Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/1999
Publication Date: N/A
Citation: Interpretive Summary: Atmospheric concentrations of carbon dioxide (CO2) and ozone (O3) are increasing. Variations in CO2 concentrations have generally increased crop growth and yields. Chronic exposure to high ozone causes leaf injury and generally reduces crop growth and yields. Moderate drought reduces gas exchange and may reduce crop sensitivity to ozone. There is little information on the effects of air quality on grain quality. The main objective of this study was to evaluate the combined effects of soil moisture, CO2, and ozone on the quality of soft red winter wheat. Wheat was grown in large open top chambers with two soil moisture levels and four air quality treatments (ambient and elevated CO2 and/or ozone). Grain weights, milling quality, and flour yields were reduced in wheat exposed to ozone at current ambient CO2 levels. Elevated CO2 negated most of the harmful ozone effects. These results suggest that as atmospheric CO2 increases, the impact from occasional high ozone conditions on wheat grain quality will be minimal.
Technical Abstract: Enhanced levels of atmospheric carbon dioxide (CO2) or tropospheric ozone (O3) cause extensive changes in the physiology of crops. However, the effects of these combined gases on the grain quality of crops have not been characterized. From 1995 to 1997, field studies were conducted to investigate the interactive effects of soil moisture, CO2, and O3 on the grain quality of two soft red winter wheat (Triticum aestivum L.) cultivars (Gore and Susquehanna). Plants were grown in three meter diameter open-top chambers (OTCs) at USDA facilities in Beltsville, MD. The four air quality treatments were charcoal-filtered (CF) air, CF air with addition of approximately 150 uL CO2 L-1 (CF+CO2), non-filtered (NF) air with addition of 35 + or - 5 nL O3 L-1 (NF+O3), and NF air with addition of both CO2 and O3 (NF+CO2+O3). Test weights, milling quality scores, and flour yields were reduced in plants exposed to NF+O3, while flour protein content was increased in both cultivars under well-watered conditions, but only in Susquehanna under limited water availability. These results suggest that 500 uL CO2 L-1 would not be a level high enough to change winter wheat grain quality. However, actual and near-future tropospheric O3 levels are definitely sufficient to alter the grain quality of the winter wheat cultivars tested. The influence of soil moisture regime on the responses of these two cultivars to air quality, and more specifically NF+O3, indicates less responses under limited water availability.