COMPREHENSIVE REVIEW ON PLANT GROWTH PROMOTING RHIZOBACTERIA IN RELEVANCE TO ABIOTIC STRESS TOLERANCE OF PLANTS

The rhizosphere represents an intricate microenvironment, consisting of a complex network involving soil, root and soil microbes. Conditions in the rhizosphere exert a direct influence on the growth and yield of crops. The unregulated and widespread application of synthetic fertilizers has emerged as a grave concern for the sustainability of agriculture and the equilibrium of ecosystems. These chemical substances accumulate within the soil, leach into water sources and release into the atmosphere, persisting for decades and posing a substantial threat to the overall ecosystem. This issue is of significant concern, necessitating a potential solution that can only be realized through the involvement of microorganisms and organic amendments. Plant growth promoting rhizobacteria (PGPR) has assumed a pivotal role in addressing this concern. The established role of microorganisms in enhancing plant growth, managing nutrients and exerting biocontrol is well -documented. PGPR, present in the rhizosphere, has the capacity to transform numerous nutrients that are initially inaccessible to plants into forms that can be readily utilized. Additionally, PGPR synthesize plant hormones, secondary metabolites, antibiotics, stressrelieving compounds, chelating agents, and signaling molecules, enabling interactions with both beneficial and pathogenic organisms within the rhizosphere. Moreover, PGPR is involved in the improvement of soil physical properties, chemical properties and overall functioning that offers direct or indirect benefits to crop growth.