title: Elevated atmospheric CO2 concentration leads to increased whole-plant isoprene emission in hybrid aspen (Populus tremula × Populus tremuloides).
abstract: Effects of elevated atmospheric [CO2] on plant isoprene emissions are controversial. Relying on leaf-scale measurements, most models simulating isoprene emissions in future higher [CO2] atmospheres suggest reduced emission fluxes. However, combined effects of elevated [CO2] on leaf area growth, net assimilation and isoprene emission rates have rarely been studied on the canopy scale, but stimulation of leaf area growth may largely compensate for possible [CO2] inhibition reported at the leaf scale. This study tests the hypothesis that stimulated leaf area growth leads to increased canopy isoprene emission rates. We studied the dynamics of canopy growth, and net assimilation and isoprene emission rates in hybrid aspen (Populus tremula × Populus tremuloides) grown under 380 and 780 μmol mol(-1) [CO2]. A theoretical framework based on the Chapman-Richards function to model canopy growth and numerically compare the growth dynamics among ambient and elevated atmospheric [CO2]-grown plants was developed. Plants grown under elevated [CO2] had higher C : N ratio, and greater total leaf area, and canopy net assimilation and isoprene emission rates. During ontogeny, these key canopy characteristics developed faster and stabilized earlier under elevated [CO2]. However, on a leaf area basis, foliage physiological traits remained in a transient state over the whole experiment. These results demonstrate that canopy-scale dynamics importantly complements the leaf-scale processes, and that isoprene emissions may actually increase under higher [CO2] as a result of enhanced leaf area production.
authors: Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, Tartu, 51014, Estonia.
authors: Zhihong
authors: Z
authors: Sun
authors: Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, Tartu, 51014, Estonia.
authors: Ülo
authors: Ü
authors: Niinemets
authors: Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, Tartu, 51014, Estonia.
authors: Katja
authors: K
authors: Hüve
authors: Institute of Molecular and Cell Biology, University of Tartu, Riia 23, Tartu, 510101, Estonia.
authors: Bahtijor
authors: B
authors: Rasulov
authors: Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, Tartu, 51014, Estonia.
authors: Steffen M
authors: SM
authors: Noe
mesh_terms: D001272:Atmosphere; D002070:Butadienes / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000494:pharmacology; D002678:Chimera; D057231:Climate Change; D045782:Hemiterpenes / Q000378:metabolism*; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism; D010420:Pentanes / Q000378:metabolism*; D018515:Plant Leaves / Q000502:physiology; D032107:Populus / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*
chemical_list: D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; C005059:isoprene; D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen