耐高溫淹水甘藍苗期生理指標研究

Abstract

甘藍(Brassica oleracea L. var. capitata)是臺灣產量最高之葉菜類作物，但夏季高溫多雨使甘藍生產困難，選拔耐高溫淹水品種為當前甘藍產業所需。本研究以甘藍 ‘228’ 、 ‘臺南2號’ 、 ‘青翠’ 、 ‘初秋’ 、 ‘高峰’ 、 ‘夏秋’ 、 ‘大芯’ 與 ‘臺中2號’ 為試驗材料，探討葉綠素螢光、光合色素、過氧化氫(hydrogen peroxide, H2O2)、抗氧化酵素包括過氧化氫酶(catalase, CAT)、抗壞血酸過氧化酶(ascorbate acid peroxidase, APX) 和穀胱甘肽還原酶(glutathione reductase, GR)、以及丙二醛(malondialdehyde, MDA)和細胞膜熱穩定性(cell membrane thermostability, CMT)，應用於苗期選拔耐高溫淹水甘藍之可行性。2015年臺南田間夏作不淹水之對照組，結球率與葉球重以 ‘228’ 、 ‘高峰’ 、 ‘青翠’ 和 ‘臺中2號’ 表現較佳，視為耐高溫品種；而 ‘初秋’ 、 ‘夏秋’ 、 ‘臺南2號’ 和 ‘大芯’ 表現不佳，為不耐高溫品種。夏作田間於結球初期淹水2天， ‘高峰’ 和 ‘臺南2號’ 葉球重分別為0.27 kg 和0.38 kg，為8品種中顯著最重，視為高溫下耐淹水品種；而 ‘228’ 和 ‘大芯’ 無結球，視為高溫下不耐淹水品種。2015年田間秋作，甘藍結球初期經淹水2天後，其葉球鮮重介於0.6 ~ 0.81 kg，皆較不淹水組0.39 ~ 0.53 kg高，可能淹水處理補足其水份需求。八品種苗株經25℃/20℃淹水2天後，鮮重、乾重、葉面積和壯苗指數之相對生長參數較佳的 ‘臺南2號’ ，其葉片APX活性提升較多，H2O2累積較少，但其餘7品種苗株生長受淹水抑制，與秋作淹水與不淹水後之產量趨勢不符。耐高溫 ‘臺中2號’ 幼苗葉圓片經45℃水浴20 min之細胞膜熱相對傷害值為19.76%，係8品種中顯著最低，而不耐高溫 ‘大芯’ 52.22% 為顯著最高，且8品種之細胞膜熱相對傷害值與夏作葉球重之間呈顯著相關(R = 0.76)；八品種苗株經35℃/30℃處理12 h 之葉片APX相對活性、處理48 h葉綠素、類胡蘿蔔素與MDA之相對含量，以及處理48 h後恢復5天時之相對葉面積，亦與夏作葉球重之間呈顯著相關(p < 0.05)，其相關係數R分別為0.8827、0.8174、0.7786、-0.7658和0.737。而8品種苗株經35℃/30℃淹水48 h 之葉片APX相對活性與夏作淹水後之葉球鮮重間亦呈顯著相關(p < 0.05)；此外，耐高溫淹水 ‘臺南2號’ 葉綠素和類胡蘿蔔素之相對含量顯著高於不耐高溫淹水 ‘大芯’ ；而H2O2相對含量以 ‘臺南2號’ 顯著低於 ‘大芯’ 。綜上，幼苗之葉圓片細胞膜熱相對傷害值以及高溫處理48 h之葉片葉綠素、類胡蘿蔔素和MDA的相對含量可做為篩選耐高溫甘藍之苗期指標，處理高溫12 h和高溫淹水48 h之APX相對活性分別可做為選拔耐高溫和耐高溫淹水甘藍之苗期指標，而葉片葉綠素、類胡蘿蔔素和H2O2之相對含量則可作為選拔耐高溫淹水甘藍之參考，期有助於縮短耐熱及耐高溫淹水甘藍之選育時間。

Cabbage (Brassica oleracea L. var. capitata) is an important leafy vegetable crop in Taiwan. Due to high temperature and rainfall, the cabbage production in Taiwan is limited in summer. Developing high temperature and waterlogging-tolerant cabbage is one of the current goals for the industry. Cabbage ‘228’, ‘Tainan no.2’, ‘Ching-tsui’, ‘KY-cross’, ‘HV-023’, ‘HV-022’, ‘Daishin’ and ‘Taichung no.2’ were used as experimental materials. This study aimed at the utilization of physiological index as chlorophyll fluorescence, photosynthetic pigment, hydrogen peroxide (H2O2), antioxidase including catalase (CAT), ascorbate acid peroxidase (APX) and glutathione reductase (GR), as well as malondialdehyde (MDA) and cell membrane thermostability (CMT) in seedling stage to select tolerant lines. In 2015 summer, according to heading rate and head weight under no waterlogging stress, ‘228’, ‘HV-023’, ‘Ching Tsui’ and ‘Taichung no. 2’ are considered to be heat-tolerant cultivars, while ‘KY cross’, ‘HV-022’, ‘Tainan no. 2’ and ‘Daishin’ are considered to be heat-sensitive cultivars. After 2-days waterlogging treatment in summer, ‘HV-023’ and ‘Tainan no. 2’ showed the heaviest head 0.27 kg and 0.38 kg, respectively and were regarded as waterlogging-tolerant at high temperature. Whereas ‘228’ and ‘Daishin’ showed no heading, thus, were regarded as waterlogging-sensitive at high temperature. In 2015 autumn, the head weights in 8 cabbage cultivars were 0.6~0.81 kg after waterlogging, which were higher than the weight without waterlogging, 0.39~0.53 kg. After waterlogging at 25℃/20℃, ‘Tainan no. 2’, with better relative growth on fresh weight, dry weight, leaf area and seedling index in seedlings, showed the highest APX relative activity and the least H2O2 relative content. The growth of 8 cultivars cabbage was inhibited by waterlogging at 25℃/20℃ in seedling stage, while not in the field in autumn. After water bath at 45℃ for 20 min, heat-tolerant ‘Taichung no. 2’ had the least relative injury (RI) 19.76%, while heat-sensitive ‘Daishin’ had the highest RI 52.22%. The correlation between the RI and the head weight in summer showed high significance (R = 0.76). The correlation of head weight in summer also showed significance (p < 0.05) with the relative activity of APX (R = 0.8827) after treatment for 12 h, the chlorophyll (R = 0.8147), carotenoid (R = 0.7786) and MDA (R = -0.7658) relative content after treatment for 48 h and the relative leaf area after recovery for 5 d (R = 0.737). ‘Tainan no. 2’, tolerant to waterlogging stress at high temperature, also had better performance than high temperature and waterlogging-sensitive ‘Daishin’ in the relative contents of chlorophyll, carotenoid and H2O2 under waterlogging at 35℃/30℃ in seedling stage. In addition, head weight after waterlogging in summer showed significant correlation with APX relative activity after waterlogging for 48 h at 35℃/30℃ in seedling stage. In conclusion, CMT, APX relative activity after 35℃/30℃ treatment for 12 h, the relative content of chlorophyll, carotenoid and MDA after 35℃/30℃ treatment for 48 h can be used as seedling index for selecting heat-tolerant cabbage. APX relative activity after waterlogging at 35℃/30℃ for 48 h can also be applied for selecting waterlogging-tolerant cabbage at high temperature. Besides, chlorophyll, carotenoid and H2O2 relative content might also be a tool to screen the tolerance to waterlogging at high temperature for cabbage. The period for breeding cabbage shall be shortened.