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Elevated CO2 protects poplar (Populus trichocarpa x P-deltoides) from damage induced by O3: identification of mechanisms

Elevated CO2 protects poplar (Populus trichocarpa x P-deltoides) from damage induced by O3: identification of mechanisms
Elevated CO2 protects poplar (Populus trichocarpa x P-deltoides) from damage induced by O3: identification of mechanisms
CO2 concentrations in the Earth's atmosphere will rise to between 550 and 700 mu L L-1 by 2100 (IPCC 2001). In much of the world, ozone (O-3) is the air pollutant most likely to be having adverse effects on the growth of plants. Here we describe the impacts of CO2 and O-3 episodes ( rising to 100 nL L-1), singly and in mixtures on the growth and physiology of an interamerican hybrid poplar ( Populus trichocarpa L. (Torr. C Gray ex Hook.) x P. deltoids Bartr. ex Marsh). 700 mu L L-1 CO2 increased all growth variables relative to values in 350 mu L L-1. Mainstem dry weight showed a 38% increase in year 1 and a 32% increase in year 2. Ozone episodes reduced mainstem dry mass by 45% in 350 mu L L-1 CO2 and by 34% in 700 mu L L-1 CO2. A/C-i analysis showed limited effects on photosynthetic efficiency of 700 mu L L-1 CO2 but in contrast, V-cmax was reduced by O-3 episodes. CO2 tended to increase leaf expansion but O-3 episodes reduced expansion rates generally although a short period of increased leaf expansion in response to O-3 was also observed. O-3 reduced leaf solute potentials (Psi s) and increased turgor ( P) in young leaves. Cell wall properties ( elasticity and plasticity) were both stimulated by ozone and this was associated with increased leaf expansion. A new mechanism is proposed which suggests that O-3 may act directly on the cell wall, attacking polysaccharides in the wall that result in altered cell wall properties and leaf growth. O-3 episodes increased leaf loss, elevated CO2 delayed abscission and O-3 was less effective at accelerating leaf loss in elevated CO2. Overall CO2 increased growth, O-3 caused decreases and the treatment combination gave intermediate effects. Thus O-3 episodes are less likely to be detrimental to P. trichocarpa x P. deltoides in the CO2 concentrations of the future.
CO2, O3, leaf growth, water relations, poplar, biomass accumulation
1445-4408
221-235
Gardner, Simon D.Ll
1ccb0390-d75c-4f32-8b62-e61a1daf0fe2
Freer-Smith, Peter H.
553cb4a8-93d0-4ecf-a1f3-fff9c68304fa
Tucker, J.
124febb6-dc7f-4dab-b425-ff3e85c81593
Taylor, Gail
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Gardner, Simon D.Ll
1ccb0390-d75c-4f32-8b62-e61a1daf0fe2
Freer-Smith, Peter H.
553cb4a8-93d0-4ecf-a1f3-fff9c68304fa
Tucker, J.
124febb6-dc7f-4dab-b425-ff3e85c81593
Taylor, Gail
f3851db9-d37c-4c36-8663-e5c2cb03e171

Gardner, Simon D.Ll, Freer-Smith, Peter H., Tucker, J. and Taylor, Gail (2005) Elevated CO2 protects poplar (Populus trichocarpa x P-deltoides) from damage induced by O3: identification of mechanisms. Functional Plant Biology, 32 (3), 221-235. (doi:10.1071/FP04131).

Record type: Article

Abstract

CO2 concentrations in the Earth's atmosphere will rise to between 550 and 700 mu L L-1 by 2100 (IPCC 2001). In much of the world, ozone (O-3) is the air pollutant most likely to be having adverse effects on the growth of plants. Here we describe the impacts of CO2 and O-3 episodes ( rising to 100 nL L-1), singly and in mixtures on the growth and physiology of an interamerican hybrid poplar ( Populus trichocarpa L. (Torr. C Gray ex Hook.) x P. deltoids Bartr. ex Marsh). 700 mu L L-1 CO2 increased all growth variables relative to values in 350 mu L L-1. Mainstem dry weight showed a 38% increase in year 1 and a 32% increase in year 2. Ozone episodes reduced mainstem dry mass by 45% in 350 mu L L-1 CO2 and by 34% in 700 mu L L-1 CO2. A/C-i analysis showed limited effects on photosynthetic efficiency of 700 mu L L-1 CO2 but in contrast, V-cmax was reduced by O-3 episodes. CO2 tended to increase leaf expansion but O-3 episodes reduced expansion rates generally although a short period of increased leaf expansion in response to O-3 was also observed. O-3 reduced leaf solute potentials (Psi s) and increased turgor ( P) in young leaves. Cell wall properties ( elasticity and plasticity) were both stimulated by ozone and this was associated with increased leaf expansion. A new mechanism is proposed which suggests that O-3 may act directly on the cell wall, attacking polysaccharides in the wall that result in altered cell wall properties and leaf growth. O-3 episodes increased leaf loss, elevated CO2 delayed abscission and O-3 was less effective at accelerating leaf loss in elevated CO2. Overall CO2 increased growth, O-3 caused decreases and the treatment combination gave intermediate effects. Thus O-3 episodes are less likely to be detrimental to P. trichocarpa x P. deltoides in the CO2 concentrations of the future.

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Published date: 2005
Keywords: CO2, O3, leaf growth, water relations, poplar, biomass accumulation

Identifiers

Local EPrints ID: 41079
URI: https://eprints.soton.ac.uk/id/eprint/41079
ISSN: 1445-4408
PURE UUID: 684b7264-1c84-4138-8422-2637a1a5132c
ORCID for Gail Taylor: ORCID iD orcid.org/0000-0001-8470-6390

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Date deposited: 14 Jul 2006
Last modified: 20 Jul 2019 01:10

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