Unveiling the Impact of LED Light on Growing Carrot Taproots: A Novel Hydroponic Cultivation System

Root crops typically develop and enlarge their storage organs in the soil, where they are naturally shielded from light exposure. This characteristic influences their physiological development and presents challenges for hydroponic cultivation, as taproot enlargement is often inhibited when submerged in water. To overcome this limitation, this study introduced a novel hydroponic system that prevents direct submersion in the nutrient solution. By isolating the taproots from both soil and nutrient solution, this system allows precise control of the root-zone light environment using LED irradiation. Carrot taproots were cultivated under blue, green, and red LED light from 42 days after sowing to assess their specific responses to different wavelengths. The results revealed distinct pigment accumulation patterns influenced by light quality. Blue light induced anthocyanin accumulation in the epidermis and outer cortex within 2 days of exposure and also stimulated chlorophyll synthesis in these outer tissues. In contrast, green and red light treatments promoted chlorophyll accumulation primarily in the stele, with red light having the most pronounced effect. These findings suggest that carrot taproots exhibit specific physiological responses to light exposure, demonstrating their ability to adjust pigment biosynthesis depending on the wavelength. By integrating controlled lighting environments into hydroponic systems, this study provides new insights into root development mechanisms and presents a novel strategy for optimizing root crop cultivation.