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.
2010
Abstract
No abstract has been registered
Abstract
In Nordic countries organic farming started as bio-dynamic farms in the 1930s, and still in the 1970s only a small number of farms were organic. Since then the acreage of organic farming has increased and in 2007 Sweden had 222 268 ha (7.9%), Finland 147 557 ha (6.4 %), Denmark 147 482 ha (5.4%), Norway 43 033 ha (4.7%) and Iceland 4 684 ha (0.27%). In northern areas the short vegetation period combined with low temperatures reducing mineralisation causing nutritional deficit may restrict yields. As mineral fertilizers are prohibited in organic farming, plant nutrition and yield depend on proper microbial activity for nutrient cycling. Plant parasitic nematodes (PPN) reduce plant growth, while microbivorous nematodes (MBN) increase nutrient accessibility. Nitrogen fixating legumes, used to improve soil nitrogen levels, may increase densities of PPN to levels causing crop damage. Management of PPN in organic farming relies on knowledge of population dynamics, damaging thresholds and cultural methods like weed control, sanitation, mulching, crop rotation and resistant cultivars. Keeping PPN below damaging levels and supporting beneficial MBN to improve mineralisation would increase yields and improve quality of organics crops in northern areas. Management of MBN is less well understood, but may be of crucial importance for organic farming in northern areas.
Abstract
We have recently found that Norway spruce (Picea abies (L.) Karst.) can rapidly adjust its adaptive performance, probably through an epigenetic mechanism. This appears to employ a kind of long-term memory of temperature sum and (probably) photoperiod from the time of its embryo development. In our research we made identical controlled crosses and produced seed lots under controlled temperature and day-length conditions and later observed phenology, growth and hardiness traits in the progenies. It was repeatedly found that temperature conditions during seed set, in particular, influence the phenotypes of the offspring; seedlings from seeds produced under warm conditions have later terminal bud set and reduced autumn frost hardiness than those from seed produced under colder conditions, and thus perform like a more southern provenance. When embryonic clones were derived from mature zygotic embryos and were cultured at different temperatures, the plants cultured under warm in vitro temperature were the last to set bud and grew taller than those cultured at lower temperatures. Progenies produced in Norway by Central European mother trees had a bud set curve skewed towards that of the local Norwegian performance. A comparison of the performance of seedlings from seeds collected in the same provenance regions in 1970 and 2006 shows that the more recent seed lots consistently produce taller seedlings with a later bud set, probably due to higher temperatures during seed production in 2006. The effect of reproductive environment has been shown to persist for years. It mimics the variation between provenances from different latitudes and altitudes and may explain much of the observed variability in bud set and early height growth between natural populations of Norway spruce. The observed phenomenon suggests an epigenetic mechanism in the developing embryo, either zygotic or somatic, that senses environmental signals such as temperature and influences adaptive traits. Research is underway to understand the molecular basis of this mechanism. We will discuss the implications of this epigenetic phenomenon for the interpretation of provenance differences, for tree breeding and for its possible role in adaptation to climate change.
Authors
Jens Rohloff Per Winge Jahn Davik May Bente Brurberg Keithanne Mockaitis Vladimir Shulaev Stephen K, Randall Atle M. Bones Muath AlsheikhAbstract
In order to support functional genomics research in octoploid (Fragaria x ananassa Duch.) and diploid (F. vesca) strawberry, a customized Fragaria microarray chip was developed as a joint collaboration between Graminor Breeding Ltd. and NTNU. F. vesca cDNA sequences were provided by The Center for Genomics and Bioinformatics, Indiana University (an assembly of >3 million reads from GS-FLX Titanium - Roche/454 Life Sciences sequencing), and about 59,000 publicly available Fragaria EST sequences were uploaded from NCBI. In addition, ~190 Mb of preliminary draft genome sequences from F. vesca were provided by the Strawberry Genome Sequencing Consortium (courtesy to V. Shulaev). cDNAs used as templates for probe design were validated by BlastN against the F. vesca draft genome excluding cDNAs of microbial origin. Genes not represented in the cDNA collection were identified by screening F. vesca draft genome against protein sequences from Arabidopsis thaliana, Vitis vinifera, Ricinus communis and Populus trichocarpa. Exon sequences from genes not found in the cDNAs were included. In total, 43723 unique 60-mer probes were designed and the Agilent eARRAY tool was used to produce a 4x44k format microarray chip. Fragaria chip applicability and feasibility for transcriptional profiling was investigated using either abiotic (low temperature) or biotic (pathogenic fungi) stress treatment. Microarray data will be subsequently integrated with other omics data to address gene-regulatory networks and biological functions. Cold acclimation experiments were focused on short- and long-term effects in meristematic tissue, and revealed the up-regulation of ~100 cold-responsive genes (transcription factors, dehydrins, enzymes), and transcripts involved in starch breakdown and raffinose biosynthesis. Beside central metabolism, secondary metabolism was also strongly modulated as seen by changes in the expression of flavonoid biosynthesis-related genes. Time-course studies of transcriptional responses in F. vesca accessions showing contrasting resistance toward the pathogen Phytophthora cactorum are in progress, and will be presented in-depth.
Abstract
Docks are among the most important perennial weeds in grasslands throughout the world and the need for more effective control methods is especially crucial in organic forage production. To find more effective control methods, field trials over 2 years at 4 Norwegian locations, were carried out mainly as a full-factorial design, including factors expected to reduce docks significantly. (i) Date of grassland establishment: may be important for preventing/decreasing the flush of seedlings from seeds as well as shoots from root fragments.(ii) False seedbed preparation: to decrease soil seed bank. (iii) Use of nurse crop (cover crop) to increase competitiveness against Rumex seedlings. (iv) Cutting the taproot, using a rotary tiller before ploughing, or the "dock-plough" (a skimmer modified to cut roots in the entire furrow width at ca 7 cm depth): as new shoots mostly come from the neck and the upper 5 cm of the taproot. (v) Ploughing depth and skimming: to decrease shoots from root fragments. Weed development was assessed as the number of emerging Rumex seedlings and plants sprouting from root fragments. Results indicated that frequently more plants emerged from seeds than from root fragments. Neither renewing the grassland in summer, nor the use of the rotary tiller or the "dock plough" reduced the number of docks in the renewed grasslands. The use of the false seedbed and nurse crop, at some locations and years, reduced the number of docks in the renewed grasslands. Deep ploughing (24cm) reduced the number of Rumex plants from roots by 65% percent compared to shallow ploughing (16cm). Furthermore, the use of a skimmer reduced the number of docks sprouting from roots by 28%. Among the investigated factors, competitiveness, false seedbed and ploughing depth, as well as ploughing quality, seems to be the most promising factors for reducing the number of docks in renewed grassland.
Abstract
No abstract has been registered
Authors
Roman Gebauer Josef Urban Isabella Børja Vladimir Gryc H Vavrcik Daniel Volarik Petra RychteckaAbstract
The drought stress presents a significant threat for the forest ecosystems. The climate change brings some extreme climatic conditions including longer and more common periods of the drought into the still more forest stands. Current forest management and consecutively wood processing industry in the Czech Republic is nowadays dependent mostly on the Norway spruce. In the same hand, Norway spruce is probably the most threatened tree species by the climate change. Therefore there is a demand for the suitable methodology to monitor the direct effect of the drought on the trees. Presented publication puts together different methods of the evaluation of the water stress and tries to assess their value for the study of the water stress. Of course, there are dozen of the methods to study the water stress. In this handbook we skipped the difficult and expensive techniques and focused rather on the simple methods, suitable for the field use. Methodology begins with the description of the meteorological measurements with current widely available instrumental techniques (i.e. measurements of the intensity of global radiation, air temperature and humidity, wind speed and precipitation) and continues with the monitoring of the soil water content and soil water potential. Then there is a focus on the direct effect of the water stress on the plant. We began with the plant root system since we believed that the fine roots were the most susceptible part of the tree. The focus was on their morphology, anatomy and biological activity. In the aboveground part of the tree we focused on the development of the hydraulic architecture of the tree on the microscopic level. This theoretical analysis was validated by the in-situ measurements of the sap flow. Direct and immediate effect of the water stress on the plant water status is described in the means of the plant water potential. Similarly to the hydraulic architecture we dealt with both the xylogenesis (on the cellular level) and the stem increment measured (on the tree level) by the logging band dendrometers. Finally we discussed the effect of the plant water status on the mineral nutrition of the tree. To conclude, none of the methods alone can implicate the complexity of the water stress, however the combination of the different views gives rather good insight on the tree condition and enable to predict the further tree development.
Authors
Karl ThunesAbstract
No abstract has been registered
Abstract
Traditional wood preservatives based on biocides are effective against wood-deteriorating organisms because of their toxicity. By contrast, modified woods are non-toxic by definition. To investigate the efficiency of various wood modifications, quantitative real-time polymerase chain reaction (qPCR) was used to profile the DNA amounts of the white-rot fungus Trametes versicolor (L.) [Lloyd strain CTB 863 A] during an 8-week-long growth period in treated Pinus sylvestris (L.) sapwood. The studied wood was modified by acetylation, furfurylation, and thermal treatment. The traditional wood preservatives bis-(N-cyclohexyldiazeniumdioxy)-copper (Cu-HDO) and chromated copper arsenate (CCA) were used as references, whereas untreated P. sylvestris (L.) sapwood served as a control. The maximum levels of fungal DNA in native wood occurred at the end of the experiment. For all wood treatments, the maximum fungal DNA level was recorded after an incubation period of 2 weeks, followed by a decline until the end of the trial. For the preservative-treated woods, Cu-HDO showed the lowest level of fungal DNA throughout the experiment, indicating that exploratory hyphal growth is limited owing to the phytotoxicity of the treatment. The other treatments did not inhibit the exploratory hyphal growth phase. We conclude that qPCR studies of hyphal growth patterns within wood should provide a powerful tool for evaluating and further optimizing new wood protection systems.
Abstract
The pinewood nematode (PWN) is one of the worst tree-killing exotic pests in East-Asian countries. The first European record of establishment in Portugal in 1999 triggered extensive surveys and contingency plans for eradication in European countries, including immediate removal of large areas of conifer host trees. Using Norway as an example, we applied a simulation model to evaluate the chance of successful eradication of a hypothetical introduction by the current contingency plan in a northern area where wilting symptoms are not expected to occur. Despite a highly variable spread of nematode infestations in space and time, the probability of successful eradication in 20 years was consistently low (mean 0.035, SE 0.02). The low success did not change significantly by varying the biological parameters in sensitivity analyses (SA), probably due to the late detection of infestations by the survey (mean 14.3 years). SA revealed a strong influence of management parameters. However, a high probability of eradication required unrealistic measures: achieving an eradication probability of 0.99 in 20 years required 10,000 survey samples per year and a host tree removal radius of 8,000 m around each detection point.