中文摘要：

系统比较欧美杨107杨抗大气SO2污染的无性系和普通欧美杨107杨在抗氧化体系差异,以及它们在生长和气体交换方面对SO2熏气的反应。抗硫无性系表现出显著更强的抗SO2能力。在SO2熏气条件下,抗硫无性系维持较强的光合速率和高存活率。在12mg.m-3SO2浓度下,普通107杨无性系下降了56%,而抗硫无性系的光合速率仅下降了13%。抗硫无性系比普通107杨无性系的SOD活性高出16%,GSH含量高出24%。和普通107杨相比,抗硫无性系气孔明显更大,但气孔密度变小;抗硫无性系叶片的角质层更厚实。结果表明：抗硫无性系中高的SOD活性和GSH含量对减轻SO2的毒害起到重要作用。

英文摘要：

This paper systematically compared variations in antioxidant systems and physiological responses to SO2 fumigation between a SO2-resistant clone of poplar（Populus × euramericana cv.＂74 /76＂） and its ordinary clone.The resistant clone expressed significantly stronger resistance to SO2 than the ordinary clone.Under SO2 fumigation,the resistant clone maintained relative higher net assimilation rate and had higher survival rate in comparison with the ordinary clone.Under 12 mg.m-3 SO2 concentration fumigation,the resistant clone reduced by 13% while the ordinary clone reduced by 56%.The resistant clone had（P 0.01） 16% higher superoxide dismutase（SOD） activity and 24% higher reduced glutathione（GSH） content than the ordinary clone.Moreover,the size of stomata of the resistant clone was larger,with a lower density in comparison with the ordinary clone.The resistant clone had thicker cuticle than the ordinary clone.The results suggested that higher SOD activity and GSH content in the resistant clone played an important role in resisting atmospheric SO2 pollution.