Effect of Elevated Carbon Dioxide Concentration on Carbon Assimilation under Fluctuating Light
- Petra Holišováab,
- Martina Zitováa,
- Karel Klema and
- Otmar Urban *a
Natural fluctuations in light intensity may significantly affect the amount of CO2 assimilated by plants and ecosystems. Little is known, however, about the interactive effect of dynamic light conditions and atmospheric CO2 concentrations. The hypothesis that elevated CO2 concentration (EC; 700 μmol CO2 mol−1) increases photosynthetic efficiency in dynamic light environments as compared to ambient CO2 concentration (AC; 385 μmol CO2 mol−1) was tested. Sun leaves of European beech (Fagus sylvatica L.) and current-year shoots of Norway spruce [Picea abies (L). Karst.] were exposed to five dynamic light regimes (LRs) occurring within forest canopies due to variable cloud cover or self-shading of leaves and to a steady-state LR. The LRs differed in the time course of incident irradiance, whereas the overall duration (600 s) and total amount of radiation (35.88 mmol photons m−2) were the same in all LRs. The EC treatment enhanced the amount of CO2 assimilated under all LRs tested. While the stimulation was only 37 to 50% in beech, it was 52 to 85% in spruce. The hypothesis that photosynthetic efficiency is stimulated by EC was confirmed in LRs when the leaves were pre-exposed to low light intensity and photosynthetic induction was required. By contrast, only a minor effect of EC treatment was found on the rate of induction loss and postillumination CO2 fixation in both species studied.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2012. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.