Isolation and Characterization of Drought-tolerant Rhizobacteria from Arid Regions of Central Kanpur, Uttar Pradesh, and its Growth-promotional Effects on Phaseolus vulgaris

Abstract

Abiotic elements including drought have a major impact on agricultural productivity worldwide. Bioinoculants consisting rhizobacteria have been proposed as an environment friendly beneficial method to strengthen crop resistance to drought stress. The current study involves isolation of rhizobacteria from arid and semi- arid regions of Kanpur Dehat, Uttar Pradesh and tested for drought tolerance at different concentrations of polyethylene glycol (PEG)-6000. Three bacterial isolates with maximum drought tolerance were characterized and identified molecularly, which include Pseudomonas sp. strain FD-37/23, Exiguobacterium aurantiacum strain GBRS02 and Microbacterium paraoxydans strain HZLJC2-1. Bacterial strains were screened for PGPR traits such as siderophore, indole-3-acetic acid (IAA), 1-aminocyclopropane-1-carboxylate (ACC) deaminase, ammonia production, hydrogen cyanide production, and phosphate solubilization. Exiguobacterium aurantiacum strain GBRS02 and Pseudomonas sp. strain FD-37/23, exhibited maximum drought tolerance of (0.81±0.09) and (0.82±0.08) while Microbacterium paraoxydans strain HZLJC2-1 shown drought tolerance of (0.69±0.03) at -0.73 Mpa water potential respectively, were selected for bio inoculation to bean plant. The bacterial inoculation resulted in significant increment in plant height, RWC, proline and other growth parameters. These findings may provide insight into the strains' potential application as rhizobacteria that stimulate plant development, either alone or in combination, which might aid local crops grow in drought-stressed environments.