水楊酸複合藥劑促進非洲鳳仙與四季秋海棠耐熱性之研究

Abstract

非洲鳳仙(Impatiens walleriana Hook. f.)與四季海棠(Begonia × semperflorens-cultorum Hort.)是臺灣重要的冷季花壇植物，佔全臺冷季草花總產量前二名。由於全球氣候不斷暖化，促使冷季草花因高溫影響，生長與品質表現不佳。本研究先探討葉綠素螢光作為冷季作物耐熱性指標之可行性，其次探討單一化學藥劑與複合藥劑對提高非洲鳳仙與四季海棠高溫耐受性之影響。 在以葉綠素螢光作為耐熱生理指標方面，葉綠素螢光偵測可快速、有效且精確分析植物之耐熱性(heat tolerance)，故本研究以此作為高溫逆境(heat stress)之生理評估依據，探討植物於特定時間下之關鍵溫度，作為評斷植物對高溫之耐受程度。結果顯示，冷季蔬菜利用40oC處理30分鐘之相對葉綠素螢光值，作為判斷冷季蔬菜耐熱程度之依據；冷季草花則以45oC處理30分鐘之相對葉綠素螢光值，作為判斷耐熱程度之技術。 以單一藥劑提高非洲鳳仙高溫耐受性方面，本研究將非洲鳳仙‘小精靈’(I.‘Super Elfin’)幼苗於高溫前2小時，預先進行葉片噴施單一藥劑水楊酸(salicylic acid，SA) (50、100、150 μM)、氯化鈣(calcium chloride，Ca) (5、10、15 mM)、甜菜鹼(glycine betaine，GB) (5、10、15 mM)及海藻糖(trehalose，Tre) (0.5、1.5、2.5 mM)，隨後予以短暫高溫(45oC, 30分鐘)處理，高溫後立即測量葉綠素螢光值。結果顯示，100 μM SA、10 mM Ca、10 mM GB與1.5 mM Tre四種藥劑均能有提高非洲鳳仙幼苗於高溫下之耐熱性，對提高之相對葉綠素螢光值、維持正常之光合作用速率、維持較高之葉片品質與完整性、減少因高溫失水導致葉片溫度降低及提高幼苗存活率有助益。 單一藥劑與複合藥劑提高非洲鳳仙高溫耐受性之研究方面，高溫逆境前2小時葉片噴施有效單一藥劑(100 μM SA、10 mM Ca、10 mM GB、1.5 mM Tre)，及複合藥劑(50 μM SA+ 5 mM Ca、50 μM SA+ 5 mM GB及50 μM SA+ 0.75 mM Tre)，並以短暫高溫(45oC, 30分鐘)評估藥劑促進非洲鳳仙耐熱之有效性。結果顯示，50 μM SA + 5 mM Ca藥劑有效提高相對葉綠素螢光值、淨光合作用能力及Rubsico利用效率，有效提高非洲鳳仙對高溫之耐受能力，進一步探討不同SA與Ca濃度比例(25 μM SA + 7.5 mM Ca、50 μM SA + 5 mM Ca、75 μM SA + 2.5 mM Ca)之複合藥劑，結果顯示，75 μM SA + 2.5 mM Ca組合最能提高非洲鳳仙對高溫之耐受性。 以單一藥劑與複合藥劑提高四季海棠於高溫栽培之研究方面，四季海棠‘超級奧運’ (B.‘Super Olympia red’)於高溫逆境前2小時預葉片噴施100 μM SA、10 mM Ca、10 mM GB、1.5 mM Tre、50 μM SA+ 5 mM Ca、50 μM SA+ 5 mM GB及50 μM SA+ 0.75 mM Tre化學藥劑，於臺大人工氣候室35/30oC下栽培14天。結果顯示，外施 SA、 Ca、 GB、 Tre及其複合配方之化學藥劑均能有效提高四季海棠對高溫之耐受性，使植株較緊密，維持外觀品質及光合作用能力，亦保護葉綠素不受高溫降解。綜合藥劑效果與藥劑成本，以藥劑50 μM SA+ 5 mM Ca兼具成本低廉與耐熱潛力之優勢。 葉片噴施化學藥劑為一種簡單、有效率的方法，葉施SA與Ca之複合藥劑有效提高冷季草花之高溫耐受性。葉片噴施50 μM SA+ 5 mM Ca複合藥劑證實可提高非洲鳳仙與四季海棠於短暫高溫或高溫栽培環境之耐受性，耐熱效果更優於單一施用SA或Ca，顯示複合藥劑具有加乘性。以經濟栽培而言，75 μM SA + 2.5 mM Ca複合藥劑兼具耐熱效果與低成本，具備開發耐熱性藥劑之潛力。若考量夏季高溫以外之環境逆境因子如高光度，加入其他藥劑供試，研發耐多重逆境之藥劑，並將冷季草花於夏季實際栽培進行試驗，是未來進一步可研究之方向。

