玉蘭花開花習性與花期調節之研究

The Research in Flowering Phenology and Flowering Regulation of Michelia alba DC

宋馥華(Fu-Hua Sung)

指導教授 ： 張育森

共同指導教授 ： 王淑美 ； 陳右人

國立臺灣大學/生物資源暨農學院/園藝學研究所/博士(2005年)

https://doi.org/10.6342/NTU.2005.02296

摘要

玉蘭花(Michelia alba DC.)為熱帶、亞熱帶地區重要庭園香花植物，在加工副產品方面亦甚有潛力，但迄今對其開花習性仍僅只有少量敘述性的文獻報告。目前玉蘭花在台灣面臨的最大栽培問題是如何使玉蘭花能週年穩定的供應鮮花，因玉蘭花的盛花期是夏季，冬季幾乎不開花。因此，本研究乃從內生、環境及外生因子著手，以期明瞭各種因子對玉蘭花開花的影響，作為改進現行栽培技術之基礎。以下為本研究結果：
一、玉蘭花的物候期：
經由本試驗觀察，在較溫暖的彰化田尾地區，玉蘭花枝梢一年有兩次生長高峰，分別為5月及9月，而夏季仍維持每月形成3節，伸長12公分的生長速率，同時一年可有三次花期，分別為5月、7-8月及9-10月。在較寒冷的台北，枝梢生長一年亦有兩次高峰，但為5月及7-8月，同時一年僅有兩次花期，分別為5-6月及9-10月。花芽大都由新梢基部第1-4節的腋芽形成，稍後的腋芽呈休眠狀態，不會萌發，新梢的頂端腋芽則常萌發為營養梢。花芽誘導時期大約為腋芽由葉鞘露出前一星期，花芽創始時期約為腋芽由葉鞘露出後一星期，故玉蘭花花芽是新梢生長時同時進行分化。花芽大約於四星期後便分化完成，同時可由外觀辨識之，並於兩個月後開放。

二、溫度對玉蘭花生育之影響
本試驗以二年生玉蘭花高壓苗盆栽，處以人工氣候室(phytotron)五種日/夜溫（35/30℃, 30/25℃, 25/20℃, 20/15℃和15/13℃），觀察溫度對玉蘭花枝梢生長與花芽形成之影響。試驗結果得知玉蘭花在自然日照下（11.9-13.1小時），以30/25℃處理的生育最佳，25/20℃雖然營養生長狀況與30/25℃相當，但花芽數量卻不如30/25℃，且較30/25℃晚16.5天開花。35/30℃、25/20℃與15/13℃處理都會抑制營養生長及生殖生長。玉蘭花枝梢在夜溫20℃以上時存在著一定的發育模式，即低節位的腋芽大都形成純花芽，枝梢中段的腋芽大都呈休止狀態，而高節位的腋芽則傾向形成營養芽，但夜溫在20℃以下此模式便會逐漸消失。

