Isolation and initial characterization of diazotrophic plant growth promoting rhizobacteria (PGPR) from rice rhizosphere of Parsa and Bara district of Nepal

Abstract

Diazotrophic bacteria were isolated from the rhizosphere of rice plants in two districts (Parsa and Bara) of Nepal. The rate of nitrogenase enzyme activity based on acetylene reduction assay showed remarkable variation in these isolates which ranged from 0.69 to 1.63 mmol C₂H₄ formed/mg protein/h. Their plant growth promoting characters were also analysed. It was observed that 64.3% of them showed IAA production, 32.1% phosphate solubilization, 53.6% siderophore production whereas 10.7% isolates showed all the plant growth promoting characters. Based on biochemical characterization and carbon source utilization they were clustered in 6 clusters. It is hereby reported that species of Pseudomonas, Klebsiella, Azotobacter and Agrobacterium were predominantly present in this region especially in the rhizosphere of rice plants.