Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2007
Publication Date: 6/15/2007
Citation: Burkey, K.O., Booker, F.L., Pursley, W.A., Heagle, A.S. 2007. Elevated carbon dioxide and ozone effects on peanut. II. Seed yield and quality. Crop Science. 47:1488-1497. Interpretive Summary: Current levels of the air pollutant, ozone, suppress agricultural production in most industrialized countries worldwide. Rising levels of carbon dioxide in the atmosphere, however, may protect plants from ozone damage, depending in part on the sensitivity of the crop. In this experiment, we evaluated the interaction of elevated carbon dioxide and ozone on seed yield and seed quality in peanut (Arachis hypogaea L.), an ozone-sensitive species, using open-top field chambers. Treatments were ambient, 1.5 and 2.0 times ambient carbon dioxide in combination with clean air, ambient ozone, and 1.5 times ambient ozone. Seed yield losses of up to 30% were observed at the highest ozone levels tested, and twice-ambient carbon dioxide levels ameliorated ozone suppression of yield. Gas treatment effects on peanut market grade characteristics were small. No treatment effects on the protein and oil contents of seeds were observed and only subtle shifts in lipid composition were found. Overall results suggest that increasing concentrations of tropospheric ozone will suppress yield of O3-sensitive peanut cultivars, while elevated carbon dioxide will moderate but not negate this response. Elevated ozone and carbon dioxide are not expected to have major effects on peanut seed composition and quality.
Technical Abstract: Tropospheric O3 is an air pollutant that is toxic to plants, causing changes in leaf biochemistry and physiology that lead to reductions in growth and yield. In many O3-sensitive crops, the adverse effects of O3 are ameliorated by elevated CO2, although the extent of protection by elevated CO2 varies with crop and cultivar, and gas concentration. A two-year open-top field chamber experiment was conducted to examine this interaction in peanut (Arachis hypogaea L., cultivar NC-V11) by testing the effects of O3 and CO2 mixtures on yield and seed quality. Treatments were ambient CO2 and CO2-enrichment of approximately 175 and 350 µmol mol-1 added 24 h d-1 in combination with charcoal-filtered (CF) air (23 nmol O3 mol-1), non-filtered (NF) air (48 nmol O3 mol-1), and NF air plus O3 (75 nmol O3 mol-1) applied 12 h d-1. Additional treatments were: a) high CO2-enrichment (630 µmol mol-1) in non-filtered air; and b) ambient air (chamber frames without plastic panels). Pod number, pod mass, and seed mass were suppressed 8 to 16% in NF air and 33 to 44% in elevated O3 relative to the CF air-ambient CO2 control. Elevated CO2 increased yield parameters 7 to 17% for plants grown in CF air and restored yield parameters in NF air and elevated O3 treatments to CF air-ambient CO2 control values. Gas treatment effects on peanut market grade characteristics were small with some evidence that peanuts matured earlier under elevated O3. No treatment effects were observed on the protein and oil contents of seeds. Effects of O3 and CO2 on peanut seed fatty acid composition included an increase in stearic acid (18:0) and a decrease in lignoceric acid (24:0) under elevated O3 and a shift from linoleic acid (18:2) to oleic acid (18:1) under elevated CO2. Yield parameters were similar between plants grown in non-filtered and ambient air (no chamber panels), suggesting that chamber effects on yield and seed quality were minimal. Subtle chamber effects on fatty acid composition were noted however, particularly a shift from linoleic acid (18:2) to oleic acid (18:1) in ambient air relative to NF air. Overall results suggest that increasing concentrations of tropospheric O3 will suppress pod and seed yield of O3-sensitive peanut cultivars, while elevated CO2 will moderate but not negate this response. Elevated O3 and CO2 are not expected to have major effects on peanut seed composition and quality.