日／夜溫與處理時期對黃金石斛蘭開花之影響

Effect of Day/Night Temperature and Duration on Flowering of Dendrobium aggregatum Roxb

本研究旨在探討黃金石斛蘭（Dendrobium aggregatum Roxb.）經不同日／夜溫度與處理時期之長短對開花之影響。日／夜溫20／15℃處理可促進花序形成及花序發育；經處理45天之植株花序形成率高達83%-100%，且其花序數較其他處理多。日／夜溫30／25℃處理組之花序形成率甚低。涼溫處理天數愈長，處理後到可見花芽所需天數愈短。大苗以20／15及25／20℃處理90天，其花序形成所需天數僅9.3-10.0天，中苗則須11.3-11.8天。以20／15℃處理組單朵花開花壽命22.0天，比30／25℃處理組的13.9天長很多。又大苗的開花表現優於中苗。一部分30／25℃處理的植株上，有高芽發生，顯示環境條件不適合開花，潛伏芽持續進行營養生長形成高芽。另外25／20或20／15℃的涼溫比30／25℃高溫較有利於花朵整體明度和彩度表現。日／夜溫20／15℃處理可獲得較高品質之開花表現；而25／20℃處理則品質略次，但仍達可販售之優良品質範圍。 This study evaluated the effect of various day/night temperatures and durations on the flowering of Dendrobium aggregatum Roxb. Plants received ≧45 days of 20/15℃ treatment had the highest percentage of inflorescence formation as well as the highest number of inflorescences per plant. Those received 30/25℃ treatment had the lowest while those received 25/20℃ treatment fell in between. The longer duration of cooling treatment, had the faster floral bud formation after the treatment. Visible flower buds formed in 9.3-10.0 days for larger plants (in 10.5-cm diameter pots) and in 11.3-11.8 days for medium plants (in 7.5-cm diameter pots) after 90 days of either 20/15℃ or 25/20℃ treatment. Plants received 20/15℃ treatment had a longer floral longevity than those received 30/25℃ treatment. Larger plants also had a better flowering performance than medium plants. Some plants after 30/25℃ treatment had keikis formation on the pseudobulbs, probably because high temperatures promoted vegetative growth and induced the latent buds to become keikis. Cool temperature (25/20 or 20/15℃) treatments also resulted in brighter and higher chroma flowers. The 20/15℃ treatment generated the highest quality flowers while 25/20℃ generated somewhat poorer but still commercially acceptable quality flowers.