Microbial functions of the rhizosphere

Abstract

The rhizosphere is part of the soil surrounding the plant roots or being influenced by the plant roots. The exudates released from roots make it a site for complex biochemical activity. Microorganisms make up one of the dynamic parts of this rhizosphere, and affect soil and plant growth by various means. However, our absolute dependency on chemical fertilizers and other agrochemicals, although enhancing crop production to the desired levels required to feed the growing world population, has not shown sufficient concern for sustainability, leading to two serious problems, ecological imbalance and resource limitation. An ecological disturbance has been created through polluting soil and water, putting toxic agrochemicals into the food chain, threatening human and animal health, and developing resistance in pests. On the other hand, resources are diminishing as vital nutrients like phosphorus are limited and very soon there will be an extreme shortage of these nutrients because excessive consumption will make them no longer available. Therefore, balancing plant needs through microbe-mediated sources is becoming an urgent priority. The rhizosphere microflora have many beneficial effects on plant growth and health promotion. They can be successfully employed to partly substitute agrochemicals in the long term for sustainable farming. Understanding the roles of these microbes therefore becomes imperative for enhancing quality and quantity of agricultural products. In the quest to improve productivity, management of rhizosphere dynamics provides an important tool. Inoculation of microorganisms, adjustment of soil, nutrient management, genetic engineering-based approaches, etc. all represent ways of managing the rhizo- sphere for enhancing crop production.