Effects of LED Light Quality on Growth and Physiological Characteristics of Valeriana fauriei in a Smart Farm Environment

Background: Valeriana fauriei is a perennial medicinal plant native to Korea and is valued for its sedative and tranquilizing properties. However, little is known regarding its growth and physiological responses to light quality in controlled environments.<br/>Methods and Results: Seedlings were cultivated for 7 weeks using six LED light treatments [white (W), blue (B), red (R), blue + red (B + R), blue + red + far-red (B + R + FR), and blue + red + white (B + R + W)] under a constant photosynthetic photon flux density (PPFD) of approximately 150 μmol·m⁻²·s⁻¹. Plant height, number of branches, fresh and dry weights, and Soil Plant Analysis Development (SPAD) values were measured. In addition, physiological responses were evaluated using the Normalized Difference Vegetation Index (NDVI), Modified Chlorophyll Absorption in Reflectance Index 1 (MCARI1), Photochemical Reflectance Index (PRI), and Structure-Insensitive Pigment Index (SIPI). Although treatment differences were observed in the mean values, statistical significance was detected only in some biomass-related parameters and the root-to-shoot ratio. Combined light treatments, particularly those including red and blue light with or without far-red light, generally resulted in higher biomass values and more favorable physiological responses than single-spectrum treatments.<br/>Conclusions: Under the conditions of this study, LED light quality exhibited limited statistically significant effects on the growth of V. fauriei; however, certain combined spectra showed consistent trends in growth and physiological responses. These results reveal the potential usefulness of light quality control for smart-farm cultivation of this medicinal plant. However, the results should be interpreted with caution because plant-to-plant variability and a limited sample size may have reduced the statistical power.