Spectral- agronomic relationships of maize, soybean and wheat canopies.

The relationships of biophysical variables, including leaf area index, percent soil cover, chlorophyll and water content, to the visible and infrared reflectance of canopies are described. The effects on reflectance of cultural, environmental, and stress factors such as planting date, seeding rate, row spacing, cultivar, soil type and nitrogen fertilization are also described. The conclusions are that several key agronomic variables including leaf area index, development stage and degree of stress are strongly related to spectral reflectance and that it should be possible to estimate these descriptors of crop condition from satellite- acquired multispectral data. -from Authors