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Leaf carbon management in slow‐growing plants exposed to elevated CO 2
Author(s) -
ARANJUELO IKER,
PARDO ANTONI,
BIEL CARMEN,
SAVÉ ROBERT,
AZCÓNBIETO JOAQUIM,
NOGUÉS SALVADOR
Publication year - 2009
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2008.01829.x
Subject(s) - photosynthesis , rubisco , acclimatization , sink (geography) , botany , carbon dioxide , biology , carbon sink , photosynthetic capacity , horticulture , chemistry , ecology , ecosystem , geography , cartography
Two slow‐growing plant species ( Chamaerops humilis , L. and Cycas revoluta Thunb.) were exposed to elevated CO 2 conditions over a 20‐month period in order to study the CO 2 effect on growth, photosynthetic capacity and leaf carbon (C) management. The ambient isotopic 13 C/ 12 C composition ( δ 13 C) of the greenhouse module corresponding to elevated CO 2 (800 μmol mol −1 CO 2 ) conditions was changed from δ 13 C ca. −12.8±0.3‰ to ca. −19.2±0.2‰. Exposure of these plants to elevated CO 2 enhanced dry mass (DM) by 82% and 152% in Chamerops and Cycas , respectively, mainly as a consequence of increases in plant level photosynthetic rates. However, analyses of A – C i curve parameters revealed that elevated CO 2 diminished leaf photosynthetic rates of Chamaerops whereas in Cycas , no photosynthetic acclimation was detected. The fact that Chamaerops plants had a lower DM increase, together with a longer leaf C residence time and a diminished capacity to respire recently fixed C, suggests that this species was unable to increase C sink strength. Furthermore, the consequent C source/sink imbalance in Chamaerops might have induced the downregulation of Rubisco. Cycas plants were capable of avoiding photosynthetic downregulation due to a greater ability to increase C sink strength, as was confirmed by DM values, and 12 C‐enriched CO 2 labeling data. Cycas developed the ability to respire a larger proportion of recently fixed C and to reallocate the recently fixed C away from leaves to other plant tissues. These findings suggest that leaf C management is a key factor in the responsiveness of slow‐growing plants to future CO 2 scenarios.