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.
2003
Forfattere
Christian Uhlig Olavi Junttila Marja-Liisa SutinenSammendrag
The purpose of the present study was to determine frost hardiness in different tissues of E. nigrum and V. myrtillus, and to test the impact of long-term heavy metal pollution on frost hardiness of these species. Above-ground shoots of both dwarf shrubs were collected in early winter along pollution gradients from Cu-Ni smelters in SW Finland and NW Russia, and stored under dark conditions at - 5 °C. Frost hardiness (LT50) was estimated in different plant tissues monthly over a 6-month period. The results showed no changes of frost hardiness in either E. nigrum or V. myrtillus during storage. In both species, different tissues exhibited different degrees of frost hardiness. Results from chemical analysis of plant material showed that levels of Cu in shoots of both species increased up to 10-fold towards the smelters. Frost hardiness in vascular tissue of Empetrum decreased by about 5 °C, and that of Vaccinium by about 2 °C, towards the smelter in SW Finland, while no changes could be observed at the more highly contaminated sites in NW Russia. The results suggest that long-term heavy metal pollution has no direct significant impact on frost hardiness in either E. nigrum or V. myrtillus.
Forfattere
Ronald BjøruSammendrag
Det er ikke registrert sammendrag
Forfattere
Ronald BjøruSammendrag
From a point of near extinction about 50 years ago (1955) - the indigenous sheep of Norway is today spread along the coast from Rogaland in the south to Troms in the north and numbers approx. 30 000 wintering sheep, with some 3-400 owners. This breed of sheep is tough, and utilizes marginal grazing areas, can manage to graze during the winter season in the mild Atlantic climate along the Norwegian coast if the snow layer does not get to deep, and can also manage well without housing. The meat is special, and differs from ordinary sheep meat. This production is therefore low-cost, both concerning buildings and demand for silage or hay, not to mention additional feeding supplements. This - together with utilization of areas not suitable for other production - was the start of the popularity for this sheep, and the breed slowly increased in numbers from 1975 and up to 1990. Since then the number has increased rapidly. During the 1990"s, the producers organized themselves as a company having a high price for the meat as one of the main goals. The success of this marketing project is the main cause for the popularity of the sheep, and the rapid increase in number. This paper/presentation deals with the factors that made this a success, and also looks at the challenges ahead, especially concerning a more regional model for marketing and selling, how to guarantee the quality of the product, and the ethic aspects of this production
Forfattere
Nina JohansenSammendrag
Utvikling og adferd hos Eretmocerus eremicus n.sp. Rose & Zolnerowich (Hymenoptera: Aphelinidae) og denne snyltevepsens evne til å bekjempe bomullsmellus, Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) biotype B på julestjerne, ble undersøk i klimastyrte veksthusrom ved de temperaturene og daglengder som brukes i julestjernedyrkingen. Utviklingen fra egg til voksen tok 15,6, 28,5 og 46,2 dager ved henholdsvis 24 oC, 21 oC and 18 oC. Snyltevepsen brukte 16 % mindre tid på å søke (gå), og 40 % mindre tid til å håndtere vertene (tromming med antennene, undersøke verten med eggeleggingsbrodden og egglegging) ved 18 oC enn ved 24 oC ved en vert-tetthet på 1,8 bomullsmellusnymfer per cm2 bladareal. Tiden som ble brukt til pussing av bein og antenner og til å hvile, økte med henholdsvis 45 og 52 % når temperaturen ble senket fra 24 oC til 18 oC, og antall verter som ble funnet og antall egg som ble lagt ble omtrent halvert, fra henholdsvis 16,5 til 8,9 verter/time og 3,9 til 1,8 egg lagt/time. Egg ble lagt i litt over 20 % av vertene som ble funnet. Flyvingen ble vesentlig redusert ved 18 og 15 oC. I burforsøk med en utslippsrate på 2,5 E. eremicus hunner per voksen bomullsmellus ble en gjennomsnittlig parasitteringsprosent på ca. 80 % ble funnet ved 24 og 21 oC, og bekjempelsen av bomullsmellus var god (96-98 % effekt etter 12 uker). Denne prosenten ble mer enn halvert ved 18 oC. Vesentlig færre verter ble drept som følge av vertsspising ved 18 oC i forhold til 21 og 24 oC. Kontroll av bomullsmellusa ble ikke oppnådd ved 18 oC. Mens temperaturen hadde stor innvirkning på effektiviteten av E. eremicus, hadde daglengden ingen betydning.
