Functionalities of Phosphate-Solubilizing Bacteria of Rice Rhizosphere: Techniques and Perspectives

Abstract

Phosphorus (P) is the second essential macronutrient next to nitrogen. It is a constituent of the essential macromolecules like DNA, RNA, ATP, phospholipids, etc. and indispensable at all growth stages of all plants. With rice being the staple cereal diet of about 50% in the world and 85% of the Indian population and P being an essential plant nutrient, understanding P metabolism in rice rhizosphere is important to assess fertility status of rice soils. Oxidation-reduction reactions in rice soil open up challenges, opportunities and potentials for manifold microbial activities which are significant for maintenance of fertility and sustainability in rice production systems. Rice production should be enhanced to meet the world food need. Most agricultural soils are P deficient and, therefore, require application of phosphatic fertilizers to sustain crop production. But excess chemical P fertilizer application can cause environmental hazards like pollution, eutrophication, etc. This situation warrants for eco-friendly and economical alternate strategy like biofertilizer application for improving crop production in P-deficient soils. Phosphate-solubilizing microorganisms, viz. Bacillus, Pseudomonas, Azotobacter, Aspergillus spp. etc. can mineralize insoluble P thereby increasing P availability to plants. Therefore, efficient P-metabolizing biofertilizer application would promote plant growth, improve soil health and protect plants from different pathogens without disturbing the environment.