朱蕉之開花誘導及雜交誘變育種

Flowering Induction, Hybridization and Mutation Breeding of Cordyline

吳宗憲(Tsung-Hsien Wu)

指導教授 ： 葉德銘

國立臺灣大學/生物資源暨農學院/園藝學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.02161

摘要

朱蕉[Cordyline fruticosa (L.) A. Chev.] (= C. terminalis Kunth)為龍舌蘭科(Agavaceae)常綠灌木，對光強度適應性廣、耐旱、葉色和葉形多變化，可廣泛應用於熱帶與亞熱帶地區之景觀植栽及室內綠美化，被譽為熱帶觀葉植物之王。臺灣之氣候環境適宜栽培朱蕉，但目前自有品種少、雜交育種或誘變之技術仍不清楚，亟待建立朱蕉育種之相關技術。
朱蕉自交不親和，又花期短、品種間花期不一致，需調節花期以利雜交授粉。參試朱蕉品種之開花率隨處理激勃酸濃度由2500 - 5000 mg•L-1增加而上升，但於不同季節和品種間處理之開花表現不同，於4月時對火焰朱蕉(‘Chocolate’)、錦葉朱蕉(‘Fire Fountain’)、檸檬綠朱蕉(‘Lemon Lime’)、大葉紅邊朱蕉(‘Plumdinger’)、亮葉朱蕉(‘Red Sister’)、白馬朱蕉(‘White Edge’)、暗紅朱蕉(‘Cooperi’)、紅白馬朱蕉(‘John Klass’)、翡翠朱蕉(‘Kiwi’)、咖啡公主朱蕉(‘Tartan’)、艷紅朱蕉(‘Thelma’)、喀麥隆朱蕉(‘Cameroon’)、彩葉娃娃朱蕉(‘Cointreau’)、娃娃朱蕉(‘Dolly’)、巧克力朱蕉(‘Miss Andrea’)、月光朱蕉(‘Moonlight’)、彩虹朱蕉(‘Amanda’s Blush’)、夏威夷小朱蕉(‘Baby Ti’)、細葉朱蕉(‘Bella’)、密葉朱蕉(‘Hawaiian Compacta’)和錦翠朱蕉(‘Youmeninshiki’)噴施5000 mg•L-1 GA3於心部葉片至產生逕流，可誘導植株於6月時開花，但其中僅有火焰朱蕉、錦葉朱蕉、檸檬綠朱蕉、大葉紅邊朱蕉、亮葉朱蕉和白馬朱蕉之花藥呈鮮黃色飽滿狀，具鮮黃色之花粉，其他品種之花藥則呈灰白色乾癟狀，無花粉產生，僅可作為種子親。於9月時對火焰朱蕉、錦葉朱蕉、檸檬綠朱蕉、大葉紅邊朱蕉、亮葉朱蕉、白馬朱蕉、暗紅朱蕉、紅白馬朱蕉、翡翠朱蕉、咖啡公主朱蕉、艷紅朱蕉、暗紅朱蕉、紅白馬朱蕉、翡翠朱蕉、咖啡公主朱蕉、艷紅朱蕉、彩葉朱蕉(‘Tricolor’)、‘Peter Buck’、喀麥隆朱蕉、彩葉娃娃朱蕉、娃娃朱蕉、巧克力朱蕉和月光朱蕉噴施5000 mg•L-1 GA3於心部葉片至產生逕流，可誘導植株於11月時開花，但喀麥隆朱蕉、彩葉娃娃朱蕉、娃娃朱蕉、巧克力朱蕉和月光朱蕉無花粉產生，僅可作為種子親，其他品種具鮮黃色之花粉，可作為花粉親與種子親。