三、內生因子對玉蘭花開花的影響
（一） 除葉對玉蘭花生育之影響：於夏季生育遲緩期疏除老葉可促使玉蘭花61.67％的休眠枝梢於一個月內恢復生長，較對照組僅22.50％的休眠枝梢恢復生長顯著為高。疏除老葉處理之新梢枝長、節數、花芽數與到開花天數與對照組無顯著差異。疏除幼葉不僅無法使枝梢提早恢復生長，還會抑制枝梢萌發。另於冬季除葉可促使枝梢提早萌發，且不影響枝梢生長與開花表現，除去莖頂下五片葉處理還可提早產花。此結果顯示疏除成熟葉可做為玉蘭花產期調節的方法之一。
（二） 枝梢成熟度對玉蘭花生育之影響：於玉蘭花枝梢開花後（7月底）、休眠初期（8月底）及休眠末期（1月初）噴施具有增加花芽數效果之第一磷酸鉀顯示，於花後及休眠初期施用均無法顯著增加花芽數，而休眠末期施用卻可顯著抑制玉蘭花枝梢營養生長與增加花芽數。另外噴施0.5％之第一磷酸鉀較噴施2.0％之第一磷酸鉀效果佳。故玉蘭花枝梢於休眠末期達到可以形成花芽之成熟度，此時可以0.5％之第一磷酸鉀處理以增加花芽產量。
（三） 枝梢角度與花芽形成對玉蘭花生育之影響：枝梢角度可影響玉蘭花枝梢生長速率及花芽形成率，直立枝之生長速率較高，而水平枝與頃斜枝之花芽則較直立枝為多。枝梢角度對幼葉（第六葉）及花芽形成部位附近（第三葉）的影響較大，而老葉（第零葉）及初成熟葉（第五葉）則僅直立枝之每平方公分鮮重較水平枝為高。有形成花芽枝梢之幼葉每平方公分乾重較低，枝梢鮮重及乾重較沒有形成花芽者為輕，但若加上花芽重量，則兩者間無顯著差異。花芽數與第六片葉（幼葉）之葉面積成正相關，與第六片葉每平方公分鮮重與乾重及第五片葉之每平方公分鮮重與第三片葉之每平方公分乾重呈負相關，顯示花芽數越多，幼葉有越大、越輕的趨勢，而花芽形成部位之葉片乾物量越少。枝梢之枝徑、節間長及枝梢乾鮮重均與花芽數呈負相關，顯示花芽數越多，枝徑、節間長及枝梢重量會越小。
（四） 碳水化合物含量對玉蘭花生育之影響：本試驗以高液相層析儀(High Performance Liquid Chromatograph, HPLC)分析玉蘭花不同部位葉片及枝梢內之葡萄糖、果糖、蔗糖與澱粉之含量，結果顯示水平開花枝的幼葉各種可溶性糖與澱粉含量均較水平無花枝為高，但花芽所在的第三片葉片則除蔗糖外，葡萄糖、果糖及澱粉均有降低的趨勢，顯示碳水化合物為玉蘭花花芽形成及發育所必須。水平枝除蔗糖外，葡萄糖、果糖、澱粉及非結構碳水化合物含量均直立枝低，故蔗糖與玉蘭花花芽形成的關係較為密切。相關性分析顯示，第六片幼葉的蔗糖與每平方公分乾重、澱粉與鮮重間呈顯著正相關，非結構性碳水化合物含量與每平方公分乾重間有顯著負相關性，第五片及第三片成熟葉各項測值中只有第五片葉之非結構性碳水化合物含量與鮮重間有正相關性。枝梢方面各項測值僅與果糖有顯著相關性，其餘可溶性糖、澱粉及非結構性碳水化合物含量均與枝梢各項測值無相關性存在。
（五） 葉綠素計讀值（CMR）之應用：葉綠素計（SPAD-502）可測量葉色濃綠程度，其測量值與葉綠素含量呈顯著正相關，亦可與葉片氮含量與光合作用速率成正相關。本試驗採用葉綠素計測量彰化田間玉蘭花各類枝梢上之不同葉齡、不同節位葉片之葉綠素計讀值（CMR值），期能尋求CMR值、枝梢成熟度與開花之間之關係。結果顯示，玉蘭花葉片之CMR值與葉齡、葉片鮮重、乾重、每平方公分乾重及乾鮮重比成正相關。第六葉（葉齡不大於一個月之幼葉）之CMR值與每平方公分鮮重及枝梢乾鮮重呈負相關。第六葉之CMR值與蔗糖含量呈正相關，而第六、五、三片葉之CMR值與澱粉含量呈正相關，但與非結構性碳水化合物含量則呈負相關。因此測定葉片之CMR值除了可測定葉片及枝梢成熟度外，亦可間接且非破壞性得知枝梢同化物分配狀況，因而及早得知枝梢形成花芽的能力。

