Fungal diversity in tobacco rhizosphere soil

Tobacco soil-borne diseases occur widely and usually cause serious losses in tobacco production. 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 in 12 areas of Heilongjiang, Shandong, Guangxi and Yunnan provinces was conducted during 2010 and 2011 summer. By means of soil dilution plate method, totally 1,278 fungal isolates were obtained from 224 soil samples. From which 86 fungal species belonging to 25 genera were identified morphologically, including 6 species belonging to 4 genera of Zygomycota, one species belonging to one genus of Ascomycota, and 79 species belonging to 20 genera of anamorphic fungi. The fungal population analysis indicates that Penicillium, Trichoderma, Fusarium and Aspergillus were the dominant fungal groups in tobacco-growing soil, accounting for 16.74%, 14.32%, 13.54% and 11.50% of the total isolates respectively. The fungal diversities in tobacco rhizosphere soil were significantly different in the 12 soil-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 the 12 soil-sampling regions were also different in similarity. The similarity coefficient of fungal populations was higher (Cj=0.9375) in Yongsheng and Dali of Yunnan Province, but lower in Yishui of Shandong Province and Yuxi of Yunnan Province (Cj=0.4231).