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
Sammendrag
Poinsettia (Euphorbia pulcherrima Willd. Ex Klotzsch), is a contemporary symbol of Christmas in most parts of the world. Today, Europe and North America represent the largest volume of production and sales, but demand is growing quickly in the other regions as poinsettia becomes more popular each year. In Norway, poinsettia is one of the most important pot plants, with a yearly production close to 6 million plants. Its ornamental value and innovation potential have laid the foundation for extensive research in Norway and elsewhere. Poinsettia mosaic virus (PnMV) is a RNA virus that belongs to the family Tymoviridae. Infection of poinsettia plants with PnMV results in mosaic symptoms during parts of the growing season and decrease the commercial value of this ornamental plant. Thus, growers are interested in the potential benefits of growing PnMV-free poinsettias. PnMV-free poinsettia plants can be obtained by heat treatment or in vitro culture of apical meristems, which are time-consuming and cost-ineffective methods. There is thus an urgent need for a new approach, like Agrobacterium-mediated transformation, which can overcome these difficulties. We have therefore developed an Agrobacterium-mediated transformation approach for poinsettia. Transgenic poinsettia plants with improved resistance against PnMV by expressing hairpin RNA constructs which targeted various regions of the virus genome were produced. Mechanical inoculation of PnMV and subsequent enzyme-linked immunosorbent assay (ELISA) confirmed the PnMV resistance. The siRNA analysis has demonstrated gene silencing mediated resistance. The PnMV resistant transgenic poinsettia lines produced are in the process of being commercialized. Because poinsettia is a non-food, non-feed plant and is not propagated through sexual reproduction, this is likely to be more acceptable even in areas where genetically modified crops are currently not cultivated.
Forfattere
Thomas Hartnik Line Sverdrup John JensenSammendrag
lpha-cypermethrin, a synthetic pyrethroid, is used as an insecticide in agricultural settings, and increasingly replaces organophosphates and carbamates due to lower application rates and lower mammal toxicity. As very little is known about the acute and chronic toxicity for soil living organisms, this study investigated acute and sublethal toxicity of alpha-cypermethrin for four terrestrial invertebrate species in an agricultural soil from Norway. Bioassays with the earthworm Eisenia fetida, the potworm Enchytraeus crypticus, the springtail Folsomia candida and the land snail Helix aspersa were performed according to slightly modified versions of OECD- or ISO-guidelines and resulted in median lethal concentrations (LC50) of >1000 to 31.4 mg/kg and sublethal no-effect-concentrations (NOEC) of 2.51 to 82 mg/kg. A high acute-to-chronic ratio (ACR) was found in especially the earthworms. Interspecies differences in sensitivity may be explained by differences in exposure and differences in metabolisation rate. When based on measured pore water concentrations, terrestrial species appear overall to be about one order of magnitude less sensitive than aquatic species. Effect assessments conducted according to European guideline for risk assessment of pesticides reveal that assessments based on acute toxicity tests are not always conservative enough to warrant environmentally safe concentrations in soil. Mandatory incorporation of sublethal toxicity data will ensure that also in regions with temperate climate effects of pesticides on populations of soil living organisms are unlikely.
Sammendrag
Healthy seed is important for a successful plant production and organic cereal production must rely on management of seed-borne diseases without synthetic seed treatment chemicals. Inoculum thresholds, i.e. the level of seed borne inoculum that can be accepted, are needed for organic cereal production. In general, significantly lower infection frequencies of seed borne diseases are recorded on seedlings than on seed. The aim of the work presented was to compare transmission of Drechslera teres from barley seeds to seedlings in soils with different content of organic materials. Experiments with two seed lots (93 % and 94 % D. teres, respectively) have been carried out in greenhouse with 8 different soils collected in different cereal growing regions. 100 seeds with 3 replicates from each seed lot were planted in each soil type and placed for emergence at 12 oC. Percent emergence and percentage seedlings with symptoms of net blotch were recorded at BBCH 10-12. The net blotch frequency as average for the two seed lots ranged from 11 to 21 % in the different soils. Higher content of organic materials resulted in less infection frequencies. A correlation was found between the amount of organic materials in the soil and % net blotch (r = -0.83, P = 0.009). Experiments will be repeated with less infected seed lots.
