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
Audun KorsæthSammendrag
Det er ikke registrert sammendrag
Forfattere
Guro BrodalSammendrag
A survey of the loose smut frequencies in certified barley seed lots in Norway during 1997"2002 showed that the disease has become more prevalent and has occurred at higher infection frequencies in recent years. Laboratory analyses (embryo method) of barley seeds harvested in 2001 and 2002, including both certified and farm saved seed, showed a large number of infected seed lots with higher than expected infection frequencies. One lot of farm saved seed (cv. Otira) from 2002 had 32% seed infection. Unexpectedly high loose smut infection frequencies recorded in fields sown with carboxin treated barley seed suggest a reduced effectiveness of the fungicide. A seed treatment experiment was conducted in 2002 using both greenhouse and field trials with two infected seed lots (cv. Otira with 14.4% and cv. Fager with 6.9% infected seeds) to evaluate and compare the effect of Fungazil C (carboxin + imazalil) and Premis Robust (triticonazol + imazalil) against loose smut. Fungazil C at normal rates reduced loose smut frequencies by approximately 50% or less. At twice the normal rate, loose smut symptoms were reduced by 60-80%. Premis Robust showed more effective loose smut control, but did not confer complete control.
Sammendrag
In a preliminary experiment terminal stem cuttings (4 – 5 cm) were collected in the spring (May) from a wild population of lingonberry near Holt Research Center, Tromsø, Norway. The cuttings were rooted in peat mixed with 30% perlite with and without auxin treatment (Seradix 1 or Seradix 2: 3-indol-butyric-acid). The effect of dipping in a fungicide (Rovral) was also tested. With the best treatment, control without auxin and fungicide, as much as 66% of the cuttings rooted. Both dipping in Seradix and in the fungicide reduced rooting of the cuttings. To test the seasonal variations in rooting of lingonberry cuttings, terminal cuttings were harvested regularly every month in more than one year. The results indicate that a relatively short cold period is needed to induce bud break and shoot growth. Cuttings harvested during spring and summer rooted poorly compared to cuttings harvested in late autumn and during winter. The best rooting was obtained using cuttings harvested in September and November.
Sammendrag
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Sammendrag
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Sammendrag
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Forfattere
Ingvald Røsberg Jon Frank Arne O. StuanesSammendrag
Soil uptake of N, P, and K from the unfertilized plots leads to a depletion of these elements, but also very little leaching. Upon addition of N, P, K, Mg, Ca, and S, soil uptake and nutrient accumulation in the soil usually increased at the same time. The high doses of N, P, K, and S in the "optimal" treatment gave a distinct response with higher uptake from the soil and higher accumulation in the soil. No P was leached from the soil, while about one fourth to one third of the applied N, K, and Mg were leached. The treatment induced an unacceptably high nitrate leaching, and must therefore be regarded as "suboptimal". (c) 2006 Elsevier B.V All rights reserved. Tree growth and nutrient cycling of N, P, K, Mg, Ca, S, and B were examined after four growing seasons in a pine ecosystem in southern Norway. The Scots pine (Pinus sylvestris L.) stand, growing on a Cambic Arenosol, was 33 years old and had a medium site index class. The randomized block experiment had six treatments and three replicates: (1) control, (2) 3000 kg per hectare lime, (3) 3000 kg per hectare dolomite, (4) 3000 kg per hectare dolomite and (5) 6000 kg per hectare dolomite, both treatments (4 and 5) with the fertilizers KCl and superphosphate, and (6) 3000 kg per hectare dolomite with KCl, superphosphate, NH4NO3, kieserite, and borax, and denoted as "optimal" treatment. The "optimal" treatment gave a significantly higher annual increase in tree height and diameter, stand basal area and volume than the control and lime treatments. The dry mass of needles and branches increased slightly for the treatments nos. 3-5 compared to the control and lime treatments, with the most distinct increase for the "optimal" treatment. Highest dry mass of stem wood + bark was found for the treatments nos. 3-6. The nutrient contents in needles were highest for the "optimal" treatment, while dolomite without fertilizer elevated the Mg content in both needles and branches. The nutrient concentrations in the current year's needles increased the most for the "optimal" treatment, except for Ca and Mg. The addition of lime gave the highest concentration of Ca in needles compared to the other treatments. The amounts of N, P, S, and B in the forest floor were also highest for the "optimal" treatment. Soil uptake of N, P, and K from the unfertilized plots leads to a depletion of these elements, but also very little leaching. Upon addition of N, P, K, Mg, Ca, and S, soil uptake and nutrient accumulation in the soil usually increased at the same time. The high doses of N, P, K, and S in the "optimal" treatment gave a distinct response with higher uptake from the soil and higher accumulation in the soil. No P was leached from the soil, while about one fourth to one third of the applied N, K, and Mg were leached. The treatment induced an unacceptably high nitrate leaching, and must therefore be regarded as "suboptimal".
