Wheat Grain Quality under Enhanced Tropospheric CO2 and O3 Concentrations
1996
Rudorff, B. F. T. | Mulchi, C. L. | Fenny, P. | Lee E. H., | Rowland, R.
It is expected that the progressive increase of tropospheric trace gases such as CO₂ and O₃ will have a significant impact on agricultural production. The single and combined effects of CO₂ enrichment and tropospheric O₃ 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 ‘Massey’ (1991) and ‘Saluda’ (1992) were exposed to two CO₂ concentrations (350 vs. 500 µmol CO₂ mol⁻¹; 12 h d⁻¹) in combination with two O₃ regimes (charcoal-filtered air vs. ambient air + 40 ± 20 nmol O₃ mol⁻¹, 7 h d⁻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 CO₂ or weekly chronic O₃ 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 CO₂ but this increase was counteracted when elevated CO₂ was combined with chronic O₃ exposure. Flour protein contents were increased by enhanced O₃ exposure and reduced by elevated CO₂. Softness equivalent was increased by 2.4% by enhanced O₃ exposure but unaffected by O₃ under elevated CO₂. Although the single effect of either CO₂ enrichment or chronic O₃ exposure had some impact on grain quality characteristic, it was noted that the combined effect of these gases was minor. It is likely that the concomitant increase of CO₂ and O₃ in the troposphere will have no significant impact on wheat grain quality. Maryland Agric. Exp. Stn. Scientific Article 7836, Contribution no. 9164.
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