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.
2004
Authors
Erik Jautris Joner D. Hirmann O.J.H. Szolar D. Todorovic C. Leyval A.P. LoibnerAbstract
An experiment was conducted to distinguish priming effects from the effects of phytoremediation of a creosote-polluted soil. The concentration of 13 polycyclic aromatic hydrocarbons (PAHs), and their combined soil toxicity (using four bioassays), was determined on recently excavated, homogenized soil and on such soil subjected to a time-course phytoremediation experiment with lucerne.The results showed a high priming effect, with minor positive and synergistic effects of planting and fertilization on PAH degradation rates. At the end of the experiment, PAH degradation reached 86% of the initial 519 mg PAHs kg-1. Two of the four toxicity tests (bioluminescence inhibition and ostracod growth inhibition) corroborated the chemical data for residual PAHs, and indicated a significant reduction in soil toxicity.We conclude that priming effects can easily surpass treatment effects, and that an unintentional pre-incubation that ignores these effects can jeopardize the full quantitative assessment of in situ bioremediation of contaminated soil.
Abstract
Chitosan, a derivate of the natural amino polysaccharide chitin, has proven effective as a potential environmentally benign antimicrobial component. Few studies have focused on chitosan applied to wood against wood inhabiting and decaying fungi.In these screening studies several mycological experiments were performed to screen chitosan as a potential wood protecting agent. Growth studies on chitosan-amended media showed total inhibition of Poria placenta, Coriolus versicolor and Aspergillus niger using 1% w/v concentration.Chitosan with high average molecular weight (MW) was more efficient against mould and staining fungi than chitosan with low MW. Agar plate leaching tests showed only a small leaching effect using a 5% concentration on A. niger and P. placenta. Decay testing with P. placenta demonstrated efficacy using 5% and 2.5% concentrations in unleached samples. Leaching decreased the efficacy of chitosan and further investigations are needed to improve the fixation in wood.
Authors
Geir ØstrengAbstract
Artikkelen er basert på resultater fra et nordisk kurs i kalibrering av apparater for måling av CO2-frigivelse fra jord. Geir Østreng deltok på kurset med det apparatet som er brukt bl.a. i SIP Karbondynamikk i skogsjord 2000-2005, og han er medforfatter.
Authors
Inger Sundheim Fløistad Ketil KohmannAbstract
When spring frost occur on recently planted forest sites, severe damage may occur to the seedlings. The aim of the present study was to test how different levels of nutrient concentrations in the seedlings affected spring frost hardiness and time of bud break.Seedlings were grown in a greenhouse for one season and supplied with fertiliser containing 22, 43 and 72 mg N per litre respectively. The treatments resulted in needle nitrogen concentrations ranging from 0,9 to 1,8 % in the autumn.After winter storage at 0C, bud break was recorded on seedlings growing in greenhouse, outdoors and in growth chambers at 12C and at 17C. Freezing tests were performed on seedlings directly removed from winter storage and following one week growth in the greenhouse. Seedlings receiving fertiliser with 43 mg per litre had less freezing injury than the two other fertilisation treatments. The ealiest bud break occurred in seedlings receiving 72 mg per litre.
Abstract
Introduction: The objectives of the present study were to monitor H. annosum colonization rate (Hietala et al., 2003) and expression of host chitinases in clonal Norway spruce material with differing resistances. Transcript levels of three chitinases, representing classes I, II and IV, were monitored with real-time PCR.Material and MethodsInoculation experiment: Ramets of two 32 -year-old clones differing in resistance were employed as host material. Inoculation and wounding was performed. A rectangular strip containing phloem and cambium, with the inoculation site in the middle, was removed 3, 7 and 14 days after inoculation.Quantification of fungal colonizationMultiplex real-time PCR detection of host and pathogen DNA was performed (Hietala et al., 2003). Quantification of gene expression: Chitinase levels were monitored with Singleplex real-time PCR.Results and ConclusionsThe colonization profiles provided by the quantitative multiplex real-time PCR procedure (Hietala et al., 2003), when combined with spatial and temporal transcript profiling of 3 chitinases, provide a useful basis for identifying defense related genes, and for assessing their impact on pathogen colonization rates.Three days after inoculation, comparable colonization levels were observed in both clones in the area immediately adjacent to inoculation. Fourteen days after infection, pathogen colonization was restricted to the area immediately adjacent to the site of inoculation for the strong clone (589), but had progressed further into the host tissue in the weak (409) clone.Transcript levels of the class II and IV chitinases increased following wounding or inoculation, while the transcript level of the class I chitinase declined following these treatments. Transcript levels of the class II and class IV chitinases were higher in areas immediately adjacent to the inoculation site in 589 than in similar sites in 409 three days after inoculation, suggesting that the clones differ in the rate of chitinase-related signalperception.
