Iron, Manganese and Copper are essential micro nutrients needed in very small amount to the plants.
IRON - Plants obtained iron in the form of ferric ions (Fe3+ ), is an essential micro nutrient required in large amount in comparison to other micro nutrients. It is reversibly oxidised from Fe2+ to Fe3+ during electron transfer. It activates catalase enzyme and is essential for the formation of chlorophyll.
MANGANESE - Manganese is one of the essential micro nutrient and is absorbed in the from of manganous ions (Mnā2+). During the process of photosynthesis it plays a role in splitting of water to liberate oxygen also it activate many enzymes involved in photosynthesis, nitrogen metabolism and respiration.
COPPER - It is absorbed cupric ions (Cu2+), and is essential for the metabolism of plant. Like iron copper is associated with enzymes such as ascorbic acid oxidase, tyrosine, monoamine oxidase, uricase etc. involved in redox reaction and is reversibly oxidised from Cu+ to Cu2+.