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
Sammendrag
Because light is assumed to suppress sporulation of many downy mildews (DM), it is a common component in forecast models. We evaluated effects of light intensity and quality, temperature, and diurnal periodicity on sporulation of Bremia lactucae, the causal agent of lettuce DM. We found that suppression of sporulation by light was strongly dependent upon temperature; with little suppression by light below 10 ºC. The greatest suppression of sporulation occurred at 400-450 nm, although a lesser effect was detected at 450-550 nm. At 15 ºC, a diurnal pattern of sporulation was observed independent of light and darkness. Current forecast models for lettuce DM use sunrise and sunset to delimit the hours during which leaf wetness and high RH can induce sporulation. Our results indicate that effects of short nights and extended twilight conditions, as in Nordic countries, should be incorporated into forecast models. Also, temperature should modify model predictions of sporulation, as the suppression of sporulation by light may be greatly reduced at temperatures below 15-20 ºC. The diurnal rhythm could interact with light and temperature to confound the results of controlled environment studies, and may be the controlling factor in timing of sporulation at low temperatures.
Sammendrag
The role of light in control of cyathia abscission and bract discolouration in poinsettia (Euphorbia pulcherrima) is unclear. The aim of this work was to study the involvement of photosynthetic photon flux (PPF) and extended photoperiod from 10 to 13, 16 or 24 hours with supplemental lighting at the end of the culture period on development of bract discoloration at marketing stage of the plants, and the postharvest performance of cyathia abscission in interior climate of two poinsettia cultivars, `Lilo" and `Millenium". The plants were grown at different photoperiods with supplemental PPF of 73 and 146 µmol m-2 s-1 at plant level. The extended supplemental light treatments were given for one, two or three weeks at the final cultivation period before marketing stage. Extended photoperiod from 10 up to 24 h had no influence on discolouration of the bracts as black and greenish areas of the bract in `Millenium". In contrast, `Lilo" developed serious bract discoloration at photoperiods longer than 13 h. The most serious symptom appeared at 24 h and three weeks of exposure time. Extended photoperiods with supplemental lighting enhanced cyathia abscission at the end of the culture time and during the postharvest test in interior climate. `Millenium" had a better ability to retain cyathia than `Lilo". It is concluded that poinsettia plants should be grown in a photoperiod not longer than 13 h in order to maintain a low rate of cyathia abscission at the end of the production period and during the first 2-3 weeks in interior climate.
Forfattere
Roar Moe Erling Fløistad dag-ragnar blystadSammendrag
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Forfattere
Claudia Melis Astrid Buset Per Arild Aarrestad Oddvar Hanssen Erling Meisingset Reidar Andersen Arne Moksnes Eivin RøskaftSammendrag
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Forfattere
Therese With Berge Jan NetlandSammendrag
Status i Norge og internasjonalt presenteres.
Forfattere
Lise GrøvaSammendrag
Presentasjon av forskningsprosjektet: Improved welfare in sheep production. Preventive measures, disease resistance and robustness related to tick-borne fever in sheep.
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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