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.
2016
Abstract
No abstract has been registered
Authors
Lars T. HavstadAbstract
No abstract has been registered
Authors
Lars T. HavstadAbstract
The market for herbage seed straw has diminished in many seed-production areas due to less livestock. Seed growers are therefore looking for alternatives to straw removal, which up to now has been the most common practice. During 2000–2006, different alternative straw chopping methods, both at the back of the combiner and with a tractor-mounted flail-chopper, and field burning strategies were evaluated in seed crops of timothy (Phleum pratense) and meadow fescue (Festuca pratensis) in southeast Norway. The requirement for an extra N input in autumn (30–40 kg ha-1) when practising straw chopping was also examined. Compared to straw removal, straw chopping at the back of the combiner during seed harvest did not reduce seed yield in the following year as long as stubble height was low (<10 cm in timothy) and the straw spread uniformly in the field. On average, seed yield was 1–4% and 1–9% higher compared to straw removal in timothy and meadow fescue, respectively. If the chopped straw was spread unevenly, or long stubble was left at combining, it is recommended to use a tractor-mounted flail-chopper after harvest. The experiments did not provide any support for an extra input of nitrogen in autumn, either in timothy or meadow fescue, when the straw was chopped rather than removed. Burning of stubble and straw soon after seed harvest was another efficient clean-up method after harvest, which increased seed yield 9–15% and 17–20% compared to straw removal in the two species, respectively. However, as the burning method is risky and causes smoke emissions, it is normally not recommended. It is concluded that for most seed growers, the most effective, least laborious and most environment-friendly alternative to straw removal will be to chop the straw at the back of the combiner during seed harvest.
Abstract
No abstract has been registered
Abstract
The effects of soil variability on regional crop yield under projected climate change are largely unknown. In Southeastern Norway, increased temperature and precipitation are projected for the mid-21st century. Crop simulation models in combination with scaling techniques can be used to determine the regional pattern of crop yield. In the present paper, the CSM-CROPSIM-CERES-Wheat model was applied to simulate regional spring wheat yield for Akershus and Østfold counties in Southeastern Norway. Prior to the simulations, parameters in the CSM-CROPSIM-CERES-Wheat model were calibrated for the spring wheat cvars Zebra, Demonstrant and Bjarne, using cultivar trial data from Southeastern Norway and site-specific weather and soil information.Weather input data for regional yield simulations represented the climate in 1961–1990 and projections of the climate in 2046–2065. The latter were based on four Global Climate Models and greenhouse gas emission scenario A1B in the IPCC 4th Assessment Report. Data on regional soil particle size distribution, water-holding characteristics and organic matter data were obtained from a database. To determine the simulated grain yield sensitivity to soil input, the number of soil profiles used to describe the soilscape in the region varied from 76 to 16, 5 and 1. The soils in the different descriptions were selected by arranging them into groups according to similarities in physical characteristics and taking the soil in each group occupying the largest area in the region to represent other soils in that group. The simulated grain yields were higher under all four projected future climate scenarios than the corresponding average yields in the baseline conditions. On average across the region, there were mostly non-significant differences in grain yield between the soil extrapolations for all cultivars and climate projections. However, for sub-regions grain yield varied by up to 20% between soil extrapolations. These results indicate how projected climate change could affect spring wheat yield given the assumed simulated conditions for a region with similar climate and soil conditions to many other cereal production regions in Northern Europe. The results also provide useful information about how soil input data could be handled in regional crop yield determinations under these conditions.
Abstract
Black currant is a woody plant in which growth and development are intimately controlled by, and synchronised with seasonal changes in photoperiod and temperature. Concern over the potential impact of global warming on plant phenology and yield, led us to initiate relations. An experimental system with single-stemmed potted plants was developed which allowed a research program to address both qualitative and quantitative assessment of climatic responses. Growth cessation and flowering were both induced by short days, with critical photoperiods of approximately 17 and 16 h, respectively, for most cultivars. Both processes were advanced and promoted by increasing autumn temperature with an optimum in the 18-21°C region. An exception was cultivars of high-boreal origin, which had an early growth cessation at low temperature. Unexpectedly, however, not all plants flowered after exposure to 10 h photoperiod, and the number of flowers decreased as the photoperiod was reduced from the near-critical length of 15 h. This was due to premature dormancy induced by an abrupt change to photoperiods well below the critical level. Field experiments revealed that cultivars of varying geographic origin, exhibited a typical latitudinal cline in their photoperiodically controlled timing of growth and flowering responses. Breaking of bud dormancy and promotion of flower bud development required chilling at -5°C for 14 weeks or more for optimal responses. However, while chilling at -10°C for 8 weeks resulted in dormancy release, continued chilling to 16 weeks inhibited bud break completely. We therefore propose that excessive chilling induces secondary bud dormancy in black currant. The observed high chilling requirements of black currants concur with the reported vulnerability of this crop to declining winter chill in the wake of the ongoing global warming. Furthermore, such conditions also induce a particularly deep bud dormancy state that further increases the chilling need.
