Journal Article

Determination of leaf respiration in the light

Xiao Ying Gong, Rudi Schäufele, Hans Schnyder, Guillaume Tcherkez, Johannes Wenig

2018

Overview

Quantification of leaf respiration is important for understanding plant physiology and ecosystem biogeochemical processes. Leaf respiration continues in the light (R L) but supposedly at a lower rate than in the dark (R Dk). However, there is no method for direct measurement of R L and the available methods require nonphysiological measurement conditions. A method based on isotopic disequilibrium quantified R L (R L 13C) and mesophyll conductance of young and old fully expanded leaves of six species. R L 13C was compared to R L determined by the Laisk method (R L Laisk) on the very same leaves with a minimum time lag. R L 13C and R L Laisk were generally lower than R Dk, and were not significantly affected by leaf ageing. R L Laisk and R L 13C were positively correlated (r 2 = 0.35), and both were positively correlated with R Dk (r 2 ≥ 0.6). R L Laisk was systematically lower than R L 13C by 0.4 μmol m−2 s−1. Using A/C c instead of A/C i curves, a higher photocompensation point Γ* (by 5 μmol mol−1) was found but no influence on R L Laisk estimates was observed. The results imply that the Laisk method underestimates actual R L significantly, probably related to the measurement condition of low CO2 and irradiance. The isotopic disequilibrium method is useful for assessing responses of R L to irradiance and CO2, improving our mechanistic understanding of R L.

• Publisher: New Phytologist Trust,Wiley Subscription Services, Inc
• Subject: Ageing / Biogeochemistry / Carbon 13 / Carbon dioxide / carbon isotope discrimination / Conductance / correlation / ecosystems / Irradiance / leaf age / Leaves / light intensity / Measurement / Measurement methods / Mesophyll / mesophyll conductance / mitochondrial respiration / photocompensation point / photosynthesis / Plant physiology / Resistance / Respiration / Time lag