果實成熟度、種子刻傷處理與培養基組成對流蘇種子整齊萌芽之影響

Effect of Fruit Maturity, Seed Scarification and Medium Composition on Germination Uniformity of Chionanthus retusus Seeds

本研究以含種子長徑大於0.8cm之流蘇（Chionanthus retusus Lindl. &Paxt.）綠色及紫色果實做為參試材料，探討在不完全無菌操作下，不同果實成熟度、種子處理及培養基組成對種子整齊發芽之影響，以及在完全無菌操作下之裸胚培養的最適條件。在不完全無菌操作下，除綠果種子污染率較紫果種子為低外，二者於發根及胚芽發生率（上胚軸生長率）之表現並無差異。去殼（內果皮）後刻傷種子胚乳，並添加4mg.L^(-1)激勃素（gibberellic acid；GA3），可以部分打破休眠限制，在培養後20天時獲得11.7%之發芽率。以裸胚處理並添加2mg.L^(-1)GA3，可以有效突破種子休眠限制，在培養20天時獲得83.3%之發根率及60%的發芽率。在完全無菌的培養條件下，將裸胚培養於含WPM（Woody Plant Medium）為鹽類，添加2mg.L^(-1)GA3的洋菜培養基中，可以完全突破種子休眠限制，在培養7天時胚根可以長至1.5cm，在14天時可獲得平均根長度為4.2cm，芽長度為1.3cm的幼苗，在30天時可以獲得100%的成苗率。 Staggered germination due to epicotyl dormancy in Chionanthus retusus Lindl. & Paxt. is a severe obstacle as the species is mainly propagated by seeds. Seeds from two stages of fruit maturity, green-(110-120 days after blooming) or purple-colored (120-130 days after blooming), with a fruit size of than 0.8 cm in axial length were used. Effects of fruit maturity, different seed treatments, and medium compositions of in vitro embryo culture on germination uniformity were studied. There was no difference in the percentage of radicle protrusion or eipcotly growth between seeds from green and purple fruits. However, a higher ratio of microbial contamination was found in seeds from purple fruits. Endosperm scarification after removal of the shell and treatment with 4 mg.L^(-1) GA3 resulted in 11.7% germination after 20 days of incubation. Naked embryos treated with 2 mg.L^(-1) GA3 increased the percentages of radicle protrusion and epicotyl growth to 83.3% and 60%, respectively. Seed dormancy was completely released when the embryo was cultured in a medium containing Woody Plant Medium salts with 2 mg.L-1 GA3 under aseptic conditions. Such treatment resulted in an average radicle length of 1.5 cm on day 7 and of 4.2 cm on day 14. The length of epicotyl reached 1.3 cm after 14 days inoculation and all embryos developed into seedlings after 30 days of incubation.