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Leaf gas exchange and carbon isotope composition responses to drought in a drought‐avoiding ( Pinus pinaster ) and a drought‐tolerant ( Quercus petraea ) species under present and elevated atmospheric CO 2 concentrations
Author(s) -
PICON C.,
GUEHL J. M.,
FERHI A.
Publication year - 1996
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.1365-3040.1996.tb00239.x
Subject(s) - quercus petraea , pinus pinaster , stomatal conductance , water use efficiency , botany , carbon dioxide , isotopes of carbon , chemistry , deserts and xeric shrublands , horticulture , photosynthesis , biology , environmental chemistry , ecology , total organic carbon , habitat
The responses of predawn leaf water potential (φ wp ), leaf conductance to water vapour diffusion ( g ), CO 2 assimilation rate ( A ) and carbon isotope competition (δ 13 C) to a soil drying cycle were assessed in Pinus pinaster , a drought‐avoiding species with high stomatal sensitivity to drought, and Quercus petraea , a drought‐tolerant species with lower stomatal sensitivity to drought, under present (350 μmol −1 ) and elevated (700 μmol −1 ) atmospheric CO 2 concentrations ([CO 2 ]). In P. pinaster , decreasing A in response to drought was associated with increasing plant intrinsic water use efficiency ( A/g ) and with decreasing calculated intercellular [CO 2 ] ( C 1 ), suggesting a stomatal limitation of A. In contrast, in Q. petraea, A/g declined and C 1 increased during the drying cycle, which suggests a non‐stomatal origin for the decrease in A. In P. pinaster , a negative relationship was observed between the gas exchange‐derived values of C i / C a and δ 13 C, which conforms to the classical two‐step carbon isotope discrimination model. In Q. petraea , the relationship between C 1 /C a and δ 13 C was positive. Possible causes of this discrepancy are discussed. Lower g values were observed under elevated [CO 2 ] than under present [CO 2 ] in Q. petraea , whereas g was unaffected in P. pinaster . A stimulation of A by elevated [CO 2 ] was found in P. pinaster but not in Q. petraea . In both species, A/g was markedly higher under elevated than under present [CO 2 ]. Whether the differences in the g response to elevated [CO 2 ] found here can be generalized to other drought‐avoiding and non‐avoiding species remains to be assessed.