烟草黑胫病不同植物源生防菌的筛选及防效测定

植物内生菌是生防菌剂的宝贵资源，在作物病害生物防治中具有重要作用。本文采用稀释平板法从8种不同植物茎组织中分离内生菌，采用二次平板对峙法筛选拮抗菌，通过形态观察、生理生化反应及16S rDNA分析鉴定菌种，利用盆栽和田间试验检验其生防防效，并测定其促生作用。结果表明:分离出内生菌共89株，其中烟草疫霉菌拮抗效果较好的菌株6株，分别为J11、J21（构树），T3、T23（马铃薯），G3（枸杞）和KY（烟草）。KY被鉴定为亚麻假单胞菌（Pseudomonas lini），J11、G3和T3为蜡状芽孢杆菌（Bacillus cereus），T23为短小芽孢杆菌（Bacillus pumilus），J21为枯草芽孢杆菌（Bacillus subtilis）。KY、T23及J11的相对防效较好，盆栽相对防效分别为75.41%、63.93%、70.49%，大田相对防效分别为63.62%、51.11%、52.67%，且对烟株的株高、茎围均有促生作用。 

Screening and control efficacy of different plant-derived biocontrol bacteria against tobacco black shank disease

Plant endophytes are valuable resources of biocontrol agents and play an important role in the biological control of crop diseases. In this paper, endophytic bacteria were isolated from 8 different plant stem tissues using the dilution plate method. Antagonistic bacteria were screened using the secondary plate pairing method. The bacterial species were identified through morphological observation, physiological and biochemical reactions, and 16S rDNA analysis. The potted plants and field tests were used to test the bacteria biocontrol and prevention effect, and measure its promoting effect. The results showed that a total of 89 strains of endophytic bacteria were isolated. Among them, 6 strains with better antagonistic effect on Phytophthora nicotianae were J11, J21 (paper mulberry), T3, T23 (potato), G3 (medlar) and KY (tobacco). KY was identified as Pseudomonas lini, J11, G3, and T3 were Bacillus cereus, T23 was Bacillus pumilus, and J21 was Bacillus subtilis. KY, T23 and J11 had better control effect against tobacco black shank disease, with the control efficiency of 75.41%, 63.93% and 70.49 in pot trials and 63.62%, 51.11% and 52.67% in field trials, respectively, and it can promote the growth of tobacco plant height and stem circumference.