Comparative Response of Phosphate Solubilizing Indigenous Bacillus licheniformis, Pantoea dispersa and Staphylococcus sp. From Rice Rhizosphere for Their Multifarious Growth Promoting Characteristics

Phosphorus (P), a major limiting macronutrient for plant growth and development can be made available to the plants by applying phosphate solubilizing bacteria (PSB) as bioinoculants in different cropping systems as they solubilize the inaccessible P in soil and make it available to plants in a sustainable and environment-friendly manner. The objectives of the present study were to isolate and characterize PSB from the rice rhizosphere and study their plant growth-promoting attributes in rice. Three promising isolates Bacillus licheniformis, Pantoea dispersa, and Staphylococcus sp. were selected based on qualitative and quantitative P solubilizing assay. Invitro studies were performed for their plant growth-promoting traits. Liquid Chromatography Mass Spectrometry (LCMS) analysis of the culture supernatant of the test isolates was performed to study the organic acid production for P solubilization. The bacterial strains showed positive results for indole acetic acid (IAA), 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase enzyme, and siderophore production. LCMS analysis revealed the presence of glutaric acid, propionic acid, dicarboxylic acid, and hexanoic acid which might have helped in P solubilization. Application of individual PSB and their consortium in seeds enhanced percent seed germination and seedling vigor index in rice over control. The highest percent seed germination and seedling vigor index were observed in consortium treatment. Significant enhancement in root traits like root length, root volume, root dry weight, root projected area, root tips number, root segments, root volume, and average root diameter was observed in the rice plants treated with PSB as compared to control. Our results suggest that Bacillus licheniformis, Pantoea dispersa, and Staphylococcus sp. are potent plant growth-promoting bacteria and could be implemented as a low-cost bio-inoculant in the rice agriculture system.