Abstract:

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.

Key words: poplar (Populus×, euramericana cv. ", 74／76", ), SO₂-resistant clone, antioxidant enzymes, gas exchange, stomatal structure