Photosynthetic Characteristics of Sun and Shade Leaves in the Canopy of Arbutus unedo L. Trees Exposed to In Situ Long-Term Elevated CO2 |
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Authors: | Barták M Raschi A Tognetti R |
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Institution: | (1) Department of Plant Physiology and Anatomy, Masaryk University, Kotlářská 2, 61137 Brno, Czech Republic;(2) Institute of Environmental Analysis and Remote Sensing for Agriculture, Piazzale delle Cascine 18, 50144 Firenze, Italy;(3) Department of Botany, Trinity College, University of Dublin, Dublin 2, Ireland |
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Abstract: | Photosynthetic parameters were studied in Arbutus unedo L. trees growing at either ambient (AC) or elevated EC (mean 465 μmol mol-1) CO2 concentration near a natural CO2 vent in Orciatico, Italy Diurnal courses of net photosynthetic rate (P
N), ratio of variable to maximum chlorophyll fluorescence (Fv/Fm), and quantum yield of electron transport through photosystem 2 (Φ2) were measured on sun and shade leaves. The contents of N, C, Ca, K, P, and chlorophyll (Chl) and specific leaf area (SLA)
in these leaf categories were also determined. A morning peak and midday depression of P
N were found for both AC and EC sun leaves. Long-term EC caused little or no down-acclimation of P
N in sum leaves. The estimate of total daily CO2 uptake was lower in AC leaves than in EC leaves. In shade leaves, it reached up to 70 % of the value of sun leaves. The Fv/Fm ratio showed decreasing trend in the morning, reached a minimum at midday (90 % of dawn value), and then increased in the
afternoon. The EC had no effect on Fv/Fm either in sun or shade leaves. Plants grown near the CO2 spring had lower Chl content, higher SLA, and higher Ca and K contents than plants grown under AC.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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