To study the effects of calcium‑induced deficiency, tomato plants were grown in three nutrient solutions: one contained the usual calcium concentration (2.5 mM) and the other two solutions to induce deficiency (125 and 62.5 µM Ca²⁺). On these plants, stem height and thickness, leaf humidity, thickness and specific weight, and root fresh and dry weight were determined.
After the adjustment to logistic growth equations, it can be concluded that calcium deficiency slows down stem elongation. In the plants grown in 62.5 µM Ca²⁺ stem growth stops 10‑15 days earlier than in those in 125 µM Ca²⁺. At the end of the growing cycle Ca‑deficient plants compared to controls showed decreases in stem height and thick ness of 50 and 30% respectively.
first visual symptoms of the deficiency appeared on the youngest leaves as a peripheral deformation of the limb. At 62.5 µM Ca²⁺ plant symptoms appeared 7‑10 days after the start of the treatment, whereas for those at 125 µM Ca²⁺, symptoms developed 10‑15 days later. Roots became dark and their size was smaller than those of controls. Plants stopped the development of new tissues, whereas thickness and specific weight increased in the full developed leaves. These effects are similar to those produced by plant growth inhibitors such as paclobutrazol (PBZ), which enhanced leaf thickness and inhibited root development. At the end of the growing cycle, apexes and youngest leaves became necrotic and finally died.