Detection of water status in rice paddies using high resolution field spectra of visible to mid-infrared ranges

Visible to near- and mid-infrared spectral reflectance factors of rice plant canopies were measured to assess the possibility of radiometric detection of drainage and water deficit stress. The first derivative of spectra at a wavelength of 960 nm and the wetness index (ratio of mid- and near-infrared reflectances) were highly sensitive to the removal of paddy surface water even in a full canopy. The normalized difference index (NDVI) responded to water deficit stress about 2 to 3 weeks after drainage when the symptoms of wilting and leaf roll could be observed visually