Evaluation of Growth, Vegetation Indices, and Photosynthesis of Cichorium intybus L. Seedlings as Affected by LED Light Qualities in a Closed Nursery Facility

Cichorium intybus, a leafy vegetable belonging to the Asteraceae family, is known for its potential health benefits and the inclusion of various bioactive compounds and indigestible oligosaccharides that improve liver function and aid in fatigue recovery. In this study, we evaluated the effects of light-emitting diode (LED) light qualities on the growth, vegetation indices, and photosynthesis of the C. intybus cultivars 'Asia Sugar' and 'Rossa Italiana', grown in a closed nursery facility. LED light treatments included seven types of monochromatic, composite, and white LEDs (i.e., red, green, blue; purple; 3000, 4100, and 6500 K white LEDs) applied to these cultivars. The results showed that 'Asia Sugar' reached its largest size under the 3000 and 4100 K white LED treatments, whereas 'Rossa Italiana' exhibited the highest growth under the 3000 K white LED light treatment. An analysis of monochromatic light revealed that red LED light increased plant sizes and weights compared to blue LED light, and a higher distribution of red wavelengths within the white light spectrum positively influenced plant sizes and weights. With regard to increasing plant weights, both cultivars performed best under 3000 and 4100 K white LEDs, similar to the results for plant sizes. In contrast, 'Asia Sugar' showed the most favorable vegetation and photosynthetic indices under 4100 and 6500 K white LEDs, while the 'Rossa Italiana' showed the most favorable photosynthetic indices and chlorophyll content (SPAD units) under 6500 K white LED, opposite to the plant size results. These findings provide valuable insights into how specific LED light qualities can be optimized to enhance the growth and physiological responses of Cichorium intybus cultivars seedlings.