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.
2000
Forfattere
Leiv Mortensen Hans R. GislerødSammendrag
The effect of different air humidity levels on growth, keeping quality water loss, and nutrient concentrations of the rose cultivar "Souvenir"was studied in growth chambers in three different experiments
Sammendrag
A new white clover cultivar, Norstar, with excellent winter hardiness and good yield potential has been released (1999) for northern and upland parts of Norway. In a field experiment in Tromsø (690 39"N), the dry matter (DM) yield and persistence of Norstar in mixtures with different grass species was studied. The plots were subjected to simulated grazing or cut for silage, and fertilised with a yearly total of 60kg Nha-1. DM yields of the clover and grass components were determined during three growing seasons. The different grass mixtures had no direct impact on DM yield of clover, but in the first year the clover proportion of the total grass/clover yield was lower in mixture with timothy/meadow fescue than in mixture with smooth meadowgrass. However, in the following years the clover proportion of this mixture increased, whereas it declined in the mixture containing smooth meadowgrass. In 1999, the clover content in both mixtures was about 30%. Cutting regime had no influence on clover yield in either of the mixtures. Simulated grazing depressed the grass yield in white clover/timothy/meadow fescue mixtures, but not in white clover/smooth meadowgrass mixtures.
Forfattere
Ingerd Skow Hofgaard Leslie Wanner Anne Marte TronsmoSammendrag
Det er ikke registrert sammendrag
Sammendrag
Three commercial Trichoderma products (Trichodex, Binab TF WP, and Rootshield) and the laboratory strain T. harzianum P1 were sprayed weekly onto greenhouse-grown strawberry plants during the flowering period in an attempt to reduce fruit disease caused by Botrytis cinerea and Mucor piriformis. None of the treatments affected the marketable yield of strawberries. Laboratory tests showed that at the mean temperature of the greenhouse (12°C), formulated conidia of the various Trichoderma strains required up to 96 h to germinate, and conidia of B. cinerea and M. piriformis isolated from greenhouse strawberries required 11 and 16 h, respectively. Furthermore, the commercially formulated conidia were much more subject to fungistasis under nutrient stress in vitro than were fresh conidia of the same strains. The nutrient sensitivity was not revealed when assaying germination on a standard nutrient-rich laboratory medium. Formulated conidia were also inferior to fresh conidia in capacity to clonize senescent strawberry leaves.
Sammendrag
In the present study, the growth, dry matter partitioning and morphological characteristics and C exudation of two white clover cultivars, Norstar and AberHerald, were compared, under two temperature regimes (24/18°C and 12/6°C day/night) in a controlled temperature room. Root exudates collected from the two cultivars were also tested on two common soil types from northern Norway to determine the influence of the exudates on microbial activity in those soils. Plants grown at the higher temperatures had greater biomass and lower root:shoot ratio than those grown at the lower temperature regime. The plants growing in the higher temperature regime had a higher N content and concentration. Temperature significantly affected morphological characters and plants grown at the higher temperature had more leaves and growing points, and longer stolons than those grown at 12/6°C. Total organic C in the root exudates was determined on two occasions during the experiment. After 7 days, the concentration in the leachates from the plants at the higher temperature was significantly greater, but after 34 days, the concentrations were much more variable from plant to plant and no significant differences were seen. There were no significant differences in the rate of O2 uptake and utilisation by either the peat or mineral soils given exudates collected from plants growing at the cooler temperatures. In soils which were given exudates collected from plants growing at the higher temperatures, the rate of O2 utilisation by the mineral soil given the Norstar exudates was significantly lower than the other three combinations.
Forfattere
Leiv MortensenSammendrag
The short-day plants Begoniaxcheimantha, Chrysanthemum morifolium (one pot and one cut cultivar), Euphorbia pulcherrima (poinsettia) and Kalanchoe blossfeldiana were grown at vapour pressure deficits (VPDs) of 155, 420 and 660 Pa (corresponding to 93, 81 and 70% relative air humidity, respectively). Growth, flowering, keeping quality and water relations were tested
Forfattere
Per Holm Nygaard Heleen A. de WitSammendrag
Elevated concentrations of aluminium (Al) which have been hypothesized to limit root growth of forest trees as well as nutrient uptake, are believed to be a major threat to forest vitality. Direct toxicity of Al, causing decreased root growth has been observed in several nutrient solut ion studies and in some pot experiments using seedlings.However, direct support for the occurrence of decreased root growth in mature forest stands is scarce. Despite the uncertainty concerning effects of ambient concentrations of Al in soil water on fine roots, the concentrations of dissolved Al in forest soils has been assigned a key role in models used to calculate critical loads.Here we present results of three years of artificial additions of Al on fine root growth in a mature stand of Norway spruce (Piece abies). During the growing season the average concentrations of dissolved inorganic in soil water at 10-cm soil depth ranged from about 1 mol L-1 (control) to 120 mol L-1 (highest Al treatment).According to nutrient solution studies the established concentrations of dissolved inorganic Al reached levels that may be toxic. In addition, the Ca/Al ratios were well below 1.0, a value, which is regarded as a lower limit below which negative effects on vegetation may be expected.So far, no effects on fine root growth, root mortality and root distribution has been observed. Chemical analysis of the fine roots indicate a lower molar Ca/Al ratio in living fine roots of 0-20 cm depth and dead fine roots 0-40cm in the Al treatments compared to controls.Our study does not support the critical load assumption that Ca/Al 1 in soil solution is critical to fineroots, as shown by some culture solution experiments. The molar Ca/Al ratio of fine roots mainly reflect the soil chemical composition, which has a steep depth gradient So far, three years of Al additions has shown that the soilmatrix is an extremely robust growth medium, which can sustain high inorganic Al concentration and low Ca/Al ratios.The results show clearly that the value of Ca/Al or BC/Al as used in critical load calculation and plant soil modeling, may have to be reconsidered.
