Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
1998
Authors
M.J. Latkowska Harald Kvaalen M. AppelgrenAbstract
No abstract has been registered
Authors
Bengt Ehnström Erkki Annila Øystein Austarå Susanne Harding Jon Gunnar OttossonAbstract
No abstract has been registered
Authors
Oddvar Skre Frans-Emil Wielgolaski Bjørn MoeAbstract
No abstract has been registered
Authors
Tore SkrøppaAbstract
No abstract has been registered
Authors
Tore SkrøppaAbstract
No abstract has been registered
Authors
Espen Lydersen Valter Angell Odd Eilertsen Thorbjørn Larssen Jan Mulder I.P. Muniz Hans Martin SeipAbstract
No abstract has been registered
Authors
Vincent R. Franceschi Trygve Krekling Alan A. Berryman Erik ChristiansenAbstract
The bark anatomy of Norway spruce clones that were resistant or susceptible to Ceratocystis polonica, a bark beetle vectored fungal pathogen, was compared. The major difference concerned the axial parenchyma cells, called polyphenolic parenchyma (PP cells) because of their vacuolar deposits. The phenolic nature of the deposits was indicated by autofluorescence under blue light, and immunocytochemical studies demonstrating PP cells are enriched in phenylalanine ammonia lyase (EC 4.3.1.5), a key enzyme in phenolic synthesis. Susceptible clone PP cells occurred as single rows filled with dense deposits. The resistant clone had 40% more PP cells, which occurred in rows two cells thick with individual cells also scattered among the sieve cells, and had lighter deposits. Trees inoculated with fungus were analyzed but a distinct fungal response could not be separated from the general wound response. In the resistant clone, phenolic bodies were reduced in size and density or disappeared completely 12 day after wounding, and PP cell size increased. The susceptible clone phenolics and cell size changed only slightly. These data show that PP cells are active in synthesis, storage, and modification of phenolics in response to wounding, providing a primary site of constitutive and inducible defenses.
Authors
Sondre Skatter Bohumil KuceraAbstract
A new theory is presented on the cause of the prevalent directions of the spiral grain patterns found in conifers. The hypothesis is based upon the assumption that spiral grain has a function, i.e. that it represents a growth strategy to ensure survival of the trees. The mechanical function of the tree trunk is placed in focus, that is the ability of the trees to withstand external mechanical loads, mainly from wind. Spiral grain is an optimized growth feature when the trees are exposed to combined bending and torsion. Torsion occurs when the crown is asymmetric in the plane perpendicular to the wind direction. Systematic crown asymmetry, with heavier crowns on the south side, was confirmed by measuring the crown projections on 253 sparsely grown pines; 76.7% of the trees had longer branches on the south than on the north side, and the average length difference was 40.8 cm. By studying wind maps it was seen that most of the coniferous forests have prevailing westerly winds, which, when combined with the crown asymmetry, leads to a prevailing torque. Right-handed spiral grain in the outermost layers of mature trees is proposed to be a strategy to withstand this torque, i.e. to avoid stem breakage
Authors
Anne Sverdrup-Thygeson Fred MidtgaardAbstract
No abstract has been registered
Authors
E. Hellström M. Palo Birger SolbergAbstract
No abstract has been registered