四、生長調節劑對玉蘭花生育之影響
（一） 生長調節劑對玉蘭花生育之影響：以不同濃度之naphthylacetic acid (NAA)及sodium naphthaleneacetate (SNA)噴施玉蘭花，結果顯示，SNA 50ppm與NAA 100 ppm 以上之濃度即會抑制玉蘭花芽體生長，且抑制程度會隨濃度增加而增加，高濃度甚至會使玉蘭花枝梢夭折，然SNA 50ppm與NAA 100ppm處理在抑制力消失後，新生枝梢則可產生大量的花芽。低濃度的NAA處理不會抑制玉蘭花營養生長，亦不會增加花芽數量，而NAA 20ppm有促進芽體萌發的效果。NAA及SNA促進枝梢萌發的效果在冬季低溫期無法顯現。另外，枝梢處理後到萌發天數與花芽數及葉片葉綠素計讀值（Chlorophyll Meter Reading (CMR) values)呈顯著正相關，顯示枝梢休眠越久，葉色越濃綠且花芽數量越多。而老葉CMR值與新梢花芽數間亦呈正相關，因而可能可由老葉CMR值判斷枝梢養分蓄積的程度。
Gibberellic acid3 (GA3) 150 ppm以上才有顯著提早玉蘭花枝梢萌發的效果，而200ppm以下之濃度對枝長及節數無顯著影響。除25ppm與75ppm處理之花芽數與對照組無顯著差異外，其餘處理的花芽數均較對照組為少。而到第一朵花開花天數則除了200 ppm較對照組快8.3天與175ppm較對照組慢12天外，其餘處理與對照組相比無顯著差異。而各處理之第三片葉初萌一星期時CMR值則是除25 ppm與175 ppm與對照組無顯著差異外，其餘處理CMR值均較對照組小。
在不同季節噴施GA3、Paclobutrazol (PP-333)、SNA（或NAA）、ethephon、Benzylaminopurine (BA)(或6-(benzylamino)-9(2- tetrahydropyranyl)-9H-purine (PBA)）等生長調節劑與Sliver-thiosulphate (STS)及第一磷酸鉀(KH2PO4)在玉蘭花葉片上，結果顯示，在秋季玉蘭花進入生育停頓期進行噴施，僅500 ppm之GA3有促進芽體生長之效果。噴施100 ppm 之Ethephon會造成玉蘭花落葉，並促進潛伏芽體萌發，但兩者對開花均無影響。在冬末第一次梢萌發前噴施植物生長調節劑，500 ppm 之GA3及1000 ppm 之BA可促進芽體萌發，但會抑制開花，而0.5%之第一磷酸鉀則會抑制營養生長，但可增加花朵數。而在初夏第二次生長期前噴施各生長調節劑，亦是以350 ppm 之GA3有促進芽體生長的效果，150 ppm之Ethephon亦會造成落葉並促進潛伏芽體萌發，200 ppm 之NAA則會抑制芽體萌發。除GA3與NAA外, 其餘藥劑對玉蘭花枝梢生長均無影響。在開花方面，噴施350 ppm 之GA3及15 ppm 之Ethephon之枝梢所產生的腋芽若有萌發，全都發育成營養芽。噴施300 ppm 之PP-333可產生較多的花芽，150 ppm 之Ethephon 和0.5％之KH2PO4則可使玉蘭花偏向生殖生長。200 ppm 之NAA 處理雖初期會抑制芽體萌發，但後期芽體萌發後亦可產生許多花芽。田間試驗亦與台北簡易塑膠溫室內之趨勢一致，但差異並不顯著。
（二） 生長調節劑組合對玉蘭花生育之影響：生長調節劑組合第一次盆栽試驗結果顯示第一次處理為350 ppm gibberellic acid3 (GA3)可顯著提高枝梢萌發率、枝梢生長及縮短到第一朵花開花天數，而200 ppm ethephon處理之無法提早使枝梢萌發，但可產生最多的純花芽。第二次試驗結果顯示第一次處理為20 ppm naphthylacetic acid (NAA)及第二次處理為0.5% 第一磷酸鉀(KH2PO4)者會延後枝梢萌發，第二次藥劑處理為10 ppm 6-(benzylamino)- 9(2-tetrahydropyranyl)-9H-purine (PBA)者會降低花芽數量。兩次試驗均顯示第一次處理為GA3及第二次處理為PBA者最強的營養生長勢及較多的腋芽發育為營養芽。彰化田間試驗則第一次處理為除葉者可顯著提高枝梢萌發率，GA3雖無提高枝梢萌發率，但枝長與節數顯著較對照組為高。腋芽發育方面則無顯著性差異。
綜上所述，玉蘭花開花深受溫度、內生因子如枝梢角度及枝梢成熟度等影響，生長調節劑，碳水化合物亦扮演重要的角色。欲使玉蘭花於冬季低溫期開花，除需有成熟度夠的枝梢，以生長調節劑組合來促使玉蘭花冬季產花的方法應屬可行，惟藥劑處理時間間隔及田間應用的濃度還需更多測試，才能應用於實際生產上。

