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© Copyright 2009 AACC International.
Published January 2009.
Implications of global climate change for wheat-grain quality
S. Uthayakumaran, I. Batey, C. Wrigley. Food Science Australia, Sydney, Australia
Uthayakumaran, S., Batey, I., Wrigley, C. 2009. Implications of global climate change for wheat-grain quality. Online. AACC International Cereal Science Knowledge Database
Increasing levels of carbon dioxide in the atmosphere are predicted to cause warmer temperatures (especially the daily minima), changed patterns of rainfall, and increased frequency and severity of heat-stress episodes, together with decreased frost frequency and rising sea levels. These trends imply a future of fluctuations in wheat yield and quality. Increased carbon dioxide is known to act as a “carbon fertilizer”, raising biomass and grain yields, but lowering grain-protein levels. Higher growing temperatures may mean greater dough strength for cooler wheat-growing regions, but wheat is already produced in regions where growth temperatures are well above the ideal (15°C). Climate-change models indicate that heat-stress episodes (a few days with maxima over 35°C) will be more frequent during the grain-filling period, resulting in harvested grain with dough strength weaker than expected for the combination of variety and protein content. However, certain varieties show some tolerance to the dough-weakening effects of heat stress. Gluten proteins from heat-stressed tolerant varieties have a higher molecular-weight-distribution than proteins from susceptible wheats. This finding is consistent with our present knowledge of the relationships between protein composition and dough strength. However, it does little to clarify what heat stress has (or has not) done to cause these differences in protein composition. Genetic study of tolerant versus susceptible varieties should shed light on the molecular reasons for these differences, thereby providing a basis for creating heat-tolerant genotypes.
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