水杨酸对高温胁迫下黄瓜幼苗光合特性和过氧化物酶活性的影响

目的]研究外施水杨酸( SA)对黄瓜幼苗抗高温胁迫能力的生理效应。方法]以“津春3号”黄瓜幼苗为试验材料，对其喷施浓度分别为0.05、0.10和0.50 mmol/L的SA溶液，并进行昼(40±1)℃/夜(30±1)℃高温胁迫处理，研究黄瓜幼苗4叶期叶片光合特性、叶绿素荧光参数变化及过氧化物酶(POD)活性。结果]高温胁迫下幼苗叶片的净光合速率(Pn)、羧化效率(CE)、表观量子效率(AQY)、光化学淬灭系数(qP)、PSⅡ实际光化学效率(фPSⅡ)、POD活性明显降低，而幼苗叶片初始荧光(Fo)、非光化学淬灭系数(NPQ)明显增加，且嫁接苗的变化趋势弱于自根苗。结论]不同浓度的SA溶液均可抑制高温胁迫下黄瓜幼苗Pn、CE、AQY、qP、фPSⅡ、POD活性的降低和Fo、NPQ的增加，以浓度为0.10 mmol/L的SA处理效果最优。

Effect of Salicylic Acid on the Photosynthetic Characteristics and Peroxide Enzyme Activity of Cucumber Seedlings under the Stress of High Temperature

Objective] The effect of exogenous salicylic acid ( SA) on the physiological reaction of cucumber seedling under the high stress temperature was studied. Method] The testing material:cucumber variety"Jinchun 3" seedlings, was treated with the salicylic acid with the concentration of 0. 05, 0. 10 and 0. 50 mmol/L and the stress of high temperature of (40 ± 1) ℃ in day and (30 ± 1) ℃ in night. The photo-synthetic characteristics, the variation of chlorophyll fluorescence parameters and peroxidase activity of cucumber plant at 4 leaves were tested. Results] The net photosynthetic rate ( Pn) , carboxylation efficiency ( CE) , apparent quantum efficiency ( AQY) , photochemical quenching ( qP) , PSⅡ actual photochemical efficiency (фPSⅡ) , POD activity in the laef of seedlings under the stress of high temperature were signifi-cantly reduced;while the initial fluorescence ( Fo) and non-photochemical quenching ( NPQ) , significantly increased. And the trend of the value of those indicators of grafted seedlings was weaker than self-rooting seedlings. Conclusion] All SA solutions could reduce the activities of Pn, CE, AQY, qP,фPSⅡ,POD and increase Fo and NPQ in the cucumber seedlings under the stress of high temperature and the SA with the concentration of 0. 10 mmol/L is the best treatment.