烟草青枯病颉颃细菌的筛选及其防病效果研究

从安徽、浙江等地的烟草、蕃茄和辣椒等茄科作物根标、根围土壤和病、健植株组织中，分离纯化到１６８个细菌菌株，通过室内异步培养法和平板扩散法，筛选出１７个对烟草青枯病菌具有一定颉颃作用的菌株，其中，ＡＱＢ—４６和ＡＱＢ一３３两菌株抑菌能力最强，抑菌圈直径分别为３３．７ｍｍ和３０．６ｍｍ。盆栽防病结果表明，这２个菌株对青枯病的防治效果在接种青枯菌后的３０ｄ内一直维持在５４．２％６４．７％。菌株ＡＱＢ－６２室内抑菌试验效果明显低于ＡＱＢ－４６和ＡＱＢ一３３，但盆栽防病的效果在接种后的２０ｄ内也一直维持在４９．９％５３．０％的水平。接种前３ｄ喷施颉颃菌的各处理，其防病效果远高于接种后３ｄ喷施颉颃菌的各处理，前者防效最高为６４．７％，而后者最高仅为１５．０％，说明颉颃菌对烟草青枯病的防治主要表现为预防。此外，颉颃菌的防病作用主要表现为减轻发病程度，而对发病率没有影响。颉颃菌除具有直接的抑制青枯菌定殖、繁衍、扩展外，有的菌株如ＡＱＢ—６２还具有一定的诱导抗性作用。ＡＱＢ－４６，ＡＱＢ－３３和ＡＱＢ－６２等３个菌株可望研制成生物农药，使之更有效地防治烟草青枯病。

The screening of antagonistic bacteria against tobacco bacterial wilt and their control effects

168 bacteria isolates were obtained from rhizosphere, root medium soils and both diseased and healthy plants ofsolanaceous crops including tobacco, tomato and hot pepper in Hefei, Xuancheng and Shaoxin. 17 strains out of 168bacteria exhibted clear inhibiting activity to pathogen Rastonia solanacearum by the differred antagonism procedureand the plate diffusion methods, of which strains AQB - 46 and AQB - 33 had the strongest inhibiting effect, withinhibiting ring diameter of 33. 7mm and 30. 6mm respectively. Their control effects have maintained high levels from54. 2 % to 64. 7 % throughout 30 days after inoculated with pathogen. Though AQB - 62 had a lower inhibitory ability than AQB - 46 and AQB - 33, it showed higher control effect to tobacco bacterial wilt during 20 days after inoculation, its control effects ranging from 49. 9% to 53. 0%. According to control effect to tobacco bacterial wilt, alltreatments with antagonistic bacteria before inoculaion displayed much higher levels than those after inoculaion, theformer being 64. 7 % and the latter being 15. 0 %. However, control effects of antagonistic bacteria to tobacco bacterial wilt mainly embodied lightening the disease seventy not reducing the disease incidence. Antagonistic bacteria gotcontrol over disease by restraining pathogen settlement, breeding and spreading, but some strains took effect by increasing disease resistance of plant, such as AQB - 62. To summarize, antagonistic bacteria could create obvious prevention to tobacco bacterial wilt. Strain AQB - 46, AQB - 33 and AQB - 62 could be developed into biological pesticide, in order to control tobacco bacterial wilt with better effect.