白花蝴蝶蘭由幼年到成熟相之礦物成分和碳水化合物之變化

Changes in Mineral Composition and Carbohydrate Contents from Juvenile to Mature Phase in White-Flowered Phalaenopsis Plants

大白花蝴蝶蘭之實生苗，播種後經2次移植，當最大葉長超出4crn時移出瓶外，種植於威諾型溫室或30／25°C人工氣候室內，出瓶10個月後以日／夜25／20°C生長箱予涼溫催花，探討植株由幼年相轉入過渡期到成熟相之間，其生長、礦物成分與碳水化合物量之變化。結果植株於出瓶後葉面積達100cm2以上時即進入過渡期，出瓶後15～17個月，葉面積達300～500cm2且養分蓄積充實者，即達成熟相，可完全感應涼溫抽梗開花。出瓶後抽梗日數（Y）與植株總葉面積（X）成負相關Y=543.79-0.1939X，成熟植株而未開花者推測係後天環境不當使養分蓄積不足所致。由幼年相轉入過渡期和成熟相中，N和P含量關株齡增加而增加：K、Ca和Mg含量相近，Mn在葉中含量有降低趨勢。葉含K、Ca、Mn比根高出甚多，N和Mg在葉和根含量相近，而P和Fe則根含量較葉片高。葉含高量K、ca、Mg，可能與其為景天酸代謝植物（CAM）之特性有關。葉富含蔗糖（2.69%）和澱粉（5.44%），莖主含蔗糖（3.53%），成熟時濃度略為增加，而根在幼年相和過渡期時主含蔗糖（6.77～10.54%）和葡萄糖（3.93～8.39%），轉入成熟相峙，可溶性醣快速降低，澱粉（1.35～2.08%）呈穩定趨勢，顯示在成熟階段，碳水化合物的分配已發生改變。葉片澱粉含量起伏不定，推測係受栽培環境中光度變化不定所影響。

Seedlings of large white-flowered Phalaenopsis are grown in a Venlo glasshouse or phytotron (30°C day/25°C night)after transplanting out of flask. 10 to 17 months after transplanting, plants are transferred into a growth chamber (25°C day/20°C night) for flower induction and development. The fresh weight, dry weight, leaf area, mineral composition and carbohydrates are analyzed. The results show that plants with total leaf area above 100 cm2 are at transition phase and with total leaf area of 300-500 cm2 /plant, which have high nutrient contents, can 100% induce flowering after cool temperature treatments. Days to flower stalk emerge (Y) is negatively related to total leaf area (X), with the regression equation of Y=543.79-0.1939X. Nitrogen and P contents increase but Mn decreases from juvenile to mature plants. K, Ca and Mn contents in leaves are higher than those in roots. However, P and Fe are higher in roots when compared to leaves. N and Mg contents are similar both in leaves and roots. The major carbohydrate contents are sucrose (2.69%) and starch (5.44%) in leaves, and sucrose (3.53 %) in stems, which increases slightly after transition to mature phase. Root in juvenile plants containes high concentration of sucrose (6.77-10. 54 %) and glucose (3.93-2.08%). However, soluble sugar decreases very quickly and the starch content in root remains almost constant (1.35-2.08%), this result show that the carbohydrate partitioning may have changed after transition to mature phase. Starch content in leaves is highly variable and might be influenced by light intensity under growing conditions.