Which symptom would indicate a calcium deficiency in plants?

A symptom indicating a calcium deficiency in plants is stunted or deformed new leaves. Calcium plays a crucial role in plant health, primarily by contributing to the structure and stability of cell walls. When there is a lack of calcium, newly developing leaves may exhibit malformations such as curling or distortion, and they may also be smaller than normal. This is particularly evident in the youngest leaves because calcium is not mobile within the plant, meaning it remains in the areas where it was absorbed. As a result, new growth suffers first from a calcium deficiency, confirming that stunted or deformed new leaves are a direct consequence of insufficient calcium availability.

In contrast, the other symptoms listed, such as yellow leaves with green veins, old leaves turning dark, and new leaves with irregular lesions, are associated with deficiencies of other nutrients, like nitrogen, magnesium, and potassium, rather than calcium specifically. Thus, understanding these plant symptoms can help pinpoint nutrient deficiencies accurately, which is essential for effective plant care and management.