結球白菜與小白菜葉片細胞膜熱穩定性之數學模式化分析

Modeling Leaf Cell Membrane Thermostability of Chinese Cabbage and Pak-choi

25/18℃（日／夜溫）溫室內培育之苗齡9週的‘錦秋’、‘亞蔬一號’和‘農友一號’等3個品種之結球白菜幼苗及苗齡2週的‘臺農一號’之小白菜幼苗，將其一部分移至32/25℃（日／夜溫）的溫室內馴化10天。取未馴化及經馴化的葉片以不同熱傷害溫度和熱傷害時間處理後，測量其葉片細胞膜電解質滲漏率，以評估品種間耐熱性之差異。試驗結果顯示葉片細胞膜電解質滲漏率與熱傷害溫度間之關係呈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溫度（Tc）隨著處理時間的增加而下降。‘錦秋’、‘亞蔬一號’、‘農友一號’和‘臺農一號’等四個白菜品種經熱馴化處理後，其臨界溫度比未經熱馴化處理者，分別提高1.21～1.55、0.03～0.48、1.80～3.07、0.28～3.08℃。未經熱馴化處理之臨界溫度以‘亞蔬一號’最高而‘臺農一號’最低，經熱馴化處理後以‘農友一號’其臨界高溫最高，‘臺農一號’最低。由本試驗結果得知，未經熱馴化處理的耐高溫能力以‘亞蔬一號’最佳，其次為‘錦秋’、‘農友一號’，‘臺農一號’耐熱性最差，但經熱馴化處理後‘農友一號’耐熱性略高於‘亞蔬一號’，具有最高的耐熱潛力。

Nine weeks old plants of chinses cabbage cvs. 'Jiinchiou', 'ASVEG No.1', and 'Knowyou No.1'and 2 weeks old plants of 'Tainung No.1' were grown in 25/18℃ (day/night) greenhouse. Part of plants were shifted to 32 day / 25℃ night greenhouse for 10 days as acclimation treatment. The leaf fragments were excised from full expended leaves, then were exposed to various heating temperature for various exposure times to measure the leaf cell membrane electrolyte leakage that were the degrees of thermostability. The sigmoid curves were fitted to the electrolyte leakage ratios across heating temperatures, then the midpoint temperature (Tm), were a derivation from the modeling mathematic equation. Linear regression was fitted to the midpoint temperature across natural logarithm of heating time to derivation the critical high temperature (Tc). Finally the graphic presentation of interaction of critical high temperatures and exposing times on the electrolyte leakage was modeled. The results showed that Tc decreased with the increased exposing time of heating treatment. The Tcs of acclimated plants of 'Jiinchiou', 'ASVEG No.1', 'Knowyou No.1'and 'Tainung No.1' were higher (1.21~1.55, 0.13~0.48, 1.8~3.07, 0.28~3.08 ℃ ) than unacclimated plant, respectively. The 'ASVEG No.1' showed the highest Tc among unacclinated plants. However, the 'Knowyou No.1' appeared the highest Tc among acclimated plants. It is concluded that 'Knowyou No. 1' has the best thermostability due to it is able to acquire the highest heat tolerance by acclimation in hot greenhouse.