Trees

, Volume 23, Issue 6, pp 1149–1161

Contribution of diffusional and non-diffusional limitations to midday depression of photosynthesis in Arbutus unedo L.

  • Giacomo Grassi
  • Francesco Ripullone
  • Marco Borghetti
  • Sabrina Raddi
  • Federico Magnani
Original Paper

DOI: 10.1007/s00468-009-0355-7

Cite this article as:
Grassi, G., Ripullone, F., Borghetti, M. et al. Trees (2009) 23: 1149. doi:10.1007/s00468-009-0355-7

Abstract

It is still unknown whether the midday depression of photosynthesis under severe water stress, frequently observed in plants growing in a Mediterranean-type climate, is primarily a consequence of diffusional or non-diffusional limitations. We carried out combined measurements of gas exchanges and chlorophyll fluorescence in field-grown Arbutus unedo L. trees during late spring and mid summer, and a quantitative limitation analysis was performed to distinguish between the different limitations to photosynthesis, i.e., diffusional [DL = stomatal (SL) + mesophyll (MCL)] and non-diffusional (carboxylation capacity and electron transport, BL) limitations. Light-saturated assimilation at ambient CO2 (Amax), stomatal conductance to water vapour (gsw) and maximum carboxylation rate (VcmaxCi) showed a marked midday depression during both periods. The total limitations tended to increase during the day and were remarkably similar in June and July (50 and 48%, respectively); on a daily basis, DL was similar to BL (about 23%) in June; whereas, in July the former was predominant (38 and 4%, respectively). We concluded that the midday depression in photosynthesis was largely caused by diffusional limitations, with non-diffusional limitations playing a smaller role. Although stomatal closure was the main diffusional limitation, the decline in mesophyll conductance was not negligible during the hottest and driest period.

Keywords

Mediterranean forestMesophyll conductanceQuantitative limitation analysisStomatal conductanceWater stress

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Giacomo Grassi
    • 1
  • Francesco Ripullone
    • 2
  • Marco Borghetti
    • 2
  • Sabrina Raddi
    • 3
  • Federico Magnani
    • 4
  1. 1.Climate Change Unit TP 050, Institute for Environment and SustainabilityEuropean Commission, Joint Research CentreIspraItaly
  2. 2.Department of Crop, Forest and Environmental SciencesUniversity of BasilicataPotenzaItaly
  3. 3.Department of Forest and Environmental SciencesUniversity of FirenzeFlorenceItaly
  4. 4.Department of Fruit and TreesUniversity of BolognaBolognaItaly