Interactive effects of genotype and N/S-supply on glucosinolates and glucosinolate breakdown products in Chinese cabbage (<i>Brassica rapa</i> L. ssp. <i>pekinensis</i>)

Abstract

Chinese cabbage is rich in glucosinolates (GLS) and their breakdown products, mainly isothiocyanates (ITC), which are assumed to be human health-promoting compounds. Sulphur and nitrogen have been shown to influence concentrations and patterns of both. Little is known as to whether the effect of varying sulphur and nitrogen nutrition on glucosinolate and isothiocyanate content is influenced by the genotype. Therefore, two cultivars of Brassica rapa L. ssp. pekinensis were grown with increasing S (0.0, 0.3, and 0.6 g pot-1) and N (1 and 2 g pot-1) supply. Results show that total GLS concentration increased with higher N and S application, but ratios between individual GLS compounds remained unchanged. High N supply reduced the concentration of GLS, especially of the aliphatic ones, while the indole and aromatic GLS exhibited statistically insignificant responses to increasing N and S application. The profile of breakdown products was dominated by epithionitriles, followed by ITCs and nitriles. The ITCs were substantially reduced in response to increasing N and decreasing S supply. This was not observed for nitriles. Overall, GLS pattern were primarily influenced by the genetic background of the cultivar and less influenced by differential nutrition. Results show that selection of the cultivar is of utmost importance when glucosinolates and their breakdown products shall be increased by fertilization. The online version of this article (doi: 10.5073/JABFQ.2016.089.036) contains supplementary files.

Keywords

• Brassica rapa L. ssp. pekinensis
• glucosinolates
• isothiocyanates
• breakdown products
• nitrile