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.
2008
Forfattere
Mekjell Meland Magne Eivind MoeSammendrag
The apple cultivar `Elstar" is the latest is the latest commercial maturing cultivar in Norway of high fruit quality when properly managed. In May 2006 a four years experiment with four different crop loads (2-4-6-8 flowers/fruitlets per TCSA cm2) were established at two stages (first bloom open and 20 mm fruitlets diameter) and compared to unthinned. Preliminary results from the two first seasons are presented. Fruit growth determination was conducted on individual fruits on each treatment during the season. Thinning at bloom to different crop levels gave a significant lower fruit set than thinning at the fruitlets stages to the same levels the first year. However, the fruit weight and the soluble solid contents were significant larger and ground colour improved when bloom thinning. The final fruit numbers at harvested was less than the amount established at bloom and fruitlets. There were significant differences between the different treatments in final fruits per TCSA and fruit set which reflected the different crop levels. Fruit weight and soluble solid contents were largest with lowest crop load and decreased with increasing crop levels. There was a strong crop load effect from the year before on the amounts of return bloom per tree. The trees thinned at bloom had significant more flower clusters than thinned at the fruitlet stage of 20 mm. The untreated, control trees had the lowest amount of flower clusters. The amount of return bloom declined with increasing crop load on the trees. The second year yield and fruit weight were larger when thinned at bloom. The highest crop load the second year was when thinned at bloom to the levels of 2 and 4 apples per TCSA the year before. The trees with the highest crop load the last year managed to give only a small crop. The fruit quality was in general high for all treatments.
Sammendrag
Effects of temperature on the development and chemical composition of two cloudberries (Rubus chamaemorus L.) cultivars ("Fjellgull", "Nyby") were studied in a phytotron experiment. "Fjellgull" is a female cultivar while "Nyby" is bisexual (hermaphrodite). Pollen from a male cultivar "Apollen" or from "Nyby" was used to pollinate "Fjellgull". Selfpollination in "Nyby" was assisted by striking open flowers gently with a small brush. In addition, part of the flowers of both cultivars were treated with gibberellic acid (GA3, 10 µg dissolved in 10 µl ethanol). Plants were grown in 24-h photoperiod at constant temperatures of 18, 15, 12 and 9°C. Time from pollination to ripening increased in both cultivars with decreasing temperature from about 35 days at 18°C to about 60-65 days at 9°C. Time for fruit development was not significantly affected by GA3. Berries of "Fjellgull" were significantly larger than those of "Nyby". In both cultivars, the largest berries were found at the treatments 12 or 9°C. On the other hand, seed size was smallest at 9°C and the proportion of seed weight of total fresh weight of berry decreased with decreasing temperature. Treatment with GA3 significantly reduced the average seed size in both cultivars. Pollen type had no significant effect on the rate of development or size of berries in "Fjellgull". Ripe berries were frozen at harvest at -100°C, and tannin enriched extracts were analyzed for metabolites using liquid chromatograpy " mass spectrometric (LC-MS) techniques. In addition total phenols and total anthocyanins were analysed as described by Deighton et al. (2000). Statistical analysis and data mining were performed using a principal component analysis approach. Preliminary results indicate differences in the metabolic profiles between berries grown at low temperatures compared to berries grown at high temperatures.
