溫度與GA₃對菊花開花之影響

Effect of Temperature and GA₃ on Flowering of Chrysanthemum morifolium Ramat

菊花「冬王」品種於不同季節及人工氣候室13～30°C生長，在臺灣自然日長於13～20°C週年均能開花，日／夜溫20/15°C花朵分化發育最快品質最好，低溫（l5／13°C）延遲花芽分化與發育。夏秋之自然日長，生長於日／夜溫25/20°C及30／25°C者均不會發生花芽。秋冬春之日長，生長於25／20°C者花芽分化快，但花蕾發育延遲品質不佳； 日／夜溫30／25°C生長者，均不會開花祇少數植株形成柳芽。在13～25°C生長之「冬王」於花蕾可見噴施20ppm GA₃能促進莖之伸長，增加花朵鮮重，提早開花及增進品質。高溫（30／25°C）施GA₃無效。對「新種黃」品種，施GA₃ 10或20 ppm，不但促進莖之伸長，並提高開花率及提早開花。以長日至盛花每週噴施GA₃一次放果最好。

The experiment was undertaken to investigate the effect of various season, day/night temperature, and GA₃ application on the flowering time and quality of chrysanthemums. The winter flowering cv. Tung-Wang, which belongs to the thermonegative group, initiated and developed flower buds to anthesis at day/night temperature of 15/13°C and 20/15°C under year-round. natural daylength in Taiwan. Visible buds formed at temperature from 13 to 30℃ under natural daylength during autumn, winter and spring seasons. However, its growth and flowering were inhibited by high temperature (30/25°C). The flower buds initiation and development were delayed by low temperature (15/13°C). Visible buds appeared rapidly at temperature of 20/15°C and 25/20°C, but development delayed at 25/20°C. The minimum flowering time and best quality was produced by the temperature of 20/15°C. GA₃ applied to chrysanthemum cv. Hsin-Chung-Huang once per week from planting to full bloom increased stem elongation and induced flowering. GA₃ applied to cv. Tang-Wong after bud visible increased stem elongation and fresh weight and hastened flowering time in the temperature range from 13 to 25°C. However, there was no response to GA₃ at temperature of 30/25°C.