甘藍葉片細胞膜熱穩定度之數學模式化分析

Modeling Thermostability of Cabbage Leaf Cell Membrane

溫室內（日25∕夜18℃）苗齡9週的春秋、初秋、夏峰和大蕊等4個品種甘藍的幼苗，部分移至日32沼[2s·c的溫室內馴化10天，取未馴化和經馴化的葉片以各種熱傷害溫度和時間處理後，測鼠其葉片細胞膜電解質滲漏率，以評估品種間耐熱性之差異。結果為葉片細胞膜電解質滲漏率與熱傷害溫度關係呈S型反應曲線（sigmoid）,以數學模式模擬此反應曲線，發現細胞膜熱傷害的臨界高溫隨著處理時間的增加而下降，葉片經30分鐘的熱傷害處理後，品種間的臨界高溫（Tc）差距不大，未經熱馴化的葉片以50分鐘的熱傷害處理，品種間的臨界高溫（Tc）差距亦不大，但經熱馴化後的品種間的臨界高溫差距變大（l.78°C）•經熱馴化後的葉片經70分鐘的熱惕害處理後，品種間臨界高溫差距更大（2.57°C）。在熱傷害溫度（40-70°C）和時間（30-60分鐘）處理範圍內，經熱馴化處理後其電解質滲漏率比未經熱馴化處理的低，唯夏峰品種經熱馴化和未經熱馴化處理的電解質滲漏率差異小，但經熱馴化後植株細胞膜電解質滲漏率的反應曲面較未經熱馴化處理的增加快，殺傷時間的反應亦同。由本試驗結果得知，未經熱馴化處理時以春秋品種耐熱性最高，其次為夏峰，初秋與大蕊的耐熱性較差，但經熱馴化處理後初秋的耐熱性反而高於夏峰，而且其臨界高溫提高2.79°C最多。

These 9 weeks old pla11ts of cv. K-Y cross, Chuchiu, Hsiafeng, and Tahsin that were raised at day 25/night 18℃ greenhouse, part of pla11ts were shifted to day 32/night 25°C greenhouse for 10 days as preacclimated treatment. The leaf fragments were excised from full expended leaf, then were exposed to various heating temperature (25, 35, 40, 45, 50, 55, 60, and 65°C) for various exposure times (10, 20, 30, 50, 70, 90 min) to measure the leaf cell membrane electrolyte leakages that were the magnitude of thermostability. The sigmoid curves were fitted to the ratio of electrolyte leakage across heating temperatures, then the midpoint temperatures (Tm), were a derivation from mathematic equation. Linear regression was fitted to the midpoint temperature across natural logaritlun of heating times to derive the critical high temperatures (Tc). Finally the graphic presentation of interactions of heating temperatures and exposing times on the electrolyte leakage was modeled The results showed that Tc decreased with increased exposing times of heating treatments. The acclimated pla11ts appeared higher critical high temperature than unacclimated pants, therefore the acclimated pla11ts could increase the heat tolera11t ability. The critical high temperatures of the unacclimated plants of cv. K-Y cross血Hsiafeng were higher than others, in contrast, the acclimated plants of 'Chuchiu' was increased 2.7°C to result in more heat tolerance than 'Hsiafeng'. It is concluded that 'K-Y cross' and 'Chuchiu'were much heat tolerance, and latter one had the best ability to acquire heat tolerai1ce through acclimation.