瓶插或預措水楊酸溶液對蝴蝶蘭切花品質之影響

Abstract

蝴蝶蘭是台灣重要的外銷切花。業者多以切花保鮮劑延長切花瓶插壽命，維持切花品質。前人研究顯示，水楊酸 (salicylic acid，SA) 具有提升切花吸水量、抑制乙烯生合成或提升花瓣抗氧化酵素活性等作用，然而目前鮮少有關SA處理蘭科切花之研究，故本研究探討SA對蝴蝶蘭切花品質之影響，及SA應用於蝴蝶蘭切花採後處理的可能性。 瓶插液以純水、0.125、0.25、0.5、1.0、1.5、2.0和4.0 mM SA處理大白花蝴蝶蘭(Phalaenopsis Sogo Yukidian ‘V3’)切花。瓶插液處理0.125和0.25 mM SA之切花，瓶插壽命分別較對照組短3及5天，其餘濃度之SA處理與對照組沒有差異，為15至16天。經SA瓶插液處理的切花切口皆提前褐化，且花梗褐化程度較純水組高。濃度大於0.5 mM SA的瓶插液處理中，花序梗滲出水珠，且水珠的數量隨SA濃度提高而上升。處理2.0和4.0 mM SA瓶插液的切花，於瓶插後期落花數上升且相對鮮重下降。瓶插測試中低濃度SA降低蝴蝶蘭‘V3’切花瓶插壽命，而高濃度SA瓶插液雖不影響瓶插壽命，但長時間瓶插後切花品質迅速劣化。 後續試驗縮短SA處理時間，以純水、0.0625、0.125、0.25、0.5、1.0和2.0 mM SA預措切花24小時，再轉移至純水中瓶插。最高濃度2.0 mM SA處理之瓶插壽命較純水處理延長3天。進一步測試高濃度SA之預措效果，處理0.5、1.0、2.0、4.0、8.0和16.0 mM。此試驗中所有SA預措濃度均縮短切花瓶插壽命，以16.0 mM處理之瓶插壽命最短，為13天；純水組瓶插壽命最長，為43.7天。切花經SA預措，切口褐化皆較純水處理提早且更為嚴重。預措8.0和16.0 mM SA處理的切花花梗滲出水珠，且兩處理之花朵分別於瓶插第14天和第11.8天提前掉落。 水楊酸處理發生提早落花、花梗褐化及花梗滲出液等徵狀，因此將蝴蝶蘭切花瓶插於純水或經16.0 mM SA預措24小時後，觀察花序梗及小花柄離層區之細胞結構變化。預措SA相對於純水處理，花序梗中細胞膜與細胞壁分離、皮層細胞色素流失，以及基本組織的薄壁細胞結構破損；小花柄離層區之細胞提前大約14天分離。預措SA處理組提前落花，落花之乾、鮮重皆較對照組高，顯示預措SA後花朵在相對新鮮的狀態發生離層。本研究結果顯示SA作為瓶插液或預措液皆無法維持蝴蝶蘭切花瓶插品質，SA處理濃度越高，可能使切花瓶插品質下降，不適合應用於蝴蝶蘭切花採後處理。

Phalaenopsis is an important cut flower in Taiwan for export. Preservatives are used in the cut flower industry to extend vase life and maintain cut flower quality. Literature shows that salicylic acid (SA) improves water absorption, inhibits ethylene biosynthesis, and increases the activity of antioxidant enzymes in petals of cut flowers. However, only a few studies investigated the effects of SA on cut orchids. Therefore, this study investigated the effects of SA on the quality of Phalaenopsis cut flowers and the anatomical structures and explored the possibility of SA application on the postharvest of Phalaenopsis cut flowers. Phalaenopsis Sogo Yukidian ‘V3’ cut flowers were placed in the vase solutions containing water, 0.125, 0.25, 0.5, 1.0, 1.5, or 2.0 mM SA. In vase solutions treated with 0.125 and 0.25 mM SA, the vase life was 3 and 5 days shorter than the control. The vase life of the other SA treatments was 15 to 16 days, which were not significantly different from the control. The inflorescence incision exhibited earlier browning, and the browning length was longer with SA treatments. With the SA concentrations greater than 0.5 mM, exudates leaked from the inflorescence, and the number of exudates increased as the SA concentration increased. The number of dropped florets rose significantly in the 2.0 mM and 4.0 mM SA treatments during the later stage in vase. The lower SA concentrations in preservatives shortened the vase life of Phalaenopsis Sogo Yukidian ‘V3’ but higher SA concentrations did not influence the vase life. However, after a long period in the high concentration of SA preservatives, the cut flower quality decreased significantly in the late stage of vase life. Therefore, we shortened the SA treatment duration and pulsed the cut flowers in water, 0.0625, 0.125, 0.25, 0.5, 1.0, or 2.0 mM SA pulsing solution for 24 hours, then transferred them to water. The vase life of the highest concentration treatment, 2.0 mM SA, was the longest. Then we further applied the pulsing solution with higher SA concentrations of 0.5, 1.0, 2.0, 4.0, 8.0, or 16.0 mM. All concentrations of SA pulsing solution reduced the vase life of Phalaenopsis cut flowers in this experiment. The cut flowers treated with 16.0 mM SA pulsing had the shortest vase life, which was 13 days, while the vase life of the control was 43.7 days, the longest among all treatments. Inflorescence incision got browning earlier with all SA pulsing treatments. The peduncle produced exudates when treated with 8.0 and 16.0 mM SA, and these two treatments had the earliest floret drops that occurred on 11.8 and 14.0 days in a vase, respectively. The symptoms, such as early floret drop, peduncle browning, and exudate production, occurred in Phalaenopsis cut flowers after being treated with SA. Cut flowers were placed in water or 16.0 mM SA pulsing solution for 24 hours and then transferred to water. We investigated the effects of the two treatments on the cell structure changes of the peduncle and pedicel abscission zone during the vase life. With 16.0 mM SA pulsing solution, peduncle cells showed protoplast shrinkage and separation from the cell wall. Cortical cells near the epidermis exhibited pigment loss. Parenchyma cells in the ground tissue were damaged. Abscission zone cells separated 14 days earlier than the control. Browning was limited around the peduncle incision in the control. The dry and fresh weights of dropped florets of SA treatment were higher than those in the control, indicating they were fresher than the control when the florets dropped. Results showed that neither the SA vase solution nor the SA pulsing solution could maintain Phalaenopsis cut flower quality. As concentration of SA increased, the cut flower quality decreased. Therefore, SA may not be suitable for Phalaenopsis cut flower postharvest.