生長調節劑對九重葛及百香果生長及開花之影響

Effects of Plant Growth Regulators on the Growth and Flowering of Bougainvillea spp. and Passiflora spp.

劉芳吟(Fang-Yin Liu)

指導教授 ： 張育森

國立臺灣大學/生物資源暨農學院/園藝學研究所/博士(2010年)

https://doi.org/10.6342/NTU.2010.02846

摘要

九重葛為熱帶及亞熱帶地區重要花卉，花期的調控及觀賞壽命為產業的重要課題。但九重葛在開花後常有易落苞的問題存在，尤其在室內及陰雨的低光環境下最為嚴重，影響其觀賞品質。本研究擬探討生長調節劑對九重葛生長及開花之影響並探討如何延長九重葛之苞片壽命，以增進觀賞價值。
九重葛‘紫花’在自然環境下，開花枝條中以傾斜枝條 (inclined shoot) 佔大多數，水平枝條(horizontal shoot) 次之，而直立枝條(vertical shoot)皆為徒長枝，開花率最差。但仍缺少證據證明為何傾斜枝條較易開花。本研究將九重葛‘台北紅’利用人工拉枝分為傾斜、水平及直立枝條，結果顯示九重葛的枝條形態以傾斜枝條與水平枝條之營養生長較直立枝條生長緩慢，且到達開花所需時間較短、花芽數也較多，其中以傾斜枝條具有最佳促進九重葛開花之效果;由內生氨基環丙烷羧酸 (1-aminocyclopropene-1-carboxylate, ACC)含量測定得知，傾斜枝條之ACC含量高於水平枝條及直立枝條，因此乙烯可能扮演促進枝條成熟並提早花芽形成之角色。另以不同時期枝條成熟度(營養生長時期、刺花序軸肥大、花苞可見、花苞開放時期)的枝條分別處理乙烯釋放劑- ethephon，證明九重葛在營養生長時期施用ethephon可以加速枝條成熟，且其內生ACC含量低於生殖生長階段，故此時處理ethephon可提高九重葛內生乙烯含量而達到促進花芽形成之效果; 而在生殖生長時期(刺花序軸肥大、花苞可見、花苞開放時期)施用ethephon反而不利之後花苞的發育，且其內生ACC含量高於營養生長階段，因而會造成嚴重的落苞及落葉現象。由以上結果推論乙烯在九重葛上具有促進花芽形成和抑制花芽發育之雙重作用。
在花苞壽命方面，將九重葛‘台北紅’處理100-800 nL L-1甲基環丙烯 (1-methylcyclopropene, 1-MCP) 與對照組相比顯示出具有延長苞片壽命的效果，以800 nL L-11-MCP的效果最好，但只在苞片較成熟(stages 3-4)才有顯著延長苞片壽命之效果。而在苞片較幼嫩時(stages 1-2)則無顯著延長苞片壽命之效果。另外處理單一藥劑1-MCP、萘乙酸 (1-naphthaleneacetic acid, NAA)、萘乙酸鈉 (sodium salt of naphthaleneacetic acid, SNA)、苯氨基嘌呤 (6-benzylaminopurine, BA)、腐胺 (diamine putrescine, Put)、水楊酸 (salicylic acid, SA)和硫代硫酸銀(silver thiosulfate, STS)與對照組相比皆具有顯著延長苞片壽命之效果，其內生ACC 氧化酶 (1-aminocyclopropene-1-carboxylate oxidase, ACC oxidase)及乙烯含量也會顯著地降低。但處理吲哚丁酸 (indolebutyric acid, IBA)及磷酸二氫鉀(potassium dihydrogen phosphate, KH2PO4)則在苞片任一時期皆無延長苞片壽命之效果且其內生ACC oxidase及乙烯含量與對照組相比亦無顯著差異。生長調節劑組合方面，以NAA+ SA及NAA + STS具有最佳延長苞片壽命之效果且可降低內生ACC oxidase含量、乙烯含量、減緩葉綠素和蛋白質的降解。整體效果而言，複合藥劑優於單一藥劑且可延長各個時期苞片的壽命。
百香果(Passiflora spp.)為西番蓮科西番蓮屬多年生蔓生植物，然而其在台灣冬季低溫下常有不開花之情形存在，常會造成春季果實供應量的短缺。本研究擬探討低溫環境下處理生長調節劑對百香果‘台農1號’生長及花芽形成之影響，期許能解決百香果在冬季低溫下之開花障礙。
在低溫下施用乙烯作用抑制劑(STS、AgNO3)顯示出具有促進花芽形成之效果，約處理後2星期即可看見花芽，且可以降低其內生ACC含量、ACC oxidase及乙烯含量。但花芽出現之後會有夭折之情形，無法順利開花。推測其可能原因為花芽出現後又遭受到低溫的逆境而致使花芽無法膨大，或施用藥劑時植株仍太小，對逆境的抵抗力不強所導致。
若將百香果植株先在低溫環境(20/15℃)下施AgNO3和STS誘導花芽形成後，再移溫至25/20℃，其花芽仍可持續發育，且花芽會順利發育至開花。另外枝條成熟度也會影響百香果對低溫的抵抗性，將百香果植株依節數分成三個階段(P1, 5-11節、P2, 12-18節、P3, 19-25節)，分別噴施1 mM STS，置於冬季低溫環境下，觀察其開花情形。顯示出枝條較幼嫩之植株在誘導花芽形成之後會受到冷害，花芽皆夭折，夭折率達100%; 而枝條較成熟之植株(P2, P3)，其枝條較成熟，故花芽能繼續發育至開花。
水楊酸具有抑制乙烯之作用且可以抵抗生物及非生物逆境，對植物的生長及發育具有重要的影響。不同pH值的水楊酸其對百香果的生長效能具有顯著的影響。在低溫下處理pH 6.5的水楊酸溶液可以促進百香果生長及花芽形成，但若是處理pH 2.4的水楊酸溶液之植株則生長緩慢，且均無花芽形成。水楊酸也具有濃度效應，枝條較幼嫩植株(P1, 5-11節)之百香果需較高的濃度的SA (2.5 mM以上)才有促進其花芽形成之效果;而枝條較成熟(P2, 12-18節)之百香果僅需較低濃度的水楊酸(0.5-2.0 mM)即可達到促進花芽形成之效果。在低溫下處理水楊酸雖可使花芽繼續發育至開花，但仍有花芽夭折率高之情形。若將百香果植株(P2, 12-18節)先在低溫環境(20/15℃)下處理水楊酸誘導花芽形成後，移溫25/20℃，其花芽可持續發育並且可以降低花芽夭折率，花芽會順利發育至開花。

