Preprints
https://doi.org/10.5194/hess-2020-549
https://doi.org/10.5194/hess-2020-549

  28 Oct 2020

28 Oct 2020

Review status: a revised version of this preprint was accepted for the journal HESS and is expected to appear here in due course.

Canopy temperature and heat stress are increased by compound high air temperature and water stress, and reduced by irrigation – A modeling analysis

Xiangyu Luan and Giulia Vico Xiangyu Luan and Giulia Vico
  • Department of Crop Production Ecology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden

Abstract. Crop yield is reduced by heat and water stress, and even more when they co-occur. Yet, compound effects of air temperature and water availability on crop heat stress are poorly quantified: crop models, by relying at least partially on empirical functions, cannot account for the feedbacks of plant traits and response to heat and water stress on canopy temperature. We developed a fully mechanistic model coupling crop energy and water balances, to determine canopy temperature as a function of plant traits, stochastic environmental conditions and their variability; and irrigation applications. While general, the model was parameterized for wheat. Canopy temperature largely followed air temperature under well-watered conditions; but when soil water potential was more negative than −0.14 MPa, further reductions in soil water availability led to a rapid rise in canopy temperature – up to 10 °C warmer than air at soil water potential of −0.62 MPa. More intermittent precipitation led to higher canopy temperatures and longer periods of potentially damaging crop canopy temperatures. Irrigation applications aimed at keeping crops under well-watered conditions could reduce canopy temperature, but in most cases were unable to maintain it below the threshold temperature for potential heat damage; the benefits of irrigation became smaller as average air temperature increased. Hence, irrigation is only a partial solution to adapt to warmer and drier climates.

Xiangyu Luan and Giulia Vico

 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Xiangyu Luan and Giulia Vico

Xiangyu Luan and Giulia Vico

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Short summary
Crop yield is reduced by heat and water stress, in particular when they co-occur. We quantify the joint effects of the (unpredictable) air temperature and water availability on crop heat stress via a mechanistic model. Larger but more infrequent rainfalls increased crop canopy temperatures. Keeping crops well watered via irrigation could reduce canopy temperature, but not enough to exclude heat damage. Thus, irrigation is only a partial solution to adapt to warmer and drier climates.