Forfattere
Øystein Johnsen Carl Gunnar Fossdal Rüdiger Baumann Jørgen A. Mølmann Ola Gram Dæhlen David ClaphamSammendrag
Det er ikke registrert sammendrag
Forfattere
Øystein Johnsen Carl Gunnar Fossdal Rüdiger Baumann Jørgen A. Mølmann Ola Gram Dæhlen David Clapham Tore SkrøppaSammendrag
Det er ikke registrert sammendrag
Sammendrag
The erosion risk has been assessed on about half of Norway"s approximately 0.7 million hectares of arable crop area. Of this, 20% is classified as being at low risk of erosion, 57% has a medium risk, 17% a high risk and 6% an extremely high risk. The erosion risk is particularly associated with autumn ploughing, which renders the soil especially vulnerable during the snowmelt period. For this reason, about 35-40% of the area is tilled only in spring, and current support of 50-175 Euro ha-1 is given, varied according to erosion risk, in order to encourage this practice. Long-term trials (12-27 years) have been performed with various forms of conservation tillage on representative soil types under varying climatic conditions. Results of these trials indicate that the time of ploughing (spring versus autumn) has little effect on crop yields, even on clay soils. Spring ploughing may, however, delay sowing somewhat. Ploughless systems are generally successful on well-drained loam and clay soils under the relatively dry conditions in southeast Norway, but have proved to be more problematic under wetter conditions, especially on silt and sandy soils. A survey of results is presented, highlighting noteworthy aspects of conservation tillage in Norway. This includes yield results, between-year correlations with weather variables and selected results of how reduced tillage affects soil physical properties.
Forfattere
Halvor SolheimSammendrag
Det er ikke registrert sammendrag
Forfattere
Ricardo Holgado Magne Støen Christer Magnusson Bonsak HammeraasSammendrag
Several species of cyst nematodes in the genus Heterodera attack cereals. The most common, and maybe the most important species, is the cereal cyst nematode (CCN) H. avenae, which was first reported in Norway in 1925. The dominant cereal in Norway is barley, followed by oats and wheat. The acreage grown under wheat has increased by 70% during 1985 to1995. Field damage by cereal cyst nematode is shown as patches with uneven growth, which is most clearly seen in oats; in addition to cereals several species of grass are hosts of some cereal cyst nematodes. This report gives a background to some problems related to cyst nematodes on cereals, and is the result of a recent survey of the genus Heterodera in cereals in Norway. The results are based on the analysis of 220 samples for the years 1995-1998. Nematodes in the genus Heterodera are common in Norwegian cereal fields and have been recorded from the county of Agder in the county of Nordland. In this survey the highest frequencies of occurrence were found in oats and wheat. Earlier studies have demonstrated Ha51 to be the dominant pathotype of H. avenae in Norway. The observed increase in damage may relate to the lack of resistance of Ha51 in current cultivars, and a shift in pathotype frequency of CCN. The increased acreage of wheat and the cultivation of susceptible cereals when used as a pre-crop to oats and wheat could also contribute to the increase in damage. Knowledge of the occurrence and distribution of different species and pathotypes of cyst nematodes on cereals in Norway also needs to be developed. Screening the current cultivars for resistance against cereal cyst nematodes, and finding effective nematode pest control strategies is also urgently needed.
Forfattere
Marianne BechmannSammendrag
The aim of a P index for Norway is to localize fields where measures should be implemented. In contrast to general implementation of measures this will affect only fields with a high risk of P loss and thus, do not put substantial restrictions on fields, which do only have marginal impact on water quality. The P index has been adapted to different geographic regions throughout the U.S.A. If properly constructed, the P index concept may be a valuable tool for managing P losses from agricultural landscapes in Norway. Analysis of existing data that describes the relationship between P loss and site-specific factors is needed for selection of appropriate factors, ratings and weightings for a geographically adapted P index. This review suggests that P-AL may be used as a factor for soil P content, though the relationship between P-AL and runoff of dissolved P needs further investigation. The special factors related to cold climate needs to be evaluated for the P application factor, e.g. release of soluble P from frozen plant residues. The P application factor also needs to be adapted to local methods of P application, including both incorporation of manure on arable land, surface application on pastures and grazed land. The Norwegian erosion risk mapping may form a basis for the erosion factor, though some additional estimates needs to be developed, e.g. the concentrated flow erosion and differences in erosion caused by aspect. A factor for runoff generation may consist of hydraulic conductivity and amount of precipitation. Tile draining creates a need for evaluation of the factor for P loss through subsurface drainage. The connectivity factor is most important for surface runoff, since subsurface water is usually connected to the stream by tiles. The water quality of a recipient in addition to diffuse agricultural pollution depends on the existence of agricultural point sources. Evaluation of the possibilities for using the P index concept in Norway includes an assessment of how many indices are needed to represent the differences in conditions of different areas. The development of P indices represents an easy means of identifying and rank the risk of areas within a catchment as to their vulnerability to P loss.