Ecology, Environment and Conservation Paper

BIOCHEMICAL CHARACTERIZATION AND PGP TRAITS OF PLANT GROWTH PROMOTING RHIZOBACTERIA

P. Jayamma, R. Subhash Reddy, S. Triveni and A. Vijaya Gopal

Abstract

Plant growth promoting rhizobacteria (PGPR) are known to influence plant growth by various mechanisms. In search of efficient PGPR strains with multiple activities, a total of 57 bacterial isolates belonging to Bacillus, Pseudomonas, Azotobacter and Rhizobium were isolated from different rhizospheric soil of sorghum, maize, groundnut, chilli, tomato and castor of southern telangana zone. These isolates were biochemically characterized and screened in vitro for their plant growth promoting traits like phosphate solubilization, production of indoleacetic acid (IAA), hydrogen cyanide (HCN) and siderophore. All the isolates of Azotobacterand 90.5 % of Rhizobiumproduced IAA. But only 25% of Pseudomonasand 20% of Bacillus produced IAA. 45% of Pseudomonas, Rhizobiumand Azotobactersolubilized phosphate with highest solubilization zone of 17, 13 and 14 mm respectively. Whereas 35% of Bacillusisolates solubilized phosphate with highest solubilization zone of 19 mm. Production of HCN was commonly detected in the isolates of Rhizobium(67.5%) followed by Pseudomonas(65%), Bacillus(55%) and Azotobacter(25%). Production of siderophores was detected in the isolates of Rhizobium(43%) followed by Pseudomonas(25%), Bacillus(25%). None of the Azotobacterisolates were able to produce siderophore.