Zinc plays a vital role in many functions within the plant. One of the well-documented functions of Zn is its role in protein synthesis and its contribution to the structural integrity of a number of proteins. Zn deficiency results in a severe decline in protein biosynthesis. Up to 10% of the proteins in biological systems need Zn for their proper functioning and for the maintenance of their structural integrity. It is therefore not surprising that plants show a high susceptibility to low concentrations of Zn in tissues.
Other important functions of Zn in plant cells are: Structural and functional integrity of cell membranes, Detoxification of reactive oxygen species (ROS), Photo-oxidation and light damage (destruction of chlorophyll), Synthesis and protection of IAA (a hormone that controls plant growth and development), Reducing cadmium accumulation in plants.
The structural integrity of cell membranes is important also for protecting plants against pathogenic infections. Exudates from ‘leaky’ cells create an environment ideal for the growth and invasion of root cells by fungi and bacteria.
The most common symptoms of zinc deficiency in maize include the development of whitish or yellowish stripes parallel to the midrib on the young leaves and stunting appearances with shortened internodes. Necrotic spots and reddish colour may develop on leaves as the deficiency develops.
Data from samples analysed by Yara Analytical Services in 2019 show that 53% of maize leaf samples were deficient in zinc so around half of all maize crops might not reach their potential.