Agriculture, Ecosystems and Environment 185 (2014) 24–33
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Agriculture, Ecosystems and Environment
jo ur nal home p age: www.elsevier.com/locate/agee
Elevated CO
2
alters grain quality of two bread wheat cultivars grown
under different environmental conditions
Nimesha Fernando
a
, Joe Panozzo
b
, Michael Tausz
c
, Robert M. Norton
d
,
Nathan Neumann
b
, Glenn J. Fitzgerald
b
, Saman Seneweera
a,∗
a
Department of Agriculture and Food Systems, Melbourne School of Land and Environment, The University of Melbourne, 4, Water Street, Creswick,
Melbourne, VIC 3363, Australia
b
Department of Environment and Primary Industries, Natimuk Road, Private Box 260, Horsham, VIC 3401, Australia
c
Department of Forest and Ecosystem Science, Melbourne School of Land and Environment, The University of Melbourne, 4, Water Street, Creswick,
Melbourne, VIC 3363, Australia
d
International Plant Nutrition Institute, 54 Florence Street, Horsham, VIC, 3400, Australia
a r t i c l e i n f o
Article history:
Received 6 August 2013
Received in revised form
17 November 2013
Accepted 19 November 2013
Keywords:
Elevated CO2
Grain protein
Grain minerals
Dough rheological properties
Bread quality
a b s t r a c t
Bread wheat (Triticum aestivum L. cv. Yitpi and cv. Janz) was grown under field conditions in the Aus-
tralian Grains Free-Air CO
2
Enrichment (AGFACE) facility. Ambient [CO
2
] (a[CO
2
], ∼384 mol mol
-1
) and
elevated [CO
2
] (e[CO
2
], ∼550 mol mol
-1
) were combined with two soil water levels (rain-fed and irri-
gated) and two times of sowing (TOS) in three consecutive years to provide six environments (2007-TOS
1
,
2007-TOS
2
, 2008-TOS
1
, 2008-TOS
2
, 2009-TOS
1
, 2009-TOS
2
). Grain samples were assessed for a range of
physical, nutritional and dough rheological properties. The effect of e[CO
2
] on thousand grain weight
(TGW) was significantly different in each growing environment: TGW was significantly increased under
e[CO
2
] only at 2007-TOS
2
(by 5%), 2009-TOS
1
(by 5%) and 2009-TOS
2
(by 15%) but not significantly
changed under other conditions. The magnitude of reduction of grain protein concentration at e[CO
2
]
differed among the growing environments but was highly correlated with the percentage yield stimu-
lation under e[CO
2
] (r
2
= 0.91) suggesting that grain protein concentration under e[CO
2
] was diluted by
increased yield. Across all treatments, grain nutrient concentration was significantly reduced by e[CO
2
]
for Fe (3.9%, 6.2%), Cu (2.2%, 3.4%), Zn (5.9%, 5.7%), Ca (5.6%, 7.3%), Mg (5.6%, 5.8%), Na (21.2%, 30.4%), S
(4.4%, 4.4%), P (4.1%, 3.2%) in cv. Yitpi and Janz, respectively. Effects of e[CO
2
] on grain Zn, Mg and Na con-
centrations were dependent on the growing environment. Relative reduction of grain S, Fe, Mg, Zn, P at
e[CO
2
] were significantly correlated with grain yield stimulation at e[CO
2
]. Reductions of these nutrients
under e[CO
2
] were not fully explained by biomass dilution as the relationships differed for each nutrient.
Under e[CO
2
], flour yield of cv. Janz was increased but that of cv. Yitpi was not changed. Even though
grain protein concentrations of both cultivars were similar at e[CO
2
], bread volume as inferred indirectly
by dough rheology parameters was 12% greater for cv. Janz (185 ± 5 cm
3
) than cv. Yitpi (162 ± 4 cm
3
) at
e[CO
2
]. This disparity may be related to the compositional changes in wheat flour protein at e[CO
2
], sug-
gesting that future breeding and adaptation strategies to improve the grain quality under e[CO
2
] should
consider the prevailing hydro-thermal conditions.
© 2013 Published by Elsevier B.V.
1. Introduction
Increasing carbon dioxide concentration ([CO
2
]) in the atmo-
sphere together with rising temperature and changes in rainfall
amount and patterns are current concerns for agricultural crop
production and crop quality in the near future (Miraglia et al.,
∗
Corresponding author. Tel.: +61 3 53214127/+61 4 0187 9853(mob.);
fax: +61 3 53214166.
E-mail addresses: samans@unimelb.edu.au, seneweera@gmail.com
(S. Seneweera).
2009). Under most emission scenarios atmospheric [CO
2
] (a[CO
2
])
is expected increase to ∼550 mol mol
-1
by 2050, causing global
temperatures to increase by an average of 1.5–4.5
◦
C with more fre-
quent occurrences of extreme climatic events such as heat waves
and/or drought (Carter et al., 2007). Several studies have shown that
wheat grain protein and mineral concentrations decrease under
elevated [CO
2
] (e[CO
2
]) (Kimball et al., 2001; Taub et al., 2008;
Högy et al., 2009; Fernando et al., 2012b). As wheat is a staple
food crop for almost half the world’s human population, and one
of the main sources of minerals and protein in most developing
countries (Cakmak, 2004), this is of concern for food security and
human health. Grain protein concentration is also an important
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http://dx.doi.org/10.1016/j.agee.2013.11.023