四種不同光適應性蕨類植物於光誘導期間之能量消散與光抑制

Energy Quenching and Photoinhibition during Light Induction in Four Fern Species Adapted to Different Light Regimes

Four ferns with different light adaptation capabilities (ranking from high to low, Pyrrosia lingus, Asplenium antiquum, Diplazium donianum, Archangiopteris somai) were used to elucidate energy quenching and photoinhibition during light induction. Pot-grown materials received up to three levels of light intensity, i.e., 100%, 50% and 10% sunlight, according to their light adaptation capabilities. At least six months after light acclimation, plant were illuminated with 50, 100, 300, 500, 1000 and 2000 μmol m –2 s –1 photosynthetic photon flux density (PPFD), respectively, for 30 min, and then dark-adapted for 30 min. Chlorophyll fluorescence were recorded just before and every 2–5 min during illumination and darkness. Results showed that the leaves measured under high-light intensity declined more in PSII efficiency and showed less reversion after dark adapted for 30 min (high photoinhibition). Even though four tested ferns had different capability of light adaptation, when compared to the same level of PPFD, the degree of photoinhibition was only divided into two groups. Among them, P. lingus utilized more sunlight with high photosynthetic capacity, while A. antiquum and D. donianum dissipated more excess light energy through energy-dependent quenching (qE). This showed that three species could maintain a low degree of photoinhibition, and this could possibly be attributed to their adaptation to direct sunlight and sunfleck. In contrast, A. somai,a heavy-shade adapted fern, showed low photosynthetic rate as well as qE, hence they had high level of excess energy and low ability of photoprotection, resulting in high degree of photoinhibition. 本研究以 4 種不同光適應性之蕨類為材料（光適應性由高至低分別為石葦、山蘇花、細柄雙蓋蕨及台灣原始觀音座蓮），探討在光度誘導下，其光保護及光抑制之機制。苗木分別培育於全光、50%遮光及 90%遮光 3 種不同光度環境下 6 個月後，以 50、100、300、500、1,000 及 2,000 μmol m–2 s –1 PPFD 光度各照射 30 分鐘，隨後再暗適應 30 分鐘，於光照前及光照和暗適應過程間每 2-5 分鐘皆紀錄一次葉綠素螢光值。結果顯示，越是陰性物種或於越高光照下測定時，其照光 30 分鐘後之光系統 II 效能（ΦPSIIL30%）之下降程度越大，且在關燈 30 分鐘後之回復程度也越低，表示越容易受到光抑制。光抑制僅可大約分成二群。石葦因其光合作用能力較高可利用較多的光能，而山蘇花及細柄雙蓋蕨則可藉 qE 消散過多的光能，因此這三種受測之物種可維持低光抑制程度。可能這些物種為了適應棲地直射光照或斑光而造成此等特性。相較之下臺灣原始觀音座蓮係重度偏好陰性之物種，其光合作用能力及 qE 皆較弱，光保護能力低下，因而導致光抑制的程度較高。

本研究以 4 種不同光適應性之蕨類為材料（光適應性由高至低分別為石葦、山蘇花、細柄雙蓋蕨及台灣原始觀音座蓮），探討在光度誘導下，其光保護及光抑制之機制。苗木分別培育於全光、50%遮光及 90%遮光 3 種不同光度環境下 6 個月後，以 50、100、300、500、1,000 及 2,000 μmol m–2 s –1 PPFD 光度各照射 30 分鐘，隨後再暗適應 30 分鐘，於光照前及光照和暗適應過程間每 2-5 分鐘皆紀錄一次葉綠素螢光值。結果顯示，越是陰性物種或於越高光照下測定時，其照光 30 分鐘後之光系統 II 效能（ΦPSIIL30%）之下降程度越大，且在關燈 30 分鐘後之回復程度也越低，表示越容易受到光抑制。光抑制僅可大約分成二群。石葦因其光合作用能力較高可利用較多的光能，而山蘇花及細柄雙蓋蕨則可藉 qE 消散過多的光能，因此這三種受測之物種可維持低光抑制程度。可能這些物種為了適應棲地直射光照或斑光而造成此等特性。相較之下臺灣原始觀音座蓮係重度偏好陰性之物種，其光合作用能力及 qE 皆較弱，光保護能力低下，因而導致光抑制的程度較高。