Five tomato varieties(' 2583','Shenfen 8',' Puhong 909',' Shenfen 998', and ' Fen 2') with various heat tolerances were used as test materials, and changes of antioxidant systems and os-moregulatory substances in their seedling leaves were studied under high temperature (38 °C at daytime and 28 °C at nighOand check temperature(25 °C at daytime and 18 °C at night). The results showed that high temperature made all the seedling leaves' superoxide anion(O2- ? )production rates and ma-londialdehyde(MDA)contents significantly increase,the activities of superoxide dismutase(SOD) ,per-oxidase(POD)and catalase(CAT)increase,and meanwhile the proline and soluble sugar contents accumulate largely. It was also found that the varieties whose increments in antioxidant enzyme activities and osmoregulatory substance contents were larger had lower O2- ? and MDA contents. Thus it can be seen that plants,via osmoregulation and increase of enzyme activity,relieve the damage by high temperature and enhance their own adverse resistance,though there are obvious differences between tomato varieties.%以耐热性不同的5个番茄品种(‘2583’、‘申粉8号’、‘浦红909'、‘申粉998’和‘粉2号’)为试验材料,以昼温25℃/夜温18℃为对照条件,在昼温38℃/夜温28℃高温条件下研究番茄幼苗叶片抗氧化系统及渗透调节物质的变化.结果表明:与对照相比,高温条件下5个品种超氧阴离子(O2-·)产生速率和丙二醛(MDA)含量均显著增加；超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)等抗氧化酶活性均有所升高；同时,脯氨酸和可溶性糖含量也大量积累.渗透调节物质和抗氧化酶活性提高幅度较大的‘粉2号’、‘2583'和‘申粉998’,其体内O2-·和MDA含量均较低.由此可见,不同植物通过渗透调节和酶活性的增加来缓解高温伤害,提高自身的抗逆能力,在不同番茄品种间有明显差异.
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