Source. Zinc occurs in ferromagnesium minerals, magnetite, biotite etc. When weathering of these minerals takes place, zinc is liberated in bivalent Zn2+ form. Increase in soil pH decreases the availability of zinc.
Regions. In plant zinc is required everywhere.
Functions. It activates many enzymes especially carboxylases, part of carbonic anhydrase and various dehydrogenases. It takes part in the formation of tryptophan which is a precursor of auxin IAA.
Deficiency symptoms
(i) Distortion of leaves.
(ii) Reduction in fruits and seeds.
(iii) Formation of smaller leaves and shortened internodes.
(iv) It causes disease like ‘little leaf of deciduous fruit trees’.