Effect of different sulfur fertilizer doses on the glucosinolate content and profile of white mustard seeds

After nitrogen, phosphorus and potassium, sulfur is another essential element that is required for the optimal growth, development and yield of white mustard and other species of the family Brassicaceae. The effect of different pre-sowing sulfur fertilizer doses on the glucosinolate content and profile of three traditional white mustard cultivars that are widely grown in Poland was analyzed in a three-year, small-area field experiment. White mustard was grown in the experimental fields of the Wrocław University of Environmental and Life Sciences in south-western Poland in 2007-2009. The experiment had a split-plot design with two levels of experimental factors. White mustard cultivar (Metex, Nakielska, Radena) was the first experimental factor, and sulfur fertilizer dose (0, 10, 20, 30 S kg ha-1) was the second experimental factor. The glucosinolate content of white mustard seeds was analyzed by gas chromatography. White mustard seeds were most abundant in sinalbin, an aromatic glucosinolate. The sinalbin content of seeds varied in response to different sulfur fertilizer doses. An increase in the sinalbin concentration was observed already in response to a sulfur dose of 10 kg ha-1 relative to the control treatment. The total content of aliphatic glucosinolates was significantly lowest in the treatment where sulfur fertilization was not applied. The content of aliphatic glucosinolates in white mustard seeds was significantly highest in the treatment fertilized with sulfur at 20 kg ha-1. Weather conditions significantly influenced the total glucosinolate content and the proportions of the analyzed glucosinolate groups in white mustard seeds.