performed using wavelength bands. Two different sets of bands were 
considered, Landsat MSS and Landsat thematic mapper. The thematic 
mapper is a second generation satellite multispectral scanner system 
planned for Landsat-D which is to be launched in 1981. The Landsat 
MSS bands are: 0.5-0.6 (green), 0.6-0.7, (red), 0.7-0.8 (near infrared), 
and 0.8-1.1 um (near infrared). The thematic mapper bands which are 
narrower and sample more parts of the spectrum are: 0.45-0.52 (blue), 
0.52-0.60 (green), 0.63-0.69 (red), 0.76-0.90 (near infrared), 1.55-1.75 
(middle infrared), and 2.08-2.35 um (middle infrared). The thematic 
mapper will also have a thermal infrared band, but thermal measurements 
were not acquired for this experiment. 
Results and Discussion 
One of the major long term goals of agricultural remote sensing 
research is to estimate or predict crop variables that can subsequently 
be used to assess crop vigor or be entered into a yield prediction model. 
To achieve this goal the complex relationship between the spectral re- 
flectance of crop canopies and their biological and physical character- 
istics must be understood. 
The effects of agronomic treatments on the spectra of spring wheat 
and the relation of canopy variables to multispectral reflectance were 
investigated. This information was used to develop equations for pre- 
dicting canopy variables from reflectance data. The analyses were 
performed using wavelength bands of the current and future satellite 
multispectral scanner systems. 
Effect of Agronomic Factors on Spectral Reflectance 
The crop canopy is a dynamic entity influenced by many cultural 
and environmental factors. The factors investigated in this experiment 
were available soil moisture, planting date, nitrogen fertilization, 
and cultivar. Several examples of spectra are shown in Figure l to 
illustrate the effect of the individual treatments on selected measure- 
ment dates. 
Each of the different treatment levels was compared to the Waldron 
(standard height) cultivar, early planting date, with nitrogen fertili- 
zation. The spectra were measured on June 18, 1976 during the stem 
extension phase of development, except for the comparison of cultivars 
which was on July 16, after heading. 
In 1976 the effect of available soil moisture on plant growth and 
spectral response was quite significant. Wheat planted on fallow land 
had more tillers and, therefore, greater biomass, leaf area, and per- 
cent soil cover than the wheat crop grown on land which had been cropped 
the previous year. These differences account for the decreased visible, 
increased near infrared, and decreased middle infrared reflectances for 
fallow treatment.