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Etiology

Response of Pinto Bean to Simultaneous Exposure to Ozone and PAN. R. J. Kohut, Former Graduate Student, Department of Plant Pathology and Center for Air Environment Studies, The Pennsylvania State University, University Park, PA 16802, Present address of senior author: Ecology Consultants, Inc., 1716 Heath Parkway, Fort Collins, CO 80522; D. D. Davis, Associate Professor, Department of Plant Pathology and Center for Air Environment Studies, The Pennsylvania State University, University Park, PA 16802. Phytopathology 68:567-569. Accepted for publication 19 August 1977. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-567.

Ten-day-old pinto bean plants were exposed for 4 hr to either 588 μg/m³ (0.30 ppm) ozone, 247 μg/m³ (0.05 ppm) PAN, or the two pollutants combined at these concentrations. Ozone induced adaxial fleck whereas PAN produced mainly abaxial bronzing on the first trifoliolate leaf. Plant response to the combined pollutants was either additive or synergistic on the adaxial leaf surface and antagonistic on the abaxial leaf surface. The antagonistic abaxial response resulted in a nearly complete suppression of symptoms. The percentage injury for the combined leaf surfaces indicated an overall antagonistic response to the pollutants.