Title: Studies of halotolerant PGPR inoculants for sustainable agriculture
Abstract:
Salinity of soil is an emerging problem of agriculture that reduces plant growth. Salt affected soils are widely distributed throughout the world. Salinity is a presence of salt content in soil. Addition of salts, metals and xenobiotic chemicals to the soil severely reduce biogeocycling thus reducing the fertility of soils. In such stress conditions Plant growth promoting rhizobacterial inoculants may improves saline soil fertility and induces plant growth promotion. There are five major classes of plant growth promoting substances i.e. Auxin, Gibberellic acid, Cytokinins, Ethylene and abscisic acid. Plant growth promoters may play an important role in the plant growth promotion in such conditions. The present study is an attempt to evaluate the effect of halotolerant PGPR on growth of Sugar cane and saline soil properties by pot assay method. Halotolerant PGPR cultures were isolated from saline soil from Baramati region. The selected isolates were characterized on the basis of morphological and biochemical tests. The isolates identification was done based on Bergey’s Manual of Determinative Bacteriology. Identified cultures are Azotobacter spp, Rhizobium spp , Azospirillum spp. These cultures are salt tolerant upto 2 % NaCl and having nitrogen fixation, alkaline phosphatase, IAA, siderophore and exopolysaccharide production activity. Soil pot assays have shown the applicability of PGPR isolates in bioremediation of saline soil in restoring the fertility of soils. A four-factorial design was prepared for experimental set up to test the effect of PGPR inoculum on soil properties as well as plant growth. Common Sugar cane (Saccharum officinarum) was selected as the experimental plant species. Application of soil based PGPR after growing Sugar cane in saline soil resulted in increased physical properties of soil and also crop growth as compared to non inoculated soils. Change in pH, EC and SAR obtained with PGPR inoculation could be attributed to microbial activities in such soils. Improved growth of Sugar cane has suggested that halotolerant PGPR enriched soils with carbon, nitrogen, other nutrients and physicochemical properties.
