不同光度處理對於咖啡苗木形質與生理反應的影響

Effects of different light on the morphological and physiological responses of Coffea arabica seedlings

本試驗在惠蓀林場，以阿拉比卡咖啡（Coffea arabica）苗木為材料，進行四種不同光度處理，分別為全光（S）、相對光度51.44%（A）、37.51%（B）、8.39%（C）等，觀測光度對於咖啡苗木形質生長與生理反應的影響，可提供作為咖啡種植管理的基礎資訊。形質生長結果顯示低光下C處理的苗木有較佳的生物量，較大的莖根比、葉面積比，而全光下S之苗木，則有較高的根重率、較低的葉面積比。生理反應的結果顯示，低光處理的C苗木有較高的葉綠素含量，較良好的光合作用速率、PSII最大光化學效率（Fv/Fm），以及較低的可溶醣與澱粉比值；而全光處理的S則有較高的可溶醣與澱粉比值、光化學消散（qP），以及較低的光合作用速率。綜合上述結果，建議咖啡苗木的種植過程需要適當的遮陰（至少相對光度50%），才能有良好的表現。 This study used seedlings of Coffea arabica to conduct four different light treatments (8.39 (C), 37.51 (B), 51.44 (A), 100 (S) % of full sunlight) in Hui-Sun Experimental Forest. Effects of light on morphological growth and physiological response were compared to determine the best light environment for growth of Coffea arabica. The morphological growth of seedlings showed the best biomass, stem/root ratio, leaf area ratio under the lowest light (C), on the other hand, the seedlings on the full sunlight (S) had the highest root mass ratio and the lowest leaf area ratio. In tern of physiological response, the seedlings had the highest chlorophyll content, rate of photosynthesis, PS II photochemical efficiency (Fv/Fm), and the lowest ratio of soluble sugar to starch under the lowest light (C), however, the seedlings on the full sunlight (S) had the highest ratio of photosynthesis. According to these result, indicating that Coffea arabica prefer to grow under shade environment.