中文摘要：

以‘章丘大葱’为对照，研究了25-50℃下耐热大葱品种‘春味’、‘吉叶晚抽’和‘长悦’叶片丙二醛含量，电解质外渗率，叶绿素荧光参数和抗氧化酶活性的变化。结果表明，高温下耐热大葱品种叶片光系统II（PSII）最大光化学效率的下降和电解质外渗率的增加幅度小于章丘大葱，说明耐热大葱品种PSII和细胞膜热稳定性高于章丘大葱。高温下，3个耐热大葱品种和章丘大葱叶片超氧化物歧化酶（SOD）、过氧化物酶（CAT）、抗坏血酸过氧化物酶（APX）活性上升，但耐热品种上升幅度显著高于章丘大葱，表明其叶片抗氧化能力较高。因此，耐热大葱品种叶片较高的抗氧化酶活性是其耐热性较强的原因之一。

英文摘要：

Using‘ Zhangqiu Dacong＇ scallion as control, changes of malondialdehyde （ MDA ） content, electrolyte leakage, chlorophyll fluorescence parameters and antioxidant enzyme activities were studied in leaves of heattolerant scallion, ＇Chunwei＇, ＇Jiye Wanchou＇ And ＇Changyue＇, at 25 - 50 ℃. The results showed that the extent of decrease in the maximum photochemical efficiency of photosystem II and of the increase in electrolyte leakage in leaves of the heat tolerant scallion was less than that in leaves of the ＇Zhangqiu Dacong＇ scallion at high temperature, indicating that the thermostability of photosystem II and cell membrane was higher in the heattolerant scallion than that in the ‘Zhangqiu Dacong＇ scallion. At hightemperature, the activities of superoxide dismutase （SOD）, catalase （CAT） and ascorbate peroxidase （APX） increased in leaves of the heattolerant scallion and ＇Zhangqiu Dacong＇ scallion, but the increase extent was greater in the summer scallion, which suggests that heattolerant scallion had a higher antioxidant capacity than the ＇Zhangqiu Dacong＇ scallion did. Having higher antioxidant ability is one of the reasons for higher heat tolerance in the leaves of heattolerant scallion.