氮肥施用量對鳳梨果實內部褐化及水浸狀生理障礙之影響

Abstract

臺灣的鳳梨品質易受季節性的變動而改變，其中果皮轉色速率、果心及果肉褐化與果肉水浸狀現象為其中之最。本試驗擬探討於催花後施用尿素對春、夏採收鳳梨果實品質之影響。果皮轉色、果心與果肉褐化、水浸狀、果實可溶性固形物、可滴定酸含量為本研究之主要調查項目。此外，儲藏對果實品質之影響也為本試驗之評估項目。 於催花後施用尿素時，會使春果的果皮轉色時機延後，果肉水浸狀的發生率及嚴重度略微增加，但不影響果實聲響、重量、體積、比重及冠芽重；雖然糖酸比變動不大，但果實可溶性固形物及可滴定酸則略微減少。採收時果皮顏色的轉黃程度高時，果肉水浸狀的發生率及嚴重度會提高，可滴定酸下降，而可溶性固形物含量則會提高。剛轉黃與半黃轉色採收之春果，於室溫下儲藏至果皮全部轉黃時，分別需要10及14天，儲藏前後除了儲藏後均產生果心褐化現象，其他果實品質變動不大，此褐化現象之嚴重度且隨尿素增施而提高。半黃至全黃轉色採收之春果儲藏後，果心褐化現象嚴重並出現輕微的果肉褐化及水浸狀顯現，其嚴重度有隨尿素增施而增加之趨勢。 於催花後施用尿素時，也會使夏果的果皮轉黃的時機延後，果肉水浸狀的發生率及嚴重度均隨尿素增施而大幅提高，柱聲果及肉聲果發生率增加，果實之果重、體積及比重均提高，冠芽重則不受影響，可溶性固形物及可滴定酸減少，糖酸比則提升。採收時果皮顏色的轉黃程度對夏果果實品質的影響與春果類似，除其可溶性固性物的含量不受影響。半黃至全黃轉色採收之夏果，易顯現輕微的果心褐化及高度的果肉水浸狀現象，隨尿素施用量增加，果心褐化的發生率及嚴重度略微減低，但果肉水浸狀的發生率及嚴重度均大幅提高。 總而言之，春果於半黃至全黃轉色時採收，而夏果於剛轉黃時採收，其品質較佳。經室溫或冷藏儲運後，春果易產生嚴重的果心褐化，夏果則易顯現高度的果肉水浸狀現象，而催花後施尿素則會加重這些劣變現象。

The fruit qualities of pineapple are affected by the production season in Taiwan, particularly the peel color turning, the flesh and core browning and flesh translucency . The objective of the thesis was to evaluate the effect of urea application after forcing on the qualities of the spring and summer fruits. The peel coloring turning, flesh and core browning and translucency, fruit total soluble sugar and titratable acidity have been investigated. Besides, the effect of storage on those qualities was also evaluated. For spring fruits, the urea applied after forcing delayed color turning of the peel and slightly increased the incidence and severity of the flesh translucency. The sound, weight, volume, specific gravity of the fruit and crown weight was not affected by the treatment; however the total soluble sugar (oBrix) and titrable acidity were slightly decreased by the treatment even thought the oBrix/Acidity was not altered. Besides, the incidence and severity of flesh translucency and total soluble sugar may increase and flesh titrable acidity may decrease as the yellowing at harvest increased. The time required for turning to complete yellow from color-break and half-yellow harvested fruits at room temperature were 10 and 14 days respectively, and such storage did not affect fruits qualities except some browning of the fruit core was observed. The core browning tended to increased as the amount of urea applied increased. For the fruit harvested between half-to-full yellowing, the core browning was severer and slightly browning and translucency of the flesh was also resulted by the storage. The severity of both was increased as the amount of urea applied increased. For summer fruits, the urea applied after forcing delayed color turning of the peel and dramatically increased the incidence and severity of the flesh translucency. The sound of the fruit was altered by the treatment, and the weight, volume, specific gravity of the fruit was increased by the treatment but the crown weight was not affected. The total soluble sugar (oBrix) and titrable acidity were decreased by the treatment and the oBrix/Acidity was increased. The effect of the peel yellowing at harvest on the qualities of summer fruits was similar to those of the spring fruit except total soluble sugar was not altered in the summer fruits. The fruits harvested between half to full yellowing tended to have slightly core browning and severe flesh translucency tended to increased as the amount of urea applied increased. For the fruit harvested during half to full yellowing, the flesh translucency was severer and slightly browning of the core. The incidence and severity of the core browning were decreased as the amount of urea applied increased, whereas those of flesh translucency were dramatically increased as the urea increased. In conclusion, the best harvest relevant to fruit qualities of the spring and summer were half- to- full yellowing and color-break respectively. The storage, either at room temperature or chilling temperature, may affect the fruit qualities. Core browning may appeared in the spring fruit, and sever flesh translucency may be expected in the summer fruit. The application of urea after forcing may substantially enhanced those deleterious effects.