關鍵字

九重葛 ； 百香果 ； 乙烯 ； 開花

並列摘要

Bougainvillea (Bougainvillea spp.) is an economically important ornamental flower in sub-tropical and tropical regions. Therefore, the ability to control the timing of flower production is of great importance commercially. After flowering, the flower bracts regularly abscise, and this process increases when bougainvilleas are subjected to indoor low-light conditions. Therefore, the aim of this research is to elucidate how plant growth regulators affect the growth and flowering of bougainvillea.
Most of the bougainvillea flowering shoots are inclining and vertical shoots are not flowering shoots, thus confirming the above observations in the natural environment. However, no direct or other studies have been performed to determine why inclined shoots have more flowers than vertical and horizontal shoots in the natural environment. In this work, therefore, bougainvillea shoots were artificially orientated vertically, horizontally and at an incline to study the effect of orientation on plant growth and the development of flower buds. Inclined shoots of bougainvillea have more flowering buds and more fully blooming flowers than either horizontal or vertical shoots. Inclined shoots had a higher endogenous ACC (1-aminocyclopropene-1-carboxylate) content and produced more ethylene than either horizontal or vertical shoots, indicating that more ACC in the inclined shoot is converted into ethylene, and the higher ethylene concentration in the inclined shoot causes it to mature earlier and flower sooner.
Additionally, this study examined bougainvillea shoots of different developmental stages, e.g., vegetative shoot, flowering shoot stage 1 with the thorn-inflorescence axis developed fully (FS1), flowering shoot stage 2 with visible flower bud (FS2), and flowering shoot stage 3 with blooming shoot (FS3) following their treatment with ethephon (2-chloroethylphosphonic acid). Experimental results indicated that ethephon treatment of the vegetative shoot of bougainvillea accelerates its shoot maturity and enhances flower formation. The same treatment also increases endogenous ethylene production of the vegetative shoot, subsequently facilitating flower formation in which the endogenous ACC content is lower than that of reproductive shoots (FS1, FS2, and FS3). Moreover, the ethephon treatment of reproductive bougainvillea shoots increases the ACC content beyond that of the vegetative shoot. Therefore, reproductive shoots produced more ethylene than vegetative shoots, subsequently inhibiting the development of flowers or even causing serious abscission of flower buds and leaf. This reveals that the role of ethylene in regulating the flowering control of bougainvillea is bi-directional. Results of this study demonstrate the significance of shoot maturity in the growth and flowering of the bougainvillea in which ethylene plays a major role.
Potted bougainvillea ‘Taipei Red’ in four different stages of bract development were sprayed with 100-800 nL L-1 1-MCP (1-methylcyclopropene) for 4 h and were moved to low-light indoor conditions after treatment. All of the 1-MCP treatments, especially the 800 nL L-1 treatment, inhibited ethylene production and thereby significantly prolonged the longevity of the bracts during the last bract stages (stages 3 and 4). Conversely, the 1-MCP treatments did not significantly prolong the longevity of bracts at early bract stages (stages 1 and 2). Additionally, treated with 1-MCP, NAA (1-naphthaleneacetic acid), SNA (sodium salt of naphthaleneacetic acid), IBA (indolebutyric acid), BA (6-benzylaminopurine), Put (diamine putrescine), SA (Salicylic acid), or STS (silver thiosulfate) and were moved to low-light indoor conditions after treatment. Experimental results indicated that 1-MCP, NAA, SNA, BA, Put, SA prolonged bract longevity. In addition, this treatment significantly reduced endogenous ACC content and ACC oxidase activity, suggesting that the inhibition of ethylene production was achieved via physiological metabolism. However, treatment with IBA or KH2PO4 (potassium dihydrogen phosphate) had no effect on the bract longevity at any stage. In the combined chemical treatments, NAA + STS or NAA + SA were effectively for prolonging bract longevity and contained less protein or chlorophyll degradation, decrease ACC oxidase or ethylene production than the control. In conclusion, we propose that combined chemical treatment was significantly prolonged bract longevity and more effectively than single chemical treatment at any stage.
