Wheat Grain Quality under Enhanced Tropospheric CO 2 and O 3 Concentrations

Abstract

It is expected that the progressive increase of tropospheric trace gases such as CO{sub 2} and O{sub 3} will have a significant impact on agricultural production. The single and combined effects of CO{sub 2} enrichment and tropospheric O{sub 3} on grain quality characteristics in soft red winter wheat (Triticum aestivum L.) were examined in field studies using 3 m in diam. open-top chambers. Wheat cultivars {open_quotes}Massey{close_quotes} (1991) and {open_quotes}Saluda{close_quotes} (1992) were exposed to two CO{sub 2} concentrations (350 vs. 500 {mu}mol CO{sub 2} mol{sup {minus}1}; 12 h d{sup {minus}1}) in combination with two O{sub 3} regimes (charcoal-filtered air vs. ambient air + 40 {plus_minus} 20 nmol O{sub 3} mol{sup {minus}1}, 7 h d{sup {minus}1}; Monday to Friday) from late March until maturity in June. Grain quality characteristics investigated included: test weight, milling and baking quality, flour yield, protein content, softness equivalent, alkaline water retention capacity, and cookie diameter. In general, exposure of plants to either elevated CO{sub 2} or weekly chronic O{sub 3} episodes caused only small changes in grain quality. Milling and baking quality score were not significantly changed in response to treatments in both years. Flour yield was increased by elevated CO{sub 2} but this increase was counteractedmore » when elevated CO{sub 2} was combined with chronic O{sub 3} exposure. Flour protein contents were increased by enhanced O{sub 3} under elevated CO{sub 2}. Although the single effect of either CO{sub 2} enrichment or chronic O{sub 3} exposure had some impact o grain quality characteristics, it was noted that the combined effect of these gases was minor. It is likely that the concomitant increase of CO{sub 2} and O{sub 3} in the troposphere will have no significant impact on wheat grain quality. 25 refs., 1 fig., 2 tabs.« less