Glucosinolate analysis of wild rocket [Diplotaxis tenuifolia (L.) DC] from different Slovenian regions cultivated on two growing systems

Abstract

The present study investigates yield and leaf glucosinolate (GLS) content of 10 wild rocket (Diplotaxis tenuifolia) accessions collected from different regions of Slovenia. Accessions are compared with two commercially available rocket cultivars. Plants were grown in rock wool flakes (soilless floating system) and on peat (conventional system). The yield was significantly higher on the floating system (1,169.6 ± 54.5 g m-2) in comparison with the conventional system (361.6 ± 54.5 g m-2). Leaf extracts were analysed using a high performance liquid chromatography – HPLC system with a diode array detector and peak identification was performed on a mass spectrometer – MS. A significantly higher content of total glucosinolates (GLSs) per dry matter (DM) has been measured on the floating system (7.81 ± 0.59 g kg-1DM) compared to the conventional system (4.91 ± 0.59 g kg-1DM), but the results per fresh matter (FM) did not differ significantly between the two systems analysed. Five GLSs have been identified in wild rocket leaves – glucoraphanin, glucoalyssin, gluconapin, glucosativin and glucoerucin. Glucoraphanin was the most abundant GLS with an average content of 6.85 ± 0.51 g kg-1DM in the soilless and 3.68 ± 0.51 g kg-1DM in the conventional system. No significant differences in total GLSs content have been detected among wild rocket accessions. Two cuts were performed on a soilless system and no significant differences in total GLSs have been determined between the first and second cut. Moreover, no interactions between the sample origin and growing systems have been noted.