三種台灣特有種樹苗在不同光環境下的淨光合作用季節變化

Seasonal Variations in Net Photosynthesis of 3 Taiwan Endemic Tree Species Grown under Various Light Environments

郭耀綸(Yau-Lun Kuo) ； 楊月玲(Yeh-Lin Yang) ； 鄭鈞謄(Chun-Teng Cheng) ； 傳瑩娟(Yin-Chuan Fu)

《台灣林業科學》 18卷2期 (2003/06) Pp. 107-116

https://doi.org/10.7075/TJFS.200306.0107

摘要

本研究將3種台灣特有樹種台灣假黃楊、小芽新木薑子及台灣梭羅木的苗木培育在相對光量65、35、10%的蔭棚，以及森林孔隙與林下共5種光環境，分四季測定其淨光合作用及相關生理活動的變化，藉以了解其生理活動對環境因子的反應。各種樹苗隨生長環境光量的提高而有較高的淨光合作用率，但在高溫的季節，培育在35與65%光環境苗木的淨光合作用率常無顯著差異。光合作用生產力以9月最高，12月寒流期間明顯降低，然只有台灣假黃楊的淨光合作用率在不同季節均呈顯著差異。培育在孔隙的苗木當有直射光照時，其淨光合作用率為只有散射光照時的3倍，可達6-9μmo1CO2m^(-2)s^(-1), 然而孔隙苗在只有散射弱光時的光合作用光量子產量極高。在氣溫較高的6、9月，台灣假黃楊和台灣梭羅木的孔隙苗照到直射強光時會出現光合作用光抑制現象，而小芽新木薑子則否，因後者有顯著較高的氣孔傳導率及顯著較低的葉溫。台灣假黃楊、小芽新木薑子及台灣梭羅木孔隙苗光合作用最適溫度範圍分別為23-31℃、23~35℃及18~29℃，顯示小芽新木薑子較耐高溫，台灣梭羅木較耐低溫。

關鍵字

台灣假黃楊 ； 小芽新木薑子 ； 台灣梭羅木 ； 孔隙 ； 光合作用適溫範圍 ； 光抑制 ； 氣孔傳導率

並列摘要

Seedlings of 3 endemic tree species of Taiwan, Liodendron formosanum, Neolitsea parvigemma, and Reevesia formosana, were cultivated under 5 different light environments. They were placed in a forest understory, in a forest gap, and in 3 artificial shade houses with 10, 35, and 65% of full sun, respectively. Seas on al changes of the net photosynthetic rate and related physiological variables of the se seed lings were measured in order to understand their physiological responses to environmental factors. Results showed that as the available light resources increased, the photosynthetic rates in creased accordingly. However, net photosynthetic rates, measured in hot seasons, between seed lings grown under the 35 and 65% light environments showed almost no significant differences. Photosynthetic productivity peaked in September and dropped significantly during a cold period in December. Among these 3 species, only L. formosanum showed significant seasonal variations in net photosynthetic rates. The net photosynthetic rates of seedlings grown in the forest gap were 3-fold higher (6-9 µmol CO2m^(-2)s^(-1) when receiving direct bright light compared to rates when receiving only diffuse, dim light. However, their photosynthetic quantum yields were very high when receiving diffuse, dim light. Photo inhibition occurred in gap seedlings of both L. formosanum and R. formosana when receiving direct bright light in June and September, whereas, gap seedlings of N. parvigemma showed no sign of photoinhibition, which could be attributed to their highs to metal conductance and consequent main tenance of relatively low leaf temperatures. The range of optimum temperatures for photos ynthesis in gap seed lings of L. formosanum, N. parvigemma, and R. for mosana were 23~31℃, 23~35℃, and 18-29℃, respectively. These results indicated that N. parvigemma can to lerant higher temperatures, while R. formosana can tolerant lower temperatures.

並列關鍵字

Liodendron formosanum ； Neolitsea parvigemma ； Reevesia formosana ； gap ； range of optimum temperature for photosynthesis ； photo inhibition ； stomatal conductance