Influence of nitrogen and sulfur fertilization on the mineral composition of broccoli sprouts

Broccoli sprouts (Brassica oleraceae var. italica) have been attributed health protective effects based on their glucosinolate content, and thus, are recommended in diets. However, no information is available on the mineral content of this novel product and how fertilization might influence it. The influence of nitrogen (N) and sulfur (S) applications (0, 14, and 28 mg. N dish(-1) and 0, 4.5, and 9 mg. S dish(-1)) on the mineral content [N, S, potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), chloride (0), and silicon (Si)] of broccoli sprouts (Brassica oleraceae var. italica cv. 'Marathon') was determined 11 d after sowing. It was found that N and S fertilization significantly (P < 0.001) influenced the uptake of all elements except phosphorus (P). Sulfur concentrations in broccoli sprouts varied between 11.4 and 15.2 mg center dot g(-1) (dw), while the Ca, Mg, P, K, and Na concentrations were below 10 mg center dot g(-1) (dw). The Cl contents ranged from 13.6 to 23.1 mg center dot g(-1) (dw). The highest S concentration was found when 9 mg center dot dish(-1) S and 14 mg center dot dish(-1) N was applied. A higher N rates of 28 mg center dot dish(-1), N yielded no higher S uptake. The significantly (P < 0.05) highest Ca, Mg, and Na concentrations were found in the control treatments, while this effect proved to be not consistent for P. The results clearly revealed that N and S fertilization increased biomass production even in the early growth stages. With view to maintaining high Ca concentrations an application in the form of ammonium sulfate would be preferable.