Effects of simulated acid rain on the growth and antioxidant activity of Zebrina pendula

Zebrina pendula plants were sprayed with simulated acid rain at different pH values(6.7,5.6,4.5,3.5,2.5,1.5)in pot experiments,and the biomass,relative anthocyanin concentration,chlorophyll content,nitrate reductase activity,proline content,antioxidase activity(including superoxide dismutase,peroxidase and catalase),malondialdehyde content,and membrane permeability were determined.With decreased pH value from simulated acid rain,the dry weight,relative anthocyanin concentration,chlorophyll content,nitrate reductase activity and CAT activity decreased.SOD activity showed a trend of initial increase and then decrease.Proline content,POD activity,MDA content and membrane permeability increased with decreasing pH value.An integrated analysis indicated that under simulated acid rain-induced pH values 5.6-3.5,the growth and antioxidant activity of Z.pendula was only slightly inhibited and there was no effect on ornamental quality;under a simulated acid rain-induced pH value 2.5,the inhibition effect on growth and antioxidant activity became heavier and there was a slight effect on ornamental quality;under simulated acid rain-induced stress of pH value 1.5,the inhibition effect was large and there were visible injury symptoms on leaves,with a sharp decline in ornamental quality.