ABSTRACT

This study aimed to develop a rhizobial consortium to enhance the growth and yield of summer green gram crops. Green gram, the major legume crop, commonly called as mung bean is cultivated majorly during dry and semi-arid regions of India accounting to the yield level of 609 kg/ha. The bacterial genus Rhizobium is a free living rhizobacteria has symbiotic relationship with legume crops and form’s nodules, where it convertes atmospheric N2 into ammonia. The present research involved isolating and characterizing efficient Rhizobium strains from soil and root samples collected from Dharwad district. Out of 125 isolates obtained, 30 were tentatively identified as Rhizobium species based on morphological, biochemical tests and conformed by description in Bergey’s manual of determinative bacteriology. These isolates were further evaluated for their plant growth-promoting properties, including ammonia and IAA production, HCN and siderophore production and antifungal activity against pathogens. Six isolates with superior functional characterization capabilities namely, HR-73, BR-29, MR-26, MR-16, HR-82, HR-69 were selected and tested for compatibility with plant growth-promoting rhizobacteria (PGPR) strains AUDP-203 and AUDP-279. Out of 6 isolates tested, only HR-73 and BR-29 were compatible with all test bacterial strains and used for developing a liquid consortium. A total of six liquid consortium were formulated in various combinations using equivalent population HR-73, BR-29, AUDP-203, AUDP-279, NC-92 bacterial strains. Greenhouse trials under conditions simulating summer stress revealed that the M-7 (HR-73+ BR-29+ AUDP 203 + AUDP 279) consortium significantly improved plant growth, biomass, physiological traits and yield parameters in green gram genotypes DGGV-2 and DGG-96. Enhanced plant growth and soil health might be due to synergistic effects of consortium. The study demonstrated the potential of combining Rhizobium strains with PGPR to boost green gram productivity, providing a promising strategy for sustainable agriculture and improved crop performance.