Accession Number : AD0652679

Title :   PHYSICAL AND PHYSIOLOGICAL BASIS FOR DIFFERENCES IN REFLECTANCE OF HEALTHY AND DISEASED PLANTS,

Corporate Author : COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER N H

Personal Author(s) : Knipling,Edward B.

Report Date : 03 MAR 1967

Pagination or Media Count : 26

Abstract : Plant scientists are finding considerable use for false color aerial photography with Ektachrome Infrared Aero Film to distinguish vegetation types and to assess plant vigor. The basis for differences in the colored imagery of healthy and damaged plants on this infrared- and visible-sensitive film is their difference in reflectance in these spectral regions. Healthy leaves have a high infrared reflectance and a low visible reflectance, the latter due to a strong pigment absorption. The high infrared reflectance of leaves appears to be determined by their cellular and subcellular structure, but direct experimental evidence for the precise mechanism of internal reflectance is lacking. Any physiological disturbance to a leaf nearly always results in an increase in the visible reflectance, but the changes in infrared reflectance are variable. In addition to being dependent on the reflectance characteristics of individual leaves, the quantity and quality of energy reflected from vegetation surfaces is a function of the spectral distribution of incident solar radiation, the plant or crop geometry, and the relative amount of foliage and other reflecting surfaces. (Author)

Descriptors :   (*PLANTS(BOTANY), *INFRARED PHOTOGRAPHY), DISEASES, ORGANIC PIGMENTS, REFLECTION, AERIAL PHOTOGRAPHY, ABSORPTION SPECTRA, CHLOROPHYLLS, TREES, COLOR PHOTOGRAPHY

Subject Categories : Biology
      Cartography and Aerial Photography

Distribution Statement : APPROVED FOR PUBLIC RELEASE