紫外線對茶樹嫩梢兒茶素含量與葉片細胞膜熱穩定性之影響

Effect of Ultraviolet Radiation on Catechins Content and Leaf Cell Membrane Heat Stability of Tea

本研究以紫外線照射茶樹，以了解其對茶樹嫩梢兒茶素含量與葉肉細胞細胞膜熱 穩定性之影響。移植後一年生‘臺茶十二號’與‘青心烏龍’茶苗，置於溫控生長箱中，以 UVA 與 UV-B 處理一天與五天，以及以 UV-A 處理一週與兩週。試驗結果顯示，短時間施予紫 外線，會改變茶葉嫩梢中兒茶素含量。以 UV-A 處理一天後，‘臺茶十二號’與‘青心烏龍’嫩 梢之兒茶素中 epicatechin （EC）之含量均增加，其他兒茶素含量變化趨勢並非完全一致。在 UV-B 處理下，除處理一天後‘青心烏龍’ 茶葉嫩梢中 epicatechin （EC）之含量顯著增加外，無 論處理時間長短，以 UV-B 處理兩品種茶樹，其嫩梢中兒茶素含量均有減少趨勢。以 UV-A 長期處理，即處理一周與兩周下，‘青心烏龍’處理低劑量（0.56 mWcm-2 ）者，葉片中中兒茶 素含量會明顯增加，但處理高劑量者（0.93 mWcm-2 ）葉片內兒茶素含量雖高於對照，但差異 不顯著，處理時間長短，並不影響葉片中兒茶素含量。青心烏龍茶台茶 12 號茶菁的第二片 葉之葉肉，在未經日光照射下，放置 120 分鐘，膜的穩定性才明顯下降，但在紫外線處理 20 分鐘後，以 UV-A 及 UV-C 處理者，細胞膜穩定性即開始明顯下降。如剔除偏離值，則 處理 20 分鐘後，紫外線處理即顯著影響膜之穩定性，除 UV-B 處理者之外，均與對照差異 顯著，處理 30 分鐘，則 UV 處理者膜穩定性均顯著低於對照。

'TTES No. 12'' and ''Chin Hsin Oolong'' potted plants, which were transplanted after one year, was treated with ultraviolet rays to investigate the changes of catechins content and leaf cell membrane heat stability (LCMHS), in growth chamber. After treated UV-A for one day epicatechin (EC) content was increased in both two cultivars, while only ''Chin Hsin Oolong'' increased under UV-B treatment. Except One-day-treatment ''Chin Hsin Oolong''plant, UV-B treatment reduced total catechin content of leaves, while total catechin content of leaves of ''Chin Hsin Oolong'' was significantly increased under low dosage UV-A treatment and was no-significantly increased of other treatments. Leave LCMHS were significantly reduced after 120 min. under dark condition, but were significantly decreased after 20min. UV-A and UV-B treatment.