Wheat (Triticum aestivum L.) growth promotion by halo-tolerant PGPR-consortium

Salinity is among the major environmental factors that significantly affects the global crop production. Inoculation with plant growth promoting rhizobacteria (PGPR) increases crop productivity because PGPR convert the un-available forms of nutrients to plant-available form. With the aim to develop saline-soil specific biofertilizer, bacteria were isolated from rhizosphere of wheat grown in saline soil (EC 7.63 dS m(-1)). Of total 21, eight bacteria showed halophilic (up to 65g L-1 NaCl), and four showed alkaliphilic (up to pH 9.5) trait; 12 isolates produced indole-3-acetic acid (411.5-9.33 mg L-1), 15 bacterial isolates solubilized inorganic fri-calcium phosphate (17.5-6.7 mg L-1), 14 isolates exhibited ACC-deaminase activity, and only one isolate solubilized the insoluble ZnO. A consortium of three potential PGPR strains (SAL-12, SAL-17, SAL-21; having multiple PGP traits) was tested for two years in laboratory and field experiments for wheat productivity with half dose of chemical fertilizer (NPK) under induced and natural salinity. The comparison of results with a non-halophilic wheat inoculum (BioPower containing Azospirillum and Pseudomonas spp.) indicated that both halo-tolerant and non-halo tolerant PGPR-consortia with reduced fertilizer dose have potential to increase the growth and yield of wheat in saline conditions. The relative increase in yield induced by halo-tolerant consortia was however, significantly better as compared to non-halo-tolerant PGPR inoculum that may be attributed to salt tolerance potential and stable PGP activities of PGPR indigenous to stressed environment. The study suggests using eco-friendly, cost-effective PGPR-biofertilization (inoculation) technology for wheat productivity in saline environments with reduced application of chemical fertilizers.