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.
2004
Forfattere
David Gadoury Robert C. Seem William E. MacHardy Wayne F. Wilcox David A. Rosenberger Arne StensvandSammendrag
Maturation and release of ascospores of Venturia inaequalis was assessed at Geneva and Highland, New York; and at Durham, NH. Airborne ascospore dose was monitored at each location by volumetric spore traps. Maturation and discharge of ascospores at each location was also assessed by microscopic examination of crushed pseudothecia (squash mounts). Additional assessments were made at New York locations to quantify release from leaf disks collected weekly from orchards (discharge tests). Finally, ascospore maturity was estimated for each location by a degree-day model developed in an earlier study. Ascospore maturation and release as measured by squash mounts and discharge tests lagged significantly behind cumulative ascospore release as determined by volumetric spore traps. The mean date of 98% ascospore discharge as determined by squash mounts or discharge tests occurred from 20-30 days after the mean date on which cumulative ascospore release had been detected by volumetric traps. Cumulative ascospore maturity estimated by the degree-day model was highly correlated (r2 = 0.82) with observed cumulative ascospore release as monitored by the volumetric traps. Although large differences between predicted maturity and observed discharge were common during the exponential phase of ascospore development (125 to 350 degree days after the occurrence of the green tip stage of apple fruit buds), the date of 98% cumulative ascospore maturity predicted by the model was generally within 1 to 9 calendar days of the date of 98% cumulative ascospore release as determined by the volumetric traps. Cumulative ascospore discharge as monitored by the volumetric traps always exceeded 98% at 600 degree days after green tip. Estimating the relative quantity of primary inoculum indirectly by means of a degree-day model was more closely aligned with observed ascospore release, as measured by volumetric traps, than actual assessments of ascospore maturity and discharge obtained through squash mounts and discharge tests.
Forfattere
H. Schmidt A. Adler A. Holst-Jensen Sonja Klemsdal A. Logrieco R.L. Mach H.I. Nirenberg U. Thrane M. Torp R.F. Vogel T. Yli-Mattila L. NiessenSammendrag
An integrated systematic study was carried out to clarify the taxonomical position and relationship of Fusarium langsethiae to other taxa within the Fusarium section Sporotrichiella. Strains of this species were compared with strains of the closely related species Fusarium poae and Fusarium sporotrichioides using a composite dataset. This set consisted of DNA sequences derived from the ribodsomal internal transcribed spacer (ITS) regions, partial sequences of the ribosomal intergenic spacer (IGS) region, the ß-tubulin and translation elongation factor-1 alpha (EF-l") genes, AFLP fingerprints, chromatographic data on secondary metabolites and morphological data and growth chharateristics. From these combined data, a consensus matrix was calculated by taking the mean of all pairwise distances between single isolates over all separate datasets. The consensus matrix was used as the basis for the construction of a UPGMA dendrogram and a multidimensional scaling, both of which revealed a clear separation of the three taxa. Partial IGS, EF-l" and ß-tubulin sequence - as well as chromatography - and AFLP-derived similarities turned out to be comparably consistent, while ITS sequence- and morphology-derived similarity matrices were rather divergent.
