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.
2007
Sammendrag
Ved frøavl av engrapp må tunrapp bekjempes både i gjenleggsåret og første engår. I gjenleggsåret kan dette oppnås ved falskt såbed eller sprøyting med liten dose Hussar OD (5 g/daa) når engrappen er på 2-3 bladstadet, men kombinasjon av de to tiltaka kan i mange tilfeller skade kulturgraset. Dersom en har vært heldig med det falske såbedet, er det ingen grunn til å sprøyte med Hussar før tunrapp eller annet grasugras spirer på nytt om ettersommeren eller høsten. Behovet for Hussar-sprøyting om våren i engåret (10 g Hussar OD pr daa) må vurderes ut fra forekomsten av små, overvintrende tunrapplanter, men som regel vil denne sprøytinga være nødvendig av hensyn til renheten på frøvaren. Avpussing av godt etablerte engrappgjenlegg (mer enn 20 cm høye) i siste halvdel av september gir flere frøstengler og dermed større frøavling, men øker samtidig behovet for Hussar-sprøyting om våren i engåret.
Sammendrag
Legde kan gi groing, kvalitetsforringelse og stor prisreduksjon i høsthvete. Vekstregulering er kun aktuelt som hjelpemiddel for å hindre legde. En kan få negative effekter av vekstregulatorer dersom vekstforholdene den nærmeste tida etter behandling er stressende for plantene. Ved sterk forkorting får en oftere negative effekter, dersom ikke en manglende behandling ville ført til sterk legde. I tillegg er det forskjeller på hvor skånsomme de ulike vekstregulatorene er. En bør derfor ikke bruke vekstregulatorene dersom det er fare for stress rett etter behandling. Behovet for regulering vil også være mindre under slike forhold. CCC viser seg ofte å være den mest skånsomme vekstregulatoren. Midlet er skånsomt i seg selv, i tillegg skjer behandlingen på et tidspunkt der en sjelden har sterk tørke og varme. Dersom høsthveteåkeren er svært kraftig om våren, vil en CCC-behandling være en god forsikring. Ved behov kan en utføre en ytterligere behandling seinere i sesongen. Dersom det ikke er muligheter for behandling med CCC til riktig tidspunkt, eller en velger å se an situasjonen, kan en behandling med Cerone eller Moddus seinere være et godt alternativ. Moddus skal brukes litt tidligere enn Cerone. Cerone er noe mer skånsom enn Moddus, men vil ikke gi så sterk forkorting. Moddus gir ved store doser den sterkeste forkortingen, men også størst risiko for negativ effekt. Mengden bør derfor reguleres etter behov. Det vil sjelden være bruk for full dose i hvete, i de fleste tilfelle vil 20 ml være nok.
Sammendrag
In the north-western European countries Norway, Sweden, United Kingdom (UK) and Ireland, variability in the forms, amounts and timing of phosphorus (P) loss from agricultural land is related to national differences in climate, soil, hydrological conditions and agricultural production. The dissolved form of P constitutes 9"93% of the total phosphorus (TP) in water, subsurface drainage can contribute 12"60% and surface erosion 40"88% of TP transfer. TP export in small agricultural streams is generally in the range 0.3"6 kg ha)1 year)1, with the highest losses in Norway and UK. All four countries are complying with the EU Water Framework Directive and developing a range of measures based on P source with transport controls over P losses. A decreasing trend in TP losses has been detected in agricultural streams following the introduction of measures to reduce erosion in Norway. Average P concentrations in Swedish streams have shown a reduction of nearly 2% per year since 1993 as a result of measures introduced in southern Sweden. However, in two large rivers in agricultural regions of Sweden, the concentrations of suspended solids (SS) and TP were shown to increase by 0.4% and 0.7% per year, respectively, over the period 1975"2004, possibly as a result of climate change. It is too early to detect trends in agricultural contributions to P in surface waters as a result of catchment-sensitive farming (CSF) in the UK and Ireland.
