Screening of plant growth promoting rhizobacteria for sustainable wheat (Triticum aestivum l.) crop production

The study was conducted to isolate and characterize wheat plant growth promoting rhizobacteria (PGPR). The isolation was carried out at tillering stage of wheat crop. The potential of wheat for colonizing different microbes at different combinations of organic and inorganic nutrient sources was determined. Overall, the microbes were more abundant in rhizosphere as compared to non-rhizosphere soil. The highest population of bacteria 9.64 log (cfu g^-1 soil) and N₂ fixing bacteria 7.67 log (cfu g^-1 soil) were found in the rhizosphere of wheat where 50 kg N and 33 kg P₂O₅ ha^-1 integrated with FYM 9 t ha^-1. However, the most phosphate solubilizing bacteria 9.08 log (cfu g^-1 soil) was recorded at sole application of FYM (9 t ha^-1). A total of 24 potential isolates varying in colony morphology were screened for further characterization. Most of the PGPR exhibited the capability of nitrogen fixation, P solubilization and IAA production. The P solubilization efficiency ranged from 11.14 to 75.00% with the highest recorded in NIA-PGPR1 (75%). The screened isolates produced indole-3 acetic acid (0.88-8.92 mg L^-1) with the highest IAA production of 8.92 mg L^-1 in NIA-PGPR9. All PGPR strains also had the abilities of biofilm formation. Ten (10) most efficient PGPR isolates were selected for evaluation in enhancing wheat growth under laboratory conditions. All inoculated PGPR isolates positively affected wheat plant growth. The highest plant height (31.5 cm) was observed in plants inoculated with NIA-PGPR1 while maximum root length (8.5 cm) and plant dry biomass (0.172 g) was recorded in NIA-PGPR5. The screened bacterial strains have plant beneficial characters and have potential for development of bio-product in order to enhance wheat plant growth in a sustainable manner.