A simple glasshouse experiment to test the isotopic fractionation in olive trees
Notice bibliographique
Résumé
Plant transpiration is a main component of the global water cycle and plays a key role in regulating ecohydrological process. Stable isotopes of oxygen and hydrogen are often used for the identification and quantification of plant water sources in ecohydrology. However, the isotopic tracing technique assumes that the isotopic signal in the water taken up by the plants remains unaltered during uptake at the soil-roots interface and transport to the distal twigs, i.e., isotopic fractionation does not occur during the water uptake and along the transport pathway. Nevertheless, recent studies showed that isotopic fractionation can occur under different environmental conditions. In this study, we performed a simple experiment with two olive (Olea europaea) trees utilizing labelled water to test isotopic fractionation of plant water during uptake and transport within the plants under controlled conditions. In addition, we performed the cryogenic vacuum distillation in two different laboratories to examine any possible effects of the extraction system on the isotopic composition of plant water extracts. We set up the olive trees in pots inside a glasshouse and measured sap flow rates with Granier thermal dissipation probe, and shallow soil moisture by using a portable soil moisture probe. Air temperature, global solar radiation, and relative humidity were measured by a weather station installed inside the glasshouse nearby the olive trees. We irrigated the two plants with water of known isotopic composition and sampled the twigs, wood cores, roots, and soils at different depths (0-5, 5-15, and 15-25 cm). We extracted plant and soil waters by means of cryogenic vacuum distillation performed in two different laboratories. Our results showed that the plant water samples reflected the isotopic signature of labelled water and mobile soil water, suggesting no isotopic fractionation during water transport. No significant differences were detected for twigs and wood cores extracted from distinct sections of the tree. However, only significant differences were obtained between plant tissue water (twigs, cores) and cryogenically-extracted deep soil water (i.e., >15 cm depths). Furthermore, we found no significant effects of the two cryogenic extraction systems on the isotopic composition of water extracts. Our results indicate that isotopic fractionation might not occur during root water uptake and transport processes in olive trees, at least under the specified experimental conditions, validating the conventional isotope-tracing approach. Further work both in the field and under controlled conditions, and on different plant species, is needed to check for this consistency, as well as testing other plant water extraction methods. Keywords: olive tree; stable isotope analysis; plant water; cryogenic vacuum distillation; fractionation; labelled water.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,002 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».