Role of plant growth promoting bacteria in nutrient acquisition and plant stress tolerance response in saline soil

Abstract

High salt accumulation in soil is at increasing pace all over the world. It is caused by many natural as well as human activities, and causes degradation of soil structure in environment. Due to this, plant growth gets restricted in these areas because of nutrient deficiency. Many staple cereal crops are salt sensitive. This causes a reduction in their agricultural yield and people residing near these arid and semi-arid regions, cannot get sufficient supply. Many microorganisms are not adaptable to grow in high salt concentration, and thus not able to release metabolites which promotes plant growth. Use of chemical fertilisers worsen the condition and contaminates the ecosystem. Therefore, there is a need for biological way to resolve this problem. The objective of the study was to isolate salt tolerant bacteria from natural saline habitats and to screen their plant growth promoting activities under salt stress. In the present study, two bacterial species were isolated from a Sambhar Salt Lake, Rajasthan. They were able to grow up to 20% salt concentrations, and produce sufficient amounts of plant growth promoting metabolites like IAA, ammonia, Siderophore which ultimately promotes plant growth. Both the isolates have the capacity to solubilise phosphate, which was checked on Pikovskaya agar medium containing insoluble phosphate. Phosphorus is the most vital nutrient which plants require for their growth but less available to plants. These isolates were used as inoculums on sorghum seeds for nursery experiment. A significant increase in plant growth, root length, shoots length, fresh & dry biomass was observed in treated plants under salt stress as compared to the control plant. Enzyme activities of soil were also quantified at the end of the experiment. Therefore these isolates can be potentially used for plant growth promotion in saline soils.