Nutrient Acquisition and Soil Fertility: Contribution of Rhizosphere Microbiomes in Sustainable Agriculture

Abstract

Recent application of modern agricultural biotechnologies and use of high-yielding crop varieties provided sufficient crop yields and food for human population. But, the major constraint to enhance crop yield and food production is the availability of various nutrients in the soil, which include nitrogen, phosphorus, potassium, sulphur, zinc and other micronutrients. Currently, chemical fertilizers and plant growth regulators are widely utilized for obtaining high crop yields. However, the injudicious application of fertilizers along with other agrochemicals has resulted in environmental pollution along with deleterious effects on beneficial microflora and fauna. Recently, soil-inhabiting beneficial microorganisms are screened and exploited for use as biofertilizers to enhance soil fertility and crop yield with reduced application of chemical fertilizers. Thus, the use of microbial inoculants has emerged as novel agrobiotechnology for attaining sustainable agricultural production systems. These beneficial microorganisms contribute immensely towards management of plant nutrients in the soil by way of nitrogen fixation, solubilization of phosphorus, potassium and zinc along with other nutrients. Other beneficial characteristics of microbial inoculants include phytohormones production, inhibition of phytopathogens’ growth, bioremediation of pollutants and heavy metals, and amelioration of abiotic as well as biotic stresses. However, the efficacies of microbial inoculants in improving crop yield under field conditions remain variable under varied farming situations in different agro-ecosystems. Recently, genetic engineering techniques are being employed to improve the beneficial traits in plants and microorganisms to improve nutrient availability, soil fertility and crop yield. In addition, identification of effective microbial inoculants and their persistence in soil and quality of these inoculants is a never-ending process for harnessing desirable impacts on crop productivity. Considering the importance of beneficial microorganisms in biogeochemical cycling of nutrients, various mechanisms involved in improving nutrients availability are reviewed for increasing food production.KeywordsMicrobial inoculantsNutrient acquisitionRhizospheric microorganismsPhytohormonesInduced systemic resistance