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.
2007
Abstract
Floral induction and development requirements of a range of latitudinal and altitudinal Norwegian populations of the wild strawberry Fragaria vesca L. have been studied in controlled environments. Rooted runner plants were exposed to a range of photoperiods and temperatures for 5 weeks for floral induction and then transferred to long day (LD) at 20 degrees C for flower development. A pronounced interaction of temperature and photoperiod was shown in the control of flowering. At 9 degrees C, flowers were initiated in both short day (SD) and LD conditions, at 15 and 18 degrees C in SD only, whereas no initiation took place at 21 degrees C regardless of daylength conditions. The critical photoperiod for SD floral induction was about 16 h and 14 h at 15 and 18 degrees C, respectively, the induction being incomplete at 18 degrees C. The optimal condition for floral induction was SD at 15 degrees C. A minimum of 4 weeks of exposure to such optimal conditions was required. Although the populations varied significantly in their flowering performance, no clinal relationship was present between latitude of origin and critical photoperiod. Flower development of SD-induced plants was only marginally advanced by LD conditions, while inflorescence elongation and runnering were strongly enhanced by LD at this stage. The main shift in these responses took place at photoperiods between 16 and 17 h. Unlike all other populations studied, a high-latitude population from 70 degrees N ('Alta') had an obligatory vernalization requirement. Although flowering and fruiting in its native Subarctic environment and after overwintering in the field in south Norway, this population did not flower in the laboratory in the absence of vernalization, even with 10 or 15 weeks of exposure to SD at 9 degrees C. Flowering performance in the field likewise indicated a vernalization requirement of this high-latitude population.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Ievina Sturite Trond Maukon Henriksen Tor Arvid BrelandAbstract
Conclusions The short lifespan and poor over-wintering of leaves showed their potential importance as a nitrogen source in the soil-plant ecosystem but also their potential contribution to the risk of off-season N losses.
Authors
Svein Solberg Erik NæssetAbstract
The aim of this article is to present a concept of using airborne laser scanning (LIDAR), with one scan only, to map defoliation as a forest health variable. The idea is to apply two independent algorithms on the LIDAR data set, to produce both actual and expected leaf area index (LAI) values for every cell in a grid over the area. LAI is estimated based on laser pulse penetration through the canopy layer, and expected LAI values are derived from stand density based on position and height of single trees as obtained from a single-tree segmentation algorithm. The results are preliminary findings from four ongoing and related studies. In the first study repeated laser scans had close to equal extinction coefficients for LAI estimation although the instruments and flight specifications were different. In the second study, based on the findings in the first we derived normal LAI values from extisting and large scale data sets with LIDAR and field data. The main independent variable was stand density, defined as the ratio between mean tree height and mean distance between the trees. The ratio between LAI and stand density was around 0.5, and this is a preliminary standard for a healthy pine forest. In a third study the woody area fraction of LAI was estimated from 14 total harvested trees, and turned out to be slightly below 50% for a healthy pine tree, which means that a totally defoliated pine forest would have an LAI/stand density ratio around 0.2. In the fourth study, these LAI standard values were confirmed with LIDAR data from a severe insect defoliation event in Norway 2005. In conclusion, the present preliminary results demonstrate a potential for application of airborne laser scanning for monitoring or mapping of defoliation as a forest health variable.
Authors
Derek Stewart Gordon J. McDougall Julie Sungurtas Susan Verall Julie Graham Inger MartinussenAbstract
Plant polyphenolics continue to be the focus of attention with regard to their putative impact on human health. An increasing and ageing human population means that the focus on nutrition and nutritional enhancement or optimisation of our foodstuffs is paramount. Using the raspberry as a model, we have shown how modern metabolic profiling approaches can be used to identify the changes in the level of beneficial polyphenolics in fruit breeding segregating populations and how the level of these components is determined by genetic and/or environmental control. Interestingly, the vitamin C content appeared to be significantly influenced by environment (growth conditions) whilst the content of the polyphenols such as cyanidin, pelargonidin and quercetin glycosides appeared much more tightly regulated, suggesting a rigorous genetic control. Preliminary metabolic profiling showed that the fruit polyphenolic profiles divided into two gross groups segregating on the basis of relative levels of cyanidin-3-sophoroside and cyanidin-3-rutinoside, compounds implicated as conferring human health benefits.
Abstract
Furfurylated wood has shown to have promising properties for a wood modification agent during the last years. In this paper, an alternative curing method for furfuryl alcohol modified pine sapwood by means of microwave radiation was investigated. Different process parameters of microwave treatment such as output power, exposure time to microwave radiation, initial wood moisture content and evaporation during treatment, were tested. The weight percent gain of pine wood samples due to polymerised furfuryl alcohol was investigated by means of thermo gravimetric analysis. Leaching of furfuryl treated and differently cured samples gave information about the degree of fixation. No distinct influence of initial moisture content could be stated. A slight tendency of improving the degree of fixation by increasing the consumption energy of wood samples due to microwave energy was found. Changing the evaporation ability of samples during microwave treatment by using plastic foil had no distinct influence. Fixation of furfuryl alcohol could be improved by microwave treatment, and a degree of fixation above 90 % was calculated. However, the fixation was lower than in oven cured samples.
Abstract
No abstract has been registered
Authors
Holger LangeAbstract
The net ecosystem productivity (NEP) of a sequence of threemonoaged Norway spruce stands located in southeast Norway is modelled using the biogeochemical model Biome-BGC. For calibration, we use estimated biomass stocks at the plot level and Leaf Area Index measurements. The model is run for 30 years of historical temperature measurements as well as for a regional climate scenario. It is shown that under current conditions, NEP develops from negative values for a young stand (30 years) to clearly positive for a middleaged (60 years) to slightly negative again for a very old and decaying stand (120 years). However, the old stand benefits substantially from the predicted increased temperatures in the climate scenario, rendering NEP positive again. For the 30 and 60 years stands, almost no change is predicted from Biome-BGC.
Authors
Peder GjerdrumAbstract
Moisture content in wood is a volatile feature, continuously changing under influence ofthe oscillating ambient climate. Unquestionably an essential quality trait for the timber,the MC and other drying quality aspects must be appropriate according to customerspecification at the time of delivery and final use.The objective of this presentation is to describe sorption relations in commercial timber boards for the period after kiln drying. Joint information from several semi-industrial experiments was used to establish MC prediction models for industrial applications. Kiln temperature was found to be of minor, however noticeable, significance to the equilibrium MC for timber dried in ordinary kilns operated below 100C.Spruce board samples of varying length from small, clear specimens up to commercial length boards were observed under varying climatic situations to analyse the nature of hysteresis. The hysteresis fades for smaller specimens and in dry settings. A differential (dynamic) model for MC sorption under steady-state climate at varying temperatures was estimated and analysed numerically.