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Author Miller, P. R. ♦ Quick, T. C. ♦ Vincent, P. L. ♦ Thomas, M. A.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT. ♦ ENVIRONMENTAL SCIENCES ♦ DOSE-RESPONSE RELATIONSHIPS ♦ MATHEMATICAL MODELS ♦ LEAVES ♦ CHLOROSIS ♦ PHOTOCHEMICAL OXIDANTS ♦ ECOLOGICAL CONCENTRATION ♦ TOXICITY ♦ CHRONIC EXPOSURE ♦ DAILY VARIATIONS ♦ EQUATIONS ♦ HOURLY VARIATIONS ♦ PINES ♦ SAN BERNARDINO MOUNTAINS ♦ SEASONAL VARIATIONS ♦ SYMPTOMS ♦ TRANSPIRATION ♦ CONIFERS ♦ MOUNTAINS ♦ PATHOLOGICAL CHANGES ♦ PLANTS ♦ TREES ♦ VARIATIONS 560300* -- Chemicals Metabolism & Toxicology ♦ Environment, AtmosphericChemicals Monitoring & Transport(-1989)
Abstract Observations were made biweekly of the same needles of ponderosa and Jeffrey pines having different amounts of chronic injury and located in plots along a gradient of decreasing oxidant dose in the San Bernardino mountains. Changes in the rate of foliage injury development were based on the percent of the total needle length with chlorotic mottle, intensity differences in that symptom and needle abscission. Hourly temperatures and relative humidities and biweekly predawn xylem water potential and minimum daily stomatal resistance were inputs to a model that calculated daily potential (T/sub p/) and actual (T/sub a/) transpiration. Cumulative dose was calculated from hourly oxidant measurements. A positive relationship was noted between increasing (T/sub p/) and oxidant dose on a daily basis, suggesting a dose response model including transpiration rate and seasonal pattern as an important modifier of injury development. The ratio T/sub a//T/sub p/, an index of the seasonal moisture regime used to modify dose, did not show any influence on injury over the narrow range experienced in 1976. Linear equations describing within-season injury showed differences that were related to the pre-existing amount of chronic injury, i.e., number of annual needle whorls retained. Symptom intensity decreased overwinter.
Educational Use Research
Learning Resource Type Article
Publisher Date 1978-09-01
Publisher Place United States
Journal Phytopath. News
Volume Number 2
Issue Number 9
Organization Pacific Southwest Forest and Range Experiment Station, Riverside, CA (USA)


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