Forfattere
Jens Rohloff Rolf Nestby Johannes A. Folkestad Tor-Henning IversenSammendrag
Dyrking av dryppvatnet jordbær (Fragaria ananassa Duch.) under regntak ble undersøkt i tre forsøksfelt i Midt-Norge, ved Steinkjer (1999), Lensvik, Agdenes (2000) og ved Plantebiosenteret, Trondheim (2001-2002). Hovedmålet var å undersøke hvilket potensial regntak har for å unngå en massiv infeksjon av gråskimmel (Botrytis cinerea) på jordbærfruklten, som ofte skjer som en effekt av mye regn under sesongen midtsommers. Som en del av det treårige prosjektet ble det i det første året undersøkt parametre på smakskvalitet som løselig tørrstoff, pH og titrerbar syre. I tillegg ble innholdet av flyktige aromastoffer undersøkt med "headspace solide-phase microextractin" (HS-SPME) og gasskromatografi koblet med massespektrometri (GC-MS). Lysintensiteten (PAR) ble dramatisk redusert under regntaket ved overskyet og solfylt vær henholdsvis med 21% og 50% i Lensvik og 26% og 47% ved Plantebiosenteret. Imidlertid var parametrene for temperatur og luftfuktighet uendret. Innholdet av løselig tørrstoff og titrerbar syre for jordbær dyrket under regntak var litt redusert men forskjellene var ikke signifikante. HS-SPME studiet viste at biosyntesen av flyktige aromastoffer i jordbær som hørte til den kjemiske gruppen estere, ble litt redusert under regntak. Optimale klimatiske forhold i sommeren 2002 førte til danning av jordbær rik på karakteristiske flyktige stoffer (Plantebiosenteret). Detaljerte aromaprofiler fra hele sesongen, bekreftet variasjonen av noen stoffer med inflytelse på aroma, med avtagende nivåer av aldehyder (hexanal, (E)-2-hexanal) og økende konsentrasjoner med estere (metyl acetat, etyl butanoat, hexyl butanoat, etyl hexanoat) og mesifurane, et av de karakteristiske aromastoffene i jordbær. I kontrast til dette ble de summerte nivåene av esterifiserte aromakomponenter nesten ikke endret under regntak. Konklusjonen er at jordbærsmak og aromasammensetting og derved den omsettbare fruktkvalitet, ble bare ubetydelig påvirket av dyrking under regntak som en effekt av endrede dyrkingsforhold.
Sammendrag
Sweet cherry trees sometimes suffer from dieback symptoms under Scandinavian growing conditions. Some combinations of cultivars and rootstocks are more susceptible to this than others. The graft union between a rootstock and a scion is a junction between two different tissues. Differences in tissue development in the union may provide a mechanistic explanation of inhibiting transport of water and nutritional substances and likely inhibit growth of the scion. In order to investigate the relationship between growth and the amount of functional xylem tissue of potted sweet cherry trees, an experiment was conducted during 2002-2003. One year old field budded and bench grafted (from green house) sweet cherry trees of the cultivars Van, Ulster and Lapins in all combinations of the three rootstocks Prunus avium seedling, Colt and Gisela 5 were grown in pots for two growing seasons. After shoot extension had terminated when trees were in full leaf the second year, the total growth of the different parts of the trees and the quantification of functional area using safranin staining were conducted. The total mass production (tree dry weight, the length of two year old wood and number of leaves) was significant larger in the budded trees. Similarly the trunk cross sectional area was significant larger 10 cm above and in the middle of the graft union, but not 10 cm below. The Colt trees were the most vigorous followed by the seedling and Gisela 5. Small differences between the different cultivars were registered. Xylem staining with aqueous safranin combined with quantitative image analysis showed that the rootstock stem had a higher proportion of stained tissue than the scion stem. Sections taken in the middle of the graft tissue and above showed that the proportion of stained tissue declined proportionally with the distance from the roots. The total area of stained stem xylem was larger for the two vigorous rootstocks compared to Gisela 5. Small differences were observed between cultivars and propagation methods.
