冷害过程中黄瓜叶片SOD、CAT和POD活性的变化

实验选用3个耐冷力不同的黄瓜品种研究其叶片超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）等3种抗氧化酶活性在冷害过程中的变化。结果表明：低温胁迫期间的CAT和POD活性与黄瓜叶片的耐冷力表现一致，SOD活性则与其耐冷力表现相反。低温胁迫后，3个品种的所有3种抗氧化酶活性均降低，叶片表现出明显的冷害症状，但耐冷力较高的津优10号仍然具有相对较高的CAT活性。恢复期的SOD活性无显著性变化；耐冷力最弱的津研4号和耐冷力中等的津绿3号的CAT活性上升而津优10号的CAT活性降低；3个品种的POD活性都增高，但津研4号的上升幅度明显高于其它2个品种，可能与POD能催化活性氧（ROS）产生有关。

Changes of SOD, CAT and POD Activities in Cucumber Leaves During Cold Damage

Three cucumber cultivars with different cold tolerances were used to study the changes of SOD, CAT and POD activities in Cucumber leaves during cold damage. The results showed that under the stress of low temperature, the cultivars presented the CAT and POD activities in their leaves that were consistent with their cold tolerances but the SOD activity against the cold tolerances. After the stress of low temperature, the three cuhivars presented decreased activities of the three enzymes with the symptoms of cold damage appearing in their leaves, but Junyou 10, a cultivar with high cold tolerance, presented a relatively higher CAT activity. During their recovery period, the cultivars showed an insignificantly varying SOD activity; Junyan 4 with low cold tolerance and Junlu 3 with medium tolerance presented a increased CAT activities while Junyou 10 presented a decreased CAT activities; all the three cuhivars presented increased POD activities but Junyan 4 had a significantly higher POD increment than the other two cultivars did, which might relate to that POD was capable of catalyzing ROS generation.