不同光度處理對台灣三種原生闊葉樹苗木碳水化合物累積和分配的影響

Effects of Different Light Intensities on Carbohydrate Accumulate and Distribution in Three Native Broad-Leaved Tree Species of Taiwan

本試驗目的在瞭解不同光度下相思樹（Acacia confuse）、烏心石（Michelia formosana）、紅楠（Machilus thunbergii）等3種不同耐陰能力苗木之形質生長、碳水化合物分配及可溶醣組成分析。光度處理係採用相對光度5%、35%與全光（100%），分別將3種苗木以不同光度處理6個月。試驗結果顯示，3種樹種在全光下有最大的相對生長量，其中以相思樹在全光環境下的乾重與相對生長率皆為最高。而生物量分配的部份，可由相思樹莖根比、纖弱指數較鳥心石與紅楠高的結果，得知相思樹傾向於地上部分配較多的生物量，有別於鳥心石與紅楠的生長特性；而Dickson苗木品質指數則顯示在光度較高的環境下，苗木的生長會較平均，較少出現徒長的現象。比葉面積與葉面積比則在低光環境有較大的數值。非結構性碳水化合物的部份，可發現在各種光度下紅楠有最高的可溶醣濃度。可溶醣組成分析顯示，隨著光度的上升，葉部蔗糖的組成比例有較下降的趨勢，而根部蔗糖的比例則呈現增加的現象；至於不同樹種間的差異，發現相思樹和鳥心石的葉部以蔗糖占有比例為最多，而紅楠葉部與根部可溶醣之蔗糖、果糖、葡萄糖比例則較為一致。 This study investigated how light intensities impacted the growth and carbohydrate accumulation and distribution in three native broad-leaved tree species of Taiwan. We set the seedlings of Acacia confuse, Michelia formosana, and Machilus thunbergii on the artificial treatment shaded with different relative light intensities controlled to 5%, 35%, and full light (100%) for six months. Results showed the seedlings had the biggest relative growth rate under full light, especially A. confuse. The morphological features of A. confuse, such as R/T ratio and root weight ratio were lower than M. formosana and M. thunbergii. Specific leaf area and leaf area ratio were decreased with light intensity increased, otherwise the relative height and Dickson quality index were increased with light intensity increased in all seedling, showing uniform seedlings under full light. The non-structural carbohydrate concentrations and pools of M. thunbergii were the highest. In addition, soluble sugar and starch pools of A. confuse decreased with light intensity decreased. The composition of soluble sugar showed that the major composition of A. confuse and M. formosana in leaves was sucrose, and the composition of M. thunbergii in leaves and shoot was almost the same in sucrose, fructose, and glucose.

This study investigated how light intensities impacted the growth and carbohydrate accumulation and distribution in three native broad-leaved tree species of Taiwan. We set the seedlings of Acacia confuse, Michelia formosana, and Machilus thunbergii on the artificial treatment shaded with different relative light intensities controlled to 5%, 35%, and full light (100%) for six months. Results showed the seedlings had the biggest relative growth rate under full light, especially A. confuse. The morphological features of A. confuse, such as R/T ratio and root weight ratio were lower than M. formosana and M. thunbergii. Specific leaf area and leaf area ratio were decreased with light intensity increased, otherwise the relative height and Dickson quality index were increased with light intensity increased in all seedling, showing uniform seedlings under full light. The non-structural carbohydrate concentrations and pools of M. thunbergii were the highest. In addition, soluble sugar and starch pools of A. confuse decreased with light intensity decreased. The composition of soluble sugar showed that the major composition of A. confuse and M. formosana in leaves was sucrose, and the composition of M. thunbergii in leaves and shoot was almost the same in sucrose, fructose, and glucose.