|摘要： 番石榴(Psidium guajava L.)在台灣因產期調節技術佳，周年生產，但台灣夏季多雨氣候使番石榴營養生長過於旺盛，果實養分因葉片的競爭導致品質不佳，連帶使貯藏能力下降，造成外銷上之損耗增加，台灣為東方果實蠅(Bactroceradorsalis)疫區，慣行栽培皆使用 PE (polyethylene)袋加上內襯舒果網(expandedpolystyrene net sleeve, EPNS)進行果實套袋，但此法耗費大量人力與資材成本，造成農業廢棄物增加問題，且慣行套袋栽培之番石榴生長較快，夏季果實常碩大而無味。本論文探討網室內無套袋栽培、硫酸鎂處理與環剝處理等方式，試圖改善夏季番石榴果實品質提升果實低溫貯運能力。 網室內無套袋處理之‘珍珠’番石榴(Psidium guajava L. cv. Jen-Ju)果實，夏季生育期較套袋處理果實約晚 10 天(76 天)成熟，冬季則較套袋處理延遲 7 天成熟(114 天)，無套袋處理之果實成熟時外觀與剖面均與套袋處理者相似，冬果品質也與套袋處理者相同，夏果抗壞血酸、礦物元素鈣、鎂、銅、鐵等含量較高，生育期間鈣與抗壞血酸含量較套袋處理者高且穩定，果實官能品評評分最佳。在貯藏表現上，無套袋處理之果實，在貯藏期間維持較高的硬度、可溶性固形物與抗壞血酸。 硫酸鎂處理之葉片葉綠素 a、b、總葉綠素、鈣、鎂與錳含量較高，果實重量、長、寬徑、可溶性固形物、抗壞血酸與碳水化合物含量也較對照組高。 環剝後 97-168 天之‘珍珠’番石榴營養生長受到抑制，但花朵與果實總數上升，葉片錳與鋅含量下降，葉片碳水化合物含量較高，果實重量、長、寬徑、硬度與抗壞血酸含量增加。 上述處理皆可有效提升‘珍珠’番石榴果實的品質與低溫貯運能力，改善外銷貯運的果實品質，也降低損耗。In Taiwan, year-round production of guava (Psidium guajava L. cv. Jen-Ju) can be achieved by off-season production technology. However, due to its strong vegetative growth in summer that competes for nutrients, the fruit quality is often reduced and the low temperature storage ability is lowered causing losses in export earning. Taiwan is the epidemic area of Bactrocera dorsalis, the conventional culture of guava involves bagging fruit with polyethylene bag containing expanded polystyrene net sleeve. The bagging process is not only labor-intensive but also generating agricultural wastes problems. Furthermore, fruits produced with conventional culture, had huge size but bad taste. Therefore, the objective of this study is to investigate the effect of non-bagging culture, magnesium sulfate spraying, and girdling on the improvement of guava fruit quality and storage ability. Our results showed that‘Jen-Ju’guava with non-bagging culture has a growth period 10 days (76 days after bagging) and 7 days (114 days after bagging) longer than that of conventional culture in summer and winter respectively. Similar fruit appearance was observed between non-bagging culture and conventional culture. In winter, non-bagging fruit quality was equally good as compared with that of the bagging fruit. Fruit in summer had higher contents of ascorbic acid, copper, iron, calcium and magnesium. Non-bagging fruit had higher and stable contents of calcium and ascorbic acid, and received highest score in terms of sensory evaluation. In addition, non-bagging fruit had greater performance on fruit firmness, total soluble solids and ascorbic acid. Magnesium sulfate treatment in leaves resulted in higher chlorophyll a, b, chlorophyll a+b, calcium, magnesium and manganese contents in leaves. In non-bagging fruits, larger weight, length, width, total soluble solids, ascorbic acid and carbohydrates were detected relative to those of bagging fruits. After 97-168 days of girdling, vegetative growth of ‘Jen-Ju’guava was inhibited; but reproductive growth was promoted. In girdled trees, the total number of flowers and fruits were higher than those of the non-girdled control. Leaf from girdled trees had lower contents of manganese and zinc; but carbohydrates were higher. Fruits with girdling treatment showed increased weight, length, width, firmness, and ascorbic acid. Thus, the data support that non-bagging culture, magnesium sulfate spraying, and girdling can effectively increase fruit quality of ‘Jen-Ju’guava, enhance it''s low temperature storage ability, and reduce losses during overseas trasportation.