[Responses of Ilex integra Thunb. seedlings to elevated air ozone concentration].
摘要
One-year-old Ilex integra seedlings were exposed to charcoal-filtered (CF) and elevated ozone (E-O3, approximately 150 microL x L(-1)) for 84 days in six open-top chambers. Visible injury, growth parameters, pigments content, gas exchange, chlorophyll a fluorescence and antioxidant system were investigated during the growing season. At the end of experiment, foliage showed remarkable visible symptoms with dark-brown necrotic spots and patches which were concaved on the upper surface of the current-year leaves. Although relative height and diameter increment, total biomass and specific leaf weight (SLW) remained unaffected, E-O3 significantly decreased the percentage of stem biomass in total biomass. E-O3 induced significant decrease in net photosynthetic rate, chlorophyll a/b ratio and total phenolic compound content by 19%, 9% and 36%, respectively. However, stomatal conductance, intercellular CO2 concentration, chlorophyll a fluorescence parameters, pigment contents, MDA contents, total antioxidant capacity and total ascorbate content remained unaffected by E-O3. The results suggested that E-O3-induced change in components of chlorophyll contributed to the reduction of photosynthesis in Ilex integra seedlings. In addition, although visible symptom was found during the experiment, antioxidant system, most of the physiological parameters and growth were not significantly affected by E-O3.