What the study found
The study found that canopy temperature in wheat changed strongly across the day and across growth stages, and that the best time to measure it depended on whether plants were rainfed or irrigated. It also found that a single measurement time can miss short heat events and can give an incomplete picture of thermal status.
Why the authors say this matters
The authors conclude that multi-temporal phenotyping, meaning repeated temperature measurements over time, is needed for breeding and physiological interpretation under drought and heat. They also suggest that context-specific measurement windows are important because the optimal time for discrimination changed with environment and stage.
What the researchers tested
The researchers measured wheat canopy temperature (the temperature of the plant canopy) across different hours of the day, growth stages, and environments under Mediterranean conditions. They compared rainfed and irrigated conditions, analyzed variance components, examined clustering and alluvial patterns, and modeled canopy temperature responses to vapor pressure deficit, a measure of how dry and demanding the air is for water loss.
What worked and what didn't
Genotypic discrimination peaked around mid-afternoon, near 15:00, under rainfed conditions, while under irrigation the best window shifted with stage to about 13:30-15:00. Variance-component analyses showed a strong genetic signal, with 87.6-97.7% of total variance attributable to genotypic effects pooled across hours. Genotype rankings were less stable across hours under rainfed conditions, CT > 32 °C depended strongly on time of day and stage, and CT-vapor pressure deficit sensitivity was largely environment-dependent with weak cross-environment correspondence (Spearman ρ = -0.166).
What to keep in mind
The abstract does not describe specific limitations beyond noting that single-time-point phenotyping is incomplete. The reported findings are based on wheat breeding under Mediterranean conditions, so the scope in the abstract is limited to that context.
Key points
- Canopy temperature in wheat varied strongly by hour of day and growth stage.
- The optimal measurement window depended on environment: rainfed plants peaked around 15:00, while irrigated plants peaked around 13:30-15:00 depending on stage.
- Most variance in canopy temperature was attributed to genotypic effects, at 87.6-97.7% across hours.
- Canopy temperatures above 32 °C depended strongly on time of day and stage, and maximum values captured short heat events missed by daily means.
- Genotype rankings changed more across hours under rainfed conditions, showing within-day re-ranking.
- CT-vapor pressure deficit sensitivity varied by environment and showed weak cross-environment correspondence.
Disclosure
- Research title:
- Wheat canopy temperature varies by time of day and growth stage
- Authors:
- Jesús Flores-Olave, Hamza-Ali Khan, Isadora Pérez, Josefa Pacheco, José Cares, Carlos Araya-Riquelme, Felipe Moraga, Ivan T. Matus, Dalma Castillo, Luis Inostroza, Manuel A. Bravo, Hanns de la Fuente-Mella, Gonzalo Ríos-Vásquez, Alejandro del Pozo, Gustavo A. Lobos
- Institutions:
- Instituto de Investigaciones Agropecuarias, Instituto de Investigaciones Agropecuarias, Instituto de Investigaciones Agropecuarias, Pontificia Universidad Católica de Valparaíso, Pontificia Universidad Católica de Valparaíso, Pontificial Catholic University of Valparaiso, Universidad Andrés Bello, University of Talca, University of Talca, University of Talca, University of Talca, University of Talca, University of Talca, University of Talca
- Publication date:
- 2026-03-05
- OpenAlex record:
- View
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