鳳梨果梗創口污斑發生之研究

Abstract

摘要-果梗創口污斑(Peduncle detachment surface discoloration, PDSD)是鳳梨採收後易發生的症狀，且影響品質甚鉅。為解決鳳梨PDSD之問題，本研究探討‛台農17號’鳳梨果實於採收前或採收後採用防範措施之效果。在PDSD之影響因子探討方面，調查品種、收穫季節、果實大小和採收成熟度之影響。其次，在採前利用亞磷酸鉀水溶液(Potassium phosphite, KPhi)探討濃度、使用次數及施用方法等，對鳳梨果實外觀特性及PDSD之影響。第三部分則是針對可能適合未來栽培、生理失調程度較低的新品種之選育過程。 結果顯示，鳳梨的PDSD常於採收後3至4天顯現，之後嚴重程度迅速加重，尤其是當鳳梨果實置於室溫(25°C)下，且環境相對濕度較高時變色更快，此與微生物快速滋長可能有關。果實採收前噴灑亞磷酸鉀(KPhi)水溶液，則果實PDSD之嚴重程度可較對照者(僅噴水)大幅降低。如施用濃度達10 g·L-1，雖較早轉色，然採收當天的果實冠葉及外觀，均較其他處理者差，此結果顯示，KPhi可有效降低PDSD，但使用時需考慮濃度、施用頻率及次數。此外，PDSD與果梗基部切面內側變色(Proximal end of fruit core discoloration; PEFCD)之間呈同時增加之關係，而採前施用KPhi水溶液可減輕PDSD和PEFCD之症狀。 最後，亦調查鳳梨新品種‘台農23號’ (TNG.23，農民稱為芒果鳳梨)，包括PDSD發生狀況等特性。本品種係由農業試驗所嘉義農業試驗分所，自1991年至2018年進行選育而獲得，該品種重要園藝性狀為植株矮、葉片短，適合機械化輔助管理，果實大小適中，且果實之生理失調發生率低，PDSD亦較輕微，與台灣目前廣泛栽培之品種不同，可生產果實品質佳之夏果。

Abstract-In this study, I investigated the fruit appearance characteristics and quality changes of pineapple fruit stored at different store temperatures, and also the occurrence, development of pineapple peduncle detachment surface discoloration (PDSD). In order to solve PDSD problem of ‘Tainung No.17 (TNG.17, also known as ‘Golden Diamond’) by pre- and post- harvest treatment, different preventive measures against PDSD were treated. To begin with the understanding of causes and factors behind pineapple PDSD, I analyzed the development of PDSD of different varieties, harvest seasons, fruit sizes, and maturity stages at harvest. Then, effects on fruit appearance characteristics and PDSD were measured under different potassium phosphite (KPhi) concentration, frequency of application, and methods of application. Finally, I focused on the research of new variety ‘Tainung No.23’ (TNG.23, also known as mango pineapple) which was with less physiological disorders, and may be suitable for the future of pineapple production. Pineapple PDSD often appeared 3 to 4 days after harvest at room temperature (25°C), and became more serious in the conditions of higher relative humidity and higher microbes growth rate. I has found out that with pre-harvest treatment of spraying KPhi, PDSD degree and index declined and significantly lower than those of fruits with water-only spraying. However, when the concentration of KPhi reached 10 g·L-1, the color change in pineapple fruit skin color was earlier, but with worse appearance of crown leaves and shells at harvest. As a result, KPhi could effectively reduce pineapple PDSD in adequate KPhi concentrations, frequency of application, and methods of application. Furthermore, percentage discoloration of proximal end of the fruit core discoloration (PEFCD) increased when PDSD increase, and both PDSD and PEFCD symptoms reduced with KPhi treatment. Last, we described the new breeding variety named ‘Tainung No.23’ was selective breedings at Chiayi Agricultural Experiment Station, Taiwan Agricultural Research Institute (CAES-TARI) pineapple breeding orchard from 1991 to 2018. This new cultivar was characterized by very short plant height, short leaf length, and suitable for management system for auxiliary mechanization operations. The fruit of ‘TNG.23’ with moderate size and less physiological disorders, and different from the current and widespread cultivars, was with good quality at harvest in summer.