Ultra-violet (UV) light is one of abiotic stress factors and causes oxidative stress in plants, but a suitable level of UV radiation can be used to enhance the phytochemical content of plants. The accumulation of antioxidant phenolic compounds in UV-exposed plants may vary depending on the conditions of plant (species, cultivar, age, etc.) and UV (wavelength, energy, irradiation period, etc.). To date, however, little research has been conducted on how leaf thickness affects the pattern of phytochemical accumulation. In this study, we conducted an experiment to find out how the antioxidant phenolic content of kale (Brassica oleracea var. acephala) leaves with different thicknesses react to UV-A light. Kale seedlings were grown in a controlled growth chamber for four weeks under the following conditions: 20°C temperature, 60% relative humidity, 12-hour photoperiod, light source (fluorescent lamp), and photosynthetic photon flux density of 121±10 μmol m-2 s-1. The kale plants were then transferred to two chambers with different CO2 concentrations (382±3.2 and 1,027±11.7 μmol mol-1), and grown for 10 days. After then, each group of kale plants were subjected to UV-A LED (275+285 nm at peak wavelength) light of 25.4 W m-2 for 5 days. As a result, when kale plants with thickened leaves from treatment with high CO2 were exposed to UV-A, they had lower UV sensitivity than thinner leaves. The Fv/Fm (maximum quantum yield on photosystem II) in the leaves of kale exposed to UV-A in a low-concentration CO2 environment decreased abruptly and significantly immediately after UV treatment, but not in kale leaves exposed to UV-A in a high-concentration CO2 environment. The accumulation pattern of total phenolic content, antioxidant capacity and individual phenolic compounds varied according to leaf thickness. In conclusion, this experiment suggests that the UV intensity should vary based on the leaf thickness (age etc.) during UV treatment for phytochemical enhancement.

서 론
재료 및 방법
    1. 식물 재료 및 재배환경
    2. 이산화탄소 처리 및 UV-A 처리
    3. 생육 특성
    4. 광계II 최대 양자수율
    5. 생리활성 화합물 측정
    6. 통계처리
결과 및 고찰
    1. 이산화탄소 처리와 UV-A 조사에 따른 케일의 생육특성
    2. 광계II 최대 광량자 수율(Fv/Fm)의 변화
    3. 총 페놀 함량과 항산화도 및 개별적인 페놀 화합물의변화
결 론
적 요
사 사

• 이진희(전주교육대학교 실과교육과 교수) | Jin-Hui Lee (Professor, Department of Practice Arts Education, Jeonju National University of Education, Jeonju 55101, Korea)
• 오명민(충북대학교 축산·원예·식품공학부 원예학전공 교수, 충북대학교 생물건강산업교육연구단 교수) | Myung-Min Oh (Professor, Division of Animal, Horticultural, and Food Sciences, Chungbuk National University, Cheongju 28644, Korea, Professor, Brain Korea 21 Center for Bio-Health Industry, Chungbuk National University, Cheongju 28644, Korea) Corresponding author