光度與養液濃度對女王鹿角蕨生長及光合作用之影響

女王鹿角蕨為大型附生蕨，深具觀賞應用價值，但其幼苗生長緩慢，亟待探討如何加速生長。本研究取具2-3片平展狀營養葉之小苗與具螺旋狀營養葉之中苗，栽培於25/20℃生長箱，以100、200或300μmol．m^(-2)．s^(-1)光量子通量密度（photosynthetic photon flux density，PPFD）搭配每週施用1次0％、25％、50％或100％強生氏營養液處理。結果顯示，未施養液之女王鹿角蕨植株之淨光合作用最低，葉片明顯較小而黃化。於100或200μmol．m^(-2)．s^(-1) PPFD環境搭配施用50％之強生氏營養液即可獲致不錯之生長。具2-3片平展狀營養葉之小苗於300μmol．m^(-2)．s^(-1)PPFD搭配100％強生氏營養液處理者有最高之氣孔導度與淨光合作用值。葉片SPAD-502讀值隨養液濃度提高而增加。在100-300μmol．m^(-2)．s^(-1) PPFD搭配100％強生氏營養液之葉片光補償點介於21.9-35.5μmol．m^(-2)．s^(-1)，其中100μmol．m^(-2)．s^(-1) PPFD處理之暗呼吸速率較低且光補償點較高。於300μmol．m^(-2)．s^(-1) PPFD未施肥之植株葉片有最高之非光化學焠熄係數與最小螢光值與較低之光系統Ⅱ最大光子利用效率F_v/F_m值，其他處理之葉片F_v/F_m介於0.75-0.85。

關鍵字

葉綠素螢光；蕨類；肥培管理；光補償點；氣孔導度

並列摘要

Platycerium wandae Racif. is a large epiphytic fern of great ornamental value. Growers are anxious to reduce the production time by enhancing the slow growth of young plants. Effects of light intensity (100, 200, or 300 μmol．m^(-2)．s^(-1) photosynthetic photon flux density, PPFD) and nutrient solution concentration (0%, 25%, 50%, or 100% Johnson's solution once per week) were studied on growth and photosynthesis of young plants with two sizes, namely with 2-3 sterile fronds or bending sterile fronds grown at 25/20℃. Results showed that plants without fertilization produced the smallest leaf size with the lowest SPAD-502 value and net photosynthetic rate. Plants grew well with 50% Johnson's solution under 100 or 200μmol．m^(-2)．s^(-1) PPFD conditions, whereas maximum leaf size, stomatal conductance, and net photosynthesis were recorded in plants with 2-3 sterile fronds applied with 100% Johnson's solution under 300 μmol．m^(-2)．s^(-1) PPFD conditions. Leaf SPAD-502 value increased with increased nutrient concentration. Light compensation point was estimated between 21.9 and 35.5 μmol．m^(-2)．s^(-1) in plants with 100% Johnson's solution under 100-300 μmol．m^(-2)．s^(-1) PPFD conditions. Plants grown with 100 μmol．m^(-2)．s^(-1) PPFD had the lowest dark respiration rate but the highest light compensation point. Plants under 300 μmol．m^(-2)．s^(-1) PPFD without fertilization had the highest values of non-photochemical quenching (qN) and minimal fluorescence in darkness (F_o) and the lowest quantum efficiency of photosystemⅡphotochemistry (F_v/F_m), while other plants had maximum F_v/F_m of 0.75-0.85.

並列關鍵字

chlorophyll fluorescence ； fern ； fertilization management ； light compensation point ； stomatal conductance

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