| 1. |
- Albertsson, Ingrid, et al.
(författare)
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Functional interactions between nitrite reductase and nitric oxide reductase from Paracoccus denitrificans
- 2019
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Denitrification is a microbial pathway that constitutes an important part of the nitrogen cycle on earth. Denitrifying organisms use nitrate as a terminal electron acceptor and reduce it stepwise to nitrogen gas, a process that produces the toxic nitric oxide (NO) molecule as an intermediate. In this work, we have investigated the possible functional interaction between the enzyme that produces NO; the cd(1) nitrite reductase (cd(1)NiR) and the enzyme that reduces NO; the c-type nitric oxide reductase (cNOR), from the model soil bacterium P. denitrificans. Such an interaction was observed previously between purified components from P. aeruginosa and could help channeling the NO (directly from the site of formation to the side of reduction), in order to protect the cell from this toxic intermediate. We find that electron donation to cNOR is inhibited in the presence of cd(1)NiR, presumably because cd(1)NiR binds cNOR at the same location as the electron donor. We further find that the presence of cNOR influences the dimerization of cd(1)NiR. Overall, although we find no evidence for a high-affinity, constant interaction between the two enzymes, our data supports transient interactions between cd(1)NiR and cNOR that influence enzymatic properties of cNOR and oligomerization properties of cd(1)NiR. We speculate that this could be of particular importance in vivo during metabolic switches between aerobic and denitrifying conditions.
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| 2. |
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| 3. |
- Albertsson, Johannes, et al.
(författare)
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Effects of competition between short-rotation willow and weeds on performance of different clones and associated weed flora during the first harvest cycle
- 2014
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 70, s. 364-372
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Tidskriftsartikel (refereegranskat)abstract
- In order to assess the ability of willow clones to compete with weeds, willow shoot biomass and plant mortality were measured over the first harvest cycle for 10 commercial and two breeding clones at three different sites in southern Sweden. Two levels of weed pressure (weeded and not weeded) were employed and the effects of cutback or not after the first growing season were compared for willow clones under weed pressure. There were significant differences between clones in their ability to compete with weeds, measured as willow shoot growth reduction in plots with weeds, at two of the three sites. However, shoot biomass reduction due to weeds was large in all the clones, with Stina and SW Inger among the least affected. Mean shoot growth reduction after the first harvest cycle for the commercial clones was 68.3%, 91.2% and 94.3% at the three sites and the corresponding plant mortality was 9.8%, 57.3% and 56.2% under weed pressure. Significant clonal differences in yield, under weed-free conditions, were found at all three sites. Significant clonesite interactions were found for both growth reduction and biomass production. Cutting back shoots after the establishment season, under weed pressure, resulted in higher mean plant mortality and lower mean willow shoot biomass after one harvest cycle at two of the three sites. The weed flora was initially dominated by annuals, but became dominated by perennial weeds during the first harvest cycle. (C) 2014 Elsevier Ltd. All rights reserved.
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| 4. |
- Albertsson, Johannes, et al.
(författare)
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Effects of mechanical weed control or cover crop on the growth and economic viability of two short-rotation willow cultivars
- 2016
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 91, s. 296-305
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Tidskriftsartikel (refereegranskat)abstract
- Willow grown as short rotation coppice (SRC) is sensitive to weed competition, so herbicide treatment combined with mechanical weed control is recommended when establishing a plantation. This study compares that practice with two mechanical, row crop cultivator (RC) and row crop cultivator with torsion weeder (RCT), and two cultural treatments, cover crop (CC) and cut cover crop (CCC), to control weeds. Willow responses to these treatments were compared during the first three years after planting using two cultivars, Gudrun and Tordis with broad and narrow leaves, respectively. At harvest, the RCT treatment had produced 27% more biomass than the RC treatment (13.9 vs 11.0 Mg ha(-1) dry matter) and approximately three times more than the cultural treatments. However, the standard control treatment, herbicides and row crop cultivator (HRC), produced more than all other treatments (17.3 Mg ha(-1) dry matter). The two cultural treatments had higher plant mortality (CC 26.2% and CCC 32.8%) than the other treatments (HRC 2.7%, RC 7.0% and RCT 7.0%) after the first harvest cycle. No interaction between cultivar and treatment was found for willow shoot biomass, weed biomass or plant mortality. Overall, however, Gudrun had lower plant mortality and less weed biomass after the first harvest cycle than Tordis. All treatment and cultivar combinations gave positive financial annual returns when the whole life-span of the plantation was considered. This study suggests that without using herbicides, it is possible to establish a willow SRC plantation that produce enough to be economically viable. (C) 2016 Elsevier Ltd. All rights reserved.
