Focus on nutritional elements: copper 

30 AUGUST 2018

The trace element copper is a building brick of enzymes that are indispensable for many plant processes, especially the regulation of hormones. This time in ‘Focus on nutritional elements’ everything about copper.

What is the function of copper? 

Similar to zinc, copper can be taken up as copper ion (Cu2+) and in chelate form. The uptake of copper is usually larger in the vegetative phase than in the generative phase of the plant. Copper is hardly mobile in the plant. Just like other trace elements, copper is a building brick of enzymes. Enzymes are indispensable for many processes in the plant. The level of copper in the plant is approximately between 0.0001 and 0.0006 % of the dry matter.

In what shapes does copper occur? 

Copper is added to most potting soil base fertilizers. The level of copper added needs to be relatively high in order to obtain enough copper in the solution. In base fertilizing and regular fertilizing copper is usually added as copper sulphate. This is because in organic substrates, a large part of the copper is bound by the organic matter. Copper can play a role in chelate exchange with iron chelate. But this usually doesn’t lead to problems.

What is the effect of copper? 

Copper plays an important part in the hormone regulation of plants. When there is a copper deficiency, the so-called IAA hormone will pile up in the plant. This disrupts the hormone regulation as such, that it will lead to odd growth. A plant with a copper deficiency is characterized by a sturdy growth and a different, blue green crop colour. The crop can also become ‘bushy’ and a disruption of flowering can occur. Odd growth, like twisting of the leaves, is often caused by copper deficiency. Sometimes a crop with a copper shortage shows the same symptoms as for water deficiency. Berberis, Juniperus and Cotoneaster can be sensitive to copper deficiency. Copper toxicity  is not common. When there is an excess, the roots will start to look like ‘barbed wire’ and it will lead to chlorosis (decomposition of chlorophyll) of the leaves.

What are the RHP requirements for copper? 

Copper is added to most potting soil base fertilizers. Among others, the copper level in RHP certified products is checked before application in a substrate. There is a maximum copper level for growing media with the RHP Horticulture quality mark. Within that norm, the substrate producer and the grower will decide together what the copper level needs to be, suitable to the culture.

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