二氧化碳濃度與溫度對樟樹苗木生長及光合作用之影響

Effects of Carbon Dioxide and Temperature on the Growth and Photosynthesis of Cinnamomum camphora Seedlings

許博行(Bor-Hung Sheu) ； 張安瑮(Ann-Li Chang)

《台灣林業科學》 16卷1期 (2001/03) Pp. 11-23

https://doi.org/10.7075/TJFS.200103.0011

摘要

本研究的目的是探討不同CO2濃度及溫度對樟樹苗木生長和光合作用之影響。樟樹苗木生長於開放式玻璃生長箱中，分別施以350±20和700±30ppm CO2濃度以及溫度28/23℃（日／夜）和33/28℃共四種處理。高濃度CO2與高溫處理對於苗木早期淨高生長及淨地際直徑生長皆有促進作用，然10個星期後此促進作用即不明顯，甚至下降。此現象亦有可能因培養盆較小而限制根系之發育。生長於高濃度CO2下，苗木之葉數、總葉面積及乾物量會增加，單葉面積則不受影響。乾物量分配方面，除高溫會降低根／梢比外，其餘各處理間均無顯著差異，CO2濃度與溫度間則無交感作用。將苗木置於同一測定條件下（350或700ppm），生長於高濃度CO2三個月的苗木，其光合作用速率低於生長在大氣CO2濃度者，尤其是生長於高CO2濃度及高溫下的苗木降低更為顯著。在光合作用特性方面，顯示長期高濃度CO2處理將降低苗木的光合作用能力、羧化效益和光捕捉能力，而高溫處理則會加劇高濃度CO2對苗木光合作用的影響。由溫度變化曲線可得知，生長於高溫下之苗木，光合作用最適溫高於常溫處理者，而高濃度CO2處理亦有提高光合作用最適溫的效果。

關鍵字

CO2 ； 溫度 ； 樟樹 ； 生長 ； 光合作用

並列摘要

The effects of carbon dioxide and temperature on the growth and photosynthesis of Cinnamomum camphora seedlings were investigated. Seedlings were cultivated at 2 carbon dioxide concentrations (350±20 and 700±30ppm) and 2 temperatures (28/23℃ and 33/28℃, day/night) in open-top chambers for 3 mo. The net height growth and net diameter growth of seedlings were enhanced in the early period of exposure to high CO2 concentrations and high temperatures. However, when seedlings were exposed for a longer period of time to this high CO2 concentration, net growth of seedlings was inhibited. Seedlings grown in with too small of a volume pots also probably experienced restricted root growth. When seedlings were incubated at the elevated CO2 concentration, the numbers of leaves, total leaf area, and dry matter of seedlings increased. However, individual leaf area was not affected. When seedlings were exposed to higher temperatures, less dry matter was allocated to the roots, so the root/shoot ratio of the seedlings decreased. The photosynthetic rates of seedlings grown in the elevated CO2 concentration for 3 mo were shown to be lower than those of seedlings grown at ambient concentrations when measured under the same conditions (350 or 700ppm). The photosynthetic capacities of seedlings were reduced during long-term elevated CO2 treatment. The carboxylation efficiency and light harvesting ability were also inhibited. The optimum temperature for the photosynthetic rate of seedlings grown at the higher temperature was higher, and seedlings grown in the elevated CO2 concentration also showed an increase in the optimum temperature for photosynthesis.

並列關鍵字

carbon dioxide ； temperature ； Cinnamomum camphora ； growth ； photosynthesis