PLANT GROWTH PROMOTING RHIZOBACTERIA AND THEIR SCREENING, CHARACTERIZATION AND ENHANCING SEED GERMINATION IN MUNG BEAN (VIGNA RADIATA L.)

Global food security is increasingly challenged by a growing population, shrinking agricultural land, and climate change. Utilizing Plant Growth-Promoting Rhizobacteria (PGPR) as bio-stimulants offers a sustainable strategy to enhance crop productivity. The present study aimed to isolate, screen, and characterize efficient PGPR from the rhizospheric soil to improve the seedling vigour and germination of mung bean (Vigna radiata). Rhizospheric soil samples were collected to isolate bacterial strains, which were subsequently evaluated for vital plant growth-promoting (PGP) attributes. Screening criteria included Indole Acetic Acid (IAA) synthesis. Furthermore, the isolates were tested for phosphate solubilization, siderophore production, ammonia production, and biocontrol traits such as Hydrogen Cyanide (HCN) production. The most promising isolates were then evaluated in vitro for their impact on mung bean seed germination and Seed Vigour Index (SVI) over a 7-day period. Out of the isolates screened, seven efficient strains demonstrated superior PGP potentialities. Notably, the most potent isolates, PBN13 and PGY11, exhibited high levels of phosphate solubilization and IAA production. In vitro assays revealed that bacterial inoculation significantly augmented seedling development; isolate PBN13 achieved a maximum germination rate of 97.33% and a Seed Vigour Index of 1499.85. This represents a 148.89% increase in Vigour Index over the uninoculated control (SVI = 602.61), a result that highlights the efficiency of these strains in accelerating early plant development. The rhizobacterial isolates PBN13 and PGY11 possess a robust suite of PGP attributes, making them promising candidates for the formulation of biofertilizers. These results suggest that such PGPR-based applications can effectively enhance crop improvement and protection, supporting the transition toward sustainable agricultural practices.