| Taking 2-year old seedlings of Zelkova serrata, a Chinese second class key protected wild plant as test materials, this paper studied effects of 2.5 months simulated acid rain that included 4 different pH values (2.5, 3.5, 4.5 and 5.6, 5.6 as CK) on the gas exchange parameters, chlorophyll content and antioxidant enzyme activities of Z.serrata seedlings leaves. The results showed that with the decreasing of simulated acid rain pH value, the relative conductivities and malondialdehyde (MDA) content of leaves gradually increased, and there was a significant correlation between them. The net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) all showed a trend of increase first and then decrease, however, intercellular CO2 concentration (Ci) decreased continuously. The stomatal limitation value(Ls) showed an trend of gradual increase. Chl a and Chl b content decreased gradually, while the value of Chl a/Chl b showed no significant difference. The dismutase(SOD), catalase(CAT) and peroxidase(POD) activities were showed a single-peak curve which was firstly increased and then decreased, and the maximum of SOD appeared at pH 3.5, CAT and POD appeared at pH 4.5. The Pn value was the biggest, the antioxidant enzymes was high, and the injuries was small, when Z.serrata were stressed in simulated acid rain of pH 4.5. Therefore, Zelkova serrata can be considered as one of the landscaping species in East China. |
