The effects of LED illumination spectra and intensity on carotenoid content in Brassicaceae microgreens

The objective of this study was to evaluate the effects of irradiance levels and spectra produced by solid-state light-emitting diodes (LEDs) on carotenoid content and composition changes in Brassicaceae microgreens. A system of five high-power, solid-state lighting modules with standard 447-, 638-, 665-, and 731-nm LEDs was used in the experiments. Two experiments were performed: (1) evaluation of LED irradiance levels of 545, 440, 330, 220, and 110 μmol m−2 s−1 photosynthetically active flux density (PPFD) and (2) evaluation of the effects of 520-, 595-, and 622-nm LEDs supplemental to the standard set of LEDs. Concentrations of various carotenoids in red pak choi and tatsoi were higher under illumination of 330-440 μmol m−2 s−1 and at 110-220 μmol m−2 s−1 in mustard. All supplemental wavelengths increased total carotenoid content in mustard but decreased it in red pak choi. Carotenoid content increased in tatsoi under supplemental yellow light.