|Wall, Gerard - Gary|
|OTTMAN, MICHAEL - University Of Arizona|
|HUNT, L - University Of Guelph|
Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/2011
Publication Date: 12/20/2011
Citation: White, J.W., Kimball, B.A., Wall, G.W., Ottman, M.J., Hunt, L.A., 2011. Responses of Time of Anthesis and Maturity to Sowing Dates and Infrared Warming in Spring Wheat. Field Crops Research. 124:213-222.
Interpretive Summary: In order to provide reliable predictions of the potential impacts of global warming on agriculture, scientists require accurate information on how plants respond to temperatures. Greenhouse and growth chamber studies can precisely control temperature, but they often expose plants to lighting and humidity conditions that result in unrealistic plant responses. A system that uses infrared heaters to warm field experiments shows promise for warming while avoiding troublesome sources of bias. This paper describes research conducted in Maricopa, AZ that evaluates the utility of the so-called “temperature free-air controlled enhancement” (T-FACE) approach by comparing flowering and maturity times of wheat from plots sown at six dates using T-FACE and an additional nine dates that exposed the crops to an exceptionally wide range of temperatures (<32°F to > 105°F). The T-FACE treatments were intended to achieve a warming of +2.5°F during the daytime and +5.4°F at night; achieved warming was +2.3°F daytime and +5.0°F at night. T-FACE and sowing date treatments had large effects on phenology. Analysis using a computer simulation of wheat (the CSM-CROPSIM-CERES model) showed that the effects of T-FACE on wheat plants were similar to those expected from the equivalent natural changes in air temperature. However, the results also suggested that assumptions of the model about critical temperatures for wheat development should be revised, although it was cautioned that these results are from a single location and for a single wheat variety. Both the T-FACE and extreme sowing date treatments proved valuable for improving understanding of high temperature effects on plant processes. Use of both techniques should lead to improved information to guide predictions of how crops may respond to elevated temperatures, thus providing insights into how farmers might need to adapt to climate change.
Technical Abstract: Reliable prediction of the potential impacts of global warming on agriculture requires accurate data on crop responses to elevated temperatures. Controlled environments can precisely regulate temperature but may impose unrealistic radiation, photoperiod and humidity regimes. Infrared warming with automatic control of temperature rise has shown potential for warming field plots above ambient temperatures, while avoiding such biases. We assess the utility of a temperature free-air controlled enhancement (T-FACE) approach by comparing phenology of wheat from a series of six sowing date treatments using T-FACE and an additional nine sowing dates that exposed crops to an exceptionally wide range of air temperatures (< 0°C to > 40°C). The T-FACE treatments were intended to achieve a warming of +1.5°C during the daytime and +3.0°C at night; achieved warming was +1.3°C daytime and +2.8°C at night. T-FACE and sowing date treatments had large effects on phenology. A regression-based analysis of simulations with the CSM-CROPSIM-CERES model showed that effects of T-FACE on phenology were similar to what would be expected from equivalent changes in air temperature. However, systematic deviations from the expected 1-to-1 relation suggested that assumed cardinal temperatures for phenology should be revised. Based on the single cultivar and location, it appeared that the base temperature for emergence to anthesis should be reduced from 0° to -5°C, whereas the base temperature for grain filling should be increased from 0° to 4°C and the optimal temperature, from 30° to 34°C. Both T-FACE and extreme sowing date treatments proved valuable for improving understanding of high temperature effects on plant processes, as required for accurate prediction of crop responses to elevated temperatures under climate change.