Rapid spatial assessment of leaf-absorbed irradiance

Jiayu Zhang, Elias Kaiser, Leo Marcelis, Silvere Vialet-Chabrand*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Image-based high-throughput phenotyping promises the rapid determination of functional traits in large plant populations. However, interpretation of some traits – such as those related to photosynthesis or transpiration rates – is only meaningful if the irradiance absorbed by the measured leaves is known, which can differ greatly between different parts of the same plant and within canopies. No feasible method currently exists to rapidly measure absorbed irradiance in three-dimensional plants and canopies. We developed a method and protocols to derive absorbed irradiance at any visible part of a canopy with a thermal camera, by fitting a leaf energy balance model to transient changes in leaf temperature. Leaves were exposed to short light pulses (30 s) that were not long enough to trigger stomatal opening but strong enough to induce transient changes in leaf temperature that was proportional to the absorbed irradiance. The method was successfully validated against point measurements of absorbed irradiance in plant species with relatively simple architecture (sweet pepper, cucumber, tomato, and lettuce). Once calibrated, the model was used to produce absorbed irradiance maps from thermograms. Our method opens new avenues for the interpretation of plant responses derived from imaging techniques and can be adapted to existing high-throughput phenotyping platforms.

Original languageEnglish
Pages (from-to)1866-1876
Number of pages11
JournalNew Phytologist
Issue number4
Early online dateFeb 2024
Publication statusPublished - Feb 2024


  • absorbed irradiance
  • canopy
  • energy balance
  • high-throughput phenotyping
  • thermal imaging


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