Identification of plant growth promoting rhizobacteria Elymus dahuricus and their effectives

【Objectives】 The ability of external growth promotion is an important indicator to measure the microbiological strain. To measure the selected plant growth promoting rhizobacteria and clarify their promoting growth efficiency to Elymus dahuricus can provide the basis for the application in production.【Methods】 The root morphology of Elymus dahuricus and rhizosphere soil were collected from Ali Region of Tibet in September 2014 Ten rhizobacteria strains, which could dissolve P, fix N and excrete 3-indole acetic acid (IAA) were isolated from root and rhizosphere soil with the conventional separation method of bacteria. The capacity of dissolving P and excreting IAA, the activity of fixing N in rhizosphere were investigated, and the effect of rhizobacteria inoculants on the growth of Elymus dahuricus were assessed.【Results】 Strains PWXZ10, 003PWXZ6, NXP17 showed the strongest phosphate solubilizing capacity (40.89 mg/L), nitrogenase activity 421.21 nmol/(mL·h), and IAA secreting ability (31.33 μg/mL), respectively. Compared with the control strains Pseudomonas sp. Jm92, inoculum 003PWXZ6 and NXP17 significantly increased plant height, aboveground biomass and underground biomass (P0.05), but the increase effects were not significantly different between the two strains (P0.05). In addition, inoculum 003PWXZ6 significantly increased root length, root surface area, root volume, root diameter, phosphorus content, containing nitrogen and crude protein content (P＜0.05). Compared with the control strains Pseudomonas sp. Jm92, above items were improved by 330%, 199%, 118%, 187%, 70%, 15%, and 19%, respectively, showing the strongest colonization ability in the rhizosphere.【Conclusions】 These results suggest that strains 003PWXZ6 and NXP17 has the best growth promoting effect to Elymus dahuricus among the strains. Therefore the strain resources is potential for the development of economy and environmental protection.