探討朱蕉之花粉特性，可提高雜交授粉成功率。冬季自然開花之白馬朱蕉與亮葉朱蕉花粉培養於添加0% - 20%蔗糖之B&K培養基，結果以15%蔗糖處理者之花粉萌發率較高。以含15%蔗糖之B&K培養基培養彩葉朱蕉開花當天之花粉，萌發率可接近100%，開花前、後一天之花粉則幾乎不萌發，故應取開花當天之花粉進行授粉之效果較佳。取白馬朱蕉與錦葉朱蕉開花當天之花粉於相對濕度50%下冷藏於4℃，6天後其花粉體外萌發率仍為30%以上，花粉約可儲藏一週。將亮葉朱蕉自交後進行體內花粉管生長觀察，可見其花粉可萌發花粉管於花柱內生長，但生長至花柱底端即停止，並未進入子房，表示朱蕉具配子體型自交不親和現象。
朱蕉具硬厚之種皮，自然狀況下種子發芽率低、發芽天數長且種子發芽不整齊，以TTC法檢測白馬朱蕉×錦葉朱蕉之種子，皆可染色，具活力。白馬朱蕉×錦葉朱蕉種子以砂紙磨破種皮後，發芽率較高且播種到發芽天數較短；大葉紅邊朱蕉×咖啡公主朱蕉種子經磨破種皮與去除種皮處理之發芽率與發芽天數無顯著差異。綠葉朱蕉種子浸泡於濃硫酸中5 – 40 min，無法縮短朱蕉種子到發芽天數，且浸泡20 min後，種子發芽率降低。錦葉朱蕉×白馬朱蕉種子刻傷後浸泡於0 - 200 mg•L-1 GA3中12 h，結果發芽率無顯著差異，以刻傷後浸泡100 mg•L-1 GA3處理者之發芽天數顯著較對照組短，其他處理間無顯著差異。錦葉朱蕉×白馬朱蕉種子經冷水浸種10、20天無法促進發芽；浸種於70℃溫湯5 min以上與35℃乾燥處理16天後其種子皆無法發芽；照光與否對其種子發芽之影響不顯著；全果播種之種子發芽率較低。朱蕉種子播種於不同日/夜溫下，結果到發芽天數與每日均溫呈直線負相關，隨溫度提高為35/30℃，到發芽天數較短。
白馬朱蕉栽培於日/夜溫35/30、30/25、25/20、20/15℃，結果以30/25℃處理之葉片生長與葉斑表現均較佳。
誘變處理以產生變異品種，可縮短朱蕉之育種年限。夏威夷小朱蕉莖段插穗之存活率與處理γ射線劑量由0 – 150 Gy呈直線負相關，半致死劑量(lethal dose at 50%, LD50)為102 Gy，並產生葉斑變異株。娃娃朱蕉莖段與側芽插穗之生長量皆與處理劑量呈直線負相關，其LD50約為165 Gy。
本研究由雜交育種共獲得朱蕉品種間雜交組合共35個、9109粒種子，待植株性狀表現穩定後，將評估其成為新品種之潛力，期望可選拔出朱蕉新品系供景觀及室內綠美化使用。

