The effects of various intensity of UV-B on barley seedling were investigated by PS I and Ⅱ activities and chlorophyll fluorescence. The inhibitory effect of UV-B radiation on electron transport activity was increased as the intensity of UV-B irradiation was increased. Especially, PS Ⅱ is more sensitive to UV-B radiation than PS I is. By the addition of artificial electron donor, DPC, to the chloroplasts of the barley seedlings treated with UV-B, the photoreduction of DCPIP was recovered by only 11% on electron transport activity. However, the activity of PS Ⅱ was inhibited by 45% by the treatment with UV-B, but recovered it only 11% by the addition of DPC. These suggest that other sites besides the oxidation site of PS Ⅱ may be affected more by UV-B irradiation. As the intensity of UV-B was increased, Fo was increased while Fv was decreased, and thus Fv/Fm was decreased. This means that photochemical efficiency was reduced. With this parameters, it might be that UV-B radiation affected adversely to around PS Ⅱ.

• 박강은(경북대학교 생물교육과) | Kang-Eun Park (Dept. of Biology Education, Kyungpook National University)
• 정화숙(경북대학교 생물교육과) | Hwa-Sook Chung (Dept. of Biology Education, Kyungpook National University)
• 송승달(경북대학교 생물학과) | Seung-Dal Song (Dept. of Biology Kyungpook National University)
• 노광수(계명대학교 생물학과) | Kwang-Soo Roh (Dept. of Biology, Keimyong University)
• 송종석(안동대학교 생물학과) | Jong-Suk Song (Dept. of Biology, Andong National Uiversity)