Estimating winter wheat plant water content using red edge width

Remote sensing of vegetation liquid water has important application in agriculture and forestry. The spectral index or features of water absorption in NIR and SWIR have been found useful for the detection of plant water content (PWC). It is unfortunately that the foliar liquid water absorption is superposed by the atmospheric vapor absorption, and it is very difficult to distinguish the contribution of foliar liquid water and atmospheric vapor on the water absorption spectral features. In this study, the novel methods using red edge width, which located outside of water absorption bands, were proposed for deriving winter wheat PWC from field canopy spectra. The significant positive correlation coefficients were observed between PWC and spectral reflectances in 740-900nm region for all the 6 growth stages. And this mechanism also affects the spectral red edge in 680-740nm. region. The correlation coefficients between PWC and red edge width derived from inverted gaussian model is significant at 0.999 confident level, and we established the statistical models for PWC by red edge width in all the 6 growth stages.