Submitted to: New Phytologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/4/2006
Publication Date: 3/22/2006
Citation: Morgan, P.B., Mies, T., Bollero, G., Nelson, R.L., Long, S.P. 2006. Season-long elevation of ozone concentration to projected 2050 levels under fully open-air conditions substantially decreases the growth and production of soybean.New Phytologist 170:333-343. Interpretive Summary: Ground-level ozone concentrations are increasing and based on the Intergovernmental Panel on Climate Change (IPCC), is predicted to be 20% greated in 45 years. Previously studies with chambers (both closed and open-topped) have shown losses in soybean biomass and yield due to ground-level ozone. Using a unique chamberless open-air fumigation system (Soybean Free Air gas Concentration Enrichment; SoyFACE) to increase ground-level ozone by about 20%, soybean aboveground plant material and seed yield losses were assessed under real-world field conditions. The total aboveground plant material production was decreased 17% by elevated ground-level ozone due to increased leaf mortality. Harvestable soybean yield losses were about 20%. These results validate previous studies and suggest that ground-level induced losses may be larger than previously predicted.
Technical Abstract: -Mean surface ozone concentration is predicted to increase 25% by 2050. Previous chamber studies of crops report large yield losses due to elevation of tropospheric ozone, and have been the basis for projecting economic loss. -This is the first study with a food crop (soybean) using Free-Air gas Concentration Enrichment (FACE) technology for ozone fumigation (www.soyface.uiuc.edu). A 23% increase in ozone concentration from an average daytime ambient 56 p.p.b. over two growing seasons decreased seed yield by 20%. -Total aboveground net primary production decreased by 17% without altering dry mass allocation among shoot organs, except seed. Fewer live leaves and decreased photosynthesis in late grain filling appear to drive the ozone-induced losses in production and yield. -These results validate previous chamber studies suggesting that soybean yields will decrease under increasing ozone exposure. In fact, these results suggest that when treated under open-air conditions yield losses may be even greater than the large losses already reported in earlier chamber studies. Yield losses with elevated ozone were greater in the second year following a severe hailstorm, suggesting that losses may due to ozone may be exacerbated by extreme climatic events.