The Influence Of Nitrogen Levels To Populus Spectrum Characteristics And Photosynthetic Capacityon Different Soil Texture

107 populus(Populus×euramericana cv.“74/76”)which was fast-growing, superior, nosotropic had been the main fast-grown forest tree species in northern China.The 107 populus annual potted seedlings were used as experimental materials. The Spectral reflectance of leaf SPAD and nitrogen content from 107 populus were measured and calculated with Por Tab spectrometer produced by Analytical Spectral Device. Correlation between the Leaf spectral characteristics and the SPAD value and leaf nitrogen content were revealed. Estimate the SPAD value and leaf nitrogen content model was set up based on Vegetation index and which provide theoretical basis for detected plant growth and estimated amount of photosynthetic production by high spectral resolution remote sensing technology.The main results were as follows:(1) 107 populus high spectral reflection curve showed typical plant spectral characteristics. The first derivative spectra increased with increasing of N application within the scope of visible light 380~760nm which appeared the change trend of moving forward to long wave especially in 720-740 nm red edge area. The moving amplitude of loam situation was higher than that of sand which means N1 level could indicate 107 populus growth and development with loam situation.(2)The net photosynthetic rate, transpiration rate and stomatal conductance of each fertilization treatment on different N levels loam and sand were all rise with the increase of light intensity. The correlation among three indexes were positive. The Intercellular CO2 concentration were on the contrary and whose correlation with net photosynthetic rate was negative. Each treatment 107 populus leaf photosynthetic capacity on soil were all better than that on sand.(3) prediction models of 107 populus Leaf SPAD value and nitrogen content were established basing on hyperspectral information. The Quadratic polynomial in these prediction models had highest prediction and inversion accuracy.Reasonable Spectrum and photosynthetic technology could monitor 107 populus chlorophyll and nitrogen content after fertilization fast, nondestructive and accurate which could provided theoretical foundation for 107 populus high efficiency, high yield and ecological reasonable fertilization.