Responses of growth, photosynthesis and related physiological characteristics in leaves of Acer ginnala Maxim. to increasing air temperature and/or elevated O3

Abstract Regional warming and atmospheric ozone (O 3 ) pollution are two of the most important environmental issues, and commonly coexist in many areas. Both factors have an intense impact on plants. However, little information is available on the combined and interactive effects of air warming and elevated O 3 concentrations on physiological characteristics of plants. To explore this issue, we studied variations in growth, photosynthesis and physiological characteristics of leaves of Acer ginnala seedlings exposed to control (ambient temperature and O 3 ), increasing air temperature (ambient temperature + 2 °C), elevated O 3 (ambient O 3 concentration + 40 ppb) and a combination of the two abiotic factors at different phenological stages by using open‐top chambers. The results showed that increasing air temperature had no significant effect on growth, but increased photosynthesis and antioxidant enzyme activity at the leaf unfolding and defoliation stages. In contrast, elevated O 3 decreased growth and photosynthesis and caused oxidative stress injury in A. ginnala leaves at each phenological stage. The combination of increasing air temperature and elevated O3 improved growth and net photosynthetic rates of tested plants and alleviated the oxidative stress compared to O 3 alone. Our findings demonstrated that moderate warming was beneficial to A. ginnala at leaf unfolding and defoliation stages, and alleviated the adverse effects of O 3 stress on growth, photosynthesis and the antioxidant system. These results will provide a theoretical reference and scientific basis for the adaptation and response of A. ginnala under regional air warming and atmospheric O 3 pollution.