Forfattere
Anne Kristine Søvik Pål Tore MørkvedSammendrag
Constructed wetlands (CWs) in the agricultural landscape reduce non-point source pollution through removal of nutrients and particles. The objective of this study was to evaluate if measurements of natural abundance of 15NO3 " can be used to determine the fate of NO3 " in different types of small CWs treating agricultural runoff. Nitrogen removal was studied in wetland trenches filled with different filter materials (T1 " sand and gravel; T3 " mixture of peat, shell sand and light-weight aggregates; T8 " barley straw) and a trench formed as a shallow pond (T4). The removal was highest during summer and lowest during autumn and winter. Trench T8 had the highest N removal during summer. Measurements of the natural abundance of 15NinNO3 " showed that denitrificationwas not significant during autumn/winter, while it was present in all trenches during summer, but only important for nitrogen removal in trench T8. The 15N enrichment factors of NO3 " in this study ranged from"2.5 to "5.9"(T3 and T8, summer), thus smaller than enrichment factors found in laboratory tests of isotope discrimination in denitrification, but similar to factors found for denitrification in groundwater and a large CW. The low enrichment factors compared to laboratory studies was attributed to assimilation in plants/microbes as well as diffusion effect. Based on a modified version of the method presented by Lund et al. [Lund LJ, Horne AJ, Williams AE, Estimating denitrification in a large constructed wetland using stable nitrogen isotope ratios. Ecol Engineer 2000; 14: 67"76], denitrification and assimilation were estimated to account for 53 to 99 and 1 to 47%, respectively, of the total N removal during summer. This method is, however, based on a number of assumptions, and there is thus a need for a better knowledge of the effect of plant uptake, microbial assimilation as well as nitrification on N isotopic fractionation before this method can be used to evaluate the contribution of dinitrification in CWs.
Forfattere
C Rahn K Zhang R Lillywhite C Ramos J de Paz J Doltra Hugh Riley M Fink C Nendel K Thorup-Kristensen A Pedersen F Piro A Venezia C Firth U Schmutz F RaynsSammendrag
The production of fresh vegetables within Europe relies on intensive rotations, supported by large inputs of nitrogen from fertiliser and organic sources which is required to maintain the yield and quality of produce demanded by the multiple retailers and their customers. Most field vegetable crops use nitrogen inefficiently and often leave large residues of nitrogen (either as unused fertiliser or crop debris) in the soil after harvest, which can potentially cause damage to soil, water and aerial environments. Funding from the EU Commission has enabled the development of a new computer model, EU-Rotate_N, which can be used to investigate the fate of nitrogen supplied to rotations of field vegetable crops. EU-Rotate_N was used to examine the effects of applying existing codes of Good Agricultural Practice (GAP) on the economic and environmental performance of several case study rotations in Europe. In some cases, following GAP, led to significant reductions in N losses without affecting the farmer"s gross margin but in others reduced gross margin without reducing N losses significantly. This paper will briefly describe the development of the model and will present the results of several case studies to show the effects of applying GAP on the performance of horticultural rotations.
Forfattere
Ingvild Wartiainen Torsten Eriksson Weiwen Zheng Ulla RasmussenSammendrag
Biological nitrogen fixation (BNF) is an important source of nitrogen input in many natural ecosystems. The rice production today depends on large amounts of chemical nitrogen fertilizer, which is an environmental hazard in rice producing areas. Better exploitation of BNF is one way to reduce the use of chemical nitrogen fertilizer in the future. In this study the active diazotrophic community was investigated in nitrogen fertilized and un-fertilized rice field soils in Fujian Province, southeast China by PCR - DGGE of nifH mRNA, and the potential community by PCR - DGGE of the nifH gene. A total of 45 sequences representing 33 different sequence types were recovered from the DGGE gels. The retrieved cDNA sequences representing the active population of diazotrophs both in fertilized and un-fertilized soils dispersed throughout the nifH clades (alpha-, beta- and gamma Proteobacteria, Firmicutes and Archaea). Thirteen of the sequence types were most closely related to Azoarcus endophytes indicating widespread associations between heterotrophic nitrogen fixing bacteria and rice (Oryza sativa). The majority of the 13 sequence types were identified from the cDNA samples, showing that the Azoarcus might be an important active nitrogen fixing diazotroph in the paddy field. None of the sequence types were closly related to cyanobacteria, nevertheless previous studies from the same area had documented the prescence of cyanobacteira in rice fields. The lack of identified cyanobacteria might be due to template discrimination in the PCR reactions, or low abundance of cyanobacteria compared to heterotrophic nitrogen fixing bacteria.
