Plant growth promoting rhizobacteria in sustainable agriculture: from theoretical to pragmatic approach

Plant growth promoting rhizobacteria (PGPR) are the residents of rhizosphere that are known to influence plant growth and survival through the production of various regulatory chemicals under a variety of circumstances. This growth promotion is accomplished by both direct and indirect means. Direct effects of PGPR encompass two major activities, that is, Bio-fertilization (Enhancement of nutrient uptake including nitrogen and phosphorous primarily) and phytostimulation (Production of plant growth promoting hormones). Indirect effects of PGPR are majorly contained within their ability as biocontrol agents that antagonize the growth and survival of phytopathogens either by the production of antagonizing chemicals (Local antagonism) or by the induction of systemic resistance throughout the plant against pathogens. The understanding of such diverse growth promoting abilities of PGPR has led to their application as potent biofertilizers for sustainable agriculture. However, further analyses of the agro-ecosystem with complex biotic and abiotic mechanisms should not be overlooked for their extensive commercial applications and future prospects.