Influence of plant growth-promoting bacteria on the growth performance of common bean (Phaseolus vulgaris L.)

Rapid population growth, expanding urbanization and industrialization are placing colossal pressure on agricultural systems by reducing cultivable land, degrading soil quality and increasing dependence on synthetic chemicals to meet global food demands. Plant growth-promoting bacteria have emerged as promising eco-friendly alternatives capable of enhancing plant growth and supporting sustainable agricultural production. The present study was undertaken to isolate multifunctional PGPB from soil and evaluate their growth-promoting potential in Phaseolus vulgaris L. Bacteria obtained using serial dilution techniques were purified and screened for important plant growth-promoting traits. A total of 19 bacterial isolates were obtained, among which three isolates, namely AB1051, AB1054 and AB1056, exhibited all the tested plant growth promoting traits. Seed germination assays showed that isolates AB1051 and AB1054 achieved 100% germination, whereas AB1056 and the control recorded 38.89% and 55.56% germination, respectively. Isolate AB1054 showed the best performance with the highest shoot length (20.77 ± 0.46 cm), root length (9.20 ± 0.30 cm) and number of leaves (11.67±0.58). The same isolate also recorded the highest shoot fresh weight (16.56±0.25 g), root fresh weight (2.30 ± 0.23 g), shoot dry weight (0.78±0.01 g) and root dry weight (0.19±0.00 g). Molecular characterization based on 16S rRNA gene sequencing showed highest sequence similarity of isolate AB1054 with Acinetobacter sp. The strong multifunctional plant growth-promoting traits and greater effects of isolate AB1054 indicate its promising potential as a bioinoculant for sustainable bean cultivation and reduced dependence on synthetic fertilizers.