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Ozone and Sulfur Dioxide-Induced Changes in Soybean Growth. R. A. Reinert, Plant pathologist, Agricultural Research, Science and Education Administration, U. S. Department of Agriculture, Department of Plant Pathology, North Carolina State University, Raleigh 27650; D. E. Weber, plant pathologist, Office of Research and Development, Energy Effects Division, U. S. Environmental Protection Agency, Washington, DC 20460. Phytopathology 70:914-916. Accepted for publication 15 March 1980. Copyright The American Phytopathological Society. DOI: 10.1094/Phyto-70-914.

The growth of soybean was inhibited by exposure to 490 μg O₃/m³ (25 pphm) and 665 μg SO₂/m³ (25 pphm), singly and in combination, when plants were exposed for 4 hr three times per week for 11 wk. The main effects of O₃ were a reduction of shoot, root, and plant dry weight measured at 5, 7, 9, and 11 wk. The main effects of SO₂ were a reduction of shoot dry weight at 7 wk and total plant growth at 11 wk. Sulfur dioxide contributed to the reduced growth in soybean in the absence of visible SO₂ injury. The effect of SO₂ and O₃ in combination on soybean growth was only additive. Treatments containing O₃ reduced the numbers and dry weight of root nodules of soybean, compared with treatments without O₃.