Forfattere
Tor Håkon SivertsenSammendrag
The main idea of this paper is taking a step towards clarification of the scope of the concept of continuity of continuum mechanics, when this concept ought to be used. Mathematics is in an auxiliary way defined as a formal extension of mans ability to compare, aggregate and divide aggregates of objects in the physical world. Then the formal mathematical concept of continuity of the real line is discussed, and the conclusion is that according to the definition of mathematics used, there exist no continuous physical medium what so ever. Then the concepts of continuity and discontinuity have no meaning for any physical medium beyond the possibility of making measurements of defined parameters. Literature: Brown, David, 1997, An Introduction to Object-Oriented Analysis, John Wiley and Sons. INC, New York, 700pp Cohen, P.J., 1963, The Independence of the Continuum-Hypothesis, Proc. Nat. Acad. Sci. U.S.A. 50, 1143-1148 Devlin, Keith ,1993, The Joy of Sets, Fundamentals of Contemporary Set Theory, Springer-Verlag New York Berlin, 192 pp Gödel, K., 1940, The Consistency of the Continuum-Hypothesis, Princton, NJ: Princton University Press Rudin, W., 1964, Principles of Mathematical Analysis, McGRAW-HILL BOOK COMPANY, New York San Fransisco Toronto London, 270 pp. Sivertsen, T.H. ,2004, Discussing scientific methods and the quality of meteorological data, part of a report to be published by COST 718 ACTION( `Meteorological Applications for Agriculture"), 19 p ( In press)
Sammendrag
Trees of `Discovery" apples growing on dwarf and semi-dwarf rootstocks were assessed in field trials at two sites (western and eastern Norway) at 60° North. The rootstocks included two selections of M.9 (EMLA, RN.29), two from the Polish (P) series (P.59, P.60), three from the Geneva (G) series (G.30, G.78730-026, G.202) and M.26. Trees were planted in the spring 1997 as two years old feather trees, spaced 1.5 x 4 m, trained as slender spindles and evaluated for five subsequent years. Soil management were grass in the alleyways and herbicide strips 1-m wide along the tree rows. Tree size was significantly affected by the rootstocks after five years growth. P.59, G.78730-026 and M.9 RN.29 produced the smallest and G.30 and G.202 the largest trees as measured by trunk cross-sectional area. P.59 and G.30 had the greatest yields per tree, followed by G.202, P.60 and M.9 EMLA. Trees on P.59 were the most yield efficient followed by the two M.9 clones. The fruit density measured as number of fruits per trunk-cross-sectional area showed similar results. The different rootstocks affected little the fruit weights. Fruit quality characterized by the content of soluble solids was in general high and did not differ between trees on the various rootstocks.
Forfattere
Mekjell Meland Magne Eivind MoeSammendrag
The performance of the plum rootstocks Marianna, Pixy and Wangenheim using St. Julien A as a standard to the cultivars Avalon, Edda, Excalibur, Jubileum, Reeves and Victoria Naa was assessed in a field trial at western Norway at 60° North. Trees were planted in spring 1999 and evaluated for the five subsequent years. The plant material was one year old whips, spaced 2.0 x 4.5 m and formed with a central leader as free spindles. Soil management were grass in the alleyways and herbicide strips 1-m wide along the tree rows. Tree size was significantly affected by the rootstocks after five years growth. Wangenheim produced the smallest and St. Julien A and Pixy the largest trees as measured by trunk cross-sectional area in average for the different cultivars. Pixy produced the largest yields per tree to the cultivars Edda, Excalibur and Reeves while St. Julien A was the most productive to Avalon, Jubileum and Victoria Naa. Trees on Pixy were the most yield efficient for all cultivars with the exception of Victoria Naa. The fruit sizes were in general large, but became affected by the different rootstocks to some extent. Depending on the cultivar, fruit size was favourable affected by Pixy and St. Julien A, while trees on Marianna produced the smallest fruits. Fruit quality characterized by the content of soluble solids was in general high and did not differ between trees on the various rootstocks. The cultivar Avalon had the largest amounts of soluble solids.
Forfattere
Mekjell MelandSammendrag
Alternate bearing is a major problem for the Norwegian apple industry. Due to over-cropping one year where fruit size and quality are reduced, the trees are likely to turn into a pattern with high and low yield every second year. This inconsistent yield pattern provides problem for both the growers and the market. Commercial practise is to remove the excessive flowers or fruitlets by chemicals or by handthinning. The only officially registered agents for apple thinning are ethephon and ammoniumthiosulphat. The growers find them unpredictable in use and more knowledge is wanted in order to give more precisely thinning recommendations. A new project started at Ullensvang Research Centre in 2003. It will last for three years and focus on optimising the crop loads and test different thinning agents under bloom and at different fruitlet stages. Different crop levels will be established during and after bloom by hand adjusted by trunk cross sectional area. The experimental trees will be monitored during a 3-year period. Traditional pomological observations will be registered included storage of the fruits where fruit quality will be measured. Leaf areas per tree will be calculated using an area meter. In addition different thinning chemicals will be tested according the program to the working group of European Fruit Research Institute Networks. Emphasis will be put on concentration and thinning periods of the agents ethephon, ammoniumthiosulphat and compounds that could be approved for organic growing like colza oil. Results from the 2003 season will be presented.
