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Plant response to variable ozone regimes of constant dosage

University of British Columbia

Most air pollutant investigations in controlled environments have utilized the conventional "steady state" exposure, yet air pollutant concentrations are rarely static in ambient conditions. Peak concentrations in air pollutant exposures vary in magnitude and occurrence despite equivalent doses and are likely to result in different degrees of injury to plants. The results of experiments involving 5 treatment regimes with a single peak concentration that varied in magnitude and occurrence while treatment doses remained equivalent, confirm this hypothesis and demonstrate that the levels of injury to bush beans (Phaseolus vulgaris)and radish (Raphanus sativus) may vary from 15 to 85% of the leaf area. An absolute injury assessment technique was developed for determining percent necrosis in the 5 treatments, with the same two crop species responding in a similar manner to the various constant dosage regimes. A simple workable model is presented that incorporates stomatal diffusive resistance along with the various exposure components, including cumulative dose, maximum concentration, and the interval of time during which the peak concentration was administered. Preliminary investigations failed to confirm an interaction between ozone and greenhouse whitefly in bush beans.

Text

2010-02-24

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http://hdl.handle.net/2429/20853

Plant Science

University of British Columbia

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