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Photosynthetic responses of two eucalypts to industrial‐age changes in atmospheric [CO 2 ] and temperature
Author(s) -
GHANNOUM OULA,
PHILLIPS NATHAN G.,
SEARS MARIE A.,
LOGAN BARRY A.,
LEWIS JAMES D.,
CONROY JANN P.,
TISSUE DAVID T.
Publication year - 2010
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.1365-3040.2010.02172.x
Subject(s) - photosynthesis , acclimatization , carboxylation , horticulture , carbon dioxide , botany , chemistry , eucalyptus , biology , biochemistry , catalysis , organic chemistry
The unabated rise in atmospheric [CO 2 ] is associated with increased air temperature. Yet, few CO 2 ‐enrichment studies have considered pre‐industrial [CO 2 ] or warming. Consequently, we quantified the interactive effects of growth [CO 2 ] and temperature on photosynthesis of faster‐growing Eucalyptus saligna and slower‐growing E. sideroxylon . Well‐watered and ‐fertilized tree seedlings were grown in a glasshouse at three atmospheric [CO 2 ] (290, 400, and 650 µ L L −1 ), and ambient (26/18 °C, day/night) and high (ambient + 4 °C) air temperature. Despite differences in growth rate, both eucalypts responded similarly to [CO 2 ] and temperature treatments with few interactive effects. Light‐saturated photosynthesis ( A sat ) and light‐ and [CO 2 ]‐saturated photosynthesis ( A max ) increased by ∼50% and ∼10%, respectively, with each step‐increase in growth [CO 2 ], underpinned by a corresponding 6–11% up‐regulation of maximal electron transport rate ( J max ). Maximal carboxylation rate ( V cmax ) was not affected by growth [CO 2 ]. Thermal photosynthetic acclimation occurred such that A sat and A max were similar in ambient‐ and high‐temperature‐grown plants. At high temperature, the thermal optimum of A sat increased by 2–7 °C across [CO 2 ] treatments. These results are the first to suggest that photosynthesis of well‐watered and ‐fertilized eucalypt seedlings will remain strongly responsive to increasing atmospheric [CO 2 ] in a future, warmer climate.