Articles by Virpi Palomäki

The effects of realistically elevated O₃ and CO₂ concentrations on the needle ultrastructure and photosynthesis of ca. 20-year-old Scots pine (Pinus sylvestris L.) saplings were studied during one growth period in open-top field chambers situated on a natural pine heath at Mekrijärvi, in eastern Finland. The experiment included six different treatments: chamberless control, filtered air, ambient air and elevated O₃, CO₂ and O₃ + CO₂. Significant increases in the size of chloroplast and starch grains were recorded in the current-year needles of the saplings exposed to elevated CO₂ These responses were especially clear in the saplings exposed to elevated O₃ + CO₂ concentrations. These treatments also delayed the winter hardening process in cells. In the shoots treated with O₃, CO₂ and combined O₃ + CO₂ the P_max was decreased on average by 50% (ambient CO₂) and 40% (700 ppm CO₂). Photosynthetic efficiency was decreased by 60% in all the treated shoots measured under ambient condition and by 30% in the CO₂ and O₃ + CO₂ treated shoots under 700 ppm. The effect of all the treatments on photosynthesis was depressive which was probably related to evident accumulation of starch in the chloroplasts of the pines treated with CO₂ and combined O₃ + CO₂. But in O₃ treated pines, which did not accumulate starch in comparison to pines subjected to ambient air conditions, some injuries may be already present in the photosynthetic machinery.

• Palomäki, E-mail: vp@mm.unknown
• Holopainen, E-mail: th@mm.unknown
• Kellomäki, E-mail: sk@mm.unknown
• Laitinen, E-mail: kl@mm.unknown

• Palomäki, University of Kuopio, Department of Ecology and Environmental Science, P.O.Box 1627, FIN-70211 Kuopio, Finland E-mail: virpi.palomaki@uku.fi
• Hassinen, Mekrijärvi Research Station, FIN-82900 Ilomantsi, Finland E-mail: ah@nn.fi
• Lemettinen, Mekrijärvi Research Station, FIN-82900 Ilomantsi, Finland E-mail: ml@nn.fi
• Oksanen, University of Kuopio, Department of Ecology and Environmental Science, P.O.Box 1627, FIN-70211 Kuopio, Finland E-mail: to@nn.fi
• Helmisaari, Finnish Forest Research Institute, Department of Forest Ecology, P.O.Box 18, FIN-01301 Vantaa, Finland E-mail: hsh@nn.fi
• Holopainen, Agricultural Research Centre, FIN-31600 Jokioinen, Finland E-mail: jh@nn.fi
• Kellomäki, University of Joensuu, Faculty of Forestry, P.O.Box 111, FIN-80101 Joensuu, Finland E-mail: sk@nn.fi
• Holopainen, University of Kuopio, Department of Ecology and Environmental Science, P.O.Box 1627, FIN-70211 Kuopio, Finland E-mail: th@nn.fi