Forfattere
jihong liu clarkeSammendrag
Poinsettia (Euphorbia pulcherrima Willd. Ex Klotzsch), is a contemporary symbol of Christmas in most parts of the world. Today, Europe and North America represent the largest volume of production and sales, but demand is growing quickly in the Australian regions as poinsettia become popular each year (Williams 2005). In Norway, poinsettia is one of the most important pot plants with a yearly production close to 6 million plants. Its ornamental value and innovation potential has laid the foundation for an extensive research in Norway and elsewhere. Two viruses i.e. poinsettia mosaic virus (PnMV) and poinsettia cryptic virus (PnCV) can cause diseases on modern poinsettia cultivars. PnMV gives visible symptoms in poinsettia during parts of the growing season. Growers show great interest to the potential benefits of growing PnMV-free poinsettias. Traditionally, PnMV-free poinsettia plants were obtained by in vitro culture of apical meristems. However, it is a time-consuming method and the regenerated new PnMV-free poinsettia has sometimes lost the branching characteristics which is important for poinsettia. Therefore, we have developed Agrobacterium-mediated transformation approach for poinsettia. Using this method, we have produced transgenic poinsettia with improved resistance against poinsettia mosic virus (PMV). Molecular analyses have confirmed the stable integration of transgenes into the poinsettia genome. The mechanical inoculation experiments of PnMV and Elisa assays revealed the improved PnMV resistance among the transgenic lines. SiRNA analysis has revealed the gene silencing mediated resistance. This is the first report describing Agrobacterium-mediated transformation on poinsettia. The methodology developed could also facilitate the further improvement of this ornamental plant with aims to enhance its disease resistances, quality traits, desirable colour and ornamental values for meeting the markets demands.
Sammendrag
Seed borne diseases can cause serious problems in organic cereal production because no fungicide treatments can be used and so far only few alternative treatments are approved. The effects of alternative seed treatments against net blotch (Drechslera teres) in barley and leaf blotch (D. avenae) in oats were investigated by laboratory tests and field trials at two locations in Norway in 2005. A barley seed lot with 65 % D. teres infected seeds and an oat seed lot with 15 % D. avenae infected seeds were used. The treatments included Inulex*, Terra Biosa**, acetic acid and Cedomon***, in addition to chemical seed treatment (triticonazol + imazalilsulfat) and untreated seeds as controls. Seeds were analysed for germination and pathogens in laboratory (2x100 seeds) and planted in rows of 100 seeds with 8 replicates in each field location. Percentage emergence and seedlings with primary infections were recorded at BBCH 12-13. Infection level of D. teres recorded in laboratory analyses were reduced significantly by Inulex and acetic acid. In field, the best effect was seen by the acetic acid treatment. The effects against D. avenae were generally poor in laboratory tests and the infection level of the oat seed lot used was too low to give primary symptoms in the field. Similar experiments will be carried out in 2006 and results from this will also be presented. *Extract of Inula viscosa. ** Containing lactic acid bacteria and different herbs. *** Commercial seed treatment (BIOAGRI), based on the soil bacteria Pseudomonas chlororaphis.
Forfattere
Erik Joner Colette Munier-Lamy Barbara GougetSammendrag
An old mine spoil at a 19th century mining site with considerable residues of uranium (400-800 mg U kg-1) was investigated with respect to U concentrations in soil and plants, and tolerance to U in the soil microbial community, in order to describe the bioavailability of U. Measurements of soil fractions representing water soluble U, easily exchangeable U and U bound to humified organic matter showed that all fractions contained elevated concentrations of U. Plant U concentrations were only ten times higher at the mine spoil site compared to the reference site (3 mg U kg-1 vs. 0.3 mg U kg-1), while the most easily available soil fractions contained 0.18-0.86 mg U kg-1 soil at the mine spoil. An ecotoxicity bioassay using incorporation of [3H]thymidine into the indigenous microbial communities of the two soils in the presence of increasing U concentrations showed that micro-organisms at the mining site were sensitive to U, but also that they had acquired a substantial tolerance towards U (EC50 of UO2-citrate was approx. 120 µM as compared to 30 µM in the reference soil). In the assay, more than 40% of the microbial activity was maintained in the presence of 1mM UO2-citrate, vs. 3% in the reference soil. We conclude that U-enriched mining waste can contain sufficiently elevated concentrations of bioavailable U to affect indigenous micro-organisms, and that bioavailable U imposes a selection pressure that favours the development of a highly uranium tolerant microbial community, while plant uptake of U remains low.
