Screening and Isolation of Plant Growth-Promoting Bacteria from Forest and Coastal Regions of Saurashtra, Gujarat

Abstract

Chemical fertilisers have been used intensively in recent years leading to the degradation in the quality of the soil. Diversity of microorganisms is important, as their unique features can be utilized for crop production and environment. Microorganisms are usually inhabited in all parts of the plant from the roots to the shoot and internal regions of the plants. Rhizosphere microbial variety conveys an assortment of microorganisms which offer advantageous properties to the plant environments. In the present study, an attempt has been made for the screening of bacteria for plant growth- promoting activities such as nitrogen fixation, phosphate solubilization and indole acetic acid production. Soil samples were collected from thirty-four different places of districts Junagadh, Gir Somnath, Amreli, Diu, Dwarka and Jamnagar. Twenty soil samples were from forest region and fourteen soil samples were from the coastal region of Saurashtra. The nitrogen-fixing capability of the isolates was evaluated using Ashby's media containing bromothymol blue. Total 57 nitrogen-fixing bacteria based on their colony morphology were isolated, of which 49 bacterial isolates were able to solubilize phosphate and 27 were able to produce indole acetic acid. Of 57 bacterial isolates, 23 isolates showed positive results for nitrogen fixation, phosphate solubilization and indole acetic acid production. Nitrogen and phosphorus are one of the major essential macronutrients for plant growth and development. Indole acetic acid serves as one on the plant hormone for growth of plants. The present study indicates 23 bacterial isolates can have the potential for plant growth-promoting bacteria and as a greater number of isolates were from forest region which also indicates the fertility of the soil.