Forfattere
Trygve S. Aamlid Mats Larsbo Nick JarvisSammendrag
Water repellency in golf putting greens may induce preferential `finger flow" leading to enhanced leaching of surface applied fungicides. We examined the effects of root zone composition, treatment with a non-ionic surfactant and use of either the fungicide iprodion (3-(3,5-dichlorophenyl)-N-(1-methylethyl)2,4-dioxo-1-imidazoline-carboximide) or a combination of azoxystrobin (Methyl (E)-2-{2-[6-(2-cyanophenoxy) pyrimidin-4-yloxy]phenyl}-3-methoxyacrylate) and propiconazole (1-[[2(2,4-Dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl]methyl]1-H-1,2,4-triazole) on soil water repellency, soil water content distributions, fungicide leaching and turf quality during one year. Soil water repellency was measured both using the water drop penetration time test and tension infiltrometers. Our study was made on a three year old experimental green seeded with creeping bentgrass (Agrostis stolonifera L.) `Penn A-4" at Landvik in SE Norway. The facility consists of 16 lysimeters with two different root zone materials, i) straight sand (1% gravel, 96% sand, 3% silt and clay, 0.4% (w/w) organic matter) (SS), and ii) straight sand mixed with garden compost to an organic matter content of 2.1% (Green Mix (GM)). Results showed that surfactant treatment reduced soil water repellency and the spatial variation in soil water contents. Fungicide leaching was close to zero for the GM lysimeters probably due to stronger sorption. Concentrations in the drainage water from SS lysimeters often exceeded surface water guideline values for all three fungicides, but surfactant treatment dramatically reduced fungicide leaching from these lysimeters. In autumn and winter, surfactant treated plots were more infected with fungal diseases probably because of higher water content in the turfgrass thatch layer.
Forfattere
Bagher Farmani Nils-Otto Kitterød Henk KeersSammendrag
Flow parameters in the vadose zone of an ice-contact delta near Oslo"s Gardermoen Airport were estimated by inverse flow modeling combining time-lapse ground-penetrating radar (GPR) travel-time (TT) tomography and groundwater (GW) table data. Natural water infiltration from the 2006 snowmelt was used as the upper boundary condition in forward flow simulations. The lower boundary condition was the outflux of water from the vadose zone derived by time derivative of the GW table. The inverse flow modeling was done using different combinations of time-lapse GPR TT tomography and time series of the level of the GW table. The purpose was to assess the improvements in parameter estimations and the information value of the different data sets. Flow parameters estimated by conditioning only on time-lapse GPR TT tomography capture the development of the wet front but fail to simulate the GW table fluctuations. Inverse flow modeling conditioned on only GW table did not simulate the wet front correctly but decreased the objective function better than conditioning on time-lapse GPR data. If the inversion is conditioned on both time-lapse GPR data and the GW table fluctuations, the final estimates of the flow parameters are close to the estimates from the inversion conditioned on only GW table data. This result was obtained because the moving GW table was monitored continuously in time while the GPR data were sampled only three times during the infiltration event; thus, observations of the GW table had higher weights in the objective function than did observations derived from GPR tomograms. Finally, we did forward flow modeling with the estimated parameter sets and compared the flow paths with an independent tracer experiment performed at the field site in 1999. The results showed that anisotropy in the intrinsic permeability was an important parameter that should be considered when simulating the flow paths. However, volumetric soil water content distribution is not strongly related to the anisotropy of intrinsic permeability. Therefore, anisotropy cannot be correctly estimated by inverse flow modeling conditioned on volumetric soil water content only.
Forfattere
Anne-Kristin LøesSammendrag
Prosjektet "Frafallet blant norske økobønder ? hva er årsakene?" (2007-08) har gjennomført en spørreundersøkelse blant alle bønder som meldte seg ut av den økologiske sertifiseringsordningen og dermed ut av Debio mellom 2004 og 2007. Spørreskjemaet ble også sendt til en kontrollgruppe med bønder som drev økologisk i 2006. Alle bøndene i undersøkelsen hadde et driftsomfang som gjorde at de var kvalifisert til å motta produksjonstilskudd. Resultatene ble sammenstilt med opplysninger fra Statens landbruksforvaltning om arealer og dyretall. Et urovekkende resultat er at 25% av dagens økobønder planlegger å melde seg ut av Debio-ordningen i løpet av 5-10 år. Av dem som vil slutte er det 20% som vil legge ned drifta, 40% som vil gå over til konvensjonell drift, og hele 40% som vil drive etter økologiske retningslinjer, men uten Debiogodkjenning. Når det gjelder dem som har meldt seg ut, er det 55% av disse som nå driver konvensjonelt. 10% har startet opp igjen som Debiobønder,16% har lagt ned drifta, og 18% hevder at de driver etter økologiske retningslinjer uten sertifisering. Siden Debio-sertifisering er en forutsetning for å motta tilskudd til økologisk produksjon er det overraskende at så mange bønder er interessert i økologisk landbruk, men ikke godkjenningsordningen. For mye byråkrati med Debiosertifisering og ?kontroll ble da også oppgitt som den klart viktigste årsaken til utmelding av dem som hevder å drive etter retningslinjene, men uten Debio-inspeksjoner. For dårlig lønnsomhet og usikkerhet rundt landbrukspolitikken var også viktige årsaker til utmelding, mens sosiale forhold som manglende støtte fra familie og naboer var av liten betydning. Resultatene blir nå analysert statistisk, og bearbeidet ved hjelp av en teoretisk beslutningsmodell.
