Differences in the responses of Fraxinus chinensis and Ginkgo biloba seedlings to ozone stress
In order to clarify the stress effects of increasing atmospheric ozone(O3)concentration on the growth,physiological,and biochemical characteristics of woody plants,an open-top chamber(OTC)was used to study the differences in leaf quantity,leaf area,biomass,photosynthetic rate,carbohydrates,and non-structural carbohydrates between typical green plant Chinese ash(Fraxinus chinensis)and ginkgo(Ginkgo biloba)seedlings under three ozone concentrations(environmental concentration,AA;environmental concentration+40 nmol·mol-1,AA+40;environmental concentration+80 nmol·mol-1,AA+80).The results showed that after cumulative fumigation for 35 days,51 days,and 71 days,compared with AA experimental treatment,the leaf number and leaf area growth of the Chinese ash seedlings were inhibited,while the photosynthetic rate of Chinese ash seedlings and the leaf number and leaf area growth of ginkgo seedlings were promoted under AA+40 and AA+80 experimental treatments.The nonstructural carbohydrate content and biomass of Chinese ash and ginkgo seedlings were also inhibited under AA+40 and AA+80 experimental treatments.The leaf growth,photosynthesis rate,and accumulation of unstructured compounds were inhibited in Chinese ash and ginkgo seedlings under elevated O3 concentrations and prolonged ozone fumigation time,but the leaf growth of ginkgo and photosynthesis rate of Chinese ash were promoted by O3 to different degrees.Increases of O3 concentration cause stress on the growth and photosynthesis of Chinese ash and ginkgo seedlings,and the leaf growth state of Chinese ash and the photosynthesis rate of ginkgo show greater sensitivity to O3 stress.