Characterization of potential PGPR and antagonistic activities of Rhizobium isolates from different rhizosphere soils

PGPR function in three different ways synthesizing particular compounds for the plants facilitating the uptake of certain nutrients from the soil and lessening or preventing the plants from diseases. Some of Plant growth promoting characteristics such as phosphate solubilisation, Indole acetic acid (IAA) capacity, ability to produce ammonia (NH3) as sole nitrogen source, siderophore production and production of hydrogen cyanide were evaluated in fifteen Rhizobacteria isolated from different rhizosphere soils of Groundnut, Sunflower, Maize, Black gram, Green gram, Rice, Soy bean and Redgram. In this study, 47% Rhizobial isolates showed phosphate solubilization.73% of the isolates showed IAA production and 100% for ammonia, 53% for siderophores and 53% isolates showed for HCN production. All the fifteen isolates were examined for the potential to inhibit two fungal pathogens viz., Rhizoctonia solani and Sclerotium rolfsii under in vitro conditions. Out of fifteen isolates, only 3 isolates exhibited inhibition potential against two soil borne plant phytopathogen Among these isolates, RR-1 and GNR-1 were tolerant to all the heavy metals (100 I¼g ml-1).