Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2006
Sammendrag
We have made and partially sequenced two subtracted cDNA libraries, one representing genes predominantly expressed in a tree from an early-flushing family of Norway spruce (early-flushing library; EFL) and the second from a late flushing family (late flushing library; LFL), during 4 weeks before bud burst. In the EFL, expressed sequence tags (ESTs) encoding proteins of the photosynthetic apparatus and energy metabolism and proteins related to stress (abiotic and biotic) and senescence were abundant. ESTs encoding metallothionein-like and histone proteins as well as transcription factors were abundant in the LFL. We used quantitative real-time reverse transcription polymerase chain reaction to study the expression patterns of 25 chosen genes and observed that the highest levels of activity for most genes were present when plants were still ecodormant. The results indicate that the late flushing is not a result of a delay in gene activity, but is rather associated with an active transcriptional process. Accordingly, certain metabolic processes may be turned on in order to prevent premature flushing. We discuss the putative role of the studied genes in regulation of bud burst timing. Among the candidate genes found, the most interesting ones were the DNA-binding proteins, water-stress- related genes and metallothioneins. Expression patterns of some genes involved in chemical modification of DNA and histones indicate that epigenetic factors are involved in the timing of bud burst. In the obtained transcriptomes, we could not find genes commonly believed to be involved in dormancy and bud set regulation (PHY, CRY, ABI etc.) in angiosperm plants.
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Fine root production, respiration, longevity and mortality are the major processes in carbon dynamics of the forest soils. The objective of the present work was to determine fine root biomass, respiration and root longevity. The study was carried out at a ten year-old stand of planted Norway spruce (Picea abies) (a clearcut, dominated by natural regrowth of Scots pine and birch) and three stands of Norway spruce, approximately 30, 60 and 120 years old, during 2001 and 2002. The stands were located at Nordmoen, a plain of sandy deposits in southeast Norway.Root biomass of both trees and understorey vegetation (0-1, 1-2 and 2-5 mm in diameter) in the humus layer and mineral soil horizons (to depth of 60 cm) was sampled by soil coring. Root respiration was performed in situ, by measuring the CO2 of excavated fine roots by using the CIRAS-I portable gas analyser. For the root turnover study, altogether 60 minirhizotrones were installed and images were processed. Root biomass and necromass (g m-2), specific root length (SRL, m g -1), root length density (RLD, cm cm-3), number of root-tips and mean longevity (y) were estimated.Root biomass was 2-3 times higher in the mineral soil than in the humus horizon. Compared with other stands, root biomass, SRL, RLD and the number of root tips were highest in the 30-year-old stand. At the 10 and 120 year-old stands understorey vegetation roots counted for 70 and 40% of total root biomass, respectively. The amount of necromass at 60 year-old stand was about twice as high (45%) compared to other stands.Root respiration (g C/min./g roots) was significantly lowest at 10-year-old stand. Root respiration among 30, 60 and 120 year-old stands was not significantly different, but it was highest in the 60-year-old stand. The respiration varied seasonally, with high peaks during the summer and lower values during the spring and autumn. Fine root longevity of tree and understorey roots at the 10-year-old stand were 1.2 and 1.4 years, respectively.It is concluded that stand age may influence the dynamics of the fine roots. The complexity of influences will be discussed.
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The role of light in control of cyathia abscission and bract discolouration in poinsettia (Euphorbia pulcherrima) is unclear. The aim of this work was to study the involvement of photosynthetic photon flux (PPF) and extended photoperiod from 10 to 13, 16 or 24 hours with supplemental lighting at the end of the culture period on development of bract discoloration at marketing stage of the plants, and the postharvest performance of cyathia abscission in interior climate of two poinsettia cultivars, `Lilo" and `Millenium". The plants were grown at different photoperiods with supplemental PPF of 73 and 146 µmol m-2 s-1 at plant level. The extended supplemental light treatments were given for one, two or three weeks at the final cultivation period before marketing stage. Extended photoperiod from 10 up to 24 h had no influence on discolouration of the bracts as black and greenish areas of the bract in `Millenium". In contrast, `Lilo" developed serious bract discoloration at photoperiods longer than 13 h. The most serious symptom appeared at 24 h and three weeks of exposure time. Extended photoperiods with supplemental lighting enhanced cyathia abscission at the end of the culture time and during the postharvest test in interior climate. `Millenium" had a better ability to retain cyathia than `Lilo". It is concluded that poinsettia plants should be grown in a photoperiod not longer than 13 h in order to maintain a low rate of cyathia abscission at the end of the production period and during the first 2-3 weeks in interior climate.
Forfattere
Sonja Klemsdal Karen Rae Bone May Bente Brurberg Erling Fløistad Roar Moe Dag-Ragnar BlystadSammendrag
The relative distribution of PoiBI in different tissues and in different parts ofthe plants was quantified using the comparative Ct method and a new developed TaqMan real-time PCR assay. Five samples were analysed from each of six different nodes equally distributed along the height of the plant. Also samples from the top of the plant, from the stem base and the primary and secondary roots were studied. The quantitative real-time PCR test proved to be a very sensitive test. Highest level of phytoplasma was found in the bark samples while the stem core samples contained little or no detectable phytoplasma. The lack of accumulation of phytoplasma in sink tissues indicates restricted phloem translocation of PoiBI. There were large plant-to-plant variations in PoiBI content and further studies including more plants will be needed in order to reveal the general distribution of PoiBI and its possible correlation to branching in poinsettia.
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VIPS (Varsling Innen PlanteSkadegjørere) has been developed under a government-funded action for reducing risk connected to the use of pesticides. Inputs to the forecasting models are weather data from the Bioforsk Agrometeorological Service consisting of a network of 80 weather stations, weather forecasts from the Norwegian Meteorological Institute and biological observations from the Norwegian Agricultural Extension Service. The service is open for the public, free of charge at www.vips-landbruk.no. At the moment VIPS includes forecasts for Stagonospora nodorum (glume blotch), Drechslera teres (net/spot blotch), Rhynchosporium secalis (scald), Sclerotinia sclerotiorum in oil seed rape, Phytophthora infestans (potato late blight), Mamestra brassicae (cabbage moth), Delia radicum (cabbage root fly), Psila rosae (carrot root fly), Venturia inequalis (apple scab), Cydia pomonella (apple moth) and Botrytis cinerea in strawberry. Models for additional pests/diseases are under development. During the growing season the occurrence of several pests and diseases are recorded through a message system. VIPS also includes a programme to assess the need for control of weeds in cereal fields (choice of herbicide(s) and calculation of doses). Current development aim at transferring the service from weatherstation-based to farm-based pest forecasts. Use of radar measurements of precipitation in combination with online interpolation of the other weather factors from nearest weather stations is expected to improve precision in the pest forecasts as well as farmers "ownership" to the information presented.