Abstract: In order to find the sensitive parameters for remote sensing identification among barley,spring wheat and naked oats,these three crops were planted in the test fields of Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences.The spectral reflectances and chlorophyll contents of the three crops were measured by hand-held ASD spectrometer and chlorophyll analyzer SPAD502.The first order differential of the three kinds of crops canopy spectral reflectance was obtained by differential calculation.Nineteen spectral characteristic variables and SPAD values,such as spectral position variables,spectral area variables and vegetation index variables,were selected for statistical analysis,and the following conclusions were obtained.There were differences in the characteristics of twenty remote sensing parameters among the three crops.First,in the ten position variables of the three crops,the wavelength position corresponding to the red edgeλr was very different.Spring wheat was characterized by a lower Dy than the other crops in the first order differential spectrum in the yellow edge.Meanwhile,naked oats was characterized by a lower maximum Db than the other crops in the first order differential spectrum in the blue edge,and barley was characterized by a higher maximum Dr than the other two crops in the first order differential spectrum within the red edge.Second,in the three area variables,the SDr of barley and the two parameters of SDb were larger than those of spring wheat and naked oats;and the value of SDy was lower than that of spring wheat and naked oats.At the same time,the SDr of spring wheat and the two parameters of SDb were smaller than those of barley and naked oats,while the value of SDy was larger than those of barley and naked oats.Third,among the six vegetation index variables,the characteristics of the two parameters SDr/SDb and SDr/SDy were obviously different,while the differences of the other four parameters were not apparent.The SDr/SDy value of spring wheat was lower than those of the other two crops;while the SDr/SDb value of barley was lower than those of the other two crops.The naked oats SDr/SDb value was higher and similar to the barley value,but the SDr/SDy value was lower than the barley value,but higher than the spring wheat value.Fourth,leaf SPAD values of naked oats were greater than sixty and higher than those of the other crops;while the value of barley was lowest and the value of spring wheat was in the middle.There were significant differences in the spectral reflection characteristics and chlorophyll content values of the three kinds of crops in the heading stage,which will provide a new opportunity for remote sensing to distinguish these three kinds of crops.

Key words: Barley;Spring wheat;Naked oats;Chlorophyll content;Spectral reflectance;Feature analysis