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.
2010
Authors
May Sæthre Arnstein Staverløkk Eline HågvarAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Studying the winter survival of forage grasses under a changing climate requires models that can simulate the dynamics of soil conditions at low temperatures. We developed a simple model that simulates depth of snow cover, the lower frost boundary of the soil and the freezing of surface puddles. We calibrated the model against independent data from four locations in Norway, capturing climatic variation from south to north (Arctic) and from coastal to inland areas. We parameterized the model by means of Bayesian calibration, and identified the least important model parameters using the sensitivity analysis method of Morris. Verification of the model suggests that the results are reasonable. Because of the simple model structure, some overestimation occurs in snow and frost depth. Both the calibration and the sensitivity analysis suggested that the snow cover module could be simplified with respect to snowmelt and liquid water content. The soil frost module should be kept unchanged, whereas the surface ice module should be changed when more detailed topographical data become available, such as better estimates of the fraction of the land area where puddles may form.
Authors
Aruppillai Suthaparan Sissel Torre Arne Stensvand Maria Herrero Rolf Inge Pettersen David M. Gadoury Hans Ragnar GislerødAbstract
When rose plants bearing colonies of Podosphaera pannosa were placed in a wind tunnel, the number of conidia trapped was directly proportional to intensity of daylight-balanced (white) light from 5 to 150 mu mol m(-2) s(-1). Illumination of samples using blue (420 to 520 nm) light-emitting diodes (LEDs) increased the number of conidia trapped by a factor of approximately 2.7 over white light but germination of conidia under blue light was reduced by approximately 16.5% compared with conidia germination under white light. The number of conidia trapped under far-red (>685 nm) LEDs was approximately 4.7 times higher than in white light, and 13.3 times higher than under red (575 to 675 nm) LEDs, and germination was not induced compared with white light. When mildewed plants were exposed to cycles of 18 h of white light followed by 6 h of blue, red, far-red light, or darkness, light from the red LEDs reduced the number of conidia trapped by approximately 88% compared with darkness or far-red light. Interrupting the above dark period with 1 h of light from red LEDs also reduced the number of conidia trapped, while a 1-h period of light from far-red following the 1 h of light from red LEDs nullified the suppressive effect of red light. Our results indicate that brief exposure to red light during the dark interval may be as effective as continuous illumination in suppressing powdery mildew in greenhouse rose plant (Rosa x hybrida).
Abstract
The suitability of interferometric X-band radar for forest monitoring was investigated. Working in a spruce-dominated forest in southeast Norway, top height, mean height, stand density, stem volume, and biomass were related to space shuttle interferometric height above ground. A ground truth dataset was produced for each radar data pixel in the study area by combining a field inventory and automatic tree detection with airborne laser scanning data. Pixels were aggregated to forest stands. Interferometric height was strongly related to all of the five forest variables, and most strongly to top height with R-2 = 0.71 and RMSE = 13% at the pixel level and R-2 = 0.82 and RMSE = 5.6% at the stand level. Interferometric height was linearly related to stem volume and biomass up to 400 m(3)/ha and 200 t/ha, respectively, and RMSE was approximately 19% for both variables. These errors contain error components caused by the 3.5-year time lag between the radar acquisition and the laser scanning. It is concluded that interferometric X-band radar has potential for use in forest monitoring.
Authors
Wallace E. Huffman Sonya Huffman Kyrre Rickertsen Abebayehu TegeneAbstract
No abstract has been registered
Abstract
Development in surface mould growth on painted/unpainted wooden claddings and acting climatic factors were investigated over a period of 3 years. Eight wood substrates, including modified, preservative-treated and untreated wood, were tested in combination with three types of paint: (1) water-borne alkyd modified acrylic paint without fungicide; (2) solvent-borne alkyd paint without fungicide; and (3) ICP (internal comparison product). One set of samples was exposed unpainted. The samples were tested according to a modified version of EN 927-3. A logistic regression model was fitted to the data. The degree of mould growth varied with exposure time, coating typology, wood substrate, temperature and relative humidity. Exposure time and coating typology contributed most to the model. After 3 years of outdoor exposure unpainted panels and panels coated with solvent-borne paint without fungicide had more mould growth than panels coated with ICP and water-borne paint without fungicide. Unpainted oil/copper–organic preservative-treated claddings had higher resistance to mould growth than other unpainted wood substrates. Coated untreated pine and coated acetylated pine were more susceptible to mould growth than other coated wooden substrates.
