Oil, Fatty Acid, and Protein Content of Seeds Harvested from Soybeans Exposed to O₃and/or SO₂

In a series of greenhouse experiments, we exposed soybean plants (`Corsoy-79') to low levels of O3 and SO2, singly and in combination. Exposure to O3 and SO2 alone increased the oil content of the harvested seeds, but the protein content was essentially unchanged. The seed oil: protein ratio increased with increasing pollutant concentration in both experiments. These responses, however, were not observed in seeds harvested from plants exposed to mixtures of O3 and SO2. Differences in fatty acid content and composition were also noted. Ozone alone caused an increase in seed fatty acid content as a result of increased linoleic and stearic acids coupled with decreased oleic acid. After exposure to SO2 alone, no significant alterations of the fatty acid composition were observed. No statistically significant pattern could be identified for the content of fatty acids in seeds harvested from plants exposed to the O3 + SO2 mixtures, although the accumulation of linoleic acid appeared to be depressed.