LARS Tech Report Number



This research was designed to study the relationship I between different densities of maize (Zea mays L.) canopies and the energy reflected by these canopies. Field plots were laid out, representing four growth stages of maize. Two plot locations were chosen, one on a dark soil and the other on a very light colored surface soil. Spectral and spatial data were obtained from color and color infrared photographs taken from a vertical distance of 10 m above the maize canopies. Estimates of ground cover were made from these photographs and were related to field measurements of leaf area index. Ground cover could be predicted from leaf area index measurements by a second order equation.

Color infrared photography proved helpful in determining the density of maize canopy on dark soils. Color photography was useful for determining canopy density on light colored soils, provided the percent ground cover did not exceed approximately 75%.

Microdensitometry and digitization of the three photographically separated dye layers of color infrared film showed that the near infrared dye layer is the most valuable (in canopy density determinations. Computer analysis of the digitized photography provided an accurate method of determining canopy density.

Date of this Version

January 1972