Abstract: Through outdoor pot experiments,alfalfa was selected as the object,and saline-alkali tolerant and rhizosphere growth-promoting bacteria JT4 and JG1,which were screened in the laboratory in the early stage,were selected as the test strains. Saline-alkali stress treatment was set in the experiment to explore the effects of these two rhizosphere growth-promoting bacteria on the growth and root physiological characteristics of alfalfa. It was found that under saline-alkali stress conditions,the plant height,root length,stem diameter,root fresh weight and root dry weight of alfalfa plants that inoculated with JT4 and JG1 were increased compared to that of CK. Simultaneously inoculation reduced the content of malondialdehyde,proline,catalase activity,and ascorbic acid peroxidase activity,while increased root activity,soluble protein content and soluble sugar content. The results indicated that the saline-alkali tolerant rhizosphere growth-promoting bacteria JT4 and JG1 could effectively alleviate the damage of saline-alkali stress on alfalfa roots,and provided a theoretical basis for the application of aline-alkali tolerant rhizosphere growth-promoting bacteria JT4 and JG1 in the screening of plant saline-alkali resistant materials and the improvement of saline-alkali soil.

Key words: Rhizosphere growth-promoting bacteria, Alfalfa, Saline-alkali stress, Physiological characteristics of root system

摘要： 通过室外盆栽试验，以紫花苜蓿为对象，并选择实验室前期筛选得到的耐盐碱且具有促生能力的根际促生细菌嗜麦芽寡养单胞菌(JT4)和普城沙雷氏菌(JG1)作为供试菌株，试验设置了盐碱胁迫处理以探究两种根际促生细菌对紫花苜蓿生长和根系生理特性的影响，发现在盐碱胁迫条件下，与CK相比，紫花苜蓿接种JT4和JG1后，增加了株高、根长、茎粗、根鲜重和根干重等；同时接种降低了丙二醛含量、脯氨酸含量、过氧化氢酶活性和抗坏血酸过氧化物酶活性，提高了根系活力、可溶性蛋白含量和可溶性糖含量。表明耐盐碱根际促生细菌JT4和JG1能有效缓解盐碱胁迫对紫花苜蓿根系的损伤，为耐盐碱根际促生细菌JT4和JG1在植物抗盐碱材料的筛选和盐碱地改良中的应用提供了理论依据。

关键词: 根际促生细菌, 紫花苜蓿, 盐碱胁迫, 根系生理特性