Fungal Diversity In Tobacco Rhizosphere Soil

Tobacco is one of the important economic crops and it is widely cultivated in China. The growing area and yield of tobacco in China have topped No.1in the world. During tobacco growing period a number of soil-borne diseases could happen and cause serious damage to tobacco growth. Among the various factors affecting tobacco soil-borne diseases, the rhizosphere microbes and distribution pattern play an important role in balancing plant growth and inhibiting tobacco soil-borne diseases. The work of effective control of soil-borne diseases has been an important issue in tobacco production. As an important component of microorganisms in rhizospheric soil, many fungi are closely associated with soil-borne diseases and antagonism or parasitism of pathogenic fungi. Investigation of fungal diversity in tobacco rhizospheric soil will contribute to explain the rhizosphere soil microbial ecology and effective control of tobacco soil-borne disease.In order to understand the relationship between tobacco rhizosphere soil fungi and soil-borne diseases, the investigation of rhizosphere soil fungal diversity in tobacco fields in12areas of Heilongjiang, Shandong, Guangxi and Yunnan provinces was conducted during2010and2011summer. By means of soil dilution plate method, totally1278fungal isolates were obtained from224soil samples. From which86fungal species belonging to25genera were identified morphologically, including five species belonging to four genera of Zygomycota, one species belonging to one genus of Ascomycota, and80species belonging to20genera of anamorphic fungi. The fungal population analysis indicates that Penicillium, Trichoderma, Aspergillus and Fusarium were the dominant fungal groups in tobacco-growing soil, accounting for16.74%,14.32%,11.50%and13.54%of the total isolates respectively. The fungal diversities in tobacco rhizosphere soil were significantly different in the12soil-sampling regions. Zhucheng of Shandong province was the highest in Shannon diversity index (H’=2.0666) and Pielou evenness index (J=0.6898). Yuxi of Yunnan province was the highest in Margalef richness index (R=4.0687). The fungal diversities in the12soil-sampling regions were also different in similarity. The similarity coefficient of fungal populations was higher (Cj=1.0000) in Qingdao and Pingdu of Shandong province, but lower in Yishui of Shandong province and Yuxi of Yunnan province (Cj=0.4231).