carotenoids; irradiance; net photosynthetic rate; photosystem 2; Picea abies

The acclimative depression of capacity of light utilization in PS2 photochemical reactions can develop already after three months of the cultivation of the Norway spruces under elevated concentrations of CO2 in glass domes with adjustable windows.To examine the role that duration of EC plays in acclimation response, we determined pigment contents, rate of photosynthesis and the individual parameters of chlorophyll a fluorescence for sun and shade needles after three seasons of EC exposure.On the basis of these parameters we found different responses of shaded and exposed needles to EC. Whereas the shaded needles still profited from the EC and revealed stimulated electron transport, for the exposed needles the stimulation of both electronOn the basis of these parameters we found different responses of shaded and exposed needles to EC. Whereas the shaded needles still profited from the EC and revealed stimulated electron transport, for the exposed needles the stimulation of both electron

The acclimative depression of capacity of light utilization in PS2 photochemical reactions can develop already after three months of the cultivation of the Norway spruces under elevated concentrations of CO2 in glass domes with adjustable windows.To examine the role that duration of EC plays in acclimation response, we determined pigment contents, rate of photosynthesis and the individual parameters of chlorophyll a fluorescence for sun and shade needles after three seasons of EC exposure.On the basis of these parameters we found different responses of shaded and exposed needles to EC. Whereas the shaded needles still profited from the EC and revealed stimulated electron transport, for the exposed needles the stimulation of both electrontransport activity and irradiance saturated rate of CO2 assimilation (PNmax) under EC already disappeared.