Phosphate solubilizing rhizobacteria as alternative of chemical fertilizer for growth and yield of (Var. Galaxy 2013).

Aim: The presence of Phosphorus as a macronutrient in soil is necessary for plant growth and its deficiency restricts crop yield. Therefore, the aim of current study is to isolate promising rhizospheric phosphate solubilizing bacteria presenting with plant growth promoting (PGP) traits and their utilization as biofertilizers to improve growth and nutrition.

Method: Out of 30 isolates obtained from rhizosphere of various plants of different regions, 10 best PSRB strains (WumS-3, WumS-4, WumS-5, WumS-11, WumS-12, WumS-21, WumS-24, WumS-25, WumS-26 and WumS-28) were selected based on their high P solubilization and good PGP (auxin, psiderphore, HCN, Nitrogen fixation) activities. (Var. Galaxy 2013) was used as an experimental crop under laboratory and field conditions.

Results: In this study, P solubilization capacity of selected strains were found 4-7 solubilization index on agar plate and 30-246 µg/ml in liquid broth respectively. The optimum conditions for phosphate solubilization under condition were found 35 °C at pH 7, glucose as good carbon source and ammonium nitrate as a good nitrogen source. Furthermore, the selected strains had the ability to produces phytohormones (indole acetic acid), siderophore, ammonia and Hydrogen Cyanide. Finally, PSRB inoculum showed significant (p < 0.05) increase (50%-80%) in seed germination while 10-90% increase in root length and shoot length was found as compared to control in laboratory condition. Under natural conditions, 40-80% increase in seed germination while 5-34.8% increase in shoot length and 5-96% increase in seed weight was also observed.

Conclusion: Isolated strains are promising PSRB that enhance plant growth and this research is a base for recommending the use of these bacterial strains for biofertilizer, as an alternative of chemical fertilizer, for L. production.