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
Authors
Tor J. JohansenAbstract
No abstract has been registered
Abstract
Histological properties of the graft union between a rootstock and scion may provide a mechanistic explanation why dwarfing rootstocks are able to reduce the growth of the tree. In order to investigate the relationship between growth and the amount of functional xylem tissue of potted sweet cherry trees, an experiment was conducted during 2002-2003. One year old field budded and bench grafted (from greenhouse) sweet cherry trees of the cultivars Van, Ulster and Lapins in all combinations of the three rootstocks Prunus avium seedling, Colt and Gisela 5 were grown in pots for two growing seasons. After shoot extension had terminated when trees were in full leaf the second year, the total growth of the different parts of the trees and the functional area using safranin staining were measured. The total mass production (tree dry weight, the length of two year old wood and number of leaves) was significantly larger in the budded trees. Similarly the trunk cross sectional area was significantly larger 10 cm above and in the middle of the graft union, but not 10 cm below it. The Colt trees were the most vigorous followed by the seedling and Gisela 5. Minor differences between the different cultivars were registered. Xylem staining with aqueous safranin combined with quantitative image analysis showed that the rootstock stem had a higher proportion of stained tissue than the scion stem. Sections taken in the middle of the graft tissue and 10 cm above showed that the proportion of stained tissue declined proportionally with the distance from the roots. The total area of stained stem xylem was larger for the two vigorous rootstocks compared to Gisela 5. Small differences were observed between cultivars and propagation methods.
Authors
Kristine Marie Olsen Unni Synnøve Lea Rune Slimestad Michel Verheul Cathrine LilloAbstract
No abstract has been registered
Abstract
A main scourge in Norwegian sheep farming is tick-borne fever (TBF) caused by the bacteria A. phagocytophilum and transmitted by the tick Ixodes ricinus. The aim of this poster is to present a new research project on resistance to TBF in sheep (2007?2010).
Authors
Nicholas Clarke Yijie Wu Line Tau StrandAbstract
Boreal forests are increasing in age partly due to reduced logging and efficient wildfire control. As a result, they also stock more carbon. Whether increased forest C stock causes greater production of dissolved organic carbon (DOC) is uncertain. DOC in bulk precipitation, throughfall and soil water was studied in 10-, 30-, 60- and 120-year-old stands of Norway spruce (Picea abies (L.) Karst.) DOC concentrations in throughfall and O horizon soil water followed the order 10<30<60 = 120 and 10 = 30<120<60, respectively. DOC fluxes followed the order 10 = 30<60 = 120 in throughfall, while no significant difference between stands was found for O horizon soil water. Above-ground tree litter varied according to 10<30<60 = 120, a pattern identical to that for DOC concentrations in throughfall and resembling but not identical to that for DOC concentrations in O horizon soil water. This indicates additional sources for DOC in soil water. Seasonality in DOC concentrations was observed at the base of the O horizon, and seasonality in DOC fluxes in both throughfall and O horizon soil water. Our results suggest differences in the polarity of DOC between the 10-year stand and the others, which we interpret as reflecting the lack of grown trees and possibly the different vegetation on the 10-year stand.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
The performance of the plum rootstocks Marianna, Pixy and Wangenheim using St. Julien A as a standard to the cultivars `Avalon", `Edda", `Excalibur", `Jubileum", `Reeves" and `Victoria" was assessed in a field trial in western Norway at 60" North. Trees were planted in spring 1999, the plant material was one-year-old whips, spaced 2.0 x 4.5 m and formed with a central leader as free spindles. Soil management was grass in the alleyways and herbicide strips 1-m wide along the tree rows. Tree vigour, yield, fruit size and yield efficentcy were evaluated for the six subsequent years. Tree size was significantly affected by the rootstocks after six years growth. Wangenheim produced the smallest and St. Julien A and Pixy the largest trees as measured by trunk cross-sectional area in average for the different cultivars. St. Julien A and Pixy were the most productive rootstocks for the cultivars. However, Pixy produced significant larger yields per tree to the cultivar `Reeves" than St. Julien A. Trees on Pixy were the most yield efficient for all cultivars with the exception of `Victoria". The fruit sizes were in general large for all cultivars and became little affected by the different rootstocks. Fruit quality characterized by the content of soluble solids was in general high and did not differ between trees on the various rootstocks. The cultivar `Avalon" had the highest contents of soluble solids.
Abstract
No abstract has been registered
Authors
Ketil Kohmann Øystein JohnsenAbstract
The object of this study was to obtain Norway spruce seedlings with buds set, ready for summer planting from the 1st of July. With an early long night treatment we prevented flushing of the newly formed terminal buds, ceased height growth, but slightly reduced hardiness in buds and needles. Nevertheless, a sufficient hardiness level in the autumn was acquired at a Norwegian nursery at 59°46’ N, with plants of the local provenance given a long night treatment (14 hours) for 13 days from the 25th of June. The similar treatment at a nursery at 64°30’N did not give the same result; all treatments led to a second flush with resumed growth of the local provenance. A trial with seed lots from several provenances was therefore performed at this nursery, and a significant correlation between the critical night length of the seed lot, and their ability to produce non-flushing buds, was found; the longer the critical night length of the seed lot, the less non-flushing buds. Responses at the northern nursery are probably due to the non existing dark period after termination of the treatment, and a too short treatment period to attain bud dormancy. An early and successful long-night treatment will, in addition, produce shorter seedlings with a larger root collar diameter.