臭氧胁迫对香樟幼苗光合生理特性的影响

Impact of ozone stress on photosynthetic characteristics of Cinnamomum camphora seedlings

探讨对流层臭氧对植物生长的影响及其机制,以期为城市环境可持续发展提供科学依据。采用开顶箱气室(OTC)模拟熏蒸法,探讨了高浓度臭氧对长沙地区典型城市林木——香樟(Cinnamomum camphora)幼苗光合特性的影响。结果表明:臭氧胁迫对香樟幼苗的生长产生了显著的抑制作用,株高和地径均呈现下降趋势;此外,臭氧处理导致香樟叶片受到显著伤害。经过两个月的臭氧胁迫,香樟叶片的叶绿素a(Chla)、叶绿素b(Chlb)和类胡萝卜素(Car)含量较对照组NF分别下降了20.0%~63.1%、8.2%~34.7%、15.7%~62.5%,光合色素含量明显减少。香樟叶片的净光合速率(P_(n))、气孔导度(G_(S))和蒸腾速率(E)也呈现下降趋势,下降幅度为44.2%~75.0%、35.7%~69.5%、16.9%~53.3%;而胞间CO_(2)浓度(C_(i))则随着胁迫的加剧而显著升高,上升幅度为4.2%~20.0%。此外,PSⅡ最大光化学效率(F_(v)/F_(m))、PSⅡ电子传递量子产率(φ_(PSⅡ))、光化学淬灭系数(q_(p))和非光化学淬灭系数(q_(N))相较于对照组NF基本都呈现下降趋势,表现出显著的光抑制现象。结果揭示了高浓度臭氧对香樟幼苗光合特性的负面影响,为城市林木的保护和管理提供了重要参考。

To investigate the impact of tropospheric ozone(O_(3))on plant growth and its underlying mechanisms,and provide a scientific basis for the sustainable development of urban environments,using open-top chamber(OTC)exposure method,the effects of high concentrations of O_(3)on the photosynthetic characteristics of Cinnamomum camphora seedlings,a typical urban tree species in Changsha.The results indicated that O_(3)stress significantly inhibited the growth of C.camphora seedlings,leading to a decline in plant height and diameter at the base.Moreover,O_(3)treatment caused significant damage to the leaves.After two months of O_(3)stress,the content of chlorophyll a(Chl a),chlorophyll b(Chl b),and carotenoid(Car)in the leaves decreased 20.0%to 63.1%,8.2%to 34.7%,and 15.7%to 62.5%,respectively,compared to the control(NF),indicating a significant reduction in photosynthetic pigment content.Concurrently,the net photosynthetic rate(P_(n)),stomatal conductance(G_(S)),and transpiration rate(E)of the leaves also exhibited downward trends,with a decrease of 44.2%to 75.0%,35.7%to 69.5%,and 16.9%to 53.3%,respectively.However,the intercellular C02 concentration(C_(i))increased significantly with the intensification of stress,with an increase of 4.2%to 20.0%.Additionally,parameters such as the optimal photochemical efficiency of photosystem Ⅱ(F_(v)/F_(m)),the quantum yield of electron transport in photosystem Ⅱ(φ_(PSⅡ)),the photochemical quenching coefficient(q_(p)),and the non-photochemical quenching coefficient(q_(N))all generlly decreased compared to the control(NF),demonstrating significant photoinhibition.The findings revealed the adverse effects of high O_(3)concentrations on the photosynthetic characteristics of C.camphora seedlings,providing important insights for the protection and management of urban trees.