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| 5. |
- Albertsson, Johannes
(författare)
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Impact and control of weeds in biomass willow clones
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Willow (Salix spp.) grown on arable land as short-rotation coppice (SRC) produces renewable energy in the form of woody biomass. This perennial crop has a high ratio of energy output to input and a good environmental profile. However, weed control is mostly dependent on herbicide use. Therefore, this thesis examined the possibility to further improve the environmental profile of willow SRC by omitting the use of herbicides during establishment. If genetic variation in willow competitiveness to weeds exists, more weed-competitive cultivars might be bred. However, in a study performed at three different sites in southern Sweden, only small differences were found between 12 clones tested for their ability to compete with weeds. Depending on site, weeds reduced stem biomass yield by between 68 and 94% after the first harvest cycle and increased plant mortality at all sites. The practice of cutting the first-year shoots either reduced or did not affect the ability of the willow plants to compete with weeds. Hence, this measure should be omitted provided this is compatible with other management actions. A study on the efficiency and economic returns from four different non-chemical weed control methods during willow establishment of two different cultivars showed that it is possible to establish an agriculturally and economically viable willow plantation without the use of herbicides. The most promising non-chemical weed control method involved repeated passes with a row crop cultivator equipped with torsion weeders, while the least promising method was a living clover cover crop. Yield data were obtained from the weed competition study for the willow SRC clones when subjected to thorough weeding. Cultivars Sven and Tordis were found to be among the highest yielding at all three sites, although site x clone interactions were found. However, these two clones did not yield significantly more than two more recently bred clones, Klara and Linnea, at any site. Biomass estimates from destructive and non-destructive methods have been shown to differ and the magnitude of these differences may depend on clone. A study with six different clones showed that assumptions regarding harvest height and dry matter content of clones might explain part of these differences.
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| 6. |
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| 7. |
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| 8. |
- Albertsson, Johannes, et al.
(författare)
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Site-related set-back by weeds on the establishment of 12 biomass willow clones
- 2014
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 54, s. 398-407
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Tidskriftsartikel (refereegranskat)abstract
- Ten commercial clones of willow and two breeding clones were studied for their ability to compete with weeds during the establishment year at three different sites in southern Sweden. Cuttings were planted according to commercial practice in April, and the two treatments, 'Weeded' and 'Unweeded', were laid out in a strip-plot design. Weeds in the 'Weeded' treatment were removed mechanically and by hand hoeing. Willow plant shoot weight and plant mortality were measured after the first growing season to evaluate the initial effect of weeds. In addition, weed flora, weed aboveground biomass, soil properties, shoot damage and soil moisture were assessed during the growing season. Plant mortality was <1% in the 'Weeded' treatment at the three study sites, while in 'Unweeded' it was significantly higher, 2.7%, 24.6% and 37.4%. Weeds reduced willow plant shoot weight by 93.4%, 94.0% and 96.1% at the three sites. Only one site showed clonal differences in shoot growth reduction, as well as in plant mortality. These results show the importance of weed control in willow plantations, as growth of all clones tested were dramatically hampered by weeds during the first growing season, regardless of trial site conditions. Moreover, conditions at certain sites, such as soil properties in combination with weed cover, may cause high plant mortality during the establishment year in this perennial biomass crop.
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| 9. |
- Albertsson, Johannes, et al.
(författare)
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Subsoiling starch potato
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Soil compaction due to heavy machinery and intensive cultivation causing yield reduction in potato is an increasing problem worldwide today. In this experiment inter-row subsoiling at the depth of 55 cm has been tested as a strategy to loosen the soil after planting and thereby increase the yield in starch potato production. The effects of subsoiling were tested in three different irrigation regimes. The results show that subsoiling can increase the starch potato yield significantly in sandy soils where a compacted plough pan is present. This holds true for all years and all cultivars tested. The effect was greater in dry years and decreased with increasing irrigation intensity. However, the starch content of the tubers was not affected by subsoiling but the total starch yield from the field increased with 0.86 ton/ha to 1.37 ton/ha, depending on year, cultivar and irrigation strategy.
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| 10. |
- Albertsson, Johannes, et al.
(författare)
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Subsoiling starch potato : Higher yields of starch potatoes and improved water management
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Soil compaction due to heavy machinery and intensive cultivation causing yield reduction in potato is an increasing problem worldwide today. In this experiment inter-row subsoiling at the depth of 55 cm has been tested as a strategy to loosen the soil after planting and thereby increase the yield in starch potato production. The effects of subsoiling were tested in three different irrigation regimes. The results show that subsoiling can increase the starch potato yield significantly in sandy soils where a compacted plough pan is present. This holds true for all years and all cultivars tested. The effect was greater in dry years and decreased with increasing irrigation intensity. However, the starch content of the tubers was not affected by subsoiling but the total starch yield from the field increased with 0.86 ton/ha to 1.37 ton/ha, depending on year, cultivar and irrigation strategy
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