防治烟草赤星病拮抗根际芽孢杆菌的筛选

 从健康烟草根分离到669株根际芽孢杆菌,通过平板对峙培养、代谢产物活性检测,筛选到9株抑制烟草赤星病菌(Alternaria alternata)活性较强的菌株,其菌体及粗代谢产物产生的抑菌圈直径均在10 mm以上;离体防效和田间小区防治试验表明,菌株B6、B75的含菌发酵液和粗代谢产物的离体防效分别为75.6%、76.9%和62.5%、64.7%,小区防效分别为70.3%、75.8%和60.3%、64.4%。粗代谢产物的抑菌作用试验发现,菌株B75的粗代谢产物在一定浓度范围内均能抑制赤星病菌孢子萌发、菌丝生长与产孢。

Screening of antagonistic rhizospheric spore-producing bacilli against tobacco brown spot

669 rhizospheric spore-producing bacilli were obtained from healthy tobacco roots.By dual culture on PDA plates and determining inhibition activity of antibiotic substances,it was found that 9 potential biocontrol isolates showed good antagonistic effects to Alternaria alternata,the pathogen of tobacco brown spot,and the diameter of inhibition zone of bacteria and crude antibiotic substances was up to 10 mm.Inoculation of detached leaves of tobacco variety K326 with bacterial suspension and crude antibiotic substances of B6 and B75 resulted in control effect reaching 75.6%,76.9% and 62.5%,64.7%,respectively.Results in field experiment showed that preparation of B6 and B75 reduced the incidence of tobacco brown spot to 70.3%,75.8% and 60.3%,64.4%,respectively.Crude antibiotic substances of B75 could inhibit mycelium growth,sporulation and spore germination of tobacco brown spot pathogen.