|Authors: ||T.C. Barickman, D.A. Kopsell, C.E. Sams|
|Keywords: ||glucosinolates, carotenoids, PEITC, and lutein|
Brassica vegetables are commercially recognized for their nutritive values and levels of beneficial phytochemicals that aid in health maintenance and disease prevention.
Watercress (Nasturtium officinal R. Br.) is a leafy vegetable of the Brassicacea family that provides a significant source of carotenoids and glucosinolates (GSs). Lutein, the main carotenoid in watercress, is a lipid-soluble pigment recognized as active in the prevention of cancers and cardiovascular and eye diseases.
Gluconasturtiin, an aromatic GS found in high concentrations in watercress, exhibits both antioxidant and anticarcinogenic activity upon hydrolysis to phenethyl isothiocynate (PEITC). Our research objective was to determine the influence of nitrogen and sulfur fertilization on carotenoid and glucosinolate metabolism in hydroponically grown watercress.
Plants were grown in a factorial arrangement with three nitrogen (N) treatments (6, 56, and 106 mg•L-1) and three sulfur (S) treatments (8, 16, and 32 mg•L-1). Total concentrations of carotenoids and glucosinolates were measured by HPLC analysis.
Nitrogen was positively correlated to lutein concentration which ranged from 2.4 to 9.5 mg•100 g-1 fresh weight (FW); however, S availability did not influence lutein concentrations.
Both (N) and (S) treatments were positively correlated with gluconasturtiin concentrations which ranged from 1.5 to 19.6 µmol•g-1 of dry weight (DW). The impact of (N) and (S) concentration on biomass, chlorophylls, and other individual carotenoids and glucosinolates was determined.
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