PGPR (Biofertilizers & Biofungicides) are Plant Growth-Promoting Rhizobacteria defined as root-colonizing bacteria that exert beneficial traits on plant growth and development.
Root colonization comprises the ability of PGPR to establish on or in the root or rhizosphere to multiply, survive and colonize along the growing root in the presence of the indigenous microflora. PGPR are considered as efficient microbial competitors in the soil-root zone. Genera of PGPR generally include Acinobacter, Agrobacter, Arthrobacter, Azospirillum, Bacillus, Bradyrhizobium, Frankia, Pseudomonas, Rhizobium, Serratia, Thiobacillus, and others. In addition to plant growth promotion, PGPR are also used for controlling several plant pathogens, enhancement of nutrient up-take and in rhizomediation. PGPR colonize plant roots and exert beneficial effects on plant growth and development by a wide variety of mechanisms. To be an effective PGPR, bacteria must be able to colonize roots because bacteria need to establish itself in the rhizosphere at population densities sufficient to produce the beneficial effects.
The exact mechanism by which PGPR stimulate plant growth is not clearly established, although several hypotheses such as production of phytohormones, suppression of deleterious organisms, activation of phosphate solubilization, and promotion of the mineral nutrient uptake are usually believed to be involved.
In the context of increasing international concern for food and environmental quality, the use of PGPR for reducing chemical inputs in agriculture is a potentially important issue. PGPR have gained world-wide importance and acceptance for sustainable agricultural benefits. PGPR’s are the potential tools for future of sustainable agriculture. Currently, there is an active and growing group of researchers working on fundamental and applied aspects of PGPR. The application and commercialization of PGPR for sustainable agriculture is a growing and demanding market world-wide.