturable bacteria in the rotation of tobacco-corn is the most, reaches 9.38×107CFU/g dry soil, and the number of culturable bacteria in tobacco-radish rotation is the least,1.15×107CFU/g dry soil. The number of culturable fungi(high to low) in 4 rotation systems of radish is tobacco-radish, tobacco mono-cropping, tobacco-lily, and tobacco-corn. The number of culturable bacteria in mono-cropping 4 years is the most, reaches 8.31 × 107CFU/g dry soil, and the least number of culturable bacteria is the mono-cropping 12 years,1.31×107CFU/g dry soil. The number of culturable fungi in mono-cropping 12 years is the most, reaches 8.06×10~4CFU/g dry soil, and the least number is the mono cropping 4 years,2.15×10~4CFU/g dry soil. Application of different green manure, ryegrass rotation has the highest number of bacteria, reaches 9.27×107CFU/g dry soil, and the tobacco mono-cropping is the least,4.54×107CFU/g dry soil. The number of culturable fungi in the tobacco mono-cropping is the most, reaches 6.07×10~4CFU/g dry soil, and the ryegrass rotation is the least,1.95×10~4CFU/g dry soil.