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.
2009
Authors
Karl ThunesAbstract
Det er ikke registrert sammendrag
Abstract
Introduction: Current risk assessment procedures for contaminated land and for pesticides often fail to properly characterize the risk of chemicals for environment or human health and provide only a rough estimate of the potential risk of chemicals. Chemicals often occur in mixtures in the environment, while regulatory agencies often use a chemical-by-chemical approach, focusing on a single media, a single source, and a single toxic endpoint. Current concepts to estimate biological effects of chemical mixtures mainly rely on data available for single chemicals, disregarding interaction between chemicals in soils. The importance of soil microbes and their activity in the functioning of soils impose a need to include microorganisms in soil quality assessments (Winding et al., 2005) including terrestrial ecotoxicological studies. Numerous papers have been published on the effects of different contaminants on soil microbes, establishing changes in soil microbial diversity as an indicator of soil pollution, but only a limited number of molecular studies investigating fungal diversity in the environment have been performed. The main objective of the study presented here, is to assess the applicability of changes in soil microbial diversity and activity levels as indicators of ecologically relevant effects of chemicals contamination. We have studied the effects of the fungicide picoxystrobin and the chemical 4-n-nonylphenol, on the microbial biodiversity in a Norwegian sandy loam with focus both on prokaryotes and the fungal species. 4-n-nonylphenol is a chemical occurring in high amounts in sewage sludge, hence, these chemicals may occur as single chemicals as well as in mixtures in soils. This work is part of the research project ‘Bioavailability and biological effects of chemicals - Novel tools in risk assessment of mixtures in agricultural and contaminated soils" funded by the Norwegian research council.Methods: Soil samples were treated with the single chemicals or mixtures and incubated at 20°C. Continuous monitoring of respiration activity as well as occasional destructive sampling for extraction of soil DNA, RNA, and chemical residues was performed through a 70 d period. Amplification of soil bacterial and fungal DNA was followed by T-RFLP analysis to assess chemicals effects on soil microbial diversity. Further work will include analyses of extracted soil RNA to assess chemicals effects on important soil functions (e.g. nitrogen cycling, decomposition of organic matter) and an assessment of chemicals effects on the genetic diversity of the soil by high throughput shot-gun sequencing. Finally the results will be evaluated to assess the suitability of any specific group, species or activity/function as biomarker for the selected chemicals (and possibly their group of chemicals).Results and conclusions: A project outline and preliminary results from the project will be presented at the conference.ReferencesWinding A, Hund-Rinke K, Rutgers M (2005). The use of microorganisms in ecological soil classification and assessment concepts. Ecotoxicology and Environmental Safety 62: 230-248.
Abstract
Control of dock species are a true bottleneck in the development of grassland based organic forage production in Norway. Rumex obtusifolius, Rumex crispus and Rumex longifolius are among the most important perennial weeds in grassland areas throughout the world. These dock- species are undesired in grasslands because they decrease yields and reduce forage feeding value. The experiment in our study is carried out as a full-factorial design, including key-factors, which may influence dock behaviour significantly. The first factor, (i) date of grassland establishment, may be important for preventing /decreasing the flush of seedlings from seeds as well as shoots from root fragments. The purpose of the second factor, (ii) black fallow, is both false seedbed preparation and decreasing food reserves in underground plant parts. The third factor, (iii) is the use of equipment for cutting the taproot either (a) before ploughing by using a tractor propelled rotovator, or (b) cutting the dock taproot in the same operation as ploughing by using a prototype ¿two layer dockplough¿. The biological background for cutting the taproot before ploughing is that many studies have shown that new shoots only come from the 5 upper cm of the taproot. Furthermore, our hypothesis is that shoots from highly fragmented regenerative parts (the neck) of the taproot placed deep will not reach the soil surface before their reserves are depleted. Experiments were carried out at 3 and 4 locations in 2007 and 2008, respectively. Weed development were assessed as number of emerging seedlings as well as number of sprouting plants from root fragments, both in the year when the treatments were carried out and the following year. The results are yet not completely analyzed, but preliminary results indicate that plants from seeds frequently are more numerous than plants from roots. At least at some locations and years both the use of rotovator and the ¿dock plough¿, has reduced the number of plants from root fragments with approx. 50%. However, our experiments have shown that ¿dock plough¿ prototype has to be improved, especially because it did not cut the taproot near the open furrow, and did not bury the green parts well enough.
