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.
2008
Forfattere
Ragnhild Nærstad Vinh Hong Le Arne Hermansen Asko Hannukkala Bent J. Nielsen Jens Grønbech Hansen Lina Grönberg Björn Andersson Jonathan YuenSammendrag
A new potato late blight forecasting model based on hourly weather date is developed based on trials with spore traps and trap plants. The model is built up of sub models for for the different steps in the epidemiological cycle, spore production, release, survival and infection. Long humid periods are suitable for spore production, at moderate humidity the process goes slower. The amount of viable attached sporangia is reduced by drought, and some spores are washed off during rain. Spores are released into the air by a drop in humidity or increased radiation, but the release is inhibited at high leaf wetness. The amount of viable released spores is strongly inhibited by solar radiation. The spore load is also reduced by precipitation and by germination. The leaf wetness duration have to sufficient for the spores to germinate and infect. The risk of blight development is a function of the amount of viable released spores and the duration of leaf wetness.
Sammendrag
Runoff time series are known to contain long term structures on interannual to decadal time scales. Investigating spatial patterns of long term structures is a way to elucidate the relationship between external forcings and watershed properties. This would be a valuable contribution to an improved water resources management. Singular System Analysis (SSA) is a powerful technique to identify and extract significant long term components from time series. However, many observations from natural systems are prone to missing data that hamper many analysis techniques, including the SSA in its original formulation...
Sammendrag
Wood is a unique building material, but is by nature designed to deteriorate. A detailed understanding of the factors and interactions involved are important when working with service life prediction of wooden components in buildings. Wood may experience exponential fungal degradation caused by variation in the climatic factors within a small limited area and by minor imperfection in the wooden component. In this paper we put forward a new term: critical in-situ conditions (CIC). This is meant to bring the attention to the importance of looking into details in the construction design, the specific climatic factors and interactions involved. Gaining realistic and useful data for prediction of service life is only possible by controlling and understanding the factors that are target specific for a wooden component or even only a part of it. Performing measurements in a right way and in the proper part of the wooden component are vital for getting useful data for further processing. The objective in this paper is to exemplify the CIC in inservice situations and to describe the factors and interactions that control the service life. Case studies were performed on a building at Bryggen in Bergen, on a hunting cabin on Svalbard, on several wooden windows in the southern part of Norway and on an external wall of a residence house in Ås.
Sammendrag
Tree-killing bark beetles conquer healthy trees by means of pheromone mediated mass-attacks. The initial attackers select trees through a process of random landing and processing of tactile and short-range chemical stimuli. Inside acceptable hosts they produce aggregation pheromones that attract additional attackers. In a recent field experiment we induced defense responses in 60-year-old Norway spruce trees and monitored colonization by the spruce bark beetle Ips typographus. Induced stem sections had significantly less beetle colonization than control sections, with shorter parental galleries and fewer eggs deposited. In addition, fewer beetles were attracted to beetles tunnelling in induced bark. This reduced ability to attract conspecifics suggests that induced host defenses interfere with beetle pheromone production or emission. The mechanisms responsible for this are unknown, but may involve emission of volatile terpenes such as (E)-b-farnesene and linalool, which have been shown to increase up to 100-fold in induced Norway spruce trees. These compounds have been reported to attract natural enemies of herbivores or repel herbivores directly in other conifer-insect interactions.
Forfattere
Arnfinn Nes Bjørn Hageberg Jørn Haslestad Rune HagelundSammendrag
The cultivar `Veten" has for many years been nearly the only red raspberry cultivar grown in Norway. The cultivation methods have therefore been developed and adapted to this cultivar. In later years the cultivar `Glen Ample" has become the most used cultivar. This cultivar also grows vigorously, but has a different growth habit from `Veten". The primocanes grow taller and the laterals are longer so the rows are mostly very high and dense. An experiment was established to find the optimal cane height and density for growing high quality raspberry of this cultivar. The experiment was established in a four-year-old field with `Glen Ample" in the spring of 2004. The canes were fixed to two wires that were 90 cm apart and every second cane was fixed to each wire. The canes were topped two buds above the wire, and the height of the wires was either 140 cm or 160 cm. Different cane densities were established by leaving 6, 8 or 10 canes per meter row at pruning early in the spring. There was no interaction between the experimental factors neither on berry size nor yield. The 20 cm difference in cane height did neither affect yield nor berry size. Cane density showed significant effects on yield. Crop per cane and per hectar increased with cane density. Berry size was not affected. The berries were, however, 20 per cent bigger the second year when the field was under polyethylene tunnels.
Sammendrag
In greenhouse rose production, there is a trend towards the use of extreme long days (up to 24 hours lighting) and high light intensity to reduce problems with powdery mildew. Continuous lighting has been found to have adverse effects on some insects as well. The effect of continuous lighting on the survival, development and fecundity of the greenhouse whitefly, Trialeurodes vaporariorum on cut roses was investigated in climatic chambers with artificial light at 21oC and 70% RF. Compared to whiteflies exposed to 20:4 hours L:D, whiteflies exposed to continuous lighting had lower egg and larval/pupal survival, and lower fecundity and female longevity. Egg and egg-adult developmental time was only slightly affected.
Sammendrag
In greenhouse rose production, there is a trend towards the use of extreme long days (up to 24 hours lighting) and high light intensity to reduce problems with powdery mildew. Continuous lighting has been found to have adverse effects on some insects as well. The effect of continuous lighting on the survival, development and fecundity of the greenhouse whitefly, Trialeurodes vaporariorum on cut roses was investigated in climatic chambers with artificial light at 21oC and 70% RF. Compared to whiteflies exposed to 20:4 hours L:D, whiteflies exposed to continuous lighting had lower egg and larval/pupal survival, and lower fecundity and female longevity. Egg and egg-adult developmental time was only slightly affected.
Sammendrag
Informasjon om dyrevelferdsaktivitet i Bioforsk Økologisk, ANIPLAN kalv og SWATIC sept 2008.
Forfattere
Inger Sundheim FløistadSammendrag
Info fra prosjektet, spesielt om forsøket i Lier
Populærvitenskapelig – Ingen hjelp av biostimulanter for rotutviklinga på Sør Arena
Trygve S. Aamlid
Forfattere
Trygve S. AamlidSammendrag
Våren 2007 var det store problemer med rotutviklinga på nyetablerte Sør Arena. Denne artikklen gir resultater fra et forsøk der ulike biostimulaner ble gitt til blader og/eller jord for for å få gressrøttene til å gå dypere. Produktene førte til en midlertidig bedring av grønnfargen, men hadde ingen virkning på rotdanninga i løpet av den 4 uker lange forsøksperioden.