Abstract
No abstract has been registered
Abstract
In order to investigate the relationship between environmental conditions and vegetative growth and reproductive development in the strawberry, freshly rooted runner plants of the cultivar ‘Sonata’ were grown in a phytotron at temperatures of 12, 18 and 24 °C and photoperiods of 10 h short day (SD) and 20 h long day (LD) for 31 d and harvested at 10 d intervals. Plant dry weight and leaf area increases were exponential versus time, giving a linear regression with the natural log (ln). This rendered the relative growth rate (RGR) constant over time at each environmental condition. Over the entire 31 d growth period, the RGR increased linearly with increasing temperature across the range of temperatures with a further 10–13% enhancement by LD. A maximum RGR value of 0.077 g/g/d was determined in LD at 24 °C. Increases in the RGR was driven by a combined increase in net assimilation rate (NAR) and leaf area ratio (LAR) and was associated with an increased allocation of dry matter production into leaves and less into crowns and roots. Because of this, the shoot/root ratio increased consistently with increasing temperature and photoperiod, which was also associated with a significant increase in the tissue C/N concentration ratio. Low temperature promoted starch accumulation markedly in all parts of the plants, with a further enhancement by LD conditions, while the concentrations of soluble sugars were less affected by the climatic environment. Forcing of plants exposed to the various growth conditions for 31 d showed that all plants at 12 and 18 °C and 80% of those at 24 °C had initiated flowers in SD, whereas none had initiated flowers in LD regardless of temperature conditions. All these results demonstrate an opposite environmental relationship between vegetative growth and reproductive development in the strawberry.
Abstract
As part of an overall assessment of the commercial suitability of strawberry cultivars for the Nordic environment, we studied 13 diverse cultivars in an experimental field in South East Norway. Early-maturing cultivars were characterized by early initiation of floral primordia and early flowering and fruit maturation. High temperatures in July and early August delayed floral initiation in the early cultivars, resulting in more synchronous initiation of early and late cultivars. The recent Norwegian cultivar ‘Nobel’, which has an everbearing parent, differed from the other cultivars by early initiation also at elevated summer temperature. Inadequate yield and berry size were identified as important causes for outdating of older cultivars, such as ‘Senga Sengana’ and ‘Glima’. Overall, the high-yielding and large-fruited ‘Sonata’ was judged as the best fresh consumption cultivar in Norway, and market trends indicate that it will continue to expand its market share at the expense of ‘Korona’, mainly because of inadequate fruit firmness and shelf life of the latter. Adequate yields and berry quality justify the use of the late maturing ‘Florence’ for prolongation of the fresh market season. The results are discussed together with practical experiences and market preferences in an attempt to provide overall cultivar recommendations for Norway.
Authors
Elli Aurora Koskela Anita Sønsteby Henryk Flachowsky Ola M. Heide Magda-Viola Hanke Paula Elomaa Timo HytönenAbstract
The effects of daylength and temperature on flowering of the cultivated octoploid strawberry (Fragaria × ananassa Duch.) have been studied extensively at the physiological level, but information on the molecular pathways controlling flowering in the species is scarce. The flowering pathway has been studied at the molecular level in the diploid short-day woodland strawberry (F. vesca L.), in which the FLOWERING LOCUS T1 (FvFT1)–SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (FvSOC1)–TERMINAL FLOWER1 (FvTFL1) pathway is essential for the correct timing of flowering. In this work, we show by transgenic approach that the silencing of the floral repressor FaTFL1 in the octoploid short-day cultivar ‘Elsanta’ is sufficient to induce perpetual flowering under long days without direct changes in vegetative reproduction. We also demonstrate that although the genes FaFT1 and FaSOC1 show similar expression patterns in different cultivars, the regulation of FaTFL1 varies widely from cultivar to cultivar and is correlated with floral induction, indicating that the transcription of FaTFL1 occurs at least partially independently of the FaFT1–FaSOC1 module. Our results indicate that changing the expression patterns of FaTFL1 through biotechnological or conventional breeding approaches could result in strawberries with specific flowering and runnering characteristics including new types of everbearing cultivars.