Abstract: The aims are to clarify the stress tolerance characteristics，growth⁃promoting and disease control effects，and mechanisms of Pantoea agglomerans JHS0317 and Enterobacter ludwigii XL0404，which were plant growth⁃promoting rhizobacteria.The sensitivity of strains JHS0317 and XL0404 to temperature，pH value，and ultraviolet radiation was determined using the plate counting method.The growth⁃promoting effect on tobacco and the control effect on tobacco root rot caused by Fusarium were determined through indoor pot inoculation experiments.The results showed that the suitable growth temperature for strain JHS0317 was 28—35 ℃，and the suitable growth temperature for strain XL0404 was 28—45 ℃，with a lethal temperature of 65 ℃.Both strains could grow under pH conditions of 5—9，and the optimal pH was 5—7.They were sensitive to ultraviolet radiation.The results of pot experiments showed that the treatment of strains JHS0317 and XL0404 had a significant promoting effect on tobacco plant height，aboveground fresh weight，root fresh weight，total root surface area，and total root volume，which increased by 62.58%，44.76%，55.23%，63. 83%，71.43%，and 82.32%，49.84%，43.02%，43.38%，61.11% respectively compared to the control treated with water.The content of plant hormones such as brassinolide，gibberellin，and auxin，and the activity of resistance enzymes such as phenylalanine ammonia lyase，per oxidase，polyphenol oxidase and superoxide dismutase in tobacco leaves were also increased compared to the control.The treatment of strains JHS0317 and XL0404 could reduce the incidence rate and disease index of tobacco Fusarium root rot，and the control effects were 49.99% and 24.98%，respectively.In summary，the plant growth⁃promoting rhizobacteria strains JHS0317 and XL0404 have good stress resistance to high temperature and acid and alkali，and have significant growth⁃promoting and disease prevention effects on tobacco，with good application prospects.

Key words: Tobacco, Plant growth?promoting rhizobacteria, Stress tolerance, Growth promotion, Control effect

摘要： 为明确植物根际促生菌成团泛菌（Pantoea agglomerans）JHS0317和路德维希肠杆菌（Enterobacter ludwigii）XL0404 的耐逆特性及其促生防病效果和作用机制，利用稀释涂布平板计数法测定菌株JHS0317和XL0404对温度、酸碱度和紫外线的敏感性，通过室内盆栽接种试验明确其对烟草的促生作用及对烟草镰刀菌根腐病的防控效果。结果表明，菌株JHS0317 的适宜生长温度为28~35 ℃，菌株XL0404的适宜生长温度为28~45 ℃，致死温度均为65 ℃。两者在pH值为5~9的条件下均能生长，且最适pH值为5~7，但对紫外线较敏感。盆栽接种试验结果表明，菌株JHS0317和XL0404处理对烟草的株高、地上鲜质量、根系鲜质量、总根表面积和总根体积等指标均有显著促进作用，较对照（清水处理）分别提高了62.58%、44.76%、55.23%、63.83%、71.43%和82.32%、49.84%、43.02%、43.38%、61.11%，同时烟草叶片中油菜素内酯、赤霉素、生长素等植物激素含量及苯丙氨酸解氨酶、过氧化物酶、多酚氧化酶、超氧化物歧化酶等抗性酶活性较对照均有提升。菌株JHS0317和XL0404处理可降低烟草镰刀菌根腐病的发病率和病情指数，防效分别为49.99%、24.98%。综上，植物根际促生菌JHS0317和XL0404具有较好的耐高温和耐酸碱的特性，且对烟草具有显著的促生作用和防病效果，应用前景良好。

关键词: 烟草, 植物根际促生菌, 耐逆性, 促生作用, 防治效果