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.
2011
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Iben M. Thomsen Venche Talgø Erling Fløistad Kari Ørstad Trude L. Slørstad Arne StensvandSammendrag
En alvorlig svampesygdom hærger buksbom i store dele af Europa. Sygdommen er også konstateret i Danmark og kan give store problemer i pyntegrønt bevoksninger af buksbom, samt få betydning for afsætning af klippegrønt.
Forfattere
Ricardo Holgado Christer MagnussonSammendrag
Cyst nematodes, Heterodera spp. are known world-wide as parasites of cereals and grasses. Norwegian surveys have revealed that nematodes belonging to the H. avenae complex occur throughout the country; our studies have combined morphology, protein variability (IEF), bio-tests and internal transcribed spacers (ITS3 and ITS5) for the identification of Heterodera populations. Our results showed some divergences between techniques in species identity of some of the studied populations H. avenae is the most common species followed by H. filipjevi (Holgado et al., 2009).. Several populations of H. filipjevi west did not reproduce in oat differentials. In this case both the morphology and protein patterns rather indicated these populations to belong to H. pratensis. In this study a population from Brekstad differed from all other populations in its morphology, and the protein pattern was close to H. mani. This population was collected from barley, and in the pathotype test it was virulent on several barley cultivars. Mathews, 1971reported that H. mani did not reproduce on cereals while (Cook, 1982) indicates that some barley cultivars can serve as hosts. Surprisingly the ITS studies indicated the Brekstad population to be close to H. avenae. This population is in many ways strikingly different from H. avenae, and this result may indicate a need to revise the present gene library of H. avenae. It also demonstrates the need for using several techniques in species identification. In our study the least degree of divergent results on nematode identity is between morphology and IEF.
Forfattere
Ricardo HolgadoSammendrag
Cyst nematodes, Heterodera spp. are known world-wide as parasites of cereals and grasses. Norwegian surveys have revealed that nematodes belonging to the H. avenae complex occur throughout the country; our studies have combined morphology, protein variability (IEF), bio-tests and internal transcribed spacers (ITS3 and ITS5) for the identification of Heterodera populations. Our results showed some divergences between techniques in species identity of some of the studied populations H. avenae is the most common species followed by H. filipjevi (Holgado et al., 2009).. Several populations of H. filipjevi west did not reproduce in oat differentials. In this case both the morphology and protein patterns rather indicated these populations to belong to H. pratensis. In this study a population from Brekstad differed from all other populations in its morphology, and the protein pattern was close to H. mani. This population was collected from barley, and in the pathotype test it was virulent on several barley cultivars. Mathews, 1971reported that H. mani did not reproduce on cereals while (Cook, 1982) indicates that some barley cultivars can serve as hosts. Surprisingly the ITS studies indicated the Brekstad population to be close to H. avenae. This population is in many ways strikingly different from H. avenae, and this result may indicate a need to revise the present gene library of H. avenae. It also demonstrates the need for using several techniques in species identification. In our study the least degree of divergent results on nematode identity is between morphology and IEF.
Redaktører
Tommy Staahl Gabrielsen Ivar PettersenSammendrag
Analyser av tilgjengelige data for tilpasninger i verdikjeden for matvarer i Norge bekrefter at norske forbrukere betaler en betydelig høyere pris for dagligvarene enn konsumentene i våre naboland. Én viktig årsak synes å være at kostnadsnivået for distribusjon av forbrukervarer generelt er høyere i Norge enn i våre naboland. Den andre viktige årsaken er jordbrukspolitikken som spesielt gjennom importvernet gir høye priser på norske jordbruksråvarer, og indirekte bidrar til høyere kostnadsnivå både i matindustrien og distribusjonen sammenlignet med våre naboland. Vi finner ingen holdepunkter for at en vesentlig del av prisforskjellene skyldes urimelige profittmarginer eller lav produktivitet i distribusjon og dagligvarehandel. Avlønningen til bøndene synes også å være lav. Artikkelsamlingens grove sammenligning av lønnsomhets- og produktivitetstall mellom land og sektorer, tyder ikke på at det er unormal høy profitt eller eventuell makt i dagligvaresektoren som forklarer en vesentlig del av norske forbrukeres merutlegg. Matkjedeutvalget har reist spørsmål av stor betydning for norsk verdiskaping og forbrukervelferd. Men viktige spørsmål av betydning for norske matpriser, har falt utenfor utredningen. Muligheter for å bedre dagens politikk, både landbruks- og matpolitikken og konkurransepolitikken, er i liten grad drøftet. Konklusjonene og anbefalingene representerer derfor en fare for ytterligere fragmentering og sektorisering av matvarepolitikken. Matkjedeutvalget har hatt begrensede ressurser, et avgrenset mandat, kort tid og sterk pågang fra sektorinteresser underveis. Denne artikkelsamlingen har et atskillig videre mandat, men, til gjengjeld, mindre tid og ressurser. Forfatterne er forskere, men det har ikke vært rom for egen forskning. Det gir grunn til forsiktighet – og to konklusjoner: Den dokumentasjonen som er tilgjengelig fra Matkjedeutvalgets arbeid, med tillegg av vår dokumentasjon, gir et utilstrekkelig grunnlag for ny politikk overfor norske verdikjeder for mat, og det er grunn til å arbeide videre både for bedre innsikt og effektivisering av virkemiddelbruken.
