牛樟扦插苗的生長及光合作用對光量的反應

Growth and Photosynthetic Responses to Light in Rooted Cuttings of Cinnamomum kanehirae

郭耀綸(Yau-Lun Kuo) ； 陳佐治(Tzuoo-Jyh Chen) ； 鄭鈞謄(Chun-Teng Cheng)

《台灣林業科學》 19卷3期 (2004/09) Pp. 215-224

https://doi.org/10.7075/TJFS.200409.0215

摘要

牛樟是台灣特有樹種，經濟價值高。為瞭解其基礎生態生理學性狀供育林作業參考，本研究將牛樟扦插苗培育在相對光量65、35及10%遮蔭設施，以及森林孔隙及林下共五種光環境，測定其生長及光合作用對光量的反應。經22個月的處理，牛樟扦插苗的生物量隨可用光資源提高而增加，但培育在65、35及10%光量者無顯著差異。苗高以培育在10及35%光量者最高，強光抑制苗高生長。牛樟苗生物量分配樣式在不同光環境下具有很大的可塑性。培育在65%光量者分配在根部的生物量高達57%，林下苗反而以分配在莖部的生物量最高，達42%。牛樟苗的生理對高光的馴化能力不強。除了林下苗較低外，其它各處理苗木的光合作用光反應曲線很類似。培育在孔隙及65、35及10%光量四處理苗木的光飽和光合作用率並無顯著差異，均在7.11~8.86μmol m^(-2)s(-1)範圍。培育在35%光量的苗木在一年四季有較高的淨光合作用率，而孔隙苗在6及9月照到直射強光時光合作用率會受抑制。牛樟苗的四季平均淨光合作用率與葉面積的乘值，與各處理苗木的生物量有極顯著直線正相關，顯示上述兩因子可解釋各處理苗木生物量的差異。

關鍵字

生物量分配 ； 生態生理學 ； 光合作用光反應

並列摘要

Cinnamomum kanehirae is a valuable tree species endemic to Taiwan. In order to provide basic ecophysiological information for silviculture practices, rooted cuttings were grown in a forest understory, a forest gap, and in 3 artificial shade houses, which provided 10, 35, and 65% full sun, respectively. Biomass of the cuttings increased as the available light resources increased after 22 mo of treatment. Cuttings experiencing 65% full sun had greater biomass, but did not significantly differ from those grown in 35 and 10% full sun. Cuttings grown in 10 and 35% full sun had the tallest height among all treatments, showing that high light inhibited height growth. Cinnamomum kanehirae showed high plasticity in biomass allocation patterns when grown under different light environments. Cuttings grown in 65% full sun allocated 57% of their total biomass to roots. On the contrary, the understory cuttings allocated 42% biomass to stems. Cuttings of all treatments showed similar patterns of photosynthetic light responses except for the understory cuttings, which had the lowest responses. The light-saturated net photosynthetic rates of the cuttings grown in the gap as well as in the 65, 35, and 10% light environments did not significantly differ, ranging from 7.11 to 8.86μmol m^(-2)s(-1). In situ measurements of photosynthesis in different seasons revealed that cuttings grown in 35% full sun had the highest net photosynthetic rates among all treatments. Photoinhibition occurred in the gap cuttings when receiving direct bright light in June and September There was a significant positive relationship between biomass and the product of seasonal mean net photosynthesis and leaf area of the cuttings, indicating that these 2 factors could explain the variations in biomass of cuttings of this species grown under different light environments.

並列關鍵字

biomass allocation ； ecophysiology ； photosynthetic light response