Screening Plant Growth Promoting Rhizobacteria Resources And Their Characteristics Of Legumes

In present paper, Plant Growth Promoting Rhizobacteria(PGPR) from rhizosphere of 9 kinds legume(Medicago sativa, Trigonella ruthenica, Vicia sativa, Cicer arietinum, Coronilla varia,Caragana jubata, Glycyrrhiza uralensis, Vicia villosa, Astragalus membranaceus) in different areas of Gansu. Numbers of plant growth promoting rhizobacteria(PGPR) were determined by using the selective medium. The PGPR strains were determined based on the measurement of phosphate-solubilization capacity and IAA and GA secretion capacity by using the molybdenum blue spectrophotometry and HPLC, the nitrogen fixation capacity of nodules were determined by using acetylene reduction assay(ARA). In the end, some PGPR were identified based on its physiological characteristicsand 16 S rDNA sequence analysis. The main results were obtained as follows:(1) Used conventional bacteria separation methods, 167 inorganic phosphate solubilizing bacteria and 5 rhizobium had been isolated from rhizosphere of 9 kinds legume in different areas. The phosphorus dissolving ability was between 1.3μg·mL-1 and 574.4μg·mL-1. There were fifty strains whose dissolving ability were above 200.0 0μg·m L-1. The dissolving ability of strain PYRS6 reached 574.4μg·m L-1. There were obvious relationship between the phosphorus strains solubilization capacity and pH(P <0.01).(2) There were the difference in ability was large(IAA concentration was 2.09-43.3μg·mL-1, GA concentration was 1.02-30.34μg·mL-1). 27 strains of the 66 phosphate-solubilizing bacteria strains were able to secrete IAA, 18 strains were able to secrete GA. Strain PBRS5 had the stronge stability of secreting IAA, and 7 strains had ability of secreting IAA and GA.(3) 5 kinds nodules of the nitrogen fixation capacity had different activity(1.21-11.87umolC2h4 /g·h). The nitrogen fixation capacity as follow: Vicia villosa ﹥Trigonella ruthenica﹥Vicia sativa﹥Coronilla varia﹥Astragalus membranaceus.(4) The potential PGPR were identified based on 16 s rDNA, the results showed that strains belong to Pseudomonas fluorescens, Azotobacter chroococcum, Enterobacter cloacae, bacillus subtilis, Azomonas agilis, Bacillus megaterium, Azotobacter vinelandii and Klebsiella oxytoca. The rhizobium belong to Bradyrhizobium sp. and Rhizobium sp.。...