Composition and quality of tomato fruit cultivated in nutrient solutions containing different calcium concentrations

Abstract

The effect of different calcium (Ca) doses in the nutrient solution used to cultivate tomato plants on the nutrient and carotene levels of tomato (Lycopersicon esculentum Mill. Cv. Jumbo) fruit was studied. The experiment was conducted in a greenhouse hydroponically using a modified Hoagland solution containing different Ca concentrations (0.2, 2.5, 5.0, 10.0, 15.0, and 20.0 mmol L^‐1). The experiment was conducted in a fully randomized design with three replications. The fruits of the second and third clusters were picked after full ripening and analyzed for their Ca, magnesium (Mg), potassium (K), lycopene, and total carotene levels. Calcium levels in the fruit increased with increasing Ca concentrations in the nutrient solution, reaching a maximum value of 0.17 dag kg^‐1 at a Ca nutrient solution concentration of 19.79 mmol L^‐1. In the 0.2 mmol Ca L^‐1 treatment, the plants died without reaching fructification. The fruits of the plants treated with 2.5 mmol L^‐1 Ca showed blossom‐end rot although this symptom did not occur in the first or second cluster. At this Ca dose, the seeds were small, malformed, and black in color. Magnesium and K levels, however, decreased with increasing Ca concentrations in the nutrient solution, demonstrating the competitive effect of this ion for the sites of absorption and transport in the plant. The total lycopene and carotene levels decreased with increasing Ca concentration in the nutrient solution, possibly due to the reduction in K absorption with minimum levels of 21.50 μg g^‐1 at the Ca concentration of 13.66 mmol L^‐1 in the nutrient solution.