Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2017
Authors
Trygve S. Aamlid Wendy Marie Waalen Pia Heltoft Thomsen Tatsiana Espevig Agnar Kvalbein Gudni Thorvaldsson A. M. D. JensenAbstract
No abstract has been registered
Abstract
During August 2013, white-grayish lesions, typical of Sclerotinia stem rot, had developed around leaf axils on the stems of turnip rape ‘Pepita’ in a field at the NIBIO research station Apelsvoll in Oppland County, Norway. Sclerotia were collected from inside infected turnip rape stubble and from harvested seeds, surface sterilized, bisected, and placed onto potato dextrose agar (PDA). Following 1 to 2 days incubation at 20°C, fast-growing white mycelium characteristic of Sclerotinia was observed, and within 5 to 7 days, new sclerotia had started to develop. Sclerotia size and growing pattern although variable was characteristic of S. sclerotiorum. DNA extraction, PCR amplification, and sequencing of the ITS regions of the rDNA was then carried out for 20 isolates. BLASTn analysis of 475 bp amplicons showed that 15 isolates were S. sclerotiorum, while five were identified as S. subarctica (previously called Sclerotinia sp 1; Holst-Jensen et al. 1998; Winton et al. 2006, 2007), with 100% identity to a U.K. S. subarctica isolate (Clarkson et al. 2010). A representative ITS region sequence was deposited in GenBank (accession no. KX929095). The identity of the S. subarctica isolates was further confirmed by the lack of a 304-bp intron in the LSU rDNA compared with S. sclerotiorum (Holst-Jensen et al. 1998), which was visualized by PCR amplification and gel electrophoresis. Sclerotia of two S. subarctica isolates were placed on PDA and incubated for 7 days. Agar plugs of actively growing mycelium were used for the pathogenicity testing of spring oilseed rape plants (‘Mosaik’) in the greenhouse. Plants were inoculated at growth stage BBCH 57/59 (preflowering) and BBCH 64 (40% of flowers open) by attaching two PDA plugs of actively growing mycelium per main stems with small needles, using four plants per treatment. Noninoculated PDA agar plugs were attached to the control plants. The experiment was repeated three times. Symptoms typical of stem rot appeared after 1 to 2 weeks of incubation at 16 to 20°C, 100% relative humidity. Stems started to develop white lesions with fluffy mycelium around the inoculation sites. Control plants did not show the characteristic symptoms for Sclerotinia infection. After senescence of the plants, sclerotia were collected from inside the stems and cultured on PDA. White mycelium started to grow after 1 to 2 days and new sclerotia were formed within 7 days, similar to the ones used for producing the initial isolate. Brassica oil seed crops are cultivated as important break crops in the cereal-based production system in Norway and can be severely affected by Sclerotinia stem rot. The disease is observed in all regions where Brassica oil seed crops are grown, and in severe cases, a reduction in oilseed yield of 25% has been recorded in untreated control treatments of fungicide trials. Although S. subarctica has been previously reported on wild hosts (Holst-Jensen et al. 1998), this is the first report of the pathogen on a crop plant in Norway. In the United Kingdom, Clarkson et al. (2010) demonstrated pathogenicity of S. subarctica isolated from Ranunculus acris on oilseed rape. As symptoms for S. subarctica and S. sclerotiorum are indistinguishable, S. subarctica might be present undetected in many farmer fields.
Abstract
No abstract has been registered
Abstract
To predict how the function of urban vegetation and the provision of ecosystem services respond to combinations of natural and anthropogenic drivers, a better understanding of multiple stress interactions is required. This study tested combined effects of moderate levels of drought, soil salinity and exposure to diesel exhaust on parameters of physiology, metabolism, morphology and growth of Pinus sylvestris L. saplings. We found that plant responses were primarily dominated by single stressors and a few two-way interactions. Stressor combinations did not have considerable additional negative effects on plant performance compared to single stressors. Hence, synergistic and antagonistic interactions were rare and additive effects frequent. Drought cycles caused most negative effects, from chlorophyll a fluorescence and epicuticular wax content to growth responses, while soil salinity caused fewer negative effects but contributed to reduction in fine root growth and fluorescence parameters at low air contamination. Interestingly, the air contamination alone had only marginal effects on plant morphology and growth, but contributed an antagonistic effect, dampening the negative effect of drought and salinity on the maximum quantum efficiency of PSII photochemistry (Fv/Fm) and fine root biomass. Although, these effects were moderate, it appears that exhaust exposure had a cross-acclimation effect on plant responses to drought and salinity. We also found that salinity had a negative effect on the accumulation of particulate matter on shoots, illustrating that the plant stress situation can affect the provisioning of certain ecosystem services like pollution attenuation. These findings have implications for the understanding of the complex natural and anthropogenic stress situation of urban, and how to maintain the ecological functions and delivery of ecosystem services.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Area-efficient constructed systems for stormwater management and bioretention may involve large fluc-tuations in subsurface water levels. Such fluctuations challenge vegetation by forcing roots to exploredeeper layers to access water during dry periods. In a controlled experiment, we studied growth pat-terns and the ability of Phragmites australis roots to track subsurface water level fluctuations of differingamplitude and frequency in substrates with contrasting water-holding capacity. We found that P. aus-tralis was able to adjust its rooting pattern to considerable subsurface water level fluctuations (to wellbelow 120 cm), but that substrate characteristics can restrict its ability to adjust to larger fluctuations.Fluctuation amplitude was the driving factor for plant growth and biomass allocation responses, whilesubstrate characteristics and fluctuation frequency were less important. When not exposed to large waterlevel fluctuations, P. australis grew larger shoots and only explored intermediate rooting depths. Therewas a negative relationship between root and rhizome biomass, showing a resource-based trade-off andshort-term costs of adjusting rooting patterns to large water level fluctuations. These results indicatethat P. australis is suited for systems with considerable subsurface water fluctuations, but constraints onits flexibility need to be investigated.
Abstract
Application of fish sludge as fertiliser to agricultural land can contribute to closing nutrient cycles in fish farming. The effect of different treatment technologies on the nitrogen fertilisation effects of fish sludge was studied by a bioassay with barley (Hordeum vulgare), an incubation and a field experiment. Dried fish sludge resulted in relative agronomic efficiency of 50–80% compared with mineral fertiliser. The anaerobic digestate based on fish sludge (20 vol%) and dairy manure did not increase nitrogen uptake in barley. Increasing the ratio of fish sludge in the digestate increased the fertilisation effect, but requires optimisation of the biogas process. A simple logistics analysis conducted for a case hatchery showed that on-site drying and co-digestion of fish sludge in a central biogas plant can be regarded as equal in terms of costs. Norway can become an exporter of fish sludge-based recycling fertilisers if current regulations are modified to facilitate nutrient recycling.
Authors
Marianne Stenrød Therese With Berge Ole Martin Eklo Alexander Melvold Engebretsen Andrea Ficke Valborg Kvakkestad Roar Lågbu Anne Prestvik Karen Refsgaard Divina Gracia P. Rodrigues Eivind Solbakken Jörn Strassemeyer Kirsten Tørresen Anne Falk ØgaardAbstract
No abstract has been registered
Abstract
No abstract has been registered