關鍵字

龍舌蘭科 ； 開花調節 ； 觀葉植物 ； 花粉培養 ； 種子發芽 ； γ射線

並列摘要

Cordyline [Cordyline fruticosa (L.) A. Chev.] (= C. terminalis Kunth) is an Agavaceae evergreen shrub. With variations in leaf shape and color, drought tolerant, and a wide range of light intensity tolerance, Cordyline is know as the king of tropical foliage plants, and is widely used as landscape and indoor plants in the tropical and subtropical areas. Climate in Taiwan is suitable for growing and breeding cordyline. However, limited cordyline cultivars have been developed in Taiwan and the hybridization technique is little known. The objects of this thesis were to establish the hybridization protocols for cordyline.
Flowering regulation is crucial for hybridization since cordylines are self-sterile and had short flowering durations and various flowering time, depending on cultivars. Results showed that the flowering rate of 7 cordyline cultivars increased with increasing gibberellic acid concentration from 0 to 5000 mg•L-1. The effect of GA3 treatment on flowering varied across different seasons and cultivars. A spray of 5000 mg•L-1 GA3 on top leaves until run-off in April induced plants to flower in June in ‘Chocolate’, ‘Fire Fountain’, ‘Lemon Lime’, ‘Plumdinger’, ‘Red Sister’, ‘White Edge’, ‘Cooperi’, ‘John Klass’, ‘Kiwi’, ‘Tartan’, ‘Thelma’, ‘Cameroon’, ‘Cointreau’, ‘Dolly’, ‘Miss Andrea’, ‘Moonlight’, ‘Amanda’s Blush’, ‘Baby Ti’, ‘Bella’, ‘Hawaiian Compacta’, and ‘Youmeninshiki’. However, only the first six cultivars produced flowers with yellow anthers containing yellow pollen after treatment, whereas the other cultivars produced flowers but had grey, shrivelled anthers without pollen. A spray of 5000 mg•L-1 GA3 on top leaves until run-off in September induced plants to flower in November in ‘Chocolate’, ‘Fire Fountain’, ‘Lemon Lime’, ‘Plumdinger’, ‘Red Sister’, ‘White Edge’, ‘Cooperi’, ‘John Klass’, ‘Kiwi’, ‘Tartan’, ‘Thelma’, ‘Tricolor’, ‘Peter Buck’, ‘Cameroon’, ‘Cointreau’, ‘Dolly’, ‘Miss Andrea’, and ‘Moonlight’. However, no pollen was produced in ‘Cameroon’, ‘Cointreau’, ‘Dolly’, ‘Miss Andrea’, and ‘Moonlight’.
Pollen of ’White Edge’ and ‘Red Sister’ obtained from natural flowering in winter was cultured on B&K medium containing 0%-20% sucrose. Highest pollen germination rate was obtained in medium with 15% sucrose. Nearly all pollen of ‘Tricolor’ collected at anthesis germinated, while pollen collected 1 day before or after anthesis almost failed to germinate. ‘White Edge’ and ‘Fire Fountain’ pollen collected at anthesis and stored at 4oC for 6 days remained with 30% or higher germination rates, indicating that cordyline pollen could be stored up to one week. Tissue section was performed on self-pollinated flowers of ‘Red Sister’ to observe pollination behavior. Results showed that the pollen germinated and pollen tubes reached the base of the style but not the ovary, indicating gametophytic incompatibility in cordyline.
Seeds of cordyline had tough seed coats. Natural seeds had low germination rates, and incongruent and long germination time, although the seeds were viable as shown with TTC method. Scarificated cordyline seeds increased germination rate and reduced germination time. Germination rate and time to germination did not differ between mechanical scarification and seed coat removal treatments. Chemical scarification with concentrated sulfuric acid did not reduce time to germination, but reduced germination rate after soaking for 20 minutes or longer. Soaking scarified seeds in 0 - 200 mg•L-1 GA3 for 12 h did not affect germination rates, while 100 mg•L-1 GA3 treatment resulted in shorter time to germination, as compared with control. Soaking seeds in 25 oC water for 10 and 20 days did not affect the germination of cordyline seeds. Germination was inhibited by hot water immersion treatment at 70oC for 5 min or longer. Seeds treated with dry heat at 35oC for 16 days failed to germinate. Light and dark treatments did not affect germination of cordyline seeds. Seeds sown with the fruit intacted had reduced germination rate. As mean daily temperature increased from 14.0 oC to 32.5 oC, time to germination decreased linearly.
Cordyline ‘White Edge’ were cultured under day/night temperature 35/30, 30/25, 25/20, and 20/15. Best leaf growth and leaf variegation was obtained in 30/25℃.
As γ radiation dose increased from 0 to 150 Gy, survival rate of ‘Baby Ti’ stem segment cuttings decreased linearly, with LD50 of 21 Gy. As γ radiation dose increased from 0 to 250 Gy, survival rate of stem segment cuttings and lateral shoot cuttings of ‘Dolly’ decreased linearly, with LD50 of 165 Gy.
Thirty-five Cordyline cross combination, more than 9000 seeds, were obtained in this thesis. Different hybrids will be evaluated for their suitability as pot plant or landscaping material in terms of plant size, leaf shape, and colors.

並列關鍵字

Agavaceae ； flowering regulation ； foliage plant ； pollen culture ； seed germination ； γ-ray

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