| 摘要： 蓮霧的產期調節技術經歷數十年的改進，目前蓮霧產期調節已能周年生產應用，但是各個栽培者產期調節處理方法差異大，而常有催花失敗案例，因為蓮霧在修剪後經萌芽抽第三次梢的產期調節中，黑網遮陰處理是催花之前的重要調節步驟。本研究以蓮霧盆栽做30、40、50、60天及未遮陰的對照處理，經催花後21天的開花率以遮陰60天處理最高。各個遮陰處理的全可溶性糖及澱粉含量均顯著較對照的含量低，全氮含量趨勢則正好相反。進一步探討葉片成熟度與內生乙烯的關係，成熟葉的乙烯生成率比淡綠色及老熟葉高。另外再以100ppm磷酸二氫鉀處理，3種葉齡的乙烯生成率都明顯增加，其中以成熟葉最高。結果顯示蓮霧催花與碳水化合物含量可能無直接相關；磷酸二氫鉀處理可有效誘發內生乙烯的生合成，並且在遮陰處理下隨枝條成熟度增加而上升，乙烯可能為誘導開花之重要因素之一。 在同時間修剪，新梢抽出3.5、4.5、5.5及6.5個月進行遮陰處理以探討同時間抽梢，生長至不同成熟度之枝條對遮陰處理之反應，並採葉圓片以磷酸二氫鉀誘導測定乙烯生成。結果顯示，修剪後在6.5個月枝條成熟度經遮陰處理催花後21天，可誘導開花其餘枝條熟度則未有開花現象；另外，持續調查始花期的快慢，則隨著6.5、5.5、4.5及3.5個月的枝條成熟度降低而延長時間開花。以6.5個月枝條熟度配合遮陰處理及環刻處理最早開花，並且在處理磷酸二氫鉀可有效誘發乙烯生成。 蓮霧催花後葉片會有內生乙烯的產生，並且與誘導開花具相關性。所以本研究試驗以乙烯合成酶抑制劑Aminoethoxyvinylglycine (AVG)及乙烯作用抑制劑1-Methylcyclopropene (1-MCP)在催花前、後期處理調查對開花之影響，在催花前處理1-MCP，總開花率有明顯較對照組低，而催花後開花率處理之間沒有顯著差異。另外，1-MCP處理再結合環刻處理，在對照組及1-MCP處理兩者的開花率明顯比較高。催花前應用乙烯抑制劑有顯著降低開花率，顯示，開花與C2H4有密切相關性。 乙烯合成酶抑制劑AVG在催花前、後處理，在未環刻處理下的開花率沒有顯著差異。在環刻處理組的開花率，在催花前處理開花率有顯著差異，而催花後的開花率沒有顯著差異。綜合上述結果，無論是乙烯作用抑制劑(1-MCP)或乙烯合成抑制劑(AVG)，若在催花前處理皆可降低開花，所以乙烯在蓮霧開花過程中應扮演重要的角色。 ‘粉紅’蓮霧在產期調節的流程中，蓮霧花芽分化的時間尚未有明確答案，因此，利用GA3處理擬回推‘粉紅’蓮霧在催花前、後蓮霧花芽創始及分化的時間點。 GA 3處理在催花的前三天、催花當日、催花後三天、催花後六天及催花後九天開花之反應變化，在各個處理的期間都有顯著的抑制及降低開花率，特別在催花前三天及當日最為顯著。然後GA 3應用在催花後三天、催花後六天及催花後九天，在開花時間有明顯提早開花，同時有葉芽及花芽乾枯的比率增加。粉紅種’蓮霧進一步在SEM電子顯微鏡影像及石蠟縱切片下外觀的觀察，對照處理在催花後第九天芽體變為花芽(鏢仔頭期)；另外GA 3處理催花後第十二天芽體變為花芽(鏢仔頭期)。由結果顯示，無論在催花前和後應用GA3後都有降低開花率趨勢，若在催花前應用效果最顯著，所以，花芽分化在拆遮陰黑網至催花和修剪這段時間最為關鍵。 本研究結果顯示，蓮霧產期調節技術後在催花處理動作是刺激誘導,但是也要配合在樹勢的營養狀態、枝及葉成熟度和環境因子，才能有穩定的開花率，並確定蓮霧開花與乙烯有密切關係。Off-season production technique for wax apple have been developed for decades and stable flowering rate can be successfully induced. However, the off-season production techniques utilized by each grower are varied and failure in flower forcing is often observed. Success of flower forcing is closely related to shading treatment. Therefore, the purpose of this research is to investigate the effect of different days of shading treatments on flowering rate of wax apple. Our results indicated that 60 days of shading treatment before flower forcing is needed to achieve stable flowering rate. The starch content of wax apple received 60, 50, 40, or 30 days of shading treatment was lower than that without shading (control) but opposite result was noticed in nitrogen content. The investigation of ethylene production in leaves at different maturity stages revealed that mature leaves had the highest ethylene production. Furthermore, the leaf application of 100 ppm potassium dihydrogen phosphate during shading treatments (60, 50, 40, or 30 days) resulted in an increase of ethylene production especially in mature leaves which showed the highest ethylene production among all treatments. These results indicated that the outcome of flower forcing is not directly related to the carbohydrate content, foliar spray of potassium dihydrogen phosphate may induce ethylene production, and with shading treatments, the amount of ethylene production increased as tree branch matured. Overall, ethylene may play a key role in the regulation of flowering. The shading response of in vitro tree branches at different ages (3.5, 4.5, and 6.5 months after pruning) after 60 days of shading treatment was investigated and ethylene production in leaf disc treated with potassium dihydrogen phosphate was monitored. Our results showed that 21 days of shading treatment in 6.5-month-old wax apple branch was able to induce flowering. In