Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2006
Forfattere
Bernhard Speiser L Tamm T Amsler J Lambion C Bertrand Arne Hermansen Theo Ruissen Palle Haaland J Zarb J Santos P Shotton S Wilcockson P Juntharathep R Ghorbani C LeifertSammendrag
Late blight of potatoes, caused by Phytopthora infestans, is particularly difficult to prevent or control in organic agriculture. In this study, the host resistance of selected varieties to foliar and tuber blight and their yield under organic growing conditions were assessed in trials carried out in four countries (Switzerland, France, England and Norway) in 2001 and 2002. The objective was to identify new, more resistant varieties, which might replace some of the more susceptible varieties which are currently grown in organic agriculture. In each country, five test varieties were compared with two reference varieties, identical for all sites, and two local popular varieties. In addtion, the effect of copper fungicides was assessed for all varieties in England. Several new potato varieties (Appell, Derby, Innovator and Naturelle in Switzerland; Derby, Eden, Escort and Naturella in France; Sarpo Axona, Eve Balfour, Lady Balfour, Sarpo Mira and Sarpo Tomina in England; N89-1756 and N92-1538 in Norway) proved far less susceptible to foliar and tuber blight than most of the varieties currently grown. However, market requirements could restrict their introduction into practice. The copper fungicide treatment reduced foliar blight severity in all varieties tested in England and in both years, by 27 % on average, and increased yield by 20 % on average, but did not affect tuber blight. In organic farming, a shift towards the use of blight resistant varieties should be strongly encouraged, although this is unlikely to eliminate the need to use copper fungicides.
Forfattere
Christian UhligSammendrag
Soil erosion control mats generally prevent erosion and enhance soil physical conditions for plant growth. However, commonly used mat materials as coconut fiber and synthetic fabrics are naturally poor in plant nutrients and thus do not improve soil chemical properties. The main aim of this paper is to propose alternative materials for the production of erosion control mats, which mutually improves soil physical and chemical properties. Theoretically, the perfect material for soil erosion control mats combines all essential physical properties, e.g. physical stability, together with beneficial biological and chemical properties, like adequate bio-degradability and plant nutrient release. Furthermore, mat material, which promote soil organic matter (SOM) enrichment and thus soil development, would be favourable. From the economically and practically point of view, mat material should be cheap, available and workable. According to a literature review and practical experiences organic material derived from Epilobium angustifolium (fireweed) fulfil several of the above listed requirements. Furthermore, fireweed widely appears in early successional phases within several boreal and temperate vegetation types, and can consequently be considered a natural component for revegetation and soil development of these ecosystems. So far no allelopathic effects of its plant residues have been reported. Additionally benefits by using fireweed for the production of soil erosion control mats may derive from its ability to effectively disperse vegetative and generatively. Root cuttings as small as 2.5 x 1.5 mm were capable of producing adventitious buds and single plants might yield as many as 80,000 seeds per year with a germination rate of up to 100 % (Jobidon 1986 and literature within). Thus, the use of entire fireweed plants, including roots and matured seeds for the production of soil erosion control mats may indirectly support revegetation efforts of disturbed sites. According to Broderick (1990) and Mitich (1999) fireweed may prove to be a good species for artificial revegetation and land rehabilitation projects.
Sammendrag
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Sammendrag
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Forfattere
Filip Moldan O. Janne Kjønaas Arne Olav Stuanes Richard Frederic WrightSammendrag
Beginning in 1991, we have added nitrogen (N) to the 0.5-ha, N-poor, coniferous-forested catchment G2 NITREX at Gårdsjön, Sweden, to investigate the consequences of chronic elevated N deposition. We have added 40 kg N ha−1 yr−1 in fortnightly doses of NH4NO3 to the ambient 15 kg N ha−1 yr−1 by means of a sprinkling system. NO3 concentrations in runoff increased during 13 years from < 1 to 70 μeq L−1, and in 2004 comprised about 10% of N input. Inhibition of NO3 immobilisation due to increased availability of NH4 might explain the increased leaching of NO3. C and N pools in the forest floor increased but C/N ratio has not changed. The increase in NO3 leaching thus occurred independently of change in C/N ratio. The results from Gårdsjön demonstrate that increased leaching of inorganic N and decrease in C/N ratio respond to increased N deposition at greatly different time scales. NO3 concentrations increased in runoff although the C/N ratio of forest floor has not changed.
