ROLE OF SOIL RHIZOBACTERIA IN UTILIZATION OF AN INDISPENSABLE MICRONUTRIENT ZINC FOR PLANT GROWTHPROMOTION

Abstract

The crop yield production depends on different nutrients (macro and micronutrients), but because of the several anthropogenic and environmental factors, the plants face some micronutrient deficiencies. Among them, worldwide the zinc (Zn) deficiency are common (mainly in the arid and semi-arid regions characterized by calcareous soils). These elements have a high concentration in the soils of these areas, however, their absorbable concentration for the plant is low (because of several factors, such as high soil pH, lack of organic matter, high bicarbonate in soil solution, compaction and lack of soil aeration and high consumption of phosphorus fertilizers) and subordinate values of micronutrients would reduce crop efficiency and yield. To overcome the Zn deficiency, chemical fertilizers are used. Extreme usage of the chemical fertilizers decreases soil fertility and makes the crops more susceptible to disease. There are reports of potential for insoluble zinc dissolution in the soil by rhizospheric microbes. These microbes can increase the supplying of nutrients, including soil insoluble zinc, to the plant through mechanisms such as the proton secretions, production of siderophores and organic and mineral acids. In order to achieve sustainable agriculture and the use of environmentally friendly solutions, the microbial potentials and their metabolites, as environmentally friendly agents and their replacement by chemical compounds is of particular interest to overcome the problem of supplying zinc needed by plants in calcareous soils. This study critically evaluates the soil microbe’s effect on the insoluble zinc dissolution in the soil, which can increase the bioavailability of these elements for plants and prevent soil fertility reduction due to overuse of chemical fertilizers.