油菜菌核病拮抗细菌筛选及菌株BX-7的生防作用研究

从油菜根围土壤中分离出156株细菌,通过对峙实验的初步筛选,有10株细菌对油菜菌核病菌有一定的拮抗作用。菌株BX-7对油菜菌核病菌的菌丝生长有明显的抑制作用,对峙培养的油菜菌核病菌菌丝边缘由白色变为淡黄色,经过显微镜观察发现菌丝发生断裂、肿大或畸形等。菌株BX-7的挥发性产物和无菌发酵液均对油菜菌核病菌菌丝的生长有抑制作用。挥发性产物对菌丝生长的抑制率最高为74.09%。无菌发酵液随培养时间的不同其抑制效果有显著差异,在培养96 h时达到最佳。油菜叶片离体测定和盆栽试验结果表明,菌株BX-7的菌悬液和无菌发酵液均对油菜菌核病有较好的抑制作用,菌悬液处理的防效优于无菌发酵液。

Screening antagonistic bacteria against Sclerotinia sclerotiorum and the biocontrol effect of the strain BX-7

A total of 156 bacterial strains were isolated from the soil in the rhizosphere of oilseed rape plants. In a dual-culture test, ten strains exhibited the antifungal activity against S. sclerotiorum. After being subcultured for 10 times, the strain BX-7 still showed an obvious biocontrol effect. The strain BX-7 inhibited the growth of mycelia and induced alterations on mycelium morphology of S. sclerotiorum, such as hyphal yellowing, disconnecting or deformation. The volatiles from BX-7 could evidently inhibit hyphal growth of S. sclerotiorum, with the inhibitory rate up to 74.09%. The biocontrol efficacy of fermentation broth was different with different culture times, and the inhibition effect at 96 h was the best. Detached leaf test and pot experiments demonstrated that the bacterial suspension and the cell-free fermentation broth of BX-7 significantly controlled S. sclerotiorum, with the efficacy of the bacterial suspension being better than that of the cell-free fermentation broth.