大野牡丹繁殖及利用性評估

大野牡丹 (Astronia formosana) 屬於野牡丹科 (Melastomataceae)，在台灣為單屬(野牡丹屬，Astronia genus)單種，為原住民的傳統民族植物，且因其葉背呈鏽色，光照下呈現金光閃閃的樣貌，適合開發作為觀賞植物，但此物種的繁殖生物學尚未明確，故本研究期能針對大野牡丹有性及無性繁殖進行試驗，包括：種子繁殖、高壓繁殖及扦插繁殖，並評估其利用性，建立合適之繁殖模式。試驗結果顯示：大野牡丹種子不論是否經過層積處理，種子皆能在15°C/20°C、20°C/25°C的變溫環境下發芽，但未經層積處理 (即採即播) 的種子在25°C/30°C的環境下無法發芽。在高壓繁殖試驗下，研究發現大野牡丹的枝條發根力不弱，縱未施用任何生長調節劑，大野牡丹的枝條透過環剝處理，仍可仰賴母株的養分及水分產生不定根，但需注意減少人為操作造成的不可逆傷害或動物破壞，維持水分，以利發根。而扦插繁殖試驗結果顯示，不論成年性和幼年性枝條皆能誘導發根，但以幼年性枝條發根效果較佳，成年性枝條普遍發根率低。扦插繁殖在不施用生長調節劑或施用低濃度生長調節劑 (IBA 100 ppm)，配合珍珠石作為介質的條件下，有較佳的發根效果。此外，添加外源碳水化合物可提高幼年性的枝條的發根率，但對成年性枝條無明顯助益。以利用性的角度評估，大野牡丹的種子未經層積處理能順利發芽，推測其種子不具休眠性。雖能以有性生殖順利繁殖，但小苗生長緩慢，需耗費較多的人力時間成本；而無性生殖法中的高壓繁殖法雖有不錯的效果，卻較費工，不易大量繁殖，因此本研究認為大野牡丹最適繁殖方法為幼年性枝條之扦插繁殖法，為解決不易於野外取得大量幼年性枝條材料的困境，建議建立採穗母樹，透過重採剪方式於低位處誘導較幼年性的新枝條，再剪除頂芽，誘導大量枝條作為扦插繁殖材料。

關鍵字

大野牡丹；種子繁殖；扦插繁殖；高壓繁殖

並列摘要

Belonging to family Melastomataceae and genus Astronia, the Astronia formosana is a monotypic species in Taiwan. It has been used as ethical plants by the indegenous people. Due to the golden looking of the rusted-color-leaves on the rear side under the light, it has the potential to become an ornamental plant in the markets. However, reproduction of this plant has been unclear that requires future investigation. Therefore, this research aims to find appropriate reproduction conditions and evaluate the potential utilization through a series of experiments by either the sexual or the asexual reproduction methods, including seed propagation, air-layering, and cutting. Research results found that whether applying stratification process on seeds, they expressed successful germination under temperature variations among 15/ 20°C, 20/ 25°C. In contrast, seeds without stratification did not show successful germination under temperature variations of 25°C/ 30°C. Based on the air-layering experimental results, Astronia formosana demonstrated good root developments by girdling treatment. Without growth regulator the branch can still develop adventitious roots by obtaining nutrients and moisture from the mother plants. But attention should be paid to reducing irreversible damages during operations or from animal damages to limit the situation of dehydration for survival. Moreover, the cutting experimental results showed that both juvenile shoots and adult stems were able to generate adventitious roots, but juvenile shoots had better rooting rates than adult ones. In terms of cutting propagation, using the pearlite as the medium under no growth regulator or lower concentration growth regulator (IBA 100 ppm) appeared better rooting rates. Furthermore, adding exogenous carbohydrates showed higher rooting rates for juvenile shoots, but no obvious effects were found on adult stems. In terms of utilization, the research results found that Astronia formosana’s seeds can germinate without stratification, which implied that the seeds did not process dormancy. Although sexual reproduction can be successfully applied and utilized, but the slow growth of seedlings may resuilt in greater costs for labor and time. On the other hand, the air-layering in the asexual reproduction method showed good outcomes, but it required more labor that can be difficult for commercialized reproduction. As a result, I suggest using the juvenile-stem-cutting method as the optimal propagation method for Astronia formosana, and establish mother trees to solve the problem of limited available materials in the field. Through removing the top buds by reharvesting and pruning, one can use the juvenile stems to apply the cutting propagation method for reproduction and utilization.