洋桔梗育種強調花型及花色，解析其遺傳機制有助於提升育種效率。本研究選臺南區農業改良場自交4-6世代之洋桔梗純系，調查其F1之花朵性狀。結果顯示不論親本花徑為何，F1花徑皆為中輪(5.1-5.9 cm)或大輪花(≧6.0 cm)，F1花徑均≥親本花徑。重瓣×重瓣、重瓣×單瓣或單瓣×重瓣之雜交組合均為重瓣，推測重瓣係由一個完全顯性之基因控制(D’)。將紅、藍、紫或粉紅花色等具花青素之品系相互雜交，其F1均為具花青素之花色。取花瓣具花青素×不具花青素(白或黃綠花色)或不具花青素×花青素等親本相互雜交，其F1花瓣均具花青素。單一花色之雜交F1均為純色。覆輪花色×覆輪花色、覆輪花色×單一花色或單一花色×覆輪花色之雜交組合多為覆輪花色，有些外觀為純白花品系可能具覆輪基因。白花與黃綠花色品系雜交組合之F1均為黃綠色。本研究參試之洋桔梗花瓣累積色素之顏色顯性關係大致為紫>粉紅>白。

A better understanding of the inheritance of flower form and color in lisianthus [Eustoma grandiflorum (Raf.) Shinn.] would facilitate breeding efficiency. This study investigated the flower traits of F1 hybrids from crossing several pure lines, which were selfed 4-6 generations at Tainan District Agricultural Research and Extension Station, Taiwan. Results showed that flower diameter of the F1 ranged from medium (5.1-5.9 cm) to large (≧6.0 cm) sizes, which were equal to or larger than parental flower diameter. All F1 hybrids from crosses between double-flowered lines and reciprocal crosses between double- and single-flowered lines produced double flowers. F1 hybrids produced flowers with anthocyanins, provided that flowers of one or both parents had anthocyanins. F1 from crosses between single-colored lines produced single-colored flowers. Although some lines with pure white flowers may carry picotee genes, all F1 produced picotee flowers when one or both parents had picotee flowers. F1 from crossing white and yellowish-green flower lines produced yellowish-green flowers. The order of dominance of pigment color on flowers generally behaved as purple > pink > white.