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.
2011
Abstract
odronia canker (Godronia cassandrae f. sp. vaccinii) is a severe disease in young plantings of highbush blueberry (Vaccinium corymbosum L.) in Norway. In Europe, only the imperfect stage (Topospora myrtillii) has been reported, and thus conidia produced in pycnidia are assumed to be important for dissemination of the fungus. The seasonal pattern of production of conidia was investigated in a commercial planting of ‘Jersey" in 1998 and a research planting of ‘Bluecrop" in 1998 to 2000. The disease became apparent in March on shoots infected the preceding growing season, and lesions started to form pycnidia containing conidia in April. Samples of stems with distinct lesions of Godronia canker were collected from the bushes every two to three weeks from early spring to autumn. Stem pieces with lesions were shaken in water to release conidia from the pycnidia, and the numbers of conidia were determined by microscopy. Conidia were present throughout the growing season, but the highest numbers occurred during May, with 106 to more than 107 conidia per lesion. The numbers generally decreased during July to 20 % or less of that found in May, and decreased further during September to around 4 %. Ability to germinate remained high throughout the period conidia were trapped, from April to November/December. Options to manage the disease are discussed.
Authors
Mekjell Meland Lars Sekse Clive KaiserAbstract
‘Summerred" apples (Malus domestica) Borkh are highly susceptible to biennial bearing if not properly thinned. This results in erratic yields and also affects fruit quality adversely. Between 2003 and 2005 ‘Summered"/‘M9" trees were treated with ethephon at concentrations of 250, 375 and 500 mL·L-1 when most king flowers opened (ca. 20% bloom) or at concentrations of 500, 625 and 750 mL·L-1 when the average fruitlet size was 10 mm in diameter. The experimental design was a completely randomised block design with 6 whole tree plots per replication. Trees were sprayed to the point of run-off with a hand applicator only when temperatures exceeded 15ºC. Within two weeks after the second application fruit set was reduced linearly with increasing concentrations of ethephon to less than 1 fruitlet per cluster at the highest concentrations used. Most thinning treatments reduced fruit set significantly compared to unthinned trees. Fruit numbers per tree decreased significantly with increasing ethephon concentrations, and the highest concentrations of ethephon applied during bloom or when the average fruitlet size was 10 mm in diameter resulted in over-thinning. Yield results confirmed the fruit set response where yield reductions were significant at highest concentrations of ethephon (2.1 kg·tree-1) compared to hand-thinned trees (7.3 kg·tree-1) in 2005. All thinning treatments resulted in higher percentage of fruits larger than 60 mm diameter average fruit size compared to unthinned control fruit. Thinning resulted in significantly higher soluble solid contents, and this was especially so for hand-thinned trees. Other fruit quality parameters like yellow/green background color did not show a clear response to thinning. Fruit firmness, however, decreased slightly in all ethephon treated trees whereas return bloom was improved on all thinned trees. It is recommended that ethephon be applied at a rate of 375 mL·L-1 when king flowers open or at a rate of 625 mL·L-1 when the average fruitlet size is 10 mm in diameter. These treatments thin ‘Summerred" apples to a target of about 5 fruits·cm-2 per trunk cross sectional area or 50-70 fruits·100 flower clusters-1 without impacting fruit quality, yield or return bloom the following year.
Authors
Helja-Sisko Helmisaari Kjersti Holt Hanssen Staffan Jacobson Mikko Kukkola Jukka Luiro Anna Saarsalmi Pekka Tamminen Bjørn TveiteAbstract
The aim of this study was to determine the effect of whole-tree harvesting (WTH) on the growth of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) as compared to conventional stem harvesting (CH) over 10 and 20 years. Compensatory (WTH+ CoF) and normal nitrogen-based (CH + F or WTH+ F) fertilisation were also studied. A series of 22 field experiments were established during 1977–1987, representing a range of site types and climatic conditions in Finland, Norway and Sweden. The treatments were performed at the time of establishment and were repeated after 10–13 years at 11 experimental sites. Seven experiments were followed for 25 years. Volume increment was on average significantly lower after WTH than after CH in both 10-year periods in the spruce stands. In the pine stands thinned only once, the WTH induced growth reduction was significant during the second 10-year period, indicating a long-term response. Volume increment of pine stands was 4 and 8% and that of spruce stands 5 and 13% lower on the WTH plots than on CH during the first and the second 10-year period, respectively. For the second 10- year period the relative volume increment of the whole-tree harvested plots tended to be negatively correlated with the amount of logging residue. Accordingly, the relative volume increment decreased more, the more logging residue was harvested, stressing the importance of developing methods for leaving the nutrient-rich needles on site. If nutrient (N, P, K) losses with the removed logging residues were compensated with fertiliser (WTH+ CoF), the volume increment was equal to that in the CH plots. Nitrogen (150–180 kg ha−1) or N+ P fertilisation increased tree growth in all experiments except in one very productive spruce stand. Pine stands fertilised only once had a normal positive growth response during the first 10-year period, on average 13m3 ha−1, followed by a negative response of 5m3 ha−1 during the second 10-year period. The fertilisation effect of WTH+ F and WTH+ CoF on basal area increment was both smaller and shorter than with CH+ F.
