Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2009
Abstract
Regulation of flowering time in Arabidopsis thaliana is controlled by a network of pathways integrating environmental and internal signals. Two of these pathways, the vernalization and photoperiodic pathways, mediate responses to prolonged cold period and photoperiod, respectively. A number of A. thaliana populations from high-latitude and high-altitude locations in Norway were collected and phenotyped for flowering time in response to 5 photoperiods and 5 vernalization treatments. Vernalization and photoperiodic sensitivity were not correlated with latitude but rather with climatic factors such as winter temperature and precipitation that do not vary with latitude, especially in coastal environments. Coastal populations, both from subarctic and intermediate latitudes, were rather insensitive towards the length of the vernalization treatment but very sensitive towards differences in photoperiods. Stronger photoperiod sensitivity in coastal populations might be a necessary adaptation for sensing the onset of spring in regions with relatively mild and unpredictable winter climates as opposed to continental climates with more stable winters. FLC sequence variation was only partly associated with vernalization response, whereas variation in transcript levels of CRY2, TOC1 and GI was correlated with photoperiodic responses. This suggests that local adaptation of populations may be partly mediated by photoreceptors and circadian clock pathways.
Authors
Anna Lewandowska-Sabat Siri Fjellheim Per Winge Atle M. Bones Torfinn Sparstad Carl Gunnar Fossdal Jorunn Elisabeth Olsen Odd Arne RognliAbstract
No abstract has been registered
Authors
Hallvard JensenAbstract
No abstract has been registered
Abstract
One of the major concerns regarding use of velvet bentgrass in Scandinavia is whether current cultivars are sufficiently tolerant to frost. In 2008-09 the four velvet bentgrass (VB, Agrostis canina L.) cultivars Avalon, Greenwich, Legendary, and Villa, and the creeping bentgrass (CB, Agrostis stolonifera L.) cultivar Penn A-4 (control) were established from seed in 7.5x10x10 cm pots filled with a USGA-spec. sand containing 0.5% (w/w) organic matter. The following four treatments representing different phases of cold acclimation were compared: (i) nonacclimated (NA) plants maintained at 18 °C/12 °C (day/night) and 16 h photoperiod (150 μmol/m/s); (ii) plants acclimated at 2 °C and 16 h photoperiod (250 μmol/m/s) for 2 wk (A2); (iii) plants acclimated as ii plus 2 wk of sub-zero acclimation in darkness at -2 °C (A2+SZA2); and (iv) naturally acclimated plants under outdoor (field) conditions in November -December (FA). Freezing tolerance was assessed visually as percent of pot surface covered with healthy turf after 26 days of recovery in the greenhouse. To examine the relationship between physiological changes under cold acclimation and freezing tolerance, crowns of VB and CB were harvested for carbohydrate (CHO) analysis after each hardening treatment. Results showed that FA plants survived all freezing treatments (plant coverage more than 90 %). A2+SZA2 plants had better survival after freezing to -9 °C, -12 °C and -15 °C as compared with A2 plants. Differences in freezing tolerance between VB and CB were not significant. NA plants survived none of freezing temperatures. The predominant CHO in VB and CB crowns were sucrose and fructans. Compared with NA plants, A2 plants had significantly higher concentrations of fructose, sucrose and fructan. Exposure to -2 ºC in darkness (A2+SZA2) had no further effect on these concentrations. Natural hardening (FA) resulted in total carbohydrate and fructan concentrations significantly lower than for plants exposed to artificial acclimation.
Abstract
No abstract has been registered
Authors
Daniel Kwaku Addo Asante Igor A. Yakovlev Carl Gunnar Fossdal Gerrit Frantz Timmerhaus Jouni Partanen Øystein JohnsenAbstract
No abstract has been registered
Authors
Nina JohansenAbstract
Continuous light is a promising method to reduce the problems with rose powderymildew in greenhouse rose production. The effects of such a light regime on the performance of insect pests on roses have so far not been investigated. In the present study, survival, developmental time, and reproduction during one generation of the greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae), were characterized on roses, Rosa x hybrida cv. Passion, grown in climate chambers with long-day conditions (L20:D4) or continuous light (L24:D0) at 21 oC and fluctuating relative humidity (mean 74%, range 47–96%). Whiteflies reared under continuous light had lower immature survival and fecundity and shorter female longevity than whiteflies reared under long-day conditions, but immature developmental time was only slightly affected. Life-table analysis showed that the net reproductive rate (Ro) and intrinsic rate of natural increase (rm) were reduced by 85 and 76%, respectively, and the time for the population to double its size (D) was 4.2 times longer under continuous light. Thismean that the whitefly population growth under continuous light was strongly reduced compared with the traditional light regime used in rose production.
Abstract
No abstract has been registered
Authors
Hege Nordheim-Viken Harald VoldenAbstract
It is concluded that the ruminal aNDF degradation characteristics are affected by maturity Stage, and interactions with climatic factors such as temperature and water availability probably interact with maturity stage. Precautions should he made when prediction feed degradation characteristics from multiple regression analyses. (C) 2008 Published by Elsevier B.V.
Authors
Steffen Adler Annette Veberg Dahl Håvard Steinshamn Anne Holter Vae Erling Thuen Torstein H. Garmo Søren Krogh-JensenAbstract
A continuous grazing experiment with three measurement periods, 3 weeks each, was conducted with 16 Norwegian Red dairy cows in mid lactation to compare milk quality when grazing red clover-grass (R) or botanical diverse pasture (D). The cows were offered either R or D from the start of grazing season in mid May until beginning of September 2008. Milk yield was measured and milk samples were collected in the last week in each period (end of June, beginning of August and end of August). Pasture type had no effect on milk yield and milk content of fat or protein. Cows grazing R had higher proportion of the fatty acids C18:0 (22.41 vs. 9.96, P<0.05) and C18:1t11 (0.58 vs. 0.44 g/100g FAME, P<0.05) and lower proportion of C16:0 (27.83 vs. 30.92, P<0.05) in their milk fat than the cows grazing D. The milk content of ?-tocopherol was higher in milk from R than D (3.01 vs. 2.64 µg/ml, P<0.05). The oxidative stability of the milk lipids were only minor affected by pasture type.