Calcium has a major role in the formation, structure and stability of cell membranes as well as being an important signalling molecule. Through its function as a signalling molecule, calcium is involved in nutrient uptake, the heat stress response and disease mitigation. Calcium deficiency can lead to the deterioration of cell membranes and consequently cell and tissue death. Although calcium is an essential micronutrient, deficiencies are rarely observed in cereals since in most cases the calcium concentration in the soil is sufficient for the demand of the crop.
Calcium has an important role in meristematic growth, and so symptoms of calcium deficiency appear in new growth. Unlike many other micronutrient deficiencies, calcium deficiencies do not lead to chlorosis, and instead the dark green colour is maintained. Necrotic spotting around the middle of the leaf of newest growth occurs, and this spotting expands and the lead then collapses before unrolling. In oilseed rape, deficiency causes stunting of new growth in stems, flowers and roots. Symptoms range from distorted new growth to black spots on leaves. Yellow leaf margins may also appear.