| In this paper, winter wheat of pots was planted as subject to establish a quantitative relationship between the spectral parameters and physiological parameters under low temperature stress. It was based on the feature spectrum parameters of winter wheat with low-temperature stress. The predicting models of winter wheat physiological cariables, based on spectral parameters, were constructed. The results showed that.1 The canopy spectral reflectance of winter wheat changed significantly with the different low-temperature stress. At early stage, the near-infrared band reflectance increased greatly with the stess strength of low-temperature increasingand the time extending. The reflection in visible band did not change significantly in the short term. the yellow and red bands began to trend levels, while the differences in near-infrared band decreased along withthe growth period developing. The first derivative of winter wheat canopy reflection had obvious spectral peaks in 500-550nm、700-750nm, and a trough in 550-600nm. Compared with the control group, the peak was weaken and the trough was flater with the different low-temperature stress, indicating the winter wheat of chlorophyll content reduced. In addition, the red edge presented the blue shift. While the red edge of T4 and T5 moved 1nm to the shorter wavelength, T6 moved 2nm.2 The chlorophyll content, carotenoid content, LAI, aboveground biomass and moisture content of winter wheat changed under different low-temperature stress. The chlorophyll content, carotenoid content and moisture content reduced.The damage of low-temperature stress became more severe while the stress strength of low-temperature increasingand the time extendin. The LAI and aboveground biomass increased gradually. But in the same period, with the stress strengthening of low-temperature and the extending of the time to prolong, thesedecreased even more pronounced.3 Five days after the stress to winter wheat, there were significant correlations between chlorophyll content and FDDVI (460,1095) FDDVI(463,1095) FDMSAVI(463,1095), carotenoid content and FDDVI (675,1096) FDMSAVI (675,1096), LAI and FDDVI (671,947)、FDRDVI (673,947), aboveground biomass and FDDVI (674,866) FDMSAVI (674,866), moisture content and FDRVI (677,968) FDNDVI (677,968). Ten days after the stress, there were significant correlations between chlorophyll content and FDRVI (678,883) FDRVI (735,883) FDNDVI (678,883), carotenoid content and FDDVI (730,992) FDRDVI (730,992) FDMSAVI (730,992), LAI and FDRVI (681,884) FDNDVI (681,884), aboveground biomass and FDDVI (781,673), moisture content and FDDVI (682,811) FDRVI (682,811) FDMSAVI (682,1119). Twenty days after low-temperature stress, there were significant correlations between chlorophyll content and FDRVI (667,1193) FDRVI (684,1193) FDNDVI (684,1193), carotenoid content and FDDVI (672,1174) FDMSAVI (672,1174), LAI and FDDVI (673,1009) FDRDVI (673,1009) FDMSAVI (673,1009), aboveground biomass and FDDVI (670,883), moisture content and FDDVI (747,1183) FDDVI (747,1031) FDMSAVI (747,1031) FDMSAVI (747,1183). These five agronomy parameters had significant relation with spectral parameters. According to the vegetation index model, the visible light vegetation index model moves to longer wavelength from five days to ten days stage after the stress to winter wheat. The visible light vegetation index model moves to longer wavelength from ten days to twenty days stage after low-temperature stress to winter wheat. The model based on the vegetation index showed the law. The law is also consistent with the changes of the physiological content after stress, which showed that the damage effect obviously in the early stage after the stressandthe damage of low-temperature weakened gradually as the growth period developing.4 The monitoring model of winter wheat was constructed with the agronomic parameters and spectral parameters. Meanwhile, the best arguments were FDDVI (460,1095) FDMSAVI (672,1174) FDDVI (671,947) FDDVI (674,866) FDDVI (747,1031). |
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