仙丹花之間花習性與修剪時期對矮仙丹生長及開花之影響

The Flowering Habits of lxora spp. and Effects of Pruning Time on the Growth and Flowering in lxora williamsii cv. Sunkist

本研究探討仙丹花在台灣北部地區之開花習性和矮仙丹綠籬之適合修剪時期。由實際觀察得知，矮仙丹在台灣北部地區從5月至11月皆可開花，7月為盛花期，花序由肉眼可見至開花約需1個月，而由開花至凋謝亦需1個月。一年中以5月形成的花芽之開花期最長，之後開花期隨著花芽形成的延後而漸短。中國仙丹的花序發育過程和矮仙丹類似，惟植株比矮仙丹耐寒，因此在台灣地區可終年開花。在不同月份修剪矮仙丹綠籬後，新生枝條大多在7至9月有較大的生長量，其中以3月及5月修剪的枝條生長速率最快，且當年即能形成新的花芽，7月及以後修剪的枝條在當年無法形成新的花芽。3月至11月修剪的植株，新萌發的枝條到了冬季易受寒害，尤以9至11月修剪後萌發的新梢較為嚴重；而1月修剪者則因新梢萌發延遲，故冬季寒害輕微，且春天時可萌發較多的新芽。此外，7到11月的修剪對於當年的開花沒有明顯的促進作用，而3至5月修剪則會減少當年盛花期的開花量。由此推論，矮仙丹最適合修剪的時期應該在冬末春初的1至2月間。

The flowering behavior and optimum pruning time of ixoras (lxora spp.)were investigated. In north Taiwan, lxora williamsii cv. Sunkist is flowering from May to November, and full boom in July. The duration from inflorescence visible to anthesis takes about one month, and from anthesis to all flowers abscission is also about one month. The flower buds which formed in May and flowering in July have the longest flowering duration in the year, the following formed flower buds in the year had shorter flowering duration. The developmental processes of inflorescence of lxora chinensis is similar to lxora williamsii cv. Sunkist. lxora chinensis has more hardness than lxora williamsii cv. Sunkist, so it can flower all of the year in Taiwan. Not concerning in pruning date of lxora williamsii cv, Sunkist., the optimum growing period of new shoots emerged after pruning are during July to September. The growth rate of new shoots emerged from the shoots pruned in March and May have faster than these pruned in July to November, and could form flower bud in the current year. The new shoots emerged from March to November pruned plants will get chilling injury in winter, but none for • those from January pruning. Besides, pruning from July to November do not improve the flower formation, and pruning from March to May decrease the flowering covering rate in full bloom period. So, from January to February will be the favorite time for pruning in hedges of lxora williamsii cv. Sunkist.