Premium
Photosynthesis and stomatal conductance responses of poplars to free‐air CO 2 enrichment (PopFACE) during the first growth cycle and immediately following coppice
Author(s) -
Bernacchi C. J.,
Calfapietra C.,
Davey P. A.,
Wittig V. E.,
ScarasciaMugnozza G. E.,
Raines C. A.,
Long S. P.
Publication year - 2003
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.2003.00850.x
Subject(s) - photosynthesis , stomatal conductance , coppicing , botany , carboxylation , horticulture , biology , chemistry , woody plant , catalysis , biochemistry
Summary• Using the Poplar Free Air CO 2 Enrichement (PopFACE) facility we investigated the effects of elevated [CO 2 ] 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 ( V c,max ) and maximum rates of electron transport ( J max ) were determined by gas exchange measurement.• Light saturated ( A sat ) and daily integrated ( A ′) photosynthesis increased at elevated [CO 2 ] in all species. Elevated [CO 2 ] decreased V c,max and J max for P. nigra and J max 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 [CO 2 ] did not increase A sat in P. nigra and P. × euramericana due to large decreases in V c,max and J max .• A 50% increase in [CO 2 ] under these open‐air field conditions resulted in a large and sustained increase in A sat . Although there were some differences between the species, these had little effect on photosynthetic rates at the growth [CO 2 ]. 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 [CO 2 ].