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.
2002
Authors
Halvor SolheimAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Cleaning of containers to counteract infection that might cause root dieback should remove old, adhering media and roots that may harbour pathogens. This study investigated seedling growth and the number of viable fungal propagules retained on the container cavity walls as a result of different container cleaning treatments: washing with cold water (ca 8C) only, or in addition with a bath temperature of 60, 70, 80 or 95C for 30 seconds.More fungal propagules were isolated from containers washed in cold water, than from the other treatments. The most frequently isolated fungi were Paecilomyces sp. and Penicillium sp., which are well known saprophytes. Bacteria and yeast did not seem to be affected by the washing.Electron microscopy studies of container cavity walls revealed many organic particles and fungal spores on the walls of coldwashed containers. Among other fungal spores there were visible chains of Paecilomyces spp. spores.Containers that were washed at 80C had some organic debris attached to the cavity walls, but no spores were visible. In used and unwashed containers fungal spores, hyphae and organic debris were found on the container cavity walls. Containers in which the major part of the seedlings previously had suffered from root dieback might have contained a considerable amount of inoculum before washing.Almost 60% of the seedlings grown in unwashed containers had dead or very stunted root systems, whereas about 10% of the seedlings in cold washed containers suffered from severe root dieback. Additional warm water treatment further reduced the root dieback of this group of containers. In unwashed containers in which healthy seedlings had been grown, about 4% seedlings and after cold washing no seedlings with root dieback were observed.The cold washing procedure had a positive effect on seedling height, but there was no additional effect of the warm water treatment. We conclude that cold pressurised washing alone does not provide adequate control of root dieback and that an additional warm water bath of at least 60C is recommended.
2001
Abstract
Epiphytic lichen vegetation on birch stems was studied in the border areas between Norway and Russia. The area is heavily influenced by sulphur dioxide pollution emitted from Russian nickel smelters.Hypogymnia physodes and Melanelia olivacea were the two most abundant lichen species on birch stems in the investigated area. However, the coverage of H. physodes and M. olivacea was clearly reduced in parts of the investigated area. The lichen vegetation increased with increasing distance from the pollution source, i.e. from a lichen desert to normal background levels. A different pattern of occurrence of the two lichen species was observed.
Authors
Isabella BørjaAbstract
No abstract has been registered
Authors
Harald Kvaalen Erik Christiansen Øystein Johnsen Halvor SolheimAbstract
Genetic associations between initiation of embryogenic tissue (ET) and susceptibility to the phytopathogenic fungi Ceratocystis polonica (Siem.) C. Moreau and Heterobasidion annosum (Fr.) Bref. in Norway spruce have been studied by initiating ET from zygotic embryos of mature seeds collected from 19 clones tested for susceptibility to the pathogens in a clonal field trial.Initiation frequencies varied significantly among clones (families), ranging from 12 to 56%. The family variance component accounted for more than 40% of the total variance in initiation frequency of ET. The estimates of broad-sense heritability of fungus susceptibility of the clones ranged from 0.12 for length of phloem necrosis after low-density inoculation with H. annosum to 0.55 for blue-stained sapwood after mass inoculation with C. polonica.None of the susceptibility measures showed any phenotypic correlation with initiation of embryogenic tissue. Genetic correlations and their standard errors were estimated by bootstrapping. Two measures of fungal susceptibility correlated genetically with initiation of ET; estimated at 0.58 for lesion length after inoculation with C. polonica and 0.29 for H. annosum lesion length. A better measure of susceptibility, blue-stained sapwood following inoculation with C. polonica, was not correlated with initiation of ET.
Abstract
Air pollution induced changes in pine needle chemistry were observed at sample sites in the surroundings of the Pechenganikel smelter. Close to the smelter, elevated concentrations of Ni, Cu and S were found (Ni: 0.7-1 mmol/kg, CU: 0.4-0.5, and S 40-60 mmol/kg) Close to the pollution source needles were enriched in Ni and Cu by needle age. Correlation and principal component analyses show that changes in the element composition of pine needles depended on air pollution and on natural factors as well. The contribution from air pollution increased with needle age. Besides direct input of pollutants from atmosphere, soil contamination and nutritional disturbance contributed significantly to the observed changes.
Authors
Jenny Fäldt Halvor Solheim Bo Långström Anna-Karin Borg-KarlsonAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Toril Drabløs Eldhuset Berit Swensen Heleen A. de Wit Nina Davidsen Gro WollebækAbstract
No abstract has been registered