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.
2010
Forfattere
Johannes Andre Folkestad Liv Ostrem Jan NetlandSammendrag
Soft rush (Juncus effusus L.) and compact rush (J.conglomeratus L.) have spread significantly in coastal parts of Norway during the past two decades, an increase that seems to have coincided with an observed rise in winter temperatures. This study investigated the effects of exposure to frost on plant regrowth of both species. Exposure to temperatures of -8 to -10°C for more than 6 h resulted in significantly lower regrowth ability compared with non-frozen controls. Regrowth was still observed after 72 h, but with significantly lower regrowth ability for soft rush than for compact rush at 48h and 72 h. These initial results indicate that soft rush is more susceptible to frost than compact rush. However, the species did not differ significantly in frost tolerance.
Sammendrag
Development of ontogenic resistance to powdery mildew (Podosphaera aphanis) on strawberry leaves has been reported, however, the components of resistance have not been elucidated. Five developmental stages of strawberry leaves were identified and assigned numerical values from newly emerged and unexpanded (S1) to fully expanded and dark green (S5) of cvs. Korona and Senga Sengana. The upper and lower surface of the leaves were inoculated from each of the five leaf developmental stages and incubated under controlled conditions. The effect of leaf age on germination, infection efficiency, latency period, and sporulation were later evaluated. All responses were significantly (p = 0.05) affected by leaf age. Germination percentage, infection efficiency, and sporulation were highest, and latent periods were shortest on S1 leaves of both cultivars. On Senga Sengana, germinating conidia produced fewer secondary hyphae during infection. Conidia produced very few secondary hyphae and did not sporulate on S3 leaves, and no infections established on S4 or S5 leaves. The high success of infection and colonization of P. aphanis on S1 leaves indicates that disease is established preferentially on emergent and expanding leaves and these should be the target of management strategies.
Forfattere
Tatsiana Espevig Michelle DaCosta Chenping Xu Lindsey Hoffman Trygve S. Aamlid Anne Marte Tronsmo Bruce B. Clarke Bingru HuangSammendrag
Freezing tolerance is a major component of winter hardiness of perennial grasses. Velvet bentgrass showed the same freezing tolerance as creeping bentgrass. Acclimation at temperatures above 0 ºC was associated with accumulation of nonstructural carbohydrates and enhanced plant survival after freezing. Acclimation at 2 ºC for 4 wk was more effective than for 2 wk and resulted in higher concentrations of fructans. Additional subzero acclimation at -2 ºC resulted in a reduction in fructans and higher concentration of reducing sugars; however, there was no additional improvement in freezing tolerance. Protein analysis was performed using 2-D polyacrylamide gel electrophoresis. Nineteen protein spots were responsive to acclimation. Thirteen proteins were identified. Identified proteins belonged to metabolism, energy, disease/defence, and secondary metabolism functional groups.
Forfattere
Liv Ostrem Arild LarsenSammendrag
Neutral detergent fiber, NDF, and the indigestible part, iNDF, were observed from market cultivars of Festulolium (Hykor, Felopa), Norwegian Festulolium candivars, the parent species perennial ryegrass (Lolium perenne) (cv. Napoleon, 4x), meadow fescue (Festuca pratensis) (cv. Fure) and timothy (Phleum pratense) (cv. Grindstad). Additionally leaf:stem ratio, developmental stage (msc) and total dry matter yield were observed. Field trials for dry matter yield assessment were established in 2006 at Vågønes (67°17"N, 14°27"E), Fureneset (61°34"N, 5°21"E), and Bjørke (60°48"N, 11°12"E) and for forage quality assessment at the two first mentioned locations. Genetic variation was identified for NDF and iNDF at early heading and heading stages between the investigated material. Highest content was found in cv. Hykor whereas in candivars only minor content was observed in leaves, however with higher content in stems. Promising candivars (FuRs0463, FuRs0357) from the Norwegian Festulolium breeding programme revealed better or equal to cultivars of their parental species as to content of NDF and iNDF. Winter survival which is a prerequisite for approved cultivars in Norway, was at an acceptable level in the candivars, and further breeding should preferably continue at the amphitetraploid level of the combination between perennial ryegrass and meadow fescue.
Forfattere
Line JohansenSammendrag
Simultaneously expanding and persistent Trifolium repens patches were studied in a nutrient-poor lawn that was frequently cut. Trifolium repens primary stolon growth strategies were analysed in relation to their location inside the patch, and according to patch size. It was hypothesised that different growth strategies inside a patch can explain a both persistent and expanding patch of Trifolium repens, and that growth strategies were different between patch sizes. The result indicated different growth strategies inside and at the border of patches. Trifolium repens stolons at the border were long, grew fast, had few lateral stolons and grew out of the patch while, stolons inside the patch were smaller, grew slowly, and had more lateral stolons and a wide range of growth directions. Growth strategies were not different between patch sizes. The directional growth and the high growth rate at the border will increase the patch size with time, while the growth strategy near the centre consolidates the patch in space and time, by placing ramets inside the patch. These growth strategies together in a patch result in Trifolium repens patches that are simultaneously persistent and on the increase. The results also indicate a division of labour among primary Trifolium repens stolons in a patch.
