Effect of LED lights on the antioxidant properties of baby spinach leaves (Spinacia oleracea L. )

The present study employed white (W), blue (B: 468 nm), red (R: 629 nm) and green (G: 524 nm) monochromatic LED lights for 26 days, from 11:00 to 18:00 h (7 h per day), with an average photosynthetic photon flux density (PPFD) of 26.0 m(-2) s(-1) on baby spinach leaves (Spinacia oleracea L), cvs. Falcon F1 and Viroflay, grown in a hydroponic system. Regardless of the cultivar, the fresh and dry weights were positively influenced when the plants were irradiated by R-light in comparison to W-light. Independent of the cultivar, the leaves treated with B-light reached a significantly higher phenolic compound concentration and antioxidant capacity than plants irradiated with W-light. In addition, the green light increased total phenolic compound concentration. According to the results, the use of LED lights is a promising technique for the production of antioxidant compound-enriched leafy vegetables.