Isolation, screening and characterization of PGPR isolated from rhizospheric soils of Pigeonpea

Plant Growth Promoting Rhizobacteria (PGPR) is group of bacteria that colonize roots of plant and help in plant growth and disease suppression by various direct and indirect mechanisms. PGPRs are recognized as efficient soil microbes as bio-fertilizers for enhancing the growth of several crops and controlling soil borne pathogens. Hence, the present investigation was carried out to isolate, screen and characterize the PGPR from the rhizosphere soil of pigeonpea growing in different areas of Bijarkala and Kumarganj. A total of nine bacteria were isolated with the occurrence percentage of 1.92% to 98.1% from pigeonpea rhizosphere here and characterized for various plant growth promoting activities. In the present study, six isolates produced indole-3-acetic acid in the range of 56 to 97 mu g/ml and only single isolate (PN13) displayed phosphate solubilizing activity in Pikovskaya agar. In addition, six isolates were found to be positive for siderophore production and also showed antifungal activity against Fusarium udum. Catalase production was shown by almost all the isolates and production of HCN was detected in only single isolate i.e. PN11. Out of nine isolates, seven isolates were exhibited in vitro plant growth promotion activities and indicated that these isolates may be exploited as biofertilizers and microbial inoculants for pigeon pea crop as they enhanced plant growth via diverse mechanisms and offered an attractive strategy to replace synthetic fertilizers and pesticides.