Plant Growth Promoting Rhizobacteria: Principles and Utilization

Abstract

Plant growth promoting rhizobacteria (PGPR) discovered in the rhizosphere area. PGPR are intracellular PGPR (iPGPR) existing symbiotic relationship such as root nodule bacteria and extracellular PGPR (ePGPR) existing free living in the soil such as bacteria existing near the root. PGPR have specific properties such as 1) colonize the root surface, 2) control of plant pathogens and 3) tolerant to drought, salinity, heat and ultraviolet radiation. Also, PGPR have promote growth by direct mechanism such as nitrogen fixation, phosphate solubilization, potassium solubilization, phytohormone production, and root development and indirect mechanism such as antibiotic production, siderophore production, environmental tolerance and heavy metal tolerance. From beneficial properties as mentioned above, PGPR were brought to biofertilizer products by Department of Agriculture has developed including 1) rhizobium biofertilizers, 2) PGPR biofertilizers have three products such as PGPR-1 biofertilizer (for maize and millet), PGPR-2 biofertilizer (for rice), PGPR-3 biofertilizer (for sugarcane and cassava) and 3) phosphate solubilizing biofertilizer. When used the rhizobium, PGPR, and phosphate biofertilizers with crop production could be decreased the chemical fertilizers are less than 50, 25 and 25-50 percentages, respectively. Furthermore, the use of biofertilizers can be increased crop healthy and yield for farmers.