Photosynthesis and Stomatal Conductance Responses of Poplars to Free-Air CO2 Enrichment (PopFACE) during the First Growth Cycle and Immediately Following Coppice

• Using the Poplar Free Air CO2 Enrichement (PopFACE) facility we investigated the effects of elevated [ CO2] on the diurnal and growth cycle responses of photosynthesis and conductance in three poplar species. • In situ diurnal measurements of photosynthesis were made on Populus alba, P. nigra and...

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Veröffentlicht in:The New phytologist 2003-09, Vol.159 (3), p.609-621
Hauptverfasser: Bernacchi, C. J., Calfapietra, C., Davey, P. A., Wittig, V. E., Scarascia-Mugnozza, G. E., Raines, C. A., Long, S. P.
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Sprache:eng
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Zusammenfassung:• Using the Poplar Free Air CO2 Enrichement (PopFACE) facility we investigated the effects of elevated [ CO2] on the diurnal and growth cycle responses of photosynthesis and conductance in three poplar species. • In situ diurnal measurements of photosynthesis were made on Populus alba, P. nigra and P. × euramericana and, in parallel, in vivo maximum capacity for carboxylation (Vc,max) and maximum rates of electron transport (Jmax) were determined by gas exchange measurement. • Light saturated (Asat) and daily integrated (A′) photosynthesis increased at elevated [ CO2] in all species. Elevated [ CO2] decreased Vc,max and Jmax for P. nigra and Jmax for P. × euramericana but had no effect on stomatal conductance in any of the species throughout the first growth cycle. During post-coppice re-growth, elevated [ CO2] did not increase Asat in P. nigra and P. × euramericana due to large decreases in Vc,max and Jmax. • A 50% increase in [ CO2] under these open-air field conditions resulted in a large and sustained increase in Asat. Although there were some differences between the species, these had little effect on photosynthetic rates at the growth [ CO2]. Nevertheless the results show that even fast growing trees grown without rooting volume restriction in the open may still show some down-regulation of photosynthetic potential at elevated [ CO2].
ISSN:0028-646X
1469-8137
DOI:10.1046/j.1469-8137.2003.00850.x