The actions of PGPR on micronutrient availability in soil and plant under calcareous soil conditions: An evaluation over Fe nutrition

The autotrophic plants need minerals for life cycle. An adequate supply of mineral nutrients is necessary for optimum plant growth. However, when adequate amounts of essential nutrients are present in soil, plants may still show deficiencies due to the non-availability of these mineral nutrients. Availability of plant nutrients such as Fe, Mn, Cu, B, and Zn are generally low in calcareous soils. Fe deficiency-induced chlorosis is the main limiting factor restricting plants growing worldwide. Microorganisms play an important role in enhancing nutrient availability to plant roots. Some PGPR increase the Fe availability in soil by decreasing pH by releasing organic acids or synthesizing low-molecular-weight iron-chelating agents (siderophores). In addition, some PGPR may increase Fe translocation and availability in plants via enhancing organic acid contents and FC-R activity in the root and leaves.