金花石蒜（Lycoris aurea Herb.）預生花芽分化與發育特性及其誘導因素探討

Studies on Induction and Development of Preformed Floral Buds in Lycoris aurea Herb

金花石蒜（Lycoris aurea Herb.）花芽呈預生型，早在二月下旬綠株期初級莖軸之莖頂便開始進行生長相之變換，內外皮細胞旺盛分裂造成莖頂廣平，是為花芽創始。接著次頂分生組織盛行垂軸分裂，提昇莖頂並分化出一對苞片原體。由花芽創始、苞片與小花器官原體分化及配子形成至抽苔開花約需7～8個月，其發育階段在植株間變異甚大。四至五月葉片群老化時，種球花芽發育程度及發生頻率每年不同，於七十九年較為快速，63%集中於四分子期及配子形成，其餘37%為停滯於花芽創始期。八十年甚不一致，有42.3%分別發育為苞片原體、小花始體、花被原體及雄蕊始體等階段，而57.7%為營養芽或創始期。兩年中四〜五月花芽分化至小花始體以上之總頻率，與當年之抽苔開花率相近，故種球花芽檢定可供當年開花潛力之指標。母球栽植在框箱生長於30/25°C、溫室（28±2°C）、25/20°C及20/15°C之條件，其抽苔時間依序而提早，花序品質亦隨低溫而改善，但花梗長度在20/15°C最短，抽苔開花率則無差異。持續高溫條件促進營養生長，延遲葉片老化，或呈常綠型，翌年中皆無花芽分化現象。20/15°C側芽抽葉受限制並不完全老化，雖能夠花芽分化，但頻率低且帶葉開花。高溫生長難休眠之綠株，經20/10°C及光週9小時處理，再移至高溫，可促使葉片老化及抽苔開花，顯示花芽分化需低溫及變溫。但若延至三月後變溫處理，則無誘導花芽分化效果，感應臨界期可能為一重要因素。

The initiation of reproductive growth of Lycoris aurea Herb. occurred at greening leaf stage in the late February. The shoot apex of primary axis was characterized by active division in the tunica and subtunica layers conducted to flat and broad apical meristem. Actively transverse division and cell enlargement of subapical meristem raised the shoot apex and initiated spathe primordia which was assigned as stage Ⅱ. The timetable in subsequent development of floret and gametogenesis varied with plants and years. During April to May, the scale leaves were senescent, the frequency of over stage Ⅱ bulbs of 1990 and 1991 was respectively examined to be 63% and 46% coincident with flowering percentage in September to October, evided that the stage Ⅱ floral bulbs could be served as index of flowering potential. High temperature regimes of 25/20°C、30/25°C and greenhouse (28 ± 2%) stimulated vegetative growth of daughter bulb, that displayed evergreening and failed to enter reproductive phase in three successive years. The temperature at 20/15°C condition restricted leaf emergence, and only 10% daughter sproduced flower accompanying a few green leaves, elucidated that the destination to reproductive growth might not just require low temperature. The greening plants were transferred to 20/10°C -9 hrs photoperiod then returned to high temperature condition, which were inducible to bloom, reflected that the floral initiation required low temperature and changing codition, and also exhibited a critical period before March in response to induction condition.