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.
2008
Forfattere
Sissel Hansen Marina A. Bleken Bishal SitaulaSammendrag
The effects of fertilization and tractor traffic on N2O emission and CH4 uptake in an agricultural soil were studied in a long-term field trial with different fertilization and soil compaction. The soil was a well-drained sandy loam and the crop rotation was rich in leys and legumes adapted to organic farming practise. The fertilization treatments reported here are: Conventional fertilization practise; compound fertilizer with NH4NO3 (NPK), cattle slurry high, cattle slurry level adjusted to organic fertilization practise (CSO), and an unfertilized treatment. The soil was experimentally compacted by two passes with a tractor, wheel by wheel, shortly before fertilization. Gas fluxes at the soil surface were measured by the soil cover method. Conventional fertilization practise (NPK) resulted in 2.1 to 3.4 times higher N2O emissions than with CSO in uncompacted and compacted soil, respectively, in year 7, and 1.0 and 3.0 times higher in year 9. The accumulated CH4 uptake was reduced by 52 % by soil compaction, 50 % on average by fertilization, and 78 % by soil compaction and fertilization combined. Fertilization with NH4NO3 or cattle slurry had similar effects.
Forfattere
Knut Anders HovstadSammendrag
This study examines the impact of plant litter on seedling establishment in a semi-natural grassland. In a field experiment, seeds of six forbs were sown in plots subjected to either different litter quantities or addition of water extracts of litter. The response to plant litter was species specific. High quantities of litter resulted in a negative response in all species except Anthriscus sylvestris. In some of the species, the response shifted from positive or neutral at intermediate litter quantities, to negative at high litter quantities. This suggests that facilitative effects were present, although inhibitory effects dominated at high litter quantities. The physical effects were generally stronger than the chemical effects. However, water extract of litter inhibited emergence in three of the six species. Filtration using activated carbon removed the negative effect of litter extract, which suggests that the effect was caused by inhibitory compounds adsorbed by activated carbon (e.g. polyphenols) rather than by increased competition in response to nutrients added via the extract.
Forfattere
Inger Sundheim Fløistad Hans Martin HanslinSammendrag
The Christmas tree seedlings typically appear with initial slow growth during the first 2-3 years. In the next couple of years the trees grow well, and then during the final 2-3 years before harvest the growth frequently is too vigorous. This growth rhythm often requires laborious growth regulation by mechanical or chemical methods. A dense concentration of branches on the lower part of the tree tends to allocate a lot of resources to the tree base, which grows wide and heavy. Such trees are costly to cut and transport and difficult to sell. Therefore, the growers want transplants with rapid growth after planting. To satisfy their demand there is a need for better plant materials than what are available today. More knowledge is needed about the relation between seedling quality, their physiological status and the plants response to different planting dates. In the year 2007 a new project "Seedling qualities and establishment routines for a rapid growth start of Abies nordmanniana and Abies lasiocarpa for Christmas tree production" was established in Norway to improve our knowledge of establishment of Christmas trees. Financial support is given by the Norwegian Research Council, "Skogtiltaksfondet" and "Forskningsfondet for Norsk Pyntegrønt Forsøksring".
Forfattere
Ingrid Holtsmark Gunnhild Wærsted Takle May Bente BrurbergSammendrag
The Gram-positive bacterium Clavibacter michiganensis subsp. sepedonicus is the causal agent of bacterial wilt and ring rot of potato. So far, only two proteins have been shown to be essential for virulence, namely a plasmid-encoded cellulase CelA and a hypersensitive response-inducing protein. We have examined the relative expression of CelA and eight putative virulence factors during infection of potato and in liquid culture, using quantitative real-time PCR. The examined putative virulence genes were celB, a cellulase-encoding gene and genes encoding a pectate lyase, a xylanase and five homologues of the Clavibacter michiganensis subsp. michiganensis pathogenicity factor Pat-1 thought to encode a serine protease. Six of the nine assayed genes were up-regulated during infection of potato, including celA, celB, the xylanase gene, and two of the pat genes. The pectate lyase gene showed only slightly elevated expression, whereas three of the five examined pat genes were down-regulated during infection in potato. Interestingly, the two up-regulated pat genes showed a noticeable sequence difference compared to the three down-regulated pat genes. These results reveal several new proteins that are likely to be involved in Clavibacter michiganensis subsp. sepedonicus pathogenicity.
