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.
2012
Sammendrag
Nye problemer forårsaket av Phytophthora-arter har utløst en rekke fytosanitære undersøkelser i planteskoler, parker og produksjons felter i Norge de siste årene. Flere Phytophthora-arter og nye vertplanter for allerede kjente arter er påvist.
Sammendrag
I bøkeskogen i Larvik vart det i 2012 påvist Phytophthora-skade på fleire tre. I samband med ny E18 forbi Larvik må store mengder masse flyttast, noko som kan spreia Phytophthora spp. til nye område dersom massen inneheld Phytophthora spp. Statens vegvesen bad difor Bioforsk i 2012 om ei kartlegging av evt. Phytophthora-smitte i anleggsområdet, noko som resulterte i funn av fleire Phytophthora-artar. Aktuelle tiltak vert diskutert i rapporten.
Forfattere
Toril Drabløs Eldhuset Isabella Børja Roman Gebauer Paal Krokene Nina Elisabeth Nagy Josef Urban Daniel VolarikSammendrag
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Sammendrag
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Forfattere
Roman Gebauer Daniel Volařík Josef Urban Isabella Børja Nina Elisabeth Nagy Toril Eldhuset Paal KrokeneSammendrag
Conifer needles are extraordinarily variable and much of this diversity is linked to the water transport capacity of the xylem and to xylem conduit properties. However, we still know little about how anatomical characteristics influence the hydraulic efficiency of needle xylem in different parts of the crown. In this study we evaluated needle function and anatomy in Norway spruce families exposed to different light conditions. We measured tracheid and needle characteristics of sun-exposed and shaded current-year needles in two experimental plots: a control plot and a thinned plot with 50% reduction in stand density. Sun-exposed needles had a larger tracheid lumen area than shaded needles, and this was caused by a larger maximum tracheid lumen diameter, while the minimum lumen diameter was less plastic. Sun-exposed needles had also higher theoretical hydraulic conductivity than shaded needles. Thinning leads to increased radiation to the lower branches, and presumably exposes the upper branches to stronger water stress than before thinning. Thinning affected several needle parameters both in sun-exposed and shaded needles; tracheid lumens were more circular and minimum tracheid lumen diameter was larger in the thinned plot, whereas maximum tracheid lumen diameter was less plastic on both plots. This study demonstrates that needle xylem structure in Norway spruce is clearly influenced by the light gradient within the tree crown.
Forfattere
Nina Elisabeth Nagy Harald Kvaalen Monica Fongen Carl Gunnar Fossdal Nicholas Clarke Halvor Solheim Ari HietalaSammendrag
Pathogen challenge of tree sapwood induces the formation of reaction zones with antimicrobial properties such as elevated pH and cation content. Many fungi lower substrate pH by secreting oxalic acid, its conjugate base oxalate being a reductant as well as a chelating agent for cations. To examine the role of oxalic acid in pathogenicity of white-rot fungi, we conducted spatial quantification of oxalate, transcript levels of related fungal genes, and element concentrations in heartwood of Norway spruce challenged naturally by Heterobasidion parviporum. In the pathogen-compromised reaction zone, upregulation of an oxaloacetase gene generating oxalic acid coincided with oxalate and cation accumulation and presence of calcium oxalate crystals. The colonized inner heartwood showed trace amounts of oxalate. Moreover, fungal exposure to the reaction zone under laboratory conditions induced oxaloacetase and oxalate accumulation, whereas heartwood induced a decarboxylase gene involved in degradation of oxalate. The excess level of cations in defense xylem inactivates pathogen-secreted oxalate through precipitation and, presumably, only after cation neutralization can oxalic acid participate in lignocellulose degradation. This necessitates enhanced production of oxalic acid by H. parviporum. This study is the first to determine the true influence of white-rot fungi on oxalate crystal formation in tree xylem.
Sammendrag
In 2008, an epidemic caused by a new Neonectria sp. was discovered on white fir (Abies concolor) in several counties in southern Norway [1]. Later the pathogen was also found on other fir species in Norway and Denmark [2]. Typical symptoms and signs were dead shoots, flagging (dead branches), canker wounds, heavy resin flow, and occasionally red fruiting bodies (perithecia). Pathogenicity tests on several Abies spp. proved the fungus to be very aggressive, which corresponds well with observations of mortality of white fir and subalpine fir (A. lasiocarpa) from different age classes under field conditions. Sequencing of the internal transcribed regions (ITS) of the ribosomal DNA showed that this Neonectria sp. was most similar to N. ditissima (only 5 bp different from isolates in the GenBank), a common pathogen worldwide on broad leaf trees. The ITS sequences were very different (> 20 bp) from N. fuckeliana, a well-known fungus on Norway spruce in Scandinavia and other parts of the world, especially in the northern hemisphere. In 2011, the new Neonectria species was found on diseased trees in a Danish nordmann fir (Abies nordmanniana) seed orchard. Resin flow was seen from mature cones, and tests revealed that the seeds were infected by the Neonectria sp.
Sammendrag
I Bergen, Haugesund, Stavanger og Larvik har vi funne typiske Phytophthora-symptom på bøk (Fagus sylvatica). Ordet Phytophthora tyder planteøydeleggjar (phyto =plante, phthora=øydeleggjar) og skadeorganismar i denne slekta kan ta livet av store tre på relativt kort tid. På verdsbasis spreier Phytophthora-artar seg stadig til nye lokalitetar og vertplanter. Dette skuldast i stor grad internasjonal handel med planter. Det fins over 100 ulike Phytophthora-artar, og mange av dei er svært aggressive og har eit vidt vertplantespekter. Generelt trivest dei best i fuktig jord og vatn, men dei har også tjukkvegga sporar (oosporar) som kan overleva i årevis i jord under ugunstige tilhøve for patogenet. Så langt har vi isolert P. cambivora og P. plurivora frå bøk i Noreg. Begge artane er kjende som skadegjerarar på bøk i parkar og skogplantasjar i mange land i Europa og USA og vert sett på som ein stor trus¬sel mot naturområde.
Sammendrag
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Sammendrag
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