The objective of this study was to investigate the influence that the species, form or cultivar exerts on the glucosinolate spectrum for glucosinolates and free sugars in selected vegetable species of the Brassica genus (Brassica oleracea var. italica Plenck, Brassica rapa var. alboglabra and Brassica oleracea var. botrytis L.). The results showed significant differences amongst the cultivar groups for the glucosinolate proportions as well as the contents of health-promoting and flavour-influencing alkyl, alkenyl and indole glucosinolates. The clear differences in the proportions of glucosinolates amongst the groups were not significantly influenced by the weather, although the absolute glucosinolate contents were. Interestingly, the species, forms and cultivars diverged in their external and internal sensory attributes, for example, colour, taste properties such as bitter and sweet, flavour such as green/ grassy, spicy, broccoli-like, cabbage-like, cauliflower-like, kohlrabi-like, leek-like and mouth-feel pungent. Differences in the sensory attributes led to different consumer acceptability based on first impressions judged on colour, flavour and overall liking. Consumers were seen to prefer cultivars with a bright colour, a lower level of bitter tasting glucosinolates (alkenyl and indole glucosinolates) and a higher sucrose content. Significant correlations were determined between the compound concentrations, the descriptively determined sensory properties and the consumer scores. Here, we identified properties of broccoli and cauliflower which, when optimised to the tastes of the consumer, could boost their acceptability.

The effects of insufficient and optimal sulfur (S) and nitrogen (N) supply on plant growth and glucosinolate formation were studied under controlled experimental conditions in broccoli "Monaco". Here, we report on the interaction between S and N supply, plant growth, and quality parameters and discuss the relevance of this interaction in relation to crop-management strategies. Broccoli plants supplied with insufficient amounts of S or N showed typical deficiency symptoms and yield decreases. In contrast, total glucosinolate concentrations were high at insufficient N supply, independent of the S level, and low at insufficient S supply in combination with an optimal N supply. This was mainly due to the presence of the alkyl glucosinolates glucoraphanin and glucoiberin. Furthermore, with S concentrations above 6 g (kg DM) -1 and an N : S ratio lower than 10:1, the glucosinolate concentrations were on average around 0.33 g (kg fresh matter) -1 and differed significantly from those plants characterized by an S concentration below 6 g (kg DM) -1 and an N : S ratio above 10:1. In addition, N : S ratios between 7:1 and 10:1 promoted plant yield and enhanced overall appearance. Therefore, to produce broccoli (and potentially other Brassicaceae) with higher crop yields and enhanced product quality in the field, it is vital to establish the optimal S and N nutritional status of the plant and to integrate this information into crop-management strategy programs.

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The overall objective of this study was to determine whether growing season, water supply, and their interaction influence glucosinolate (GSL) concentration and composition in turnip roots (Brassica rapa ssp. rapifera L.). Field experiments on a loamy soil in Großbeeren, Germany, were conducted in the spring‐summer (SS), summer‐autumn (SA), and autumn‐winter (AW) growing seasons. Each experiment included three water‐supply treatments with 25%, 50%, and 75% of available soil water (ASW) as lower thresholds. We found that the total GSL concentration in turnip roots was 1774–3221 μmol (kg fresh matter [FM])–1 and the dominant GSL was aromatic gluconasturtiin (GST) with concentrations of 1004–1628 μmol (kg FM)–1 in turnip roots. Total, aliphatic, and some specific individual GSLs in turnip roots were significantly influenced by water supply, growing season, and their interaction, due to the variations of the root sulfur (S) concentration, climatic conditions, or both. The influence of water supply on GSL concentration was modified by growing season, which in turn influenced S concentration in turnips. In the SS season, the 25%‐ASW water treatment enhanced concentrations of total GSLs by 52% and 47%, aliphatic GSLs by 60% and 131%, and aromatic GSLs by 47% and 21% when compared to the 50%‐ and 75%‐ASW water treatments, respectively. No reduction of root yield was observed, although the shoot yield was reduced by limited water supply. In SA and AW, total GSL concentration did not change under different water‐supply levels, but concentration of individual aliphatic and indole GSLs did. Based on these results, growers can adjust their irrigation and S‐fertilization practices to growing season in order to optimize turnip quality in terms of GSL concentration and composition, while still obtaining higher root yield and enabling better resource utilization.