Accumulation of glucosinolates and nutrients in pakchoi (Brassica campestris L. ssp. chinensis var. communis) two cultivar plants exposed to sulfur deficiency

To understand how sulfur nutrition affects the quality and yield of vegetable plants, we have grown two cultivars of pakchoi (Brassica campestris L. ssp. chinensis var. communis cv. Shang Hai Qing and You Dong Er) hydroponically in nutrient solution supplied with two levels of sulfur (0.0558 mM as sulfur deficiency and 1.0058 mM as sulfur sufficiency, respectively) for three weeks and their growth, nutrient uptake and glucosinolate content under these two sulfur conditions were investigated. The results showed that plant growth of both the cultivars was inhibited by sulfur deficiency. The concentrations of nitrogen and magnesium in shoots of both the cultivars were increased notably under sulfur deficiency, but there was no significant change in concentrations of sulfur, potassium and calcium. Moreover, sulfur deficiency increased phosphorus uptake in You Dong Er but not in Shang Hai Qing. In Shang Hai Qing sulfur deficiency reduced the content of all individual and total glucosinolates, while in You Dong Er this was also the case for most individual and total glucosinolates. However, in You Dong Er the total aliphatic glucosinolate concentration was not significantly influenced but the concentrations of individual aliphatic glucosinolates-glucoalyssin and gluconapin were in contrast increased under sulfur deficiency. Our data show that sulfur deficiency will decrease the yield and deteriorate the quality of pakchoi vegetable by reducing its growth and the contents of nutrients and glucosinolates. In addition, there was a significant genotypic variation in the composition and content of glucosinolates between these two pakchoi cultivars when exposed to sulfur deficiency.