| 摘要： 台灣‘愛文’芒果(Mangifera indica L. cv. Irwin)在外銷時所遇到的困境，以外觀最具影響力。近年發現在愛文芒果果實成熟後出現轉色上的問題日益嚴重，即於果梗端之果皮仍呈現綠色，且果肉不具後熟能力。本研究比較了正常成熟果與綠頭果之差異，發現綠頭症果實頂端之硬度明顯高於正常果實，在糖度的比較中，正常果是較高的。利用色差儀測得綠頭症果實果皮a*值顯著低於正常果，呈現偏綠的顏色。乙烯釋放率的結果顯示綠頭果較正常果有較低的乙烯釋放率，而呼吸率在正常果與綠頭果間沒有顯著差異。 為探討成因，欲以尿素施肥，嘗試誘導植株在高氮素處理後是否產生此症狀。在果實發育期中一週一次處理，每株噴施1000 ppm並於樹冠下方施用1公斤尿素，持續三週，於第四週和果實成熟期採樣，皆進行品質測定、全可溶性糖、澱粉及元素分析。結果顯示過量的氮肥會使果實品質下降，如硬度及全可溶性糖、而果皮在果肩部位並沒有出現如綠頭果實般的綠頭症狀、氮元素在過量氮肥之試驗中也沒有顯現出差異，因此推斷過量的氮肥可能並非誘發芒果綠頭症的原因。In Taiwan, Mangifera indica L. cv. Irwin encounters some problems when exporting to other countries. The most serious one in marketing is the appearance of mango fruit. In recent years, ‘Irwin’ had found some trouble in turning red after maturity. The syndrome includes green fruit peel at the fruit shoulder and the pulp fails to ripe. The objectives of this study are to compare some basic maturity characters in normal mango fruit (CK) and ‘green head’ fruit (GH). In firmness test, the shoulder of GH fruit was significantly harder than CK fruit. The CK fruit showed a higher total soluble solid content compared with GH fruit. Using colorimeter to analyze fruit shoulder peel fragments. Indicated that the a* value of GH fruit is significantly lower than CK fruit, representing the fruit peel is more green. Analysis of ethylene release rate showed that GH fruit had a lower rate than CK fruit, and no significant difference in respiration rate can be observed between CK and GH fruit. In order to investigate the cause of green head, urea was used to induce this symptom. During the fruit development period, urea was sprayed and fertilized once a week with 1000 ppm on the whole mango tree and 5 kg for each tree for three weeks. At the fourth week and fruits matured, samples were taken and analyzed. Results indicated that firmness and total soluble sugar are significantly decrease between treatment and control groups. And the color at fruit shoulder did not appear greening in treatment group. As well as the nitrogen element did not show difference between treatment and control groups. Thus we can inferred that nitrogen overdose may not be the reason causing “Green-head” in mango fruit. |
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