Rhizosphere: An Ideal Site for PGPR Screening

Abstract

Rhizosphere is the thin layer of soil surrounding plant roots and play important role in plant-bacterial interactions. This rhizospheric region around plant roots is an area rich in plant growth promoting bacteria. These plant-associated bacteria usually promote plant growth through various direct or indirect mechanisms including phosphorous solubilization, phytohormone production, nitrogen fixation, iron sequestration via siderophores and production of extracellular polymeric substances etc. PGPR modify root system of plants by the production of various phytohormones which facilitate the uptake of nutrients from soil more efficiently resulting in enhanced plant growth. Objective: To study the growth conditions of bacterial isolates. Methods: In the current study, rhizobacterial isolates have been isolated from indigenous environment and characterized macroscopically, microscopically, and biochemically. These isolates have been biochemically identified using Bergey’s Manual of systematic bacteriology and using ABIS 7 online software and evaluated for their various growth promoting attributes. Results: AS2 was identified as Bacillus sp., while AS3 and AS4 were identified as Pseudomonas sp. All three strains exhibited auxin production, nitrogen fixation, and HCN production capabilities. However, AS4 lacked ammonification and zinc solubilization potential, and AS3 lacked ACC deaminase activity. Conclusions: It is concluded that these bacterial isolates have ability to promote plant growth. These bacterial isolates can be further used for plant stimulating agents for sustainable agriculture practices.