Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2008
Authors
Bjørn Molteberg Trygve S. Aamlid Gudni Thorvaldsson Anders Hammarlund Frank Enger Jan Tangsveen Trond Olav Pettersen Daniel NordAbstract
This report gives the summary results of the sowing year 2007 and first green year 2008 from testing of turfgrass varieties for use on Scandinavian golf greens. The total project period is 2007-2010.
Abstract
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.
Authors
Hege HovdAbstract
No abstract has been registered
Abstract
No abstract has been registered
Lecture – Farming in protected landscapes
Wendy Fjellstad, Klaus Mittenzwei, Wenche E. Dramstad, ...
Abstract
Achieving multifunctionality on a parcel of land, or in a landscape as a whole, requires a delicate balance between the different functions. This is particularly so when one of the desired functions is agricultural production. This paper examines the special challenges involved when cultural landscapes are protected by law. Norwegian `Landscape Protection Areas` are intended to preserve the landscape character of special landscapes. Ideally these landscapes should preserve ecological functions, whilst at the same time allowing for recreation and tourism, and the economic returns to ensure continued use of the landscape in the future. Balancing these functions is fraught with difficulties. The former agricultural systems that shaped these cultural landscapes may no longer be viable from the perspective of food production, and biodiversity is notoriously bad at paying for itself. Are the farmers that own the land willing to take on new roles as landscape managers rather than food producers? And who will pay for this? We present results of a questionnaire to farmers that own or manage farmland in Landscape Protection Areas. Of the 893 respondents, almost a quarter claimed that their farm business had been negatively affected by landscape protection. Niche products or alternative income possibilities had not been realised. We found a generally negative attitude towards municipal authorities and 24 % of respondents were strongly against the establishment of new Landscape Protection Areas, even if the State paid compensation for their economic loss. Based on results of the study we suggest that major improvements to the protection system could be made simply by improving communication between management authorities and farmers and involving farmers in making management plans.
Authors
Lukas Gudmundsson Holger LangeAbstract
Many time series analysis methods depend on equally spaced observations with no data point missing. If this condition is met, powerful techniques are available that identify temporal structures such as trends, periodic phenomena or nonlinear dynamics. Unfortunately, most observations of natural systems, in particular over longer periods of time such as decades, are prone to sampling errors leading to missing points in the observations. Singular System Analysis (SSA) is a powerful tool to extract the dynamics contained in time series at arbitrary temporal scales. In its original formulation, however, SSA relies as well on data without missing values. Recently several extensions to SSA have been proposed which are designed to fill the gaps, exploiting the dynamics contained in the sampled parts of the series to estimate the structure of the signal at the position of missing values. SSA consists of two steps: Decomposition and reconstruction. For the decomposition the time series under investigation is embedded into a trajectory matrix and decomposed with singular value decomposition. The reconstruction (of selected components) of the time series employs the left and right singular values to obtain additive components of the time series. In the original variant of SSA both steps are dependent on gap free data sets. In order to evaluate the power of SSA for time series with missing values we simulate 1000 series of different processes - ARMA(2,3) and red noise contaminated sine waves. Several gap–schemes (continuous, periodic, and uniformly distributed) are used to create time series with up to 50% (artificially) missing values. SSA is applied on all surrogate series. The decomposition as well as the reconstruction is compared systematically to the gap free benchmark. In addition we evaluate the ability of SSA to capture periodic phenomena in the presence of missing values and whether periodical gaps lead to the identification of spurious periods. We demonstrate that SSA successfully reproduces the signal part of time series (i.e. components with large eigenvalues) for up to 30% missing values. For less significant components with higher rank numbers, the presence of gaps is increasingly deleterious. A number of distributed smaller gaps, a situation most likely to occur in observations, spoils the analysis to a much lesser degree than a single large gap. Thus, these new variants of SSA substantially enlarge the set of observational time series amenable to the analysis, and allows for obtaining precise estimates of the signal at the position of missing data points.
Abstract
Many time series analysis methods depend on equally spaced observations with no data point missing. If this condition is met, powerful techniques are available that identify temporal structures such as trends or periodic phenomena or nonlinear dynamics. Unfortunately, most of observations of natural systems, in particular over longer periods of time such as decades, are prone to sampling errors leading to missing points in the observations. Singular System Analysis (SSA) is a powerful tool to extract the dynamics contained in time series at arbitrary temporal scales...
Abstract
A field fertilizer trial planted in late August was used to study effects of fertilizer timing and application method on flowering and ripening in strawberry cv. Korona. In treatment 1 (T1), fertilization in August prior to planting was followed by fertigation with low nutrient rate from May to August in the first harvest year. In treatment 2 (T2) all nutrients were applied as nutrient solution from May to August the first harvest year. By August in the first harvest year, the total amount of fertilizer applied was similar for both treatments (80 kg N ha(-1)). Equal amounts of water were also applied in both treatments. In the second harvest year, all the fertilizer was applied using fertigation from May to August. Both treatments were given the same fertilizer rate (80 kg N ha(-1)) to study after-effects of T1 and T2. In the first harvest year, preplant fertilized plants flowered earlier and required a higher number of days and day-degrees from anthesis to berry ripening than did T2 plants which were not fertilized until spring the first harvest year. Significant differences were found in yield but not in the number of berries, as berry size was significantly higher in T1. No significant differences were found between fertilizer treatments in the second harvest year, although T2 tended to yield the maximum number of berries later in the season than T1.
Abstract
The environmental control of flowering in five populations of Fragaria virginiana ssp. glauca and three populations of F virginiana ssp. virginiana (henceforth referred to as F virginiana), obtained as seed from the National Plant Germplasm Repository, Corvallis, OR, USA, has been studied under controlled environment conditions. Except for the F virginiana ssp. glauca population PI 551648 from the Wasatch Mountains in Utah, which was truly day-neutral across a 9 degrees - 27 degrees C temperature range, all the other populations of both sub-species behaved as quantitative (facultative) short-day (SD) plants with earlier and more abundant flowering under SD than under long-day (LD) conditions. Flowering of the remaining F virginiana ssp. glauca populations was governed by a significant interaction of photoperiod and temperature. The SD dependence for flowering increased with increasing temperature from 9 degrees C to 27 degrees C. The optimum temperature for the SD flowering response was 15 degrees - 21 degrees C. While SD promotion of flowering was more pronounced in the F virginiana populations, temperature had no significant main effect on flowering in this sub-species, demonstrating a wide temperature tolerance for flowering. Vigorous runner formation was observed in all populations, in both SD and LD, with a highly significant advancement effect of increasing temperature. The flowering and runnering responses of these E virginiana populations are discussed in relation to their putative paternity of perpetual-flowering F. X ananassa cultivars. It is concluded that, with the complex inheritance in these octoploid plants, the flowering responses of the populations studied here are not reflected in the LD flowering response of cultivated everbearing strawberries.
Academic – Focused flow in the unsaturated zone after surface ponding of snowmelt
Nils-Otto Kitterød
Authors
Nils-Otto KitterødAbstract
No abstract has been registered