Effects of Supplemental Irradiation of UV-A, Blue, and Far-red Light with Red Light on the Growth and Functional Components of Perilla frutescens

Abstract

Green perilla (Perilla frutescens var. crispa) is a highly functional Japanese herb. We investigated the growth of green perilla along with the levels of perillaldehyde, β-carotene, lutein, and rosmarinic acid in the plant when UV-A, blue light, and far-red light were additionally irradiated with red light to confirm the control technology using LED light to produce high-quality green perilla in plant factories efficiently. Twenty-eight-day-old seedlings of green perilla cultivated under white fluorescent lamps were transplanted to a hydroponic culture apparatus. The plants were subjected to different light treatments (red, red and UV-A, red and blue, and red and far-red light) and cultivated for more than 20 days. Perillaldehyde, β-carotene, lutein, and rosmarinic acid contents were quantified using an HPLC system during harvesting. It was observed that top fresh weight, plant height, leaf area attached to the main stem, fresh stem weight, and dry weight of leaves and stems were the highest under red plus far-red light among all light treatments. Addition of blue or far-red to red light did not affect perillaldehyde, lutein, β-carotene, and rosmarinic acid concentrations in green perilla. Irradiation with red plus UV-A light tended to increase the carotenoid concentration and decrease the rosmarinic acid concentration in green perilla, compared with red light only. To cultivate green perilla with high rosmarinic acid concentration, irradiation with only red light is effective, and to cultivate green perilla with high carotenoid concentration, red light supplemented with UV-A is effective.