Mineral Nutrient Density of Cabbage 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 cabbage (Brassica oleracea var. capitata) can be increased through selection of cultivars and nutritional regimes. Nineteen cultivars of cabbage 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 cabbage heads were determined by plasma spectrophotometry. The organic fertility regime resulted in higher yield (fresh or dry weight) than compost, but lesser yield than chemical fertility regime. Chemical and organic fertility regimes resulted in about 12% higher Mg, 17% higher Cu, and 9% higher Zn than compost fertilization with lower but significant differences occurring among most of the other elements. Differences among individual cultivars for each element were large with some cultivars having nearly three times the concentrations of nutrients of others and with considerable uniformity in cultivar rankings among the elements. This work suggests that cultivars and nutritional regimes can be selected for production of nutrient-dense cabbage.