花壇用種間雜交石竹之選育

Abstract

石竹屬(Dianthus L.)植物廣泛被應用於花壇、盆花及切花。花壇石竹多不耐高溫多濕環境，而長萼瞿麥[D. longicalyx Miq. (Maxim.) Will.]等臺灣原生石竹可於霧峰地區全年開花，取其為親本進行雜交選育應具潛力。本研究以不同地區蒐集之長萼瞿麥、巴陵石竹(D. palinensis S. S. Ying)、中國石竹(D. chinensis L.)、五彩石竹(D. ×hybrida)及種間雜交石竹為材料，觀察蔗糖濃度及溫度對花粉離體發芽之影響、瞭解雜交組合之親和性、調查種間雜交後代性狀，並評估細胞膜熱穩定性。選拔優良單株並扦插繁殖，探討NAA濃度、溫度及光積值對選育營養系插穗發根之影響。 參試之石竹花粉培養於不含蔗糖之Brewbaker和Kwack培養基中發芽較低。長萼瞿麥適合添加10％蔗糖；但不同地區蒐集之長萼瞿麥對蔗糖濃度適應範圍略有差異；巴陵石竹適合添加25％蔗糖，中國石竹適合添加20％蔗糖，五彩石竹及種間雜交石竹適合添加15％-20％蔗糖。與原種相比，五彩石竹等種間雜交品種之花粉敗育率高、發芽率較低。 原種石竹花粉於15℃培養之發芽低於13.8％，參試石竹於45℃處理僅有極少花粉萌芽。長萼瞿麥及巴陵石竹於25℃有較高之花粉萌芽率；中國石竹與五彩石竹等種間雜交石竹之花粉於20℃培養之萌芽率稍高。 取長萼瞿麥、巴陵石竹、中國石竹及五彩石竹之葉圓片，經不同水浴溫度處理30 分鐘，測量電解質滲漏率並計算細胞膜相對傷害值(relative injury, RI)。結果顯示RI值隨水浴溫度上升呈S曲線，轉折中點溫度約為54℃。以54℃水浴，20-30 min處理較能區別參試石竹種/品種間之RI值。 長萼瞿麥及巴陵石竹可自交結實獲得種子，而五彩石竹自交、五彩石竹與長萼瞿麥或巴陵石竹雜交之結果率及結種率較低。長萼瞿麥與中國石竹雜交後代花色呈粉紫色、具香味，後代花瓣不具斑塊:具斑塊之分離比為3:1。以臺北蒐集之長萼瞿麥單株Ltp ×中國石竹‘Super Parfait Strawberry’及馬祖蒐集長萼瞿麥單株Lmz ×中國石竹‘Super Parfait Strawberry’之雜交後代直立，株高較矮，分枝性佳且花下節位數少。從上述兩組合中分別選出CsLtp1及CsLmz1、CsLmz2和CsLmz3四株單株進行扦插繁殖並比較性狀，結果顯示四營養系之花下節位數約11節，相對傷害值分別為4.5％、2.8％、0.4％及48.9％，CsLmz3因RI高可能不耐熱；CsLmz2因植株過高，分枝數不佳而淘汰。 CsLtp1及CsLmz1之株高較矮、分枝較多且花徑大，因此入選。將其與石竹台東一號香粉雲進行花朵性狀比較，結果顯示花朵斑塊、花瓣主要顏色及子房形狀為可區別之性狀。兩選系與中國石竹‘Super Parfait Strawberry’進行花朵性狀比較，其中花蕾形狀、花徑、花香、花冠下部側面、外裂片頂端長度、花瓣形狀、花瓣邊緣、花瓣缺刻深度、花瓣長度、花朵斑塊有無、花瓣主要顏色、子房形狀、子房表面、花柱長度及柱頭顏色等具可區別性。 CsLtp1插穗以500 ppm NAA處理有最佳的根數、根長及根乾鮮重，而CsLmz1發根較差且對NAA反應較不明顯。CsLtp1及CsLmz1插穗於日夜溫25/20℃及30/25℃處理發根較佳，高於35/30℃或低於20/15℃處理不利發根。光積值由3.2增加至11.7 mol·m-2·d-1使CsLtp1插穗發根數減少。而CsLmz1插穗在9.5 mol·m-2·d-1發根較佳，低於3.9 mol·m-2·d-1環境之扦插有徒長現象。

