Injury and Yield Responses of Peanuts to Chronic Doses of Ozone in Open-Top Field Chambers

Abstract

Peanuts were exposed during 1979 and 1980 to concentrations of ozone (O3) that spanned those that occur in ambient air of peanut production areas in the USA. The different concentrations were obtained by adding O3 to the air of open-top field chambers for 7 h/day from the seedling stage to harvest. Ozone at seasonal 7-h per day concentrations (mean concentration for 7 h/day during the seasonal exposure period) equal to, or greater than, the ambient concentration caused foliar injury and decreased shoot and root weight for both years. Seasonal 7 h/day O3 concentrations in ambient air at our field site near Raleigh, North Carolina, were 0.052 and 0.056 ppm for 1979 (131 days) and 1980 (112 days), respectively. In 1979, marketable pod weight (yield) per plant at seasonal 7 h/day O3 concentrations of 0.049, 0.072, and 0.096 ppm was 0, 30, and 37% less, respectively, than for control plants in chambers that received charcoal-filtered air with a seasonal concentration of 0.026 ppm O3. In 1980, yield at seasonal O3 concentrations of 0.056, 0.076, 0.100, and 0.125 ppm was 14, 35, 52, and 72% less, respectively, than for the control treatment (0.025 ppm). Linear regression equations using data from 1979 and 1980 predicted yield losses of 17 and 21%, respectively, at a seasonal 7 h/day mean O3 concentration of 0.054 ppm.