|Author||Cardenas, R. ♦ Gausman, H. W. ♦ Bowen, R. L.|
|Source||United States Department of Energy Office of Scientific and Technical Information|
|Subject Keyword||RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT. ♦ BORON ♦ TOXICITY ♦ CHLORINE COMPOUNDS ♦ CITRUS ♦ AERIAL SURVEYING ♦ LEAVES ♦ PATHOLOGICAL CHANGES ♦ EXPERIMENTAL DATA ♦ OPACITY ♦ REMOTE SENSING ♦ SPECTROPHOTOMETRY ♦ DATA ♦ ELEMENTS ♦ HALOGEN COMPOUNDS ♦ INFORMATION ♦ NUMERICAL DATA ♦ OPTICAL PROPERTIES ♦ PHYSICAL PROPERTIES ♦ PLANTS ♦ SEMIMETALS 560303* -- Chemicals Metabolism & Toxicology-- Plants-- (-1987)|
|Abstract||Film density measurements were used to discriminate between healthy Red Blush grapefruit trees and trees whose foliage exhibited boron (B) and chloride (Cl/sup -/) toxicity symptoms (affected). Citrus trees were photographed from an aircraft (3000 ft altitude) and a Truco's aerial lift (9 ft above trees) with a Hasselblad camera. Light reflectance of foliage of B/sup -/ and Cl/sup -/-affected trees produced pinkish (light red) images on EIR transparencies, compared with dark-red images for healthy trees. Citrus leaves affected by B and Cl/sup -/ toxicities were primarily characterized by scattered yellow spots on upper surfaces, brownish, resinous gummy spots on lower surfaces, and edge or tip burn. Affected leaves also had less chlorophyll, higher water content, and were thicker and smaller in surface area than healthy citrus leaves. Spectrophotometrically measured reflectance of top leaf surfaces revealed that B/sup -/ and Cl/sup -/-affected leaves, compared with healthy leaves, had decreased reflectance over the 750- to 1350-nm near-infrared wavelength range, and increased reflectance at the visible green peak of the 550-nm wavelength. Optical count densities were determined on transparencies using a Joyce, Loebl recording microdensitometer. For photographs at 3000 ft altitude, best discrimination between healthy and affected trees using optical density measurements was obtained with a blue bandpass filter; a red bandpass filter gave best discrimination for photographs taken at a height of 8 ft above the trees. 14 references, 2 figures, 3 tables.|
|Learning Resource Type||Article|
|Publisher Place||United States|
|Journal||Journal of the Rio Grande Valley Horticultural Society|
|Organization||Dept. of Agriculture, Weslaco, TX|
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