溫度對不同種源台灣赤楊之光合作用的影響

Effects of Temperature on Photosynthesis of Alnus formosana Provenances

為明暸台灣赤楊能夠從台灣平地至海拔3,000 m 廣泛分布之機制，探討溫度變化對其光合作用之影響。本試驗以三種海拔之台灣赤楊種源及樟樹，測定在短暫低溫（3℃）逆境處理後之光合速率，另以四種海拔之台灣赤楊種源及相思樹在春季及夏季，測定在不同溫度（15~35℃）下之光合速率。結果在短暫低溫（3℃）逆境處理後，比較其光合速率及葉綠素螢光Fv / Fm 之變化，發現兩種測定法所得結果相近，即台灣赤楊三個種源之光合速率及Fv / Fm 之降低比率（約20%）均較樟樹之降低比率（約50%）為低，顯示台灣赤楊對低溫較不敏感。在春、夏二季以不同溫度（15~35℃）下測得之光合速率，發現四個種源之光合作用最適溫度並無明顯差異，即維持80% 以上光合速率之溫度，在台灣赤楊為20~35℃ 左右，相思樹為25~35℃ 間，在15℃ 時，台灣赤楊之光合速率較相思樹高出20% 左右，呈現適溫較廣之特性。綜合上述之結果，可知台灣赤楊為一廣溫型植物。 To understand the mechanism of Taiwan alder (Alnus formosana) that extensively distributes from sea level to 3,000 meters, the study discussed the characteristics of photosynthesis affected by temperatures. Considering the reaction of temperature on photosynthesis, the study measured photosynthetic rates in temporary chilling stress (3℃) for three Taiwan alder provenances and Camphor tree (Cinnamomum camphora). Another measurement was taken at Spring and Summer seasons in different temperatures (15-35 ℃) for four Taiwan alder provenances and Taiwan acacia (Acacia confusa). The results indicated that after giving tested provenances a temporary treatment of chilling stress (3℃), the changes of Fv/Fm for chlorophyll fluorescence and photosynthetic rate were with similar trend. Meanwhile, the decreased photosynthetic rate of Taiwan alder (about 20%) was lower than that of Camphor tree (about 50%). The result revealed that Taiwan alder was less sensitive to low temperature. For Taiwan alder, there were no significant differences of the optimum temperature for photosynthesis among four provenances, the temperature for maintaining over 80% of photosynthetic rate was about 20-35℃. As for Taiwan acacia, the temperature was 25-35℃. When temperature was at 15℃, the photosynthetic rate of Taiwan alder was 20% higher than that of Taiwan acacia. In comparison with Taiwan acacia, Taiwan alder had a wider range of growth temperature. The study concluded that Taiwan alder was a eurythermal plant.

To understand the mechanism of Taiwan alder (Alnus formosana) that extensively distributes from sea level to 3,000 meters, the study discussed the characteristics of photosynthesis affected by temperatures. Considering the reaction of temperature on photosynthesis, the study measured photosynthetic rates in temporary chilling stress (3℃) for three Taiwan alder provenances and Camphor tree (Cinnamomum camphora). Another measurement was taken at Spring and Summer seasons in different temperatures (15-35 ℃) for four Taiwan alder provenances and Taiwan acacia (Acacia confusa). The results indicated that after giving tested provenances a temporary treatment of chilling stress (3℃), the changes of Fv/Fm for chlorophyll fluorescence and photosynthetic rate were with similar trend. Meanwhile, the decreased photosynthetic rate of Taiwan alder (about 20%) was lower than that of Camphor tree (about 50%). The result revealed that Taiwan alder was less sensitive to low temperature. For Taiwan alder, there were no significant differences of the optimum temperature for photosynthesis among four provenances, the temperature for maintaining over 80% of photosynthetic rate was about 20-35℃. As for Taiwan acacia, the temperature was 25-35℃. When temperature was at 15℃, the photosynthetic rate of Taiwan alder was 20% higher than that of Taiwan acacia. In comparison with Taiwan acacia, Taiwan alder had a wider range of growth temperature. The study concluded that Taiwan alder was a eurythermal plant.