Isolation and Characterization of Plant Growth Promoting Rhizobacteria and Their Effects on Non-Leguminous Plant Growth and Soil Properties

Synthetic fertilizers especially nitrogen (N) and phosphorus (P) based are critical to increase the productivity of agricultural land to meet the increasing demand for food. However, the use of N and P fertilizer commonly results in nitrate leaching and P run-off, which degrades ground water quality and exacerbates eutrophication in surface water. Therefore, the aim of this study was to isolate plant growth-promoting rhizobacteria (PGPR) and their utilization as biofertilizer to improve non-leguminous plant growth. We isolated PGPR from different plants rhizosphere soil and plant growth enhancing characterization of these isolates were assessed. Out of 10 isolates, seven of them exhibited PSB (Phosphate Solubilizing Bacteria) traits in Pikovskaya media by solubilizing phosphate and the phosphate solubilization index was 4.4-6. Among them, two isolates showed positive results for three growth promoting activities (Indole acetic acid (IAA) production, Phosphate solubilization, Non symbiotic nitrogen fixation). A pot experiment with twenty five treatments for Amaranthus cruentus revealed that inoculation of PGPR increased growth of Amaranthus cruentus and improved soil properties. The isolate from Yardlong bean significantly increased plant height and fresh weight biomass by 85% and 194% respectively, compared to uninoculated control. Further field trial is required to evaluate their efficiency as potential biofertilizers.