Abstract
Japanese honeysuckle is an evergreen vine that grows naturally in Japan and East Asia. The buds and leaves of this plant are used as crude drugs known as Kinginka and Nindou, respectively, in Japan and East Asia. The medicinal compounds are chlorogenic acid and luteolin, which have antiviral, anticancer, anti-inflammatory, and antioxidant activities. The optimal environmental conditions for growing Japanese honeysuckle have remained unknown thus far. The aim of this study was to investigate the effects of supplemental lighting in winter greenhouse on growth and production of medicinal compounds in Japanese honeysuckle. For that purpose, we cultivated Japanese honeysuckle plants in a greenhouse using supplemental lighting from high-pressure sodium lamps. During the experiment, the daily light integral was maintained at 10 mol m −2 d −1 by controlling the irradiation period of supplemental lighting from the evening until midnight. The total dry weight and total leaf area of plants subjected to 55 d of supplemental lighting were significantly higher than those in control plants. The number of flower buds was significantly higher in treated plants, and then, there was no difference in the concentration of chlorogenic acid and luteolin between the two groups. In conclusion, supplemental lighting is a useful method for winter cultivation of Japanese honeysuckle that increases the yield of flower buds and does not decrease the concentration of main medicinal compounds.
