Fig. 5

Effects of light quality and intensity on melatonin concentration in H. perforatum L. a level F (approximately 90 µmol·m²/s photons), b level 5 (approximately 45 µmol·m²/s photons), and c level 1 (approximately 9 µmol·m²/s photons). The eight LED light sources are indicated as CW (cool white light, 5000 K), WW (warm white light, 2700 K), 9B (450 nm), 9R (660 nm), 7R1G1B (R:G:B:IR ratio = 82:9:9:0), 8R1B (R:G:B:IR ratio = 91:0:9:0), 3R3B3FR (R:G:B:IR ratio = 49:1:33:17), and 9FR (730 nm). Data are the mean of three replicates, and different letters represent significant differences at p < 0.05