We explored the effects of different light intensities and photoperiods on the growth, nutritional quality and antioxidant properties of two Brassicaceae microgreens (cabbage Brassica oleracea L. and Chinese kale Brassica alboglabra Bailey). There were two experiments: (1) four photosynthetic photon flux densities (PPFD) of 30, 50, 70 or 90 μmoL·m⁻²·s⁻¹ with red:blue:green = 1:1:1 light-emitting diodes (LEDs); (2) five photoperiods of 12, 14, 16, 18 or 20 h·d⁻¹. With the increase of light intensity, the hypocotyl length of cabbage and Chinese kale microgreens shortened. PPFD of 90 μmol·m⁻²·s⁻¹ was beneficial to improve the nutritional quality of cabbage microgreens, which had higher contents of chlorophyll, carotenoids, soluble sugar, soluble protein and vitamin C, as well as increased antioxidant capacity. The optimal PPFD for Chinese kale microgreens was 70 μmol·m⁻²·s⁻¹. Increasing light intensity could increase the antioxidant capacity of cabbage and Chinese kale microgreens, while not significantly affecting glucosinolate (GS) content. The dry and fresh weight of cabbage and Chinese kale microgreens were maximized with a 14-h·d⁻¹ photoperiod. The chlorophyll, carotenoid and soluble protein content in cabbage and Chinese kale microgreens were highest for a 16-h·d⁻¹ photoperiod. The lowest total GS content was found in cabbage microgreens under a 12-h·d⁻¹ photoperiod and in Chinese kale microgreens under 16-h·d⁻¹ photoperiod. In conclusion, the photoperiod of 14~16 h·d⁻¹, and 90 μmol·m⁻²·s⁻¹ and 70 μmol·m⁻²·s⁻¹ PPFD for cabbage and Chinese kale microgreens, respectively, were optimal for cultivation.

The nutritional quality and biomass of various sprouts can be enhanced by Zn and red-blue light, especially the Brassica sprouts. However, the combined effects of this two on sprouts are rarely reported. In this study, different Zn concentrations (0, 1.74, 3.48, 10.43 and 17.39 mM) were combined with two ratios of red-blue light-emitting diodes (LEDs) (R: B = 1:2, 1R2B; R: B = 2:1, 2R1B, at 70 μmol m⁻² s⁻¹ PPFD, 14 h/10 h, light/dark) to investigate their mutual effects on the growth, mineral elements, and nutritional quality in flowering Chinese cabbage sprouts (FCCS). Fresh weight, dry weight, contents of organic Zn, soluble sugar, vitamin C, total flavonoids, total polyphenol, FRAP (ferric ion-reducing antioxidant power) and DPPH (radical inhibition percentage of 1,1-diphenyl-2-picrylhydrazyl) were significantly increased by Zn supplement (10.43 and 17.39 mM) and 2R1B, while hypocotyl length and moisture content were decreased remarkably by Zn supplement. Total glucosinolates contents in the sprouts increased dramatically under 2R1B compared with 1R2B, while photosynthetic pigments contents decreased. Heat map and principal component analysis showed that 2R1B + 17.39 mM Zn was the optimal treatment for the accumulation of biomass and health-promoting compound in FCCS, suggesting that a suitable combination of light quality and Zn supplement might be beneficial to zinc-biofortified FCCS production.