Sammendrag
Numerous fungicide applications are often needed to control powdery mildews in greenhouse-grown crops, and consequently there is an increasing demand for alternative means to control them. In commercial greenhouses, attack of powdery mildew caused by Podosphaera xanthii in cucumbers and P. pannosa in cut roses was controlled by weekly sprays of C-Pro CE601, a dilution of grapefruit seed extract (GSE). The raw material of GSE, delivered by Citricidalâ, is a glycerolic extract from seed and juiceless pulp of grapefruits (Citrus paradise). In both cultures C-Pro at 2000 ppm achieved as good control as treatments with penconazole or triforine. The mean level of attack by powdery mildew on leaves of cut roses one week after the last of three weekly treatments, was 9.8, 12.9 and 40.5 % for penconazole, C-Pro (2000 ppm), and untreated, respectively. In cucumbers, there was less difference between the untreated control and the different treatments, but for all times of assessments, C-Pro and triforine were better than untreated (P = 0.001). There was no significant difference in cucumber between C-Pro and triforine. Phytotoxicity symptoms like leaf twisting and rolling in roses (cv. Jade and Cezann) and dark green leaves and indications of growth retardation in cucumbers (cv. Ventura) were observed at the higher concentrations used (3000-4000 ppm). Thin layer chromatography of C-Pro CE601 has previously shown presence of benzethonium chloride, a synthetic antiseptic agent. Further research is necessary to determine if the observed effects of the product tested are due to natural compounds or if it is merely due to a synthetic preservative agent added. Our results revealed that C-Pro might be a supplement or even a replacement to some of the current fungicides used against powdery mildew.
Forfattere
Ricardo Holgado Christer MagnussonSammendrag
Cereal cyst nematodes, Heterodera spp., are known world wide as parasites of cereals and grasses. Surveys in Norway have revealed that nematodes belonging to the H. avenae complex occur throughout the country. The cereal cyst nematode species so far recorded in Norway are H. avenae, H. filipjevi, H. pratensis, H. bifenestra and H. hordecalis. Within H. avenae the pathotypes, Ha 11 and Ha 12, "Ha- Knislinge", "Ha- Ringsåsen" and "Ha- Våxtorp" have been encountered. H. filipjevi is represented by the pathotype "West" HfW (Holgado et al., 2007). In cereals, peaks in cyst nematode populations and damage occur every 20-30 years, and seem to occur simultaneously throughout the Scandinavian Peninsula. We do not have reliable information on the mechanisms behind these wide spread fluctuations. Crop rotation and the use of cultivars with resistance are important measures for controlling cereal cyst nematodes, but require detailed information on the occurrence and density of species and pathotypes in the fields (Holgado & Andersson 2005, Holgado et al. 2005, 2006ab). In field soils Ha 11,/12, "Ha-Våxtorp" is often found together with HfW. Resistant cultivars are normally resistant to only one of two species or pathotypes in mixed field populations. Consequently the use of resistant cultivars will lead to an increase of the nematode species or pathotype capable of reproduction, which results in peaks of damage distributed in time. Failure in recognizing the time span of this dynamic may leave the farmer without access to appropriate cultivars when damage occurs. Different species and pathotypes of cyst nematodes may occur simultaneously on the same plant root (Holgado & Magnusson, 2007). This would be an unlikely event without mechanisms reducing competition. Differences in temporal, spatial and physiological niche dimensions between species would support diversity. A better knowledge of key-differences in niche parameters of cereal cyst nematode species would allow for an active management of specific populations, and stabilize their population densities at levels below the threshold of economic damage. Management of niches is management of diversity, and this would allow for an optimal selection of cultivars. In this way the unexpected peaks in cereal damage can be avoided to the benefit of a more stable and sustainable production. The dynamics and principles of coexistence of species in mixed populations need a stronger emphasis in management systems for cereal cyst nematodes.
