塔塔加地區臺灣雲杉(Picea morrisonicola)光合作用之季節變化

Abstract

本研究之目的在探討生長於亞熱帶亞高山地區臺灣雲杉(Picea morrisonicola)光合作用能力之季節變化，試驗於1998年11月至2001年5月間進行。結果顯示光合作用能力(光飽合淨光合速率，psat)、葉綠素螢光(Fv/Fm)及可溶性蛋白質(SP)含量等在仲或暮春經夏秋至早冬期間均維持在較高之水準。其中Fv/Fm值大致與氣溫間呈曲線迴歸關係，Fv/Fm開始降低或完全恢復之關鍵日均溫約在12℃左右Psat及SP之季節變化與Fv/Fm的變化趨勢大致相似，但入春後氣溫及Fv/Fm均已回升，但Psat及SP含量仍暫處於較低之水準。複迥歸分析結果顯示Fv/Fm與SP含量共同影響了Psat的季節變化，其迴歸方程式為：Psat=-3594+6288 Fv/Fm+22.21SP，(R2=0.788，p<0.01)。顯示臺灣雲杉在冬季Psat降低及在春季回復之主因，為光抑制及葉片可溶性蛋白質含量之變化所致。而Psat在春季回復遲緩之原因，為葉片可溶性蛋白質含量回升較慢使然。 The purpose of this study is to investigate seasonal variation in photosynthesis capacity of Taiwan spruce (Picea morrisonicola) grown in sub-alpine region (Tatachia area, 23°29', 120°53', 2650 m) of Taiwan. Experiments were conducted from November 1998 to May 2001 to cover several different growing seasons. It was observed that the photosynthesis capacity (light saturated net photosynthetic rate, Psat), chlorophyll fluorescence (Fv/Fm) and soluble protein (SP) content of needles maintained in higher levels during the period from mid or late spring to early winter. A curvilinear relationship was detected between Fv/Fm and multi-day mean temperature. Among these independent variables, the mean temperature of the measuring days showed the highest correlation to the Fv/Fm. The switching point for Fv/Fm activities, either start to decrease or begin to make full recovery, was found at about 12℃ air temperature. The seasonal variations of Psat and soluble protein content of needles were similar to that of the Fv/Fm. However, at early or mid spring, Psat and soluble protein content were still kept in a lower level, whereas the air temperature and Fv/Fm levels had already risen. By applying multiple regression analysis, it was shown that both Fv/Fm and soluble protein content of needles affected the seasonal variation of Psat: Psat -359.04+623.88 Fv/Fm + 22.21 sp, (R2=0.788, P<0.01). Results suggest that the decrease in photosynthesis capacity for Taiwan spruce in winter and its recovery in the spring may due to the photoinhibition and soluble protein content in needles. The other possible reason of the delay in the recovery for photosynthesis capacity in spring may due to the late recovery of soluble protein contents in needles.