喜蔭花之葉斑及花色遺傳、栽培與耐低溫選育

Abstract

喜蔭花屬(Episcia)植物因豐富之葉片性狀與花色及耐低光性，而可做為室內開花之觀葉植物。然而，關於喜蔭花屬植物之栽培及遺傳相關研究甚少，本研究以此屬18個品種或栽培品種為親本，進行雜交或自交推估葉斑及花色之遺傳模式；另探討‘Lemon Aide’ (綠葉) 與 ‘Choco Brown Soldier’（棕葉）在不同光積值（daily light integral, DLI）下，生長、葉綠素螢光參數及開花反應。此外，評估 ‘Chocolate Soldier’、 ‘Lemon Aide’ 與 ‘Choco Brown Soldier’在不同日夜溫下的光合作用參數、葉綠素螢光參數、生長與開花表現，並透過葉綠素螢光參數指標篩選具觀賞價值且相對耐低溫之新品系。 遺傳結果顯示葉中肋條帶（M_）與花青素累積（A_）由顯性基因控制，然分別受到不同的顯性抑制基因（S與I）上位抑制。喜蔭花葉斑來自三種機制：氣隙型、氣隙型與色素型結合，或葉綠素缺乏與色素型結合。花色遺傳結果顯示紅花對黃花具顯性，而紅花與紫花或白花雜交產生粉紅色花，推測為不完全顯性遺傳。 優化光照條件對喜蔭花生產至關重要。本研究探討8 小時短日照與 16 小時長日照下與不同光強度所形成的DLI對 ‘Lemon Aide’ 與 ‘Choco Brown Soldier’ 生長、葉綠素螢光參數及開花的影響。隨著 DLI 從1.4增加至11.5 mol·m⁻²·d⁻¹， ‘Lemon Aide’ 的葉片數及走莖數隨之上升，而 ‘Choco Brown Soldier’ 在 5.8 mol·m⁻²·d⁻¹ 後漸趨緩。兩栽培種的總葉面積、平均走莖長、地上部乾重在 5.8 mol·m⁻²·d⁻¹ 時達到峰值，之後漸趨緩或下降。隨著 DLI 增加，平均葉面積及SPAD-502值下降，其中 ‘Lemon Aide’ 在較高 DLI 下黃化更明顯。葉片厚度隨 DLI 增加而增加。葉綠素螢光參數（Fo、Fm、ΦPSII 和 Fv/Fm）隨 DLI 增加而下降，而 ‘Choco Brown Soldier’ 數值較為恆定，推測葉片具花青素光化學效率較穩定。 ‘Choco Brown Soldier’ 在 DLI ≥ 2.9 mol·m⁻²·d⁻¹ 時會開花，在 5.8 mol·m⁻²·d⁻¹ 長日照下開花數增加，並在8.6 mol·m⁻²·d⁻¹ 時趨於平穩。 ‘Lemon Aide’ 在145天處理期間未開花。 溫度試驗結果顯示，‘Chocolate Soldier’ 在 25/20 與 30/25 °C 下生長與開花佳，而 ‘Choco Brown Soldier’ 和 ‘Lemon Aide’ 在 25/20 °C 則在莖徑、走莖數、乾鮮重等各生長指標表現較佳。在15/13 與35/30 °C下， ‘Chocolate Soldier’ 於處理期間Fv/Fm波動，顯著降低開花數、光合作用速率及走莖數等生長指標，顯示逆境；於15/13 與35/30 °C逆境下，葉綠素螢光參數顯示棕葉栽培種‘Choco Brown Soldier’之Fo較低，Fm亦較低且非光化學淬滅（qN）較高，推測葉片花青素累積有助提升抗逆性與環境適應力。 將四支喜蔭花雜交後代品系在30/25 °C（適當）與15/13 °C（低溫逆境）條件下進行28天低溫耐受性評估。在15/13 °C下， ‘Frosted Emerald’ × ‘Bloomlover’s Purple Passion’、‘Bloomlover’s Purple Passion’ × ‘Suomi’、與‘Thad’s Yellow Bird’ × ‘EC’s b-g’之品系，其葉面積顯著降低、葉片ΦPSII、Fv/Fm與SPAD值明顯下降。而 ‘Tiger Stripe’ × ‘Frosted Emerald’之後代品系，葉面積降低最小且具相對穩定的葉綠素螢光參數及最佳觀賞價值，顯示其具良好的低溫耐受性與觀賞潛力。

