CO_2和O_3浓度升高及其复合作用对华山松生长及光合日变化的影响

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.

Effects of Elevated CO2 or/and O3 on Growth and Daily Changes of Photosynthesis in Leaves of Pinus armandi

To study the responses of growth and daily changes of photosynthesis in leaves of Pinus armandi to elevated O_3,elevated CO_2 and elevated O_3+CO_2in 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 O_3 and elevated O_3+elevated CO_2for a growing season,and the growth(fresh weight,dry weight,leaf length,axial shoot,lateral shoot),daily changes and diurnal assimilation amounts of Pi...