Growth and phenolic compounds of Lactuca sativa L. grown in a closed-type plant production system with UV-A, -B, or -C lamp

• Published in: Journal of the science of food and agriculture 2014-01, Vol.94 (2), p.197-204
• Main Authors: Lee, Min-Jeong, Son, Jung Eek, Oh, Myung-Min
• Format: Article
• Language: English
• Subjects: Agriculture - methods; Ammonia; Antioxidants; Antioxidants - metabolism; Diet; Food science; Gene Expression; growth; Humans; Lactuca - growth & development; Lactuca - metabolism; Lactuca - radiation effects; Lactuca sativa; Lettuce; phenolics; Phenols; Phenols - metabolism; Phenylalanine Ammonia-Lyase - genetics; Phenylalanine Ammonia-Lyase - metabolism; Phytochemicals; plant factory; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant Leaves - radiation effects; ultraviolet; Ultraviolet radiation; Ultraviolet Rays
• ISSN: 0022-5142; 1097-0010
• DOI: 10.1002/jsfa.6227

BACKGROUND The production of high‐quality crops based on phytochemicals is a strategy for accelerating the practical use of plant factories. Previous studies have demonstrated that ultraviolet (UV) light is effective in improving phytochemical production. This study aimed to determine the effect of various UV wavelengths on growth and phenolic compound accumulation in lettuce (Lactuca sativa L.) grown in a closed‐type plant production system. RESULTS Seven days, 1 day and 0.25 day were determined as the upper limit of the irradiation periods for UV‐A, ‐B, and ‐C, respectively, in the lettuce based on physiological disorders and the fluorescence parameter Fv/Fm. Continuous UV‐A treatment significantly induced the accumulation of phenolic compounds and antioxidants until 4 days of treatment without growth inhibition, consistent with an increase in phenylalanine ammonia lyase (PAL) gene expression and PAL activity. Repeated or gradual UV‐B exposure yielded approximately 1.4–3.6 times more total phenolics and antioxidants, respectively, than the controls did 2 days after the treatments, although both treatments inhibited lettuce growth. Repeated UV‐C exposure increased phenolics but severely inhibited the growth of lettuce plants. CONCLUSION Our data suggest that UV irradiation can improve the accumulation of phenolic compounds with antioxidant properties in lettuce cultivated in plant factories. © 2013 Society of Chemical Industry