關鍵字

玉蘭花 ； 花期調節 ； 開花習性

並列摘要

Michelia alba DC. is a fragrant flowering plant which is wildly grown in tropical and subtropical gardens. Besides using as cut flowers, fragrant flowers also can use as a processing material. However, there are only a few papers that described its flowering phenology till now. The biggest problem on M. alba flower production in Taiwan is to maintain year-round production. The main flowering period of M. alba is in summer and there is almost no flower produce in winter. The aims of this research were to understand how the environmental, interior, and exterior factors affect the flowering of M. alba and to estabilish the basic flowering information for commercial flower regulation. Following are the results:
I. The flowering phenology of M. alba.
There are 3 flowering times of M. alba in Chang-Hua (warmer place) within a year, whereas, plants in Taipei (colder place) only have two flowering times. Flower buds always form at the base of shoots (1-4 nodes) and vegetative buds form at top of shoots. The axillary buds located at middle part of shoots are often tended to become unsprouted buds. The time of flower induction was 1 week before the axillary bud uncovered from apical bud shell and flower initiation was 1 week after the axillary bud uncovered from apical bud shell. All floral organs finished differentiation about 4 weeks after the axillary bud uncovered from apical bud shell. Bloom occurred 2 month after the flower bud induction.

II. Effects of temperature on shoot growth and flowering in M. alba.
The effects of temperature on shoot growth and flower bud formation of three-year-old air-layering M. alba plants were studied. Plant grown in glass growth room with day/night temperatures of 35/30℃, 30/25℃, 25/20℃, 20/15℃ and 15/13℃ and with natural daylength(11.9 to 13.1 hours). Plants at 30/25℃ had the greatest growth and flowering. Although shoot growth of plants at 25/20℃ was not significantly different from plants at 30/25℃, flowering at 25/20℃ was 16.5 days later than at 30/25℃. Growth and flowering were inhibited at 35/30℃,20/15℃ and 15/13℃. When night temperatures were above 20℃, axillary buds located at the base of the shoot developed into flower buds, and vegetative buds formed at the top of the shoot. Growth of axillary buds in the middle part of the shoot tended to stop growing. The phenomenon disappeared at night temperatures below 20℃. To sum up, temperature is one of main factors of shoot growth and flowering in M. alba, and the optimum temperature range for shoot growth and flowering are 30-20℃ and 30-25℃ respectively.

