鳳梨裂果之發生及減少龜裂之研究

Occurrence of Cracking and Methods to Reduce Fruit Splitting in Pineapple

鳳梨果實的裂果型態可分為裂紋和龜裂，可發生在果目或果目間，以果目間龜裂對果實品質的傷害最大，本研究在探討果實發育過程果實龜裂果發生的時間及評估各種防曬物質對果實外觀保護的效果。夏季果實的果目裂紋常在採收前5週開始深化為果目龜裂，而果目間裂紋的深化為果目間龜裂關鍵時間則稍晚，採收前2週。大體而言，果實上半部果目間龜裂發生率高於下半部、東半部高於西半部的趨勢，但局部性差異未達顯著。在最後一朵小花謝後2週開始使用防曬處理，可有效降低龜裂發生率。無防曬的夏果果目間龜裂發生率高達93%，而慣行的牛皮紙袋防曬措施可以降低果實果目間龜裂發生率36%。複合式防曬處理可更有效率的防護，其發生率介於47-20%。80%的果實無果目間龜裂發生，顯示牛皮紙袋外加鋁箔袋是最佳防曬組合，其生產之果實之可溶性固形物、可滴定酸及糖酸比分別為15.8°Brix、0.68%及23.5，與慣行牛皮紙套袋夏果品質相近，惟酸度偏高，冠芽較小。 Fruit splitting causes severe loss in 'Tainung 17' pineapple fruit production, and the objective of this study was aimed to identifying the occurrence of splitting along the fruit development and evaluate the protection efficiency of a variety of sunscreen materials. The fruit cracked could be divided into cracking and splitting, which could be observed within fruitlet (intrafruitlet) or between fruitlets (interfruitlet). Among the four types, interfruitlet splitting is the most deleterious one. In summer fruit, intrafruitlet cracking often developed into splitting from 5 weeks before harvest, and the critical timing of the interfruitlet splitting was later, 2 weeks before harvest. In general, the splitting occurrence of the upper half fruit was higher than the lower half, the eastern half than the western half, although the difference was not significant. The timing suggested to apply sunscreens was 2 weeks after the anthesis of the last florlet, which could effectively reduce the occurrence of fruit splitting. In summer fruits, 93% of the unprotected fruits observed the interfruitlet splitting, and kraft paper bag, the ordinary sunscreen, reduce the occurrence by 36%. Furthermore, the protection by combining two sunscreens was much more effective with the occurrence ranging from 47 to 20%. Eighty percent of the fruits showing no interfruitlet splitting suggested that wrapping aluminum foil outside the kraft paper bag is the best combination. The total soluble solids, titratable acidity and oBrix/acid was 15.8°Brix、0.68% and 23.5, which was similar to those of kraft paper bagged fruits although the crown was smaller and acidity was higher.