Abstract: By adding different concentration SO₂ to culture boxes,this paper studied the responses of wheat seedling's superoxide anion radical O2- and antioxidant enzymes to SO₂.The results showed that when the concentration of SO₂ was 10 and 40 μl·L^-1,the O2- content and peroxidase (POD) and catalase(CAT) activities of wheat leaf were increased,while the activity of superoxide dismutase(SOD) was reduced.When the SO₂ concentration was 50 μl·L^-1, the activities of POD and CAT were decreased,with the top end leaves appeared necrosis,and more fungi multiplied on green leaves.Presoaking wheat seeds with 1 mmol·L^-1 salicylic acid (SA) for 6 h or with 10 mmol·L^-1 H₂O₂ for 12 h could efficiently alleviate the oxidative stress caused by SO₂,with the O2- content decreased and the activities of test antioxidant enzymes increased.Under SO₂ fumigation,ethylene significantly inhibited the activities of test enzymes,and promoted the O2- production rate.When applying SA and ethylene at the same time,SA could almost completely eliminate the influences of ethylene on O2- production and test enzyme activities.

Key words: Riec, Roots, Growth and distribution, Root box, Soil compaction