Stress indicators based on airborne thermal imagery for field phenotyping a heterogeneous tree population for response to water constraints

Virlet Nicolas, Lebourgeois Valentine, Martinez Sébastien, Costes Evelyne, Labbé Sylvain, Regnard Jean-Luc. 2014. Stress indicators based on airborne thermal imagery for field phenotyping a heterogeneous tree population for response to water constraints. Journal of Experimental Botany, 65 (18) : 5429-5442.

Quartile : Outlier, Sujet : PLANT SCIENCES

Résumé : As field phenotyping of plant response to water constraints constitutes a bottleneck for breeding programmes, airborne thermal imagery can contribute to assessing the water status of a wide range of individuals simultaneously. However, the presence of mixed soil-plant pixels in heterogeneous plant cover complicates the interpretation of canopy temperature. Moran's Water Deficit Index (WDI = 1-ETact/ETmax), which was designed to overcome this difficulty, was compared with surface minus air temperature (Ts-Ta) as a water stress indicator. As parameterization of the theoretical equations for WDI computation is difficult, particularly when applied to genotypes with large architectural variability, a simplified procedure based on quantile regression was proposed to delineate the Vegetation Index-Temperature (VIT) scatterplot. The sensitivity of WDI to variations in wet and dry references was assessed by applying more or less stringent quantile levels. The different stress indicators tested on a series of airborne multispectral images (RGB, near-infrared, and thermal infrared) of a population of 122 apple hybrids, under two irrigation regimes, significantly discriminated the tree water statuses. For each acquisition date, the statistical method efficiently delineated the VIT scatterplot, while the limits obtained using the theoretical approach overlapped it, leading to inconsistent WDI values. Once water constraint was established, the different stress indicators were linearly correlated to the stem water potential among a tree subset. Ts-Ta showed a strong sensitivity to evaporative demand, which limited its relevancy for temporal comparisons. Finally, the statistical approach of WDI appeared the most suitable for high-throughput phenotyping.

Mots-clés Agrovoc : Malus pumila, stress dû à la sécheresse, phénotype, télédétection, imagerie, température de l'air, bilan hydrique, évapotranspiration, indice de surface foliaire, culture fruitière, physiologie végétale, fruits tempérés

Mots-clés géographiques Agrovoc : Languedoc-Roussillon, France

Classification Agris : F62 - Physiologie végétale - Croissance et développement
H50 - Troubles divers des plantes
F70 - Taxonomie végétale et phytogéographie

Champ stratégique Cirad : Axe 1 (2014-2018) - Agriculture écologiquement intensive

Auteurs et affiliations

• Virlet Nicolas, CIRAD-BIOS-UMR AGAP (FRA)
• Lebourgeois Valentine, CIRAD-ES-UMR TETIS (REU)
• Martinez Sébastien, INRA (FRA)
• Costes Evelyne, INRA (FRA)
• Labbé Sylvain, IRSTEA (FRA)
• Regnard Jean-Luc, Montpellier SupAgro (FRA)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/573938/)

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