Diurnal changes in photosynthetic parameters of Poulus tremuloides, modulated by elevated concentrations of CO2 and/or O3 and daily climatic variation

Katre Kets; Joseph N.T. Darbah; Anu Sober; Johanna Riikonen; Jaak Sober; David F. Karnosky

doi:10.1016/j.envpol.2009.09.001

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Diurnal changes in photosynthetic parameters of Poulus tremuloides, modulated by elevated concentrations of CO₂ and/or O₃ and daily climatic variation

Formally Refereed

Authors:

Katre Kets, Joseph N.T. Darbah, Anu Sober, Johanna Riikonen, Jaak Sober, David F. Karnosky

Year:

2010

Type:

Scientific Journal

Station:

Northern Research Station

DOI:

https://doi.org/10.1016/j.envpol.2009.09.001

Source:

Environmental Pollution. 158(4): 1000-1007.

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Abstract

The diurnal changes in light-saturated photosynthesis (Pn) under elevated CO₂ and/or O₃ in relation to stomatal conductance (g_s), water potential, intercellular [CO₂], leaf temperature and vapour-pressure difference between leaf and air (VPD_L) were studied at the Aspen FACE site. Two aspen (Populus tremuloides Michx.) clones differing in their sensitivity to ozone were measured. The depression in Pn was found after 10:00 h. The midday decline in Pn corresponded with both decreased g_s and decreased Rubisco carboxylation efficiency, Vc_max. As a result of increasing VPD_L, g_s decreased. Elevated [CO₂] resulted in more pronounced midday decline in Pn compared to ambient concentrations. Moreover, this decline was more pronounced under combined treatment compared to elevated CO₂ treatment. The positive impact of CO₂ on Pn was relatively more pronounced in days with environmental stress but relatively less pronounced during midday depression. The negative impact of ozone tended to decrease in both cases.

Keywords

Photosynthesis, Stomatal conductance, Vapour-pressure difference, Environmental stress, CO2/O3

Citation

Kets, Katre; Darbah, Joseph N.T.; Sober, Anu; Riikonen, Johanna; Sober, Jaak; Karnosky, David F. 2010. Diurnal changes in photosynthetic parameters of Poulus tremuloides, modulated by elevated concentrations of CO₂ and/orO₃ and daily climatic variation. Environmental Pollution. 158(4): 1000-1007.