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.
2010
Forfattere
Lars Tørres HavstadSammendrag
Three different seed vigour tests, Accelerated ageing (AA), Germination index (GI) and Polyetylenglycol (PEG), were evaluated with regard to ranking six reference seed lots of ‘Grindstad" timothy (Phleum pretense L.) and ‘Lea" red clover (Trifolium pratense L.) according to their physiological potential for storage. The seed reference lots, which all had equally high standard germination percentages, had sustained different degrees of ageing before examination. In timothy, both the AA-test and the GI-test managed well to separate the low-vigour seed lots, having a poor storage potential, from the high-vigour seed lots with better storage longevity. The clearest separation was obtained using the GI-test, either as complete test (six out of six seed lots was significantly separated) or as a simplified test (five out of six seed lots was significantly separated). The germination index of the two tests was based on counting of germinating seeds either on a daily basis for ten days or after counting on day 3 and day 5, respectively. Also the AA-test managed to separate five out of six seed lots of timothy after optimal treatment for 56 h at 45oC. In red clover, the AA-test gave the clearest separation between seed lots. At optimal conditions for 24 h at 45oC, as many as five of the six red clover seed lots could significantly be separated from each other. The recommended seed vigour test for timothy (GI-test) and red clover (AA-test for 24 h at 45oC) has later been adopted for use in practical seed testing routines at the Norwegian National seed laboratory.
Sammendrag
The production of hydrogen in green algae is catalyzed by FeFe- hydrogenases, which have high conversion efficiency and high oxygen sensitivity. Most green algae analyzed to date where hydrogenase genes are detected, have been shown to contain two distinct hydrogenases. However, very little is known about which functions the two different enzymes represent. There are also many unknowns within the mechanisms behind hydrogen production as to the roles hydrogenases play under different conditions, and consequently also about the potential for optimization of a hydrogen production process which could be found in this respect. The presented study focuses on the possibility for presence of more than two hydrogenases in a single green alga. A large number of degenerate primers were designed and used to produce 3"-RACE products, which in turn were used to design gene specific primers used for PCR and 5"-RACE reactions. The sequences were aligned with known algal hydrogenases to identify products which had homology to these. Products where homology was identified were then explored further. A high number of clones from each band were sequenced to identify products with similar lengths which would not show up as separate bands on a gel. Sequences found to have homology with algal hydrogenases were translated into putative amino acid sequences and analyzed further to obtain detailed information about the presence of specific amino acids with known functions in the enzyme. This information was used to evaluate the likelihood of these transcripts coding for true hydrogenases, versus hydrogenase-like or narf-like proteins. Conclusion: Evidence showing that Chlamydomonas noctigama is able to transcribe three genes which share a significant number of characteristics with other known algal FeFe-hydrogenases is presented . The three genes have been annotated hydA1, hydA2 and hydA3.
Forfattere
Mette Vaarst Christine Leeb Pip Nicolas Stephen Roderick Gidi Smolders Michael Walkenhorst Jan Brinkman Solveig March Elisabeth Stöger Elisabeth Gratz Vonne Lund Britt I.F. Henriksen Inger Hansen Madeleine NealeSammendrag
Good animal health and welfare is an explicit goal of organic livestock farming, and will need continuous development and adjustment on the farms. Furthermore, the very different conditions in different regions of Europe calls for models that can be integrated into local practice and be relevant for each type of farming context. A European project with participants from seven countries have been established with the aim of developing principles for animal health and welfare planning in organic dairy farming, based on a process where knowledge about the status within a given herd will be included as background for taking decisions and planning future improvements. An important part of the planning process is communication with other farmers as well as animal health and welfare professionals (veterinarians and advisors). Other principles such as systematic evaluation of how the improvements work in the farm ensure the continuity of the planning process. This presentation gives an overview over the current animal health and welfare planning initiatives in the participating countries and lines up the principles which are being gradually implemented in partner countries in collaboration with groups of organic farmers and organisations.
Forfattere
Carina E. Johansen Christian Lydersen Paul Eric Aspholm Tore Haug Kit M. KovacsSammendrag
Complete gastrointestinal tracts from 257 ringed seals (Pusa hispida) from Svalbard, Norway, were examined for helminth parasites. Three different helminth groups were recorded (acanthocephalans 61.1%; nematodes 38%; cestodes 0.9%). Acanthocephalans (Polymorphidae) and cestodes (Anophryocephalus and Diphyllobothrium sp(p)., as well as unidentified species, were confined to the intestines. The anisakid nematodes Phocascaris phocae, Pseudoterranova sp(p)., Anisakis sp(p)., and Phocascaris/Contracaecum sp(p). were recorded in both stomachs and the anterior part of the small intestines. The abundance of nematodes and acanthocephalans varied significantly with sampling location of the seal hosts. This is likely due to the relative prevalence of Arctic versus Atlantic water in the different fjord systems, which strongly influences the age class and species of fish available as prey for the seals. Adult male ringed seals had significantly higher abundances of nematodes than did adult females or juveniles. Adult males also had significantly higher abundances of acanthocephalans than did adult females, but were not significantly different from juveniles in this regard. Nematode abundance increased significantly with age of male hosts, but this trend was lacking in female seals. Infection parameters appeared to be related to differences in the age of polar cod (Boreogadus saida) exploited by male, female, and juvenile seals.
Forfattere
May-Guri SaethreSammendrag
Urban and peri-urban (UPU) horticulture provides an increasingly important source of income in African countries. A major factor driving the importance of UPU gardening is an increasing marketing opportunity for a growing population of unemployed and unskilled youths in the cities. The potential of UPU gardening is severely undermined by a number of production constraints. Recent field diagnoses in Benin identified severe pest problems and revealed alarming pesticide practices in the UPU areas. Several major pest problems are direct consequences of pesticide abuse that 1) destroys biodiversity required for natural/biological pest control, 2) causes pesticide resistance and pest resurgence and 3) poses personal and environmental hazards. Increasing pesticide use among vegetable producers in UPU gardens in Benin has induced resistance to insecticides in some insect pests. The misuse of pesticides often results in mild to severe human poisonings. Chronic consequences of prolonged exposure to pesticides lack documentation. Additional negative effects are insecticide resistance in insect vectors because of leakage of insecticides to mosquito breeding sites. Insecticide resistance in Anopheles mosquitoes is threatening the success of malaria control programmes. Pesticides which have been banned internationally are commonly used in UPU vegetable production in Africa. Consumer"s consumption of pesticide residues through contaminated products gets little attention. The link between agriculture, environment and health is evident, and climate change contributes to increase already existing challenges.
Sammendrag
The liquid fertilizers (1) Calcinit (Ca NO3)2)+ Superba, (2) Arena Crystal, (3) Flex, (4) Plant Marvel, (5) Sea Power and (6) Sea Power + Superba were evaluated in two greenhouse experiments growing Agrostis stolonifera on columns filled with 30 cm USGA-spec. sand (ignition loss 1.4%, pH (H20) 5.6, CEC 2.7 meq/100 g dry soil) over 10 cm gravel. In expt. 1 the products were compared at weekly rates of 0.1 and 0.2 kg N/100m2 combined with two irrigation levels (1 x ET and 2x ET) during an 8 wk grow-in period; in expt. 2 as maintenance fertilizer to established turf at weekly rates of 0.05 and 0.1 kg N/100m2. Based on weekly determination of visual turfgrass quality and clipping yields, the ranking of fertilizers in the grow-in trial were Sea Power + Superba > Sea Power > Plant Marvel = Flex > Arena Crystal > Calcinit + Superba. Given as maintenance fertilizer, Plant Marvel and Arena Crystal gave higher visual quality and less invasion of moss than Sea Power, the other fertilizers producing results that were not significantly different. The results are discussed in relation to nitrogen form and the content of other nutrients in the various products.
Forfattere
Linda Bergaust Hans Ragnar Norli Dag Ekeberg Camilla Stene Hanne DevleSammendrag
The accumulation of brominated flame retardants (BFRs) in the environment raises concern in light of observed detrimental effects on wildlife as well as on public health. We here present a recently modified method for the identification and quantification of the following selection of bromodiphenyl ether (BDE) flame retardants: BDE-17, -47, -66, -100, -153 and -183, in soil and sediments, using a new extraction procedure followed by gas chromatography mass spectrometry (GC-MS). Low- and high- resolution mass spectrometry (LRMS and HRMS, respectively) were compared and the latter was found to be superior with respect to both sensitivity and linear range. At LRMS mode the linear range was 3.8 - 19.2 ng/g, while the use of HRMS more than doubled the linear range to 1.9 - 38.4 ng/g. Both methods were tested with regards to matrix associated effects on the limit of detection and quantification. The use of HRMS yielded equal sensitivity for standards in solution and matrix. This was not the case when using LRMS. Here the limits of detection and quantification were severely elevated by the matrix. Recoveries were comparable, but slightly higher at LRMS mode (77.0 - 121.9%) compared to HRMS (83.2 - 115.3%). The method described here is high throughput, low cost and will prove valuable in monitoring the levels of BFRs in the environment.