Sammendrag
Most fungicide applications targeting apple scab aim to control primary infections caused by ascospores and spraying is thereby linked to ascospore availability. We investigated the effect of pre bud break climatic conditions on seasonal patterns of ascospore release. Apple leaves bearing pseudothecia of Venturia inaequalis were overwintered at orchard sites in 8 countries for up to 3 years. Leaf samples were collected 2 to 5 weeks before bud break and again at bud break, air dried, and sent via airmail to Norway. The samples were stored at -18ºC upon arrival until tested. Disks cut from each replicate leaf sample were incubated moist at 20ºC to allow ascospore maturation but prevent discharge. Matured ascospores were induced to discharge twice a week and enumerated until the supply was exhausted. The proportion of ascospores ejected was fitted against degree-day accumulation using logistic regression. The regression intercept (onset maturation), slope (maturation rate), as well as the absolute number of spores counted differed significantly (P< 0.001, P = 0.05, P< 0.001 respectively) among sites and sampling dates. There was a significant interaction between site and sampling date, indicating that climatic conditions prior to bud break differentially impacted the subsequent ascospore availability. Observed differences could perhaps be used to further refine previously described models of ascospore maturity.
Sammendrag
The leaf blotch disease complex (LBD) frequently reduces yield of wheat in Norway. In visual assessments field symptoms can be difficult to attribute definitively to specific causal agents, and may be caused by any or all of the following three pathogens: Stagonospora nodorum (teleomorph: Phaeosphaeria nodorum) causing Stagonospora nodorum or glume blotch (SNB), Septoria tritici (teleomorph: Mycosphaerella graminicola) causing Septoria tritici or speckled leaf blotch (STB), and Drechslera tritici-repentis (teleomorph: Pyrenophora tritici-repentis) causing tan spot (DTR). There is no broad resistance to all three pathogens in commercially relevant wheat varieties. We analyzed 9 years of historical data on severity of LBD in the field and 36 years of historical data on post-harvest SNB infection of wheat kernels. Overall, correlation between leaf severity and seed severity over years was low (r=0.5). However, during the last 4 years correlations between SNB seed infection and severity of LBD increased (r=0.825). LBD severity varied signficantly with geographic location and increased exponentially on the last 3 leaves betweeen BBCH stage 70 and the last assessment at BBCH stage 89. An improved understanding of environmental and host developmental factors as they affect each member fo the LBD complex in the field will be essential to screening for quantitative and durable resistance to LBD.
Sammendrag
Utviklingen av LED-lamper til vekstbelysning er i full gang, og noen gartnere har allerede begynt å prøve ut lamper med en blanding av rødt og blått lys. For å samle praktisk erfaring med hvordan slike lamper kan påvirke skade- og nyttedyr utførte vi et forsøk i to veksthus med rosesortene "Ingrid Alexandra" og "Passion". Daglengden var 20 timer, og temperaturen var innstilt på 18-19oC med lufting på 23,0-23,5oC. Relativ luftfuktighet var innstilt på 79 %. Det var installert 150 W/m2 med SON-T-lamper (600 W) i veksthusene (150 µmol/m2/s i plantebestandet). Over 3 forsøksruter i hvert veksthus ble det i tillegg til SON-T-lampene hengt opp 2 LED-lamper med en blanding av 80 % rødt (620-630 nm) og 20 % blått (400-500 nm) lys (50-60 µmol/m2/s). Over 3 andre forsøksruter var det bare SON-T lamper. Resultatene viste at det ble fanget mer amerikansk blomstertrips på limfeller og i blomstene under LED-lampene, enn der det bare var SON-T-lampter. De voksne mellusene reagert motsatt av amerikansk blomstertrips, dvs. at det stort sett var mest veksthusmellus på limfellene i forsøksrutene med bare SON-T-lamper. Lampetype så ut til å ha liten effekt på rovmidd (Amblyseius swirskii).
Forfattere
jihong liu clarke Aina-Cathrine Øvergård Even Sannes Riiser Audun H. NerlandSammendrag
Fish nodaviruses (betanodaviruses) are small, non-enveloped icosahedral single-stranded positive-sense RNA viruses that can cause viral encephalopathy and retinopathy (VER) in a number of cultured marine teleost species. The main target organ for NNV infection of fish is the central nervous system (CNS) leading to cellular vacuolation and neuronal degeneration predominantly in larval and juvenile fish, resulting in high mortalities. NNV has been reported to affect around 40 different fish species from all over the world and has been a major limiting factor in the culture of sea bass (L. calcarifer) in India and Atlantic halibut (Hippoglossus hippoglossus) in Norway. The recent finding of VNN affecting farmed Atlantic cod (Gadus morhua) in Norway has caused concern in the aquaculture industry. These observations indicate that the strains are geographically rather than species-related and it is therefore important that vaccines against NNV protect the fish against area-specific strains. Here we report the expression of recombinant nodavirus antigens in tobacco chloroplasts. The vaccine candidates will be evaluated once they have been produced.
Forfattere
Csilla Farkas Giorgio Alberti János Balogh Zoltan Barcza Márta Birkás Szilárd Czóbel Kenneth J Davis Ernõ Führer Györgyi Gelybó Balázs Grosz N Kljun S Koós A Machon H Marjanovic Zlotan Nagy Alessandro Peressotti Krisztina Pintér Eszter Tóth László HorváthSammendrag
Measurement of biosphere-atmosphere exchange of various greenhouse gases requires different techniques. In case of carbon dioxide the net ecosystem exchange (NEE) is usually measured by the eddy covariance method. In the lack of these measurements in forests the carbon dioxide uptake can be estimated by detecting changes in sequestrated carbon stocks or by using tree growth (dendrometric) measurements. The soil CO2, CH4 and N2O efflux/exchange rates can be determined using in situ chamber techniques, or laboratory incubation measurements. Static and dynamic, manual and automatic chamber methods, as well as photo acoustic, gas chromatography and infrared detections can be used for this purpose. This chapter gives a general overview of the approaches applied in studies presented in this book for evaluating the greenhouse gas exchange between the biosphere and atmosphere.