臺灣原生秋海棠屬植物之生長習性

Abstract

原生秋海棠屬植物中不乏具觀賞價值或具育種潛力者。本研究調查數種臺灣原生秋海棠適宜之繁殖溫度及光度，並探討溫度、光度、光週期及養液濃度對生長之影響。 溪頭秋海棠、巒大秋海棠、蘭嶼秋海棠及白斑水鴨腳葉片扦插之存活率均以25/20 ℃處理者較高。於25/20 ℃及30/25 ℃下不定芽數、芽長及新葉數較多。參試秋海棠葉片扦插於53及107 µmol∙m-2∙s-1光度下存活率較高，而不定根數會隨光度由53 µmol∙m-2∙s-1上升 至198 µmol∙m-2∙s-1而減少。 觀察秋海棠於20/15、25/20及30/25 ℃栽培溫度之生長量，評估秋海棠種間對熱適應性之差異，植株株高、葉數、總葉面積、莖及根乾重隨溫度由25/20℃上升至30/25 ℃而減少。高溫30/25 ℃栽培之蘭嶼秋海棠乾物重及淨光合作用速率下降較少。巒大秋海棠於30/25 ℃下無法存活，且對熱較敏感。 蘭嶼秋海棠、白斑水鴨腳、溪頭秋海棠及巒大秋海棠於30.6 ℃高溫栽培2個月後，取剛成熟展開葉，利用24、30、36、42、48、54、60或66 ℃水浴加熱葉圓片20分鐘。相對熱傷害值與水浴溫度呈S形曲線關係，可利用48 ℃水浴溫度鑑別種間細胞膜熱穩定性之差異。將蘭嶼秋海棠、溪頭秋海棠及巒大秋海棠分別置於20/15、25/20及30/25 ℃栽培75天後，栽培於30/25 ℃之蘭嶼秋海棠及溪頭秋海棠之相對熱傷害值較低，且S形曲線顯著較20/15 ℃處理者右移。巒大秋海棠於25/20 ℃下相對熱傷害值較其餘參試之秋海棠高。 為評估秋海棠種間對光度適應性之差異，調查栽培於97、211及315 µmol∙m-2∙s-1光度栽培植株之生長量及光合作用之影響，結果蘭嶼秋海棠之總葉面積、葉數、地上部、地下部乾重、光飽和點及最大光合作用值均於栽培光度由97上升至315 µmol∙m-2∙s-1而增加，顯示蘭嶼秋海棠需光性較高，對光度適應範圍較廣。溪頭秋海棠之光飽和點及最大光合作用值隨栽培光度上升而增加。白斑水鴨腳及巒大秋海棠之光飽和點於三種栽培光度間差異不大且光飽和點低，提高栽培光度無法顯著增加其光合作用效率。四參試種之光補償點均未隨栽培光度上升而增加。 於自然日長(10.3-12.3 小時)、延長日照(17:00-21:00 點燈，日照時間為14.7-15.3 小時)及暗期中斷(接受自然日照，但於22:00 - 02:00 進行暗期中斷)下栽培蘭嶼秋海棠、白斑水鴨腳、溪頭秋海棠、巒大秋海棠及圓果秋海棠142天後，白斑水鴨腳於延長日照及暗期中斷下較早進入花芽分化。蘭嶼秋海棠於自然日長及暗期中斷下花苞可見天數及到花較早，而延長日照處理者無可見花苞。溪頭秋海棠、巒大秋海棠及圓果秋海棠於三種光週處理142天後尚未有可見花苞。 以0%、25%、50%及100%強生氏營養液栽培蘭嶼秋海棠、白斑水鴨腳、鹿谷秋海棠、岩生秋海棠及溪頭秋海棠四個月後調查其生長情形，結果顯示五種原生秋海棠均以處理25%及50%強生氏營養液栽培者之株高較高、葉數較多及總葉面積較佳且地上部及地下部乾重較重。

Some native Begonia species may have potential for the breeding of heat-tolerance or ornamental purposes. This thesis aimed to determine the effects of temperature and irradiance of propergation of leaf cuttings, and to study the the effects of temperature, irradiance, photoperiod and nutrient solution concentration on growth of several Begonia species native to Taiwan. For leaf cutting propagation, highest survival rate of B. chitoensis, B. palmate, B. fenicis and B. formosana occurred at 25/20 ℃. The highest adventitious shoot number, length and new leaf number were measured in cuttings at 25/20 ℃ and 30/25 ℃. Survival rate was higher at 53 and 107 µmol∙m-2∙s-1, while the adventitious root number decreased with increasing photosynthetic photon flux. To evaluate heat tolerence among species, plants of three Begonia species were grown at 20/15℃, 25/20℃, and 30/25 ℃. Plant height, leaf number, leaf area, shoot and root dry weight decreased with increasing temperature. Reduced dry weight and net photosynthetic rate were not so apparent in B. fenicis at 30/25 ℃, as compared with other species. B. palmate was heat sensitive and could not survive at 30/25 ℃. Plant of B. fenicis, B. formosana, B. chitoensis and B. palmate were grown at 30.6 ℃ for two months, and their recently development leaves species were evaluated for cell membrane thermostability measured at water bath temperatures of 24, 30, 36, 42, 48, 54, 60 or 66 ℃ for 20 minutes. The relationship between the relative injury value occurring in leaf tissue discs and treatment temperature was sigmoidal. Reduce relative injury value at 48 ℃ was more apparent in B. fenicis and B. chitoensis than the heat-intolerance B. palmate after 30/25 ℃ treatment for 75 days. Effects of irradiance on growth and net photosynthesis were studied in four Begonia species grown in controlled environments at 97, 211, and 315 µmol∙m-2∙s-1. Leaf area, leaf nimber, shoot and root dry weight, light saturation point and maximum values of net photosynthetic of B. fenicis increased as light intensity increased from 97 µmol∙m-2∙s-1 to 315µmol∙m-2∙s-1. Light saturation point and maximum values of net photosynthetic of B. chitoensis also increased as light intensity increased, while light saturation point and of B. formosana and B. palmata was not affected with increasing light intensity. Light compensation point of four begonia species was affected little with increased light intensity. For photoperiod treatments, plants of B. fenicis, B. formosana, B. chitoensis, B. palmate and B. aptera were grown under natural daylength (10.3-12.3 h), day length extension (14.7-15.3 h) or night interruption (natural daylength with night interruption at 22:00 - 02:00) treatments for 142 days. Flowers initiated earlier under daylength extension and night interruption in B. formosana. Flower initiation occurred earlier under natural day length and night interruption in B. fenicis, but no visible bud formation was observed under day length extension. B. chitoensis, B. palmate and B. aptera did no show visible bud formation at the termination of the experiment. B. fenicis, B. formosana, B. lukuana, B. ravenii and B. chitoensis were fertigated with 0%, 25%, 50% and 100% Johnson’s solution for four months. Plant height, leaf number, leaf area, shoot and root dry weight of five begonia species were higher at 25% and 50% Johnson’ solution than 0% or 100% Johnson’s solution.