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Please use this identifier to cite or link to this item: http://dspace.utalca.cl/handle/1950/4064

Title: Gas exchange acclimation to elevated CO2 in upper-sunlit and lower-shaded canopy leaves in relation to nitrogen acquisition and partitioning in wheat grown in field chambers
Authors: Del Pozo Lira, Alejandro
Perez, P.
Gutierrez, D.
Alonso, A.
Morcuende, R.
Martinez-Carrasco, R.
Keywords: Triticum aestivum L.; Acclimation; Chlorophyll; Elevated CO2; Nitrogen; Photosynthesis; Rubisco activity; Stomatal conductance; Transpiration
Issue Date: 2007
Publisher: Elsevier B.V.
Citation: Environmental and Experimental Botany 59 (3): 371-380
Abstract: Growth at elevated CO2 often decreases photosynthetic capacity (acclimation) and leaf N concentrations. Lower-shaded canopy leaves may undergo both CO2 and shade acclimation. The relationship of acclimatory responses of flag and lower-shaded canopy leaves of wheat (Triticum aestivum L.) to the N content, and possible factors affecting N gain and distribution within the plant were investigated in a wheat crop growing in field chambers set at ambient (360 μmol mol−1) and elevated (700 μmol mol−1) CO2, and with two amounts of N fertilizer (none and 70 kg ha−1 applied on 30 April). Photosynthesis, stomatal conductance and transpiration at a common measurement CO2, chlorophyll and Rubisco levels of upper-sunlit (flag) and lower-shaded canopy leaves were significantly lower in elevated relative to ambient CO2-grown plants. Both whole shoot N and leaf N per unit area decreased at elevated CO2, and leaf N declined with canopy position. Acclimatory responses to elevated CO2 were enhanced in N-deficient plants. With N supply, the acclimatory responses were less pronounced in lower canopy leaves relative to the flag leaf. Additional N did not increase the fraction of shoot N allocated to the flag and penultimate leaves. The decrease in photosynthetic capacity in both upper-sunlit and lower-shaded leaves in elevated CO2 was associated with a decrease in N contents in above-ground organs and with lower N partitioning to leaves. A single relationship of N per unit leaf area to the transpiration rate accounted for a significant fraction of the variation among sun-lit and shaded leaves, growth CO2 level and N supply. We conclude that reduced stomatal conductance and transpiration can decrease plant N, leading to acclimation to CO2 enrichment.
Description: del Pozo, A. Universidad de Talca, Facultad de Ciencias Agrarias, Casilla 747, Talca, Chile. E-mail adelpozo@utalca.cl.
URI: http://dspace.utalca.cl/handle/1950/4064
ISSN: 0098-8472
Appears in Collections:Artículos en publicaciones ISI - Universidad de Talca

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