重瓣及香氣孤挺花品種之選育

Abstract

孤挺花可供盆植、切花或景觀應用，市場需重瓣具香氣品種。本論文收集41個單瓣品種與33個重瓣品種，進行品種性狀、重瓣特性及花粉發芽之研究。結果顯示單瓣品種花之器官由外而內依序分別為萼片、花瓣、雄蕊和雌蕊，共四輪。重瓣品種之花器數目及排列，大致可分為二大類，類型一為花朵器官排列仍為四輪，基本輪數不變，僅雌、雄蕊瓣化程度差異；類型二為花器官輪數增加，各增加一輪雌、雄蕊，增加之雌或雄蕊瓣化、部分瓣化或無瓣化。其中類型一又可依雌雄蕊瓣化程度細分成三群，類型二增加輪數後所有雌雄蕊又因瓣化程度差異可細分為五群。 以根尖染色體之壓片觀察，探討孤挺花商業品種之染色體數與倍體數，結果顯示Montevedio、Papillio Butterfly及Estella等品種染色體為2n = 22條，為二倍體；Gervase、Fortune及Blossom Peacock等品種之染色體為2n = 44條，為四倍體。測量19個商業品種之DNA含量，其中6個二倍體品種之染色體DNA含量在38.72 - 49.47 pg，13個四倍體品種之染色體DNA含量在71.35 - 94.04 pg。 由六個重瓣孤挺花品種之不同類型花藥取下花粉，以含10%蔗糖B&K培養基、於28oC培養2小時，結果顯示正常花藥、畸形花藥及雄蕊瓣化殘存花藥之花粉皆可發芽。除 ‘Splash’瓣化花藥產生之花粉發芽率較低外，其他五個參試重瓣孤挺花之花粉發芽率皆大於50%。 ‘Blossom Peacock’正常花藥之花粉發芽適溫在25-35oC，各類型花藥產生之花粉皆在培養後2小時達最大發芽率，約78%-91%。‘Blossom Peacock’三種類型花藥產生之花粉與單瓣‘Design’雜交，結果顯示授粉30天後皆可收穫種子，花粉來源對每果實種子數及種子發芽率無顯著影響。 觀察65個雜交組合之後代，共3936植株，嘗試以雜交一代之後裔單瓣與重瓣株數，進行重瓣遺傳之推論。以一雙基因顯性表現重瓣並受隱性修飾基因調節之模式評估後代是否符合假說，結果有45組雜交組合後代分離比符合1重瓣: 3單瓣(χ2 = 0.00-7.68)，16組雜交組合後代分離比符合3重瓣: 5單瓣(χ2 = 0.04-7.48)，1組雜交組合後代分離比符合1重瓣：1單瓣(χ2 = 0.00)。 為選育出具香氣的孤挺花新品種，以香氣濃郁之孤挺花二倍體品種與具香氣之四倍體品種進行雜交育種。於授粉後7、10、14天採收各雜交組合果莢，取胚珠培養於1/4MS培養基鹽類濃度並添加15 g·L-1 sucrose，結果顯示以授粉後14天採收者萌芽率較高。以二倍體‘Estella’為種子親與 四倍體‘Trendsetter’雜交之胚珠萌芽率少於18.2%，以四倍體品種為種子親之雜交胚珠萌芽率顯著較高。以‘Estella’與四倍體‘Faro’、‘Trendsetter’及‘Christmas Star’雜交，獲得14株雜交後裔，以流式細胞儀分析基因組含量，結果顯示12株雜交後裔為三倍體，2株雜交後裔為四倍體。以氣象層析儀-質譜儀分析雜交後裔單株花朵香氣化學成分，後裔同時具有兩親本之香氣成分。 為選育出花莖長、紅色、重瓣且具香氣之孤挺花新品種，以單瓣‘San Remo’與重瓣‘Blossom Peacock’為親本進行雜交，選拔出重瓣‘種苗1號-粉珍珠’；為選育出紅色、重瓣且具香氣之孤挺花盆花新品種，以單瓣‘Design’與重瓣‘Blossom Peacock’為親本進行雜交，選拔出重瓣‘種苗2號-紅豔’，並已獲得植物品種權。

Amaryllis (Hippeastrum hybridum Hort.) is used in many areas for potted or cut flowers and landscaping. Double-flowered and fragrant cultivars are desirable. We collected 41 single- and 35 double-flowered cultivars for morphological observation. Flowers of single-flowered amaryllis consist of three sepals, three petals, six stamens, and one tri-carpel-united pistil from outer towards inner. Double-flowered cultivars could be classified into two major types. Flowers of type I double-flowered cultivars consist of four organ whorls and further three sub-types could be divided based on degree of petalization. Flowers of type II cultivars had additional whorls of stamen and carpel, and five sub-types could be divided based on degree of petalization. Mitotic metaphase chromosomes were prepared from root tips. Results show that 2n=22 chromosomes for ‘Montevedio’, ‘Papillio Butterfly’, and ‘Estella’, while 2n=44 for ‘Gervase’, ‘Fortune’, and ‘Blossome Peacock’. Flow cytometric comparison of ploidy in 19 cultivars, revealed that 6 cultivars were diploid and had DNA contents of 38.72-49.47, as compared to 13 cultivars were tetraploid, with DNA contents of 71.35-94.94 pg. Pollen from normal, defected, and tepalized anthers of six amaryllis cultivars were incubated in B&K medium containing 10% sucrose at 28oC for 2 h. Pollen all germinated, with 50% or higher germination rate, except for tepalized anthers of ‘Splash’. Optimum temperatures for pollen from normal anthers of ‘Blossom Peacock’ ranged from 25 to 35oC. Pollen from three types of anthers in ‘Blossom Peacock’ germinated at 2 h after culture, with 78%-91% germination. Pollen source did not alter fruit set number of hybrid seeds per fruit, and seed germination rate when placed the pollen onto the stigma of ‘Design’. A total of 3936 progenies were created from 65 cross combinations and from the number of single-flowered and double-flowered progenies tried to deduce the inheritance of double-flowered. A model consists of two dominant genes expressed in the heterozygous or homozygous state causing double-flowered phenotype and modified by a recessive locus was proposed. Progenies of 45 cross combination segregated into 1 double : 3 single ratio (χ2 = 0.00-7.68), 16 cross combinations segregated into 3 double : 5 single (χ2 = 0.04-7.48) and 1 cross combination segregated into 1 double : 1 single (χ2 = 0). Since progeny of two fragrant parents are usually fragrant, we selected diploid and tetraploid parents cultivars both have fragrant flowers. The hybrid ovules were collected and cultured in 1/4MS with 15 g·L-1 sucrose medium. The ovules at 14 days after pollination (DAP) had higher germination than those at 7 or 10 DAP. Ovule germination was lower than 18.2% in diploid than tetraploid cultivars as seed parents. Fourteen hybrid progenies were obtained after crossing diploid ‘Estella’ and tetraploid ‘Faro’, ‘Trendsetter’, and ‘Christmas Star’. Flow cytometry revealed that 12 progenies were triploids, and 2 were tetraploids. GC-MS analysis showed that hybrid individuals had fragrant compounds of both parents. Single-flowered ‘San Remo’ was used as seed parent and crossed with double-flowered ‘Blossom Peacock’. A red double-flowered progeny was selected for cut flowers and named as ‘T.S.S. No.1-Pink Pearl’. Single-flowered ‘Design’ was used as seed parent and crossed with ‘Blossom Peacock’. A red double-flowered progeny was selected for potted plants and named as ‘T.S.S. No.2- Red Splendor’. Both cultivars have been granted with plant breeder’s right.