Sammendrag
Planteparasittære nematoder er små rundormer som skader røttene på korn. Symptomene viser seg som tynn plantebestand, svake planter og mer ugras. I de siste årene viser henvendelser fra produsenter at problemene med nematoder er økende. Prøver med korncystenematoder, rotsårnematoder og stuntnematoder er vanlig. I prøvene hvor resistente sorter for korncystenematoder er dyrket, og skader vises, er ofte rotsårnematoder funnet. Rotsårnematoder er påvist i forbindelse med skader i alle kornarter. I en del av feltene som er undersøkt i Vestfold, Østfold, Agder, Romerike og Buskerud er det vist til dels høge populasjoner av rotsårnematoder.
Sammendrag
Ved økologisk frøavl er førsteårsengene ofte tynne og ugrasfulle. Mange økofrøavlere vurderer derfor alternativ utnyttelse av førsteårsenga. I timotei og engsvingel ble det i disse forsøka oppnådd henholdsvis 16 og 26 % større frøavling i andre engår dersom førsteårsenga ble slått til fôr eller grønngjødsling ca. 15.juni og 5.august enn om førsteårsenga ble treska som frøeng. Frøpartiene fra andre engår inneholdt ikke balderbrå, men forekomsten av kvitkløver i andreårsenga var større etter fôrproduksjon eller grønngjødsling enn etter frøeng i første engår. Kvitkløver og andre kløverarter er uheldig i timoteifrøeng på grunn av problemer med frarensing. I tillegg skaper kløveren konkurranse for graset.
Forfattere
Sølvi Svendsen Siv Fagertun RembergSammendrag
I dagens villahager og parker er det en helt annen sammensetning av planter enn for bare noen tiår siden. I villahagen på 60-tallet var det vanlig å dyrke bær for safting og sylting og frukt for lagring eller konservering til vinterbruk. Utvalget av sommerblomster, stauder, busker og trær har økt, og vi planter andre arter og sorter enn vi gjorde før. I dag velger vi flere arter av trær og busker som ikke er stedegne for Norge, men importert materiale. Det vil si planter som betraktes som eksotiske og annerledes enn det som vokser rundt oss til vanlig. Vi velger kanskje også flere planter for pryd og ikke så mye for nytte lenger, fordi utvalget av grønnsaker, frukt og bær i matbutikkene er stort og alle arter er tilgjengelig hele året. Vi lever et ”hurtigere” liv med mindre tid til å konservere det vi kan høste av naturen. Tidligere hadde konservering av hagens frukt, bær og grønnsaker et økonomisk motiv. Nå er denne typen arbeid noe man gjør for å lage et spesielt produkt eller til en spesiell anledning.
Forfattere
Randi Seljåsen Ove Hetland Gerd Guren Francisco Granados Ingrid Myrstad Siv Nilsen Vibecke HjønnevågSammendrag
Jordskokk er en gammel matplante som er i ferd med å få en ny renessanse. Plantens underjordiske hvite knoller minner om potetknoller, men er mer ujevne i formen og har en helt annen smak og konsistens både i frisk og bearbeidet form. Den karakteristiske og spennende smaken hos jordskokk har lenge vært ettertraktet av kokker på restauranter verden over. Knollene er rike på helsegunstige stoff av typen fruktfiber (fruktooligosakkarider) som blir viet stadig større oppmerksomhet både innenfor tarmhelse, diabetes, overvekt og hjerte kar sykdommer. Stoffene stimulerer også opptak av kalsium og syntese av B-vitaminer i tarmen. Det har i løpet av en tre års periode blitt arbeidet med dyrkningstekniske utfordringer ved økologisk produksjon av jordskokk innenfor et prosjekt finansiert av Statens Landbruksforvaltning. Parallelt med dette har det blitt arbeidet med ulike oppdrag for konservesindustrien for å utvikle bearbeidede produkter av jordskokk. I tilknytning til satsningen er det etablert en dyrkergruppe og en egen nettside med informasjon om jordskokk (www.jordskokk.no). I dette innlegget vil økologisk produksjon vektlegges og presenteres sammen med de mer generelle temaene ved produksjonen.