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
Anne-Grete Roer HjelkremSammendrag
Abstract The thesis is about quantification of uncertainties in complex models. Models are built to describe, explain or predict a real world outcome. It is well known that models are related with uncertainty, and that uncertainties are related to how close the simulation is to the real world outcome. Still, uncertainties are rarely quantified in dynamic models. We have focused on parameter uncertainty and output uncertainty derived from the parameters. Uncertainty originated from the empirical data is integrated into the posterior parameter distributions through the likelihood functions. Additionally, uncertainty related to the representativeness of the collected data to the population has been focused. The Bayesian statistical framework, with the Markov chain Monte Carlo algorithm random walk Metropolis was used for model calibration in the four papers. The algorithm was found simple in idea and implementation into the computer program Matlab, but challenges emerged when the method was used at complex models. In this work these challenges have been pursued together with searching for efficiency improvements in order to make as few model evaluations as possible. Paper I: explores the challenges emerging when applying Bayesian calibration to a complex deterministic dynamic model of snow depth. How prior information and new data affect the calibration process, the parameter estimates and model outputs were demonstrated. Parameter uncertainty and model uncertainty derived from the parameters were quantified, visualized and assessed. The random walk Metropolis algorithm was used and in order to reach convergence more effectively, informative priors, Sivias" likelihood, reflection at the prior boundaries and updating the proposal distribution with parts of the data gave successful results. Methods for objective and correct determination of Markov chain convergence were studied, and the use of multiple chains and the Gelman-Rubin method was found useful. Paper II: presents a dynamic model for snow cover, soil frost and surface ice. The Bayesian approach was used for model calibration and sensitivity analysis identified the non-important parameters. Paper III: shows the importance of splitting the data several times in two for model development and assessment/selection, for the model to fit well to novel data from the system and not only to the specific data at hand. Different models of ascospore maturity of Venturia inaequalis were further developed and compared by the deviance information criterion and root mean square error of prediction to show model improvements, and the analysis of variance was used to show significance of the improvements. Paper IV: examines the potential effects of selection of likelihood function when calibration a model. Since the likelihood function is rarely known for certain, but gives a reasonable quantification of how probable the data are given model outcome, it is of great importance to quantify the effect of using different likelihood functions on parameter uncertainty and on model output uncertainty derived from the parameters.
Forfattere
Stig Morten Thorsen Mats Høglind M. SemenovSammendrag
In grass-based milk and livestock production, winter damage to overwintering grasses may have large economic consequences. In a previous study conducted for Norwegian conditions we assessed the impact of climate change on the winter survival of timothy (Phleum pratense L.) and perennial ryegrass (Lolium perenne L.) using agroclimatic indices and a simulation model of frost tolerance. This study was based on locally adjusted future climate scenarios (two for the period 2071-2100; one for the period 2020-2049) for six important agricultural regions, represented by one location each. Compared with the control period 1961-1990, the future hardening period will be shortened by up to 21 days. As a consequence, the modelled maximum frost tolerance is expected to be reduced by up to 3.9°C and 1.9°C for timothy and perennial ryegrass, respectively, under the warmest scenario. In spite of this reduction, the plants are expected to be hardy enough to withstand the predicted autumn frosts, and we also expect a general reduction in the risk of winter frost injuries. We found that agroclimatic indices are less suitable for assessing the risk of plant injury related to frost and ice encasement in Norway, since they do not account for the dynamics of cold adaptation. Although less snow is expected, in most cases this will not be accompanied by an increase in the risk of ice encasement injuries. However, a slight increase in the number of ice encasement events was predicted for one location. An earlier start of growth was predicted for all locations, accompanied at one coastal location by a slightly increased predicted risk of spring frosts. There is little risk of winter injuries related to frost and ice encasement in the hardier grass species timothy. The better overwintering conditions in general indicate that it will be possible to grow perennial ryegrass in areas where it is not grown today, provided the risk of fungal diseases does not increase. In the present study we are working on a similar analysis for a selection of sites located around the Baltic Sea using local-scale climate scenarios from the ELPIS dataset based on the stochastic weather generator LARS-WG.
