The Role of Micronutrients in Plant Metabolism & Growth and Diagnostic Tools to Assess Micronutrient Deficiencies

Despite the fact that micronutrients are required in very low concentrations by plants, they are as essential for plant metabolism and growth as macronutrients. Foliar analysis is a valuable tool in order to detect micronutrient deficiencies before macroscopic symptoms appear in plants; for that purpose, critical micronutrient concentrations have been established. Other diagnostic tools used to assess micronutrient deficiencies are soil analysis, plant-growth response (in annual plants), and visual observation of symptoms. Recently, more and more biochemical indicators, as early detectors of micronutrient deficiencies, are used. Fertilization (soil or foliar application) should be included in the cultivation program in order to improve the low nutritional status of plants. However, before fertilization, it is absolutely necessary to have a deep knowledge of the physiological roles of the necessary micronutrients for normal plant growth. So, the physiological roles of micronutrients, as well as some critical deficiency concentrations in soils and plants, are presented in detail and fully discussed in this chapter.

Keywords: Critical concentrations, foliar deficiency symptoms, micronutrient deficiency, micronutrient sufficiency, plant growth, plant metabolism, physiological roles.