Physiological And Ecological Parameters Inversion Of Spring Wheat In Semi-arid Region Based On PROSAIL Model

In semi-arid area,drought is the main cause of crop failure.Thus,It’s necessary to monitor the drought degree,which is the founder of reasonable irrigation.On the other hand,the spring wheat is the main grain crop in semi-arid area.Using remote sensing technology to monitor drought cannot harm the crop and can quickly acquire the crop drought degrees in expensive area,which is abide to the criterion of modern agriculture.In the study,taking spring wheat in semi-arid region of the Loess Plateau as research objects.The spectral reflectance of the spring wheat were measured by ASD.At the same time,the physiology and ecological parameters were also measured.Then,the feasibility of monitoring the drought of spring wheat based on the retrieved parameters of PROSAIL model was probed by analyzing the response of model simulated spectral reflectance to input parameters,the relationships between input parameters of model and drought degrees and spectrum simulation accuracy under different drought stress.Later,we revised the model’s export according to the relationships measured reflectance and model simulated reflectance.Consequently,we build the comparison table of physiology and ecological parameters and canopy reflectance.Finally,we stimulated the parameters in spring wheat plating region based on Landsat 8 image.The main results may list as follows:(1)The correlation ships between chlorophyll a and b content(Cab),equivalent water thickness(EWT),leave area index(LAI)and crop drought degree were significant.There was no dependency between leaf mass per area(LMA)and crop drought degree.And each input parameter of PROSAIL model had a different response range to canopy spectra reflectance of spring wheat.It’s reasonable to using PROSAIL model estimated Cab,EWT and LAI.(2)We used the empirical model to modify the modeled reflectance and the error of revised reflectance was about 15%.(3)The Landsat image’s estimated results were reliable,which can distinguish the drought of crop and guide the irrigation.(4)The estimated results showed that measured parameters were correlated with estimated parameters.The R2 of Cab,EWT and LAI were 0.75,0.70 and 0.73,respectively.