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
This report gives a summary of results from the STERF-project FESCUE GREEN 2011-2015.
Abstract
No abstract has been registered
Abstract
Satisfactory seed yield of red clover (Trifolium pratense L.) cultivars is crucial for the availability of seeds on the market. Many breeders and researchers have used seed yield components to measure, compare, and explain differences in seed yield between diploid and tetraploid red clover cultivars and populations; however, the relative importance of each component varies between studies. In 2011 and 2012, single-plant trials with several tetraploid and one diploid red clover cultivar were established at the Norwegian plant breeding station at Bjørke. The goal was to study the impact of different seed-yield components on the seed yield of tetraploid plants. Seed weight per flower head was the seed-yield component that correlated best with the seed yield plant−1 (r = 0.91 and r = 0.68 in 2011 and 2012, respectively). Path coefficient analysis has also shown that the seed weight per flower head had the highest direct impact on seed yield plant−1 (direct path coefficients were 0.867 and 0.783 in 2011 and 2012, respectively). In comparison, the direct path coefficients for calculated number of flower heads, which was previously highlighted as the most important seed-yield component, were lower and more variable (0.739 and 0.392 in 2011 and 2012, respectively). Since previously seed yield per flower head was also identified as the most important seed-yield component in dense plant canopy, this component might have the potential to select for improved seed yield of new cultivars based on single plants. However, further studies are required to confirm this conclusion.
Authors
Helga Amdahl Trygve S. Aamlid Åshild Ergon Mallikarjuna Rao Kovi Petter Marum Muath K Alsheikh Odd Arne RognliAbstract
While tetraploid plants of red clover are taller, have thicker stems, and have broader leaves that altogether result in a higher forage yield compared to diploids, they generally have substantially lower seed yields than diploid plants. Tetraploid red clover can be induced chemically by colchicine or nitrous oxide (N2O) and sexually by union of unreduced gametes. The average seed yield of tetraploid red clover in Norway is 60% of the diploid yield, while in Sweden it is 75%. One objective of this paper was to examine whether there is a difference in seed yield among chromosome doubled tetraploids and crossed tetraploids. A second objective was to investigate differences in seed yield and seed yield components in Norwegian and Swedish tetraploid populations. The third objective was to study which yield component most correlates with the seed yield per hectare. Seed production experiments were established at Landvik and Bjørke in Norway and Svalöv and Lännäs in Sweden. Populations made by crossings of tetraploids gave significantly greater yield (p < 0.001) compared to populations that were made by chromosome doubling. On average, Norwegian and Swedish varieties had equal yields in both experimental years. Norwegian and Swedish varieties differed mostly in earliness traits. Swedish populations began flowering on average 4 d earlier than Norwegian populations. Genotypic correlations showed that seed yield per flower head was the component with the highest correlation (r = 0.956 and r = 0.977) with yield per hectare in both experimental fields. Results from the second experimental year indicate a trend towards improved seed yield after several cycles of recurrent selection for higher seed yield per flower head.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Effects of clear-cut harvesting on ground vegetation plant species diversity and their cover are investigated at two Norway spruce sites in southern Norway, differing in climate and topography. Experimental plots at these two sites were either harvested conventionally (stem-only harvesting) or whole trees including crowns, twigs and branches were removed (whole-tree harvesting), leaving residue piles on the ground for some months. We compare the number of plant species in different groups and their cover sums before and after harvesting, and between the different treatments, using non-parametric statistical tests. An overall loss of ground vegetation biodiversity is induced by harvesting and there is a shift in cover of dominant species, with negative effects for bryophytes and dwarf shrubs and an increase of graminoid cover. Differences between the two harvesting methods at both sites were mainly due to the residue piles assembled during whole-tree harvesting and the physical damage made during the harvesting of residues in these piles. The presence of the residue piles had a clear negative impact on both species numbers and cover. Pile residue harvesting on unfrozen and snow-free soil caused more damage to the forest floor in the steep terrain at the western site compared to the eastern site.
Abstract
No abstract has been registered
Authors
Tonje Økland Jørn-Frode Nordbakken Holger Lange Ingvald Røsberg O. Janne Kjønaas Kjersti Holt Hanssen Nicholas ClarkeAbstract
No abstract has been registered