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.
2019
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Ingerd Skow Hofgaard Heidi Udnes Aamot Morten Lillemo Guro Brodal Erik Lysøe Marit Almvik Anne-Grete Roer Hjelkrem Mauritz Åssveen Aina Lundon Russenes Einar Strand Åsmund Bjørnstad Helge Skinnes Selamawit Tekle Espen Sannes Sørensen Trond Buraas Alf Ceplitis Birgitte Henriksen Bernd Rodemann Simon G. EdwardsAbstract
Occasionally, high mycotoxin levels are observed in Norwegian oat grain lots. The development of moderate resistant oat cultivars is therefore highly valued in order to increase the share of high quality grain into the food and feed industry. The Norwegian SafeOats project (2016-2020) aims to develop resistance screening methods to facilitate the phase-out of Fusarium-susceptible oat germplasm. Furthermore, SafeOats will give new insight into the biology of F. langsethiae and HT2+T2 accumulation in oats. The relative ranking of oat varieties according to F. graminearum/DON versus F. langsethiae/HT2+T2 content has been explored in naturally infested as well as in inoculated field trials. Routine testing of the resistance to F. graminearum in oat cultivars and breeding lines has been conducted in Norway since 2007. We are currently working on ways to scale up the inoculum production and fine tune the methodology of F. langsethiae inoculation of field trials to be routinely applied in breeding programs. Through greenhouse studies, we have analysed the content of Fusarium DNA and mycotoxins in grains of selected oat varieties inoculated at different development stages. Furthermore, we are studying the transcriptome during F. langsethiae and F. graminearum infestation of oats. The project also focus on the occurrence of F. langsethiae in oat seeds and possible influence of the fungus on seedling development in a selection of oat varieties. On average, the fungus was observed on 5% of the kernels in 168 seed lots tested during 2016-2018. No indication of transmission of F. langsethiae from germinating seed to seedlings was found in a study with germination of naturally infected seeds. So far, the studies have shown that the ranking of oat varieties according to HT2+T2 content in non-inoculated field trials resembles the ranking observed in inoculated field trials. The ranking of oat varieties according to DON content is similar in non-inoculated and F. graminearum inoculated field trials. However, the ranking of oat varieties according to DON content does not resemble the ranking for HT2+T2. The results from SafeOats will benefit consumers nationally and internationally by providing tools to increase the share of high quality grain into the food and feed industry. The project is financed by The Foundation for Research Levy on Agricultural Products/Agricultural Agreement Research Fund/Research Council of Norway with support from the industry partners Graminor, Lantmännen, Felleskjøpet Agri, Felleskjøpet Rogaland & Agder, Fiskå Mølle Moss, Norgesmøllene, Strand Unikorn/Norgesfôr and Kimen Seed Laboratory.
2018
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Roger Holten Frederik Bøe Marit Almvik Marianne Stenrød Mats Larsbo Nicholas Jarvis Ole Martin EkloAbstract
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Roger Holten Frederik Bøe Marit Almvik Sheela Katuwal Marianne Stenrød Mats Larsbo Nicholas Jarvis Ole Martin EkloAbstract
Limited knowledge and experimental data exist on pesticide leaching through partially frozen soil. The objective of this study was to better understand the complex processes of freezing and thawing and the effects these processes have on water flow and pesticide transport through soil. To achieve this we conducted a soil column irrigation experiment to quantify the transport of a non-reactive tracer and the herbicide MCPA in partially frozen soil. In total 40 intact topsoil and subsoil columns from two agricultural fields with contrasting soil types (silt and loam) in South-East Norway were used in this experiment. MCPA and bromide were applied on top of all columns. Half the columns were then frozen at −3 °C while the other half of the columns were stored at +4 °C. Columns were then subjected to repeated irrigation events at a rate of 5 mm artificial rainwater for 5 h at each event. Each irrigation was followed by 14-day periods of freezing or refrigeration. Percolate was collected and analysed for MCPA and bromide. The results show that nearly 100% more MCPA leached from frozen than unfrozen topsoil columns of Hov silt and Kroer loam soils. Leaching patterns of bromide and MCPA were very similar in frozen columns with high concentrations and clear peaks early in the irrigation process, and with lower concentrations leaching at later stages. Hardly any MCPA leached from unfrozen topsoil columns (0.4–0.5% of applied amount) and concentrations were very low. Bromide showed a different flow pattern indicating a more uniform advective-dispersive transport process in the unfrozen columns with higher con- centrations leaching but without clear concentration peaks. This study documents that pesticides can be pre- ferentially transported through soil macropores at relatively high concentrations in partially frozen soil. These findings indicate, that monitoring programs should include sampling during snow melt or early spring in areas were soil frost is common as this period could imply exposure peaks in groundwater or surface water.
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Freezing and thawing have large effects on water flow in soils since ice may block a large part of the pore space and thereby prevent infiltration and flow through the soil. This, in turn, may have consequences for contaminant transport. For example, transport of solutes contained at or close to the soil surface can be rapidly transported through frozen soils in large pores that were air filled at the time of freezing. Accounting for freezing and thawing could potentially improve model predictions used for risk assessment of contaminant leaching. A few numerical models of water flow through soil accounts for freezing by coupling Richards’ equation and the heat flow equation using of the generalized Clapeyron equation, which relates the capillary pressure to temperature during phase change. However, these models are not applicable to macroporous soils. The objective of this study was to develop and evaluate a dual-permeability approach for simulating water flow in soil under freezing and thawing conditions. To achieve this we extended the widely used MACRO-model for water flow and solute transport in macroporous soil. Richards’ equation and the heat flow equation were loosely coupled using the Clapeyron equation for the soil micropore domain. In accordance with the original MACRO model, capillary forces were neglected for the macropore domain and conductive heat flow in the macropores was not accounted for. Freezing and thawing of macropore water, hence, were solely governed by heat exchange between the pore domains. This exchange included a first-order heat conduction term depending on the temperature difference between domains and the diffusion pathlength (a proxy variable related to the distance between macropores) and convective heat flow. As far as we know, there are no analytical solutions available for water flow during freezing and thawing and laboratory data is limited for evaluation of water flow through macropores. In order to evaluate the new model approach we therefore first compared simulation results of water flows during freezing for the micropore domain to existing literature data. Our model was shown to give similar results as other available models. We then compared the first-order conductive heat exchange during freezing to a full numerical solution of heat conduction. Finally, simulations were run for water flow through frozen soil with initially air-filled macropores for different boundary conditions. Simulation results were sensitive to parameters governing the heat exchange between pore domains for both test cases.