Calcium is an abundant element in the soil and is absorbed by the plant in its Ca2+ cationic form. It has a structural and functional role in the plant. On the one hand, it is a structural component of cell walls and membranes, ensuring the integrity and functionality of these. It is found in the cell wall in the form of calcium pectate, conferring rigidity to it. In the plasma membrane it acts on its permeability, being able to protect the plant from toxic ions, as well as conditions of high salinity. On the other hand, it plays a functional role as a cofactor of several important enzymes such as α-amylase. Finally, it has a hormonal role, as a secondary messenger in the functioning of some hormones and in physiological responses, playing a fundamental role in cell signaling and plant development.

At an agricultural level it is used especially:

• To avoid the undesirable deficiencies of Ca type BER, Bitter Pitt, Pitt burn and similar, which lead to a high depreciation of the product.
• To confer better shelf-life properties; especially those that refer to a better behavior in transport and withstand several days in suitable conservation conditions.
• To offer greater resistance to the attack of pathogens and to the rupture of cell walls and membranes.
• To offer greater resistance to cracking.

Calcium deficiencies: the lack of calcium is easily recognizable, and it occurs at a greater rate in acidic soils. It is characterized by poor root development and by the appearance of chlorotic zones and necrosis at the edges of younger leaves. Because calcium not a very mobile element and the symptoms mainly affect young tissues and growing areas, it can put a stop to growth. Added to the possible symptoms is the appearance of malformations on the tips of the leaves in the form of a hook, typical characteristic of calcium deficiency and malformation of fruits.