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.
2023
Abstract
No abstract has been registered
Authors
Subal Chandra Kumbhakar Jingfang Zhang Gudbrand LienAbstract
In this study, we leverage geographical coordinates and firm-level panel data to uncover variations in production across different locations. Our approach involves using a semiparametric proxy variable regression estimator, which allows us to define and estimate a customized production function for each firm and its corresponding location. By employing kernel methods, we estimate the nonparametric functions that determine the model’s parameters based on latitude and longitude. Furthermore, our model incorporates productivity components that consider various factors that influence production. Unlike spatially autoregressive-type production functions that assume a uniform technology across all locations, our approach estimates technology and productivity at both the firm and location levels, taking into account their specific characteristics. To handle endogenous regressors, we incorporate a proxy variable identification technique, distinguishing our method from geographically weighted semiparametric regressions. To investigate the heterogeneity in production technology and productivity among Norwegian grain farmers, we apply our model to a sample of farms using panel data spanning from 2001 to 2020. Through this analysis, we provide empirical evidence of regional variations in both technology and productivity among Norwegian grain farmers. Finally, we discuss the suitability of our approach for addressing the heterogeneity in this industry.
Authors
Line Nybakken YeonKyeong Lee Dag Anders Brede Melissa Magerøy Ole Christian Lind Brit Salbu Valerii Kashparov Jorunn Elisabeth OlsenAbstract
The Chernobyl Nuclear Power Plant (ChNPP) accident in 1986 resulted in extremely high levels of acute ionising radiation, that killed or damaged Scots pine (Pinus sylvestris) trees in the surrounding areas. Dead trees were cleared and buried, and new plantations established a few years later. Today, more than three decades later, gamma and beta-radiation near the ChNPP is still elevated compared with ambient levels but have decreased by a factor of 300 and 100, respectively. In the present work, Scots pine-trees growing at High (220 μGy h-1), Medium (11 μGy h-1), and Low (0.2 μGy h-1) total (internal + external) dose rates of chronically elevated ionising radiation in the Chernobyl Exclusion zone were investigated with respect to possible damage to DNA, cells and organelles, as well as potentially increased levels of phenolic and terpenoid antioxidants. Scots pine from the High and Medium radiation sites had elevated levels of DNA damage in shoot tips and needles as shown by the COMET assay, as well as increased numbers of resin ducts and subcellular abnormalities in needles. Needles from the High radiation site showed elevated levels of monoterpenes and condensed tannins compared with those from the other sites. In conclusion, more than three decades after the ChNPP accident substantial DNA damage and (sub)cellular effects, but also mobilisation of stress-protective substances possessing antioxidant activity were observed in Scots pine trees growing at elevated levels of ionising radiation. This demonstrates that the radiation levels in the Red Forest still significantly impact the plant community.
Authors
Line Nybakken YeonKyeong Lee Dag Anders Brede Melissa Magerøy Ole Christian Lind Brit Salbu Valerii Kashparov Jorunn Elisabeth OlsenAbstract
The Chernobyl Nuclear Power Plant (ChNPP) accident in 1986 resulted in extremely high levels of acute ionising radiation, that killed or damaged Scots pine (Pinus sylvestris) trees in the surrounding areas. Dead trees were cleared and buried, and new plantations established a few years later. Today, more than three decades later, gamma and beta-radiation near the ChNPP is still elevated compared with ambient levels but have decreased by a factor of 300 and 100, respectively. In the present work, Scots pine-trees growing at High (220 μGy h−1), Medium (11 μGy h−1), and Low (0.2 μGy h−1) total (internal + external) dose rates of chronically elevated ionising radiation in the Chernobyl Exclusion zone were investigated with respect to possible damage to DNA, cells and organelles, as well as potentially increased levels of phenolic and terpenoid antioxidants. Scots pine from the High and Medium radiation sites had elevated levels of DNA damage in shoot tips and needles as shown by the COMET assay, as well as increased numbers of resin ducts and subcellular abnormalities in needles. Needles from the High radiation site showed elevated levels of monoterpenes and condensed tannins compared with those from the other sites. In conclusion, more than three decades after the ChNPP accident substantial DNA damage and (sub)cellular effects, but also mobilisation of stress-protective substances possessing antioxidant activity were observed in Scots pine trees growing at elevated levels of ionising radiation. This demonstrates that the radiation levels in the Red Forest still significantly impact the plant community.