Forfattere
jihong liu clarkeSammendrag
The complete sequences of the chloroplast genomes of H. vulgare, Sorghum bicolor and A. stolonifera are presented. The sizes of the H. vulgare, Sorghum bicolor and A. stolonifera chloroplast genomes are 136,462, 140,754 and 136,584 bp, respectively. The genomes include a pair of IRs of 21,579 bp (H. vulgare), 22,782 bp (Sorghum bicolor) and 21,649 bp (A. stolonifera) separated by a small single copy region of 12,704 bp (H. vulgare), 12,502 bp (Sorghum bicolor) and 12,740 bp (A. stolonifera) and a large single copy region of 80,600 bp (H. vulgare), 82,688 bp (Sorghum bicolor) and 80,546 bp (A. stolonifera). Comparisons of complete chloroplast genome sequences of Hordeum vulgare, Sorghum bicolor and Agrostis stolonifera with six published grass chloroplast genomes reveal that gene content and order are similar but two microstructural changes have occurred. First, the expansion of the IR at the SSC/IRa boundary that duplicates a portion of the 5" end of ndhH is restricted to the three genera of the subfamily Pooideae (Agrostis, Hordeum and Triticum). Second, a 6 bp deletion in ndhK is shared by Agrostis, Hordeum, Oryza and Triticum, and this event supports the sister relationship between the subfamilies Erhartoideae and Pooideae. Repeat analysis identified 19- 37 direct and inverted repeats 30 bp or longer with a sequence identity of at least 90%. Seventeen of the 26 shared repeats are found in all the grass chloroplast genomes examined and are located in the same genes or intergenic spacer (IGS) regions. Examination of simple sequence repeats (SSRs) identified 16"21 potential polymorphic SSRs. Five IGS regions have 100% sequence identity among Zea mays, Saccharum officinarum and Sorghum bicolor, whereas no spacer regions were identical among Oryza sativa, Triticum aestivum, H. vulgare and A. stolonifera despite their close phylogenetic relationship. The genome information will facilitate the development of CP technology for those crops to improve their agronomic traits.
Forfattere
Christopher Saski Seung-Bum Lee Siri Fjellheim Chittibabu Guda Robert K Jansen Hong Luo Jeffrey Tomkins Odd Arne Rognli Henry Daniell jihong liu clarkeSammendrag
Comparisons of complete chloroplast genome sequences of Hordeum vulgare, Sorghum bicolor and Agrostis stolonifera to six published grass chloroplast genomes reveal that gene content and order are similar but two microstructural changes have occurred. First, the expansion of the IR at the SSC/IRa boundary that duplicates a portion of the 5 end of ndhH is restricted to the three genera of the subfamily Pooideae (Agrostis, Hordeum and Triticum). Second, a 6 bp deletion in ndhK is shared by Agrostis, Hordeum, Oryza and Triticum, and this event supports the sister relationship between the subfamilies Erhartoideae and Pooideae. Repeat analysis identiWed 19- 37 direct and inverted repeats 30 bp or longer with a sequence identity of at least 90%. Seventeen of the 26 shared repeats are found in all the grass chloroplast genomes examined and are located in the same genes or intergenic spacer (IGS) regions. Examination of simple sequence repeats (SSRs) identiWed 16"21 potential polymorphic SSRs. Five IGS regions have 100% sequence identity among Zea mays, Saccharum oYcinarum and Sorghum bicolor, whereas no spacer regions were identical among Oryza sativa, Triticum aestivum, H. vulgare and A. stolonifera despite their close phylogenetic relationship. Alignment of EST sequences and DNA coding sequences identified six C"U conversions in both Sorghum bicolor and H. vulgare but only one in A. stolonifera. Phylogenetic trees based on DNA sequences of 61 protein-coding genes of 38 taxa using both maximum parsimony and likelihood methods provide moderate support for a sister relationship between the subfamilies Erhartoideae and Pooideae.