| Summary: | 碩士 === 國立臺灣大學 === 園藝學研究所 === 100 === 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.
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