Abstract
The effects of postflowering temperature on the fruit chemical composition of Glen Ample raspberries were studied under controlled environment conditions. The berry weight decreased significantly with increasing temperature (12, 18, and 24 degrees C) and with progress of the harvest period. Because the moisture content increased in parallel with the berry weight, the antioxidant capacity (AOC) and the concentration of a range of bioactive compounds decreased with decreasing temperature and progress of the harvest season when expressed on a fresh weight basis in the conventional way. Under those circumstances, dry weight units are therefore preferable. However, despite the dilution effect of large berries, the concentration of ascorbic acid (vitamin C) increased with decreasing temperature, even on a fresh weight basis. Berry AOC was closely correlated with total phenolic concentration (r = 0.958), predominantly anthocyanins and ellagitannins. While a total of 10 anthocyanins were detected, cyanidin-3-sophoroside and cyanidin-3-(2(G)-glucosylrutinoside)-rutinoside accounted for 73% of the total, the former decreasing and the latter increasing with increasing growth temperature. By far, the most prevalent ellagitannins were lambertianin C and sanguiin H-6, both of which increased significantly with increasing temperature. It is concluded that the growth temperature has significant and contrasting effects on the concentration of a range of potentially bioactive compounds in raspberry.
Authors
Håvard Steinshamn Mats Höglind Øystein Havrevoll Kristin Saarem Inger-Helene Lombnæs Geir Steinheim Asgeir SvendsenAbstract
The purpose of this study was to compare the effect of grazing on mountain (M) versus cultivated lowland pasture (C) on the performance and meat quality of suckling calves (Experiments 1 and 2). In addition, the effect of finishing on C after M on growth and meat quality was assessed (Experiment 2). Animals on C and M had on average similar live weight gain and carcass weight in the first experiment. However, the performance depended on year as gain and carcass weight was higher on C than on M in the first year and vice versa in the second year. In the second experiment the calves on M had lower gain and carcass weight than on C. Three weeks finishing on C after M compensated to some extent for the lower growth rate on M. Overall, the results indicate that mountain grazing may yield similar growth rates and slaughter weights as improved lowland pasture depending on year. There were only small effects of pasture type on carcass and meat quality traits like conformation, fatness, intramuscular fat and protein content, and fatty acid (FA) composition. The variation in FA composition could to a large extent be explained by difference in fatness with increase in monounsaturated and decrease in polyunsaturated FA with increasing intramuscular fat content, in turn varying between pasture type, experiment and year. There was a tendency that M led to higher proportion of C18:1n-9 and lower proportion of C18:1n-7 than C. which may be due to difference in milk and forage intake. Both pasture types resulted in meat with intramuscular fat with high nutritional value since the n-6/n-3 ratio was low. (C) 2010 Elsevier B.V. All rights reserved.
Abstract
The model FROSTOL simulates course of frost tolerance in winter wheat on a daily basis from sowing on as affected by soil temperature (2 cm), snow cover, phenological development, and a genotypic maximum level of frost tolerance (LT 50). A series of cultivar trials in Finland was used to evaluate the model's ability to estimate plant survival in natural field environments during winters with differing weather conditions. Recorded survival was compared with number of intersections between the curves of simulated LT50 and the soil temperature curve for each field. A cumulative stress level (CSL) was calculated based both on number of intersections and FROSTOL simulated stress levels. The correlation between CSL and field recordings was quite low. While the field trials characterize a general ability to stand various types of winter stress, FROSTOL estimates damage caused by the soil temperature regime only. However, FROSTOL simulations seemed to correspond reasonably well to field observations when low temperature was the eventual cause of damage.