To Determine The Biodiversity of Free Living Nitrogen Fixing Phosphate Solubilizing Bacteria from Soil Samples of Pennisetumglaucum, Sorghumbicolour, Zeanmays

Abstract

Rhizosphere is the soil compartment influenced by the roots of growing plant. Bacteria present near the plant root are called rhizobacteria. The rhizosphere is rich in nutrients because of rhizodeposition (total carbon transferred from the plant root to the soil). Nitrogen and phosphorus are two major mineral compounds for plant growth. The rhizobacteria are responsible for fixing free nitrogen and making phosphate available for plants. Plants need nitrogen to make amino acid which makes proteins, which make the cells, which are important for growth. Lack of nitrogen gives yellow colour to plant. Phosphate is required for normal growth and maturity of plants and plays a significant role in photosynthesis, respiration, energy storage and transfer, cell division and cell enlargement. The plants are different from each other based on their metabolic pathways. On this basis the plants are divided into C3 and C4 (legumes and non-legumes). As phosphate and nitrogen are not easily available for plants, farmers are bound to use chemical fertilizers which lead to various side effects on the applicant, the crop as well as the field where the crop has been grown. Biofertilizer are a good approach to this problem as they consist of microorganisms which results in direct or indirect plant growth with no side effects. These isolated Plant Growth Promoting Bacteria can be used as potent biofertilizer. Root exudates of all the plants are different, which results in a diversity in rhizosphere. This bacterial diversity can be calculated by these parameters- richness, evenness, abundance and dominance. Rhizospheric and bulk soil samples of millet, sorghum and maize were collected from Jaspur village of Ahmedabad, Gujarat. Biochemical and molecular screening of the soil isolates was performed wherein their phosphate solubilizing ability and nitrogen fixing ability was checked along with other PGP activities. Further microbial diversity was calculated for all the soil samples using various biodiversity indices. On calculating various PGP activities, maize rhizospheric soil isolate MR 9 was found to be highest in production of Indole Acetic Acid (176.99 μg/ml) and siderophore (13.79%). Highest inorganic phosphate solubilization was observed by MiR 2 - 494.14μg/ml. On biodiversity study it was found that xii rhizospheric soil samples of all the plants were more diverse and even as compared to the bulk soil. On comparing all the data, it was observed that the soil sample of sorghum was more diverse and even than the soil samples of millet and maize. Further, the isolates selected for the pot studies were MiR7, SR3, SB3, MR 4 and MR 9. Isolates used for pot experiment can be further exploited and characterized for potent biofertilizer.