溫度對非洲鳳仙花生育及光合作用之影響

Abstract

非洲鳳仙花是台灣秋冬春季節中種植最多的花壇植物種類之一，而夏季高溫度是限制非洲鳳仙花應用最重要的環境因子。非洲鳳仙花的種子均由國外進口，包含5個品種系列共45個商業品種於市區及郊區海拔400 m較冷涼處等不同地點及不同定植季節(12月及3月)以評估其景觀上的整體表現，結果顯示非洲鳳仙花整體表現受到種植地點及種植時期所而影響，而溫度為主要影響非洲鳳仙花的環境因子之一。在合宜的生長溫度下，各品種系列間的表現無顯著地差異且觀賞時期可長達5個月。而在溫度較高或有短暫高溫的情況下，而觀賞期約只可維持3個月左右。 在人工氣候室內設定不同的日/夜溫度從15/13、20/15、25/20、30/25至35/30℃的環境下測試其對4個非洲鳳仙花品種之生育及光合作用的影響。在高溫35/30℃的環境下，非洲鳳仙花地上部的生育包植株高度、葉片數、分枝數、花朶大小、地上部乾鮮重等受到限制。地上部光合作用則於30/25℃時快速下降。根部生長隨溫度升高而下降，在35/30°C之高溫環境下幾乎停止生長。高溫對根部生長大於對地上部生長的影響。 為測試高根溫對非洲鳳仙花生育及光合作用的影響，於生長箱內設定日/夜溫25/20℃環境下，將二品種非洲鳳仙花使用可加溫的水耕箱予以25、27.5、30、32.5及35℃等不同根溫處理6天。結果顯示根溫32.5℃以上會抑制非洲鳳仙花的生長及光合作用的進行；而根溫大於30℃則抑制根部生長。因此，根部生長對高根溫是非常敏感的。於高溫的環境下，降低根部生長溫度，可延長非洲鳳仙花整體景觀表現。

Impatiens are one of the most popular bedding plants used for landscaping during autumn, winter and spring season in northern part of Taiwan. High temperature during summer season impairs the growth of impatiens. The five series of impatiens（Impatiens walleriana Hook.f） including 45 commercial cultivars were planted at the urban and suburban areas in the northern part of Taiwan and planted at different growing seasons of Dec, 2001 and Mar, 2002 to evaluate landscaping performance among cultivars. The results showed that the factors of planting areas and planting seasons affected the growth and performance of impatiens that showed temperature was the major factor. Under optimum temperature circumstance, most impatiens cultivars grew well and performed well until 150 DAT. But heat stress occurred, the results showed difference of performance among 45 impatiens cultivars and plant quality only maintained to 90 DAT. Four cultivars of impatiens (Impatiens walleriana Hook.f.) were studied in a phytotron at different day/night temperature of 15/13, 20/15, 25/20, 30/25 and 35/30°C to investigate the effects of different day/night temperatures on growth and photosynthesis. High temperature 35/30°C impaired the growth and decreased the height, number of leaves, branches, shoot dry/fresh weight and flower size. The net photosynthesis decreased sharply at 35/30°C. As temperature increased from 15/13 to 35/30°C, the dry weight of roots decreased and almost stopped at 35/30°C. High temperature affected the root growth more than shoot growth. The effects of high root temperatures on growth and photosynthesis in two cultivars of impatiens were studied in a growth chamber that the day/night temperature was set at 25/20℃. Five root temperatures were set at 25, 27.5, 30, 32.5 and 35℃ using hydroponic unit equitted with heating system. Results showed that high root temperature would ≧32.5℃ impair plants growth and photosynthesis and root temperature ≧30℃ would inhibit root growth. In conclusion, the root growth of impatiens was sensitive to high root temperature that any way to reduce root temperature would increase landscaping performance.