Chapter 7 - Function of Nutrients: Micronutrients

Abstract

Publisher Summary This chapter focuses on the functions of iron, manganese, copper, zinc, nickel, molybdenum, boron, and chlorine in plants and describes the effects of their deficiency and toxicity. Iron (Fe) plays a crucial role in redox systems in cells and in various enzymes. In dicotyledonous and monocotyledonous plant species, Fe deficiency is associated with the formation of rhizodermal transfer cells, which is a part of a their strategy to enhance iron uptake. Manganese (Mn) and copper (Cu) are important for redox systems, as activators of various enzymes including those involved in the detoxification of superoxide radicals, and for the synthesis of lignin. In dicotyledonous plants, intercostal chlorosis of the younger leaves is the most distinct symptom of Mn deficiency, whereas in cereals, greenish grey spots on the older leaves are the major symptoms. Stunted growth, distortion of young leaves, chlorosis/ necrosis starting at the apical meristem extending down to the leaf margins, bleaching of young leaves, and/or “summer dieback” in trees are typical visible symptoms of Cu deficiency. Zinc (Zn) plays a role in the detoxification of superoxide radicals, membrane integrity, as well as the synthesis of proteins and the phytohormone IAA. Nickel (Ni) is involved in N metabolism as a metal component of the enzyme urease, whereas molybdenum (Mo) helps in N metabolism by acting as a metal component of the nitrogenase (N2 fixation) and nitrate reductase enzymes. Boron (B) is crucial for cell wall and membrane integrity, whereas chlorine plays a role in osmoregulation and stomata movement.