Forfattere
Erik Lysøe Sonja Klemsdal Karen Rae Bone Rasmus J. N. Frandsen Thomas Johansen U. Thrane Henriette GieseSammendrag
Zearalenones are produced by several Fusarium species and can cause reproductive problems in animals. Some aurofusarin mutants of Fusarium pseudograminearum produce elevated levels of zearalenone (ZON), one of the estrogenic mycotoxins comprising the zearalenones. An analysis of transcripts from polyketide synthase genes identified in the Fusarium graminearum database was carried out for these mutants. PKS4 was the only gene with an enoyl reductase domain that had a higher level of transcription in the aurofusarin mutants than in the wild type. An Agrobacterium tumefaciens-mediated transformation protocol was used to replace the central part of the PKS4 gene with a hygB resistance gene through double homologous recombination in an F. graminearum strain producing a high level of ZON. PCR and Southern analysis of transformants were used to identify isolates with single insertional replacements of PKS4. High-performance liquid chromatography analysis showed that the PKS4 replacement mutant did not produce ZON. Thus, PKS4 encodes an enzyme required for the production of ZON in F. graminearum. Barley root infection studies revealed no alteration in the pathogenicity of the PKS4 mutant compared to the pathogenicity of the wild type. The expression of PKS13, which is located in the same cluster as PKS4, decreased dramatically in the mutant, while transcription of PKS4 was unchanged. This differential expression may indicate that ZON or its derivatives do not regulate expression of PKS4 and that the PKS4-encoded protein or its product stimulates expression of PKS13. Furthermore, both the lack of aurofusarin and ZON influenced the expression of other polyketide synthases, demonstrating that one polyketide can influence the expression of others.
Sammendrag
When conifers such as Picea abies Karst. (Norway spruce) are attacked by insects or pathogens, they often respond by producing increased quantities of terpenoid oleoresin. This response can be mimicked in young P. abies seedlings by treatment with methyl jasmonate (MJ). In this study, we determined the effects of MJ on terpenoids and other chemical defenses of mature P. abies, and investigated whether this treatment protected trees against attack by the blue-stain fungus Ceratocystis polonica (Siem.) C. Moreau, the most important fungal associate of the spruce bark beetle Ips typo-graphus L. Methyljasmonate treatment induced the formation of traumatic resin ducts in the developing xylem, enhanced resin flow and stimulated increased accumulation of monoterpenes, sesquiterpenes and diterpene resin acids. However, only minor changes were detected in terpene composition in response to MJ treatment and no changes in soluble phenolic concentration were measured. There was much variability in the timing and degree of response to MJ among clones. The observed chemical and anatomical changes in response to MJ treatment were correlated with increased resistance to C. polonica, suggesting that terpenoid oleoresin may function in defense against this pathogen.
Sammendrag
Agricultural policy has in the last 50 years taken much of the risk and the initiative away from Norwegian farm forest owners. Subsidies in agriculture have guaranteed an acceptable income and there has been neither need nor incentives for starting up new activities at the farms. This situation is now gradually changing. The income both from agriculture and forestry is decreasing and farm forest owners have either to move, to find job opportunities outside the farm or to start up new activity at the farm using the farm's resources. Entrepreneurship theory is used to study the question why some farm forest owners choose to start up some new activity based on the forest resources they have. We identify two main elements of entrepreneurship; the ability to recognise business opportunities and the ability to take calculated risk. In a survey to 500 forest owners in southern Norway (response rate 45%), we included questions about opportunity recognition and risk aversion. From the answers, we were able to split the forest owners in two groups, those with entrepreneurial attitudes and those without. Using logistic regression we found a significantly higher probability for start-up of new activities in the group with entrepreneurial attitudes. This result has very interesting policy implications. Many studies show that entrepreneurial attitudes to a large degree can be learnt. The first way of learning about entrepreneurship is through the education system and through courses and training of forest owners. The other way is 'learning by doing', which is most probably the most efficient way to learn about entrepreneurship. Public policy should stimulate more owners to 'do', by that they will 'learn' and that will again lead to more entrepreneurial activities at the holdings. (c) 2005 Elsevier B.V. All rights reserved.