Biomass and Ginsenosides Content of Ginseng Sprouts upon Exposure to Several White LED Lights with Different Correlated Color Temperatures and Color Rendering Indexes

Currently, white light-emitting diode (LED)-based light sources are widely used in vertical farms to improve energy efficient and price competitiveness, and white LED with various light spectra have been produced with the development of phosphor technology. In this study, we discussed the radiation effects of white LED with three different light spectra on the growth and the content of saponin and ginsenosides in ginseng sprouts grown in a vertical farm, specifically assessing the ratios of red, green, and blue light as well as the correlated color temperature (CCT) and color rendering index (CRI). Also, the light use efficiency (LUE) based on growth and the content of saponin and ginsenosides was calculated. For 5 weeks, one-year-old spring ginseng seedlings were cultivated in a vertical farm with three different white LEDs [cool white LED (CW), natural white LED (NW), and warm white LED (WW)]. Fluorescent lamps (FL) were used as a control. The shoot fresh weight, leaf area, stem length, and canopy photosynthetic rate increased as the ratio of red light increased. The total fresh weight was markedly high at WW and was 1.2 times higher than that of the FL treatment. The total saponin and total ginsenosides content were highest in WW and were 1.2 times and 1.3 times higher than those of FL, respectively. In the relationships among the total fresh weight, CCT, and CRI, the total fresh weight was increased with a lower CCT and a higher CRI. The total saponin and total ginsenosides content showed a similar trend according to the white LED light treatments. LUE based on the fresh weight and the content of saponin and ginsenosides were higher under all white LED treatments compared to the FL control group, and the LUE in the WW was 5 times higher based on the shoot fresh weight and 4.5 times higher based on the saponin and ginsenosides content compared to the FL. In conclusion, WW showed the highest performance among the treatments in terms of growth, the saponin and ginsenosides content, and the LUE. Therefore, the cultivation of ginseng sprouts under white LED with a high red light proportion and with a high CRI and low CCT in vertical farms is recommended.