Forfattere
May Bente Brurberg Xiaoren Chen May Bente Brurberg Sonja KlemsdalSammendrag
The oomycete Phytophthora cactorum causes crown rot in strawberry, resulting in big economic losses. To unravel the molecular mechanisms that are involved in the pathogenicity of P. cactorum on strawberry, two strategies were followed, SSH cDNA library and effector specific differential display (ESDD). Two cDNA libraries were made, enriched for P.cactorum genes upregulated during infection of strawberry or in in vitro germinating cysts (a developmental stage essential for infection). Recent characterization of oomycete AVR/effector genes revealed that they encode proteins with conserved RxLR-dEER motifs required for translocating these effectors into host cells. The presence of such a conserved "tag" has provided a tool for discovering the otherwise structurally diverse effector genes. To select RxLR effector genes from P. cactorum, ESDD was performed on seven cDNA populations including four developmental stages (mycelium, sporangia, zoospores,germinating cysts) as well as three time points during infection (3, 5, 7 days postinoculation),using RxLR and EER primers. Using these strategies more than 230 gene fragments were isolated. Nearly 30 % of the genes could not be assigned a coding function, using sequence similarity-based function prediction, because either no similar sequences were detected or similarities were found only to putative proteins with unknown function (mostly oomycete). However, several genes potentially relevant for pathogenicity, including several putative RxLR effector and elicitor genes were discovered. The expression of 27 of these genes was studied in detail using real-time RT- PCR, and their upregulated expression during infection relative to dispersal propagules (sporangia) were confirmed for all but one.
Sammendrag
Sturite et al. (2007) investigated growth and death of the major parts of white clover (Trifolium repens L. cv. "Snowy") plants in pure stand and in mixture with meadow fescue (Festuca pratensis L. cv. "Fure") in a combined plot and root window experiment in Norway (60°42"N, 10º51"E). Leaves, stolons and roots were tagged and their lifespan was monitored in harvested and non-harvested stands during two experimental years. The longevity of leaves and petioles ranged from 21 to 86 d (mean = 59 d). About 60% of the leaves produced during the growing season turned over before the autumn. Of the remaining leaves, 70-80 % were dead or had disappeared by the subsequent spring. The lifespan of sections of the main stolons ranged from 111 to over 677 d (mean = 411 d). In particular, stolon sections close to the parent fragment of undisturbed plants were long lived, while sections towards the terminal bud overwintered more poorly and had a much shorter lifespan. The longevity of roots was from 27 to 621 d (mean = 290 d) and was higher for roots appearing in spring and autumn than in summer. Harvesting significantly reduced the longevity of stolons and caused an increased fragmentation of the white clover plant but did not decrease leaf/petiole or root lifespan.
Forfattere
Eszter Tóth Zoltan Barcza Márta Birkás Györgyi Gelybó József Zsembeli László Bottlik Kenneth J Davis László Haszpra Anikó Kern Natascha Kljun Sándor Koós Györgyi Kovács Attila Stingli Csilla FarkasSammendrag
An overview of carbon dioxide (CO2) exchange and soil respiration measurements is given for representative Hungarian agroecosystems. We present results of long term atmosphere/biosphere CO2 exchange measurements carried out at the Hungarian tall tower site (Hegyhátsál). Tall tower net ecosystem exchange (NEE) measurements provided consistent estimates of landscape-wide carbon dioxide dynamics. During the period of 1997-2008 the region mostly behaved as a net CO2 sink on annual scale. Year-round NEE was in the range of 352±49 g C m 2 year-1 and 43±9 g C m-2 year-1 (negative values indicate uptake). The measurements are representative to a mixture of arable lands with small contribution from other biome types. Effects of different soil tillage methods - applied in two long term tillage experiments (Józsefmajor, Karcag) and in a peach orchard (Vác) - on soil CO2 emission are also introduced. Soil respiration rate highly depended on the depth of soil disturbance and on the date of the measurements; CO2 emissions measured immediately after tillage applications and during the vegetation period showed contradictory tendencies. Results obtained from a newly developed laboratory CO2 emission measurement method indicated strong coherences between soil carbon dioxide fluxes and soil water potential values.