除芽對文心蘭生長與開花之影響及文心蘭切花內碳水化合物之運移

文心蘭 (Oncidesa spp.) 是臺灣最重要的切花作物之一，2017年出口產值達1196萬美金。然而文心蘭業者面臨產量高峰期 (5-6月和9-12月) 導致切花售價低的問題，因此迫切尋找簡單有效的產期調節方法。文心蘭切花主要外銷至日本，其採後生理研究重要，但文心蘭的花朵展開機制和採後花序內養分變化運移相關科學研究尚缺，又因文心蘭乃總狀花序，增加研究上難度。本研究的試驗一係對台中和雲林地區文心蘭 (Oncidesa Gower Ramsey ‘Honey Angel’) 進行週年性除芽處理 (一種操作簡易的產期調節方式)，探討對其後續生長、開花及產期的影響。結果發現兩地區除芽後，總芽體數上升，主要是因為除芽促進前二代莖上芽體之萌發。儘管除芽處理對文心蘭的新生假球莖和開花品質產生一定的負面影響，包括新生假球莖變小、花序高度下降和分支數減少等，仍有部分月份 (台中11月、雲林4、6和9月) 的除芽植株切花等級上升，可能與試驗選取生長旺盛的年輕植株相關。比較兩地區產期差異時，發現兩地溫度差異乃重要影響因素。若以避開產期高峰期為目的，夏季時期，於台中栽培之植株可在6月中進行除芽，而雲林之植株則需提前到5月中至6月中；冬季時期，台中業者可在10月中對植株進行除芽，雲林業者則需延後至10月底至11月底進行。本研究的試驗二從碳水化合物角度瞭解文心蘭‘Honey Angel’花朵展開機制。隨著花苞成熟膨大至展開，它的鮮重、乾重和鮮乾重比上升，並伴隨著葡萄糖和果糖濃度上升，蔗糖、水溶性多醣濃度維持穩定，而澱粉濃度在花朵展開後大幅上升。觀察單一花苞在瓶插期間 (瓶插液為100 mg·L-1 8-HQC ，未供應其他外源碳水化合物) 的展開過程，其鮮重、乾重、鮮乾重比、葡萄糖和果糖濃度上升。花苞水溶性多醣濃度在瓶插8天後呈顯著下降趨勢，而澱粉濃度則未下降。可溶性醣類濃度的上升一方面源於水溶性多醣水解，另一方面則是從其他組織器官獲取額外碳水化合物。試驗三和試驗四之目的為瞭解文心蘭‘Honey Angel’切花採後在無外源碳水化合物供應下，花序上花苞、已開放小花和花莖間營養物質競爭運移之關係。在瓶插的後期 (瓶插日大於11天)，下位已展開小花的存在可增加上位花苞展開數，但上位花苞的存在使下位已展開小花凋落嚴重，顯示營養物質由下位已展開小花運移至上位花苞之可能性。在瓶插的前期 (瓶插日小於8天)，主花莖則是上位花苞的主要碳水化合物的供源。雖下位已展開小花可作為上位花苞之供源，但當有主花莖存在時它會與上位花苞競爭主花莖之碳水化合物。本論文之除芽試驗可為台灣文心蘭業者提供產期調節的實務資訊；花朵展開機制和花序內營養物質運移的研究是文心蘭採後生理的重要基礎研究。

關鍵字

文心蘭；除芽；花朵展開機制；碳水化合物；養分運移； LED

並列摘要

Oncidesa is one of the most important cut flowers in Taiwan, which generated an export value of 11.96 million USD in 2017. Low sale price in the high-peak harvest seasons (May-June and September-December) is a serious problem faced by growers in Taiwan. Therefore, finding an effective flowering regulation method is needed. On the other hand, research of postharvest physiology on Oncidesa cut flower is very important, since most of Oncidesa cut flowers produced in Taiwan are exported to Japan. Till now, no reference is available on the floret opening mechanism and nutrient mobilization within inflorescence in Oncidesa. Furthermore, related researches on Oncidesa are much more difficult because its inflorescence is a raceme. To comprehensively understand the effect of new shoots excision on the growth, flowering and production period of Oncidesa Gower Ramsey ‘Honey Angel’, year-round new shoot excision was carried out in Taichung and Yunlin in the first experiment of this thesis. Results showed that new shoots excision treatment increased number of total vegetative buds in both districts, attributed to the emergence of vegetative buds from the second back shoot stimulated by new shoots excision. Although new shoots excision treatment did have some negative effects on the newly grown pseudobulb and inflorescence, including diminishing the growth of newly grown pseudobulb, shortening inflorescence height, and decline in the number of branches, cut flowers grading of excision-treated plants in several months occasionally increased (compared with their controls), which might be due to young and vigorous growing plants used in this experiment. We also found that temperature difference in Taichung and Yunlin is a key factor influencing the production period difference between the two districts. For the purpose of avoiding high-peak harvest seasons, new shoots excision treatment can be done on mid-June in Taichung during summer, same treatment should be advanced to mid-May to mid-June in Yunlin. In winter, growers in Taichung can perform new shoots excision in mid-October, while growers in Yunlin are suggested to do the excision in late-October but before mid-November to achieve the same flowering regulation effect. In the second experiment of this thesis, we focused on the floret opening mechanism from the perspective of carbohydrate metabolism. With the bud maturing and opening, its fresh weight (FW), dry weight (DW), FW/DW ratio, concentration of glucose and fructose rose continuously, while concentrations of sucrose and water soluble polysaccharides stayed stable. In addition, concentration of starch increased dramatically after buds opened. With the opening of a single flower buds, while inflorescence was keeping in 100 mg·L-1 8-HQC vase solution (without any exogenous carbohydrate), its FW, DW, FW/DW ratio, concentrations of glucose and fructose increased continuously. Since concentration of starch did not decrease after 8 days, the increase soluble carbohydrates came from the breakdown of water soluble polysaccharides, or carbohydrates transported from other tissues and organs. The third and fourth experiments were done to understand carbohydrate translocation/competition among buds, opened florets, and stalk within an Oncidesa Gower Ramsey ‘Honey Angel’ inflorescence, in the case of without any exogenous carbohydrate supplement. We found that the existence of basal florets improved the opening of upper buds in the late vase days (more than 11 days), but basal opened florets withered severely if upper buds existed in the inflorescence, which indicated nutrient might transport from basal opened florets to upper buds. During the early vase days (within 8 days), main stalk was a major carbohydrate source for upper buds. Although basal opened florets can be a carbohydrate source to upper buds in the late phase, it competed with upper buds for carbohydrates, when main stalk was an available source within an inflorescence. New shoot excision experiment in this thesis providates useful information to Oncidesa growers in Taiwan. Experiments about florets opening mechanism and nutrients mobilization within an inflorescence are important basic researches in post-harvest physiology in Oncidesa.