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.
2009
Forfattere
Belachew Asalf Arne Stensvand David M. Gadoury Robert C. Seem Andrew Dobson Anne Marte TronsmoSammendrag
Development of ontogenic resistance to powdery mildew (Podosphaera aphanis) in strawberry fruit has not been quantified, and thus cannot be exploited in disease management programs. Four commercially-relevant strawberry cultivars were evaluated for ontogenic resistance to powdery mildew. Fruits were inoculated at one of the four growth stages: flowering, green, white and early pink fruit. There was a significant difference between and within cultivars at the bloom and green stage of inoculations (P ≤ 0.05) for both disease incidence and severity. On average 16.4, 39.5, 48.7, and 60.3 % of the fruits inoculated at bloom developed powdery mildew in cultivars Elan, Korona, Frida and Inga, respectively. None of the cultivars developed powdery mildew when inoculated at the pink stage. It may be concluded that flowers and green fruits of strawberry were much more susceptible to powdery mildew infection than white and pink fruits. The high susceptibility of cultivars at the flower and early green stages seemed coincident with the succulent nature of the fruits at these stages, making it easy for penetration and establishment of mildew. Control measures targeting at these critical windows of fruit susceptibility are likely to reduce yield loss.
Forfattere
Robert C. Seem Arne Stensvand David M. Gadoury Håvard Eikemo Andrew Dobson M. Catherine HeidenreichSammendrag
The objective of this work was to investigate how primary disease levels of powdery mildew (Podosphaera aphanis) in strawberry (Fragaria × ananassa) influence disease development in time and space. Experiments were repeated over two seasons in field trials in Norway (Ås, cv. Korona) and USA (Geneva, NewYork, cvs. Earliglow and Elan). Five-row plots of 50 to 100 mildew-free plants (planting distance 0.45 x 1.2 m) were established each year within large grain fields, with a minimum distance of 90 m between plots, and no fungicide treatments. At start of the experiments, plants at the center of each plot were inoculated with 0, 1, 10, or 100 mildew-infected leaflets. Uninoculated plots developed only trace levels of powdery mildew, despite nearby diseased plots. More rapid and severe disease development was observed in the inoculated plots; e.g., mildew was observed on 31, 36, 311, and 912 leaflets in the 0, 1, 10, and 100 plots, respectively, in Norway in year 1 of the trial. Within the plots, disease development was highest close to the inoculum source and downwind from the prevailing wind. It may be concluded that in the absence of nearby sources of contamination, disease severity in strawberry plantings is determined by the dose of initial inoculum resident within the planting. The practical impact of the trials was to demonstrate long-lasting benefits of clean, mildew-free planting stock in commercial strawberry production, even in areas where the pathogen is endemic and the environment is very conducive to disease.
Sammendrag
Results from the study "Effects of metabolic changes during cold hardening on freezing survival of Agrostis spp." were presented. The objectives of the trial were: (1) to compare freezing tolerance of velvet bentgrass and creeping bentgrass, (2) to quantify carbohydrate and protein changes during the two consecutive phases of cold acclimation in these species, and (3) to compare one direct and two indirect methods for determination of LT50 in turfgrasses. Four treatments representing different phases of cold acclimation were compared: (i) non-acclimated (NA) plants maintained at 18 / 12 °C (day/night); (ii) plants acclimated at 2 °C for 2 wk (A2); (iii) plants acclimated at 2 °C for 4 wk (A4); and (iv) plants acclimated at 2 °C for 4 wk with an additional sub-zero acclimation in the dark at -2 °C for 2 wk (A4+SZA2). Velvet bentgrass and creeping bentgrass showed no difference in lethal temperatures for 50% of the test population (LT50) as estimated by whole plant survival. Treatments A2 and A4 resulted in accumulation of sucrose and fructans, and significantly lowered LT50 as compared with NA. A4+SZA2 resulted in less fructans, no difference in sucrose and higher concentration of reducing sugars but LT50 was not lower than after A4 treatment. Crown viability determined by reduction of tetrazolium chloride showed close correlation with LT50 values based on whole plant survival. Electrolyte leakage produced less consistent results and cannot be recommend as a quick method for evaluation of relative hardiness of the rather small crowns of bentgrass species, especially not if acclimation at subfreezing temperatures is part of the testing procedure.
Forfattere
Tatsiana EspevigSammendrag
Preliminary results from the study "Effects of metabolic changes during cold hardening on freezing survival of Agrostis spp." were presented. The objectives of the trial were: (1) to compare freezing tolerance of velvet bentgrass and creeping bentgrass, (2) to quantify carbohydrate and protein changes during the two consecutive phases of cold acclimation in these species, and (3) to compare one direct and two indirect methods for determination of LT50 in turfgrasses. Three (of four) treatments representing different phases of cold acclimation were compared: (i) nonacclimated (NA) plants maintained at 18 °C/12 °C (day/night); (ii) plants acclimated at 2 °C for 2 wk and 250 μmol m-2 s-1 for 12 h photoperiod (A2); and (iii) as treatment (ii) but for 4 wk (A4). Plants exposed to additional sub-zero acclimation in the dark at -2 °C for 2 wk (A4+SZA2) were under acclimation treatment at that time. Results regarding 1st and 3rd objectives were discussed. Acclimation at 2 ºC significantly improved freezing tolerance of both species, but differences between species were not significant. The LT50 for plants subjected to A2 and A4 were 4 and 6 °C lower, respectively, compared to NA plants. Crown viability test had a good correlation with the LT50 based on whole plant survival. Electrolyte leakage underestimated freezing survival ability in Agrostis spp.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Tatsiana EspevigSammendrag
One of the major concerns for the use of velvet bentgrass (Agrostis canina) in Scandinavia is whether current cultivars have sufficient winter hardiness. To meet this challenge, velvet bentgrass (VB) cultivars were tested for winter hardiness in controlled environments at UMB during 2006/2007. Hardened and unhardened VB cultivars Avalon, Villa, Greenwich and Legendary were compared with creeping bentgrass (CB, Agrostis stolonifera) cv. Penn A-4 (control) for freezing tolerance. There were no differences in freezing tolerance between velvet and creeping bentgrass, but none of the tested cultivars, whether hardened or not, tolerated freezing to - 9 ºC or lower.That became a background for the collaborative project between the Norwegian Institute of Agricultural and Environmental Research (Bioforsk), Norwegian University of Life Science, Rutgers University and the University of Massachusetts. The objectives of the project would be: (1) to compare freezing tolerance of VB and CB, (2) to quantify carbohydrate changes during the two consecutive phases of cold acclimation in these species, and (3) to compare one direct and two indirect methods for determination of LT50 in turfgrasses.
