Elevated carbon dioxide changes grain protein concentration and composition and compromises baking quality. A FACE study J.F. Panozzo a, * , C.K. Walker a , D.L. Partington b , N.C. Neumann a , M. Tausz c , S. Seneweera d , G.J. Fitzgerald a a Department of Environment and Primary Industries, PB 260 Horsham, Victoria 3401, Australia b Department of Environment and Primary Industries, Napier Road, Hamilton, Victoria 3300, Australia c Department of Forest and Ecosystem Science, Melbourne School of Land and Environment, The University of Melbourne, Water Street, Creswick, Victoria 3363, Australia d Centre for Systems Biology, University of Southern Queensland, Toowoomba, Queensland 4350, Australia article info Article history: Received 11 April 2014 Received in revised form 21 August 2014 Accepted 22 August 2014 Available online 14 October 2014 Keywords: Free air carbon dioxide enrichment FACE Elevated carbon dioxide Wheat quality abstract Wheat is one of the major crops grown commercially and an important source of nutrition for humans. Changes in grain quality due to increasing levels of atmospheric CO 2 could have far-reaching impacts to human diets globally. Future wheat-growing conditions are expected to be impacted by climate change, particularly increases in carbon dioxide. Elevated CO 2 (eCO 2 ) has been shown to increase plant growth and yield, yet changes in grain properties also affect product quality. Using Australian Grains Free Air CO 2 Enrichment (AGFACE) technology we investigated the impacts of eCO 2 on grain quality over three seasons. Elevated CO 2 consistently decreased baking quality and grain protein percentage was consistently lower under eCO 2 , and protein composition changed towards a greater glutenin/gliadin ratio. Starch damage and amylograph peak viscosity were consistently reduced in the eCO 2 treatment in all years and for all cultivars. For other traits such as grain weight, milling quality, dough rheology, A-type starch granules and pasting viscosity the same altered effects were not consistent for cultivar or over years. The results suggest that grain and product quality of wheat grown under eCO 2 will be compromised in a high CO 2 atmosphere, and this may offset some of the potential yield benefits of eCO 2 . © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Atmospheric levels of carbon dioxide (CO 2 ) have significantly increased since pre-industrial levels (Hatfield et al., 2011) and current simulation models predict that the concentration of CO 2 will double in the next 50 years which will impact global weather patterns including ambient temperature, estimated to increase by an average of 0.5  C per decade. Throughout evolutionary history, plants have adapted to cope with changes in photosynthesis, however the rate of increase in CO 2 has never been as large before the industrial revolution. Due to the magnitude of climate change, resulting from increasing levels of CO 2 and the interaction with increasing ambient temperature, the need to understand the future effects on plant growth, grain yield and quality has become imperative. There have been numerous publications citing the effects of eCO 2 on plant growth, for example; Kimball et al., 1995; Taub et al., 2008. As CO 2 is the sole source of carbon for plants and is limiting under current atmospheric concentrations for C 3 plants, increasing levels of CO 2 are known to have a ‘fertiliser effect’ on growth of C 3 grasses including wheat (Ainsworth and Long, 2005). Typically, as the concentration of CO 2 increases, there is a concomitant increase in tissue carbon levels with a corresponding decrease in other el- ements including nitrogen and phosphorous (Loladze, 2002). The decrease in nitrogen concentration cannot be solely attributed to a dilution effect due to increased carbohydrate in the grain but due to a complex series of altered rates and pathways in the ribulose- biphosphate carboxylase/oxygenase (RuBisCO) pathway (Fangmeier et al., 1999). In cereal plants which contain relatively high concentrations of C and N, it has been shown that nitrogenous compounds such as grain protein, decrease and carbohydrates increase under eCO 2 conditions with consequences for biomass production, grain yield and grain quality (H€ ogy et al., 2009b; Kimball et al., 1995; Taub * Corresponding author. Tel.: þ61 3 5362 2129; fax: þ61 3 5362 2198. E-mail address: joe.panozzo@depi.vic.gov.au (J.F. Panozzo). Contents lists available at ScienceDirect Journal of Cereal Science journal homepage: www.elsevier.com/locate/jcs http://dx.doi.org/10.1016/j.jcs.2014.08.011 0733-5210/© 2014 Elsevier Ltd. All rights reserved. Journal of Cereal Science 60 (2014) 461e470