Isolation and Evaluation of Rhizobium Strains Associated with Vigna sesquipedalis and Their Plant Growth-Promoting Potential

Vigna sesquipedalis, commonly referred to as yard long bean, is a vital leguminous crop that depends on symbiotic nitrogen fixation mediated by Rhizobium species. The present study focuses on the isolation and characterization of Rhizobium from rhizosphere soil and the evaluation of its plant growth-promoting (PGP) attributes. The isolated strains were cultivated on Yeast Extract Mannitol Agar (YEMA) medium and analysed through morphological and biochemical tests. A pot culture experiment was carried out to examine the impact of various inoculation methods such as soil treatment, seed treatment, and a combination of both on the growth and yield of Vigna sesquipedalis. Plant Growth Promoting traits assessed included phosphate solubilization, indole-3-acetic acid (IAA) production, and nitrogen fixation efficiency. The outcomes of this study aim to demonstrate the potential of Rhizobium as an effective biofertilizer, offering a sustainable alternative to chemical fertilizers. This research underscores the importance of microbial inoculants in enhancing crop productivity and improving soil fertility, thereby promoting environmentally sustainable farming.