The genus Dianthus L. is widely used as bedding plants, potted flowering plants, or cut flowers. Bedding plant dianthus does not tolerate heat and humid environments, while Taiwan indigenous species such as D. longicalyx Miq. (Maxim.) Will. can flower all year round at Wufeng, Taichung City, and thus might serve as breeding parents for desirable characteristics. Plants of D. longicalyx were collected from various districts in Taiwan, D. palinensis S. S. Ying, D. chinensis L., D. ×hybrida and interspecific hybrids dianthus were used as plant materials. The objectives of this thesis were to 1) determine the effect of sucrose concentration and temperature on pollen germination in vitro, 2) measure the crossability between Dianthus species/cultivars, 3) select the potential hybrid progeny for bedding plants with high cell membrane thermostability (CMT) as measured with electrolyte leakage technique, and 4) propagate the selected lines by cuttings as affected by NAA concentration, temperature and daily light integral (DLI). Few pollen of the Dianthus germinated in Brewbaker and Kwack (BK) medium without sucrose. The optimum sucrose concentration in BK medium for pollen germination for D. longicalyx, D. palinensis, D. chinensis, D. ×hybrida, and interspecific hybrids dianthus was 10％, 25％, 20％, 15％-20％, and 15％-20％, respectively, while plants of D. longicalyx from various districts showed differential responses. Most pollen of D. ×hybrida and interspecific hybrids were abortive and thus exhibited low germination rate. Native Dianthus spp had low pollen germination rate at 15℃. Few pollen germinated at 45℃ for all species/cultivars tested. Highest pollen germination was recorded in 25℃ for D. longicalyx and D. palinensis, and 20℃ for D. ×hybrida and interspecific hybrids. Relative injury (RI) was calculated to assess genotypic differences in CMT for D. longicalyx, D. palinensis, D. chinensis, and D. ×hybrida by measuring the electrolyte leakage of leaf discs under different water temperatures for 30 min. The relationship between the RI value occurring in dianthus species/cultivars and treatment temperature was sigmoidal. A single temperature treatment at 54 °C for 20-30 min resulted in injury values near the midpoint of the sigmoidal response curve and showed the greatest sensitivity in detecting genotypic differences in heat tolerance. Both percentages of fruit and seed set were high when selfing D. longicalyx or D. palinensis. Selfed D. chinensis and D. ×hybrida or crossed with D. longicalyx and D. palinensis produced both low percentages of fruit and seed set. D. longicalyx × D. chinensis resulted in hybrids with lavender main color, fragrant flowers. Segregation ratio for petal color resulted in 3 pure (without macule) : 1 macule in progeny . The progeny of D. chinensis ‘Super Parfait Strawberry’ (Cs) × Taipei-selected (Ltp) or Mazu-collected D. longicalyx (Lmz) were erect, dwarf, well-branched, and produced large flowers. Following hybridization, four single plants CsLtp1, CsLmz1, CsLmz2, and CsLmz3 were selected, and vegetatively propagated for further evaluation. These four selected lines had 11 nodes below flower under 25°C, 13 h daylength conditions, with leaf disc RI values of 4.5％, 2.8％, 0.4％, and 48.9％ at 54 °C water bath for 20-30 min, respectively. Since CsLmz3 could be heat-intolerant as shown by high RI value and CsLmz2 was tall and poor-branched, these two lines were discarded thereafter. The selected lines CsLtp1 and CsLmz1 were then used for morphological comparison with a commercial, most similar cultivar Taitung No.1 Fragrance Cloud. Results show that the petal color pattern, petal main color, and shape of ovary were distinctive traits. A comparison of flower characteristics between the two selected line and their parent D. chinensis ‘Super Parfait Strawberry’ was conducted. Results revealed that shape of flower bud, flower diameter, fragrance, profile of lower corolla, length of outer lobes, shape of petal, margin of petal, depth of incisions of petal margin, length of petal, petal color pattern, petal main color, shape of ovary, surface of ovary, length of style, and color of stigma were distinct. Cuttings of CsLtp1 applied with 500 ppm NAA talc had most root number, root length, and root fresh and dry weights, while those of CsLmz1 exhibited poor rooting and did not respond well to NAA treatment. Cuttings of both lines had best rooting at 25/20℃ and 30/25℃, as compared with 35/30℃ or 20/15℃. Root number of CsLtp1 cuttings decreased as DLI increase from 3.2 to 11.7 mol·m-2·d-1. CsLmz1 cuttings had best rooting under 9.5 mol·m-2·d-1 and exhibited stretched growth under 3.9 mol·m-2·d-1 or lower DLI.