Forfattere
Therese With BergeSammendrag
I konvensjonell korndyrking blir ugraset rutinemessig sprøytet med samme herbiciddose på hele åkeren. Dette til tross for at ugraset ofte er ujevnt fordelt og tilsynelatende opptrer flekkvis i åkeren. En logisk tilnærming av "å sprøyte etter behov" burde derfor være flekksprøyting. Simulerings " og kartleggingsstudier i norsk vårkorn viste at man i gjennomsnitt kan redusere bruken av ugrasmidler med 40 " 60 % dersom man bare behandler de deler av åkeren som har en ugrasbestand over skadeterskelen, dvs. flekksprøyting. For å få til flekksprøyting i praksis er det nødvendig med teknologi som gjør at åkersprøytene kan slås av og på automatisk i forhold til ugrasbestanden. Programvaren "WeedFinder" utviklet av Sintef for dette formålet og som automatisk måler ugrasmengde i digitale bilder ble evaluert. "WeedFinder" vil gi korrekt sprøytebeslutning i 65 - 90 % av observasjonene. Simuleringsstudiene viste videre at det er viktig å tilpasse og optimalisere antall kamera og utforming av sprøytebom. Feltforsøk viste at utbredelsesmønsteret av ugraset har stor betydning for ugrasets biomasse og kornets avlingsnivå, og dermed potensielt for skadeterskler til bruk i flekksprøyting.
Sammendrag
Søtkirsebærtre vart sprøyta med kalsiumoppløysing ei gong kvar veke frå krunbladfall til to veker før hausting. Frukt frå trea som hadde fått kalsiumtilførsel, hadde høgare innhald av oppløyst turrstoff. Det var ikkje signifikante skilnader i farge, fastleik og syreinnhald. Bladgjødsling med kalsium reduserte utviklinga av kutikulære frakturar på fruktene. Fruktene frå kalsiumsprøyta tre mista meir vekt under lagring enn frukter frå kontrolltre. Hjå kontrollfrukter med mange kutikulære frakturar var vekttapet større enn hjå tilsvarande frukter med få frakturar. Hjå frukter som var tilført kalsium som bladgjødsling, derimot, var det ingen skilnad i vekttapet mellom frukter med mange eller få kutikulære frakturar. Dette indikerer at dei kutikulære frakturane i kalsiumsprøyta frukt var mindre alvorlege (djupe). Innhaldet av fenoliske sambindingar var større i kalsiumsprøyta frukt enn i kontrollfrukt. Færre kutikulære frakturar, mindre alvorlege (djupe) frakturar og auka innhald av fenolar kan vera ulike mekanismar for reduksjonen i risikoen for soppsjukdomar som ein observerer i kalsiumsprøyta søtkirsebær.
Sammendrag
The last few years, increasing levels of DON (deoxynivalenol) have been recorded in Norwegian cereals, particularly in oats. In the same period, increased occurrence of F. graminearum has been reported in Norway as well as in the Western part of Europe. There may be several reasons for this change: Climate change, altered distribution of cereal cultivars, pathogen adaptation to cooler regions etc. We aim to clarify whether the increasing occurrence of F. graminearum in Norwegian cereals is connected to a change in the distribution of genotypes of this species. Fifty `old" F. graminearum isolates collected from Norwegian grown cereals during the 1990s will be compared to a similar number of `new" isolates collected in recent years (2005-2007). Isolates from Germany, Russia, Finland and the US will be used for comparisons. The genetic diversity of these about 110 isolates (50 `new", 50 `old" and 10 non-Norwegian isolates) will be investigated by AFLP (amplified fragment length polymorphism). These isolates will also be identified phylogenetically and characterised to chemotype. In addition, some selected isolates will be assessed for aggressiveness on wheat and specific characters potentially important for fungal distribution such as in vitro growth rate, spore production and perithecia formation.