Forfattere
Nils VagstadSammendrag
Det er ikke registrert sammendrag
Sammendrag
Forsøk med oppfôring av kopplam etter to ulike strategier viser at produksjon av kopplam med bruk av melkeerstatning og kraftfôr generelt er lite lønnsomt. Det er beregnet et forventet "overskudd" per kopplam på bakgrunn av utgifter til melkeerstatning og kraftfôr de første syv ukene (tabell 1) og utgiftene til kraftfôr i beiteperioden fram til slakt. "Overskuddet" er beregnet til ca 173 kr og 53 kr hhv i 2007 og 2008. Det er i beregningene ikke tatt hensyn til alle utgifter som vaksiner, smokker, flasker, strø og arbeid. Det kan være aktuelt å se på andre former for framfôring som for eksempel en mer moderat tildeling av kraftfôr i beiteperioden (400-500 g per dyr per dag) og eventuelt bruk av annen type beite enn vanlig eng. Mer forskning må til før det er mulig å konkludere med lønnsomheten i norsk kopplamproduksjon.
Forfattere
Vibeke LindSammendrag
The general aim of this thesis was to gain more knowledge on how the sensory profile and fatty acid composition of meat from lambs were affected when lambs were finished on concentrate and roughage or different types of pastures. The different types of pastures were mountain pastures, cultivated pastures, ryegrass pastures and semi-natural pastures. The effect of gender on meat quality was examined as well. To evaluate the effects of these factors, three studies were performed.In the first study (Paper I) the sensory profile and fatty acid composition in meat from lambs slaughtered directly from unimproved mountain pastures was compared with meat from lambs raised on unimproved mountain pastures and fattened on biodiverse cultivated pastures for 26, 39 and 42 days, respectively, before slaughter. This experiment was conducted at two different locations in Norway in 2006 and 2007, with a total of 124 Norwegian White Sheep (NWS) lambs. Loin samples of M. Longissimus dorsi from lambs above a live body weight of 40 kg were selected and analysed for sensory attributes, and fatty acid composition was determined in the subcutaneous fat over the Longissimus dorsi. Significant differences were found in the sensory attributes of hardness, tenderness, fattiness, metallic and rancid flavour, and in the polyunsaturated fatty acid content between the two treatments.The effects of the different production systems on sensory attributes and fatty acid composition were examined in the second study (Paper II). 150 NWS lambs grazed on the same semi-natural lowland pasture with their dams for three months or more. The effect of pre-slaughter fattening on meat quality was compared using a control group of lambs slaughtered directly from the pasture. Four pre-slaughter treatments were established: weaning and indoor-feeding on concentrate and grass silage for either 44 or 24 days before slaughtering (Conc44, Conc24), and grazing on ryegrass pasture for the same periods (Rye44, Rye24). Loin samples of M. Longissimus dorsi including the subcutaneous fat over the muscle from 15 carcasses from each treatment were analysed for sensory attributes and fatty acid composition. A lower intensity of acid taste was observed in meat from lambs in treatment Conc44 compared with meat from lambs in the control treatment. A higher content of the fatty acids C16:0, C18:1n-9 and C18:2n-6 and the n-6/n-3 ratios was related to meat from lambs fed concentrate, while a higher content of the fatty acids C18:0, C18:1t-11 and C18:3n-3 was found in meat from grazing lambs. In the third study (Paper III), the effect of gender and feeding on the fatty acid composition and sensory profile of meat from NWS lambs was investigated. Lambs from the 2006 treatment in Northern Norway in Study I were used in the first experiment including 22 female and 22 male lambs. In addition, all lambs from Study II, including 46 female and 29 male lambs, were used in the second experiment. Loin samples of M. Longissimus dorsi were analyzed for sensory profile and fatty acid composition. All lambs were slaughtered in September. There were no significant differences in sensory profile between lambs in experiment 1, while in experiment 2, meat from male lambs had higher scores for cloying and rancid flavour and lower scores for sour and sweet taste compared to meat from female lambs. The main conclusions from the present study are that finishing lambs on cultivated pastures can alter the sensory profile and fatty acid composition acquired on mountain pastures to a small degree. Finishing lambs indoors on concentrate and roughage can also alter the fatty acid composition in the meat compared to meat from lambs that graze on semi-natural pastures during the summer. The differences in sensory profile between genders in favour of the meat from female lambs indicate that females may be prioritised over males and off-season fresh meat should preferably be produced from female lambs. Furthermore, male lambs should be given the optimum conditions to be prepared for slaughter early in the season thereby reducing the risk of quality problems. Meat from lambs that is not ready for slaughter when gathered from natural and semi-natural pastures in the autumn should be marketed separately.
Forfattere
Lise GrøvaSammendrag
foredrag på Erfaringskonferanse for Beiteprosjektene i 2009