摘要
紅龍果 (Hylocereus spp.) 為仙人掌科 (Cactaceae) 多年生作物，屬典型長日植物，臨界日長約為12小時，正期果產期落在6-12月初。近年來因市場過度飽和正期果價格下跌。雙色品系，紅色外緣果肉 (果緣) 包覆白色中央果肉 (果心) ，成為新興品系，但雙色呈色不穩定。探討雙色呈色不穩定的因素成為重要議題。藉由果肉全年物候，包含呈色、總可溶性固形物 (total soluble solids, TSS) 、可滴定酸 (titratable acid, TA) 含量變化等。此外，本論文也紀錄果實發育與轉色過程，並分析GA3、CPPU、H2O2、花粉直感和套袋對紅龍果雙色呈色的影響。 雙色紅龍果果實轉色是由內果皮開始產生甜菜紅色素，隨後中果皮和外果皮也開始累積色素而達成果皮轉紅，夏季和冬季的外果皮轉色時間，分別為花後26-28及42-47天，果皮轉色後一週內，甜菜紅色素擴及果肉，依序可滲透至果緣及果心部位。雙色呈色分布可能與果心及果緣的TSS含量有關，TSS含量越高、果肉顏色越白；因此果實的雙色特徵與果肉TSS含量分布有關。果心為果實TSS含量最高的部位，呈色偏白，果緣為TSS含量低的部位，呈色偏紅。將果實剖面照片，依果心 (X軸) 及果緣 (Y軸) 的TSS排列，可看出雙色呈色較佳的果實TSS含量座標約為 (11.5-13oBrix，19-20oBrix) 。果緣部位TSS含量越低，紅色呈色越深且越寬；同理，果心部位也會因為TSS含量過低而無法維持白色。從栽培管理上控制果實TSS含量，穩定果實的雙色特徵是可行的。 由於栽培環境及模式的差異，花蓮果園較屏東果園正期果雙色呈色穩定。屏東果園7-9月的果實，整體果肉TSS含量較高，果緣部位的顏色非常淡，整體果實偏白；10月以後到正期果產期結束，果實呈現雙色特徵因為果肉TSS含量降至雙色呈色範圍。產期調節果實多趨近紅肉果，因為整體果肉TSS含量低於雙色呈色範圍。GA3、CPPU、H2O2、花粉直感和套袋皆未顯著影響紅龍果雙色呈色，但當開花當天外施的GA3濃度增加，果緣的紅色有漸淡趨勢，但不甚明顯。
並列摘要
Pitaya (Hylocereus spp.), a perennial crop of Cactaceae, is a typical long-day plant with critical day length of 12 hours, in that the fruit is harvested from June to early December. In recent years, the price of in-season fruits dropped dramatically due to over production. As the result, the bicolored pitaya, showing white central pulp surrounded by red pulp, became a new star variety for the unique pigmentation; however, the standard bicolor pattern is not stable. Reasons causing the un-stability become an urgent issue. We first investigated the annual pigmentation phenology of pulp including color pattern, total soluble solids (TSS) and titratable acid (TA) content. We also documented the fruit development along with color transition process. The effect of bagging, GA3, CPPU, H2O2, pollen intuition, and fertilization on bicolor pattern were also evaluated. The pigmentation of peel was from the inner layer of endocarp towards outer layer, and finally the entire peel turned red. The timing was approximately 26-28 and 42-47 days after anthesis in summer and winter, respectively. The pulp coloring started from the surrounding area near the endocarp and penetrated inward within one week after the peel fully turned red. The pulp bicolor was highly affected by pulp total soluble solids. The higher pulp TSS content was, the whiter the pulp color was. Therefore, the bicolor phenotype was related with the pulp TSS distribution. The central pulp, highest TSS content portion, tended to be white; and the surrounding pulp, tended to be red. Display the photos of the fruit longitudinal section to the 2D panel according the TSS content of the central pulp (X-axis) and surrounding pulp (Y-axis), the bicolor fruits loaded around (11.5-13oBrix, 19-20oBrix). The red color portion of the surrounding pulp was getting to be deeper and wider along with its decrease in TSS content. The white color of central pulp could not maintain as the TSS content gets too low. Therefore, maintaining fruit TSS to be in certain range through cultural practice, stabilization of the bicolor phenotype could be possible. Due to the differences in cultural practice and location, the bicolor phenotype was more stable in the fruits produced in Hualien than Pingtung. In Pingtung, the TSS content of the fruits produced from July to September in pulp was too high, the color of the surrounding pulp was very light or white which resulted in white color fruit, while fruits produced from October to the end of the production season showed bicolor phenotype because the TSS content of pulp was decreased to the bicolor range. The fruits of off-season production were more closed to red pulp for their TSS contents of pulp were much lower than the bicolor range. The effect of bagging, GA3, CPPU, H2O2, pollen intuition, and fertilization on bicolor pattern were not obvious, even though fruits that applied higher concentration of GA3 at the anthesis day showed lighter pigmentation.