Green leafy Brassica vegetables are rich in nutritionally important constituents including carotenoids. Their content is influenced by pre-harvest factors such as cultivar or agricultural practice. Moreover, carotenoid content correlates with chlorophyll concentration. The aim of the present study was to evaluate the impact of genotype and growing method on lutein and β-carotene contents of Japanese Greens and to establish correlations between carotenoid and chlorophyll contents. Twelve green leafy Brassica cultivars were produced in two different series. For spring production seeds were grown in the greenhouse either in beds or in pots, whereas summer cultivations took place either on open fields or under tunnels. Lutein, β-carotene, chlorophyll a and b contents of Japanese Greens were determined by HPLC–DAD analysis. Overall, lutein concentrations ranged from 3.8 to 10.5 mg/100 g FM and β-carotene contents from 2.1 to 6.8 mg/100 g FM. Botanical classification showed the strongest impact on carotenoid contents with Brassica rapa ssp. chinensis producing significantly more carotenoids than other cultivars. The effect of growing conditions was less pronounced, but slightly higher β-carotene contents were observed in summer. In conclusion, choosing optimal genotypes and to some extent the manipulation of growing conditions offer strategies to increase lutein and β-carotene concentrations.
