title: Early and late adjustments of the photosynthetic traits and stomatal density in Quercus ilex L. grown in an ozone-enriched environment.
abstract: Quercus ilex L. seedlings were exposed in open-top chambers for one growing season to three levels of ozone (O3 ): charcoal filtered air, non-filtered air supplemented with +30% or +74% ambient air O3 . Key functional parameters related to photosynthetic performance and stomatal density were measured to evaluate the response mechanisms of Q. ilex to chronic O3 exposure, clarifying how ecophysiological traits are modulated during the season in an ozone-enriched environment. Dark respiration showed an early response to O3 exposure, increasing approximately 45% relative to charcoal-filtered air in both O3 enriched treatments. However, at the end of the growing season, maximum rate of assimilation (Amax ) and stomatal conductance (gs ) showed a decline (-13% and -36%, for Amax and gs , respectively) only in plants under higher O3 levels. Photosystem I functionality supported the capacity of Q. ilex to cope with oxidative stress by adjusting the energy flow partitioning inside the photosystems. The response to O3 was also characterised by increased stomatal density in both O3 enriched treatments relative to controls. Our results suggest that in order to improve the reliability of metrics for O3 risk assessment, the seasonal changes in the response of gs and photosynthetic machinery to O3 stress should be considered.
authors: Department of Environmental Biology, Sapienza University of Rome, Rome, Italy.
authors: L
authors: L
authors: Fusaro
authors: Department of Mathematics and Physics, Catholic University, Brescia, Italy.
authors: G
authors: G
authors: Gerosa
authors: Department of Environmental Biology, Sapienza University of Rome, Rome, Italy.
authors: E
authors: E
authors: Salvatori
authors: Department of Mathematics and Physics, Catholic University, Brescia, Italy.
authors: R
authors: R
authors: Marzuoli
authors: Department of Agricultural and Environmental Sciences, University of Milan, Milan, Italy.
authors: R
authors: R
authors: Monga
authors: Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), University of Tuscia, Viterbo, Italy.
authors: E
authors: E
authors: Kuzminsky
authors: Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), University of Tuscia, Viterbo, Italy.
authors: C
authors: C
authors: Angelaccio
authors: Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), University of Tuscia, Viterbo, Italy.
authors: D
authors: D
authors: Quarato
authors: Council for Agricultural Research and Economics, Research Centre for the Soil-Plant System, Rome, Italy.
authors: S
authors: S
authors: Fares
mesh_terms: D004777:Environment; D018384:Oxidative Stress; D010126:Ozone / Q000009:adverse effects*; D010788:Photosynthesis / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology; D018526:Plant Transpiration / Q000187:drug effects*; D029963:Quercus / Q000187:drug effects / Q000502:physiology*; D015203:Reproducibility of Results; D012621:Seasons; D036226:Seedlings / Q000187:drug effects / Q000502:physiology
chemical_list: D010126:Ozone
keywords: Holm oak; Photosystem I; leaf dark respiration; open-top chambers; ozone; photosynthesis; stomatal conductance; stomatal density