Oil, fatty acid, and protein content of seeds harvested from soybeans exposed to O₃ and/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 compositon 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 lioleic acid appeared to be depressed.