No evidence of homeostatic regulation of leaf temperature in Eucalyptus parramattensis trees integration of CO2 flux and oxygen isotope methodologies

No evidence of homeostatic regulation of leaf temperature in Eucalyptus parramattensis trees : integration of CO2 flux and oxygen isotope methodologies

© 2020 The Authors. New Phytologist © 2020 New Phytologist Foundation.

Bibliographische Detailangaben
Veröffentlicht in:The New phytologist. - 1979. - 228(2020), 5 vom: 21. Dez., Seite 1511-1523
1. Verfasser: Drake, John E (VerfasserIn)
Weitere Verfasser: Harwood, Richard, Vårhammar, Angelica, Barbour, Margaret M, Reich, Peter B, Barton, Craig V M, Tjoelker, Mark G
Format: Online-Aufsatz
Sprache:English
Veröffentlicht: 2020
Zugriff auf das übergeordnete Werk:The New phytologist
Schlagworte:Journal Article Research Support, Non-U.S. Gov't Eucalyptus parramattensis carbon cycle climate warming endothermy photosynthesis temperature regulation Oxygen Isotopes Carbon Dioxide 142M471B3J
Beschreibung
Zusammenfassung:© 2020 The Authors. New Phytologist © 2020 New Phytologist Foundation.
Thermoregulation of leaf temperature (Tleaf ) may foster metabolic homeostasis in plants, but the degree to which Tleaf is moderated, and under what environmental contexts, is a topic of debate. Isotopic studies inferred the temperature of photosynthetic carbon assimilation to be a constant value of c. 20°C; by contrast, leaf biophysical theory suggests a strong dependence of Tleaf on environmental drivers. Can this apparent disparity be reconciled? We continuously measured Tleaf and whole-crown net CO2 uptake for Eucalyptus parramattensis trees growing in field conditions in whole-tree chambers under ambient and +3°C warming conditions, and calculated assimilation-weighted leaf temperature (TL-AW ) across 265 d, varying in air temperature (Tair ) from -1 to 45°C. We compared these data to TL-AW derived from wood cellulose δ18 O. Tleaf exhibited substantial variation driven by Tair , light intensity, and vapor pressure deficit, and Tleaf was strongly linearly correlated with Tair with a slope of c. 1.0. TL-AW values calculated from cellulose δ18 O vs crown fluxes were remarkably consistent; both varied seasonally and in response to the warming treatment, tracking variation in Tair . The leaves studied here were nearly poikilothermic, with no evidence of thermoregulation of Tleaf towards a homeostatic value. Importantly, this work supports the use of cellulose δ18 O to infer TL-AW , but does not support the concept of strong homeothermic regulation of Tleaf
Beschreibung:Date Completed 26.04.2021
Date Revised 26.04.2021
published: Print-Electronic
CommentIn: New Phytol. 2020 Dec;228(5):1455-1457. - PMID 33011978
Citation Status MEDLINE
ISSN:1469-8137
DOI:10.1111/nph.16733