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
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Abstract
The causative agent of dieback on European ash (Fraxinus excelsior) was first described as Chalara fraxinea based on cultural morphology because no sexual stage of the fungus was known. Later, based on culturing of ascospores of a candidate teleomorph, morphological comparison and nuclear ribosomal internal transcribed spacer sequencing, the sexual stage of C. fraxinea was assigned as Hymenoscyphus albidus, a native and widespread species in Europe. Recently, the morphological species concept of H. albidus was shown to cover two species that cannot be separated from each other based on teleomorph characters, but which can be distinguished by several DNA markers. As a result, the strains causing ash dieback were reassigned as H. pseudoalbidus. The closely related H. albidus is presumably a non-pathogenic endophyte, but pathogenicity tests to confirm this hypothesis have not yet been performed. Genotyping of herbarium specimens has shown that H. pseudoalbidus was present in Switzerland for at least a decade prior to the epidemic outbreak in Europe. The origin of the ash dieback pathogen, and the general importance of correct pathogen identification to development of effective disease control, are discussed.
Abstract
This paper focuses on the improvement of a combined impregnation process (CIP, also known as the Royal process). This treatment combines the protective properties of a wood protection agent and the hydrophobic properties of a subsequent oil treatment in a wood product. Copper-based wood preservatives, which are traditionally used in CIP, are very effective but their long-term future use is questionable because of environmental concerns, especially the toxicity against water-living organisms. There is a need for new environmentally friendly wood preservative systems for a use in CIP. The substitutes for copper used in this study are natural polymers and organic biocides. The aim of this research is to describe the fixation effectiveness of the following compounds: Chitosan, Propiconazole, Wolmanit CX-8, Tannin, fire protection agent, Alginate. The scots pine sapwood samples (50´25´15) mm were impregnated and oil treated. The treated products were analysed for their preservative-and oil-retention. Preservative fixation time influence on oil treatment was tested. The treated samples were leached according to EN84. Water samples were analyzed for the amount of active ingredient.
Abstract
No abstract has been registered
Authors
Aparna Tiwari Adam Vivian-Smith Roeland E. Voorrips Myckel E.J. Habets Lin B. Xue Remko Offringa Ep HeuvelinkAbstract
Background Parthenocarpy is a desirable trait in Capsicum annuum production because it improves fruit quality and results in a more regular fruit set. Previously, we identified several C. annuum genotypes that already show a certain level of parthenocarpy, and the seedless fruits obtained from these genotypes often contain carpel-like structures. In the Arabidopsis bel1 mutant ovule integuments are transformed into carpels, and we therefore carefully studied ovule development in C. annuum and correlated aberrant ovule development and carpelloid transformation with parthenocarpic fruit set. Results We identified several additional C. annuum genotypes with a certain level of parthenocarpy, and confirmed a positive correlation between parthenocarpic potential and the development of carpelloid structures. Investigations into the source of these carpel-like structures showed that while the majority of the ovules in C. annuum gynoecia are unitegmic and anatropous, several abnormal ovules were observed, abundant at the top and base of the placenta, with altered integument growth. Abnormal ovule primordia arose from the placenta and most likely transformed into carpelloid structures in analogy to the Arabidopsis bel1 mutant. When pollination was present fruit weight was positively correlated with seed number, but in the absence of seeds, fruit weight proportionally increased with the carpelloid mass and number. Capsicum genotypes with high parthenocarpic potential always showed stronger carpelloid development. The parthenocarpic potential appeared to be controlled by a single recessive gene, but no variation in coding sequence was observed in a candidate gene CaARF8. Conclusions Our results suggest that in the absence of fertilization most C. annuum genotypes, have parthenocarpic potential and carpelloid growth, which can substitute developing seeds in promoting fruit development.
Abstract
In recent years the harmonization of methods in the frame of the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) operating under the UNECE Convention on Long-range Transboundary Air Pollution (CLRTAP) has been intensified. Among the C-actions of the FutMon project (LIFE07 ENV/D/000218; 2009-2010) the C1-Dep-22(SI) action was established with the goal to harmonize and develop the deposition monitoring procedures and sampling methods. The sampling equipment, spatial design of sampling plots and sampling frequency throughout Europe vary considerably. Therefore a step-by-step approach was made where the harmonized sampling equipment was developed and tested first. The selected collectors were installed at one observation plot of each participating country where measurements of throughfall and bulk deposition were run in parallel with the national collectors for a period of one year. To evaluate the agreement between methods, different statistical analyses were used including Altman-Bland plots, model II regression, and repeated measures ANOVA. Preliminary results from the “Intensive forest ecosystem monitoring plot” plot Brdo in NW Slovenia show a good agreement between national and harmonized bulk (both funnel-type) collectors, while comparison of throughfall measurements indicates systematic bias between harmonized (funnel-type) and national (gutter-type) collectors.
Abstract
Dieback of European ash (Fraxinus excelsior), caused by the ascomycete Hymenoscyphus pseudoalbidus (anamorph Chalara fraxinea), started around 1992 in Poland and has since then spread over large geographical areas. By November 2010, the disease had been recorded in 22 European countries. The gradual expansion and high intensity of the ash dieback epidemic in Europe may suggest that H. pseudoalbidus is an invasive alien organism. In Norway, ash dieback was first reported in spring 2008, and a survey in early summer of the same year revealed that the disease had spread over large parts of the southern and eastern regions of the country. The distance from the southernmost to the northernmost infected stands was, at that time, about 400 km. Some old necrotic lesions were also observed, indicating that the ash dieback pathogen is likely to have been present in Norway since at least 2006. In 2009, a spore sampler was installed in a diseased ash stand at Ås, South-Eastern Norway. Sampling started in late July and continued until late September. Large numbers of ascospores resembling those of H. pseudoalbidus were observed, with the maximum number of spores occurring from the end of July to mid-August. The deposition of ascospores occurred mainly between 6 and 8 a.m. Ascospores are most likely to be the primary source initiating host infections and responsible for the rapid recent spread of H. pseudoalbidus in Europe.
Authors
Sara Alva-Lizarraga Karen Refsgaard Thomas G. JohnsonAbstract
No abstract has been registered
Abstract
No abstract has been registered