Sammendrag
Lilte forskning er gjort på forsvinning av plantevernmidler under kalde klimaforhold, og det er et behov for å fokusere på effekten av klima på nedbrytning av plantevernmidler i jord. Glyfosat er et ugrasmiddel som er mye brukt for å kontrollere flerårig ugras ved sprøyting etter innhøsting. Effekten av fryse-tine aktivitet på tilgjengeligheten av glyfosat i jord, og dermed muligheten for mineralisering av mikroorganismer i jord, er undersøkt ved inkubasjon av forstyrra jordsøyler i lab etter behandling med 14C-merka glyfosat, under ulike temperaturregimer. Vintersimuleringene inkluderte konstant tint jord (+5°C), konstant frost ("5°C), ustabile forhold med korttidsfluktuasjoner (24t ved -5°C fulgt av 24t ved +5°C), og langtidsfluktuasjoner (3u ved -5°C fulgt av 3u ved +5°C). Fordelingen av 14C-glyfosat ble fulgt gjennom inkubasjonsperioden ved måling av mineralisert glyfosat (14CO2), glyfosatkonsentrasjonen i jordvann, KOH-ekstraherbart glyfosat, og ikke-ekstraherbart glyfosat. De mikrobielle jordegenskapene som ble brukt for å karakterisere jorda var estimater av størrelsen på den mikrobielle biomassen i jord, mikrobielt aktivitetsnivå, og mikrobiell diversitet.
Forfattere
Marianne StenrødSammendrag
Dette arbeidet er gjort innenfor rammene av det strategiske instituttprogrammet "Plantevernmidler i miljøet", hvor målet var å studere forsvinningsbilde av plantevernmidler og transportprosesser i jord under ulike klimatiske betingelser, med spesiell vekt på nordiske forhold. Hovedmålet med denne undersøkelsen var å øke kunnskapsgrunnlaget om effekten av lave temperaturer og fryse-tine aktivitet på mineraliseringen av glyfosat i jord. Delmålene omfattet blant annet å finne fram til eventuelle relasjoner mellom klimaet en jord med spesifikke fysiske, kjemiske og biologiske egenskaper er utviklet under, og den biologiske nedbrytningen av glyfosat under ulike klimatiske forhold. Vi vurderte også disse resultatene i forhold til den naturlige variasjonen i noen spesifikke mikrobielle jordegenskaper. Resultatene viser at glyfosat brytes ned via mikrobielle prosesser i jord, og at temperatur er en viktig regulerende faktor. Den mikrobielle aktiviteten var lav men målbar ved temperaturer under 0°C, og ved tining av jorda steg aktiviteten raskt og nedbrytningen av glyfosat kom raskt i gang. Dette viser at vi har et potensiale for nedbrytning av glyfosat i jord under frostfrie perioder gjennom vinteren. Arbeidet omfattet laboratorieundersøkelser av jordprøver fra forsøksfelt med sandig silt/sandig lettleire i Sully s/Loire (Vest-Frankrike), Grue (Sørøst-Norge), og Målselv (Nord-Norge), for å avdekke forskjeller pga. klimatisk opphav. Hovedforskjellene lå imidlertid i jordprøvenes kapasitet for binding av glyfosat og i forskjeller i det mikrobielle samfunnet - to svært viktige faktorer for nedbrytning av glyfosat i jord. Resultatene kan hovedsakelig brukes for å anslå nedbrytningshastighet for glyfosat i kaldt klima i toppjord som pløyes og harves årlig. Videre gir resultatene en indikasjon på hvordan plantevernmidler med tilsvarende fysiske og kjemiske egenskaper vil oppføre seg i jord; det vil si plantevernmidler som brytes raskt ned når de er tilgjengelige for mikroorganismer, men som bindes raskt og sterkt i mineraljord.