Plant Growth-Promoting Rhizobacteria (PGPR) in Sustainable Crop Production

Plant rhizosphere is defined as the zone of the soil surrounding the plant roots with a diversity of microorganism associated with it. The rhizosphere is strongly influenced by the plant due to release of various substances known as root exudates that consists of vitamins, carbon dioxide, organic acids, amino acids, etc. The rhizosphere harbors diverse microflora that performs various functions like nutrient cycling, solubilization, and protection from environmental stress conditions. There are evidences that interaction between plant and microbes can be advantageous for plant in terms of growth and productivity. A heterogeneous group of bacteria that are associated with root surfaces are called as plant growth-promoting rhizobacteria (PGPR). Though the rhizosphere has a diversity of microorganisms, bacteria are largely accepted for the sustainable growth and development of plant. Various evidences have proved that PGPR are successful inoculants in agriculture. In addition to the positive effects on plant growth, PGPR can also help the plant to fight against several phytopathogens. Due to the ability of rhizobacteria to produce growth regulators like indole-3-acetic acid (IAA), nitrogen fixation, and solubilization of insoluble minerals like phosphorus, potassium, silicon, and zinc, they have got worldwide acceptance as compared to other microorganisms for enhancing the growth of plant. Also, some act as the biocontrol agent to the plant pathogens.