Abstract: In this study,seven rhizobium strains (TG64,TG97,TG98,TG100,TG101,TG105 and TG115) isolated from nodules of Lespedeza daurica with good nodulation effect were selected. By measuring the growth phenotype and main nutritional components of L. davurica,combined with nodulation and photosynthetic characteristics,the physiological and biochemical mechanisms of growth promotion were preliminarily analyzed,and the growth promotion effects of different rhizobia were explored. Finally,the efficient rhizobium was identified by molecular biology,morphology and physiological and biochemical characteristics. The results showed that except for TG64,the other strains significantly increased the plant height,root length,biomass and protein content,and significantly improved the root construction of the plant. Among them,the promoting-growth effect of TG101 was the best. All strains were nodulated after inoculation,the number of nodules was 5-33 per plant,and the dry weight of nodules was 2.55-35.87 mg per plant. TG98,TG100,TG101 and TG115 significantly increased the chlorophyll content,photosynthetic capacity and nitrogen absorption capacity of the plants,which were the main physiological and biochemical mechanisms for promoting growth. TG101 with the best growth-promoting effect was identified as Bradyrhizobium erythrophlei. In conclusion,the rhizobia promoted the synthesis of chlorophyll,enhanced the activity of photosystem,and improved the photosynthetic capacity by improving the nitrogen nutrition of plants,thus promoting the accumulation of dry matter and regulating its growth. Among them,TG101 with the best growth-promoting effect was an efficient rhizobium,which provided strain resources and theoretical basis for the subsequent development of rhizobium agents suitable for L. davurica in the Loess Plateau,China.

Key words: Lespedeza daurica, Rhizobia, Screening, Identification

摘要： 本研究选择达乌里胡枝子(Lespedeza daurica)根瘤分离且结瘤效果较好的7株根瘤菌(TG64，TG97，TG98，TG100，TG101，TG105和TG115)，通过测定达乌里胡枝子生长表型和主要营养成分，结合结瘤和光合特性初步分析促生的生理生化机制，研究不同根瘤菌的促生作用；通过分子生物学、形态学和生理生化特性鉴定高效根瘤菌。结果表明：除TG64，其余菌株显著提高了株高、根长、生物量和蛋白质含量，改善了根系构建，TG101促生最明显。所有处理单株结瘤5~33个，根瘤干重2.55~35.87 mg；TG98，TG100，TG101和TG115显著提高了叶绿素含量、光合和氮吸收能力，是促生的主要生理生化机制。经鉴定，TG101为格木慢生根瘤菌(Bradyrhizobium erythrophlei)。综上，根瘤菌通过改善植株氮营养促进叶绿素合成、增强光系统活性，提高光合能力，进而促进干物质积累调控生长。其中TG101为高效根瘤菌，为后续研发适用黄土高原的达乌里胡枝子根瘤菌剂提供了菌种资源和理论依据。

关键词: 达乌里胡枝子, 根瘤菌, 筛选, 鉴定