Light-Emitting Diode Light Quality Influences Germination and Sprout Characteristics of Motherwort

Motherwort (Leonurus japonicus Houtt) is an important medicinal plant known for its excellent antioxidant properties. Nonetheless, in South Korea, its availability remains limited due to the challenge of low seed germination rates, affecting field production. To tackle this problem, it is imperative to focus on controlled production methods. In our study, we conducted experiments in a laboratory setting, employing various combinations of light-emitting diode (LED) lights to cultivate motherwort. The influence of LED light quality on seed germination, initial growth, and functionality of motherwort is evaluated. The germination rate of motherwort ranged from 36.1 ± 7.35% to 75.0 ± 1.60%, and the highest value was observed in the red LED 100% treatment. The mean shoot length also varied depending on LED light quality. The longest shoot length (3.45 ± 0.13 g) was obtained in the red LED 100% treatment. The highest shoot weight (0.266 ± 0.011 cm) and root weight (0.051 ± 0.008 cm) were obtained in the red LED 70% and blue LED 30% mixed treatment. The total phenolic content of the motherwort sprout ranged from 2.50 ± 0.30 mg GAE/g to 3.01 ± 0.09 mg GAE/g, with the highest value from the white LED (control) treatment, but no significant differences were observed among the treatments. The red LED 30% and blue LED 70% mixed treatment showed the highest total flavonoid content (11.62 ± 0.79 mg QE/g) and DPPH radical scavenging activity (57.64 ± 2.95%). The red LED 70% and blue LED 30% mixed treatment had a similar level of DPPH scavenging activity as the control, and there was no positive or negative effect on the functionality of motherwort sprout. Overall, the results suggest that the red LED 70% and blue LED 30% mixed treatment can be effectively used to increase productivity in motherwort without decreasing its important quality.