Relationship between sulfur dioxide concentration and yield of five crops in Australia

Mass emissions of SO₂, in Australia have tripled in little over a decade, to a level at which Australia is now a major source of global SO₂ emissions. To examine the relationship between SO₂ concentration and crop yield, five crops (wheat, soybean, peanut, navy bean and maize) were grown from the seedling stage to harvest in open top chambers under ambient climatic conditions. SO₂ was introduced into the chambers for 8h/day throughout this period at concentrations of about <13, 138 or 285 μg m^-3. The responses of the plants varied. Wheat and soybean were very sensitive, with yield reductions of about 5% and 25% at 135 and 275 μg m^-3, respectively. Navy beans and maize were less sensitive with a yield increase of about 10% at 140 μg m^-3, and unchanged yield at 285 μg m^-3. Peanuts were intermediate between these categories with yield reductions of about 5% and 10% at 140 and 280 μg m^-3, respectively.