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.
1986
Forfattere
Kåre Olav VennSammendrag
No abstract has been registered
Forfattere
A.K. Hellum G.H. LinfieldSammendrag
No abstract has been registered
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Halvor SolheimSammendrag
No abstract has been registered
Forfattere
Knut SolbraaSammendrag
No abstract has been registered
Forfattere
Stein MagnesenSammendrag
No abstract has been registered
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Tron Eid Jo Heringstad Sveinung NerstenSammendrag
No abstract has been registered
Forfattere
Kristian Bjor Finn H. Brække Magne HuseSammendrag
No abstract has been registered
Forfattere
Erik Christiansen Anders EricssonSammendrag
Coniferous trees resist invasion of their phloem and xylem by microorganisms through an induced defence reaction; resin-filled reaction zones are formed around the infections to stop the intrusion. The efficacy of the reaction is supposedly dependent on an ample supply of carbohydrates. Two hypotheses were formulated: (i) phloem starch reserves are consumed by the defence reaction; (ii) trees low in phloem starch are vulnerable to infection. To test the hypotheses, stem sections of Picea abies trees were mass inoculated with a pathogenic blue-stain fungus, Ceratoscystis polonica, associated with the spruce bark beetle Ips typographus. Stem starch concentration was manipulated through girdling. Mass inoculation lead to a significant decrease in phloem starch concentration. Starch reserves of single trees were not correlated to their resistance to infection. Translocation capacity of the phloem is suggested critical for the defence reaction.
Forfattere
K. KuuselaSammendrag
No abstract has been registered
Forfattere
Bjørn LangerudSammendrag
The method presented was based on a very simple approach of the forces operating in the pores of porous media. The standardized time (tv) needed to infiltrate a given volume of a liquid into a porous medium in a defined state was throught to be an integrated measure of pore geometry and continuity. The state of the pore system was defined by external suction (S) and medium porosity characterized by the parameters k1 and k2 in the equation tv=k1k2 S-0.5. The method theory was not rejected by experiments with glass beads and selected peat based growth media. The method ranked the media with respect to the probability for satisfactory gas exchange in the order of peat, peat and 26% perlite, peat and 34% perlite, and peat and 44% mineral wool. This ranking was achieved 95 days after the media were filled in containers and exposed to a daily watering procedure. Before this time, the ranking of the media was slightly different, if at all possible. Five days after the containers were filled, only peat and 44% mineral wood was significantly different from the other media. Judged by the standardized time method, the probability for satisfactory gas exchange decreased significantly during the 95 days experiment. This aggravation was supported by measurements of the volume fraction of pores filled with gas. The changes with time were least marked in the medium containing mineral wool.