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.
2016
Authors
Katja Karppinen Laura Zoratti Marian Sarala Elisabete Carvalho Jenni Hirsimäki Helmi Mentula Stefan Martens Hely Häggman Laura JaakolaAbstract
This is an open access article distributed under the terms of the <a href="https://creativecommons.org/licenses/by/4.0/"> Creative Commons Attribution License</a>, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. <br> This article is also available via DOI:<a href="http://dx.doi.org/10.1186/s12870-016-0785-5">10.1186/s12870-016-0785-5</a>
Abstract
Two new species of Schistidium are described from Asian Russia. Their distinctness is supported by nrDNA ITS1-2 sequence data. S. austrosibiricum was not previously differentiated from S. sinensi- apocarpum, mainly due to their similarly long and sharply serrate hair-points in stem and perichaetial leaves and papillose dorsal side of costa. However, they differ in leaf size and shape, hair-points flatness and leaf lamina areolation. S. austrosibiricum is known from southernmost mountain areas of Asian Russia, while S. sinensiapocarpum is a widespread circumholarctic montane species. The sec- ond species, S. scabripilum is morphologically similar to S. echinatum, and some specimens were previously referred to it. The main differences between them concern hair-point length and structure, including length of protruding spinulae and their angle with the hair-point axis. However, they belong to different clades in the molecular phylogenetic tree and possess different distribution patterns. S. scabripilum is a northern Asian species, found in the Putorana Plateau, southern Taimyr, Yakutia and Chukotka, while S. echinatum is known from the Alps, Caucasus and Ural mountains, and in western North America. Description, illustrations, distribution and ecological data are provided for the new species, and comparison with similar species is given.
Authors
Pia Heltoft Thomsen May Bente Brurberg Monica Skogen Vinh Hong Le Jafar Razzaghian Arne HermansenAbstract
The prevalence of Fusarium dry rot in potatoes produced in Norway was investigated in a survey for three consecutive years in the period 2010 to 2012. A total of 238 samples (comprising 23,800 tubers) were collected, representing different cultivars and production regions in Norway. Fusarium spp. were detected in 47% of the samples, with one to three species per sample. In total, 718 isolates of Fusarium spp. were recovered and identified to seven species. The most commonly isolated species was Fusarium coeruleum, comprising 59.6% of the total Fusarium isolates and found in 17.2% of the collected samples, followed by Fusarium avenaceum (27.2% of the isolates and found in 27.7% of the samples). Fusarium sambucinum was the third most prevalent species (6.4% in 8.8% of the samples) and Fusarium culmorum the fourth (5.2% in 6.3% of the samples). Less prevalent species included Fusarium cerealis, Fusarium graminearum, and Fusarium equiseti (<1% in 0.4 to 1.3% of the samples). F. coeruleum was the most prevalent species in northern and southwestern Norway, whereas F. avenaceum was dominating in eastern Norway. The potato cultivars Berber and Rutt were susceptible to all Fusarium spp. A new TaqMan real-time PCR assay specific for F. coeruleum was developed, which successfully identified Norwegian isolates. This and other previously developed real-time PCR assays targeting different Fusarium species were evaluated for their ability to detect latent infections in potatoes at harvest. This study provides new information on the current occurrence of different Fusarium species causing Fusarium dry rot in potatoes in Europe including areas far into the arctic in the north of Norway.
Authors
Hadush Tsehaye Beyene May Bente Brurberg Leif Sundheim Dereje Assefa Arne Tronsmo Anne Marte TronsmoAbstract
Fusarium species causing maize kernel rot are major threats to maize production, due to reduction in yield as well as contamination of kernels by mycotoxins that poses a health risk to humans and animals. Two-hundred maize kernel samples, collected from 20 major maize growing areas in Ethiopia were analyzed for the identity, species composition and prevalence of Fusarium species and fumonisin contamination. On average, 38 % (range: 16 to 68 %) of maize kernels were found to be contaminated by different fungal species. Total of eleven Fusarium spp. were identified based on morphological characteristics and by sequencing the partial region of translation elongation factor 1-alpha (EF-1α) gene. Fusarium verticillioides was the dominant species associated with maize kernels (42 %), followed by F. graminearum species complex (22.5 %) and F. pseudoanthophilium (13.4 %). The species composition and prevalence of Fusarium species differed among the areas investigated. Fusarium species composition was as many as eight and as few as four in some growing area. The majority of the maize samples (77 %) were found positive for fumonisin, with concentrations ranging from 25 μg kg−1 to 4500 μg kg−1 (mean: 348 μg kg−1 and median: 258 μg kg−1). Slight variation in fumonisin concentration was also observed among areas. Overall results indicate widespread occurrence of several Fusarium species and contamination by fumonisin mycotoxins. These findings are useful for intervention measures to reduce the impact of the main fungal species and their associated mycotoxins, by creating awareness and implementation of good agricultural practices.
Authors
Gisela Lüscher Youssef Ammari Aljona Andriets Siyka Angelova Michaela Arndorfer Debra Bailey Katalin Balázs Marion Bogers R.G.H. Bunce Jean-Philippe Choisis Peter Dennis Mario Díaz Tetyana Dyman Sebastian Eiter Wendy FjellstadAbstract
No abstract has been registered
Authors
Sabine Rosner Jan Světlík Kjell Andreassen Isabella Børja Lise Dalsgaard Robert Evans Saskia Luss Ole Einar Tveito Svein SolbergAbstract
Top dieback in 40–60 years old forest stands of Norway spruce [Picea abies (L.) Karst.] in southern Norway is supposed to be associated with climatic extremes. Our intention was to learn more about the processes related to top dieback and in particular about the plasticity of possible predisposing factors. We aimed at (i) developing proxies for P50 based on anatomical data assessed by SilviScan technology and (ii) testing these proxies for their plasticity regarding climate, in order to (iii) analyze annual variations of hydraulic proxies of healthy looking trees and trees with top dieback upon their impact on tree survival. At two sites we selected 10 tree pairs, i.e., one healthy looking tree and one tree with visual signs of dieback such as dry tops, needle shortening and needle yellowing (n = 40 trees). Vulnerability to cavitation (P50) of the main trunk was assessed in a selected sample set (n = 19) and we thereafter applied SilviScan technology to measure cell dimensions (lumen (b) and cell wall thickness (t)) in these specimen and in all 40 trees in tree rings formed between 1990 and 2010. In a first analysis step, we searched for anatomical proxies for P50. The set of potential proxies included hydraulic lumen diameters and wall reinforcement parameters based on mean, radial, and tangential tracheid diameters. The conduit wall reinforcement based on tangential hydraulic lumen diameters ((t/bht)2) was the best estimate for P50. It was thus possible to relate climatic extremes to the potential vulnerability of single annual rings. Trees with top dieback had significantly lower (t/bht)2 and wider tangential (hydraulic) lumen diameters some years before a period of water deficit (2005–2006). Radial (hydraulic) lumen diameters showed however no significant differences between both tree groups. (t/bht)2 was influenced by annual climate variability; strongest correlations were found with precipitation in September of the previous growing season: high precipitation in previous September resulted in more vulnerable annual rings in the next season. The results are discussed with respect to an “opportunistic behavior” and genetic predisposition to drought sensitivity.
Authors
Belachew Gizachew Zeleke Svein Solberg Erik Næsset Terje Gobakken Ole Martin Bollandsås Johannes Breidenbach Eliakimu Zahabu Ernest William MauyaAbstract
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Authors
Lise Dalsgaard Holger Lange Line Tau Strand Ingeborg Callesen Signe Kynding Borgen Jari Liski Rasmus AstrupAbstract
Soil organic carbon (C), accumulated over millennia, comprise more than half of the C stored in boreal and temperate forest landscapes. We used the Norwegian national forest inventory and soil survey network (n = 719, no deep organic soils) to explore the validity of a deterministic model representation of this pool (Yasso07). We statistically compared simulated and measured soil C stocks and related differences (measured – simulated) to site factors (drainage, topography, climate, vegetation, C-to-N ratio, and soil classification). Median C stocks were 5.0 kg C·m−2 (model) and 14.5 kg C·m−2 (measurements). Soil C differences related to site factors (r2 of 0.16 to 0.37). For Brunisols, Gleysols, and wet Organic soils, differences related primarily to topographic wetness. For Regosols, Podzols, and Dystric Eluviated Brunisols, they related to climate, profile depth, and, in some cases, drainage class and site index. We argue that soil moisture regimes in our study area overrule tree productivity effects in the determination of soil C stocks and present conditions for soil formation that the model cannot (and does not explicitly) account for. These are processes such as humification and podsolization that involve eluviation and illuviation of dissolved organic C (DOC) with sesquioxides to form spodic B horizons and carbon enrichment due to hampered decomposition in frequently anoxic conditions.
Abstract
A controlled climatic chamber microcosm experiment was conducted to examine how light affects the hourly sporulation pattern of the beneficial mite pathogenic fungus Neozygites floridana during a 24 h cyclus over a period of eight consecutive days. This was done by inoculating two-spotted spider mites (Tetranychus urticae) with N. floridana and placing them on strawberry plants for death and sporulation. Spore (primary conidia) discharge was observed by using a spore trap. Two light regimes were tested: Plant growth light of 150 μmol m−2 s−1 for 12 h supplied by high pressure sodium lamps (HPS), followed by either; (i) 4 h of 50 μmol m−2 s−1 light with similar HPS lamps followed by 8 h darkness (full HPS light + reduced HPS light + darkness) or (ii) 4 h of 50 μmol m−2 s−1 red light followed by 8 h darkness (full HPS light + red light + darkness). A clear difference in hourly primary conidia discharge pattern between the two different light treatments was seen and a significant interaction effect between light treatment and hour in day during the 24 h cycle was observed. The primary conidia discharge peak for treatment (ii) that included red light was mainly reached within the red light hours (19:00–23:00) and the dark hours (23:00–07:00). The primary conidia discharge peak for treatment (i) with HPS light only was mainly reached within the dark hours (23:00–07:00).
Authors
Ingerd Skow Hofgaard Till Seehusen Heidi Udnes Aamot Hugh Riley Jafar Razzaghian Vinh Hong Le Anne-Grete Roer Hjelkrem Ruth Dill-Macky Guro BrodalAbstract
No abstract has been registered