Impatiens (Impatiens walleriana Hook. f.) and wax begonia (Begonia × semperflorens-cultorum Hort.) are the most important bedding plants in cool-season. Their year-production amounts are the top two among all cool-season bedding plants in Taiwan. However, the continuous global warming effect has brought negative impacts to the growth and quality of cool-season bedding plants. Therefore, the aim of this research is to select proper types of both single and combined-chemicals that may improve the heat tolerance of impatiens and wax begonias, and to optimize the concentrations of these chemical treatments. Chlorophyll fluorescence determination method is a fast, efficient and accurate indicator of heat tolerance. Under specific time, the key temperature can be used as an indicator of heat tolerance of plants. The results indicated that the relative chlorophyll fluorescence under 40oC in 30 min treatment and 45oC in 30 min treatment are good indicators for the evaluation of the heat tolerance of cool-season vegetables and cool-season bedding plants, respectively. In the first part of this research, the impatiens were treated by foliar sprays of salicylic acid (SA) (50, 100, 150 μM), calcium chloride (Ca) (5, 10, 15 mM), glycine betaine (GB) (5, 10, 15 mM) and trehalose (Tre) (0.5, 1.5, 2.5 mM) individually in 2 h and followed by 45oC heating. The result showed that 100 μM SA, 10 mM Ca, 10 mM GB and 1.5 mM increased the relative Fv/Fm value and net photosynthetic rate, survival rate of impatiens, as well as maintain the quality of leaf, lower the loss of leaf water potential under heat stress. After selecting the appropriate concentrations of the single chemicals (100 μM SA, 10 mM Ca, 10 mM GB、1.5 mM Tre), the detailed studies of the combined-chemicals are approached. The results indicated that 50 μM SA + 5 mM Ca improved the relative Fv/Fm value, net photosynthetic rate and Pn/Ci of impatiens under heat stress. Next, the experiment of the concentration ratio between SA and Ca are performed. The results showed that 75 μM SA + 2.5 mM Ca is the best composition for impatiens to tolerate heat. Furthermore, the wax begonias are treated with the sprays of 100 μM SA、10 mM Ca、10 mM GB、1.5 mM Tre、50 μM SA+ 5 mM Ca、50 μM SA+ 5 mM GB and 50 μM SA+ 0.75 mM Tre, followed by cultivation under 35/30oC phytotron for 14 days. The results showed that all single- and combined-chemicals are efficient for wax begonia to tolerate high temperature, and they also are able to maintain compact shape, good quality and net photosynthetic rate. Moreover, the chemicals could protect chlorophyll from degradation due to high temperature. Both single- and combined-chemicals improved heat tolerance for wax begonia. Overall, 50 μM SA+ 5 mM Ca is most cost-effective for growers. In conclusion, according to the result, the spray with 50 μM SA+ 5 mM Ca combined-treatment has been proven to have premium effect for enhancing heat tolerance of impatiens and wax begonias, which is better than applying SA or CA individually. Nevertheless, 75 μM SA + 2.5 mM Ca is considered to be the most cost-effective combined treatment, which can be further applied to commercial grower. For future development of new combined-chemical treatments, considering other stress factors, such as high light intensity, will be necessary.