Plant Growth Promoting Rhizobacteria‐Mediated Amelioration of Abiotic and Biotic Stresses for Increasing Crop Productivity

Abstract

Several microbes with ability to promote plant growth and their products that can stimulate plant growth have been commercialized. This chapter is mainly restricted to the bacteria that are derived from plant rhizosphere and demonstrate their beneficial effects on the root. Such group of bacteria is generally designated as PGPR (plant growth promoting rhizobacteria). Beneficial effects of this group of rhizobacteria on plant growth can be demonstrated by both direct and indirect mechanisms. Various abiotic and biotic stresses negatively influence survival, biomass production, and crop yield. This chapter begins with the description of various abiotic and biotic stress factors affecting plant growth. Tolerance to these stresses is achieved by both physiological and molecular level adaptation. To exert the beneficial effects, bacteria must colonize the root surface efficiently as the roots are the first underground part of the plant system that experiences adverse conditions. Mechanisms of abiotic and biotic stress amelioration in the rhizosphere by PGPRs are subsequently described. PGPRs often have more than one mechanism for enhancing plant growth and experimental evidence suggests that the plant growth stimulation is the net result of multiple mechanisms of action that may be activated simultaneously. Thus, to fulfill the need of food production for ever-increasing global population under extreme environmental conditions or with limited sources, PGPRs are surely a major target to be developed for the improvement of tolerance to stresses.