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Root hydraulic conductivity of Larrea tridentata and Helianthus annuus under elevated CO 2
Author(s) -
HUXMAN K. A.,
SMITH S. D.,
NEUMAN D. S.
Publication year - 1999
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 - 10.1046/j.1365-3040.1999.00430.x
Subject(s) - larrea , transpiration , helianthus annuus , shoot , stomatal conductance , perennial plant , horticulture , botany , photosynthesis , chemistry , biology , sunflower , shrub
While investigations into shoot responses to elevated atmospheric CO 2 are extensive, few studies have focused on how an elevated atmospheric CO 2 environment might impact root functions such as water uptake and transport. Knowledge of functional root responses may be particularly important in ecosystems where water is limiting if predictions about global climate change are true. In this study we investigated the effect of elevated CO 2 on the root hydraulic conductivity ( L p ) of a C 3 perennial, Larrea tridentata , and a C 3 annual, Helianthus annuus. The plants were grown in a glasshouse under ambient (360 μ mol mol –1 ) and elevated (700 μ mol mol –1 ) CO 2 . The L p through intact root systems was measured using a hydrostatic pressure‐induced flow system. Leaf gas exchange was also determined for both species and leaf water potential ( ψ leaf ) was determined in L. tridentata . The L p of L. tridentata roots was unchanged by an elevated CO 2 growth environment. Stomatal conductance ( g s ) and transpiration ( E ) decreased and photosynthetic rate ( A net ) and Ψ leaf increased in L. tridentata . There were no changes in biomass, leaf area, stem diameter or root : shoot ( R : S ) ratio for L. tridentata . In H. annuus, elevated CO 2 induced a nearly two‐fold decrease in root L p . There was no effect of growth under elevated CO 2 on A net , g s , E , above‐ and below‐ground dry mass, R : S ratio, leaf area, root length or stem diameter in this species. The results demonstrate that rising atmospheric CO 2 can impact water uptake and transport in roots in a species‐specific manner. Possible mechanisms for the observed decrease in root L p in H. annuus under elevated CO 2 are currently under investigation and may relate to either axial or radial components of root L p .