Canopy Spectral Characteristics And Growth Monitor Of Winter Wheat

Winter wheat is the main food crop in China.Real-time and rapid acquisition of winter wheat growth status is of great significance for ensuring food security in China.Hyperspectral technology can quickly and timely obtain crop growth information,and its accuracy can directly affect the accuracy and stability of the crop growth model.In order to accurately and timely understand the growth of winter wheat and improve the accuracy and stability of the estimation model,this study analyzed the SPAD value,leaf area index and aboveground dry biomass and canopy spectrum of winter wheat based on different tillage and fertilization test data.The variation law of winter wheat and the response characteristics of canopy spectra were studied,and the monitoring model of winter wheat growth was constructed.The main conclusions are as follows:(1)The SPAD value and leaf area index of winter wheat increased gradually from jointing stage to heading stage,and gradually decreased from heading stage to late filling stage.The above-ground dry biomass increased gradually with the growth period,and the growth from the jointing stage to the heading stage increased rapidly.The growth rate slowed down after the filling stage,indicating that the growth indicators of winter wheat in different growth stages were significantly different.(2)Spectral reflectance gradually decreases in the visible light band with the increase of SPAD value,LAI and biomass,and gradually increases in the near-infrared band,showing consistent regularity.The higher the SPAD value,LAI and biomass,the better the growth of winter wheat and the stronger the population growth.It indicates that the better the growth of winter wheat,the lower the spectral reflectance of the canopy in the visible light range,the stronger the absorption of visible light,the higher the reflectance in the near-infrared region,the stronger the reflection of near-infrared light,and the canopy spectrum can respond sensitively to crops.Growth.(3)The growth index model of the growth indicator established by the pretreatment spectrum is improved compared with the original spectral accuracy.The estimation model R2 of winter wheat SPAD value and aboveground dry biomass established by NC R2=0.61,0.91,RMSE= 3.15,5.84,precision.highest.The estimation index model of winter wheat leaf area index established by first derivative R2=0.61,RMSE =1.00,and the precision is the highest.