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Objective:To study the oxidative stress and antioxidative response of Cinnamomum camphora seedlings exposed to nitrogen dioxide (NO2) fumigation.Methods:Measurements were made up of the growth,chlorophyll content,chlorophyll fluorescence,antioxidant system and lipid peroxidation of one-year-old C.camphora seedlings exposed to NO2 (0.1,0.5,and 4 μl/L) fumigation in open top chambers over a period of 60 d.Results:After the first 30 d,0.5 and 4.0 μl/L NO2 showed insignificant effects on the growth of C.camphora seedlings.However,exposure to 0.5 and 4.0 μl/L NO2 for 15 d significantly reduced their chlorophyll content (P<0.05),enhanced their malondialdehyde (MDA) content and superoxide dismutase (SOD) activity (P<0.05),and also significantly reduced the maximal quantum yield of PSII in the dark [the ratio of variable fluorescence to maximal fluorescence (Fv/Fm)] (P<0.05).In the latter 30 d,0.5 μl/L NO2 showed a positive effect on the vitality of the seedlings,which was reflected by a recovery in the ratio of Fv/Fm and chlorophyll content,and obviously enhanced growth,SOD activity,ascorbate (AsA) content and glutathione reductase (GR) activity (P<0.05);4.0 μl/L NO2 then showed a negative effect,indicated by significant reductions in chlorophyll content and the ratio of Fv/Fm,and inhibited growth (P<0.05).Conclusion:The results suggest adaptation of C.camphora seedlings to 60-d exposure to 0.1 and 0.5 μl/L NO2,but not to 60-d exposure to 4.0 μl/L NO2.C.camphora seedlings may protect themselves from injury by strengthening their antioxidant system in response to NO2-induced oxidative stress.
Objective: To study the oxidative stress and antioxidant response of Cinnamomum camphora seedlings exposed to nitrogen dioxide (NO2) fumigation. Methods: Measurements made made of of growth, chlorophyll content, chlorophyll fluorescence, antioxidant system and lipid peroxidation of one-year-old Results: After the first 30 d, 0.5 and 4.0 μL / L NO2 showed insignificant effects on the growth of C. camphora seedlings.Wowever, exposure to 0.5 and 4.0 μl / L NO2 significantly reduced their chlorophyll content (P <0.05), enhanced their malondialdehyde (MDA) content and superoxide dismutase (SOD) activity ), and also significantly reduced the maximal quantum yield of PSII in the dark [the ratio of variable fluorescence to maximal fluorescence (Fv / Fm)] .In the latter 30 d, 0.5 μl / L NO2 showed a positive effect on the vitality of the seedlings, which was reflected by ar ecovery in the ratio of Fv / Fm and chlorophyll content, and obviously enhanced growth, SOD activity, ascorbate (AsA) content and glutathione reductase (GR) activity by significant reductions in chlorophyll content and the ratio of Fv / Fm, and inhibited growth (P <0.05). Conlusion: The results suggest adaptation of C. camphora seedlings to 60-d exposure to 0.1 and 0.5 μl / L NO2, but not to 60-d exposure to 4.0 μl / L NO2. C. camphora seedlings may protect themselves from injury by strengthening their antioxidant system in response to NO2-induced oxidative stress.