Abstract: By field experiments, the hyperspectral reflectance of winter wheat canopy with different moisture and nitrogen conditions during growth periods of 2010 and 2011 was measured by portable field spectrometer ASD. The canopy spectral characteristic in the presence of different leaf area index(LAI) , different chlorophyll content(SPAD value) and different water and nitrogen stress was analyzed. Results showed that peak of reflectance (green) and valley of adsorption (red) became more obvious with the increase of LAI and SPAD. The hyperspectral reflectance of winter wheat canopy was different in the presence of different water and nitrogen stresses. In the visible light band, the reflectivity increased with the decrease of nitrogen, but reduced in the near-infrared band.The research result could be a scientific support for winter wheat growth detection and water-saving irrigation.

Key words: winter wheat, spectral characteristic, water and nitrogen stress, leaf area index, chlorophyll content