Episcia exhibits diverse leaf traits, flower colors, and shade tolerance, making it suitable as indoor flowering foliage plants. However, research on their cultivation and genetics remains limited. In this study, 18 species or cultivars of Episcia were used as parental lines for hybridization or selfing to estimate the inheritance patterns of leaf variegation and flower color. Additionally, growth, chlorophyll fluorescence parameters, and flowering responses of ‘Lemon Aide’ (green-leaved) and ‘Choco Brown Soldier’ (brown-leaved) were evaluated under different daily light integrals (DLIs). Furthermore, photosynthetic parameters, chlorophyll fluorescence parameters, growth, and flowering performance of ‘Chocolate Soldier’, ‘Lemon Aide’, and ‘Choco Brown Soldier’ were assessed under varying day/night temperature regimes. Based on chlorophyll fluorescence indicators, a new line with both ornamental value and relatively high low-temperature tolerance was selected. Genetic analysis revealed that midrib striping (M_) and anthocyanin accumulation (A_) are each controlled by a dominant gene, but are epistatically inhibited by different dominant suppressor genes (S and I, respectively). Leaf variegation in Episcia was found to result from three distinct mechanisms: air-space type, a combination of air-space type and pigment type, or a combination of chlorophyll-deficient type and pigment type. Flower color inheritance indicated that red flowers are dominant over yellow, whereas crosses between red and either purple or white flowers produced pink flowers, suggesting incomplete dominance. Optimizing light conditions is essential for Episcia production. This study examined the effects of DLI, derived from varying light intensities under 8-h short-day and 16-h long-day photoperiods. As DLI increased from 1.4 to 11.5 mol·m⁻²·d⁻¹, leaf and stolon numbers of ‘Lemon Aide’ increased steadily, whereas ‘Choco Brown Soldier’ plateaued beyond 5.8 mol·m⁻²·d⁻¹. In both cultivars, total leaf area, average stolon length, and shoot dry weight peaked at 5.8 mol·m⁻²·d⁻¹ and then stabilized or declined. Average leaf area and SPAD-502 values decreased with increasing DLI, with ‘Lemon Aide’ exhibiting more pronounced chlorosis under higher DLI. Leaf thickness increased as DLI increased. Chlorophyll fluorescence parameters (Fo, Fm, ΦPSII, and Fv/Fm) declined with increasing DLI, but remained relatively stable in ‘Choco Brown Soldier’, suggesting that anthocyanins may contribute to greater photochemical stability. ‘Choco Brown Soldier’ began flowering at DLI ≥ 2.9 mol·m⁻²·d⁻¹, with flower number increasing under 5.8 mol·m⁻²·d⁻¹ long-day conditions and leveling off at 8.6 mol·m⁻²·d⁻¹. ‘Lemon Aide’ did not flower during the 145-day treatment period. Temperature treatments showed that ‘Chocolate Soldier’ exhibited optimal growth and flowering at 25/20 °C and 30/25 °C, while ‘Choco Brown Soldier’ and ‘Lemon Aide’ performed best at 25/20 °C in stem diameter, stolon number, biomass, and other growth index. At 15/13 °C and 35/30 °C, ‘Chocolate Soldier’ displayed fluctuating Fv/Fm, reduced flower number, photosynthetic rate, and stolon production, indicating stress. Under these stress conditions, the brown-leaved ‘Choco Brown Soldier’ had lower Fo and Fm but higher qN, suggesting that anthocyanin accumulation in leaves may enhance stress tolerance. Low-temperature tolerance was further assessed in four progeny lines at 30/25 °C (favorable) and 15/13 °C (stress) for 28 days. At 15/13 °C, progeny lines ‘Frosted Emerald’ × ‘Bloomlover’s Purple Passion’, ‘Bloomlover’s Purple Passion’ × ‘Suomi’, and ‘Thad’s Yellow Bird’ × ‘EC’s b-g’ showed marked reductions in leaf area, ΦPSII, Fv/Fm, and SPAD. In contrast, ‘Tiger Stripe’ × ‘Frosted Emerald’ exhibited the smallest decrease in leaf area, stable chlorophyll fluorescence parameters, and high ornamental value, indicating good low-temperature tolerance and potential as a new cultivar.