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Effects of Increasing Doses of Sulfur Dioxide and Ambient Ozone on Tomatoes: Plant Growth, Leaf Injury, Elemental Composition, Fruit Yields, and Quality. H. E. Heggestad, Plant pathologist, Agriculture Research Service, U.S. Department of Agriculture, Beltsville, MD 20705; J. H. Bennett(2), E. H. Lee(3), and L. W. Douglass(4). (2)(3)(4)Plant physiologists, and statistical consultant, respectively, Agriculture Research Service, U.S. Department of Agriculture, Beltsville, MD 20705. Phytopathology 76:1338-1344. Accepted for publication 13 June 1986. 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, 1986. DOI: 10.1094/Phyto-76-1338.

Jet star, an indeterminant tomato cultivar, was exposed to 0.011, 0.059, 0.118, 0.235, and 0.468 ppm SO₂ in open-top field chambers supplied with nonfiltered (NF) air and to 0.005, 0.113, and 0.466 ppm SO₂ in chambers with charcoal-filtered (CF) air. Treatments were given 5 hr/day, 5 days/wk, for a total of 57 days during July, August, and September. Ripe fruit yields were decreased 16% by O₃ in NF compared with CF air. The highest dose of SO₂ given in CF air reduced fruit yield by 18%. Ambient O₃ and the SO₂ treatments were additive in their effects on fruit yields. Significant reductions in fruit numbers were observed. Fruit quality was not measurably altered. A negative linear response for ripe fruit yield vs. SO₂ exposure dose was demonstrated. As the SO₂ dose was increased, sulfur (S) content of the leaves increased linearly. In NF air, S content ranged from 1.62 to 2.56%. In both CF and NF air, S content of fruits was 0.24%; and, the SO₂ treatments did not cause measurable changes. Foliar concentrations of other elements were changed significantly by leaf position and harvest date, but not by SO₂ treatments.