Hopp til hovedinnholdet

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.

2000

To document

Abstract

Vi undersøkte fenologi og kjønnsratio (andel hunner) til 15 arter snylteveps som parasitterer havrebladminerflue i Norge. Studiet gikk over 6 sesonger i byggskiftet i et økologisk drevet felt ved Norges Landbrukshøyskole, og det ble brukt Malaisefeller som innsamlingsmetode (en i åkerkanten og en 60 m inn i byggskiftet). Resultatene tydet på at snyltevepshunnene var mer knyttet til kanten enn hannene og verten sin, og at mange av snyltevepsene vandret ut av åkeren en stund før tresking. De to vanligste snyltevepsartene var Cyrtogaster vulgaris (en puppeparasitt) og Diglyphus begini (en larveparasitt). Førstnevnte hadde en særlig nær tilknytning til kanten, og tidligere studier har vist at denne kan overvintre som voksen i f.eks grastuer i kanten. Hos sistnevnte fant vi en tetthetsavhengig kjønnsratio i fellefangstene: Jo flere individer i fellene, jo lavere andel var hunner

Abstract

The anatomical response of Norway spruce bark polyphenolic parenchyma cells (PP cells) to inoculation with the phytopathogenic fungus Ceratocystis polonica and attack by its bark-beetle vector Ips typographus was examined.Fungal inoculation on the periderm surface had no effect, while inoculation just below the periderm or halfway into the phloem (mid-phloem) generated detectable responses within 3 wk. The responses included increase in PP cell size and in periodic acid - Schiffs staining of PP cell phenolics, wound periderm initiation from PP cells, and cambial zone traumatic resin duct formation. Fungi were not seen in samples 3 wk after subperiderm or mid-phloem inoculation, but were found in some samples 6 and 9 wk after mid-phloem inoculation.In contrast, inoculations into the cambium resulted in partial (3 wk) or complete (6 and 9 wk) fungal colonization and death of tissue in the infected area. This indicates that PP cells have defenses capable of inhibiting fungal growth. Samples taken near bark-beetle galleries had similar anatomical responses as inoculated samples, validating the inoculation approach to studying defense responses in spruce.These results show that PP cells represent not only a constitutive defense system, but are also involved in local and remote inducible defenses against fungal and beetle attack.

Abstract

Filling wood cell cavities or modifying walls with polymer improves mechanical properties and reduces influences of moisture and biodeterioration agents. Properties of untreated wood and wood polymer composites are presented in the paper.

To document

Abstract

Sensory analysis was performed on fresh fruits, frozen non-cooked jam and traditionally cooked jam of 14 strawberry cultivars. The purpose was to characterise and compare the sensory quality of different strawberry cultivars and different types of jam. The results of the investigation were presented by means of multivariate modelling methods such as principal component analysis (PCA) and partial least squares regression (PLS). The sensory profile of cooked jam differed from that of fresh fruits and frozen jam, explaining 75% of the total variation in the first component. Cooked jam scored high for sweet taste, stickiness, bitter taste, earthy flavour, off-flavour and total intensity of taste. Frozen jam had many of the same sensory characteristics as fresh fruits and scored high for strawberry flavour, fruity flavour and whiteness, while fresh fruits scored highest for colour strength, hue and sour taste. As analysed by means of PLS, sensory colour and flavour variables of fresh fruits were able to predict 35% of sensory cooked jam variables. Analysing early cultivars alone, sensory fresh fruit variables were able to predict 69% of sensory cooked jam variables. (C) 2000 Society of Chemical Industry.

Abstract

Measurement data on air, precipitation and canopy throughfall chemistry from a network of sites have been combined to study scavenging and deposition processes, with particular emphasis on the oxidised nitrogen species.High deposition rates of oxidised nitrogen occur in coastal areas of SW Norway. These are partly caused by high precipitation rates, partly also because a large fraction of the oxidised nitrogen is present as nitrate in large particles, which are rapidly removed by both wet and dry deposition processes.High wind speeds near the coast result in high concentrations of sea-salt particles in the air and high deposition rates of both nitrate and sea-salt particles, particularly in coniferous forest stands. HNO3 contributes on average only about 10-20% to the sum of aerosol nitrate and HNO3 (sNO(3)). Still, the combined dry deposition velocity of sNO(3) to these forest stands may be between 4 and 6 cm s(-1) on average.