Sammendrag
On small dairy farms, high investment costs and lack of investment capital may delay the modernising of facilities. The aim of this study was to investigate the importance of economics of scale in building costs of barns compared to other sources of variation in costs. The study includes 44 farms with a mean herd size of 49.5 ± 15.1 cows, built between year 1999 and 2006 and with a mean total area in the barns of 896 ± 454 m2. Building cost data were obtained from farmers and merged with construction, mechanisation and layout data from the same barns. Construction costs decreased up to approximately 1250 m2 while mechanisation costs and total building costs decreased up to approximately 1000 m2. A further increase in building area had only limited effect on the building costs per m2. Models including explanatory variables showed that milking and service area was significantly more expensive than other areas. AMS-barns were all together not significantly more expensive than other barns, since the increased mechanisation cost is offset by a lower requirement for milking area. Farmers remodelling their barns were able to realise a modernised building for a certain herd size for a lower cost compared to a completely new building. The use of their own effort varied considerably between projects. In many cases, farmers would be able to find alternative income sources with a higher hourly rate than the value of their own effort suggested by the model.
Forfattere
Ragnhild Nærstad Arne Hermansen Vinh Hong Le Grete Lund Abdelhameed Elameen May Bente BrurbergSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Wood exhibits a highly anisotropic mechanical behavior due to its heterogeneous microscopic structure and composition. Its microstructure is organized in a strictly hierarchical manner from a length scale of some nanometers, where the elementary constituents cellulose, hemicelluloses, lignin, and extractives are found, up to a length scale of some millimeters, where growth rings composed of earlywood and latewood are observed. To resolve the microscale origin of the mechanical response of the macro-homogeneous but micro-heterogeneous material wood, micromechanical modeling techniques were applied. They allow for prediction of clear wood stiffness (Hofstetter et al. 2005,2007, Bader et al. 2010a,b) from microstructural characteristics. Fungal decay causes changes in the wood microstructure, expressed by decomposition or degradation of its components (Côté 1965, Schwarze 2007). Consequently, macroscopic mechanical properties are decreasing (see e.g. Wilcox 1978). Thus, in the same manner as for clear wood, consideration of alterations of wood in a micromechanical model allows predicting changes in the macroscopic mechanical properties. This contribution covers results from an extensive experimental program, where changes in chemophysical properties and corresponding changes in the mechanical behavior were investigated. For this purpose, pine (Pinus sylvestris) sapwood samples were measured in the reference condition, as well as degraded by brown rot (G. loeophyllum trabeum) or white rot (Trametes. versicolor). Stiffness properties of the unaffected and the degraded material were not only measured in uniaxial tension tests in the longitudinal direction, but also in the three principal material directions by means of ultrasonic testing. The experiments revealed transversal stiffness properties to be much more sensitive to degradation than longitudinal stiffness properties. This is due to the degradation of the polymer matrix between the cellulose fibers, which has a strong effect on the transversal stiffness. On the contrary, longitudinal stiffness is mainly governed by cellulose, which is more stable with respect to degradation by fungi. Consequently, transversal stiffness properties or ratios of normal stiffness tensor components may constitute suitable durability indicators. Subsequently, simple micromechanical models, as well as a multiscale micromechanical model for wood stiffness, were applied for verification of hypotheses on degradation mechanisms and model validation.
Forfattere
Trygve D. Kjellsen Igor A. Yakovlev Carl Gunnar Fossdal Richard StrimbeckSammendrag
Siberian spruce (Picea obovata) grows in the coldest forested environments on Earth, with average temperatures in midwinter months below -40 C and record lows below 60 C. Fully acclimated needles of this species survive immersion in liquid nitrogen at -196 C provided they are first cooled to an intermediate temperature of around -30 C. To investigate the role of dehydrins in extreme frost tolerance, we monitored frost tolerance, relative dehydrin concentration, and relative changes in dehydrin transcript levels in P. obovata needles over a full acclimation-deacclimation cycle.