Wheat responses to a wide range of temperatures: The hot serial cereal experiment

Concomitant with the increase in Earth's atmospheric CO₂ concentration, temperatures are warming on a global scale. Crop growth models are useful tools to predict the likely effects of these global changes on agricultural productivity and to develop strategies to maximize the benefits and minimize the detriments of such changes. However, few models have been tested at the higher temperatures expected in the future. Therefore, we conducted an experiment, termed the Hot Serial Cereal Experiment, on wheat (Triticum aestivum L.)-the world's foremost food and feed crop-to obtain a dataset appropriate for testing the high-temperature performance of wheat growth models. Wheat was planted serially about every 6 wk for over 2 yr at Maricopa, AZ, USA, which experiences the whole range of temperatures at which plants grow on Earth. In addition, on six planting dates, infrared heaters in a temperature free-air controlled enhancement (T-FACE) system were deployed over one-third of the plots to warm the plots by an additional 1.5°C during daytime and 3.0°C at night. Overall, a dataset covering 27 differently treated wheat crops was obtained covering an air temperature range from -2 to +42°C. Crop grain yields ranged from 0 to 800 g m^-2. Crops planted in midwinter (normal planting time) yielded the most, as expected. Crops planted in fall suffered frost damage that was ameliorated by T-FACE warming, whereas spring-planted crops had lower yields that were exacerbated by T-FACE. Summer-planted crops failed. Regressions against season-long average air temperature revealed a lethal temperature of 32°C or higher.