Forfattere
Jens Rohloff Per Winge Jahn Davik May Bente Brurberg K Mockaitis V Shulaev SK Randall Atle Bones Muath AlsheikhSammendrag
In order to support functional genomics research in octoploid (Fragaria x ananassa Duch.) and diploid (F. vesca) strawberry, a customized Fragaria microarray chip was developed as a joint collaboration between Graminor Breeding Ltd. and NTNU. F. vesca cDNA sequences were provided by The Center for Genomics and Bioinformatics, Indiana University (an assembly of >3 million reads from GS-FLX Titanium - Roche/454 Life Sciences sequencing), and about 59,000 publicly available Fragaria EST sequences were uploaded from NCBI. In addition, ~190 Mb of preliminary draft genome sequences from F. vesca were provided by the Strawberry Genome Sequencing Consortium (courtesy to V. Shulaev). cDNAs used as templates for probe design were validated by BlastN against the F. vesca draft genome excluding cDNAs of microbial origin. Genes not represented in the cDNA collection were identified by screening F. vesca draft genome against protein sequences from Arabidopsis thaliana, Vitis vinifera, Ricinus communis and Populus trichocarpa. Exon sequences from genes not found in the cDNAs were included. In total, 43723 unique 60-mer probes were designed and the Agilent eARRAY tool was used to produce a 4x44k format microarray chip. Fragaria chip applicability and feasibility for transcriptional profiling was investigated using either abiotic (low temperature) or biotic (pathogenic fungi) stress treatment. Microarray data will be subsequently integrated with other omics data to address gene-regulatory networks and biological functions. Cold acclimation experiments were focused on short- and long-term effects in meristematic tissue, and revealed the up-regulation of ~100 cold-responsive genes (transcription factors, dehydrins, enzymes), and transcripts involved in starch breakdown and raffinose biosynthesis. Beside central metabolism, secondary metabolism was also strongly modulated as seen by changes in the expression of flavonoid biosynthesis-related genes. Time-course studies of transcriptional responses in F. vesca accessions showing contrasting resistance toward the pathogen Phytophthora cactorum are in progress, and will be presented in-depth.
Forfattere
Aslaf Belachew Arne Stensvand Nina Trandem Vitalis Wafula Wekesa Gilberto de Moraes Ingeborg KlingenSammendrag
The co-occurrence of powdery mildew, Podosphaera aphanis, and the two-spotted spider mite, Tetranychus urticae, on strawberry plants requires a strategic use of fungicides to control powdery mildew without harming predatory mites and other beneficial organisms. Sulfur has been used for two centuries to manage powdery mildew and is the only fungicide approved for use in organic strawberry production in Norway. However, there are contrasting reports in the literature about the effect of sulfur on predatory mites and two-spotted spider mite from field studies. Controlled laboratory experiments were therefore conducted on strawberry leaf disks to study the main as well as the interacting effects of sulfur on P. aphanis, T. urticae and the predatory mite, Phytoseiulus persimilis. The following seven treatment combinations: 1) Sulfur + P. aphanis 2) Sulfur + T. urticae 3) Sulfur + P. persimilis 4) Sulfur + P.aphanis + P.persimilis 5) Sulfur + P.aphanis + T.urticae 6) Sulfur + P. Persimilis + T.urticae 7) Sulfur + P.aphanis + P.persimilis + T.urticae and seven parallel treatment combinations with water instead of sulfur (control) were used. Leaf disks were dipped in a sulfur (Thiovit Jet) solution or water and inoculated with P. aphanis after the sulfur/ water had dried on the leaf surface. In treatments with mites, five female T. urticae and one female P. persimilis were added per leaf disk. Preliminary analysis of the results showed that only the predatory mite and sulfur significantly (P ≤ 0.05) affected egg production and mortality of T. urticae. In the treatment that combined sulfur + P. aphanis + P. persimilis + T. urticae a significantly reduction in T. urticae egg production was seen. However, there was no significant effect on egg production and mortality of T. urticae in the three-way or two-way interactions of sulfur, powdery mildew and predatory mite. There was no significant effect of sulfur on mortality of P. persimilis, and sulfur did not seem to affect the efficiency of this predatory mite. Powdery mildew did not affect T. urticae probably because the mildew was not well developed due to inoculation at the same time as the mites were added. In another experiment, however, mites were released on leaf disks that had well developed powdery mildew, and here a negative effect of the mildew on T. urticae egg production was clearly seen.
