溫度對非洲鳳仙花生育及光合作用的影響

Effects of Temperature on Growth and Photosynthesis in Four Cultivars of Impatiens (Impatiens walleriana Hook. f.)

本研究以非洲鳳仙花（Impatiens walleriana Hook.f.）的Accent Cranberry、Accent Scarlet、Accent Salmon及Accent White品種為材料，試驗不同日／夜溫度15／13、20／15、25／20、30／25及35／30℃對其生育及光合作用的影響。五種不同日夜溫度設定，經實際測量之日夜均溫分別為16.1、17.1、22.4、27.0、31.5℃。四個參試品種於日／夜均溫16.1℃時生育之株高最矮，隨著溫度上升至27.0℃時最高。於31.5℃環境生長的植株株高、葉片數及分枝數均明顯下降。植株於27.0℃以下溫度處理30天寬幅均可達到15 cm以上，覆蓋性良好。在16.1-27.0℃之間，植株地上部乾重隨溫度升高而呈現緩慢增加的趨勢，而根部則隨溫度升高而有下降的趨勢。在31.5℃高溫環境下則幾乎停止生長。根系受高溫抑制生長更甚於地上部。開花天數隨著溫度升高而減少。升至31.5℃時花朵縮小，甚至部分花苞不綻放。四個參試品種對高溫之反應有明顯差異。以光合作用測定儀測定植株葉片淨光合作用，於17.1℃至22.4℃時有最高淨光合作用值，CO2吸收速率平均可高達14µmol•m^(-2)•s^(-1)以上。當均溫高於27.0℃時則快速下降。本試驗結果，當均溫高達31.5℃時，非洲鳳仙花的生育及光合作用受到抑制，且根部受到影響的程度大於地上部。因此，臺灣夏天之高溫不利非洲鳳仙花的生長。 The effects of different day/night temperatures on growth and photosynthesis of four cultivars of impatiens (Impatiens walleriana Hook. f.) were studied. Cultivars included were 'Accent Cranberry', 'Accent Scarlet', 'Accent Salmon' and 'Accent White'. Potted plants placed in a phytotron at different day/nighttemperatures of 15/13, 20/15, 25/20, 30/25 and 35/30℃. The mean temperatures measured were 16.1, 17.1, 22.4, 27.0, and 31.5℃, respectively. The mean plant height was shortest at 16.1℃ and tallest at 27.0℃. Theheight, number of leaves and number of branches all declined at 31.5℃. Plant width reached 15 cm or aboveat 27.0℃, providing a good ground cover. As temperature increased from 16.1 to 27.0℃, the dry weight ofshoots increased but that of roots decreased. Shoot and root growth almost stopped at 31.5℃. High temperature affected the root growth more than shoot growth. The flower diameter and days from sowing to flowering decreased in all cultivars as temperature increased from 16.1 to 27.0℃; and the plants did not flower normally at 31.5℃. The highest rate of net photosynthesis in four cultivars was observed at 17.1℃ to 22.4℃ when their CO2 uptake rate reached≧14μmol•m^(-2)•s^(-1). The net photosynthesis decreased sharply at 31.5℃. A high daily mean temperature of 31.5℃ or above, not uncommon in the summer of Taiwan, would impair the root growth more seriously than shoot growth, and sharply decrease CO2 uptake in impatiens.