| Summary: | 碩士 === 國立臺灣大學 === 園藝暨景觀學系 === 104 === 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.
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