여름철 자연조건에서 온주밀감 잎 광계ll의 광억제 = Photoinhibition of PS II in Leaves of Satsuma Mandarin under Summer Natural Conditions

다국어 초록 (Multilingual Abstract)

The street effects of light, temperature and relative humidity in natural conditions were studied on Satsuma mandarin plants(citrus unshiu Marc.) growing in the field during the summer season. ChlorophyII fluorescence induction of leaves was used to characterize the stress effects. Photoinhibition of photosystem II (PS II) was caused in mid-day conditions; ratio of variable to maximum fluorescene (Fv/Fm) decreased
remarkably with increased initial fluorescene (Fo) and decreased maximum fluorescene (Fm). However, it was fully recovered with the onset of night time, indicating that it is not fatal for growth of these plants. Photochemical efficiency of PS II, Fv/Fm, showed significant correlation with light intensity, temperature and relative humidity under natural conditions. Especially, under the supraoptimal conditions (light intensity above
1,000 μmole/m²/sec, temperature above 30.5℃ or relative humidity below 71.2%) in summer, it showed significant correlation with only relative humidity. This results suggest that relative humidity is a limiting factor for photosynthesis of Satsuma mandarin plants under field conditions in summer.