Effects Of Simulated Acid Rain On Parameters Of Electrical Impedance Spectroscopy And Those Of Physiology In Euonymus Japonicus Stems And Leaves

Euonymus japonicus, belonging to the family of Celastraceae and the genus of Euonymus, is an evergreen broadleaf shrub used as strip hedge and column ball plant. It is the famous plant landscape materials with strong cold and drought resistance in northern China applied in urban road landscaping and used as important gardening materials. Acid rain has become an international environmental pollution, and acid rain stress on plant growth has serious adverse effects. Landscape plants improve the urban environment, and maintain ecological balance. Thus, the researches of simulated acid rain on the influence of physiological characteristic in Euonymus japonicus are important in application of urban greening. The objective of this study is to test the relationship between the electrical impedance spectroscopy (EIS) parameters and the physiological indexes, and to analyze the changes of chlorophyll fluorescence characteristic parameters under acid rain stress. The changes of EIS parameters, and the net photosynthetic rate, the intercellular CO2 concentration, transpiration rate, stomata conductance, chlorophyll fluorescence, and chlorophyll content were studied under simulated acid rain stress (pH 1.0, 2.0, 3.0, 4.0, 5.0).The main results are as follows:1. With increase of simulated acid rain concentration and long time stress, the changes of electrical impedance spectra and EIS parameters of Euonymus japonicus shoots and leaves occurred.2. There were significant positive correlations between extracellular resistance and chlorophyll contents, photosynthetic rate, stomatal conductance, as well as Fv/Fm of Euonymus japonicus leaves under pH1.0 of simulated acid rain stress (The coefficient of determination R2 was 0.91, 0.98, 0.97 and 0.91, respectively).3. There were significant positive correlations between extracellular resistance and chlorophyll contents, photosynthetic rate, stomatal conductance, apricot varieties as well as Fv/Fm of Euonymus japonicus leaves under simulated acid rain stresses (R2 was 0.95, 0.92, 0.98, 0.97 and 0.97, respectively).4. There were significant positive correlations bwteen intracellular resistance and Ci of Euonymus japonicus leaves under pH1.0 of simulated acid rain stress (R2 was 0.99).5. With increase of simulated acid rain concentration and long time stress, the chlorophyll fluorescence parameterΦPSⅡand Fv/Fm decreased.6. Effects of concentration of acid rain on stems showed promoting performance under the low concentration, and depressing performance under the high concentrations. When the acid rain was pH 1.0, the chlorophyll content was 76% lower than that of control, and for the concentration of pH 3.0, 4.0 and 5.0, the chlorophyll content was 84.2%, 88.5% and 92.6 % higher than that of control. Under pH value of 2.0 no significant difference was found.7. The results showed that the EIS parameters closely related to the physiological indexes, and they could indicate the degree of acid rain stress.