夏季遮陰及生長調節劑對仙丹花生長與開花之影響

Effects of Shading in Summer and Growth Regulators on the Growth and Flowering in Ixora Spp.

在夏季以遮陰網行遮陰處理，結果矮仙丹盆栽遮陰30%之植株較遮陰60%及對照組產生較多花芽，且植株外觀較佳。而夏季遮陰的中國仙丹植株較對照組（全日照）高大，但僅遮陰30%的植株有少數花芽形成。以GA3（50, 100, 200ppm）、paclobutrazol （250, 500, 1000, 1500ppm）及ethephon （100, 200, 300ppm）噴施處理矮仙丹及中國仙丹，結果以paclobutrazol促進矮仙丹花芽形成及矮化植株的效果最好，且農度愈高植株愈矮。中國仙丹在第一次處理後，僅paclobutrazol和ethephon處理可矮化植株，但是所有處理之植株都沒有花芽產生。於8個月後再以相同藥劑得理一次（此時枝條已較為成熟），結果以paclobutrazol處理者可產生許多側花芽，且農度愈高，植株愈矮，其中以250ppm處理的植株外觀較佳。GA3處理可使矮仙丹和中國仙丹提早開花，且會使花枝條伸長。ethephon處理對矮仙丹及中國仙丹植株生長和開花並有明顯的效果。

In summer, the plants of Ixora williamsii cv. Sunkist under 60% or 30% shading had more flowers and better performance than those under full sunlight. The Ixora chinensis plants under shading were taller than those under full sunlight, but all the plants had no flowers under either shading or full sunlight.The plants of Ixora williamsiicv. Sunkist were sprayed with GA3 (50, 100, 200ppm) paclobutrazol (250 500 1000 1500ppm) and ethephon (100 200, 300ppm). It resulted that paclobutrazol had the best effect on decreasing plant height and promoting flower formation Ixora chinensis plants were treated with the same chemicals, and only paclobutrazol and ethephon could shorten the shoots, but there was no effect on flower formation in every treatment. The Ixora chinensis Lam, plants were treated with the same chemicals again after 8 months (the shoots were more mature). It resulted that paclobutrazol could promote lateral flower buds formation, and the treated plants were shorter as the concentration was higher. And the plants sprayed with 250ppm paclobutrazol had better quality than other treatments. GA3 promoted flowering in Ixora williamsii cv. Sunkist and Lion chinensis, but elongated the flower shoots, Besides, ethephon had no obviously effect on growth and flowering in those two Ixora plants.