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Sulfur Dioxide Effects on Yield and Seed Quality in Field-Grown Soybeans. D. G. Sprugel, Assistant ecologist, Ecological Sciences Section, Radiological and Environmental Research Division, Argonne National Laboratory, Argonne, IL 60439, Present address: Department of Forestry, Michigan State University, East Lansing 48824; J. E. Miller(2), R. N. Muller(3), H. J. Smith(4), and P. B. Xerikos(5). (2)(3)(4)(5)Ecologist, assistant ecologist, scientific assistant, and scientific assistant, respectively, Ecological Sciences Section, Radiological and Environmental Research Division, Argonne National Laboratory, Argonne, IL 60439, (3)Present address: Department of Forestry, University of Kentucky, Lexington 40506. Phytopathology 70:1129-1133. Accepted for publication 7 March 1980. 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, 1980. DOI: 10.1094/Phyto-70-1129.

Field plots of soybeans were periodically exposed to elevated levels of sulfur dioxide (mean concentrations ranging from 0.09 to 0.79 ppm during fumigation) with an open-air fumigation system which minimized disruption of the normal crop environment. Although visible injury was observed in only two plots, yield at harvest was reduced in every fumigated plot compared to nearby unfumigated control plots. These yield decreases ranged from 5% to 48% and were somewhat greater than might have been expected from previous studies. Yield reductions seemed to be due to decreases in both the mean weight per seed and the number of seeds per plant. Harvest ratio (the ratio of bean weight to chaff weight at harvest) also was reduced in the more heavily fumigated plots. Seed quality was affected less than seed yield, although at the higher exposure levels protein content decreased slightly and concentrations of some mineral elements were altered.