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.
1998
Forfattere
Ricardo HolgadoSammendrag
Cereal cyst Nematodes Heterodera spp. are pests of cereal crops, and their occurrence is known for many years both in Europe and in Norway. This group of nematodes forms a complex of species referred to as the "Heterodera avenae-complex", this includes H.avenae Wollenweber (CCN), H. bifenestra Cooper, H. mani Matthews, H. iri Matthews, H. hordecalis Andersson, H. latipons Franklin and H. filipjevi Krall. The host status of cereal cultivars differs between and within different species of the H. avenae-complex, and several pathotypes occur in several species. The border lines for species and pathotypes of the Heterodera avenae-complex are diffuse. Several pathotypes of CCN are found in Europe, and two pathotypes Ha51 and Ha11 are reported from Norway, Symptoms of damage by cyst nematodes in cereals are usually shown as patches of pale and stunted plants. The effects on the aerial parts of plants are identical with symptoms of severe nitrogen and other mineral deficiencies. Plants attacked by the nematodes wilt readily in dry weather. This reflects the nematode damage to the root system. In our experience most modern commercial varieties of cereals are equally susceptible to CCN. The aim of the project is to study the occurrence and distribution of the species within H. avenae-complex, to clarify the pathotype spectrum and to investigate the possible occurrence of microbial antagonists in Norway. The project is expected to be completed in 2001.
Forfattere
Ricardo Holgado Christer Magnusson Bonsak HammeraasSammendrag
Soil samples from a growth depression in potato (cv. Saturna) yielded large numbers of root lesion nematodes Pratylenchus penetrans. Growth was greatly reduced in the center of the patch, but improved gradually towards the margins. Transect-sampling showed plant growth to be negatively correlated with densities of P. penetrans. The nematode density in the central part of the patch was 900/250g of soil, compared to 49/250 g of soil in the margins, where plant growth seemed unaffected. Our data suggest a threshold for damage of 100-250 P. penetrans per 250 g of soil. P. penetrans was present in roots, underground stems, stolons and tubers. In tubers nematodes occurred in the outermost 0.5 mm of the tissue. Common scab (Streptomyces spp.) occurred frequently, and P. penetrans was also present in tubers with scab. The nematodes were found around and inside cross-fissure lesions considered typical of Streptomyces. Saturna has a relatively high degree of tolerance against common scab. The high frequency of scab, and close association of the nematodes with the symptoms could indicate an interaction. This study suggests that Norway may have a new problem in potato production. Our study confirms that P. penetrans survives storage of seed potatoes, from which new infestations develop. Hence, tubers do appear to be an important means for the spread of P. penetrans to new areas.
Forfattere
Øystein Johnsen Bjørn Langerud Tone Skretting Torild Wickstrøm Gro Wollebæk Gro BehrensSammendrag
Det er ikke registrert sammendrag
Forfattere
Helge Sjursen Arild AndersenSammendrag
Det er ikke registrert sammendrag
Forfattere
Lita Greve Sverre KobroSammendrag
Det er ikke registrert sammendrag
Vitenskapelig – Presence of Phytphora fragariae var. fragariae in Norway
A. Stensvand, Maria Herrero
Forfattere
A. Stensvand Maria HerreroSammendrag
Det er ikke registrert sammendrag
Forfattere
Lars Olav Brandsæter Jan Netland Richard MeadowSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Svein Solberg Ingrid Ann Berg Knut Breivik Tone Groeggen Espen Moshaug Kjetil Tørseth Dan AamlidSammendrag
Det er ikke registrert sammendrag
Forfattere
Andries W. Boxman Kai Blanck Tor Erik Brandrud B. A. Emmett Per Gundersen Rene F. Hogervorst O. Janne Kjønaas Hans Persson Volkmar TimmermannSammendrag
Enhancement of the atmospheric N deposition is a serious threat for the structure and function of ecosystems. Here we evaluate the ecological effects of excess N with respect to changes in vegetation and soil biota in a series of experiments along a N gradient across Europe. The aim of this project (NITREX: N saturation EXperiments) is to assess the risk of N saturation and the reversibility of N saturation. At the experimental sites with a low-to-moderate input, N was added (n = 3), while at sites with a high input, N was removed by means of a transparent roof (n = 4). The experiments started between 1989 and 1991. Across the N gradient a positive correlation was found between the N concentration in deposition or soil solution with the N concentration in the needles and in general a negative correlation with the base cations K and Mg. In the N-addition plots there was a tendency towards a decreasing nutrient status of the needles, whereas at one site N-removal led to an improvement. Addition of N hardly affected fine-root biomass production, whereas signs of growth increase were recorded when the input was reduced. Tree growth was accelerated upon input reduction at two of three sites. Manipulation of N input did not alter the decomposition rate, although significant differences between sites were noted. Manipulation of the N input hardly affected the biomass of fungi and bacteria, but a negative relation between the N-addition and part of the soil fauna may be present among sites.