III. Effects of interior factors on shoot growth and flowering in M. alba.
1. Effects of removing leaves on shoot growth and flowering in M. alba: removing old leaves when plants grew slowly in summer could promote 61.67% of dormant shoots recover growing within 1 month and the ratio was significantly higher than that of control, 22.50%. Removing old leaves did not affect the length, node number, flower bud number and days to first bloom of new shoots. Removing young leaves could not promote shoot to sprout, it would inhibit the new shoots growth, either. Although removing leaves in winter could not make shoots sprout immediately, but those shoots did sprout earlier than control in spring. The growth and flowering of shoots that were removed leaves were not affected by removing leaves and removed 5 leaves under apical bud could decrease the days to first bloom. Those results showed that removing leaves could be a method of flowering regulation in M. alba.
2. Effects of shoot maturity on shoot growth and flowering in M. alba: spraying KH2PO4 on the shoots after flowering (July), at the onset of dormancy (August), and at the end of dormancy (January) to investigate the effects of shoot maturity on flowering. Only when KH2PO4 applied to shoots at the end of dormancy could increase flower bud number and inhibit shoot growth. The effects of 0.5% KH2PO4 was better than that of 2.0%.
3. Effects of shoot angle from horizontal and flower bud formation on shoot growth and flowering in M. alba: shoot angles could affect the growth rate and the ratio of flower bud formation of the shoots. Vertical shoots (80-90°) grew faster than horizontal (0-15°) shoots, but horizontal and sloppy (40-50°)shoots had more flower buds. The fresh weight (FW) and dry weight (DW) of young leaves (the sixth leaf) and the leaves near flower buds would be affected by shoot angle, whereas only specific fresh weight (SFW) of old leaves (the zero leaf) and just mature leaves (the fifth leaf) on vertical shoots would be heavier than those of on horizontal shoots. If flower bud formed on shoots, the specific dry weight (SDW) of young leaves and shoot FW, DW were lighter than shoots without flower buds. Flower number on shoot was negative correlated with SFW and SDW of young leaves (the sixth leaf), the SDW of the leaves near flower buds (the third leaf) and internode length, FW and DW of stems.
4. Effects of carbohydrate content on shoot growth and flowering in M. alba: the soluble sugars, starch and non-structural carbohydrate content in leaves and stem of M. alba were determined by using High Performance Liquid Chromatograph (HPLC). The glucose, fructose, starch, and non-structural carbohydrate contents in leaves and stems of vertical shoots were higher than those of horizontal shoots. On the contrary, sucrose content was higher in leaves and stems of horizontal shoots than that of vertical shoots. Horizontal shoots with flower buds had more soluble sugars and starch than horizontal shoots without flower buds. The soluble sugars and starch contents decreased in the leaves near flower buds (the third leaf). These results indicate the carbohydrates are important for flower bud formation. The sucrose content was positive correlated with specific dry weight of young leaves and non-structural carbohydrate content of fifth leaf was negative correlated with fresh weight of leaves. The length, fresh weight and dry weight of stems were positive correlated with fructose.
5. The application of Chlorophyll Meter Reading (CMR) values: the green extent of leaves of M. alba grown in Chang-Hua field were determined by using a chlorophyll meter (SPAD-502). The age, fresh weight (FW), dry weight (DW), specific dry weight (SDW) and dry/fresh weight ratio (D/F) were positive correlated with CMR values of leaves. The specific fresh weight (SFW), FW and DW of stems were negative correlated with CMR values of young leaves (the sixth leaf). The CMR value of the sixth leaf was positive correlated with sucrose content. Starch content in all leaves was positive correlated with CMR value, whereas there was negative correlation between non-structural carbohydrate content and CMR values of all leaves. Hence, the FW and DW of leaves and shoots and the carbohydrate contents of leaves might be detected by using the Chlorophyll Meter Reading.

