Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2004
Sammendrag
A home designed diffusion chamber was used during the isolation of fluoride from plant material. The chamber contained two beakers, one for the sample (milled plant material) and the other for the trapping solution (0.1M NaOH). Hexamethyldisiloxane (HMDS) in 3.5M perchloric acid was added into the sample beaker through a septum, after the chamber was closed.Fluoride in the sample reacts with HMDS and forms the volatile trimethylfluorosilane (TMFS), which is trapped and hydrolyzed to fluoride. The diffusion time was 2h and 20 samples were handled at the same time. The fluoride concentration was determined by a flow injection analysis (FIA) system using an ion selective electrode (about 50 samples/hour).The results by acid extraction were compared to the results obtained after an ashing/alkaline fusion. Both a certified sample of timothy grass (NIST 2695, high level) and more typical vegetation from forest were analyzed. For the timothy grass, the recovery increased from 48 to 84% when ashing/alkali fusion was used before the diffusion. However, higher recovery was not obtained by using ashing/alkaline fusion for the determination of fluoride in natural vegetation from forest. Acid extraction in combination with addition of HMDS was sufficient as pretreatment in these types of plant materials.The method was routinely used for the determination of fluoride both in research and forest monitoring.
Sammendrag
Konfidensiell.
Sammendrag
Sweet cherry trees sometimes suffer from dieback symptoms under Scandinavian growing conditions. Some combinations of cultivars and rootstocks are more susceptible to this than others. The graft union between a rootstock and a scion is a junction between two different tissues. Differences in tissue development in the union may provide a mechanistic explanation of inhibiting transport of water and nutritional substances and likely inhibit growth of the scion. In order to investigate the relationship between growth and the amount of functional xylem tissue of potted sweet cherry trees, an experiment was conducted during 2002-2003. One year old field budded and bench grafted (from green house) sweet cherry trees of the cultivars Van, Ulster and Lapins in all combinations of the three rootstocks Prunus avium seedling, Colt and Gisela 5 were grown in pots for two growing seasons. After shoot extension had terminated when trees were in full leaf the second year, the total growth of the different parts of the trees and the quantification of functional area using safranin staining were conducted. The total mass production (tree dry weight, the length of two year old wood and number of leaves) was significant larger in the budded trees. Similarly the trunk cross sectional area was significant larger 10 cm above and in the middle of the graft union, but not 10 cm below. The Colt trees were the most vigorous followed by the seedling and Gisela 5. Small differences between the different cultivars were registered. Xylem staining with aqueous safranin combined with quantitative image analysis showed that the rootstock stem had a higher proportion of stained tissue than the scion stem. Sections taken in the middle of the graft tissue and above showed that the proportion of stained tissue declined proportionally with the distance from the roots. The total area of stained stem xylem was larger for the two vigorous rootstocks compared to Gisela 5. Small differences were observed between cultivars and propagation methods.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
The anatomical defense responses in stems of Norway spruce (Picea abies) clones of different resistance to pathogenic fungi were characterized over time and distance from small mechanical wounds or wounds inoculated with the root rot fungus Heterobasidion annosum. Common responses for both treatments included division of ray parenchyma and other cells in the cambial zone, accumulation of phenolic inclusions in ray parenchyma cells, activation of phloem parenchyma (PP) cells, and formation of traumatic resin ducts (TDs) in the xylem. TD formation occurred synchronously from a tangential layer of cells, or symplasmic domain, within the zone of xylem mother cells. TD induction is triggered by a signal, which propagates a developmental wave in the axial direction at about 2.5cm per day. TDs are formed at least 30cm above single inoculations within 16–36days after inoculation. The size and number of TDs is attenuated further away from the inoculation site, indicating a dose-dependent activity leading to TD development. Compared to sterile wounding, fungal inoculation gave rise to more and larger TDs in all clones, and multiple rows of TDs in weak clones. Fungal inoculation also induced the formation of more new PP cells, increasing the number of PP cells in the phloem in the year of inoculation up to 100%. TD and PP cell formation was greater in susceptible compared to resistant clones and after fungal versus sterile inoculation. Potential mechanisms responsible for this variable response are discussed.
