Plant Mineral Nutrition.
Several inorganic minerals are essential for plant growth and these are usually obtained by roots from the soil. Availability of minerals in the soil is determined by the physical and chemical characteristics of the soil. Plants can directly influence nutrient availability around the root surface; this zone is called the rhizosphere. Plants adjust root architecture and exudation according to their nutrient requirements and under deficiency these changes can be a marker for nutrient status. Nutrients are taken up from the soil using plasma]membrane located transporter proteins and excess is stored in the cell vacuole or converted into polymerised storage forms. For crops it is essential to match nutrient supply to demand throughout the growth season to obtain the maximum yield. These nutrient storage forms can be used as agricultural indicators of crop nutrient status and the potential for fertilizer leaching losses. Membrane transporters provide a gateway for nutrient entry into plants, but the selectivity of these filters can breakdown when chemically similar minerals are present at very high concentrations. The minerals may not be essential for growth, but they can enter plant cells and cause toxicity.