Passion fruit (Passiflora spp.) is a tropical vine crop in the family Passifloraceae. In subtropical and tropical regions, such as the lowlands of Taiwan, passion fruit is grown outdoors, often flowering during the spring and early autumn. Both the growth and flowering of the Taiwan species of passion fruit are inhibited during the winter. The aim of this research was to elucidate the means by which plant growth regulators influence the growth and flowering of passion fruit.
Potted passion fruit ‘Tai-nung No.1’ was sprayed with either silver nitrate (AgNO3) or silver thiosulfate (STS), whereupon it was moved into low temperature conditions (20/15℃). The results showed that treatment with AgNO3 (0.5, 1 mM) or STS (0.5, 1 mM) induced flower formation and formed the first flower buds in all test plants within approximately 2 weeks post treatment. This was true for all tested plants with endogenous ACC content, ACC oxidase and ethylene lower than that of the controls at 20/15℃. The control plants exhibited no flower formation at 20/15℃. Additionally, flower buds were aborted in all treatment plants which were unable to flower successfully. The results showed that following the appearance of flower buds, subjecting the plants to cold stress prevented the full development of flowers, or a reduction in resistance to stress when the plants were still young.
We then treated plants with STS or AgNO3 to induce the formation of flowers under low temperature conditions (20/15 ℃), whereupon the plants were moved to higher temperatures of 25/20℃, in which the flower buds developed well. Reducing the node of first flower bud enabled the full flowering of the buds. Additionally, the maturity of passion fruit shoots also influenced resistance to reduced temperatures. We divided the passion fruit into three stages according to the number of nodes (P1- 5-11 nodes, P2- 12-18 nodes, P3-19-25 nodes) after spraying with 1 mM STS, under low temperature conditions. The results showed that the flower buds of young plant (P1) were all aborted following injury due to chilling. Older plants (P2, P3), with more mature shoots, continued the development of flowers.
Salicylic acid (SA) inhibits the production of ethylene, thereby enhancing resistance to biotic and abiotic stress in the growth and development of plants. Variations in the pH values of SA has a significantly effect the growth of passion fruit. An SA solution of pH 6.5 promoted growth and the formation of passion fruit flowers under low temperature conditions. In contrast, treatment with an SA solution of pH 2.4 resulted in slow growth, and no formation of flower buds. The concentration of SA also influences young plants (P1, 5-11 nodes), which were prompted to form flowers by higher concentrations of SA (>2.5 mM). Old plants (P2, 12-18 nodes) with mature shoots responded only to low concentrations of SA (0.5-2.0 mM) to achieve the formation of flowers. The treatment of passion fruit with SA could help to develop flowering under low temperature conditions; however, flower buds still have a high abortion rate. On the other hand, treatment with SA to induce flower formation under low temperature conditions (20/15 ℃), followed by a shift to higher temperatures (25/20℃) leads to the development of full flowers, with a reduction in the abortion rate of flower buds.

並列關鍵字

Bougainvillea ； Passionfruit ； Ethylene ； Flowering

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