Characterization and utilization of multi-trait plant growth promoting rhizobacteria from arid soils of western Rajasthan for enhancing drought resilience in an arid legume

In the study, plant growth promoting rhizobacteria (PGPR) indigenous to arid western Rajasthan were isolated and screened for plant growth promoting (PGP) capabilities. Ten isolates showing multiple PGP activities were identified as Pseudomonas sp. G6-3, Staphylococcus sp. G6-4, Bacillus badius G8-6, Agrobacterium sp. G8-7, Bacillus pseudomycoides G10-1, Staphylococcus capitis subsp. capitis G11-4, Bacillus paralicheniformis G11-5, Bacillus subtilis G12-3, Stenotrophomonas pavanii G12-4, and Solibacillus isronensis G21-9. Physiological profiling of these isolates demonstrated them to be tolerant to drought (25% PEG-6000), high temperature (40 degrees C), alkalinity (pH 10.0), and salinity (4.5% NaCl). These PGPR significantly improved clusterbean seedling characteristics in moisture stress-induced hydroponic flask cultures and pots. PGPR inoculation of clusterbean in drought-induced pots significantly enhanced the plant dry weight by 15-33%, plant water potential by 5-8%, and the relative water content of leaves by 4-16%. There was also a significant reduction in the levels of anti-oxidant enzymes and proline in plant tissues under drought conditions, which indicated lower levels of stress experienced by the treated plants. These were translated into yield enhancements by 13-15% under rainfed conditions. The study demonstrates the ability of stress tolerant PGPR from arid western Rajasthan in enhancing drought resilience of arid legumes besides promoting their growth, and their potential utility in sustainable arid agriculture systems.