Tailoring red, green, and blue LED spectra to improve yield and quality of Glehnia littoralis.

Selecting the optimal light in Controlled Environment Agriculture (CEA) is crucial for crop yield and quality. However, the optimal light conditions can only be identified through extensive testing. This study proposes a methodology for selecting the optimizing light conditions and applies it to a medicinal herb Glehnia littoralis. Using a mixture design and response surface methodology with red (R), green (G), and blue (B) based LEDs, the optimal light spectrum was identified as R:B = 7:5 based on growth parameters (shoot fresh weight, number of leaves, leaf area, and shoot area). Verification experiments showed that R:B = 7:5 enhanced growth through R and B light synergy, while the high proportion of blue light stimulated secondary metabolism, leading to increased biomass and accumulation of medicinally valuable compounds-imperatorin, bergamottin, and coumarin. These findings highlight the potential of using tailored artificial light spectra in CEA to overcome cultivation challenges and optimize yield and quality, contributing to the development of a stable and sustainable scalable production system for high value medicinal plants.