Abstract
No abstract has been registered
Authors
Peder Gjerdrum Olav Albert HøibøAbstract
Automatic heartwood detection will improve the ability to produce timber of prescribed properties and increase sawmill revenues. In fresh crosscuts, evaporation cools the surface more in the moist sapwood than in the drier heartwood areas.In this semi-industrial investigation, infrared exposures of 180 pine sawlogs were analysed. An algorithm was established to determine the heartwood diameter fraction in a digital temperature profile through the crosscut. Top end heartwood diameter could then be computed automatically by multiplying top end diameter (measured by a traditional log scanner) with the heartwood fraction calculated from an infrared exposure taken at an arbitrary end.The temperature gradient between the heart- and sapwood indicated the accuracy of the method. A promising application would be to use the heartwood fraction to estimate mean annual ring width and other related wood properties, and to use the temperature gradient to indicate the log freshness.
Authors
Ken Olaf StoraunetAbstract
Number of years since death was estimated by dendrochronological cross-dating of 107 standing dead trees (snags) of Norway spruce [Picea abies (L.) Karst.] in a submountainous old-growth forest in south-central Norway. Snag characteristics (size, bark cover, branch order present and variables derived from tree-ring analyses) were used in stepwise linear regression procedures to identify variables that explained time since death.Number of branch orders present (where branches growing directly on the stem were branch order 1, branches growing on order 1 branches were order 2, and so on) explained two-thirds of the variation in time since death. Adding other significant variables, such as diameter, relative height of snags, percentage bark cover and average tree-ring width in the final years before death, increased model precision only moderately.The models were validated by the PRESS statistic, which showed that new observations were predicted fairly well with 65-69% of the variation explained.
Authors
Carl Gunnar Fossdal Øystein Johnsen Rüdiger Baumann Jørgen A. Mølmann Ola Gram Dæhlen Nina Elisabeth Nagy Tore SkrøppaAbstract
Research indicate that the female parents of Norway spruce adjust these timing events in their progeny according to the prevailing temperature conditions during seed development. Reproduction in a cold environment advances bud-set and cold acclimation in the autumn and dehardening and flushing in spring, whereas a warm reproductive environment delays these progeny traits by an unknown non-Mendelian mechanism. We have performed identical crosses in combination with timed temperature treatments during shorter and longer periods from female meiosis, pollen tube growth, syngamy and embryogenesis, tested the progenies for bud-set and frost hardiness, and concluded that the effect of temperature most likely is a response to accumulated heat during embryogenesis and seed maturation. Our first attempt to look for a molecular mechanism has revealed that transcription of PHYO, PHYP and PHYN and the class IV chitinase PaChi4 (using RealTime PCR) all show higher transcription levels in progenies born under cold conditions than their full-sibs born under warmer conditions. This result is consistent with preliminary findings that methylation of cytosine in total DNA is higher in progenies reproduce under warm conditions than their colder full-sib counterparts. If these observations are related to methylation, we may explain why progenies with a memory of a past time cold embryogenesis are more sensitive to short days than their full-sibs with a warmer embryonic history.
Authors
Lone Ross Gobakken Johan Mattsson Bjørn Jacobsen Fred G. EvansAbstract
No abstract has been registered