Forfattere
Atle Wibe Anna-Karin Borg-Karlson Jerry Cross Lene SigsgaardSammendrag
One of the major pests on cultivated strawberry in northern part of Europe is the strawberry blossom weevil, Anthonomus rubi. The weevils deposit eggs in the flower buds before it sever the buds from their stalks. This may lead to a direct loss of crop of more than 50%. To develop effective plant protection method against A. rubi funnel traps baited with the sex aggregation pheromone and plant volatiles were used for trapping weevils in the fields. The sex pheromone blend used in the study was a mixture of Grandlure I, Grandlure II and Lavendulol (ratio 1:4:1). Plant volatiles emitted by the strawberry plants were collected using SPME and identified by GC/MS. These chemical analyses identified several compounds present in different quantities. The sex pheromone blend and selected plant volatiles were tested in fields either separately or in different mixtures. The field trials were carried out during a three year period where the last year aimed to optimise the mixture used in the previous years by adding more test compounds and testing the most potent compound at different concentrations. To improve insect catch rates modified traps were also tested. The study sites were in Norway, Denmark and in the UK. General high catch rates were achieved at three different study sites in Norway due to high weevil density. The results from these fields, supported by the results from the fields with lower catch rates, were in accordance with each other. The main finding was that traps baited with some identified plant volatile compounds and the sex pheromone blend increased the catch rates compared to traps bated with single a plant compound or the sex pheromone blend alone. The results show also that the concentration of the plant volatiles relative to the pheromone concentration is important for attracting weevils to the traps. This study has shown that it is important to bait insect traps with both sex aggregation pheromones and plant volatiles at the correct level to achieve significant catch rates of A. rubi. Hopefully, the results will generate knowledge important for developing new plant protection method for strawberry without using insecticides.
Forfattere
Trygve S. Aamlid Line Rosef Per Anker Pedersen Anne A. SteensohnSammendrag
A factorial trial comparing various subsoils (mineral, organic, and 50/50 (v/v) mineral/organic mixture), no liming vs. liming (1100 kg CaO/ha), and no sowing vs. sowing of an imported seed mixture or a mixture based on Norwegian mountain ecotypes, was established on 9 July 2008 in Bitdalen, Telemark. The establishment of vegetation from seed was faster on the organic and mixed soils than on the mineral soil. Although the initial pH(H2O) was higher in the mineral soil (5.8) than in the organic and mixed soils (4.9-5.0), the greatest relative effect of liming on plant cover was found on the former soil type. The imported seed mixture, mostly consisting of Danish and Dutch varieties, resulted in faster establishment than the seed mixture consisting of Norwegian ecotypes. One year later, the difference in ground cover was less conspicuous, but total above-ground plant biomass was almost three times higher after use of the imported seed mixture (77 vs. 29 g DM/m2). The imported seed also had a much greener appearance than the Norwegian ecotypes and the local vegetation. On average for soil types and liming treatments, the ground cover on unseeded plots increased from 1% six weeks after sowing to 24% after fourteen months; this cover mostly consisted of Agrostis spp. and mosses. It is concluded (1) that soil organic matter is a valuable resource that should be well preserved during restoration projects; (2) that the use of imported / unadapted seed mixtures must be avoided; and (3) that the use of a well adapted seed mixture from alpine ecotypes may be a good alternative to leaving the ground unseeded especially where there is a poor seed bank, where there is a need for rapid development of vegetation cover, or where a cover of grasses is wanted for functional reasons.
