Biological Control Of Postharvest Diseases With Bacillus Sp. B1 On Muskmelons (Cucumis Melo L. Cv. Yindi)

The biocontrol capability of four different treatments of B1 (unwashed cell culture, culture filtrate, autoclaved culture and cell suspension) on major postharvest diseases of melons (cv. Yindi) was studied in this paper. Results showed that B1 unwashed cell culture significantly inhibited four major postharvest diseases of melons inoculated with Fusarium sp., Trichothecium roseum, Alternaria alternata and Rhizopus stolonifer, respectively. B1 culture filtrate significantly reduced lesion area of fruit inoculated with Fusarium sp. B1 autoclaved culture significantly decreased infection rate and lesion area of A. alternata. B1 autoclaved culture and cell suspension significantly reduced lesion area of Fusarium sp. and T. roseum.The higher density of B1, the better decay control of T. roseum on melons. The infection rate of T. roseum was significantly decreased on melons treated with B1 at 1×109 and1×107 CFU/ml respectively, however, B1 at 1×105CFU/ml had no effect on development of the pathogen; all of the three density of B1 inhibited the lesion area of T. roseum. B1 at 1×109 and 1×107 CFU/ml reduced the lesion development of Fusarium sp., but all three density had no inhibition on infection rate. Density of pathogen affected the severity of melon inoculated with T. roseum, too; the higher density of pathogen, the higher infection rate and the larger lesion area of disease. Decay control was related with inoculation time between B1 and T. roseum, although all treatments (melons was treated with B1 0h, 4h, 8h, 24h and 48h before inoculated with T. roseum) had significantly decreased disease development compared with control fruits, treatment before 48h had the best decay control efficacy. Combination with BTH or harpin enhanced the efficacy of B1 against T. roseum. Melons treated with B1 combinated with BTH or harpin had the lowest infection rate at 5 days after treatment. Melons treated with B1 combinated with AZX showed a better decay control than that of the treatment with B1. B1 population increased 24h after treatment on both B1 single treatment and B1 with A. alternata inoculation. The increasing was continued until 72h later. B1 significantly induced the POD activity of melon compared with the control; however, no effect was observed on β-1,3-glucanase (GLU).