Forfattere
Paal KrokeneSammendrag
Bark beetles and associated phytopathogenic fungi elicit defence responses in conifers that may interfere with beetle establishment and development. Norway spruce is serving as a useful model species for studies of induced defences elicited by beetle attacks, fungal inoculation, and treatment with chemical elicitors.When trees are pretreated with a sublethal dose of fungal inoculations or with the phytohormone methyl jasmonate they become much more resistant to subsequent bark beetle attacks or artificial mass inoculations with fungi. This induced disease resistance follows dose-response dynamics, is nonspecific with respect to the pretreatment organism, appears to be nonsystemic, takes weeks rather than days to become activated, and can also be activated by mechanical wounding alone.Application of methyl jasmonate to Norway spruce stems induces a massive increase in terpene levels and external resin flow on the stem, whereas no increase is observed in soluble phenolics. Methyl jasmonate-application also leads to significantly less bark beetle colonization, with shorter parental galleries and fewer eggs laid in treated bark. There were also reductions in the number of beetles produced and the mean dry weight per beetle in methyl jasmonate-treated bark. Furthermore, fewer beetles were attracted to conspecifics tunneling in MJ-treated bark.The exact mechanisms responsible for induced resistance in Norway spruce and other conifers have not been determined, but inducible anatomical defense responses such as changes in polyphenol-containing parenchyma cells (PP cells) in the phloem and induction of traumatic resin duct formation in the sapwood seem to play an important role.
Forfattere
Ingerd Skow Hofgaard Åshild Ergon Birgitte Henriksen Hilde Kolstad Helge Skinnes Yalew Tarkegne Anne Marte TronsmoSammendrag
Abstract: Development of Fusarium head blight (FHB) was studied in winter wheat pre-treated with potential defence activators. Several chemicals were pre-screened for their capacity to reduce development of Microdochium nivale in a detached leaf as¬say. Selected compounds were further tested for their capacity to reduce Fusarium culmorum development in heads of winter wheat in greenhouse and field experiments. In the detached leaf assay, leaves from plants pre-treated with a foliar fertilizer displayed reduced disease development compared to untreated control. A significantly reduced disease develop¬ment of FHB in plants pre-treated with the foliar fertilizer was also registered in the greenhouse and field experiments. In the field experiment, harvested grains from plants treated with the foliar fertilizer had up to 75% reduction in Fusarium infected seeds com¬pared to grains from non-treated plants.
Forfattere
Leiv Mortensen Brita Toppe H.R. GislerødSammendrag
The influence of high CO2 concentrations and diurnal variation in air temperature on the development of powdery mildew (Podosphaera pannosa) was studied in different cut rose cultivars grown under 20 h day"1 supplementary lighting. An increase in CO2 concentration from 380 to 1000, or 2000 "mol mol"1, did not affect development of the disease in cvs. `Escimo" and `Red Champ". Compared to constant temperature, a temperature drop from 22 °C to 16 °C over the course of 8 h significantly enhanced the attack of powdery mildew in both cultivars, while the same drop in temperature over the course of 4 h had no effect. In another experiment, a temperature increase from 20 °C to 26 °C reduced the attack of powdery mildew in the four cultivars studied (`Escimo", `Red Champ", `Jade" and `Cezanne") when applied over 4 h and even more so when applied over 8 h. Number of days until flowering was unaffected by CO2 concentration, but was increased by a drop in temperature and decreased by a rise. Fresh weight per shoot was increased by CO2 enrichment, a drop in temperature and by a 4 h period of increased temperature. The results are discussed in relation to an optimal greenhouse climate with respect to rose production and powdery mildew control.
Sammendrag
White clover (WC, Trifolium repens L.) or red clover (RC, Trifolium pratense L.) was grown in mixture with grasses. Samples of the mixtures and pure clovers were taken during three cuts, and the fatty acids (FA) compositions were determined. The clover species had no significant effect on the individual FA contents of the leys (g kg-1 dry matter (DM)), nor on the total FA content. Pure clovers had lower content of all individual FA (8.2 vs. 12.4 g kg-1 DM) than mixtures; the contents of all FA decreased with increasing percentage of clover in the mixture, but the decrease was weaker for C18:3n-3 than for the other FA. Although pure WC and RC had similar FA contents, the relative proportions (percentage of total FA content) of C16:0 and C18:3n-3 differed; RC had a higher proportion of C18:3n-3 and a lower proportion of C16:0. These results are partly in contradiction with previously reported.
Sammendrag
White clover (WC, Trifolium repens L.) or red clover (RC, Trifolium pratense L.) was grown in mixture with grasses. Samples of the mixtures and pure clovers were taken during three cuts, and the fatty acids (FA) compositions were determined. The clover species had no significant effect on the individual FA contents of the leys (g kg-1 dry matter (DM)), nor on the total FA content. Pure clovers had lower content of all individual FA (8.2 vs. 12.4 g kg-1 DM) than mixtures; the contents of all FA decreased with increasing percentage of clover in the mixture, but the decrease was weaker for C18:3n-3 than for the other FA. Although pure WC and RC had similar FA contents, the relative proportions (percentage of total FA content) of C16:0 and C18:3n-3 differed; RC had a higher proportion of C18:3n-3 and a lower proportion of C16:0. These results are partly in contradiction with previously reported.