, 37:433

Response of Photosynthesis to Radiation and Intercellular CO2 Concentration in Sun and Shade Shoots of Norway Spruce

  • M. Šprtová
  • M.V. Marek

DOI: 10.1023/A:1007111911415

Cite this article as:
Šprtová, M. & Marek, M. Photosynthetica (1999) 37: 433. doi:10.1023/A:1007111911415


Functional differentiation of assimilation activity of sun versus shade foliage was analysed in a Norway spruce monoculture stand (age 15 years). The investigated stand density (leaf area index 8.6) and crown structure led to variation in the photosynthetically active photon flux density (PPFD) within the crowns of the sampled trees. At the saturating PPFD, the maximum rate of CO2 uptake (PNmax) of exposed shoots (E-shoots) was 1.7 times that of the shaded shoots (S-shoots). The apparent quantum yield (α) of E-shoots was 0.9 times that of the S-shoots. A lower ability to use excess energy at high PPFD in photosynthesis was observed in the S-layer. The CO2- and PPFD-saturated rate of CO2 uptake (PNsat) of the E-shoots was 1.12 times and the carboxylation efficiency (τ) 1.6 times that of the S-shoots. The CO2-saturated rate of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) carboxylation (VCmax) and of actual electron transport (Jamax) in the S-needles amounted to 89 and 95 % of VCmax and Jamax in the E-needles. Thus, in addition to the irradiation conditions and thus limitation by low Ja, the important limitation of photosynthesis in shade needles is due to carboxylation. This limitation of photosynthesis is accompanied by lower stomatal conductance.

apparent quantum yield carboxylation efficiency compensation irradiance dark respiration electron transport rate intercellular CO2 concentration needle area/mass ratio Picea abies shade/sun foliage stomatal conductance 

Copyright information

© Kluwer Academic Publishers 1999

Authors and Affiliations

  • M. Šprtová
    • 1
  • M.V. Marek
    • 1
  1. 1.Laboratory of Ecological Physiology of Forest Trees, Institute of Landscape EcologyAcademy of Sciences of the Czech RepublicBrnoCzech Republic

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