Isolation, characterization, and influence of native rhizobacteria on growth of Brant's Oak (Quercus brantii Lindl.) seedlings

The bacteria species that have positive effects on plant growth and performance, which is called plant growth promoting rhizobacteria (PGPRs), can help or play a crucial role in reforestation programs. For this purpose, phosphate solubilizing bacteria were isolated from soil of Yasuj forests, Iran in this study. Ten isolates of phosphate solubilizing were extracted from five soil samples. Two out of ten bacteria strains with highest phosphate solubilizing activity were selected. The results of gram staining and other biochemical tests illustrated that those bacteria were identified as Microbacterium aurantiacum and Streptomyces cinereorectus. In order to study the effect of PGPR bacteria on growth performance of Brant’s oak seedlings, an experiment as completely randomized block design was done in greenhouse conditions. Treatments consist of four seedlings groups of non-inoculated (control), inoculated by M. aurantiacum, inoculated by S. cinereorectus and inoculated by a mixture of both strains. The results of analysis of variance of the effect of PGPR bacteria strains on growth performance of oak seedlings revealed that all studied traits with exception of stem length and shoot to root ratio were significantly affected by bacterial treatment. So that, inoculated plants showed better growth performance compared to the control treatment, but plants treated with both strains had lower stem and leaf fresh weights in comparison with pure inoculated plants. It can be concluded that the application of biofertilizers especially M. aurantiacum might be conducted to increase the growth and subsequent establishment of seedlings in the first year resulted in successful reforestation.