Sammendrag
Fusarium head blight (FHB) is a widespread and destructive disease of cereals caused by a number of Fusarium species. Under field conditions a mixture of Fusarium species exists. While FHB in wheat has been well studied, Fusarium infection of oats has not yet been characterized. Little is known about how the presence of a mixture of different Fusarium species in the same sample affects the mycotoxin production. During flowering plants of wheat and oats grown under greenhouse conditions were spray inoculated with single and multiple Fusarium species (F. graminearum, F. culmorum, F. avenaceum, F. poae and F. langsethiae). Chemical toxin analysis of harvested grain showed that the content of mycotoxins in oat were generally lower than in corresponding wheat samples. Neither T-2 nor HT-2 was detected in wheat or oat. Neither was it possible to detect F. langsethiae in the kernels when analysed by real-time TaqMan PCR. All wheat samples inoculated with F. graminearum contained relative high levels of deoxynivalenol. Samples infected with F. culmorum contained nivalenol in addition to deoxynivalenol. Moniliformin was detected at levels below the quantification limit in one third of the samples. The inoculation experiment was repeated with an adjusted inoculation procedure for F. langsethiae and F. poae, resulting in good establishment of all Fusarium species. The amounts of the different Fusarium species and the level of the corresponding mycotoxins were determined. The interactions between the Fusarium species regarding establishment on the fungus on the developing kernels and the production of the mycotoxins, was discussed.
Sammendrag
Fusarium head blight (FHB) is a widespread and destructive disease of cereals caused by a number of Fusarium species. Under field conditions a mixture of Fusarium species exists. While FHB in wheat has been well studied, Fusarium infection of oats has not yet been characterized. Little is known about how the presence of a mixture of different Fusarium species in the same sample affects the mycotoxin production. During flowering plants of wheat and oats grown under greenhouse conditions were spray inoculated with single and multiple Fusarium species (F. graminearum, F. culmorum, F. avenaceum, F. poae and F. langsethiae). Chemical toxin analysis of harvested grain showed that the content of mycotoxins in oat were generally lower than in corresponding wheat samples. Neither T-2 nor HT-2 was detected in wheat or oat. Neither was it possible to detect F. langsethiae in the kernels when analysed by real-time TaqMan PCR. All wheat samples inoculated with F. graminearum contained relative high levels of deoxynivalenol. Samples infected with F. culmorum contained nivalenol in addition to deoxynivalenol. Moniliformin was detected at levels below the quantification limit in one third of the samples. The inoculation experiment was repeated with an adjusted inoculation procedure for F. langsethiae and F. poae, resulting in good establishment of all Fusarium species. The amounts of the different Fusarium species and the level of the corresponding mycotoxins were determined. The interactions between the Fusarium species regarding establishment on the fungus on the developing kernels and the production of the mycotoxins, will be discussed.
Forfattere
Marit Larsen Sekse Sonja KlemsdalSammendrag
The apple fruit moth (Argyresthia conjugella) is a serious pest in apples. It is a specialist seed predator of rowan, but the females will lay eggs on apples when rowan berries are scarce. Olfaction is important for many insect species in locating host plants. The odorant detection results from the association of odorous ligands with specific olfactory receptors, which are located in the membrane of the olfactory neurons. The aim of this work is to identify and characterize the odorant receptor genes and the genes involved in the regulation of the circadian olfactory response rhythm in the female apple fruit moth. In order to identify ORs, and other genes involved in olfaction, in the apple fruit moth a library of mRNA up-regulated in the antenna compared to the legs was made using subtractive hybridization. So far 37 of the clones containing sequences that were found to be up-regulated in the antenna, out of in total 1045 clones, have been sequenced. BLAST searches were performed (BLASTx and BLASTn) to try to identify the transcripts. Those sequences that did not give a useful hit in the blast searches were translated to protein sequences in all six reading frames and the possible protein sequences were investigated for the presence of trans-membrane domains. The blast searches yielded useful hits for most of the sequences. 20 sequences were assigned to be probable odorant binding proteins and these seem to represent 12 different genes. Seven sequences were assigned to be glutathione S-transferases and 1 sequence were assigned to be cytochrome P450. Seven sequences gave no useful hits in the blast searches. These sequences seemed to represent 4 different genes and 2 of these have were predicted to contain transmembrane domains. These are possible odorant receptors.
