鳳梨裂果之研究

Abstract

‘台農17 號’鳳梨為容易裂果的品種。裂果型態可分為裂紋和龜裂，可發生在苞片、果目或果目間，以果目間龜裂對果實品質的傷害最大，情況嚴重時汁液可能會從裂縫中流出，造成生產者嚴重的損失。因此本研究在探討果實發育過程裂果發生的時間及評估各種防護模式和防護資材對果實外觀的保護效果，建立鳳梨裂果的基本資料。牛皮紙袋套袋之夏季果實，果目龜裂於最後一朵小花謝後3週開始發生，果目間則晚1週；而秋果的果目及果目間龜裂皆於花謝後4週開始發生。龜裂局部性差異有果實上半部顯著高於下半部、東半部略高於西半部的趨勢。 防護處理可降低果目間龜裂發生率，慣行的處理時間為花謝後4週。延後2週開始處理會提高果目間龜裂發生率；提早2週則可有效降低龜裂率，特別是種植小苗且使用複合型防護，果目間龜裂率僅10%。無防護之夏果果目間龜裂發生率高達93%；花謝後2週以慣行的牛皮紙袋套袋可降低36%的發生率；複合型防護處理則可降低46-73%。此外，相較於無任何防護之夏果，防護處理亦可延後果目間龜裂嚴重發生的時間2-4週。在所有處理中，牛皮紙袋外加鋁箔袋為最佳組合，80%的果實無果目間龜裂發生，且果實品質與慣行牛皮紙袋套袋相近，僅酸度偏高及冠芽較小。除防護處理外，夏果以精煉油及噴水處理亦可有效降低果目間龜裂發生率，而塗抹凡士林使發生率增加且果實容易壞疽甚至腐爛，顯示減少但不阻礙果實表面蒸散及維持果實表面的濕潤可減少龜裂發生的機率。整體而言，種植小苗、提早防護處理時間、使用複合型防護及減少果實表面蒸散皆可有效降低果目間龜裂發生，提高可販售果實之比率。

‘Tainung 17’ pineapple is a cultivar that is prone to fruit cracking. The appearance abnormality could be divided into cracking and splitting, which could be observed in bract, within fruitlet (intrafruitlet) or between fruitlets (interfruitlet). Among the six types, interfruitlet splitting is the most deleterious one, and juice might leakage from fissure in severe condition, causing severe loss to fruit producers. Therefore, the objective of this study was aimed to identifying the occurrence of fruit cracking along the fruit development, evaluate the protection efficiency of a variety of sunscreen materials, and establish basic information on fruit cracking of pineapple. The summer fruit of kraft paper bag observed intrafruitlet splitting 3 weeks after the wilting of last florlet, and the critical timing of the interfruitlet splitting was one week later. However, intrafruitlet and interfruitlet splitting often occured while 4 weeks after the wilting of last florlet in autumn fruits. In general, the splitting occurrence of the upper half fruit was higher than the lower half, and the eastern half was higher than the western half. Sunscreens could reduce the occurrence of interfruitlet splitting, and the ordinary time of sunscreens was 4 weeks after the wilting of last florlet. Delaying 2 weeks to apply sunscreens would increase the occurrence of interfruitlet splitting, while 2 weeks earlier could effectively reduce the occurrence, especially in small plants and using combined sunscreen for protection, the occurrence of interfruitlet splitting was only 10%. In summer fruits, 93% of the unprotected fruits observed the interfruitlet splitting, and kraft paper bag, applying sunscreens 2 weeks after the wilting of last florlet, reduce the occurrence by 36%. Furthermore, the protection by combining two sunscreens was much more effective, reduce the occurrence by 46 to 73%. In addition, compared to unprotected fruits of summer fruits, sunscreens also could delay 2-4 weeks of the critical time of interfruitlet splitting occurred. Among all the sunscreen treatments, wrapping aluminum foil outside the kraft paper bag is the best combination, 80% of fruits showing no interfruitlet splitting. Furthermore, fruit quality was similar to kraft paper bagged fruits, although the acidity was higher and crown was smaller. In addition to the sunscreen treatments, we could also reduce the occurrence of interfruitlet splitting by spraying the petroleum oil and water in summer fruits. However, the occurrence of Vaseline treatment was increased, and the fruits was prone to necrosis or enen rot. The result showed that reducing but not hindering fruit transpiration or maintaining the moisure of fruit surface could reduce fruit splitting. Overall, planting small slips, applying sunscreens earlier, using combined sunscreen treatment, and reducing transpiration of fruit surface all could effectively reduce the occurrence of interfruitlet splitting and increase the fruit value.