Wheat response to a wide range of temperatures, as determined from the Hot Serial Cereal (HSC) Experiment

Abstract

Temperatures are warming on a global scale, a phenomenon that likely will affect future crop productivity. 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 such 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) system (Hot) were deployed over one-third of the plots to warm the wheat by additional target 1.5°C during daytime and 3.0°C at night. Achieved average degrees of warming were 1.3 and 2.7°C for day and night. Overall, a dataset covering 27 differently treated wheat crops with three replicates each was obtained covering an air temperature range from-2 to 42°C. Herein, the management, soils, weather, physiology, phenology, growth, yield, quality, and other data are presented. 1 OBJECTIVE: The primary objective was to obtain a dataset on the response of wheat to a wide range of temperatures. This was achieved by planting the wheat serially about every six weeks for over two years at Maricopa, Arizona, which experiences temperatures from below freezing to higher than most places on Earth where wheat is grown. In addition, on six of the planting dates, infrared heaters in a temperature free-air controlled enhancement (T-FACE) system were deployed so as to provide a treatment wherein only the crop temperature was varied with respect to reference and control treatments. 2 FIELD EXPERIMENTS: Approximately every six weeks for over two years starting in March, 2007, the bread wheat (Triticum aestivum L.) cultivar Yecora Rojo (Qualset et al., 1985) was planted in a Hot Serial Cereal (HSC) experiment conducted at Maricopa, Arizona, USA. There were a total of 15 planting dates For six of the plantings (early fall, midwinter, and spring), infrared heater arrays (T-FACE) were deployed in a Latin square experimental design with three replicates each of Heated plots, Reference plots with dummy heaters (i.e., the same housing as real heaters, but no heating elements), and Control plots with no experimental apparatus. As described by Kimball et al. (2008), the plots were 3 m in diameter, and calibrated infrared thermometers were used to measure canopy temperatures in the Heated and Reference plots. The canopy temperature data were processed by dataloggers, which provided 0-10 V control signals to dimmers, which in turn modulated the output of the heaters {[Model FTE-1000 (1000 W, 240 V, 245 mm long x 60 mm wide)] mounted in reflector housings, so as to maintain the canopy temperatures of the Heated plots at 1.5°C warmer than those of the Reference plots during daytime and 3.0°C warmer at night. Additional experimental details are presented in Wall et al. Solar radiation, air temperature, and wind speed were measured on a weather mast in the experimental field most of the time starting with the fall, 2007 planting. For times when field mast data were not available, we utilized data from the AZMET weather station (http://ag.arizona.edu/AZMET/) located about 1 km away.