Abstract
The aim of this study was to use energy-dispersive X-ray spectroscopy (EDX) to localize chitosan in the cell wall of chitosan-impregnated Scots pine. It was of interest to investigate the concentration of chitosan in wood to gain further knowledge and understanding of the distribution of chitosan in the wooden matrix. After deacetylation, chitosan was re-acetylated with chloroacetic anhydride to achieve a covalent bonding of chloride to the chitosan polymer. Chloride-labelled chitosan was measured by EDX using a scanning electron microscope and described as chloride intensity. Analysis of free chloride anions was performed by dialysis and inductively coupled plasma atomic emission spectroscopy. There was a significant correlation between the molecular weight of chitosan and the intensity of covalentbonded chloride to the chitosan polymer. High molecular weight chitosan showed a better interaction with the cell wall structure than low molecular chitosan.
Abstract
The centennial volume of this journal provides a fitting time to stop and reflect. Do we know where we are heading? Are we progressing in the right direction? Having studied landscape change for some years, we have seen the tremendous power of engagement that can be found in landscapes. Landscape is a theme that most people easily relate to. At the same time, landscape research has provided many appropriate tools for documenting landscape change and the effects of change. Yet in spite of public engagement and scientific knowledge, we still find many examples of negative landscape developments. In this paper we reflect on the applications of landscape research and the issue of communicating scientific findings to policy, management, landowners and the general public. Do we need a greater focus on communication to achieve sustainable landscape development?
Abstract
Frequent bark beetle outbreaks cause biome-scale impacts in boreal and temperate forests worldwide. Despite frequent interceptions at ports of entry, the most aggressive bark beetle species of Ips and Dendroctonus in North America and Eurasia have failed to establish outside their original home continents. Our experiments showed that Ips typographus can breed in six North American spruce species: Engelmann spruce, white spruce¸ Sitka spruce, Lutz spruce, black spruce and red spruce. This suggests that differences between the Eurasian historical host and North American spruce species are not an insurmountable barrier to establishment of this tree-killing species in North America. However, slightly diminished quality of offspring beetles emerged from the North American spruces could reduce the chance of establishment through an Allee effect. The probabilistic nature of invasion dynamics suggests that successful establishments can occur when the import practice allows frequent arrivals of non-indigenous bark beetles (increased propagule load). Model simulations of hypothetical interactions of Dendroctonus rufipennis and I. typographus indicated that inter-species facilitations could result in more frequent and severe outbreaks than those caused by I. typographus alone. The potential effects of such new dynamics on coniferous ecosystems may be dramatic and extensive, including major shifts in forest structure and species composition, increased carbon emissions and stream flow, direct and indirect impacts on wildlife and invertebrate communities, and loss of biodiversity.
Abstract
We examine the origins and outcome of entrepreneurship on the basis of exceptionally comprehensive Norwegian matched worker–firm–owner data. In contrast to most existing studies, our notion of entrepreneurship not only comprises self-employment, but also employment in partly self-owned limited liability companies. Based on this extended entrepreneurship concept, we find that entrepreneurship tends to be profitable. It also raises income variability, but the most successful quartile gains much more than the least successful quartile loses. Key determinants of the decision to become an entrepreneur are occupational qualifications, family resources, gender, and work environments. Individual unemployment encourages, while aggregate unemployment discourages, entrepreneurship.
Authors
Ole Tobias Rannestad May Sæthre Amon P. MaerereAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Bjørn Kløve Pertti Ala-Aho Guillaume Bertrand Zuzana Boukalova Ali Ertürk Nico Goldscheider Jari Ilmonen Nusret Karakaya Hans Kupfersberger Jens Kværner Angela Lundberg Marta Mileusnic Agnieszka Moszczynska Timo Muotka Elena Preda Pekka Rossi Dmytro Siergieiev Josef Simek Przemyslaw Wachniew Vadineanu Angheluta Anders WiderlundAbstract
No abstract has been registered