Effect of Fenitrothion and Potassium Dihydrogen phosphate on the Flowering of ''Pink'' wax-apple.

蓮霧目前催花所使用的撲滅松，屬於有機磷殺蟲劑，對施用者及生態皆有安全疑慮，需尋找出替代藥劑。因撲滅松與落葉有關，而國外研究發現，磷酸二氫鉀可作採收脫落劑，故本試驗之目的，在探討以磷酸二氫鉀取代撲滅松的可能性，及磷酸二氫鉀催花的可能機制。 誘導蓮霧落葉試驗，是以瓶插來了解藥劑溶液的吸收及其影響。經處理之後， KH2PO4處理者之葉片有脫落及產生水浸狀現象，Ethrel會造成葉緣焦枯產生，而Fenitrothion引起枝條乾枯；處理後，之分析葉片磷及鉀含量，在磷酸二氫鉀處理者有較高的磷含量。磷酸二氫鉀濃度與乙烯及落葉能力有關，乙烯釋放率隨著濃度增加而上升，在第三天出現乙烯高峰，至第七天，100 mM KH2PO4濃度以上有落葉現象，葉片磷及鉀的含量也隨KH2PO4濃度增加。 另外，測定葉圓片的乙烯釋放率及呼吸率，結果與瓶插試驗相似。在添加Mannitol緩衝液處理，同樣具有誘發乙烯能力，在高濃度下呼吸率會增加。在前人研究中，已知磷酸鹽、鈉及鉀複合物均有誘發乙烯能力，在磷酸二氫鉀及磷酸二氫鈉處理，皆具有誘發乙烯的能力，而氯化鉀沒有誘發能力，顯示磷酸二氫鉀的效果最佳；因此，磷酸根應為重要誘發乙烯合成的因子。此外，乙烯誘發受到光強度影響，在高光強度下能顯著誘發乙烯，而乙烯釋放率隨著光度降低減少。 在加乙烯抑制劑探討葉圓片乙烯釋放的試驗中，結果顯示：添加AVG及CHI後，顯著抑制乙烯合成，而在AVG處理呼吸率有增加現象；另外，在抑制劑處理前，燻蒸1-MCP，磷酸二氫鉀仍然有誘發乙烯能力，而添加AVG及CHI後，同樣能顯著抑制乙烯誘發，亦即顯示磷酸二氫鉀誘發乙烯，合成的途徑和一般乙烯合成途徑應相似。 在田間以Fenitrothion及KH2PO4進行催花處理，碳水化合物的含量差異顯著。在催花後葉綠素及螢光含量逐漸增加，磷酸二氫鉀處理者，較快誘導花芽出現，但蓮霧花芽的誘導受到氣候因素限制；蓮霧採收之後果實品質(顏色、糖度、硬度及裂果率)，不受到兩種藥劑影響。由結果顯示，KH2PO4應可取代Fenitrothion，應用在蓮霧催花的處理。The objective of this study was to find a chemical compound to substitute fenitrothion as the flower advancing agent of wax apple trees. Fenitrothion, classified as an organophosphate pesticide, has been used to advance blooming for some time. Due to its negative side effects on farmers' health and ecological concern, searching for a new agent as a replacement has become necessary. Various reports indicated that KH2PO4 has been effective in the post-harvest defoliation, and played a role in flower initiation. Thus experiment has been designed to test the possibility of replacing fenitrothion with KH2PO4 in the advancing flower of wax-apple. By dipping a wax-apple branch in KH2PO4 solution in stem-feeding system, leaves showed signs of abscission and water soaking. The tendency was similar to those treated with ethrel or fenitrothion. Samples treated with KH2PO4, ethrel and fenitrothion were analyzed for their potassium and phosphate contents. KH2PO4 treated had the highest phosphate concentration. Ethylene production was also proportional to the concentration of KH2PO4. Ethylene peaked on the third day after the treatment of 100 mM KH2PO4 and abscission started on the seventh day. Leaf disc experiments were conducted to determine the ethylene production and CO2 release. Wax-apple leaf-dises treated with KH2PO4 or NaH2PO4 showed that the rate of ethylene release was proportional to the concentration of either compound, though KH2PO4 treated was superior. There was no response in KCl treated disc. This result demonstrated that phosphate was the major factor for inducing ethylene production. Mannitol solution was used as a buffer and no effect on the KH2PO4-induced ethylene production. The leaf discs of releasing rate of ethylene is influenced by light intensity. Effect the ethylene production apparently under high light intensity, as the intensity reduces the releasing rate of ethylene to reduce. Adding inhibitors AVG, CHI, 1-MCP separately to KH2PO4-treated leaf discs, ethylene production was significantly reduced by AVG and CHI, and not affected by 1-MCP. But inhibition took effect when AVG or CHI was added to the1-MCP treated sample. This seemed to explain that the biosynthesis of ethylene induced by KH2PO4 was similar to the general pathway of ethylene synthesis in the plant. In field experiments both fenitrothion and KH2PO4 caused a change in carbohydrate concentration and a faster flowering was induced by KH2PO4. After evocation activated by fenitrothion or KH2PO4, chlorophyll and chlorophyll flurometric parameter (Fv/Fm) increased gradually. Wax-apple evocation often limited by climatic conditions but the post-harvest fruit qualities were not affected by either chemical treatment. According to the results of this study, it shows that KH2PO4 can be a wax-apple flower advancing agent instead of fenitrothion in the field application.中文摘要 i Summary ii 總目錄 iv 表目錄 v 圖目錄 vi 壹、前言 1 貳、前人研究 3 一、蓮霧產期調節之技術 3 二、植物荷爾蒙及環境因子對果樹開花之影響 5 三、化學藥劑在誘導開花及產期調節之應用 8 四、誘導落葉之化學藥劑 9 五、抑制劑對落葉之影響 11 六、磷酸二氫鉀的化學性質與應用 12 七、撲滅松之化學特性及應用 14 參、材料方法 15 一、試驗材料 15 二、試驗方法 15 三、分析項目及方法 18 肆、結果 22 一、Fenitrothion及KH2PO4田間催花處理方法對開花率、果實品質及葉片 葉綠素螢光、葉綠素及碳水化合物之影響 22 二、KH2PO4對蓮霧枝條及葉圓片乙烯釋放及呼吸率變化之影響 56 伍、討論 80 一、KH2PO4應用在蓮霧催花的可行性 80 二、KH2PO4對蓮霧枝條及葉圓片乙烯釋放及呼吸率之變化 84 參考文獻 8