Evolution of Nutritional Value of Two Tomato Genotypes Grown in Soilless Culture as Affected by Macrocation Proportions

A greenhouse experiment was carried out to determine the effect of cationic proportions (K, Ca, Mg) in the nutrient solution on carotenoids and α-tocopherol content at green-orange, orange, red, and intense-red ripening stages using a high-pigment tomato (Lycopersicon esculentum Mill.) cultivar hp ('Lunarossa') and a standard cultivar ('Corfu') grown in a soilless culture. The highest lycopene concentration was observed in the 'hp' cultivar at the red and intense-red ripening stages (3.0 mg/100 g fresh weight and 3.2 mg/100 g fresh weight respectively). In both cultivars, the concentration of β-carotene increased during the ripening stages, reaching the highest value (0.6 mg/100 g fresh weight) at the intense-red stage. The hp cultivar has guaranteed higher lycopene (average, 2.0 mg/100 g fresh weight vs. 1.7 mg/100 g fresh weight) and α-tocopherol contents (average, 1.2 mg/100 g fresh weight vs. 0.9 mg/100 g fresh weight) than those of the standard. In both cultivars, a high proportion of K in the nutrient solution increased antioxidant concentration (β-carotene and especially lycopene) during the red and intense-red ripening stages, followed by Mg. The lowest values were recorded for the Ca treatment. Lastly, a positive correlation was recorded between fruit tissue K and lycopene content, whereas a negative correlation was observed between fruit tissue Ca and lycopene content.