Abstract:

This study aims to use antagonistic bacteria to control plant diseases, and provide more feasible biological control methods for the diseases control of peach. A strain Pseudomonas fluorescens RN-88 obtained previously in the authors lab was used to determine the inhibitory activity of the fermentation broth against Monilinia fructicol, which was determined by the cup and saucer method. The stability of the broth under different environments such as pH, temperature, and ultraviolet (UV) light was evaluated by the inhibition circle method. The results showed that the antagonistic bacterium RN-88 reduced the incidence of brown rot in peaches, and its fermentation broth inhibited M. fructicol up to 44.69%, and the loss of fungal inhibitory ability of the fermentation broth was effectively reduced by filtration compared to autoclaving. The inhibition activity of the fermentation broth was stable in alkaline solutions at pH 7.5 - 9.0, and was reduced in acidic solutions (3.0 ≤ pH ≤ 6.5). There was no effect on the inhibition rate of the fermentation broth by temperature and ultraviolet (UV) light. All above, fermentation broth of Pseudomonas fluorescens RN-88 has good environmental stability which has the potential to be developed to a novel fungicide. This study also provides a theoretical basis for the application of Pseudomonas fluorescens.

Key words: Monilinia fructicola, biocontrol bacteria resources, inhibition activity, environmental tolerance, Pseudomonas fluorescens