全缘冬青幼苗(Ilex integra Thunb.)对大气O_3浓度升高的响应

Responses of Ilex integra Thunb. Seedlings to Elevated Air Ozone Concentration

采用开顶式气室(open top chambers,OTCs)装置,研究O3浓度升高(E-O3,约150μL.L-1)对常绿阔叶树种全缘冬青幼苗的影响,主要包括伤害症状、植株生长、光合色素含量、气体交换速率与叶绿素荧光、丙二醛含量以及主要抗氧化剂含量变化.经过高浓度O3处理一个生长季后,当年生全展叶片表面分布着大量的黑褐色斑点与斑块,呈腐蚀状凹陷于叶片表面.O3引起茎百分比显著降低7%,但对株高与基径生长、生物量累积与比叶重无显著性影响;与CF处理相比,O3处理下全缘冬青幼苗当年生全展叶片净光合速率、叶绿素a/b值与总酚含量分别显著降低19%、9%与36%.气孔导度、胞间CO2浓度、叶绿素荧光参数、光合色素含量、叶片丙二醛含量、总还原能力以及抗坏血酸含量的变化均不显著.结果表明,O3对全缘冬青幼苗的光合作用具有一定的抑制作用,叶绿素含量组成发生变化是引起净光合速率下降的主要原因;O3对植株总的抗氧化能力未产生明显影响,尚未引起膜脂过氧化程度加剧;虽然全缘冬青幼苗叶片呈现伤害症状,但植株生长指标未受到O3的显著影响.

One-year-old Ilex integra seedlings were exposed to charcoal-filtered（CF） and elevated ozone（E-O3,～150 μL·L-1） for 84 days in six open-top chambers.Visible injury,growth parameters,pigments content,gas exchange,chlorophyll a fluorescence and antioxidant system were investigated during the growing season.At the end of experiment,foliage showed remarkable visible symptoms with dark-brown necrotic spots and patches which were concaved on the upper surface of the current-year leaves.Although relative height and diameter increment,total biomass and specific leaf weight（SLW） remained unaffected,E-O3 significantly decreased the percentage of stem biomass in total biomass.E-O3 induced significant decrease in net photosynthetic rate,chlorophyll a/b ratio and total phenolic compound content by 19%,9% and 36%,respectively.However,stomatal conductance,intercellular CO2 concentration,chlorophyll a fluorescence parameters,pigment contents,MDA contents,total antioxidant capacity and total ascorbate content remained unaffected by E-O3.The results suggested that E-O3-induced change in components of chlorophyll contributed to the reduction of photosynthesis in Ilex integra seedlings.In addition,although visible symptom was found during the experiment,antioxidant system,most of the physiological parameters and growth were not significantly affected by E-O3.