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.
2001
Sammendrag
Tørråte har vært fraværende på Island i mange år, men var vanlig forekommende i 1990 og 1991. Sjukdommen ble ikke observert i 1992-1998. I 1999 ble det igjen funnet tørråteangrep. Blader med tørråte ble sendt til Planteforsk Plantevernet som isolerte soppen og gjennomførte tester av krysningstype og metalaksylsensitivitet. En av 15 undersøkte isolater var A2, de resterende var A1. Metalaksylresistens ble også påvist. Undersøkelsen viser at den "nye" tørråtepopulasjonen også er tilstede på Island.
Forfattere
Malin Elfstrand Carl Gunnar Fossdal Folke Sitbon Olof Olsson Anders Lönneborg Sara von ArnoldSammendrag
Peroxidases constitute a large family of proteins found in all higher plants. Owing to the complexity of the peroxidase isoenzyme family it has been difficult to assess the precise function of individual peroxidase enzymes.In this work we have studied the effects of an endogenous peroxidase-like gene from Norway spruce [Picea abies (L.) Karst], spi 2, on the development and growth of Norway spruce somatic embryo plants.Embryogenic cells of Norway spruce transformed with spi 2 under control of the maize ubi-1 promoter showed up to 40 times higher total peroxidase activity than the control cells; regenerated plants overexpressing spi 2 showed an increased total peroxidase activity.Based on these results and the overall sequence similarity with cationic peroxidases we conclude that spi 2 encodes a peroxidase. Overexpression of spi 2 resulted in increased sensitivity to stress, leading to a reduction in epicotyl formation and in height growth compared with control plants. The plants overexpressing spi 2 also showed a deeper phloroglucinol staining but similar levels of Klason lignin.
Forfattere
Trygve S. AamlidSammendrag
Artikkelen gir en oversikt over høstearealer og gjennomsnittsfrøavlinger i norsk frøavl i 1999 og 2000. Årsaker til avlingsvariasjonen blir diskutert. Artikkelen gir også en oversikt over forsøksvirksomheten innafor frøavlen i 2000.
Forfattere
Ketil HaarstadSammendrag
Det er ikke registrert sammendrag
Forfattere
Ketil HaarstadSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
P.I. KraftSammendrag
Det er ikke registrert sammendrag
Forfattere
R. Bach B. BraskerudSammendrag
Fangdammene Selte, Fossum og Vaker ligger i Steinsfjordens nedbørsfelt på Ringerike 4 mil nordvest for Oslo. På oppdrag fra Hole og Ringerike kommune, har Jordforsk målt tilbakeholdelsen av sediment og fosfor i dammene fra 1996-2000. Fangdammene består av følgende komponenter: sedimentasjonskammer, våtmarksfiltre og overrislingssoner. Terrengforholdene har gjort at utformingen er ulik. Tilbakeholdelsen av sediment og fosfor i både Selte, Fossum og Vaker er målt ved årlig prøvetaking av sedimentoppbygging i sedimentasjonskamre og våtmarksfiltrene. Steinslettas landbruksareal er lite erosjonsutsatt. Sedimentasjonsmengden varierer mellom fangdammene, og fra år til år. Det skyldes forskjeller i fangdammenes størrelse og tilførsler fra nedbørsfeltet. I prøvetakingsperioden på 5 år er det holdt tilbake 173 tonn jord og 170 kg fosfor i Selte. I Fossum er det holdt tilbake 61 tonn jord og 49 kg fosfor. I Vakers sedimentasjonskammer har den totale tilbakeholdelsen vært på 591 tonn jord og 589 kg fosfor. Våtmarksfiltrene har totalt holdt tilbake 64 tonn jord og 57 kg fosfor. Det ser ut som om mengden tilbakeholdt jord og fosfor har lagt seg på et høyere nivå de siste 3 årene av prøvetakingsperioden for alle dammene. Årsaken til dette kan være økt erosjon på grunn av mer nedbør. Oppfyllingshastigheten varierer, men det vil trolig være nødvendig med tømming i flere av anleggene i løpet av en 10 års periode. Stofftapet fra Steinsletta og Åsa ligger på grenseverdien 12-72 kg jord/da i områder med slake hellinger. I brattere terreng ligger grenseverdiene på 125-747 kg jord/da.
