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Heikki Smolander, Seppo Kellomäki, Pauline Oker-Blom

Typpipitoisuuden vaikutus männyn neulasten fotosynteesiin ja verson itsevarjostukseen.

Smolander H., Kellomäki S., Oker-Blom P. (1990). Typpipitoisuuden vaikutus männyn neulasten fotosynteesiin ja verson itsevarjostukseen. Silva Fennica vol. 24 no. 1 article id 5414. https://doi.org/10.14214/sf.a15566

English title: The effect of nitrogen concentration on needle photosynthesis and within shoot shading in Scots pine.

Abstract

A close relationship between photosynthetic capacity and nitrogen concentration of leaves is known to exist. In conifers, nitrogen also affects the pattern of mutual shading within a shoot, which is a basic unit used in studying photosynthesis of coniferous trees. These effects of needle nitrogen concentration on photosynthetic capacity and mutual shading of needles were analysed for Scots pine (Pinus sylvestris L.) shoots taken from five young stands growing on sites of different fertility. The effect of nitrogen concentration on needle photosynthesis was studied based on measurements of the photosynthetic radiation response of shoots from which two thirds of the needles were removed in order to eliminate the effect of within shading.

An increase of one percentage unit in nitrogen concentration of needles increased the photosynthetic capacity of needles by 25 mg CO2 dm-2h-1. The effect of nitrogen on within-shoot shading was quantified in terms of the silhouette area to total needle area ratio of a shoot (STAR), which determines the relative interception rate per unit of needle area on the shoot. Although nitrogen promoted needle growth, an increase in nitrogen concentration decreased the within-shoot shading. This effect resulted from a decrease in needle density on the shoot and an increased needle angle with increasing nitrogen content.

The PDF includes an abstract in Finnish.

Original keywords
mänty; kasvupaikkatekijät; ravinteisuus; verson rakenne; säteilyn sitomistehokkuus; fotosynteesi

English keywords
Pinus sylvestris; site factors; fertility; shoot structure; light interception efficiency; shading; photosynthesis

Published in 1990

Available at https://doi.org/10.14214/sf.a15566 | Download PDF

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