Growth of Radish and Marigold Following Repeated Exposure to Nitrogen Dioxide, Sulfur Dioxide, and Ozone. R. A. Reinert, Plant Pathologist, Agriculture Research Service, U.S. Department of Agriculture and North Carolina State University, Raleigh 27650. J. S. Sanders, Former Graduate Research Assistant, Department of Plant Pathology, North Carolina State University. Plant Dis. 66:122-124. Accepted for publication 13 April 1981. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1982. DOI: 10.1094/PD-66-122.

Radish and marigold plants were exposed to 0.3 ppm of nitrogen dioxide (NO₂), sulfur dioxide (SO₂, and/or ozone (O₃) nine times during a 3-wk period. No interactions among NO₂, SO₂, and O₃ were detected in measurement of radish foliage and root dry weight. Treatments containing O₃ reduced radish foliage and root (hypocotyl) dry weight 356 and 531 mg/plant, respectively. Interactions among NO₂, SO₂, and O₃ occurred in shoots and roots of marigold. SO₂ alone reduced marigold shoot and root dry weight, but this effect was reversed in the presence of O₃. The suppressive effect of SO₂ on root weight was also reversed by NO₂. Treatments containing SO₂ reduced dry flower weight 0.17 g/plant, but effects of the pollutant interactions observed in shoots and roots were not present.

Keyword(s): air pollutants, Rhaphanus sativus, Tagetes patula.