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
Forfattere
Frank Asche Kristin Helen Roll Ragnar TveteråsSammendrag
Det er ikke registrert sammendrag
Forfattere
Tor J. JohansenSammendrag
Dormancy in a potato tuber prevents sprout growth even under optimal sprouting conditions and is the first stage in the physiological ageing process. The intensity and duration of this phase differs between genotypes (cultivars) and may also be affected by environmental conditions both during tuber bulking and early storage. The current study aimed at finding how simulated high latitude growth conditions influence dormancy and the physiological age of tubers to be used as seed potatoes. In a controlled climate at natural light conditions, tubers grown at a low temperature (9°C) had 2-3 weeks shorter dormancy than tubers grown at higher temperatures (15 and 21°C). In tubers grown at artificial light conditions, day-lengths (12, 18 or 24 h) did not affect dormancy significantly. A post-harvest treatment with a low temperature (one month at 4°C and subsequently 18°C) reduced dormancy by 2-3 weeks in tubers from the highest growth temperatures (15 and 21°C) in comparison with constant 18°C post-harvest. After the lowest growth temperature (9°C) the duration of dormancy was not affected by post-harvest temperature treatments. Physiological age was determined by sprouting characteristics after winter storage. At this stage the sprouting capacity was highest in tubers originating from the lowest and the highest growth temperatures. Further, the number of sprouts per tuber was higher in tubers grown at 9°C than at 15 or 21°C. These results were not correlated with duration of dormancy after the various treatments, suggesting that temperatures may affect dormancy and physiological ageing independently. The present results show that dormancy may be shortened by low grow temperatures, and similarly by low post-harvest temperatures at higher growth temperatures.
Forfattere
Md Hafizur Rahman Trine Lund Ian BrycesonSammendrag
Salinity increase has been one of the major problems for traditional agricultural practices in coastal Bangladesh for several decades, but very few studies have been conducted on effects of salinity on agrobiodiversity in this area. This study investigated the salinity effects on agro-biodiversity in rice (Oryza sativa L.), vegetables, and fruit trees in three coastal, rural villages; Putia (Satkhira district), Srifaltala (Bagerhat district) and Hogolbunia (Khulna district). Information was collected by participatory rural appraisal methods including transect walks, group discussions, key informant interviews, and 121 personal interviews from July to December 2006. The study revealed that increased salinity had significant negative impacts on the overall agro-biodiversity. From 1975 to 2006 the number of indigenous rice varieties declined from seventeen to zero in Putia, from twelve to nine in Hogolbunia and from fifteen to two in Srifaltala. The encroachment of shrimp ponds near the homestead, and cultivation of high yielding, salt-tolerant rice varieties contributed to the decline of indigenous rice varieties. The occurrence of vegetable and fruit tree species declined from 1975 to 1990. The farmers appeared generally unaware of the importance of conservation of seeds and local landraces. This paper highlights factors directly and indirectly influencing farmers’ agricultural practices, and contributes to the discussion as to how environmental changes influence agro-biodiversity conservation and food production. The large reduction in agro-biodiversity, largely induced by increasing salinity, is alarming and threatens the Bangladeshi farmers’ ability to continue crop cultivation and thus their livelihood.
Forfattere
Roman Gebauer Daniel Volařík Josef Urban Isabella Børja Nina Elisabeth Nagy Toril Eldhuset Paal KrokeneSammendrag
Conifers and other trees are constantly adapting to changes in light conditions, water/nutrient supply and temperatures by physiological and morphological modifications of their foliage. However, the relationship between physiological processes and anatomical characteristics of foliage has been little explored in trees. In this study we evaluated needle structure and function in Norway spruce families exposed to different light conditions and transpiration regimes. We compared needle characteristics of sun-exposed and shaded current-year needles in a control plot and a thinned plot with 50% reduction in stand density. Whole-tree transpiration rates remained similar across plots, but increased transpiration of lower branches after thinning implies that sun-exposed needles in the thinned plot were subjected to higher water stress than sun-exposed needles in the control plot. In general, morphological and anatomical needle parameters increased with increasing tree height and light intensity. Needle width, needle cross-section area, needle stele area and needle flatness (the ratio of needle thickness to needle width) differed most between the upper and lower canopy. The parameters that were most sensitive to the altered needle water status of the upper canopy after thinning were needle thickness, needle flatness and percentage of stele area in needle area. These results show that studies comparing needle structure or function between tree species should consider not only tree height and light gradients, but also needle water status. Unaccounted for differences in needle water status may have contributed to the variable relationship between needle structure and irradiance that has been observed among conifers.
