Abstract:[Objective] We used different root and rhizosphere soils in Weinan, Xianyang, Ankang, Shangluo and Yulin, Shaanxi province of China to isolate plant growth promoting rhizobacteria (PGPR), and then studied the mechanism why they can promote the growth of plants. [Methods] Preliminary screening of PGPRs under the premises of PGPR may having the abilities of phosphate solubilization, N2-fixing, production of NH3 and indoleacetic acid (IAA) and antagonistic activity against three common pathogenic fungi. After that, multiple plant growth promoting activities were detected, maize growth enhancement by plant inoculation studies with these isolates alone individually and the mixture of each isolates under pot experiment conditions. [Results] In total of 158 strains were isolated. 17 of which have mechanisms and a striking plant growth promoting activity with respect to various plant parameters. Under pot culture conditions, compared with the control, the results showed that the strain which inoculated in combination was significant increase than inoculated alone, which in shoot length, root length, stem length, average diameter of stem and plant dry weight, respectively. [Conclusion] Isolates with multiple PGP activities can also be rhizospheric competent, providing promising isolates for PGPRs combination to resolve the challenges in field application of PGPR.
