Mineral Nutrient Density of Tomato in Response to Cultivar Selection and Nutritional Regimes

Mineral nutrient deficiency in vegetable-based foods is a substantial concern in human diets. Depleted soil fertility and high-yielding cultivars have been associated with low nutrient contents in vegetables. Research is needed to develop systems that introduce nutrient-dense crops to the markets. This study explored if mineral nutrient densities of tomato (Lycopersicon esculentum Mill.) can be increased through selection of cultivars and nutritional regimes. Twenty-four cultivars with different phenotypes of heritage and modern origins were studied in field experiments. Conventional fertilizer (10–10–10), compost, and an organic fertility regime of soybean meal, bone meal, and potassium sulfate were assessed.  Compost was applied at 40 Mg/ha, and chemical or organic fertilizers provided 75 kg N–75 kg P₂O₅–75 kg K₂O/ha. Elements in tomato fruits were determined by plasma spectrophotometry. Modern cultivars had about 12% higher Ca and about 21% lower Fe concentrations than heritage cultivars with no differences occurring for most of the other elements. Chemical and organic fertility regimes resulted in about 13% higher K and 29% higher Ca than compost fertilization with no differences occurring among most of the other elements. Differences among individual cultivars for each element were large with some cultivars having nearly twice the concentrations of nutrients of others and with considerable uniformity in cultivar rankings among the elements. No interactions occurred between nutritional regimes and cultivars or genotypes. This work suggests that cultivars and nutritional regimes can be selected for production of nutrient-dense tomatoes.