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.
1993
Authors
Richard HorntvedtAbstract
No abstract has been registered
Authors
Oddvar SkreAbstract
The measurements were carried out with Warburg manometric technique on excised leaf discs. The plants had been grown for six weeks in varying temperature in continuous light. Photosynthetic rates were also measured at elevated CO2 level. The relationship between gas exchange rates and chemical composition was studied by multiple regression analysis. In accordance with earlier studies a strong acclimation effect of temperature was found. Long-term low temperature treatment caused a reduction in photosynthetic rates in all birch populations, and increased respiration rates in the two broadleaf species. There was a strong reduction in the temperature coefficient of dark respiration with decreasing acclimation temperatures in mountain birch leaves from southern populations. There was also a relatively high soluble sugar content and low chlorophyll content in low temperature treated plants. Birch from Central Norway (62 N) showed relatively high net photosynthesis rates compared with the populations from southern Norway (60 N) and higher chlorophyll content per unit area.
Authors
Ø. Austarå Fred Midtgaard T. SætherAbstract
No abstract has been registered
Authors
Dan AamlidAbstract
No abstract has been registered
Authors
Anders HolteAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Halvor SolheimAbstract
No abstract has been registered
Authors
Oddvar SkreAbstract
Seedlings of mountain birch and lowland birch were grown for two seasons in fertilized peat at two different elevations in south-western Norway at 60 N (50 and 450 meter). Seedlings from a local mountain birch population from western Norway were most successful at the high elevation site in terms of annual production, and had the highest C/N ratio, while the lowland population and the lowland birch seedlings showed the highest growth rates at the low-elevation site. The C/N ratios in these plants, however, were very low. It is concluded that the survival strategy is different at the two sites. At low-elevation sites the competition factor seemed to be the main selective force, and the most fast-growing plants were most successful, while at high elevations abiotic factors came into account, and a high source strength rather than high growth rates seemed to be the most important factor for plant survival. Chemical analysis of annual stemt tissue showed that all birch populations increased their concentrations of soluble sugars, soluble proteins and organic phosphorus in winter as a response to frowt hardening, the highest concentrations usually found in subarctic and subalpine populations.
Abstract
In a field experiment in central Sweden, the vigour of 25-yr-old Scots pines was manipulated by pruning, prior to inoculation with Leptographium wingfieldii and Ophiostoma minus, two blue-stain fungi associated with Tomicus piniperda. Our main purpose was to correlate fungus invasion and host defence reactions with host vigour. Both fungi invaded the inner bark and the sapwood at the points of inoculation. L. wingfieldii caused larger lesions in the bark, but O. minus tended to grow faster in the sapwood. The flow of primary resin was related to tree vigour, whereas carbohydrates present in needles and stem phloem were not. Lesion formation and the content or composition of resin acids in lesions did not differ between fungi or pruning treatments.
Authors
Inger HansenAbstract
No abstract has been registered