Forfattere
Marit Larsen SekseSammendrag
Rognebærmøllen (Argyresthia conjugella) er den viktigaste insektskadegjeraren på eple i Skandinavia. Rognebærmøllen legg egga sine på rognebær om våren og larvene lever i rognebæra. Fruktproduksjonen i rogn er syklisk, og kvart andre til fjerde år er det for lite bær for rognebærmøllen å leggje egg på. I år med lite rognebær legg rognebærmøllen egga sine på eple i staden. Larvene gneg seg inn i epla og etterlet seg brunfarga gangar. Luktesansen er viktig for mange insekt når dei skal lokalisere vertsplanter. Nokre planter skil ut spesifikke luktstoff som insekta kjenner igjen, men i dei fleste tilfelle er det ikkje så enkelt. Dei fleste planter skil ut mange vanlege luktstoff. Tanken er då at insekta kjenner att vertsplantene gjennom ei blanding av ulike luktstoff, og ikkje basert på eit bestemt luktstoff. Desse luktstoffa er gjerne vanlege i mange planter og må vera til stades i rett blandingsforhold. Luktorganet til insekta er antennene. Antennene er dekka av små hår, sensilla (Fig. 1). Desse håra har små porer i overflata som luktstoffa kan kome inn gjennom. Inne i kvart av desse små håra er det ei eller fleire nerveceller. Desse nervecellene kjenner igjen ulike luktstoff og sender beskjed vidare til hjernen. Nervecellene har protein (luktreseptorar) i cellemembranen som kjenner igjen luktstoff. Nokre luktreseptorar er svært spesifikke medan andre kjenner igjen eit større utval av luktstoff. Når eit luktstoff bind til ein luktreseptor vil det føre til ein nerveimpuls.
Forfattere
Maria Herrero Brita Toppe Trond RafossSammendrag
In November 2002, P.ramorum was detected for the first time in Norway (1). It was isolated from Rhododendron catawbiense imported earlier the same year. After the first detection the Norwegian Food Safety Authority has carried out surveys from 2003 to 2006. The surveys were first directed to nurseries and garden centres. Most of the positive findings were on Rhododendron spp., but one sample of Pieris japonica, one of Kalmia sp., one of Syringa sp. and one of Viburnum sp. were also positive. In 2005 and 2006, P. ramorum was isolated from well-established viburnum and rhododendron plants in private gardens, parks and public greens. Infections were detected on well-established plants from 9 different outdoor sites. While the positive samples from nurseries were spread over the country, the positives found on well-established plants were concentrated in and around the cities of Bergen and Stavanger on the southwestern coast of Norway. This part of the country has cool summers, mild winters and more than 2000 mm of annual precipitation. In 2006, P. ramorum was found in private gardens in the eastern part of the country on young recently introduced plants. P. ramorum was found in 12 import shipments, mainly on rhododendron, but also on a viburnum sample.
Forfattere
Matias Pasquali Erik Lysøe Kye-yong Seong Sonja Klemsdal J.R. Xu Li-Jun Ma H. Corby KistlerSammendrag
To understand trichothecene accumulation and the infection cycle of the head light pathogen Fusarium gramineaum sesu stricto, fungal gene expression profiles were monitored during plant infection using the F. graminearum Affymetrix GeneChip. Strains containing mutations in genes for three transcription factors were found to control trichothecene accumulations in planta and pathogenicity. Expression profiles were compared between wildtype and these mutants during infection of wheat. Mutants deleted for the StuA gene were greatly decreased in sporulation and produced no perithecia in culture. Unlike stuA mutants in F. oxysporum, F. graminearum stuA mutants were greatly reduced in pathogenicity. Reducd pathogenicity may be due to decreased trichothecene levels in planta, which in the mutant were two-fold in either tri6 or tri10 deleted strains. A model for global regulation and cross pathway control of sporulation, mycotoxin biosynthesis and pathogenicity will be presented.