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Transport of root‐respired CO 2 via the transpiration stream affects aboveground carbon assimilation and CO 2 efflux in trees
Author(s) -
Bloemen Jasper,
McGuire Mary Anne,
Aubrey Doug P.,
Teskey Robert O.,
Steppe Kathy
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2012.04366.x
Subject(s) - transpiration , transpiration stream , xylem , respiration , botany , assimilation (phonology) , carbon dioxide , biology , photosynthesis , autotroph , photorespiration , woody plant , salicaceae , chemistry , ecology , linguistics , philosophy , genetics , bacteria
Summary Upward transport of CO 2 via the transpiration stream from belowground to aboveground tissues occurs in tree stems. Despite potentially important implications for our understanding of plant physiology, the fate of internally transported CO 2 derived from autotrophic respiratory processes remains unclear. We infused a 13 CO 2 ‐labeled aqueous solution into the base of 7‐yr‐old field‐grown eastern cottonwood ( Populus deltoides ) trees to investigate the effect of xylem‐transported CO 2 derived from the root system on aboveground carbon assimilation and CO 2 efflux. The 13 C label was transported internally and detected throughout the tree. Up to 17% of the infused label was assimilated, while the remainder diffused to the atmosphere via stem and branch efflux. The largest amount of assimilated 13 C was found in branch woody tissues, while only a small quantity was assimilated in the foliage. Petioles were more highly enriched in 13 C than other leaf tissues. Our results confirm a recycling pathway for respired CO 2 and indicate that internal transport of CO 2 from the root system may confound the interpretation of efflux‐based estimates of woody tissue respiration and patterns of carbohydrate allocation.