不同耐热性小麦品种旗叶膜脂过氧化和保护酶活性对花后高温胁迫的响应

以2个耐热性不同的冬小麦品种山农1391和藁城8901为材料，用塑料薄膜制成增温棚，分别于花后8~10 d (T1)和花后15~17 d (T2)进行高温处理，研究了花后不同时期高温胁迫对小麦旗叶丙二醛(MDA)含量、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性的影响。结果表明，T1处理的旗叶内活性氧防卫系统能更有效地启动，使膜脂过氧化水平有所下降，而T2处理造成的伤害不可恢复。花后28 d，与藁城8901相比，山农1391各处理MDA含量较低。T1处理的SOD和CAT活性明显上升，但CAT活性的上升期晚于SOD，它们协同起保护作用，延缓旗叶的衰老，其中山农1391SOD活性的上升幅度较大，而且CAT活性的恢复性增加的能力较强；T2处理的SOD活性未见上升，甚至有所下降，CAT活性虽然高于对照，却未能有效减轻膜脂过氧化程度，表明SOD在酶保护系统中起核心作用。T1处理降低了POD清除H₂O₂的能力；T2处理的POD活性大幅上升，可能对叶片起到了伤害作用，加速了旗叶的衰老。因此，小麦的耐热性随花后生育进程而下降，应特别加强灌浆中后期的田间管理，减轻高温的伤害。

Response of Flag Leaf Lipid Peroxidation and Protective Enzyme Activity of Wheat Cultivars with Different Heat Tolerance to High Temperature Stress after Anthesis

In order to elucidate the antioxidation mechanism of wheat subjected to post-anthesis high temperature stress,changes of MDA content and protective enzyme activity under high temperature stress at different grain filling stages were studied by using two different heat-tolerance winter wheat(Triticum aestivum L.) cultivars SN1391 and GC8901.High temperature stresses were made from the 8th to 10th day after anthesis(T1) and from the 15th to 17th day after anthesis(T2) respectively by plastic sheds.Antioxidant system in flag leaf could be more efficiently operated in T1 to reduce lipid peroxidation,while the injury of T2 couldn't be recovered.In T1,the activity of SOD and CAT significantly increased,the increasing time of CAT was later than that of SOD,the two enzymes cooperated with each other so that they could retard the senescence of flag leaf.On the 28th day after anthesis,the MDA content of SN1391 was lower than that of GC8901 in corresponding treatment.The SOD activity increasing extent of SN1391 was much bigger than that of GC8901,and the recovery capability of CAT activity was greater in SN1391 than in GC8901.In T2,the activity of SOD decreased.Although the activity of CAT was higher than that of CK,it couldn't abate the degree of flag leaf lipid peroxidation efficiently.This indicated that SOD played an essential role in protective enzyme system.The ability of POD eliminating H_2O_2 was diminished in T1 and the activity of POD significantly increased in T2,which probably damaged the leaves and accelerated their senescence.According to the results above we concluded that with the post-anthesis development,the wheat heat tolerance is deteriorated,so field management should be enhanced especially in middle and late grain filling stages in order to ease the injury of high temperature stress.