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采用开顶式气室(open top chambers,OTCs)装置,研究O3浓度增加(E-O3,约150 nL.L-1)对湿地松幼苗的影响,包括伤害症状、植株生长、针叶光合色素含量、气体交换速率与叶绿素荧光、丙二醛(MDA)以及主要抗氧化剂含量变化.经过E-O3处理一个生长季后(AOT40值为38.24μL.L-1.h),湿地松幼苗当年生新叶与老叶呈现出伤害症状,而株高与基径生长、生物量累积与分配未出现显著变化;与对照相比,O3暴露对当年生针叶光合作用具有一定的抑制作用:净光合速率(Pn)、气孔导度(gs)与蒸腾速率(Tr)分别显著降低42.5%、48.2%与46.3%,而胞间CO2浓度(ci)与水分利用效率(WUE)、叶绿素荧光指标无显著变化;叶绿素a、叶绿素b与总叶绿素含量分别降低16.7%、21.1%与17.5%,叶片MDA含量、总还原能力、抗坏血酸与总酚含量均无显著变化.可见,光合色素含量的降低是E-O3引起湿地松幼苗针叶光合速率下降的主要原因.
The effect of O3 concentration (E-O3, about 150 nL.L-1) on the seedlings of P. elliottii was investigated using open top chambers (OTCs), including injury symptoms, plant growth, Content, gas exchange rate and chlorophyll fluorescence, malondialdehyde (MDA) content and main antioxidants content.After E-O3 treatment of a growing season (AOT40 value of 38.24μL.L-1.h), Slash pine New leaves and old leaves showed symptoms of injury, while plant height and base diameter did not show significant changes in biomass accumulation and distribution. Compared with the control, O3 exposure had some inhibitory effects on the photosynthesis of the annual needle: net photosynthesis (Pn), stomatal conductance (Gs) and transpiration rate (Tr) decreased by 42.5%, 48.2% and 46.3%, respectively. However, there were no significant differences in ci, WUE and chlorophyll fluorescence The contents of chlorophyll a, chlorophyll b and total chlorophyll decreased by 16.7%, 21.1% and 17.5%, respectively, and there was no significant change in MDA content, total reductive capacity, ascorbic acid and total phenolic content in leaves.It can be seen that the decrease of photosynthetic pigment content is E- O3 causes the decrease of needle photosynthesis of Pinus elliottii seedlings.