中文摘要：

臭氧和干旱是威胁我国北方城市植物生长的两大重要因素。于2012年利用开顶式气室,通过设置4个处理（AW-大气环境和水分充足;AW＋60-大气增加60 nL/L臭氧＋水分充足;AD-大气＋干旱处理;AD＋60-大气增加60 nL/L臭氧＋干旱处理）,开展了大气臭氧浓度升高（以下简称“臭氧”）和干旱对元宝枫秋季变色期主要色素含量及脱落酸（ABA）含量的影响研究。结果表明：（1）早生叶在臭氧处理后,总叶绿素和类胡萝卜素分别下降了21%和29.6%、花青苷和类黄酮相对含量显著升高了34.1%和7.3%、脱落酸含量增加了19.8%。干旱处理后,早生叶总叶绿素显著下降了18.7%、花青苷和类黄酮相对含量分别显著升高了37%和7.4%、脱落酸含量显著升高了13%。叶片的上述生理变化将会导致叶片提前变红、叶片早衰和提前脱落。（2）晚生叶在干旱处理后总叶绿素含量减少了18.8%,脱落酸含量增加了33.4%,臭氧以及与干旱共同处理未对晚生叶产生显著影响。（3）臭氧和干旱共同处理后,早生叶总叶绿素含量、花青苷和叶片脱落酸含量存在显著交互作用,交互作用缓解了叶片总叶绿素的下降和花青苷的上升,但未缓解叶片脱落酸含量的增加。综上,早生叶和晚生叶对臭氧和干旱处理的响应不同,早生叶对臭氧处理响应大于晚生叶,而晚生叶对干旱更敏感。臭氧和干旱处理均加速了叶片衰老,二者共同处理后叶片脱落风险增加。

英文摘要：

The changing color of leaves in autumn is not only necessary for the growth of foliage trees but is also important for urban landscape interests. Red color in maple leaves relates to the synthesis of anthocyanin and the degraded pigments. Ozone （O3） is an important phytotoxic pollutant, which may affect the basic physiological functions of plants due to its highly reactive oxidative characteristics. The increased consumption of fossil fuels in China has led to increased emission of O3 precursors and visible plant injury induced by high O3 concentration frequently occurs around Beijing. In addition, trees are often subjected to periodic drought in North China with the frequency and the severity of drought events projected in the background of climate change. Drought in summer usually coincides with episodes of high O3 concentrations, which, together, may affect plant growth including color expression and leaf senescence of foliage tree species in fall. Although numerous publications have reported the effects of elevated O3 concentration or drought stress on trees, little is known about the possible interactions between anthocyanin and flavonoid in Asian maple species. To investigate the effects of chronic drought stress and elevated O3 concentrations on leaf pigments and abscission of Shantung maple （Acer truncatum Bunge）, we set up 12 open-top chambers with four treatments （AW： non-filtered ambient air and well watered; AW ＋ 60： non- filtered ambient air plus 60 nL/L O3 and well watered; AD： non-filtered ambient air and drought; AD ＋ 60： non-filtered ambient air plus 60 nL/L O3 and drought） in a suburb of Beijing, China. Total chlorophyll （ total Chl）, carotenoid （ Car）, anthocyanin, flavonoid, and abscisic acid （ABA） contents in early and late-flush leaves were measured in October of the first year. Leaves that unfolded from July 1 to 7 were marked as early-flush leaves and the AOT40 （The cumulative O3 exposure, which was described as the accumulated hourly mean O3 concentra