Efficacy of Silica Solubilizing Bacteria as Plant Growth Promoting Rhizobacteria and Their Biochemical Characteristics

Twenty eight isolates of silica solubilising bacterial inoculants were collected from rhizosphere soils of rice crop in Kurnool, Prakasam, Guntur and Anantapur districts of Andhra Pradesh by using insoluble source of silica. These isolates were verified for plant growth promoting rhizobacteria (PGPR) activity and then subjected biochemical tests in the Department of Agricultural microbiology, Advanced Post Graduate Centre, ANGRAU, Lam, Guntur, Andhra Pradesh, India. Two isolates, SiKPP-1 (Silica solubilizing isolate from Kurnool district, Pamulapadu Mandal and Pamulapadu Village - 1) & SiPYY-3 (Silica solubilizing isolate from Prakasam district, Yerragondapalem Mandal and Yerragondapalem Village - 3) showed the highest efficiency in the aspects of silica solubilization, phosphate solubilization, potassium release, exopolysaccharide production activity, indole acetic acid production activity, siderophore production activity and biochemical tests including starch hydrolysis, Hydrogen sulphide test, Indole production, Catalase test, Oxidase test, Gelatine liquification, Methyl red test, Vogues Proskauer test, Citrate Utilization and Ammonia production. Therefore these two isolates (SiKPP-1&SiPYY-3) were selected for further pot and field studies in direct sown paddy crop.