Journal Article

Variability of the photosynthetic characteristics of mature needles within the crown of a 25-year-old <i>Pinus pinaster</i>

Annabel Porté and Denis Loustau

in Tree Physiology

Volume 18, issue 4, pages 223-232
Published in print April 1998 | ISSN: 0829-318X
Published online April 1998 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/18.4.223
Variability of the photosynthetic characteristics of mature needles within the crown of a 25-year-old Pinus pinaster

More Like This

Show all results sharing this subject:

  • Plant Sciences and Forestry

GO

Show Summary Details

Preview

Photosynthetic characteristics of 1- and 2-year-old needles were determined in excised shoots of maritime pine (Pinus pinaster Ait.) with an open gas exchange system. We used the nonlinear least mean squares method to derive values for quantum yield of electron transport (α), maximum carboxylation velocity (Vcmax), and maximum electron transport rate (Jmax), from photosynthetic response curves to light and CO2. Crown height had no significant effect on any of the parameters; however, Vcmax and Jmax, as well as α were 43, 26 and 35% higher, respectively, in 1-year-old needles than in 2-year-old needles. The main effect of irradiance on needles was a small decline in leaf concentrations of nitrogen and phosphorus from the top to the bottom of the canopy. Only Jmax demonstrated a linear relationship with both nitrogen content (R2 = 0.42) and irradiance at the shoot level. Because needle age accounted for most of the variability in photosynthesis, we incorporated needle age into the photosynthesis model of Farquhar et al. (1980). The modified model underestimated the daily assimilation rate of 1-year-old needles in the field, especially when assimilation rates were high.

Keywords: maritime pine; model; needle age; nitrogen; phosphorus; photosynthesis

Journal Article.  0 words. 

Subjects: Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.