Abstract:

As the potential biocontrol bacteria, Bacillus velezensis was studied for its biological control of peanut stem rot caused by Sclerotium rolfsii with coculture method, research of antagonistic mechanism and pot experiments. By coculture method on PDA, B.velezensis can inhibit the hyphal growth of S. rolfsii significantly, with an inhibition rate of 81. 93%, destroy the structure of the pathogenic mycelium and prevent the formation of sclerotia. In order to understand antagonistic mechanism of B. velezensis, it was found that B. velezensis can produce protease, cellulase, amylase and siderophore, which aseptic fermentation filtrate also has an antagonistic effect. Under pot experiments the treatments with bacteria liquid can inhibit the occurrence of peanut stem rot caused by S. rolfsii, reduce the peanut disease index, and have a certain promotion effect on the growth of peanuts. Peanuts which colonizated with S. rolfsii for 2 days and then sprayed by the bacteria liquid exhibited greater than other treatments with 66. 15% biocontrol efficacy against S.rolfsii. B. velezensis can be used for the prevention and treatment of peanut stem rot caused by S. rolfsii, and has a good prospect for biocontrol.

Key words: Bacillus velezensis, Sclerotium rolfsii, antagonistic, growth promoting, biological control