SATELLITE REMOTE-SENSING OF 3 WHEAT AND BEAN AGRONOMIC PARAMETERS

In this work a single TM4 band and two spectral indexes - ratio TM4/TM 3 and perpendicular vegetation index - were studied. Spectral digital counts obtained from TM/Landsat-5 tapes were corrected for radiometric and atmospheric effects. Wheat and bean agronomic parameters were gre en leaf area index, percent soil cover and chlorophyll density. These agronomic data were collected over commercial plantations on 1986 wint er. Discussion of results were carried out on physical and physiologic al bases. It is showed that there are good relationships between satel lite spectral parameters and agronomic parameters for both wheat and b ean. The possibility of estimating the vigor conditions of an agricult ural field from orbital data was stressed. Nevertheless, in some point of the growing season the agronomic parameters reach values so high t hat their relationships with spectral parameters become asymptotic rat her than linear, which would be the ideal situation. PVI, as expected, was powerful to minimize the effect of underlying tropical soils on c rops spectral responses.