Role of Zinc in Plant Cultivation
Zinc (Zn), one of the essential micronutrients for plants, is needed in small quantities but crucial for their development. The normal level of zinc in leaf tissue is 15-60 ppm, and in the substrate, 0.10-2.0 ppm. Neither zinc deficiency nor toxicity occur frequently; However, both have a negative impact on the development and quality of crops.
What is zinc for?
Zinc is a key component in plants, it activates the enzymes responsible for the synthesis of certain proteins. It is used in the formation of chlorophyll and some carbohydrates, and in the conversion of starches into sugars; Its presence in foliar tissue helps plants to withstand low temperatures. It is essential in the formation of auxins, which contribute to the regulation of development and elongation of the stem.
Deficiency: As with most micronutrients, zinc is immobile; That is, the deficiency symptoms of this element are presented in the new leaves. These symptoms vary depending on each type of crop. They usually manifest as an inconsistent pattern of chlorosis (often intervening) in new leaves; In addition, necrotic spots may occur on the edges or at the tips of the leaves. These new leaves are smaller and often twisted upwards or deformed. The internodes are shortened, giving the plant a rosette appearance; The development of the buttons is poor, so that the flowering and ramifications are reduced.
Toxicity: Although rare, zinc toxicity occurs when tissue levels exceed 200 ppm. The symptoms are manifested as smaller leaf size, chlorosis in newer leaves, leaves with necrotic tips, delayed plant growth and / or reduced root growth. More often, excess zinc in a substrate competes with phosphorus, iron, manganese or copper to be absorbed by the plant and causes deficiencies of them in the tissue.
Zinc is more readily available for absorption when the substrate has a low pH; So that if this toxicity occurs, it is necessary to measure pH and zinc levels in said substrate. High levels of this element can also be found in some water sources, as well as when it comes into contact with new galvanized metal surfaces. Before analyzing the tissue, rinse the foliage: certain fungicides contain zinc as the active ingredient, which increases the levels of test results.