Forfattere
Jan Mulder J.F. Gallardo Lancho E. Matzner Edward Tipping Charlotte Bryant Nicholas Clarke S. Lofts B. Michalzik A. Vicente EstebanSammendrag
Det er ikke registrert sammendrag
Forfattere
Bjørn MoltebergSammendrag
I forbindelse med jordbruksoppgjøret i 1999 var hele tilskuddsordningen med endret jordarbeiding oppe til diskusjon. Under forarbeidet til jordbruksoppgjøret ble Planteforsk Apelsvoll bedt om å vurdere de ulike tiltakene som ordningen omfatter, med tanke på miljøeffekter og andre effekter. Dette arbeidet resulterte i en intern utredning til Landbruks-departementet i juni 1999. I ettertid har Landbruksdepartementet ytret ønske om å mangfoldiggjøre utredningen slik at den kan være tilgjengelig for landbruksforvaltningen i fylker og kommuner, samt rådgivningstjenesten. Tanken er at den skal fungere som bakgrunnsstoff for de som skal praktisere tilskuddsordningen på det lokale plan. Det er den siltrike jorda som er mest utsatt for erosjon, og erosjonsrisikoen avtar med økende andel organisk stoff. Jord og P-tapet kan rangeres etter jordarbeiding på følgende måte, der høstpløying gir størst tap og overvintring i stubb gir minst: Høstpløying>Vanlig sådd høstkorn>Høstharving>Direktesådd høstkorn> Overvintring i stubb En kan trolig regne med at 1,0-3 kg N/daa går tapt gjennom vinterhalvåret i kornområdene på Østlandet og Trøndelag, men at N-tapet er svært påvirket av nedbør, temperatur, jordart og avling. Lette jordarter vil ofte ha større N-utvasking, selv om mineraliseringen og innholdet av organisk N er større på leirjord. Ut fra forsøk og tidligere undersøkelser vil trolig stubbarealer, direktesådde arealer eller lett høstharva arealer ikke redusere N-utvaskingen med mere enn 0,5 - 1,0 kg N/daa eller 15-30 % i forhold til normalt pløyde arealer. Ugrasmengden og problemer knyttet til ugras øker jo mindre jorda blir bearbeidet, men disse problemene kan reduseres med økt bruk av glyfosat. Uten bruk av glyfosat vil det på mange arealer være svært vanskelig å drive plogfri jordarbeiding over tid. Når det gjelder sjukdommer og skadedyr og dyrkingsproblemer knyttet til dette ved endret jordarbeiding, er ikke bildet like klart, men også her finnes klare tendenser til økt risiko for fusariumsmitte, økt sprøytebehov mot snømugg i høstkorn og økt risiko for bladflekk-sjukdommer ved dyrking av samme art flere år. Avlingene vil påvirkes av at jordforholdene og ugrasmengdene endres ved endring i jordarbeidingspraksisen. Det er ikke lett å skille disse faktorene fra hverandre. Halm, nedbør, lengde på vekstsesongen og lave middeltemperturer vil også påvirke avlingene når en skal praktisere ulik jordarbeiding. Bruk av fangvekster er et godt tiltak for å hindre erosjon og N-utvasking. For metoden "lett høstharving" er det halmmengdene som avgjør harveintensiteten. Det å differensiere og ha et fleksibelt virkemiddelsystem er en riktig vei å gå, men dette kan gi kompliserte systemer. Problemet er som nevnt at virkning på avling, ugras, erosjon og avrenning av næringsstoffer vil være forskjellig for de ulike tiltakene når jordtypen og klimafaktoren endres
Forfattere
Tonje Økland Rune Halvorsen ØklandSammendrag
Det er ikke registrert sammendrag