PGPR Interaction: An Ecofriendly Approach Promoting the Sustainable Agriculture System

Soil, the dynamic and valuable natural resource harbouring a vast collection of microorganisms, is vital for the production of food and fibre, in addition to fulfilling critical roles in the maintenance of global nutrient balance and ecosystem function. Plant growth promoting rhizobacteria (PGPR), a diverse group of soil bacteria, are key components of soil-plant systems, where they are engaged in an intense network of interactions in the rhizosphere, thus affecting the plant growth and yield. Agricultural productivity rests on the foundation of microbial diversity in the soil, and in recent years, PGPR have emerged as an important and promising tool for sustainable agriculture. PGPR promote plant growth and development directly or indirectly, either by releasing plant growth regulators/phytohormones or other biologically active substances, altering endogenous levels of phytohormones, enhancing the availability and uptake of nutrients through fixation and mobilization, or reducing the harmful effects of pathogenic microorganisms on plants and/or by employing multiple mechanisms of action. Besides offering an economically attractive and ecologically sound route for augmenting the nutrient supply and protecting against soilborne pathogens, PGPR are the key players in efforts to preserve soil fertility. In this chapter, the different mechanisms of plant growth promotion rendered by the PGPR are discussed briefly, and the need for the development and commercialization of these PGPR for sustainable agriculture is emphasized.