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

Authors: KIMBALL, BRUCE - Former ARS Employee; White, Jeffrey; Wall, Gerard - Gary; OTTMAN, M - University Of Arizona

Submitted to: American Society of Agronomy Monograph Series
Publication Type: Book / Chapter
Publication Acceptance Date: 10/7/2014
Publication Date: 1/14/2016
Citation: Kimball, B.A., White, J.W., Wall, G.W., Ottman, M.J. 2016. Wheat responses to a wide range of temperatures: The hot serial cereal experiment. In:Haatfield, J.L., Fleisher, D., editors. Improving Modeling Tools to Assess Climate Change Effects on Crop Response. Advances in Agricultural Systems Modeling, Volume 7.American Society of Agronomy Monograph Series. In: Ahuja, L.R., series editor.Madison,WI:ASA, CSSA, SSSA. p. 1-12.

Interpretive Summary: Wheat growth models are useful tools for assessing the likely effects of climate change on future productivity, but they generally have not been tested at the higher temperatures expected in the future. In order to obtain data suitable for testing these models, a “Hot Serial Cereal” experiment was conducted – “Cereal” because it was on wheat, “Serial” because the wheat was planted serially approximately every six weeks for two years, and “Hot” because on three of the planting dates each year, infrared heaters were deployed above the crop to warm it by 1.5°C (2.7°F) during daytime and 3.0°C (5.4°F) at night. The results showed that for normal planting dates (Dec.-Jan.), the extra infrared heating had no significant effect on the wheat growth. For late-planted wheat (Mar.) yields were generally depressed because of the shortened growing season, and the extra warming from the heaters exacerbated the yield depression. In marked contrast, for early-planted wheat (Sep.), mid-winter frosts reduced yields of unheated plots to zero, whereas the wheat under the heaters had yields only slightly depressed compared to the optimally planted wheat. Summer-planted crops failed. Thus, an excellent dataset was obtained suitable for testing wheat models over the whole range of temperatures at which wheat can grow. This research will benefit all consumers of wheat-based food, including meat from animals that are fed wheat.

Technical Abstract: 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, a “Hot Serial Cereal” experiment was conducted on wheat (Triticum aestivum L.), the world’s foremost food and feed crop, in order to obtain a dataset appropriate for testing the high temperature performance of wheat growth models. The wheat (Cereal) was planted serially (Serial) about every six weeks for over two years at Maricopa, Arizona, USA, which experiences the whole range of temperatures at which plants grow on Earth. In addition, on six planting dates infrared heaters in a T-FACE (temperature free-air controlled enhancement) (Hot) system were deployed over 1/3 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 zero to 800 g m-2. Crops planted in mid-winter (normal planting time) yielded 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.