臺灣地區平戶杜鵑之開花習性

The Flowering Habits of Hirado Azalea in Taiwan

針對台大校園數十年生的四個平戶杜鵑品種．白琉球（Rhododendron mucronatum）、豔紫杜鵑（R. pulchrum）、粉白杜鵑（R. mucronatum cv. Akemono）及大紅杜鵑（R. scabrum）定期記錄觀察其開花習性。結果顯示此四種平戶杜鵑品種營養芽萌發後約需二至三個月始具有形成花芽的能力。各品種除大紅杜鵑外於五月間有少量花芽於一次枝上形成，花季盛開之花芽多為七月底至八月中旬於二次枝上形成。大紅杜鵑之花芽約在八月中至九月形成。各品種花芽大都在十月中旬至下旬各花器外觀已分化完成。調查顯示杜鵑花芽及各花器在冬季持續生長，並未因台灣冬季的低溫而停止，因此平戶杜鵑在北台灣平地冬季似乎並未進入休眠。調查粉白杜鵑盆栽顯示，自萌芽至花芽形成與自花芽形成至花苞顯色或開花，五月形成的花芽均較七月形成的花芽需較長的時間，然因前者花芽較早形成，故大致仍較後者之花芽提早開放。

The flowering habits of four species ofHirado azalea that grown on campus of National Taiwan University for over forty years were investigated at a two-week intervals. The results showed that the shoots needed two or three months after sprouting to aquire the ab山ty of floral initiation. All tested species expect R. scabrum could form flower buds in May. But the major periods of floral bud formation derived from the second twigs were from late July to mid-August in R. pulchrum, R. mucronatum, and R. mucronatum cv. Akemono, and mid-August to September in R. scabrum. All the floral structures had already differentiated in middle or late October. As flower buds still enlarged in the winter, it appeared that there may be no endodormancy occurrence in these buds. The flower buds of R. mucronatum cv. Akemono, those formed in May, required more days to form flower buds and to develop flower structures than those formed in July. But because the former flower buds formed earlier, they still bloomed before the latter buds.