不同光量及養分對四種臺灣原生闊葉樹苗光合作用及葉綠素螢光反應之影響

Abstract

為瞭解不同林隙條件下適合於復育之樹種參考，本試驗以4種臺灣原生闊葉樹種：三斗石櫟（Pasania ternaticupula (Hayata) Schott.）、青剛櫟（Cyclobalanopsis glauca）、狹葉櫟（Cyclobalanopsis stenophylloides Hayata）與樟樹（Cinnamomum camphora (L.) Presl.）之苗木為對象，進行光量及養分之馴化處理。光量處理分為10%、50%及100% 3種不同相對光量，而養分分為N2、N3、N4、N5及N6等5種養分分級，分別施用氮200、300、400、500、600 kg/ha/yr。試驗自2004年6月至2005年11月在溪頭苗圃進行。實驗期間每月記錄苗木苗高及地徑生長，2005年9~11月進行光合作用及葉綠素螢光之測定。結果顯示：4樹種高生長以相對光量50%下最佳，光量提高使4樹種地徑上升，而較高之養分級對4樹種之高生長及地徑皆有提升的效果。暗呼吸速率、光補償點隨光量上昇而增加。青剛櫟光量子效益在處理間無顯著差異，其餘3樹種在相對光量50%有最高的光量子效益。三斗石櫟與狹葉櫟二樹種最大光合速率以全光下最高，樟樹與青剛櫟以相對光量50%下最高。除三斗石櫟外其餘樹種Fv/Fm於高光量下下降。Fv’/Fm’及ΦPSII在青剛櫟與樟樹二樹種以全光下者最小，相對光量50%表現最佳，狹葉櫟變化不明顯，三斗石櫟則於全光及相對光量50%表現較佳。除青剛櫟外其他3樹種qP值皆隨生長環境的光量之提昇而升高，青剛櫟在相對光量50％時qP高，全光下最小。NPQ除狹葉櫟外其他樹種之NPQ皆隨環境光量提高而升高。養分施用對4樹種光合作用及螢光表現皆無明顯效應。整體顯示，在輕度遮蔭環境下，4樹種皆有良好之高及直徑表現，光合作用表現亦佳，惟青剛櫟與樟樹於強光下顯現光合作用反應中心之抑制，養分施用雖不對生理表現造成影響，對形質生長有一定之助益。

This study was proceeded in the nursery at Chitou from June, 2004 to November, 2005. The objectives were to establish the basic information about the photosynthesis and the chlorophyll fluorescence of four native broad-leaf tree species in Taiwan, which were Nanban tanoak(Pasania ternaticupula (Hayata) Schott.), Ring-cupped oak (Cyclobalanopsis glauca (Thunb. ex Murray)), Arisan oak (Cyclobalanopsis stenophylloides Hayata) and Camphor tree (Cinnamomum camphora (L.) Presl), under different light intensities and nitrogen levels. Treatments of light intensities were measured with relative light intensities which were 10%, 50% and 100%, respectively. Different nitrogen levels were achieved by applying nitrogen fertilizer in the amount of 200 kg/ha/yr(N2), 300 kg/ha/yr(N3), 400 kg/ha/yr(N4), 500 kg/ha/yr(N5) and 600 kg/ha/yr(N6), respectively. We measured the heights and diameters of seedlings monthly throughout the experiment at period. We also measured the photosynthesis and the chlorophyll fluorescence of the seedlings from September to November, 2005. Results showed that all of the four species had the greatest height growth in 50% light intensity and 100% light intensity inhibited the height increasing growth. By contracted diameters increased with light intensity. Higher N levels increased both height and diameters. Dark respiration and light compensation point also increased with light intensities. While the quantum use efficiency of Ring-cupped oak did not differ significantly among treatments, that of the other three species was the high significantly in 50% light intensity than in the other two light intensities(10% and 100%). The maximal assimilation rate of Nanban tanoak and Arisan oak was measured in the full light treatment but that of Camphor tree and Ring-cupped oak was measured in 50% light intensities. Fv/Fm in three of four species, except Nanban Tanoak, decreased in full light intensity. ΦPSII of Ring-cupped oak and camphor tree had the minimal value in full light treatment and maximal value in 50% light intensities. ΦPSII of Arisan oak was little affected by light intensity. Nanban tanoak had better performance in full light and 50% light intensities. The qP of three out of four species, except Ring-cupped oak, increased with light intensities. The qP of Ring-cupped oak had the maximal value in 50% light intensities and the minimal value in the full light. The NPQ of three out of four, except Arisan oak, increased with light intensities. The Nitrogen levels had no significant effects on the photosynthesis and chlorophyll fluorescence of the four species. Ring-cupped oak an Camphor tree showed inhibition of PSII in high light intensities. Nitrogen levels did not influence the physiology of the four species but it would help for height and diameter growth.