Forfattere
jihong liu clarke Even Sannes Riiser Ingrid Holtsmark Sonja Klemsdal Sadhu Leelavathi Andreas Lössl Vanga S. Reddy Nagothu U. Sekhar Hege Særvold Steen Sathyamangalam Swaminathan Rebekka ØvstegårdSammendrag
Dengue viruses (Flavivirus) are mosquito-borne human pathogens with a worldwide prevalence. There are four antigenically-related dengue virus serotypes, DEN-1 to DEN-4, which cause serious problems of morbidity and mortality. Dengue is emerging rapidly as one of the most important public health problems in countries of the Asia-Pacific region with nearly 1.8 billion people in the region at risk, compared to an estimated total of 2.5 billion globally (WHO 2009). The disease has resulted in widespread social and economic problems, especially among the poor, who are the most vulnerable group. There is currently no vaccine to prevent dengue virus infection making it difficult to control and manage the disease, although considerable efforts have been made, including vector control, sanctions, law enforcement and public education (www.who.int). A DEN vaccine must be tetravalent, as immunity to a single serotype does not offer cross-protection against the other serotypes the yeast Pichia pastoris. In this study, we aim to develop a similar envelope domain III (EDIII)-based chimeric antigen which elicits neutralizing antibodies against all four DEN serotypes. The antigen will be expressed in tobacco chloroplasts, aiming for a cost-effective and safe production system by joint efforts of Indo-Norwegian bilateral collaboration.
Forfattere
Sigbjørn Stokke Silje Vang Jon Martin Arnemo Magnus Hansson Ole Roer Asle Stokkereit Erling L. Meisingset Børge Wahl Ingmar Slettemark Bjørnar Asmund Johnsen Gundula Bartzke Christer Moe Rolandsen Erling Johan SolbergSammendrag
Norge har lange tradisjoner for å utøve jakt og fiske, og det er fokus på at dette skal skje innen etisk forsvarlige rammer. I de siste 25 årene har spesielt hjorteviltet blitt en viktigere jaktressurs og i takt med dette har kravene til jaktutøvelse blitt skjerpet. I dag kreves det aktiv opplæring av nye jegere, samt en årlig skytetrening med innlagte tester for storviltjegere. I tillegg er hunden blitt en viktigere faktor, både for å drive fram viltet og for å finne eventuelle skadde dyr. Det stilles nå krav til at en godkjent ettersøkshund er tilgjengelig ved jakt på både elg, hjort og rådyr. Disse hundene skal ha bestått en ferskspor- og en blodsporprøve for å bli godkjent. Imidlertid foregår det ingen testing av ettersøkshundenes evne til å følge ett og samme dyr, noe som er påkrevet dersom intensjonen med kravet om ettersøkshund skal oppfylles. Det har nylig blitt vist at ettersøkshunder som sporet bjørn i liten grad evnet å følge den bjørnen de var satt til å spore. Direktoratet for naturforvaltning (DN) nedsatte derfor i 2010 en kontaktgruppe bestående av representanter fra DN, Norges Jeger- og Fiskerforbund samt Norsk Kennel Klub i den hensikt å evaluere den nåværende ordningen med opplæring og godkjenning av ettersøkshunder. Gruppas mandat var å gå gjennom gjeldende forskrift og instruks, samt å fremme forslag om nødvendige endringer basert på nyervervet kunnskap. Gruppa ønsket spesifikt å se på hvorvidt hunder som var godkjent etter ulike godkjenningsordninger fungerte etter hensikten. Norsk institutt for naturforskning (NINA) ble i den sammenheng forespurt om å gjennomføre evalueringen. For å evaluere hvorvidt en ettersøkshund evner å følge et spesifikt hjorteviltindivid, valgte vi å teste ettersøksekvipasjer (hund og fører) i forhold til GPS-merkede individer av elg og hjort. Til dette fikk vi disponere 13 GPS-radiomerkede elger som Faun Naturforvaltning administrerer i Gardermoenområdet, samt 5 GPS-radiomerkede hjorter fra Hordahjortprosjektet. Senderne ble så reprogrammert til å registrere dyrenes posisjoner hvert 5. minutt. I forkant av testene ble elgene eller hjortene oppsøkt og skremt av en person, hvorpå dyreindividets siste posisjon før skremming ble merket, og den umiddelbare fluktretningen ble registrert. Hvert av ettersøksdyrene ble observert direkte for å forsikre oss om at ingen medfølgende, umerka individer skulle kunne villede hunden. Ettersøksekvipasjen ble siden satt til å spore dyret etter en tidsforsinkelse på 2-22 timer, og fikk anledning til å holde på i en time før ettersøket ble avsluttet. I likhet med ettersøksdyrene ble sporruta til ettersøksekvipasjene registrert ved bruk av en GPS. Vi evaluerte så ekvipasjenes sporingsevne ved å sammenligne sporruta til ettersøksekvipasjen med sporruta til ettersøksdyret. NØKKELORD Norge, Akershus, Gardermoen, Hordaland, ettersøk, ettersøkshund, id-sporing, fersksporprøve, blodsporprøve, elg, hjort, GPS, GIS, radiomerking, modellering, skadeskyting KEY WORDS : Norway, Akershus, Gardermoen, Hordaland, tracking down wounded animals, dog used to track down wounded animals, idtracking, trials on fresh tracks, trials on blood-tracks, moose, red deer, GPS, GIS, radio-collaring, modelling, wounding
Sammendrag