Authors
Ingerd Skow Hofgaard Katarzyna Marzec Guro Brodal Birgitte Henriksen May Bente Brurberg Anne-Marte TronsmoAbstract
Microdochium nivale (syn. Microdochium nivale var. nivale) and Microdochium majus (syn. Microdochium nivale var. majus) are important pathogens which cause snow mould on grasses and winter cereals. These fungi are also able to cause leaf blotch of oat and seedling blight, foot rot and ear blight in cereals. Although no distinct differences in the host range of M. nivale and M. majus are found, indications for differences in host preferences between these fungal species have previously been discussed. The culture collection at Bioforsk contains about 250 Microdochium sp. isolated from grasses and cereals over the last 20 years. Most of the isolates collected from leaves of cereals displaying snow mould symptoms in spring, were identified as M. nivale (71 %), whereas most of the isolates collected from cereal seeds (mostly wheat) belong to the species M. majus (92 %). All, except one out of the sixty nine Microdochium sp. isolated from grass leaves were identified as M. nivale (99 %). The relatively higher incidence of M. majus vs. M. nivale on cereal seeds (mostly wheat) harvested in Norway, is in agreement with studies in UK (Parry et al. 1995). Parry et al. suggested that higher natural occurrence of M. majus (vs. M. nivale) on seeds of cereals could be partly due to the higher proportion of M. majus isolates producing perithecia and thus, a relatively higher amount of M. majus spores spreading to the ear (Parry et al. 1995). The high frequency of M. nivale (99 %) vs. M. majus on grasses collected in Norway could indicate that M. nivale is more aggressive on certain grass species. Studies in our lab indeed point towards a higher aggressiveness of M. nivale vs. M. majus on perennial ryegrass at low temperature (2?C) (Hofgaard et al 2006). However, the high incidence of M. nivale on grass leaves could also be caused by differences in temperature preferences, saprophytic ability or ability to infect certain plant parts. Isolates of M. nivale display a higher in vitro growth rate compared to isolates of M. majus at 2?C (Hofgaard et al. 2006). In conclusion, the higher natural occurrence of M. nivale vs. M. majus on turf grasses and the relatively higher aggressiveness of M. nivale on perennial ryegrass could indicate that M. nivale somehow is better adapted to infect certain grass species.
Authors
Belachew Asalf Tadesse Arne Stensvand David M. Gadoury Robert C Seem Andrew Dobson Anne-Marte TronsmoAbstract
Development of ontogenic resistance to powdery mildew (Podosphaera aphanis) in strawberry fruit has not been quantified, and thus cannot be exploited in disease management programs. Four commercially-relevant strawberry cultivars were evaluated for ontogenic resistance to powdery mildew. Fruits were inoculated at one of the four growth stages: flowering, green, white and early pink fruit. There was a significant difference between and within cultivars at the bloom and green stage of inoculations (P <0.05) for both disease incidence and severity. On average 16.4, 39.5, 48.7, and 60.3 % of the fruits inoculated at bloom developed powdery mildew in cultivars Elan, Korona, Frida and Inga, respectively. None of the cultivars developed powdery mildew when inoculated at the pink stage. It may be concluded that flowers and green fruits of strawberry were much more susceptible to powdery mildew infection than white and pink fruits. The high susceptibility of cultivars at the flower and early green stages seemed coincident with the succulent nature of the fruits at these stages, making it easy for penetration and establishment of mildew. Control measures targeting at these critical windows of fruit susceptibility are likely to reduce yield loss.
Abstract
Det er ikke registrert sammendrag
Abstract
Det er ikke registrert sammendrag
Abstract
Det er ikke registrert sammendrag
Authors
B. Kronvang H. Behrendt H. E. Andersen B. Arheimer A. Barr Stig A. Borgvang F. Bouraoui K. Granlund B. Grizzetti P. Groenendijk E. Schwaiger J. Hejzlar L. Hoffmann H. Johnsson Y. Panagopoulos A. Lo Porto H. Reisser O. Schoumans S. Anthony M. Silgram M. Venohr S. E. LarsenAbstract
Det er ikke registrert sammendrag
Abstract
Det er ikke registrert sammendrag