Authors
Samuel W. Wilkinson Adam Hannan Parker Amos Muench Robert Simon Wilson K. Hooshmand M.A. Henderson Emma K. Moffat P.S.C.F. Rocha H. Hipperson J.H.M. Stassen Ana López Sánchez Inge S. Fomsgaard Paal Krokene Melissa Magerøy Jurriaan TonAbstract
Stress can have long-lasting impacts on plants. Here we report the long-term effects of the stress hormone jasmonic acid (JA) on the defence phenotype, transcriptome and DNA methylome of Arabidopsis. Three weeks after transient JA signalling, 5-week-old plants retained induced resistance (IR) against herbivory but showed increased susceptibility to pathogens. Transcriptome analysis revealed long-term priming and/or upregulation of JA-dependent defence genes but repression of ethylene- and salicylic acid-dependent genes. Long-term JA-IR was associated with shifts in glucosinolate composition and required MYC2/3/4 transcription factors, RNA-directed DNA methylation, the DNA demethylase ROS1 and the small RNA (sRNA)-binding protein AGO1. Although methylome analysis did not reveal consistent changes in DNA methylation near MYC2/3/4-controlled genes, JA-treated plants were specifically enriched with hypomethylated ATREP2 transposable elements (TEs). Epigenomic characterization of mutants and transgenic lines revealed that ATREP2 TEs are regulated by RdDM and ROS1 and produce 21 nt sRNAs that bind to nuclear AGO1. Since ATREP2 TEs are enriched with sequences from IR-related defence genes, our results suggest that AGO1-associated sRNAs from hypomethylated ATREP2 TEs trans-regulate long-lasting memory of JA-dependent immunity.
Authors
Isabell EischeidAbstract
No abstract has been registered
Abstract
More than 2/3rds of Norway’s agricultural area are grassland, and more than half of it is over 5 years old. Renewing old grassland increases annual yield but causes yield loss during renewal. Parts of the increased yield is due to replacement of low-productive species with high production species and cultivars, replacing biodiversity with productivity. Finding the optimal rate of renewal requires long term experiments to compare the sustainability of different strategies. Therefore, three field experiments were established to investigate the effect of difference renewal and harvest strategies on grass yield and quality, on similar mineral soil at Særheim (58.5°N, 5.6°E) in 1968 and Fureneset (61.3°N,5.0°E) in 1974, and on peat soil at Svanhovd (69.5°N,30.0°E) in 1968. Until 1991, the experiment included non-renewed treatments, and renewal every 3rd or 6th year. It was cut either two or three times a year, with autumn grazing on parts of the two-cut regime. The experiment was simplified in 1992, with the establishment of another non-renewed treatment, all treatments being cut 3 times a year (2 at Svanhovd), no grazing but contrasting slurry and compound fertilizer applications. This phase lasted until 2011, followed by period with no renewal and minimal registration. The third phase started in 2016, with renewal of all treatments at Fureneset and Særheim, except the permanent grassland from 1968/1974. Duration between renewals was doubled, and fertilizer applications revised. Presenting results from the third phase, we show that five to six years are required to recoup and significantly over-yield the non-renewed grassland. We will use soil chemical and physical properties, fertilizer application and yield gaps as well as ecological succession from sown seed mixture in 2017 till 2022 grassland to discuss the why we needed six years for all renewed treatments to over-yield permanent grassland from 1974.
Authors
Jian LiuAbstract
No abstract has been registered
Authors
Arne Verstraeten Peter Waldner Aldo Marchetto Andreas Schmitz Nicholas Clarke Anne Thimonier Catherine Hilgers Anne-Katrin Prescher Karin HansenAbstract
No abstract has been registered
Authors
Ludmila Sromek Eeva Ylinen Mervi Kunnasranta Simo Maduna Tuula Sinisalo Craig T. Michell Kit M. Kovacs Christian Lydersen Evgeny Ieshko Elena Andrievskaya Vyacheslav Alexeev Sonja Leidenberger Snorre Hagen Tommi NymanAbstract
Studies on host–parasite systems that have experienced distributional shifts, range fragmentation, and population declines in the past can provide information regarding how parasite community richness and genetic diversity will change as a result of anthropogenic environmental changes in the future. Here, we studied how sequential postglacial colonization, shifts in habitat, and reduced host population sizes have influenced species richness and genetic diversity of Corynosoma (Acanthocephala: Polymorphidae) parasites in northern European marine, brackish, and freshwater seal populations. We collected Corynosoma population samples from Arctic, Baltic, Ladoga, and Saimaa ringed seal subspecies and Baltic gray seals, and then applied COI barcoding and triple-enzyme restriction-site associated DNA (3RAD) sequencing to delimit species, clarify their distributions and community structures, and elucidate patterns of intraspecific gene flow and genetic diversity. Our results showed that Corynosoma species diversity reflected host colonization histories and population sizes, with four species being present in the Arctic, three in the Baltic Sea, two in Lake Ladoga, and only one in Lake Saimaa. We found statistically significant population-genetic differentiation within all three Corynosoma species that occur in more than one seal (sub)species. Genetic diversity tended to be high in Corynosoma populations originating from Arctic ringed seals and low in the landlocked populations. Our results indicate that acanthocephalan communities in landlocked seal populations are impoverished with respect to both species and intraspecific genetic diversity. Interestingly, the loss of genetic diversity within Corynosoma species seems to have been less drastic than in their seal hosts, possibly due to their large local effective population sizes resulting from high infection intensities and effective intra-host population mixing. Our study highlights the utility of genomic methods in investigations of community composition and genetic diversity of understudied parasites.