中文摘要：

以生长在沈阳市区内的5年生华山松幼树为实验材料,采用开顶箱法,研究高浓度CO2和高浓度O3下华山松生长变化、光合速率的日变化动态以及日光合总量季节变化,进而了解大气CO2浓度升高、O3浓度升高及其复合作用对华山松光合作用及生长的影响.结果表明,①高浓度O3处理后,华山松20～90 d针叶鲜重、干重增长量以及90 d针叶叶长较对照分别降低45.8%、38.9%和15.3%.主侧枝生长与对照相比无显著差异.高浓度O3降低了华山松日光合总量,处理30 d后,针叶净光合速率均显著低于对照,光合速率日变化曲线表现为双峰型,光合＂午休＂程度强于对照.②高浓度CO2处理后,华山松针叶鲜重、干重20～90 d增长量分别高于对照41.7%和22.2%,而针叶叶长以及主侧枝长未受显著影响.华山松日光合总量高于对照处理,处理30 d、60 d时,净光合速率普遍高于对照.CO2处理90 d时,日变化曲线由双峰变为单峰曲线,极大缓解了光合＂午休＂现象.③高浓度O3和CO2复合处理后,针叶干重、鲜重增量均低于对照,表明了复合处理后O3伤害的发生,但针叶干重高于O3单因子处理,这表明高浓度CO2可以一定程度上缓解高.浓度O3对华山松针叶生长的抑制作用.针叶叶长,主侧枝生长未见明显效应.复合处理后,针叶净光合速率普遍低于对照,华山松日光合总量低于对照而高于O3单独处理,说明高浓度CO2可以通过减缓O3对植物光合的抑制而减少O3伤害.光合速率日变化曲线表现为双峰型.

英文摘要：

To study the responses of growth and daily changes of photosynthesis in leaves of Pinus armandi to elevated O3,elevated CO2 and elevated O3＋CO2 in urban area,experiment was conducted in Shenyang Arboretum located at the center of the city.Five-year-old trees grown in open-top chambers（OTC） were exposed to control,elevated O3 and elevated O3＋elevated CO2 for a growing season,and the growth（fresh weight,dry weight,leaf length,axial shoot,lateral shoot）,daily changes and diurnal assimilation amounts of Pinus armandi leaves were measured.The results showed that ① the increments of fresh weight and dry weight in 70 days were reduced 45.8% and 38.9% by elevated O3 compared to the control.After 90 days,leaf length decreased 15.3%,but there were no significant difference detected in axial shoot and lateral shoot compared to the control.Diurnal assimilation amounts were decreased in elevated O3 treatment,and after 30 days exposure,net photosynthesis rate（Pn） of leaves was decreased significantly compared to the control.Under O3 exposure,the diurnal pattern of net photosynthetic rate curve was two peaks,and a midday depression at noon was lower than control.② Under elevated CO2 exposure,the increments of fresh weight and dry weight in 70 days were increased 41.7% and 22.2%,but leaf length,axial shoot and lateral shoot after 90days were not changed compared to control.Diurnal assimilation amounts were increased after elevated CO2 exposure in total,and in 30 and 60 days,net photosynthesis rates（Pn） of leaves were higher than that of control mostly.From diurnal variation of Pn,the diurnal pattern of net photosynthetic rate curves of Pinus armandi leaf was changed from two-peaks to one-peak curue after 90 days elevated CO2 exposure,that means the midday depression was relieved by high CO2.③ When trees were exposed to both elevated O3 and elevated CO2,the increments of fresh weight and dry weight in 70 days were all decreased compared to the control,which indicates that season-long exposure to elevated