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.
2008
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In Norway, public procurement of food to youth is not well developed in comparison to many other European and Scandinavian countries. School meals are only offered in very few primary schools, and the common school meal is a packed lunch (sandwiches) brought from home, consumed in the class room. Subscription schemes for milk were introduced around 1970, and for fruit around 1995. Organic milk and fruit is offered only in some regions. Since 2007, fruit is served without payment in all schools with a lower secondary level (class 8-10 or 1-10). This effort was introduced as a first step to develop a free school meal in all public schools, which is a goal of one of the political parties in the current government. As in many other European countries, free school meals were offered (especially to poor children) in schools in the larger Norwegian cities around 1900. However, these meals were criticised for being unhealthy, and replaced by whole grain bread, milk and vegetables around 1930. Increasing private wealth, and increased demand for investments in school buildings, books etc changed the public priority and free school meals disappeared in Oslo around 1960. Today, there is not a general agreement about the optimal school meal composition, and whether or not the meals should be funded by the public. However, the increasing length of the school day and unsatisfactory scores of Norwegian pupils in international comparison tests (e.g. PISA) makes the school meal sector highly relevant in the public debate. Three cases that will be studied in a research project about public organic food procurement for youth are briefly described: The municipality of Trondheim, Øya music festival in Oslo and the Air Force Academy. (Increased) serving of organic food is an important aim in all these cases, and young people are an important target group. The report is produced within the project “innovative Public Organic food Procurement for Youth”, iPOPY, and will be updated and revised during the project period (2007-2010).
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Quota regulations that prevent output expansion of farms and reallocation of output between farms can cause lower growth in output and productivity. The aim of this study was to explain the output growth rate of Norwegian dairy farms since 1976, and to decompose it into output, input, socioeconomic and technical change components. Instead of using the standard distance function approach for multi-output technologies, we use a growth rate formulation, which automatically removes the farm-specific effects. This formulation also helps to impose non-negativity constraints on marginal products of inputs (input elasticities), which are often violated for many observations, especially when flexible functional forms are used. The farm-level panel data cover three periods: before the quota scheme was introduced (1976-1982); the period with the most output-restricting quota scheme (1983-1996); and the period with a more flexible quota scheme (from 1997 onwards). Results show that the milk quota regulations had a significant constraining effect on output growth, in particular on milk output in the period 1983-1996. Furthermore, the output mix has shifted towards meat production for the average farm. What emerges from this study is that output growth and technical change are negatively influenced by policy aims where productive performance has not been the primary objective, and that there is scope for increased farm growth if the quota regime is liberalised.
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No abstract has been registered
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Environmental control of the annual growth cycle of 'Glen Ample' raspberry has been studied in order to facilitate crop manipulation for out-of-season production. Plants propagated from root buds were raised in long days (LD) at 21 degrees C and then exposed to different temperature and daylength conditions at varying ages. Shoot growth was monitored by weekly measurements and floral initiation by regular sampling and examination of axillary bud #5. Under natural summer daylight conditions at 60 degrees N shoot growth was nearly doubled at 21 degrees C compared with 15 degrees C, while at 9 degrees C one half of the plants ceased growing and formed flower buds at midsummer. Developing shoots have a juvenile phase and could not be induced to flower before the 15-leaf stage. No significant reduction in induction requirements was found in larger plants. Plants exposed to natural light conditions from 10th August, had an immediate growth suppression at 9 and 12 degrees C with complete cessation after 4 weeks (by September 7). This coincided with the first appearance of floral primordia. At 15 degrees C both growth cessation and floral initiation occurred 2 weeks later (by September 21), while at 18 degrees C continuous growth with no floral initiation was maintained until early November when the photoperiod had fallen below 9 h. The critical photoperiod for growth cessation and floral initiation at 15 degrees C was 15 h. Plants exposed to 10-h photoperiods at 9 degrees C for 2-4 weeks had a transient growth suppression followed by resumed growth under subsequent high temperature and LD conditions, while exposure for 5 or 6 weeks resulted in complete growth cessation and dormancy induction. The critical induction period for floral initiation was 3 weeks although no transitional changes were visible in the bud before week 4. When exposed to inductive conditions for marginal periods of 3 or 4 weeks, an increasing proportion of the plants (20% and 67%, respectively), behaved as primocane flowering cultivars with recurrent growth and terminal flowering. It is concluded that growth cessation and floral initiation in raspberry are jointly controlled by low temperature and short day conditions and coincide in time as parallel outputs from the same internal induction mechanism. (C) 2008 Elsevier B.V. All rights reserved.
