Copper

Copper is involved in many physiological processes in plants, including photosynthesis, protein synthesis, protein metabolism and cell wall strength. Copper is commonly used as an enzyme cofactor, meaning it enables the plant to function properly. A copper deficiency causes deterioration of the cell wall structure, causing among others, twisting flag leaves, leaf decolouration and increased seed abortion. When the concentration of copper is too high, it turns into a toxicant due to its ability to catalyse free radicals in the plant. This can cause anatomical and physiological changes, which decreases both food productivity and quality. Copper has the interesting quality that its concentration is related to the concentration of another trace metal – zinc. When the concentration of copper in soil increases, the concentration of zinc decreases, and vice versa. 

Hooda, P. (2010). Trace elements in soils. Wiley.