We used two datasets of 14C analyses of archived soil samples to study carbon turnover in O horizons from spruce dominated old-growth stands on well-drained podsols in Scandinavia. The main data set was obtained from archived samples from the National Forest Soil Inventory in Sweden and represents a climatic gradient in temperature. Composite samples from 1966, 1972, 1983 and 2000 from four different regions in a latitude gradient ranging from 57 to 67oN were analysed for 14C content. Along this gradient the C stock in the O horizon ranges from 2.1 kg m-2 in the north to 3.7 kg m-2 in the southwest. The other data set contains 14C analyses from 1986, 1987, 1991, 1996 and 2004 from the O horizons in Birkenes, Norway. Mean residence times (MRT) were calculated using a two compartment model, with a litter decomposition compartment using mass loss data from the literature for the three first years of decomposition and a humus decomposition compartment with a fitted constant turnover rate. We hypothesized that the climatic gradient would result in different C turnover in different parts of the country between northern and southern Sweden. The use of archived soil samples was very valuable for constraining the MRT calculations, which showed that there were differences between the regions. Longest MRT was found in the northernmost region (41 years), with decreasing residence times through the middle (36 years) and central Sweden (28 years), then again increasing in the southwestern region (40 years). The size of the soil organic carbon (SOC) pool in the O horizon was mainly related to differences in litter input and to a lesser degree to MRT. Because N deposition leads both to larger litter input and to longer MRT, we suggest that N deposition contributes significantly to the latitudinal SOC gradient in Scandinavia, with approximately twice as much SOC in the O horizon in the south compared to the north. The data from Birkenes was in good agreement with the Swedish dataset with MRT estimated to 34 years.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Gene expression levels (PAL, CCR1, HCT1, and CAD for the phenylpropanoid pathway, PX3 peroxidase, and CHI4 class IV chitinase), lignin, and soluble and cell wall bound phenolic compounds in bark and sapwood of Picea sitchensis clones inoculated with Heterobasidion annosum s.s. were compared before and 3 days after wounding and artificial inoculation, at site of inoculation and 1 cm above the inoculation site. In bark all genes were up-regulated at the site of inoculation but, except for CAD, not in the distal zone. In sapwood all genes were down-regulated, except for PX3 and CHI4; PAL, CCR1, HCT1 and CAD were present at lower levels around the inoculation site than in the distal zone. Compared to wounding only, inoculation with H. annosum triggered different CAD, PX3, and CHI4 levels in bark but not in sapwood. Different concentrations of cell wall bound phenolic compounds (unknown2, unknown3, coniferin, astringin, taxifolin, piceid, and isorhapontin) were found in bark after wounding and inoculation compared to constitutive material (i.e. untreated samples), whereas in sapwood concentrations did not differ following treatment. These results indicate that bark of Sitka spruce has a stronger and earlier response to wounding and pathogen inoculation than sapwood.
Forfattere
Tao Zhao Paal Krokene Jiang Hu Erik Christiansen Niklas Björklund Bo Långström Halvor Solheim Anna-Karin Borg-KarlsonSammendrag
Background: Tree-killing bark beetles (Coleoptera, Scolytinae) are among the most economically and ecologically important forest pests in the northern hemisphere. Induction of terpenoid-based oleoresin has long been considered important in conifer defense against bark beetles, but it has been difficult to demonstrate a direct correlation between terpene levels and resistance to bark beetle colonization. Methods: To test for inhibitory effects of induced terpenes on colonization by the spruce bark beetle Ips typographus (L.) we inoculated 20 mature Norway spruce Picea abies (L.) Karsten trees with a virulent fungus associated with the beetle, Ceratocystis polonica (Siem.) C. Moreau, and investigated induced terpene levels and beetle colonization in the bark. Results: Fungal inoculation induced very strong and highly variable terpene accumulation 35 days after inoculation. Trees with high induced terpene levels (n = 7) had only 4.9% as many beetle attacks (5.1 vs. 103.5 attacks m22) and 2.6% as much gallery length (0.029 m m22 vs. 1.11 m m22) as trees with low terpene levels (n = 6). There was a highly significant rank correlation between terpene levels at day 35 and beetle colonization in individual trees. The relationship between induced terpene levels and beetle colonization was not linear but thresholded: above a low threshold concentration of ,100 mg terpene g21 dry phloem trees suffered only moderate beetle colonization, and above a high threshold of ,200 mg terpene g21 dry phloem trees were virtually unattacked. Conclusion/Significance: This is the first study demonstrating a dose-dependent relationship between induced terpenes and tree resistance to bark beetle colonization under field conditions, indicating that terpene induction may be instrumental in tree resistance. This knowledge could be useful for developing management strategies that decrease the impact of tree-killing bark beetles.