Abstract: In order to screen the resources of Indigofera amblyantha with a wide range of host recognition and strong nodule formation and nitrogen fixation ability,the root nodule samples were collected from five different ecological functional areas in 22 counties (cities) of Guizhou Province,the morphological structure of the bacteria was observed after isolation and purification of rhizobia strains. Combined with the results of 16S rRNA gene sequence analysis,different species of Indigofera amblyantha rhizobia from different regions were selected. The potted grafting method was adopted combined with the determination of the nitrogenase activity of the strain to screen the excellent rhizobia strains with strong nodule formation and nitrogen fixation ability and good plant growth promotion effect. The results showed that 33 rhizobia strains were isolated and purified,and were identified to 22 species belonging to 6 genera. Six excellent growth-promoting and nitrogen-fixing rhizobial strains were screened out,among which strain LMIR32-1 was the best growth-promoting rhizobial strain,with the nitrogenase activity as high as 263.05 IU·L^-1,and its nitrogenase activity and growth-promoting effect were significantly different (P<0.05) or highly significantly different (P<0.01) with the other 5 strains. The results of this study can provide valuable germplasm resources for the comprehensive application of leguminous forage symbiotic system in local agricultural and animal husbandry production and ecological environment construction.

Key words: Indigofera amblyantha, Rhizobium, Floristic analysis, Strains screening, Karst Mountain Region of Guizhou

摘要： 为了筛选获得寄主识别范围广、结瘤固氮能力强的抗逆高效多花木蓝（Indigofera amblyantha）根瘤菌资源，本研究从贵州省22个县（市）5个不同生态功能区采集多花木蓝根瘤样品，经分离、纯化根瘤菌株，观察菌体形态结构，结合16S rRNA基因序列分析比对结果后，选择来自不同地域、不同种类的多花木蓝根瘤菌，采用盆栽回接方法，结合菌株固氮酶活性的测定，筛选结瘤固氮能力强、植物促生效果好的优良根瘤菌株。结果发现：共分离纯化获得33个根瘤菌株，经鉴定分属6属22种。筛选出优良促生固氮根瘤菌6株，其中分离自罗甸县沫阳镇多花木蓝根瘤样品的菌株LMIR32-1为最优促生根瘤菌，其固氮酶活性高达263.05 IU·L^-1，酶活力及植物促生效果与另外5个优良菌株的差异均达显著（P<0.05）或极显著（P<0.01）水平。本研究结果为豆科牧草共生体系在本地区农牧业生产及生态环境建设中的综合应用提供了理论基础。

关键词: 多花木蓝, 根瘤菌, 区系分析, 菌株筛选, 贵州岩溶山区