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.
2024
Abstract
Tip rot of carrot significantly reduces root quality and contributes to the high-level rejection during sorting and packaging in Norway. The rot can be dry, or wet, and vary in colour from light brown to dark brown. Diagnosis of a plant disease involves close examination of the symptoms, detection and identification of the causal agent(s), and confirmation of pathogenicity. The objective of this study was to identify the causal agent(s) of tip rot in carrot. Fungi and bacteria were isolated from multiple carrots with tip rot symptoms and used for inoculation of healthy carrots to determine pathogenicity and also for DNA extraction, sequencing of commonly used genes for identification and barcoding genes and DNA metabarcoding. For isolation and inoculation, we developed a method allowing individual carrots to remain upright without touching each other within an incubation box. For morphological identification of causal agents, we found that a combination of methods such as isolation on potato carrot agar, disinfection of infected tissue followed by moist incubation, and inoculation followed by incubation at room temperature for 24 h, and then at 0-6°C were optimal methods for the identification of tip rot pathogens of carrot. Based on the combination of molecular and morphological identification methods, we found that tip rot of carrots is a disease complex caused by several fungi but principally Mycocentrospora acerina and Cylindrocarpon destructans. Diagnosis of postharvest diseases is often a complex problem, and this research demonstrates that a combination of methods is a useful approach. Furthermore, the study indicated that the common approach of trying to associate a disease with a single causal agent does not work for all postharvest diseases. The possibility of multiple causal agents and predisposing factors must be considered, and we should be cautious not to jump to a hasty decision.
Authors
Guro BrodalAbstract
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Melissa MagerøyAbstract
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Melissa MagerøyAbstract
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Mingkai Jiang Kristine Y. Crous Yolima Carrillo Catriona A. Macdonald Ian C. Anderson Matthias M. Boer Mark Farrell Andrew N. Gherlenda Laura Castañeda-Gómez Shun Hasegawa Klaus Jarosch Paul J. Milham Rául Ochoa-Hueso Varsha Pathare Johanna Pihlblad Juan Piñeiro Jeff R. Powell Sally A. Power Peter B. Reich Markus Riegler Sönke Zaehle Benjamin Smith Belinda E. Medlyn David S. EllsworthAbstract
The capacity for terrestrial ecosystems to sequester additional carbon (C) with rising CO2 concentrations depends on soil nutrient availability1,2. Previous evidence suggested that mature forests growing on phosphorus (P)-deprived soils had limited capacity to sequester extra biomass under elevated CO2 (refs. 3,4,5,6), but uncertainty about ecosystem P cycling and its CO2 response represents a crucial bottleneck for mechanistic prediction of the land C sink under climate change7. Here, by compiling the first comprehensive P budget for a P-limited mature forest exposed to elevated CO2, we show a high likelihood that P captured by soil microorganisms constrains ecosystem P recycling and availability for plant uptake. Trees used P efficiently, but microbial pre-emption of mineralized soil P seemed to limit the capacity of trees for increased P uptake and assimilation under elevated CO2 and, therefore, their capacity to sequester extra C. Plant strategies to stimulate microbial P cycling and plant P uptake, such as increasing rhizosphere C release to soil, will probably be necessary for P-limited forests to increase C capture into new biomass. Our results identify the key mechanisms by which P availability limits CO2 fertilization of tree growth and will guide the development of Earth system models to predict future long-term C storage.
Authors
Carl Frisk Godfrey Philliam Apangu Geoffrey M. Petch Simon Creer Mary Hanson Beverley Adams-Groom Carsten Ambelas SkjøthAbstract
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Authors
Kim Viggo Paulsen Weiby Margrete Eknæs Angela Schwarm Håvard Steinshamn Karen Beauchemin Peter Lund Ingunn Schei Ingjerd DønnemAbstract
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Authors
Kim Viggo Paulsen Weiby Linda Årvik Margrete Eknæs Angela Schwarm Håvard Steinshamn K.A. Beauchemin Peter Lund Ingunn Schei Ingjerd DønnemAbstract
The aim of this study was to examine how silages from different grassland species and harvesting frequencies affect feed intake, milk production, and methane (CH4) emission in dairy cows. We hypothesized that cows consuming silages of more frequent harvest, grass species with greater organic matter digestibility and legumes with lower NDFom concentration would have greater silage dry matter intake and milk yield and thereby lower CH4 yield and intensity. Forty Norwegian Red cows were allocated to 5 treatments in a cyclic changeover design with 4 21-d periods (14 d of adaptation, 7 d of data collection). The 5 treatments evaluated were silages produced from timothy (Phleum pratense L.) in a 3-cut system (T3), timothy in a 2-cut system (T2), perennial ryegrass (Lolium perenne L.) in a 3-cut system (PR3), red clover (Trifolium pratense L.) in a 3-cut system (RC3) and a mix of T3 and RC3 (50:50 on DM basis) (T3/RC3). The treatments were prepared by mixing silages from each crop over the growing season, proportional to the harvested DM yield of each cut. Cows were offered the mixed silages ad libitum supplemented with a fixed level of concentrate. Gas emissions were measured using 2 Greenfeed units. Milk yield was recorded in the milking robot at each visit, and milk samples were collected at 3 consecutive milkings during the last 7 d of each period. Cows were weighed after each milking, and total-tract digestibility of each diet was estimated using acid insoluble ash as internal marker in fecal grab samples. The data were analyzed using the MIXED procedure of SAS with block, period and treatment as fixed effects and animal within block as random effect. Silage and total DMI did not differ between T3 and T2, but total DMI was lower for PR3 than for T3. There was a quadratic effect of increased proportion of red clover, with highest intakes of T3/RC3 and lower intakes of RC3 than of T3. Energy corrected milk (ECM) yield was lower for T2 than T3, and for PR3 than T3. There was a quadratic effect of increased proportion of red clover, with highest ECM yield in T3/RC3 and lower in RC3 than in T3. Organic matter digestibility was lower for T2 than T3, but it did not differ between T3 and PR3. Including red clover in the diet linearly decreased organic matter digestibility. Methane production (g/d) did not differ between T3 and T2, but CH4 intensity (g/kg ECM) was greater for T2 than for T3. There was no difference between T3 and PR3 for CH4 production but yield and intensity were greater for PR3 than T3. Including red clover in the diet linearly increased CH4 production, yield and intensity with greatest intensity in the 100% red clover diet. In conclusion, changing harvesting frequency for timothy from 2 to 3 harvests per year did not affect CH4 production or yield, but CH4 intensity was reduced. Replacing timothy with perennial ryegrass and increased inclusion rate of red clover both increased CH4 yield and intensity.
Abstract
Manures are potentially both a source of nutrients for plants and a source of pollution. Manure produced depends on animal densities and type rather than plants need. Over time, this has enriched soils with P and organic N. The challenge is maximal nutrient recycling and minimal pollution from the manure used for plant production. To investigate the optimal seasonal distribution of manure, field experiments were carried out in 2022 and 2023 on grassland in three agricultural regions in Norway. Three distributions of cattle slurry at 30 kg P ha–1 were tested, with or without additional N fertilizer. These were compared with control treatments without slurry: no fertilizer, and compound NPK and NK fertilizers. Different distributions had little effect on grass yield and uptake of P and N. Applying a larger proportion of manure in spring increased grass yield, while additional mineral N fertilizer significantly increased yield but reduced N use efficiency. Slurry alone gave a P surplus, while added mineral N fertilizer allowed a net mining of P. There seems therefore to be a trade-off regarding whether the efficient use of N or P is to be prioritized. The decision should likely depend on required yields as well as local pollution risks.