Effects Of Tobacco Mosaic Disease On Tobacco Hyperspectral Characteristics

Tobacco diseases and insect pests occurrence assumes the trend of escalation in China, along with increasing demanding of enhancement of tobacco quality from international market and the tobacco industry, and the change of the crops layout and the change of the cultivation system. Hyper-spectral Remote Sensing Technology belongs to one kind of test technology with lossless, and can carry on the greater areas with the synchronized observation. To compare with the traditional monitor method, it was more economical, saving the time, saving physical resource and financial resource.The relationship of the spectrum characteristic of the tobacco mosaic disease to the severity of the tobacco mosaic disease was analyzed in qualitative and quantitative. The relationship of the spectrum characteristic of the tobacco mosaic disease to the pigment content of physiological index of the relevance strongest of the tobacco mosaic severity was analyzed in qualitative and quantitative. By Hyper-spectral Remote Sensing Technology, this experiment provided the theory basis for monitoring tobacco mosaic disease of greater areas.First, by analyzing the hyperspectral reflectance of tobacco leaves infected with TMV in the room, on the seventh day of the flue-tobacco leaves infected with TMV, it is founded that the spectral reflection at near-infrared waveband was drop ,while the surface of each group of leaf blade didn't obviously had the symptom. That was to say, on the seventh day of the flue-tobacco leaves infected with TMV, it could be diagnosed by hyperspectral technique for tobacco mosaic disease.Second, by observing the tobacco leaf blade of the infection tobacco mosaic virus of both the indoor and the outdoor, it was discovered that the spectral reflectance of leaf blade with disease was higher than that of the normal leaf blade at near-infrared waveband, while the spectral reflectance of leaf blade with disease was lower than that of the normal leaf blade in Visible Band.Third, the stepwise regression models of hyperspectral reflectance, first derivative spectra, spectral characteristic variables were established by analyzing the R2 and independent regression coefficients of 3 regression equations and the correlation between estimating values and measured values.The results showed that it was the best described with the first derivative spectra models,while it was described with spectral characteristic variables model with the worst effect, it was described with spectral reflectance model with the second effect.Fourth, by using ASD Field spec FR 2500, the leaves reflectance of flue-cured tobacco infected with tobacco mosaic viru(sTMV)were measured from the third day after artificial inoculation . Meanwhile, the pigment contents of flue-cured tobacco leaves were determined. Using linear and non-linear regression methods, the estimation models for pigment contents in disease tobacco were built based on a part of samples and confirmed through the test of the remainders. Results showed that contents of Chlorophyll a and Carotenoid in flue-cured tobacco leaves were predicted best with liner models based on SDb and Rg, respectively, whereas Chlorophyll b and Chlorophyll a+b with exponential models based on SDb. Relative errors of these models for estimating contents of chlorophyll a, chlorophyll b, chlorophyll a+b and carotenoid in the disease flue-cured tobacco leaves were -9.131%,-22.975%,-11.408% and -5.855%, respectively.Fifth, by analyzing the relationships of canopy spectral parameters to pigment contents, the models were established and tested, showing that it was feasible to estimate chlorophyll contents by spectral parameters. There were many differences between the coefficients and models of different positions,because chlorophyll contents in different positions had diversities, but the spectral parameters were changeless. However, the correlations between estimating values and measured values of each position leaf chlorophyll contents reached 0.05 significant level, so it suggested that estimating values were precise and people could selecte estimating model when needed.