addition, the flower induction in older branches resulted in earlier flowering than younger branches. Moreover, 6.5-month-old branch receiving both shading and girdling treatments showed earliest flowering. Interestingly, potassium dihydrogen phosphate treatment may stimulate ethylene production. After flower forcing, the wax apple leaves may produce ethylene and this may be connected with flower induction. Therefore, the purpose of this study is to investigate the effect of 1-MCP and AVG on flowering when applied before or after flower forcing. Application of 1-MCP before or after flower forcing caused lower flowering rate as compared to that without 1-MCP treatment. In addition, the combination of 1-MCP and girdling before and after flower forcing resulted in higher flowering rate than that treated with 1-MCP only. When the girdling was done at 60 days and 1-MCP was applied at three days before flower forcing, higher flowering rate was recorded relative to that with or without 1-MCP treatment. However, the highest flowering rate was observed in plants treated with girdling alone. Application of AVG before or after flower forcing did not have significant effect on flowering rate. In contrast, application of AVG before flower forcing under girdling condition induced higher flowering rate relative to that without girdling treatment. In addition, all plants treated with AVG had shriveled leaves. Similar results were noticed in all three repeats. Taken together, both the ethylene action inhibitor (1-MCP) or ethylene synthesis inhibitor (AVG) treated before flower forcing may reduce flowering rate, suggesting that ethylene plays an important role in controlling flowering process in wax apple. The regulation of off-season production usually involves stress treatment to alter plant growth and to induce flowering. Up to date, the physiological background of flower bud differentiation in wax apple is still unclear. Therefore, the purpose of this research is to investigate the process of flower bud differentiation by GA3 application before or after flower forcing. Results from application of GA3 at three days before, at the same date, or at three, six, or nine days after flower forcing showed that the flowering rate was inhibited in plants treated with GA3 at three days before and at the same date of flower forcing. Furthermore, the plants treated with GA3 at three, six, or nine days after flower forcing showed early flowering and shriveled leaves. Our SEM results indicated that the flower bud without GA3 treatment appeared at nine days after flower forcing while the flower bud treated with GA3 appeared at 12 days after flower forcing. Based on these results, GA3 application either before or after flower forcing may reduce flowering rate and GA3 treatment before flower forcing had significantly inhibitory effect on flowering. Thus, key timing for flower bud differentiation to take place was during the period when black-net removing, flower forcing and pruning were practiced. Taken together, the off-season production technique is to stimulate flowering and therefore factors affecting the plant’s sink-source condition such as the maturity stages of branch and leaf and environment needs to be taken into consideration. In addition, C2H4 may have close relationship with flower forcing. |
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