Effect of short-term daytime sub-high temperature on antioxidant enzymes of tomato leaves | 短期昼间亚高温对番茄叶片抗氧化酶活性的影响

صينى. 为探讨短期昼间亚高温对番茄叶片光合作用产生影响的原因，以昼温25℃为对照，在番茄第1花序第1花开花当天开始进行为期9d的35℃昼间亚高温处理，分析短期昼间亚高温对番茄叶片净光合速率、叶绿素含量和抗氧化酶活性的影响。结果表明：短期35℃昼间亚高温处理明显降低了番茄叶片的净光合速率和叶绿素含量，在处理结束时分别比对照降低了26．27％和33．07％。亚高温对抗氧化酶活性的影响不尽相同，其中CAT的活性始终低于对照，而SOD和POD活性则呈现先升高后降低的趋势，亚高温处理前3d高于对照，处理时间延长至6d以上则低于对照。在处理结束时SOD、POD和CAT的活性分别比对照降低了18．28％、22．28％和15．12％。亚高温处理后MDA含量大幅增加，始终高于对照。可见，短期昼间亚高温胁迫会使番茄叶片光合能力降低、光合色素降解．这主要是因为叶片中抗氧化酶活性降低，活性氧大量增加，导致叶片膜脂过氧化作用加重，活性氧在细胞内的积累使得细胞膜系统和光合机构受到伤害。[著者文摘]

إنجليزي. In order to investigate the reason that daytime sub-high temperature influences photosynthesis of tomato leaves. The tomatoes were treated with daytime sub-high temperature （35℃） for 9 days during the 1st inflorescence flowering, 25℃ as control. The effects of sub-high temperature on net photosynthetic rate, chlorophyll content and activities of antioxidant enzymes of tomato leaves were studied. The results showed that： short-term sub-high temperature （35℃） treatment significantly reduced the net photosynthetic rate and chlorophyll content, at the end of the treatment, the net photosynthetic rate and chlorophyll content were lower than control for 26.27% and 33.07% respectively. The effects of sub-high temperature （35℃） on the activities of antioxidant enzymes were not the same, the activity of CAT was lower than control throughout. The activities of SOD and POD were increased at first and then decreased, when treated for 3 days, the activities of SOD and POD were higher than control, when treated for more than 6 days, the activities of SOD and POD were reduced. At the end of the treatment, the activities of SOD, POD and CAT were lower than control for 18.28%, 22.28% and 15.12% respectively. Short-term sub-high temperature （35℃） increased content of MDA, the content of MDA was higher than control throughout. The results indicated that Short-term sub-high temperature（35℃）could reduce photosynthetic ability of tomato leaves, lead to degradation of photosynthetic pigment, this is due to the activities of antioxidant enzymes are decreased which lead to aggravation of membrance lipid peroxidation, accumulation of active oxygen lead to the damages of cell membrane system and photosynthetic mechanism.