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Ontogeny and leaf gas exchange mediate the carbon isotopic signature of herbaceous plants
Author(s) -
SALMON YANN,
BARNARD ROMAIN L.,
BUCHMANN NINA
Publication year - 2011
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2010.02256.x
Subject(s) - ontogeny , biology , photorespiration , herbaceous plant , photosynthesis , respiration , botany , isotopes of carbon , stomatal conductance , ecology , genetics , total organic carbon
Values (Δ i ) predicted by a simplified photosynthetic discrimination model, based only on diffusion through air followed by carboxylation, are often used to infer ecological conditions from the 13 C signature of plant organs ( δ 13 C p ). Recent studies showed that additional isotope discrimination ( d that includes mesophyll conductance, photorespiration and day respiration, and post‐carboxylation discrimination) can strongly affect δ 13 C p ; however, little is known about its variability during plant ontogeny for different species. Effect of ontogeny on leaf gas exchange rates, Δ i , observed discrimination (Δ p ) and d in leaf, phloem and root of seven herbaceous species at three ontogenetic stages were investigated under controlled conditions. Functional group identity and ontogeny significantly affected Δ i and Δ p . However, predicted Δ i did not match Δ p . d , strongly affected by functional group identity and ontogeny, varied by up to 14‰. d scaled tightly with stomatal conductance, suggesting complex controls including changes in mesophyll conductance. The magnitude of the changes in δ 13 C p due to ontogeny was similar to that due to environmental factors reported in other studies. d and ontogeny should, therefore, be considered in ecosystem studies, integrated in ecosystem models using δ 13 C p and limit the applicability of δ 13 C leaf as a proxy for water‐use efficiency in herbaceous plants.