INFLUENCE OF DIFFERENT NITROGEN AND IRRIGATION TREATMENTS ON THE SPECTRAL REFLECTANCE OF BARLEY

Reflectance measurements was carried out in the field with a spectroradiometer covering the wavelength range 0. 4-2. 3 mu m. Twelve plots of barley were treated in six different ways: two irrigation and three fertilization levels. The spectral reflectances were determined through measurements performed in a nadir looking direction from a mobile platform 15 m above the ground. Reflectance factors of single spectral bands, reflectance factor ratios, and color coordinates were analyzed in relation to biomass, water content of the crop, and grain yield. The blue color coordinate Z was strongly related to the different irrigation levels, and relatively unsensitive to the amount of biomass. The Z coordinate was not well correlated to the IR/red ratio R(0. 80)/R(0. 68). The IR/ red ratio, on the other hand, was strongly coupled to the amount of biomass on each measurement date until approximately 20 July.