*4.1. Preparation of Plant Materials*

*S. baicalensis* seeds were purchased from Aram Seed Co. (Seoul, Korea). Seeds for germination were soaked overnight in water. To produce seedlings, 50 seeds were placed in each pot (diameter: 12 cm, height: 11 cm) containing vermiculite and grown in a growth chamber equipped with fluorescent light with a flux rate of 35 <sup>µ</sup>mol·m−<sup>2</sup> ·s <sup>−</sup><sup>1</sup> at 25 ◦C. After 2 weeks, the seedlings in six pots were moved to a room in a growth chamber equipped with each blue, white, and red LED light with a flux rate of 90 <sup>µ</sup>mol·m−<sup>2</sup> ·s <sup>−</sup><sup>1</sup> at 25 ◦C with an 8 h dark/16 h light cycle. The leaves, stems, and roots from seedlings were harvested with liquid nitrogen and then freeze-dried for further metabolite analysis after two and four weeks of LED light treatment. The LED light sources, and their specific information are described in Appendix A Table A1 and a previous study [18]. Seedlings from three pots were used as independent replicates for each LED light for each duration.
