Physio-biochemical Characteristics And The Response To Atmospheric Pollution Of Some Urban Greenizing Tree Species In Nanjing Area

In order to scientifically select and plant greenizing tree species and exert its function to purify,the biological characteristics and the response to atmospheric pollution of some urban greenizing tree species,which includeed Ginkgo biloba,Photinia serrulata,Zelkova schneideriana,Liquidambar formosana,Pistacia chinensis,and Magnolia grandiflora in Nanjing area were studied,besides these, biological changes of eight street tree species including Ginkgo biloba,Platanus hispanica,Zelkova schneideriana,Magnolia grandiflora,Osmanthus fragrans,Cedrus deodara,Ligustrum Lucidum andCinnamomum camphora etc,were also researched under natural pollution condition,Some conclusions are drawn as follows.1.With the difference of tree species and measured time,their photosynthesises displays the differently changing laws.Daily changes of Pn and Tr have two kinds of types,one-apexed curve and two-apexed curve,their apex shapes are different from tree species and seasons.But Daily changes of WUEs(water utilization efficiencies) of six tree species in different seasons show the similar changing laws,two-apexed curve.2.With the change of tree species and time,those factors affecting tree photosynthesis are also changing.Photosynthesis is synthetically influenced by many environmental factors,and there exist each other restricting relations among those factors,environmental factors acting as the leading function in different days are not uniform,the affecting intensities of the same environmental factors are also different from dates.3.The relations between daily changes of chlorophyll fluorescence parameters and environmental factors take on different changing laws.Daily changes of Fv/Fm,Yield,qP & Fv/Fo of 6 tree species all present M-shaped curves,that of qN takes on a W-shape curve,but daily changing curves of Fo,Fm and ETR are not completely uniform.The relationships between daily changes of chlorophyll fluorescence parameters and environmental factors are very close.In different seasons light intensity,temperature and humidity have different effects on both tree species and fluorescence parameters.4.With the exaltation of SO₂ concentration and the prolonging of stress time, different changes of physio- biochemical indices take place in tree leaves. Chlorophyll,carotenoid,and pH value of leaf sap present a decreasing trend,cell membrane permeability(MP)and malondehyde(MDA)come to go up,the contents of soluble sugar(SS),soluble protein(SP),proline,the activities of SOD & POD increasingly go up,or go up first,then decrease.With the exaltation of SO₂ concentration,Pn,Tr,stomal conductance(cond),inter-cellular CO₂ concentration(Ci) decrease markedly,and vapor pressure deficit(VPD)come to go up,but the changing ranges of WUE are different.With the exaltation of treated SO₂ concentration, Fv/Fm,Yield,qP,Fo,Fm,& Fv/Fo of 6 tree species show continuously decreasing trends,ETR goes up first,then decreases,qN value increases sharply,the SO₂ -tolerant abilities of six tree species by membership function way are assessed,the SO₂-tolerant order of assessment:Photinia serrulata＞Magnolia grandiflora＞liquidambar formosana＞Pistacia chinensis＞Z.schneideriana＞Ginkgo bilobaThere exist obvious differences among the physio-biochemical indices of street trees from different sampled sites of Nanjing.With the exaltation of pollutant concentration,from Najing Forestry University,Zhongshan mausoleum,Shanxi Road,Gulou,Xinzhuang to Taixin Road,chlorophyll,xanthorophylls,and leaf liquid pH value of eight tree species present an indentical changing law,namely a decreasing trend in May,July,september,and november.MP,MDA,Pro,POD,SOD and SP all present a ascending trend,but the ranges going up and decreasing are different from street tree species and seasons,the atmospheric pollution-resisting abilities of eight tree species from different sampled sites are assessed,the pollution-resisting order of assessment:Cinnamomum camphora＞Magnolia grandiflora＞Ligustrum Lucidum＞Osmanthus fragrans＞Platanus hispanica＞Cedrus deodara＞Z.schneideriana＞Ginkgo biloba...