本研究探討外施鈣對於乾旱逆境甘藷葉片抗氧化系統之影響，以甘藷’桃園2號’、’西蒙1號’與’徐藷18號’為供試材料，外施0、60、120與180 kg/ha CaCl2後，做乾旱與正常供水（控制組）處理，採逢機完全區集、裂裂區設計，3重複。結果顯示，外施60、120 kg/ha CaCl2顯著促進乾旱處理之甘藷葉片抗氧化酵素與抗氧化物，但180kg/haCaCl2則減少某些抗氧化酵素與抗氧化物。乾旱逆境下甘藷葉片之抗氧化系統與預處理鈣有關，可能乾旱逆境時植物細胞經由Ca2流反應，增高GR活性及還原態ASA、ASA、總ASA與GSH含量；缺水逆境下，鈣對於抗氧化系統具重要増進功能，適當的鈣濃度可使葉片恢復所受之氧化傷害；此結果亦可解釋’徐藷18號’比’桃園2號’與’西蒙1號’更耐旱。
The leaf antioxidative system of water-stressed sweet potato was studied through exogenous calcium treating. Sweet potato 'Taoyuan 2', 'Simon 1', and 'Sushu 18' pre-applied with 0, 60, 120 and 180 kg/ha CaCl2 were given drought stress, and plants with non-drought condition were taken as control. A split-split plot design in randomized complete blocks with three replications was used. The values of all antioxidases and antioxidants in the sweet potatoes were significantly enhanced by drought following 60 and 120 kg/ha Ca^(+2) addition. However, pre-applying 180 kg/ha CaCl2 markedly reduced the amounts of some enzymes and antioxidants. Different varieties displayed variations in their oxidative system, and the differential expressions of each genotype were associated with drough stress response. The antioxidative system level in leaves of sweet potato under drought stress was related to its calcium pre-treatment. The plant cells may respond to water stress with Ca^(+2) flux and resulting increased GR activities, and reduced ASA, ASA, total ASA and GSH contents which provide increased drought tolerance. Calcium exhibited an important function in the antioxidative system under water-deficit stress. Optimum concentration of calcium can restore leaf oxidative damage. The results help explain why 'Sushu 18' is more resistant to drought than 'Taoyuan 2' and 'Simon 1'.
