防治烟草黑胫病的根际细菌分离与筛选

从云南昆明、玉溪、曲靖、楚雄、大理等地13份烟田根际土样中,经分离纯化得到753株根际细菌.通过对黑胫病病原(Phytophthora parasitica.var.nicotiana)的平板拮抗筛选,共得到有抑制病原菌生长的根际细菌97株,用细菌悬液浸泡烟草种子,通过测定烟草种子发芽率和对烟草苗期的促生作用,选出有较好促生作用的细菌19株,再进行温室盆栽测定,选出对烟草黑胫病有防病促生作用的根际细菌6株,分别编号为RB-1、R4、RB-42、RB-59、RB-78、RB-89.在研究过程中发现,从明胶、几丁质培养基和从根表上分离到的细菌,其防病促生作用的机率较高.在防治苗期黑胫病的温室试验中,RB-42和RB-89菌株的相对防治效果分别达到42.22%和37.78%.通过形态学与生理生化初步的鉴定,RB-42、RB-78、RB-89鉴定为假单胞杆菌(Pseudomonas spp.),R4鉴定为芽孢杆菌(Bacillus sp.).

Isolation of tobacco rhizobacteria and their antagonism to Phytophthora parasitica. Var.nicotiana

Rhizosphere bacteria were isolated from different positions of roots of growing tobacco plants using different mediums 97 bacterial isolates were first screened from 753 isolates obtained from 13 tobacco rhizosphere soil samples from Kunming, Yuxi,Dali,Chuxiong and Qujing with antagonism to \%Phytophthora parasitica \%var \%nicotiana \% 19 isolates caused better germination and promoting at seed plot were second screened, 6 isolates caused leaf and height significant promoting in repeated greenhouse were last screened In the screen process, it was shown that the high screened efficient of bacteria was isolated from root surface using of chitin and glutin medium The protection effect of RB\|42 and RB\|89 reach up to 42 22% and 37 78% when compared with water Isolates from tobacco rhizosphere were mostly Gram\|negative bacteria On the basis of identification of the culture and physiology characters, RB\|42,RB\|78,RB\|89 were identified as \% Pseudomonas\% spp, R4 was identified as \% Bacillus\% sp