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为探讨烟草根际生防细菌对烟草疫霉Phytophthora nicotianae的抑菌机制,从重庆地区连作烟田健康烟株根际土壤分离获得5株荧光假单胞菌Pseudomonas fluorescens拮抗菌株。通过平板对峙及代谢产物抑菌试验筛选对烟草疫霉具有高效拮抗作用的菌株,其中,P-72-10菌株抑菌效果最强,抑菌带半径达13.0 mm,相对抑制率为68.57%,且该菌株代谢产物对烟草疫霉菌丝生长有明显的抑制作用,相对抑制率达25.39%～46.03%;显微观察发现该菌株可引起烟草疫霉菌丝的分支增多,菌丝顶端膨大呈畸形,多数菌丝中间或顶端细胞的细胞壁加厚、原生质浓缩和产生类似厚壁孢子的细胞。在温室盆栽条件下P-72-10菌株对烟草黑胫病也表现出良好的控病效果,对抗病和感病品种的相对防效分别为53.57%和66.37%。
In order to explore the bacteriostasis mechanism of biocontrol bacterium in tobacco rhizosphere on Phytophthora nicotianae, five strains of Pseudomonas fluorescens antagonistic strains were isolated from rhizospheric soil of healthy tobacco plants in Lianzuo tobacco field in Chongqing. P-72-10 strain had the strongest bacteriostasis effect, the radius of bacteriostatic zone was 13.0 mm, the relative inhibition rate was 68.57% And the metabolites of the strain had a significant inhibitory effect on the growth of Phytophthora nicotianae. The relative inhibition rate was 25.39% ~ 46.03%. Microscopic observation showed that the strain could cause the increase of the branch of Phytophthora nicotiana, The majority of hyphal cells in the middle or top of the cell wall thickening, protoplast concentration and produce thick walled spore cells. The P-72-10 strain also showed good control effect on tobacco black shank in pots under greenhouse conditions, and the relative control effects on resistant and susceptible varieties were 53.57% and 66.37%, respectively.