The upper homeostatic range for the temperature-yield response of irrigated US wheat down revised from a theoretical and experimental perspective

Authors: WECHSUNG, FRANK - Potsdam Institute; RITTER, MATTHIAS - Humboldt University; Wall, Gerard - Gary

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2021
Publication Date: 6/10/2021
Citation: Wechsung, F., Ritter, M., Wall, G.W. 2021. The upper homeostatic range for the temperature-yield response of irrigated US wheat down revised from a theoretical and experimental perspective. Agricultural and Forest Meteorology. 307. Article 108478. https://doi.org/10.1016/j.agrformet.2021.108478.
DOI: https://doi.org/10.1016/j.agrformet.2021.108478

Interpretive Summary: Drought and heat stress adversely affect marketable yield in cereal grain crops. Under adverse environmental conditions, statistical simulation models have been useful tools to estimate these potential yield losses. Nevertheless, the predictive capabilities of these models are data dependent, which has been mostly limited to the temperature range observed during a normal growing season. These simulated predictions do not include temperatures ranges at near-lethal and lethal levels, as projected under global warming. A conclusion that has been derived from such a simulation study is that a well-watered cereal grain crop could overcome temperature-related yield losses projected under global warming. In our novel modelling approach, we made model modifications and used published experimental data instead of data from yield trials. These experimental data not only contained temperature ranges observed during a normal growing season, but also those at near-lethal to lethal levels. We determined that a statistical modelling approach that does not reflect the effects of higher temperatures, including near-lethal to lethal ones during the growing season would overestimate the advantageous effect of irrigation on reducing temperature-related yield losses. Hence, the adverse effects of heat stress on important agricultural crops grown under higher temperatures, which are projected under global warming, cannot be compensated by adequate irrigation alone. The proposed alternative statistical model reported should enable a more reasonable estimation of temperature-related yield losses due to projected global warming in future climate change assessments.

Technical Abstract: High temperature (HT) and drought (D) have detrimental effects on growth and phenology that result in reductions of the yields of agricultural crops. Nevertheless, homeostatic ranges of tolerance exist. Recent analysis of smvey data and simulations suggest US wheat (Triticum aestivwn L.) yields remain relatively stable under irrigation in the range of 35° - 40°C. Applying analogue statistical procedures on experimental data and simulations from the Hot Serial Cereal Experiment (HSC) we demonstrate that failed incorporation of the corresponding phenological acceleration due to HT and a low interannual temperature variability lead to this result. Here, we incorporate the phenological effect into the used binned temperature exposure yield model by rescaling (normalizing) the absolute seasonal temperature counts to a maximum season length. The application to obse1ved and simulated HSC data with a wide temperature range reveals that the suggested upper ho­meostatic response limit of US wheat yields to HT requires a down-revision. HT stress can be reduced by transpirational cooling. However, the effect is currently not sufficient to expand the homeostatic range of irrigated wheat markedly beyond 25°C taking our analysis of the HSC experiment.