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.
2006
Forfattere
Svein Ole Borgen Per Ove RøkholtSammendrag
Det er ikke registrert sammendrag
Sammendrag
Hydrology in the northern hemisphere is greatly affected by permafrost and seasonally frozen soils. In areas of permafrost only the top layer of the ground, as well as various thawed structures in the permafrost layer, are active from a hydrological point of view. Water supply is a big challenge in areas with permafrost. Changes in mechanical properties caused by changes in permafrost have also received much attention. Frozen ground near the surface will influence the distribution of melt-water and rain to run-off or infiltration. Changes in englacier and subglacier hydrology are important indicators of global warming. In this chapter examples of different geophysical methods applicable for charcterising flow and transport in cold regions are described. Case-studies carried out in Svalbard, Russia, Norway and Switzerland are presented. The examples relate to: leakages below frozen dams using electromagnetic (EM) soundings; EM soundings of saline permafrost and anomalous polarization; saltwater injection into permafrost zone; infiltration and solute transport in a partially frozen soil monitored by surface tomographic electrical resistivity techniques; drainage conditions beneath a glacier. The case studies presented (as well as examples from the literature) illustrate that most common geophysical methods are applicable in cold regions but may face problems with grounding or calibration of measurements with respect to hydrological meaningful properties such as water contents, etc. Temperature and phase change affect geophysical properties, and in combination with changes in solute concentration or changes in water content, the interpretation is made more complicated. Combining different geophysical and conventional methods may help to solve this problem.
Forfattere
Arne Stensvand Venche Talgø Gunn Mari Strømeng Heidi Udnes Aamot Jorunn Børve Arild Sletten Sonja KlemsdalSammendrag
Denne artikkelen gir ein oversikt over funn av jordbærsvartflekk (Colletotrichum acutatum) i Noreg og funn av C. acutatum på andre vertplanter. Innleiande studiar av genetisk variasjon mellom isolat av C. acutatum frå ulike vertplanter vert også skildra.
Sammendrag
Denne artikkelen (abstrakt) rapporterer frå funn av Colletotrichum acutatum på knoppar av søt- og surkirsebær og eple.
Forfattere
Heidi Udnes Aamot Gunn Mari Strømeng Venche Talgø Jorunn Børve Sonja Klemsdal Arne StensvandSammendrag
Denne artikkelen (abstrakt) skildrar identifikasjon av C. acutatum og genetisk variasjon mellom isolat frå jordbær og andre vertplanter.
Sammendrag
Søtkirsebærknoppar på bukettgreiner og skot vart undersøkt for smitte av Colletotrichum acutatum før knoppsprett i 4 sesongar. Både knoppar frå greiner som var smitta med C. acutatum året før og naturleg infiserte knoppar vart undersøkt. Soppen sporulerte på knoppane med små oransje hornliknande strukturar. Frå naturleg infiserte greiner var det frå 2 til 80% knoppar med sporulering på bukettgreiner og 0 til 53% på knoppar frå skot. Tilsvarande på knoppar frå greiner smitta året før var 38 til 79% på bukettgreiner og 4 til 45% på skot. På bukettgreinene som har både generative og vegetative knoppar var det mest sporulering på dei generative. Slike infeksjonar på knoppar er truleg ei viktig kjelde til smitte av C. acutatum om våren.
Sammendrag
The difficulty in sub-culturing biotrophic fungi complicates etiological studies related to the associated plant diseases. By employing species-specific ITS sequence stretches, we used real-time PCR to investigate the spatial colonization profiles of T. areolata and a co-existing Phomopsis species in seedlings and saplings of Norway spruce showing bark necrosis. There was a strong gradient in the colonization level of T. areolata DNA along the lesion length, with the highest DNA amount levels being recorded in the area with dark brown phloem. The separate analysis of bark and wood tissues indicated that the initial spread of the rust to healthy tissues neighbouring the infection site presumably takes place in the bark. A Phomopsis species co-existing together with T. areolata in several cases showed very high DNA levels in the upper part of the lesion outside the brown phloem area, and even in the visually healthy proximal tissues above the lesions. This indicates that this ascomycete has a latent stage during early colonization of Norway spruce shoots. This mode of infection most probably explains the successful co-existence of Phomopsis with a biotrophic rust, as their mutual interest would be to avoid triggering host cell death.
Forfattere
Ricardo Holgado Janet Rowe Stig Andersson Christer MagnussonSammendrag
Cereal cyst nematodes, Heterodera spp., are recognised throughout the world as economically important parasites of cereals. The virulence status on cereal cultivars differs between and within different species of the H. avenae-complex, and several pathotypes occur among them. A survey during 1995-2005 in Norway revealed that Heterodera spp. is common throughout the country. Studies in Norway have recorded H. filipjevi and also additional and possibly new species. A number of cereal cyst nematode populations from various regions of Norway, Sweden and the British Isles have been analysed using molecular, morphological and host range studies during the last three years. Fifteen populations, of the initial group of forty, are being studied more closely. Studies using isoelectric focusing and silver staining have detected divergent populations of H. avenae. The Swedish populations Ringsåsen seemed to be identical to a population found in Australia and the Swedish population Halland shows a protein profile separate from H. avenae. DNA studies are being used to determine if these populations are new species. An assortment of cereal cultivars, based on an international collection used for resistance testing, differentiates three groups, H. avenae (pathotypes Ha 11 and Ha 12), H. filipjevi (pathotype "West"), and a population from central Norway close to H. pratensis. Knowledge of the diversity of cereal cyst nematodes and their multiplication rates on their cereal hosts is of fundamental importance for efficient control strategies involving resistant cultivars. In Norway, management based on these parameters are in operation and have increased yields and profits to cereal farmers.
Forfattere
Ricardo HolgadoSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag