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.
2009
Abstract
Environmental control of flowering and runnering in three contrasting Fragaria chiloensis populations with geographic origins in Alaska, Oregon, and Chile have been studied under controlled environment conditions. All populations were principal short-day (SD) plants at intermediate temperatures (15 degrees C or 21 degrees C), while at low temperature (9 degrees C) the 'Alaska' and 'Chile' populations were essentially day neutral. However, the populations had contrasting temperature responses for flowering in SD at both constant and fluctuating day/night temperatures. At a day temperature of 18 degrees C, flowering increased with increasing night temperature from 9 degrees C to 21 degrees C in the 'Alaska' population, while the opposite trend was observed in the 'Chile' population. The sparsely flowering 'Oregon' population flowered only in SD within a narrow range of temperatures (15-18 degrees C). Photoperiod (10, 16, or 20 h) had no effect on flower development at 18 degrees C. All populations were runnering freely, but with different temperature and photoperiod modifications. It is concluded that the SD X temperature interaction in the flowering behaviour of the June-bearing cultivated strawberry, F. X ananassa, is inherited to a large extent from F. chiloensis, whereas the species does not appear to have contributed to the long-day (LD) flowering control in everbearing cultivars.
Authors
Øystein Johnsen Igor A. Yakovlev Carl Gunnar FossdalAbstract
Temperature during zygotic and somatic embryogenesis regulates an epigenetic memory in Picea abies. Conditions colder than normal advance the timing of bud burst and bud set, whilst temperatures above normal delay the onset of these processes. The long-lasting memory affects growth and hardiness in the field. We made a search of candidate genes and micro RNAs that could regulate the memory, using specialized library sequencing approaches. Two subtracted cDNA libraries, representing genes that are mainly expressed in plants from a cold (CE) or a warm (WE) embryogenesis, revealed considerable differences in the transcriptomes. Many contigs were unknown. We used qRT-PCR to demonstrate that five genes with no matching in the database were differentially expressed in close correlation with the memory-induced differences in bud set. Partial sequencing of two concatemerized small RNA libraries revealed 199 different small RNAs, with predominant length of 21-nt. We found 24 novel candidate miRNAs among them, and 4 described earlier. Most of the predicted miRNA targets were related to unknown and “no-hit” genes, 5 target different disease-related genes, and 4 contigs were homologous to described functional genes. Using qRT-PCR we confirmed that three selected genes regulated by miRNAs pab-miR100, 175 and 176, could to be involved in the memory regulation. Additionally, several novel miRNAs; pab-miR080, 105, 119, 122, 132, 144a,b and 157 were differentially expressed between epigenetically distinct plants. Our data illustrates that micro RNAs will guide us to candidate genes that are putative elements in the epigenetic machinery, regulating the long-lasting memory that affects adaptive traits in this species.
Authors
Knut Anders Hovstad Silje Borvik Mikael OhlsonAbstract
In modern agricultural landscapes, large herbivores are often restricted in their mobility or are found at low densities, and other animal vectors may therefore be important for seed dispersal. In our study, a range of plant species were able to disperse by attaching seeds to, and having their seeds retained in, the fox fur some distance. We suggest that the red fox may be an important vector for epizoochorous seed dispersal in the agricultural landscape.
Abstract
The report presents model simulations of irrigation water requirements over the period 1973-2008 for various crops in four regions of Norway. A detailed summary in English is given on pp. 47-49.
Authors
Belachew Asalf Tadesse Håvard Eikemo Andrew Dobson Anne-Marte Tronsmo Cecilie Hagen David M. Gadoury Robert C Seem Arne StensvandAbstract
Several non-chemical control agents are now registered and available for control of powdery mildews. However, there is little or no information about their efficacy against strawberry powdery mildew, caused by Podosphera aphanis. Trials were conducted to compare the performance of non-chemical control agents to chemical fungicides under laboratory, greenhouse and high plastic tunnel conditions. The treatments included: AQ10 (active ingredient is Ampelomyces quisqualis, a hyperparasite on powdery mildew), AQ10 + Silwet Gold (organosilicon adjuvant, enhances distribution and wetting), Vacciplant (active ingredient is laminarin, an extract from brown algae), JMS Stylet oil (mineral oil), Rape seed oil + detergent, Thiovit (wettable sulphur), Topas 100 EC (penconazole) + Candit (kresoximmethyl) and water as control. In the greenhouse, one quarter of the recommended dose was used either daily in one experiment or three times per week in another. In the field, half of recommended rates were applied twice weekly. Both in the greenhouse and tunnel experiments, the chemical control Topas + Candit and AQ10 + Silwet Gold significantly reduced disease severity. AQ10,Vacciplant and Thiovit were moderately effective when applied daily in the greenhouse trial, but not significantly different from the water control when applied three time per week in the greenhouse and twice a week in the tunnel experiment. In the plastic tunnel, the JMS stylet oil and Rape seed oil + detergent treatments caused severe phytotoxic reaction (necrosis). AQ10 used alone had the poorest performance in the tunnel. This indicated that the spreader either enhances the effect of AQ10 and/or the spreader itself had an effect. In laboratory experiments with powdery mildew grown on strawberry leaflets in Petri dishes, spore germination after treatments with water, Stylet oil, Candit and Thiovit were 74, 53, 8 and 7%, respectively. The effect of Thiovit found in the laboratory was not reflected in the greenhouse and plastic tunnel trials. We will further explore the protectant, curative and eradicative effects of the compounds included here.
Authors
Trygve S. Aamlid Oiva Niemelainen Maire Rannikko Olav Noteng Michael Waldner Terje Haugen Sanni Junnila Trond Olav Pettersen Tatsiana EspevigAbstract
This report presents second year results and recommendations based on a two year project evaluating the plant growth regulator Primo MAXX® (trineexapac-ethyl) on Nordic golf courses.
Abstract
Due to the exponential increase in production and marketing of engineered nanomaterials, concerns are raised about their inevitable spreading in the environment. Soils, with their high proportion of solid phase, are likely to constitute the major ultimate sink for engineered nanoparticles (ENPs). Regrettably, data are scarce on the potential environmental risks of ENPs on soil ecosystems. The main reason for this key knowledge gap was the lack of methodologies able to trace the ENPs in complex environmental matrices like soils, which already contain a high background of natural nanoparticles (e.g. clays, organic matter, iron oxides). Using neutron activation as a tracer technique enabled us to overcome this hurdle: neutron activated ENPs can readily be quantified by gamma spectrometry, in all kind of samples, including living organisms. Here we examined the uptake and excretion kinetics of cobalt (Co-NPs, APS 3.9 ± 0.8 nm) and silver nanoparticles (Ag-NPs, APS 20.2 ± 2.5 nm) in the earthworm Eisenia fetida, as well as their internal distribution within worms. We compared the uptake, retention time and internal ditribution of Co-NPs and Ag-NPs with those of soluble salts of cobalt and silver. Earthworms were fed over a 28d period with horse manure contaminated with either neutron activated Co-NPs and Ag-NPs, or Co and Ag salts spiked with the radiotracers 60Co and 110mAg. Accumulation and excretion kinetics were assessed by gamma spectrometry on living earthworms along a three month period for silver treatments and a five month period for cobalt treatments. The patterns of accumulation were highly different for cobalt and silver. The concentration ratios [(Bq/g worm) / (Bq/g food)] after 28d uptake were 0.93 ± 0.36 and 2.02 ± 0.65 for Co-NP and Co2+, respectively, while corresponding values for Ag-NPs and Ag+ were 0.015 ± 0.016 and 0.054 ± 0.024, respectively. Almost all absorbed Co-NPs and Co2+ remained within the worms four months after transfer to clean soil, while Ag concentration ratios fell to almost zero within a few days. We investigated futher the distribution of Co-NPs and Co2+ in worms bodies by coupling autoradiography images of worm transects and gamma spectrometry on individual organs. The body wall, mainly composed of muscular fibers, and the reproductive organs (e.g. spermathecae and seminal vesicles) accumulated lower amounts of cobalt than the digestive tract. By far, the highest accumulation was found in the blood, namely in the pseudo-hearts.
Abstract
No abstract has been registered
Authors
Frode Eick K Maleta Espen Govasmark Asim K. Duttaroy Gunnar Aksel BjuneAbstract
No abstract has been registered
Abstract
No abstract has been registered