Plant growth-promoting rhizobacteria as sustainable bio-inputs for modern agriculture: A critical review

These beneficial rhizospheric microorganisms enhance plant growth through multiple direct and indirect mechanisms, including biological nitrogen fixation, phosphate solubilization, phytohormone production, siderophore release, and suppression of plant pathogens. In the context of modern agriculture, where sustainability, climate resilience, and resource-use efficiency are critical, PGPR offer eco-friendly alternatives to conventional agro-inputs. This review critically examines recent advances in PGPR research, focusing on their functional mechanisms, role in nutrient acquisition, stress tolerance enhancement, and disease management. Special emphasis is given to their performance under abiotic stresses such as drought, salinity, and heavy metal contamination, which are increasingly prevalent under changing climatic conditions. Furthermore, challenges associated with PGPR commercialization, field-level consistency, formulation stability, and regulatory constraints are discussed. Emerging trends, including omics-based PGPR characterization, microbiome engineering, and integration with precision agriculture technologies, are also highlighted. The review concludes by identifying key research gaps and future prospects for large-scale adoption of PGPR as sustainable bio-inputs in modern agricultural systems. Overall, PGPR represent a vital component of next-generation sustainable agriculture, contributing to improved crop productivity, soil health, and environmental sustainability.