Measuring photosynthesis of entire tree crowns and pulse label trees in large closed chamber with 13co2 in the field: Design and testing

Duangngam Onouma, Sathornkich Jate, Thaler Philippe, Chayawat Chompunut, Phattaralerphong Jessada, Chantuma Pisamai, Priault Pierrick, Desalme Dorine, Satakhun Duangrat, Kayankit Phetrada, Kasemsap Poonpipope, Epron Daniel. 2023. Measuring photosynthesis of entire tree crowns and pulse label trees in large closed chamber with 13co2 in the field: Design and testing. Trends in Sciences, 20 (12):6926, 11 p.

Résumé : Measuring the photosynthesis of entire tree crowns and pulse labelling trees with 13CO2 are valuable approaches to study carbon acquisition, transfer, and allocation; however, it is challenging for trees in the field. The objective was to develop and field test large chambers (35 - 45 m3) that enclosed the entire crown of a tree, provided a reliable estimate of tree crown photosynthesis, and ensured efficient 13CO2 labelling. The chambers, made of transparent polyethylene film pulled tightly over a frame, were equipped with an air conditioner, fans, and air blowers. Air temperature, relative humidity, and photosynthetic photon flux density were measured outside and inside each chamber. Six of 4-year-old rubber trees (Hevea brasiliensis) were pulsed-labelled with 18 L of 13CO2 in June and October 2016. The mean air temperature inside the chambers was 1.2 °C higher and the relative humidity 8 % lower than the outside air. The crown photosynthesis, calculated from the decrease in the CO2 concentration inside the chamber, was in the range 140 - 249 µmol s–1 and was significantly related to photosynthetic photon flux density, total leaf area of the tree, and average net CO2 assimilation at leaf level. The labelling efficiency, estimated as the ratio of the amount of 13C recovered in the foliage immediately after labelling divided by the amount of 13C delivered to the tree, was in the range 43 - 68 %. The designed chamber was suitable to estimate crown photosynthesis and perform 13CO2 pulse labelling of 5-m-tall trees in the field.

Mots-clés Agrovoc : Hevea brasiliensis, photosynthèse, dioxyde de carbone, Houppier, échange gazeux, mesure (activité), changement climatique, film de polyéthylène, légume sec, latex, chambre de décompression, Conditionneur d'air, polyéthylène, carbone

Mots-clés géographiques Agrovoc : Thaïlande

Mots-clés libres : CO2 labelling, Hevea brasiliensis, Carbon stable isotope, Rubber trees, Whole crown net CO2 exchange rate

Classification Agris : F60 - Physiologie et biochimie végétale
F40 - Écologie végétale

Champ stratégique Cirad : CTS 2 (2019-) - Transitions agroécologiques

Agences de financement hors UE : Agence Nationale de la Recherche, Institut Français du Caoutchouc, Kasetsart University, Kasetsart University Research Development Institute, Center of Thai-French Cooperation on Higher Education and Research

Projets sur financement : (FRA) Comment les plantations familiales peuvent-elles s'adapter aux changements globaux?

Auteurs et affiliations

• Duangngam Onouma, Kasetsart University (THA) - auteur correspondant
• Sathornkich Jate, Kasetsart University (THA)
• Thaler Philippe, CIRAD-PERSYST-UMR Eco&Sols (FRA) ORCID: 0000-0002-9924-4309
• Chayawat Chompunut, Geo-Informatics and Space Technology Development Agency (THA)
• Phattaralerphong Jessada, Kasetsart University (THA)
• Chantuma Pisamai, Chachoengsao Rubber Research Center (THA)
• Priault Pierrick, Université de Lorraine (FRA)
• Desalme Dorine, Université de Lorraine (FRA)
• Satakhun Duangrat, Kasetsart University (THA)
• Kayankit Phetrada, Kasetsart University (THA)
• Kasemsap Poonpipope, Kasetsart University (THA)
• Epron Daniel, Université de Lorraine (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/606540/)

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