Forfattere
Sven-Roar Odenmarck Agnethe Christiansen Hans Ragnar Norli Børge HolenSammendrag
The LC-MS/MS multi-method was initially set up by Agilent Technologies and further developed in our laboratory by introducing programmed injection and dynamic MRM (dMRM).The instrument used is an Agilent 6410B with a 1200 LC and MassHunter software. The method covers 180 compounds with two MRM transitions for each, which gives acceptable identification of the pesticides in one run. QuEChERS extraction is used for sample preparation, and the same extract is directly analysed on both GC-MS and LC-MS/MS. The method is applied on all samples in the Norwegian monitoring programme for pesticide residues in fruit and vegetables; about 1500 samples per year. Direct injection of the acetonitrile extract gave insufficient retention and peak-splitting for the polar pesticides due to the high solvent strength. To avoid the time consuming process of either dilution of the sample extract or changing the sample solvent before injection, programmed injection was tested. Different techniques and parameters for programmed injection were tested and the results compared to samples with various solvent compositions. The best result was obtained using programmed injection by mixing the sample with water in proportion 1 to 10 online. Using the MS/MS with dMRM gives several advantages compared to MRM with compounds in time segments. In dMRM each compound has its own time window, and the time windows can overlap. This makes it easier to set up the method, to add new compounds and to administrate the routine analyses. The MS works more efficiently by measuring only a narrow time window for each compound. This makes it easier to increase the number of measuring points per peak if necessary, and to expand the scope of the method. More than 20 new compounds in the EU coordinated programme 2010 were recently added to the method. Flagging of results outside predetermined limits and custom-made reports make processing and interpretation of data easy, fast and reliable. Results from control samples and validation can easily be transferred to Excel for further calculation using script reporting template.
Forfattere
Ricardo Holgado Christer MagnussonSammendrag
In 1955 the potato cyst nematode (PCN) was recorded for the first time in Norway. This detection resulted in extensive surveys and measures were implemented based on the statutory regulation of 1916. The first statutory regulation for PCN was put in power in 1956, and later amended in several occasions. These regulations prohibit the introduction and spread of PCN with soil and plant materials. Early control strategies included the use of chemical fumigants and resistant potato cultivars in infested fields, and surveys detected new infestations which were placed under quarantine regulations. The recognition of G. rostochiensis and G. pallida, their pathotypes enabled a more precise use of resistant cultivars. Commercial chemical fumigants, organophosphates or carbamate nematicides have not been used in Norway since the early 1970s. Today, non-virulent G. rostochiensis is managed by crop rotation, while infestations by G. pallida or virulent G. rostochiensis results in at least 40-years ban for growing potato. Most Norwegian potato cultivars have the resistance genes, Gro-1 (H1) from Solanum tuberosum ssp. andigena. During the preceding decades great emphasis has been placed on documenting freedom from PCN in the production of certified seed potatoes, certified seed potato are used in combination with crop rotations using non-host crops, alternating susceptible and resistant cultivars. These are important control measures, but not easy to implement in Norway due to restricted acreage suitable for long rotations. The safe use of resistant potato cultivars requires a better knowledge on the presence of species and pathotypes in potato fields. In order to improve our information of the occurrence of PCN a new national survey program for the principal potato districts has started. These surveys will complemented by information generated from a new research project dealing with: studies of the virulence of selected PCN populations, decline rates of nematode field population densities and infection potential over time of populations from fields placed under quarantine regulations. studies on the occurrence and pathogenicity of microbial antagonistic parasitic on PCN, and their potential of future management of PCN, the safe use of early potato cultivars as a practical control method, and the potential for using Solanum sisymbriifolium as a trap crop, distinguish the degree of resistance of selected potato varieties available on the Norwegian market, and initial studies of the PCN-Potato-Pathosystem. These expected results of this project possibly will improve the management of PCN, and may alleviate present regulatory restrictions.
