Abstract: 【Objective】To explore the inhibitory effect of biocontrol strain JT86 on sclerotia-producing pathogens of tobacco. 【Methods】The cell wall hydrolase activities in the fermentation broth of Pseudomonas aeruginosa JT86 were detected using the double-antibody sandwich method. The mycelium and sclerotia morphological changes of the pathogen treated with JT86 fermentation broth were observed using scanning electron microscopy. The inhibitory effects on the hyphal growth and sclerotia germination of Rhizoctonia solani,Sclerotium rolfsii,and Sclerotinia sclerotiorum were tested.【Results】The inhibitory rates of JT86 fermentation broth on the hyphal growth of R. solani,S. rolfsii and S. sclerotiorum were 77.07%,50.82%,and 95.25%,respectively. After 24 h treatment with JT86 fermentation broth,the sclerotia of the three pathogens did not germinate,with inhibitory rates all reached 100%. JT86 fermentation broth had high protease,cellulase and chitinase activities,but did not produce indoleacetic acid. Scanning electron microscopy showed that JT86 fermentation broth could cause severe hyphal atrophy and deformity of R. solani.【Conclusion】The JT86 fermentation broth had good inhibitory effects on the growth and development,as well as sclerotial germination of R. solani,S. rolfsii and S. sclerotiorum.

Key words: Tobacco soil borne pathogens, Sclerotium, Biocontrol strain, Pseudomonas aeruginosa