Abstract
A field fertilizer trial planted in late August was used to study effects of fertilizer timing and application method on flowering and ripening in strawberry cv. Korona. In treatment 1 (T1), fertilization in August prior to planting was followed by fertigation with low nutrient rate from May to August in the first harvest year. In treatment 2 (T2) all nutrients were applied as nutrient solution from May to August the first harvest year. By August in the first harvest year, the total amount of fertilizer applied was similar for both treatments (80 kg N ha(-1)). Equal amounts of water were also applied in both treatments. In the second harvest year, all the fertilizer was applied using fertigation from May to August. Both treatments were given the same fertilizer rate (80 kg N ha(-1)) to study after-effects of T1 and T2. In the first harvest year, preplant fertilized plants flowered earlier and required a higher number of days and day-degrees from anthesis to berry ripening than did T2 plants which were not fertilized until spring the first harvest year. Significant differences were found in yield but not in the number of berries, as berry size was significantly higher in T1. No significant differences were found between fertilizer treatments in the second harvest year, although T2 tended to yield the maximum number of berries later in the season than T1.
Abstract
The environmental control of flowering in five populations of Fragaria virginiana ssp. glauca and three populations of F virginiana ssp. virginiana (henceforth referred to as F virginiana), obtained as seed from the National Plant Germplasm Repository, Corvallis, OR, USA, has been studied under controlled environment conditions. Except for the F virginiana ssp. glauca population PI 551648 from the Wasatch Mountains in Utah, which was truly day-neutral across a 9 degrees - 27 degrees C temperature range, all the other populations of both sub-species behaved as quantitative (facultative) short-day (SD) plants with earlier and more abundant flowering under SD than under long-day (LD) conditions. Flowering of the remaining F virginiana ssp. glauca populations was governed by a significant interaction of photoperiod and temperature. The SD dependence for flowering increased with increasing temperature from 9 degrees C to 27 degrees C. The optimum temperature for the SD flowering response was 15 degrees - 21 degrees C. While SD promotion of flowering was more pronounced in the F virginiana populations, temperature had no significant main effect on flowering in this sub-species, demonstrating a wide temperature tolerance for flowering. Vigorous runner formation was observed in all populations, in both SD and LD, with a highly significant advancement effect of increasing temperature. The flowering and runnering responses of these E virginiana populations are discussed in relation to their putative paternity of perpetual-flowering F. X ananassa cultivars. It is concluded that, with the complex inheritance in these octoploid plants, the flowering responses of the populations studied here are not reflected in the LD flowering response of cultivated everbearing strawberries.
Abstract
The environmental control of flowering in the perpetual-flowering (everbearing) diploid strawberry Fragaria vesca ssp. semperflorens cultivars 'Rugen' and 'Baron Solemacher' has been studied in controlled environments. Seed-propagated plants were exposed to 10-h short-day (SD) and 24-h long-day (LD) conditions at temperatures ranging from 9 degrees - 27 degrees C. The results revealed a quantitative LD response of flowering that increased in strength with increasing temperature, to become almost obligatory at 27 degrees C. Occasional runner formation was observed in SD at high temperature, conditions which were inhibitory to flowering, demonstrating that runnering ability is not completely lost in these genotypes. A comparison with the perpetual-flowering octoploid F X ananassa 'Elan', in one experiment, demonstrated an identical LD X temperature interaction in the two species. The results are discussed in relation to available information on the genetics of flowering habits in the two species. Since seasonal flowering types of F vesca and E X ananassa have also been shown to share a principally identical flowering response, controlled by SD and low temperature, it is concluded that a remarkably similar flowering control system is present in the diploid F vesca and the octoploid F. X ananassa. Despite the large genetic differences between the two species, and regardless of the origin of the cultivars, the seasonal flowering types are all SD plants, while their perpetual-flowering counterparts all appear to be LD plants. In both cases, there is a pronounced interaction with temperature; the photoperiodic responses increasing with increasing temperature, in both cases. This raises the question whether a common genetic flowering control system is present in both species.
Abstract
The effect of night temperature on short day (SD) floral induction has been studied in three June-bearing strawberry cultivars of different geographic origin and compared with yield performance in the cool Nordic environment. At the optimum day temperature of 18 degrees C, the SD flowering response of the cultivars 'Florence' and 'Korona' increased significantly with increasing night temperature from 9 to 18 degrees C, while an optimum was reached at 15 degrees C in the cultivar 'Frida' that is selected under cool-environment conditions in Norway. Also, while saturated flowering response was obtained with 3 weeks of SD treatment at all temperatures in 'Frida', several plants of 'Florence' and 'Korona' failed to initiate flowers at 9 degrees C night temperature even with 5 weeks of SD. The effect of extended SD period was particularly pronounced in 'Florence'. The slow SD floral induction response of 'Florence' was associated with a 2 week delay of anthesis in subsequent long day (LD) conditions at 21 degrees C. Yield performance of the same cultivars during 2 years under field conditions at Nes Hedmark and in North Norway also demonstrated that the yield potential of 'Florence' was not realized under the climatic conditions prevailing at these locations. In both years the yields varied significantly among the cultivars,'Frida' having the highest yields followed by 'Korona', with 'Florence' far below. It is concluded that, in the Nordic environment, autumn (September) night temperatures are obviously suboptimal for yield performance of some June-bearing strawberry cultivars, and that this effect is mediated by autumn temperature effects on flower initiation responses. (C) 2008 Elsevier B.V. All rights reserved.