Forfattere
Jørn Kristian Lileng Erlend Ystrøm HaartveitSammendrag
Forest roads ensure access to standing timber and their standards may restrict the opportunity set for efficient logistical solutions. Traditionally, the objective of road investments has been maximisation of returns for the landowner.Investments in forest roads in Norway are subsidised by the Norwegian government. These subsidies should preferably be allocated to projects creating the best premises for efficient log supply. The total cost approach evaluates costs using a holistic perspective. In this paper we use this approach to evaluate the profitability of investments in forest roads so that the total costs for log supply to the industry are minimised.The distribution of standing timber in the catchment area of the forest road is also taken into account. The results show that the sum of costs for road construction, harvesting and forwarding account for more than 99% of the total costs, compared to less than 1% for the sum of log hauling costs. Differentiation of forest road standards is more appropriate in situations where the volume of standing timber decreases in remote areas of the forest road network.
Forfattere
Tor Håkon SivertsenSammendrag
The main idea of this paper is taking a step towards clarification of the scope of the concept of continuity of continuum mechanics, when this concept ought to be used. Mathematics is in an auxiliary way defined as a formal extension of mans ability to compare, aggregate and divide aggregates of objects in the physical world. Then the formal mathematical concept of continuity of the real line is discussed, and the conclusion is that according to the definition of mathematics used, there exist no continuous physical medium what so ever. Then the concepts of continuity and discontinuity have no meaning for any physical medium beyond the possibility of making measurements of defined parameters. Literature: Brown, David, 1997, An Introduction to Object-Oriented Analysis, John Wiley and Sons. INC, New York, 700pp Cohen, P.J., 1963, The Independence of the Continuum-Hypothesis, Proc. Nat. Acad. Sci. U.S.A. 50, 1143-1148 Devlin, Keith ,1993, The Joy of Sets, Fundamentals of Contemporary Set Theory, Springer-Verlag New York Berlin, 192 pp Gödel, K., 1940, The Consistency of the Continuum-Hypothesis, Princton, NJ: Princton University Press Rudin, W., 1964, Principles of Mathematical Analysis, McGRAW-HILL BOOK COMPANY, New York San Fransisco Toronto London, 270 pp. Sivertsen, T.H. ,2004, Discussing scientific methods and the quality of meteorological data, part of a report to be published by COST 718 ACTION( `Meteorological Applications for Agriculture"), 19 p ( In press)
Forfattere
Tor Håkon SivertsenSammendrag
The idea of this paper is discussing the concept of `turbulence" and some ways of describing and documenting this phenomenon or this group of phenomena by using a slightly different interpretation of the hypothetico-deductive principle than usual. Then the concept of `turbulence" connected to the Navier-Stokes system of equations is discussed. One main problem is finding relevant parameters of fluid phenomena on smaller temporal and spatial scales than contained in a model used operationally or derived from a system for making measurements of the meteorological parameters. These phenomena on smaller scales may consist of eddies (turbulence) as well as internal waves. Some formal aspects of the Navier-Stokes system of equations are then discussed by looking at a stationary system. The discussion of this paper is concluded by proposing some features of a classification system of some of the parameters used in fluid dynamics.
Forfattere
Torjus Bolkesjø Hans Fredrik HoenSammendrag
Det er ikke registrert sammendrag
Sammendrag
Ved Skogforsks laboratorium kan vi ved hjelp av DNA analyser finne ut om et plantefelt er av nordisk eller mellomeuropeisk opprinnelse. Vi har brukt teknikken til å sammenlikne avkom fra norske og mellomeuropeiske mortrær fra samme område. Avkom fra mellomeuropeiske mortrær i Norge oppfører seg mer som norske planter enn som planter fra mortreets opprinnelsessted.