水分胁迫下自由基清除剂对番木瓜的生理保护效应

用维他命C(Vc)、维他命E(VE)和苯甲酸钠等作为外源自由基清除剂在水分胁迫前1d预处理番木瓜幼苗，研究其对番木瓜的生理保护效应。结果表明，3种外源自由基清除剂预处理有效地降低了水分胁迫下番木瓜叶片细胞质膜透性、POD活性、MDA和H2O2含量的上升程度，并能延缓叶片叶绿素和可溶性蛋白质含量和SOD活性的降低。外源自由基清除剂通过有效清除H2O2降低膜脂过氧化程度，从而减轻水分胁迫对番木瓜引起的自由基伤害和提高番木瓜的抗旱能力。不同自由基清除剂预处理对番木瓜的抗旱保护效果存在差异，其中以Vc预处理的保护效果最好。

Physiological Protective Effect of Free Radical Scavenger on Papaya under Water Stress

The leaves of Carica papaya seedlings cultured in pots were sprayed on both surfaces with free radical scavengers, i.e. vitamins C (10 mmol/L), E (6 mmol/L) and sodium benzoate (5 mmol/L), respectively one daybefore water stress treatment. Soil in pots was dried naturally to 12%-14% of moisture content, whereas forcontrol at 60%-65%. The results showed that the pretreatment with free radical scavengers could effectivelydecrease the increment level of plasma membrane permeability , POD activity , MDA and H2O2 contents,retard the decrease of chlorophyll and soluble protein contents and the SOD activity in papaya under water stress. Among the free radical scavengers, the protective effect of vitamin C was best.