State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing Road 18, Haidian District, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing Road 18, Haidian District, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2017 Dec 15;603-604:185-195. doi: 10.1016/j.scitotenv.2017.06.083. Epub 2017 Jun 15.
Poplar clones 546 (P. deltoides cv. '55/56'×P. deltoides cv. 'Imperial') and 107 (P. euramericana cv. '74/76') were exposed to five ozone concentrations in 15 open-top chambers (OTCs). Both ozone exposure (AOT40, Accumulation Over a Threshold hourly ozone concentration of 40ppb) and flux-based (POD, Phytotoxic Ozone Dose above an hourly flux threshold of 7nmol O m PLA (projected leaf area) s) response relationships were established with photosynthesis, leaf morphology and biomass variables. Increases in both metrics showed significant negative relationships with light-saturated photosynthesis rate, chlorophyll content, leaf mass per area, actual photochemical efficiency of PSII in the light and root biomass but not with stomatal conductance (g), leaf and stem biomass. Ozone had a greater impact on belowground than on aboveground biomass. The ranking of these indicators from higher to lower sensitivity to ozone was: photosynthetic parameters, morphological index, and biomass. Clone 546 had a higher sensitivity to ozone than clone 107. The coefficients of determination (R) were similar between exposure- and flux-based dose-response relationships for each variable. The critical levels (CLs) for a 5% reduction in total biomass for the two poplar clones were 14.8ppmh for AOT40 and 9.8mmol O m PLA for POD. In comparison, equivalent reduction occurred at much lower values in photosynthetic parameters (4ppmh for AOT40 and 3mmol O m PLA for POD) and LMA (5.8ppmh for AOT40 and 4mmol O m PLA for POD). While in recent decades different CLs have been proposed for several plant receptors especially in Europe, studies focusing on both flux-based dose-response relationships and CLs are still scarce in Asia. This study is therefore valuable for regional O risk assessment in Asia.
白杨无性系 546（杂交杨 55/56×杂交杨 帝国）和 107（欧美杨 74/76）在 15 个开顶式气室（OTC）中暴露于五种臭氧浓度下。用光合作用、叶片形态和生物量变量建立了臭氧暴露（AOT40，臭氧浓度 40ppb 小时阈值以上的累积）和通量基础（POD，7nmol O m PLA（预计叶面积）s 小时通量阈值以上的光化学臭氧剂量）的响应关系。这两个指标的增加均与光饱和光合作用速率、叶绿素含量、叶面积比、光下 PSII 的实际光化学效率和根生物量呈显著负相关，但与气孔导度（g）、叶和茎生物量无关。臭氧对地下生物量的影响大于地上生物量。这些指标对臭氧敏感性从高到低的排序为：光合参数、形态指标和生物量。无性系 546 对臭氧的敏感性高于无性系 107。每个变量的暴露和通量基础剂量反应关系的决定系数（R）相似。两个杨树无性系总生物量降低 5%的临界水平（CL）分别为 AOT40 的 14.8ppmh 和 POD 的 9.8mmol O m PLA。相比之下，在光合作用参数（AOT40 的 4ppmh 和 POD 的 3mmol O m PLA）和 LMA（AOT40 的 5.8ppmh 和 POD 的 4mmol O m PLA）中，等效减少发生在低得多的值。虽然在最近几十年，特别是在欧洲，针对几种植物受体提出了不同的 CL，但在亚洲，关于通量基础剂量反应关系和 CL 的研究仍然很少。因此，本研究对于亚洲区域臭氧风险评估具有重要价值。
