Enhancement potential of plant growth-promoting rhizobacteria on white beans (Phaseolus vulgaris) seedlings

The effect of inoculating single cultures of plant growth-promoting rhizobacteria (PGPR) on development of white beans seedling (Phaseolus vulgaris) was analyzed. Five PGPR were isolated from the rhizosphere of Okra plants and were assessed for abilities to solubilise phosphate and produce indole acetic acid (IAA). The phosphate solubilising index ranged from 6-10 while the concentration of IAA ranged from 17.48mg/l to 27.43mg/l. Serratia sp. produced the highest concentration of IAA (27.43mg/l) and had the highest solubilisation index (10mm). Bacillus sp. produced the least amount of IAA (17.48mg/l) while Staphylococcus sp. had the least solubilisation index (6mm). The highest percentage germination of 83.3% was observed in the seedling inoculated with Bacillus sp. The effect of PGPR on root and shoot elongation was studied hydroponically for 7 days. Significant increases (P< 0.05) in root elongation were observed.. The highest seedling root length (18.47cm) and shoot length (19.17cm) were observed with inoculation of Staphylococcus sp. and Bacillus sp. respectively. The use of these bacteria as bio-inoculants could be a sustainable practice to facilitate nutrient supply to white beans seedlings.