537 
the radiance surface temperature monitored with a thermal infrared radiometer, assuming that the 
infrared emissivity of vegetation is relatively constant and close to 1, and that the effects of the 
atmosphere can be disregarded. 
Crop Stems Stems 
Figure 2 - The normalized temperature Tn (f = 37 GHz, 0 = 
45*) of a wheat canopy: 1. Full crop, 2. without ears, 3. 
without leaves, 4. only stems, 5. bare soil. (V = and H = 
vertical and horizontal polarizations) 
Fig. 2 shows a sequence of measurements on well developed wheat, observed as full crop (1) with 
a PWC = 1 Kg/m 2 and after cutting different plant constituents, i.e.: stems with leaves and 
without ears (PWC = 0.8 Kg/m 2 ) (2), stems with ears and without leaves (PWC = 0.85 Kg/m 2 ) (3), 
stems only (PWC = 0.65 Kg/m 2 ) (4), and soil after the cutting of plants (gravimetric soil moisture 
= 12%) with a small residue of vegetation biomass (5). 
Figure 3 - The brightness temperature at V and H pol. (f - 37 
GHz, 0 = 45*) of a layer of wheat ears (PWC = 0.28 Kg/m ) as 
a function of azimuth angle *