Harnessing Native Synergy: Screening And Evaluation Of Multi-Spectrum Indigenous Rhizobium Strains For Sustainable Agriculture

The increasing demand for food production and the environmental impact of excessive chemical fertilizer use call for the development of sustainable agricultural alternatives. Among plant growth–promoting rhizobacteria (PGPR), Rhizobium plays an important role in improving soil fertility through biological nitrogen fixation and multiple plant growth–promoting activities. However, the inconsistent performance of commercial inoculants under varying agro-climatic conditions highlights the need to identify efficient indigenous strains adapted to local soils. In this study, nodulated root samples from major leguminous crops including pigeon pea, black gram, cowpea, peanut, and mung bean were used for the isolation and characterization of indigenous Rhizobium strains. The isolates were cultured on yeast extract mannitol agar and evaluated through microscopic, biochemical, and metabolic analyses to identify multi-spectrum strains possessing traits such as PO₄ and K solubilization, phytohormone production like IAA and cytokinin, and nutrient mobilization. Selected isolates showed compatibility with native soil microbiota and significantly enhanced nodulation, plant growth, biomass accumulation, and overall vigor in Fenugreek under controlled pot conditions, both individually and as microbial consortia. Changes in plant protein expression patterns further indicated enhanced metabolic activity following microbial inoculation. The findings demonstrate the ecological and agronomic potential of indigenous Rhizobium strains as effective biofertilizers capable of reducing dependence on synthetic fertilizers while improving crop productivity and soil health. These results support the use of region-specific microbial resources for environmentally sustainable agricultural practices.