Forfattere
Ketil HaarstadSammendrag
A literature review shows that more than 500 organic and metallic compounds have been reported occurring in wetlands, and also that wetlands are suitable for removing pollutants. There are, however, obvious pitfalls for treatment wetlands, the most important being the maintenance of the hydraulic capacity and controlling the detention time. Treatment wetlands should have an adapted design to target specific compounds. Aquatic plants and soils are suitable for wastewater treatment because they have a high capacity of removing nutrients and other substances through uptake, sorption and microbiological degradation. The heavy metals Cd, Cu, Fe, Ni and Pb were found to exceed limit values in water. Also these studies revealed high values of phenol and SO4. No samples showed concentrations in sediments exceeding limit values, but fish samples showed concentrations of Hg exceeding the limit for fish sold in the EU. The main route of heavy metal uptake in aquatic plants was through the roots in the case of emergent and surface floating plants, whereas in submerged plants roots as well as leaves take part in removing heavy metals and nutrients. Submerged rooted plants have potential from water as well as sediments, where as rootless plants extracted metals rapidly only from water. Caution is due about the use of SSF CWs for the treatment of metal-contaminated industrial wastewater as metals are shifted to another environmental compartment and moreover stable redox conditions are required to ensure long-term efficiency. Mercury is one of the most toxic heavy metals and since wetlands have been shown to be a source of methylmercury. Methyl Hg concentrations are typically approximately 15% of Hgt. In wetland water samples, PAH, bisphenol A, BTEX, hydrocarbons including diesel range organics, glycol, DDT, PCB, cyanide, benzene, chlorophenols and formaldehyde were found to exceed limit values. In sediments only PAH and PCB were found exceeding limit values. In the water phase the pesticides found above limit values were atrazine, simazine, terbutylazine, metolachlor, mecoprop, endosulfan, chlorfenvinphos and diuron. There are few listings of these compounds in the commonly used water quality limit values, except for some well-known endocrine disrupters such as nonylphenol, phtalates etc. The performance of extensive household wastewater treatment systems of removing pharmaceuticals and personal care products (PPCPs) are similar to that obtained in conventional activated sludge wastewater treatment plants
Sammendrag
VKMs Panel on Plant Health gives the following main conclusions of the pest risk assessment: 1) The pest of concern is the oomycete Phytohthora fragariae Hickman. The PRA area is Norway. P. fragariae is present in at least five limited regions of the PRA area. These regions are located in the counties of i) Hedmark, ii) Aust-Agder and Vest-Agder, iii) Hordaland and Rogaland, iv) Vestfold, and v) Møre og Romsdal. It is probable that the pathogen is present at some places of production without having been detected yet. The pathogen is regulated as a quarantine pest in the PRA area. 2) With the current import regulations there is a medium probability of introduction of P. fragariae through import of infected Rubus plants for planting and a low probability of introduction through import of other consignments. However, there is little updated information available on the presence of the pathogen in different production systems, and there is only very limited evidence that the pathogen can spread by other means than strawberry plants. The level of uncertainty is therefore high. 3) Without the current import regulations there would be a very high probability of introduction through the import of non-certified strawberry plants. The level of uncertainty of this assessment is low. The probability of introduction through import of certified strawberry plants is considered low, but without detailed information on the presence/absence of the pathogen in such material the level of uncertainty is high. 4) With the current pest management procedures the probability of spread within the PRA area is medium for raspberry plants and machinery, other farm implements, footwear and animals. The probability of spread through other pathways ranges from low (legally traded, non-certified strawberry plants, seed potatoes, surface water, waterways and irrigation systems) to very low (remaining pathways). The level of uncertainty is low for certified strawberry plants and medium for legally traded, non-certified strawberry plants. Due to limited knowledge on the spread and survival of the pathogen, the level of uncertainty is high for all other pathways. 5) Without the current pest management procedures the probability of spread with strawberry plants within the PRA area would be very high. The probability of spread with raspberry plants would be high and the probability of spread with seed potatoes, machinery, other farm implements, footwear, animals, surface water, waterways and irrigation systems would be medium. The probability of spread through other pathways would range from low to very low. The level of uncertainty is low for strawberry plants, but due to limited knowledge on the spread and survival of the pathogen, the level of uncertainty is generally high for all other pathways. 6) All strawberry-growing areas in the whole PRA area are considered endangered areas.