title: Impacts of elevated ozone on growth and photosynthesis of Metasequoia glyptostroboides Hu et Cheng.
abstract: One-year-old Metasequoia glyptostroboides seedlings were exposed to non-filtered ambient air (NF) and elevated ozone (E-O3, NF+60 ppb) in open-top chambers for two years. E-O3 accelerated leaf senescence, as indicated by significant decreases in photosynthetic pigment contents with the elongation of O3 exposure. E-O3 significantly affected gas exchange and carboxylation, inducing reductions in light-saturated photosynthesis (Asat), the maximum activity of Rubisco (Vc,max) and the maximum electron transport rate (Jmax). Chl a/b, Vc,max/Jmax and stomatal limitation (l) were not affected. Stomatal conductance (gs) was significantly decreased by E-O3 in the first year, but remained unchanged in the second year. It can be inferred that the decrease in Asat by E-O3 was mainly attributed to the changes in non-stomatal factors. After two years' exposure, E-O3 caused significant decreases in canopy photosynthesis and leaf mass per area, and a significant increase in the number of branches, but induced slight, not significant decreases in growth and biomass. Therefore, it can be concluded that the carbon accumulation of the species M. glyptostroboides could be negatively affected after long-term exposure to high O3 concentration.
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China; Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin 150081, China.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China. Electronic address: zhzhfeng201@hotmail.com.
authors.forename: Zhaozhong
authors.initials: Z
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China.
authors.forename: Xiaoke
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China.
authors.forename: Junfeng
authors.initials: J
authors.lastname: Niu
mesh_terms: D029779:Cupressaceae / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D010126:Ozone / Q000009:adverse effects*; D010788:Photosynthesis / Q000187:drug effects*; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism
chemical_list: D010126:Ozone
keywords: Growth; Living fossil species; Metasequoia glyptostroboides; Ozone; Photosynthesis