An empirical model of wheat baking quality under elevated CO2

Malcolm McCaskill1, Garry O’Leary2, Joe Panozzo2, Cassandra Walker2, Debra Partington1

1 Department of Economic Development, Jobs, Transport and Resources, Hamilton, Victoria, 3300, [email protected]

2 Department of Economic Development, Jobs, Transport and Resources, Horsham, Victoria, 3400

Abstract

Elevated CO2 (eCO2) is associated with lower grain protein concentration of wheat, and an inferior baking quality.  To extend the functionality of process-based models of wheat growth and nitrogen uptake, an empirical model for bread making quality (loaf volume and dough extensibility) was developed from five years of data from the free air carbon dioxide enrichment experiment at Horsham, Victoria, for three bread-wheat cultivars – Janz, Silverstar and Yitpi.

Loaf volume was modelled by a relationship derived by linear regression, which accounted for 82% of variation, and had  significant terms for eCO2, grain protein concentration, cultivar and a cultivar-CO2 interaction. A model of dough extensibility accounted for 79% of variation.. At a given protein concentration and CO2 level, Janz and Silverstar both had loaf volumes over 100 cm3 larger than Yitpi. It is suggested that acceptance criteria for grain receival into premium categories be based on cultivar-specific protein levels that produce equivalent loaf volumes. This would incentivise breeding efforts to improve the baking quality of wheat protein as an adaptation strategy for higher CO2 levels.