Forfattere
Line RosefSammendrag
Questions: Could the seed bank increase biodiversity during restoration of abandoned, species-poor, formerly cultivated vegetation? Is it possible to identify how climate, soil and former and present management and vegetation affected the seed bank? Location: The study sites were eight abandoned grasslands, four in Orkdal, central Norway and four in Gaular, western Norway. Methods: 144 seed bank samples were collected from three depths. Each sample was sown and placed in a greenhouse. After three months, the trays were dried and stored at 4°C in a dry place for two months. This was repeated twice. Results: There was a separation of the two regions along the first DCA axis in both the seed bank and in the vegetation analysis and also a clear separation of the seed bank from the vegetation along the second axis. These results are caused by differences in former management as well as temperature, precipitation and soil type between Gaular and Orkdal. We found more annuals, short-lived species and species demanding light open conditions in the seed bank than in the vegetation probably because these species have the capacity for producing persistent seeds. Most of the species found only in the seed bank were found in very few samples and with few individuals. Conclusion: These results suggest that it may be difficult to increase vegetation biodiversity through restoration of grasslands such as those investigated if the natural soil seed bank is the main seed source.
Sammendrag
I Nordamerika og Europa har der siden 1980-erne været observeret misfarvede pletter på årsskuddenes nåle på nordmannsgran (Abies nordmanniana), nobilis (A. procera) og grandis (A. grandis). Skadebilledet ser ud til at være identisk, men optræder især på grandis og nobilis i USA og på nordmannsgran og nobilis i Europa. I USA har skaden været opfattet som fysiologisk og udløst af bestemte vejrforhold (Chastagner 1997). De første symptomer er lyse pletter på nålene kort efter udspring (figur 1). I løbet af sommeren bliver pletterne rødbrune (figur 2), og hele nålen kan blive nekrotisk og falde af (figur 3). Fænomenet har gået under navnet "røde nåle" i Danmark (Christensen 1981, Thomsen et al. 1997, Nielsen & Christensen 1997a, b) og "current season needle necrosis" (CSNN) i USA og Irland (Chastagner et al. 1990, Sinead 2000). Det var først efter 2000, at CSNN og "røde nåle" på nordmannsgran blev anset for at være identiske fænomener (Thomsen 2002). I Tyskland og Østrig har lignende skadesbilleder været koblet sammen med tilstedeværelsen af en svamp, som hedder Kabatina abietis (Butin & Pehl 1993, Perny et al. 2002, Lange 2007). Det tyske navn er Kabatina-Nadelbräune, dvs. brunfarvning af nåle. Illustrationerne i disse publikationer tyder på, at de omtalte symptomer er de samme, som vi kalder CSNN i det internationale juletræsmiljø. Dog understreger Kurt Lange, at man skal isolere svampen for at være helt sikker på diagnosen, samt at der ofte forekommer lignende symptomer uden svamp, således hyppigt i 2007 (pers. medd. i samtale under Langesømessen 2007). Blandt danske dyrkere har der også været en opfattelse af, at røde nåle kunne skyldes et svampeangreb. Dette er indtil nu blevet afvist af danske og nordamerikanske forstpatologer, som anser de forskellige, fremkommende nålesvampe for sekundære. Men mistanken er alligevel ikke helt ubegrundet, og det synes at være på tide at få sagen afklaret. Dette skal ske i et fælles dansk-norsk PAF projekt i samarbejde med andre lande.