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The shifting influence of drought and heat stress for crops in Northeast Australia

Lobell, David B. and Hammer, Graeme L. and Chenu, Karine and Zheng, Bangyou and McLean, Greg and Chapman, Scott C. (2015) The shifting influence of drought and heat stress for crops in Northeast Australia. Global Change Biology . n/a-n/a.

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Article Link(s): http://dx.doi.org/10.1111/gcb.13022

Abstract

Characterization of drought environment types (ETs) has proven useful for breeding crops for drought-prone regions. Here we consider how changes in climate and atmospheric carbon dioxide (CO2) concentrations will affect drought ET frequencies in sorghum and wheat systems of Northeast Australia. We also modify APSIM (the Agricultural Production Systems Simulator) to incorporate extreme heat effects on grain number and weight, and then evaluate changes in the occurrence of heat-induced yield losses of more than 10, as well as the co-occurrence of drought and heat. More than six million simulations spanning representative locations, soil types, management systems, and 33 climate projections led to three key findings. First, the projected frequency of drought decreased slightly for most climate projections for both sorghum and wheat, but for different reasons. In sorghum, warming exacerbated drought stresses by raising the atmospheric vapor pressure deficit and reducing transpiration efficiency (TE), but an increase in TE due to elevated CO2 more than offset these effects. In wheat, warming reduced drought stress during spring by hastening development through winter and reducing exposure to terminal drought. Elevated CO2 increased TE but also raised radiation use efficiency and overall growth rates and water use, thereby offsetting much of the drought reduction from warming. Second, adding explicit effects of heat on grain number and grain size often switched projected yield impacts from positive to negative. Finally, although average yield losses associated with drought will remain generally higher than for heat stress for the next half century, the relative importance of heat is steadily growing. This trend, as well as the likely high degree of genetic variability in heat tolerance, suggests that more emphasis on heat tolerance is warranted in breeding programs. At the same time, work on drought tolerance should continue with an emphasis on drought that co-occurs with extreme heat. This article is protected by copyright. All rights reserved.

Item Type:Article
Business groups:Crop and Food Science
Subjects:Agriculture > Agriculture (General) > Agriculture and the environment
Agriculture > Agriculture (General) > Agricultural meteorology. Crops and climate
Agriculture > Agriculture (General) > Methods and systems of culture. Cropping systems
Deposited On:20 Sep 2015 23:31
Last Modified:20 Sep 2015 23:31

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