Forfattere
Bjørn Ivar HonneSammendrag
For a diploid one locus two alleles model it is shown that the parameter space for all possible genotypic compositions of the population is a triagle. The hardy-Weinberg equilibrium is a borderline between the area with excess of homozygotes, comprising 2/3 of the total, and the area with deficiency of homozygotes, 1/3 of the total. A generalized model for factorial mating is used to show that the within family genetic variance is a function of the frequency of heterozugous parents. The exposed additive genetic variance and the GCA among families from polycrosses will therefore increase with an excess of homozygous parents compared to H-W-equilibrium frequencies. It is shown that dividing breeding populations into subpopulations leads to this excess, and a simulation study indicates that GCA on the average will increase about 35% with subdivision of the breeding population. A breeding strategy, with recurrent selection and production of synthetics which utilises this, is described.
Forfattere
Aksel GranhusSammendrag
The risk of logging damage to residual trees (height >3.0 m) and advance regeneration saplings (height 0.5–3.0 m) was evaluated after mechanized (single-grip harvesters + forwarders) and motor-manual (chain saw + skidding) selection harvesting in studies I and II. Harvesting took place during the winter season. Mechanized harvesting caused the highest injury rates, and the difference was highest at high cutting intensity in densely stocked stands. Another important difference between the two operating methods was the spatial distribution of the injury risk relative to striproads. The most important injuries on the larger (>3.0 m) trees were stem- and root wounds, and loss of branches. Wounds tended to be larger, and crown injuries more serious, after mechanized harvesting, but differences were not statistically significant. The most frequent injuries on saplings were crown injuries (loss of branches, stem breakage) and stem lean. In motor-manually harvested stands saplings without pre-harvest deformities in the form of top- or leader defects were more prone to damage than saplings with such defects. A similar difference was not found in stands subjected to mechanized harvesting. This result was attributed to the different work patterns during felling and processing with the two operating methods, in combination with the spatial distribution of saplings of different quality relative to larger trees and stand openings. In study III sapling mortality, and recovery from logging damage in a five-year period after selection harvesting, was investigated. Mortality on the different plots (n=11) was highly variable. For saplings without previous logging damage mortality was related to pre-harvest vigour, and increased with increasing cutting intensity in the immediate surrounding of the sapling. Unspecified site factors also contributed to explain the probability of mortality. Saplings that had been pushed over during harvesting often survived and recovered, while injuries to the crown led to poor survival. Crown injuries were most common on plots subjected to mechanized harvesting, while stem lean was correspondingly important on motor-manually harvested plots. Whether this pattern was attributed to differences in temperature at the time of harvesting (winter), or operating method, is uncertain. In study IV advance regeneration responses in terms of height growth, needle dry weights, and foliar nutrient concentrations were compared after three different release treatments: untouched control, selection harvesting with 50-60 % removal of basal area (BA50-60), and patch cut (25x25 m - 0.063 ha clear-cut). The foliar analyses were carried out five years after treatment, and included dominant and co-dominant (overstorey) trees on control and BA50-60 plots. Height growth and needle dry weights of saplings generally increased with increasing overstorey removal. The growth response was explained by an interaction of foliar nitrogen concentration in current (C) and one-year-old (C+1) needles, and degree of overstorey removal. The foliar analyses did, however, not confirm improved N status after cutting. Increasing overstorey removal led to a reduction of K (C), Mg (C+1) and B (C, C+1) in saplings. A parallel decline of B (C+1) occurred in the overstorey trees (BA50-60). Saplings on control plots had higher concentrations of K and Cu in C-needles, relative to overstorey trees. The influence of neighbour tree basal area on sapling height growth and presence of natural defects (top- and leader damage) was examined in study V. The three stands selected for the study had not been subjected to cutting for several decades, and basal areas ranged from 25–33 m2 ha-1. The relationship between growth and four basal area variables was evaluated: basal area (m2 ha-1) of taller (>3.0 m) neighbour trees within 2.82, 3.99 and 5.64 m radius from the sapling (25, 50 and 100 m2 circular plots), and basal area (m2) of trees within 5.64 m radius weighted according to distance from the sapling. A reduction of growth attributed to increasing basal area of neighbour trees was only observed for the tallest saplings (2.1-3.0 m). Between 33 and 42 % of the saplings had leader- or top defects, and damage frequencies increased with declining distance to the nearest taller neighbour tree.