Research On Photosynthetic And Spectral Characteristics Of Landscape Plants Exposed To Nitrogen Dioxide Pollution

Pollution of nitrogen dioxide in air is increasingly more seriousm, and nitrogen dioxide is becoming one of the main contaminants in air, which causes big damages to people’ health and environment, so it wil be a significance to find the Ecological remediation plants in polluted areas by nitrogen dioxide. The article takes common garden species in heavy pollution area of Wugang jiaohua district（abbreviation Wugang）, Contaminated zone of Qingshan’ Heping garden （abbreviation Qingshan）, and the control area of Huazhong Agricultural University （abbreviation Huanong） as the objects of research, and measure the photosynthetic performance, chlorophyll concentration and nitrogen content in the selected plants leaves by portable photosynthesis （Li-6400）, portable spectrometer（ASD FieldSpec HandHeld）, spectral reflectance SPAD-502and kieltec2300automatic azotometer. Some Ecological remediation plants in polluted areas are selected through analysing the resistance and absorbing ability of plant to NO2; researching, modeling and inspecting on the relationship between spectroscopic data and nitrogen content on selected plant are conducted through studing the spectrum and nitrogen content of of leaves, which also supplies reference to examine air pollution. The main results are as follows:1. The atmospheric NO2concentration were detected in different pollution areas, The control of atmospheric NO2concentration in region Huanong was low, which is only47.177（μg/m3）, While the heavy pollution area of Wu gang atmospheric NO2concentration is3.07times of the control region, The atmospheric NO2concentration of general pollution area Qingshan is only1.18times of the control.2. Plants’net photosynthetic rate, transpiration rate, stomatal conductance, Water Use Efficiency and CO2thickness intercellular in three function areas:Central China Agriculture University campus>Heping garden>Wugang Jiaohua, and stomatal conductance decline range is very large, Water Use Efficiency decline is small, besides the vapor pressure deficit on leaves in upward trend, and rise range is very large. It explains in NO2pollution environment, external environment have effect on photosynthesis mainly through limit Stomatal conductance, plants need continuous Inducing changes in the external environment to adapt adjusting stomatal opening degree, in order to maintain the balance of water desorption and photosynthesis. 3. Through light response indicator analysis on same species in different pollution areas, we find the plants in NO2serious polluted area have decreased capacity in taking advantage of light compared with control group, while LCP increased in different degree, max net photosynthetic rate and apparent quantum efficiency have decreased in different degree, LSP fluctuate irregularly. Moreover, anti-polluting stronger, the plants’ light response indicator smaller in pollution; conversely, the change bigger.4. Through comprehensive evaluation on7resistance index, we conclude19species’ anti-NO2pollution according to the sequence; The strong anti-pollution; Ligustrum lucidum, Koelreuteria paniculata, Viburnum odoratissimum, Cinnamomum camphora, Magnolia; the medium anti-pollution:Osmanthus fragrans, Pittosporum tobira, Platanus orientalis, Photinia serndata, Prunus ceraifera, Pittosporum tobira, Rhododendron simsii, Eriobotrya japonica, Elaeocarpus sylvestris; the weak anti-pollution:Lagerstroemia indica, Nerium oleander, Mahonia beaill, Ginkgo biloba and Reineckia triandra.5. Through the comparison and correlation analysis, we come to the conclusion that strong absorption of NO2pollution gases and medium nitrogen content in plant leaf have no significant correlation to the nitrogen content in soil,which can explain nitrogen content in plant leaf mainly comes from the absorption of NO2in air rather soil. These species mainly include:Morus alba, Nerium oleander, Bambusoideae, Paulownia spp., Cottonrose Hibiscus, Jasminum mesnyi, Magnolia grandiflora, Lagerstroemia indica, Reineckia triandra, Pittosporum tobira, Photinia serndata, Broussonetia papyrifera etc.; Suction dirt poor tree species:Ginkgo biloba, Platanus orientalis, Ligustrum lucidum, Osmanthus fragrans, Pittosporum tobira, Rhododendron, Prunus ceraifera, Cinnamomum camphor a, Viburnum odoratissimum var.awabuki, Elaeocarpus sylvestris, Eriobotrya japonica etc..6. According to the different resistance and absorption ability of garden plants to NO2, suitable pants in NO2-polluted area are list as follows:Suitable plants:Magnolia grandiflora, Morus alba L, Bambusoideae, Cottonrose Hibiscus, Broussonetia papyrifera;Relatively Suitable plants:Ligustrum lucidum, Platanus orientalis, Osmanthus fragrans, Photinia serndata, Pittosporum tobira, Cinnamomum camphora, Viburnum odoratissimum var.awabuki, Nerium oleander, Paulownia spp., Jasminum mesnyi, Lagerstroemia indica, Reineckia triandra, Pittosporum tobira; Not suitable pants:Ginkgo biloba, Rhododendron, Prunus ceraifera, Elaeocarpus sylvestris, Eriobotrya japonica, Mahonia beail.7. The Garden plants studied have different nitrogen content, the overall spectral curve substantially are similar. The biggest difference is reflected in the spectral reflectance of the green peak, Red Valley, and near-infrared sensitive bands, other bands was not significantly different. The First and second-order differential spectral curve of spectral reflectance can present the changed characteristics of leaves with different nitrogen content, which is,different in the sensitive bands, while other bands was not significantly different. These sensitive bands are an important indicator of the establishment of the the spectral inverse model of the plant leaf nitrogen content.8. Nitrogen content in correlation with the original spectrum and the reciprocal spectrum is significantly lower than with the first and second order differential spectra, especially the second-order derivative spectra. The correlation curve between the first order differential and plant nitrogen content exhibits regular decline and rising in the range of400～700nm band. The rest of the band is more volatile, but the correlation is higher.9. Single spectral parameters have better correlation with the nitrogen content of plant leaves, especially the wavelength corresponding to the first order differential value of Green peak, Red Valley, and Yellow edge; But the maximum occurs in the composite parameters; The correlation of parameters combined by red-edge, blue-edge and yellow-edge parameters is good as well.10. Parametric SR750₇10and the model of leaf nitrogen content:y=0.8312x2-7.1923x+30.736, R2=0.4569are finally determined as the independent variables Inversion by filtering, modeling and the accuracy test.