IV. Effects of plant growth regulators on shoot growth and flowering in M. alba
甲、 Effects of applying plant growth regulators on shoot growth and flowering in M. alba: applying naphthylacetic acid (NAA) and sodium naphthaleneacetate (SNA) on M. alba. SNA 50ppm and NAA 100 ppm inhibited shoot growth, and the higher the concentration, the more inhibition would have. However, when the inhibition of SNA 50ppm and NAA 100ppm disappeared, new shoots produced more flower buds. Lower concentration of NAA would not inhibit shoot growth, but it would not increase flower buds, either. NAA 20ppm might promote shoot sprouting, however both NAA and SNA could not promote shoot sprouting in winter. In addition, days to shoot sprouting and flower number were positive correlated with Chlorophyll Meter Reading (CMR) values of old leaves. This indicated that the longer the shoots kept in dormancy, the more green extent of leaves and flower buds were. Hence, the nutrient condition of shoots might be detected by using CMR values.
Gibberellic acid3 (GA3) 150 ppm promoted shoot sprouting in M. alba, and the GA3 concentration under 200 ppm would not affect the shoot length and node number. Besides 25 ppm and 75 ppm GA3 treatments would not affect flower bud number, GA3 concentration above 75 ppm would decrease flower bud. First flower of GA3 200 ppm treatment could bloom 8.3 days earlier than control. Besides CMR values of 25 ppm and 175 ppm GA3 treatment, other concentration treatments would decrease CMR values.
Applying GA3, Paclobutrazol (PP-333), SNA (or NAA), ethephon, Sliver-thiosulphate (STS), Benzylaminopurine (BA) (or 6-(benzylamino)-9(2–tetrahydropyranyl)-9H-purine (PBA)) and KH2PO4 on leaves of M. alba in different seasons to investigate the effects of plant growth regulators (PGRs) on shoot growth and flowering in M. alba. Only 500 ppm GA3 treatment could promote shoot sprouting and 100 ppm Ethephon would cause leaves to drop and promote buds to sprout when applied at the time when shoots ceased growth in autumn. However, both PGRs did not affect flowering. At the end of winter, applied 500 ppm GA3 and 1000 ppm BA could promote bud sprouting, but these PGRs would inhibit flower bud formation. Applied 0.5% KH2PO4 could inhibit shoots growing and increase flower bud number. When the shoots were going to enter dormancy in summer, applying 350 ppm GA3 could promote shoots to sprout, 150 ppm Ethephon could make leaves drop and promote buds to sprout, and 200 ppm NAA would inhibit shoots to sprout. Besides GA3 and NAA treatment, other PGRs did not affect shoot growth. In addition, when plants were treated with 350 ppm GA3 and 15 ppm Ethephon, axillary buds on new shoots almost developed into vegetative buds, whereas 300 ppm PP-333, 150 ppm Ethephon and 0.5％ KH2PO4 treatment could make the axillary buds on new shoots developed into flower buds. Although 200 ppm NAA treatment would inhibit shoots to sprout, but when the inhibition disappeared, the axillary buds on new shoot could form more flower buds. The results of field experiment in Chang-Hua were similar as the results that conducted in the plastic greenhouse in Taipei, but the differences between PGR treatment and control were more minified.
2. Effects of applying plant growth regulators combination on shoot growth and flowering in M. alba: when the first plant growth regulator treatment was applied 350 ppm gibberellic acid3 (GA3), shoot sprouting ratio and shoot growth could be increased and days to first bloom could be reduced. 200 ppm ethephon as the first PGR treatment chemical could produce more flower buds. 20 ppm naphthylacetic acid (NAA) as the first PGR treatment chemical and 0.5% KH2PO4 as the second PGR treatment chemical would delay shoot sprouting. 10 ppm 6-(benzylamino)- 9(2-tetrahydropyranyl)- 9H-purine (PBA) as the second PGR treatment chemical would reduce flower buds. GA3+PBA combination made shoots grow vigorous and the axillary buds on new shoots always developed into vegetative buds. In the field experiment in Chang-Hua, removed leaves could promote shoot sprouting. GA3 treatment made shoots longer than that of control, but did not promote shoot sprouting. All combination treatments did not affect the development of axillary buds on new shoots.
To sum up, flowering of M. alba was affected by temperatures, interior factors such as shoot angle, shoot maturity, carbohydrates etc. and plant growth regulators (PGRs). In order to regulate M. Alba bloom in winter, PGRs combination should be a useful method to achieve this goal. However, before using on commercial production, more experiments should be conducted to know the correct time of application, applied concentration in the field, and so on.

並列關鍵字

Michelia alba ； Flowering Regulation ； Flowering Phenology

參考文獻

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吳淑均 1995. 溫度、遮陰、生長調節劑及修剪時期對仙丹花生長與開花的影響. 國立台灣大學園藝學研究所碩士論文.