| Green plants have strong absorption in the red band,highly reflective of the near infrared band,normalized difference operation of these two bands can be obtained normalized difference vegetation index(NDVI),reflect the changes on the plant growth and physiological activity of the normalized difference vegetation index has a strong sensitivity,growth status and soil moisture the use of NDVI monitoring of winter wheat,to guide agricultural production,is of great significance to the development of modern management technology of winter wheat field.The study of Winter Wheat in Dryland water-saving experiment Northwest Agriculture and Forestry University Key Laboratory of agricultural irrigation experimental station,irrigation amount of 60 L/m2(W1),50 L/m2(W2)and 30 L/m2(W3),0 L/m2(W4)4level.Irrigation was carried out at overwintering,jointing and filling stage respectively.The sowing rate was used to control the density,the high density(D1)sowing amount of150kg//hm2,and the low density sowing(D2)75kg/hm2.NDVI,field meteorological data and soil moisture data were collected in winter wheat,overwintering stage,jointing stage,filling stage and mature stage respectively.Analysis of NDVI diurnal variation pattern of winter wheat and its correlation with meteorological factors and soil moisture,and the use of multiple regression and stepwise regression model of two kinds of methods,and provide theoretical and technical support for field information monitoring of winter wheat.In this paper,the variation law of winter wheat NDVI days,the relationship between NDVI and meteorological factors,and the correlation between NDVI and soil moisture were analyzed.(1)the diurnal variation of NDVI in winter wheat under different growth stages was studied.The correlation between NDVI and single time series showed two linear parabolic well,in winter wheat,determination coefficient of fitting results of NDVI were 0.9,0.934,the coefficient of determination at jointing stage was 0.954,0.887,0.829 for the coefficient of determination in filling stage.However,the overall variation of NDVI in winter wheat was not large,and the fluctuation of NDVI during grain filling period was larger,because of the abnormal weather changes during the growth period,which led to the fluctuation of NDVI in winter wheat.The measured data show that the model has good accuracy.The two foldinversion model of NDVI and time series for winter wheat at different growth stages can provide theoretical support for the rapid acquisition of winter wheat NDVI.(2)through the analysis of the relation between growth period NDVI and meteorological factors,including winter NDVI and air temperature and relative humidity of the highest correlation,jointing NDVI and air temperature and ground temperature of the highest correlation,filling stage,ground temperature and relative humidity and correlation of winter wheat NDVI best.For the meteorological factors such as ground temperature,air temperature and relative humidity,there is a certain correlation between NDVI in winter wheat and that in winter wheat.The correlation between different meteorological factors and winter wheat is different from that of NDVI.The correlation model can correct the NDVI of Winter Wheat under abnormal weather conditions.(3)were used in different growth stages of winter wheat and soil moisture NDVI multivariate regression and stepwise regression simulation results show that the soil moisture in different growth stages of winter wheat NDVI with different depth is associated by the difference after treatment in winter,NDVI value and 20 cm and 60 cm depth of soil water water difference correlation.At jointing stage,NDVI difference was better than soil moisture difference at surface 10 cm and 60 cm depth.The correlation between NDVI and soil moisture at grain filling stage was similar to that at jointing stage,and the difference of soil water content between 10 cm depth and 60 cm depth was also better than that of NDVI.The winter wheat of three different growth stages showed the difference of soil moisture between the surface 10 cm and the depth of 60 cm,and had a good correlation with the NDVI difference.Therefore,NDVI is only suitable for inversion of soil water content under these two depths.The conclusions provide a reference for NDVI inversion of Winter Wheat Soil moisture. |
PDF Full Text Request