| 1. |
- Abreha, Kibrom Berhe, et al.
(författare)
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Late Blight Resistance Screening of Major Wild Swedish Solanum Species: S. dulcamara, S. nigrum, and S. physalifolium
- 2018
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Ingår i: Phytopathology. - 0031-949X .- 1943-7684. ; 108, s. 847-857
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Tidskriftsartikel (refereegranskat)abstract
- To understand the contribution of wild Solanum species to the epidemiology of potato late blight in Sweden, we characterized the resistance of the three putative alternative hosts: S. physalifolium, S. nigrum, and S. dulcamara to Phytophthora infestans, the causal agent of late blight. The pathogen sporulated in all 10 investigated S. physalifolium genotypes, suggesting susceptibility (S phenotype). Field-grown S. physalifolium was naturally infected but could regrow, though highly infected genotypes were smaller at the end of the season. In 75 S. nigrum genotypes, there were no symptoms (R phenotype) or a lesion restricted to the point of inoculation (RN phenotype), indicating resistance. In 164 S. dulcamara genotypes, most resistance variability was found within sibling groups. In addition to the three resistance phenotypes (R, RN, and S), in S. dulcamara a fourth new resistance phenotype (SL) was identified with lesions larger than the point of inoculation but without visible sporulation of the pathogen. Quantitative PCR confirmed P. infestans growth difference in RN, SL, and S phenotypes. Thus, in Sweden S. physalifolium is susceptible and could be a player in epidemiology. A limited role of S. dulcamara leaves in the epidemiology of late blight was suggested, since no major symptoms have been found in the field.
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| 2. |
- Henriksson, Natalie D., et al.
(författare)
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Topsoil removal enhances plant target species occurrence in sandy calcareous grassland
- 2019
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Ingår i: Flora: Morphology, Distribution, Functional Ecology of Plants. - : Elsevier BV. - 0367-2530. ; 256, s. 7-15
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Tidskriftsartikel (refereegranskat)abstract
- Species-rich sandy calcareous grasslands are threatened by land use change, eutrophication and acidification. Disturbance is vital for the persistence of characteristic sandy calcareous grassland species because it provides habitats with low competition, and can lead to increased pH and decreased nutrient availability, which favour many threatened species. Today many sandy calcareous grasslands lack a proper disturbance regime. The outcome of topsoil removal, applied as restoration measure, was investigated in a multi-site study. Successful restoration was associated with colonisation of plants representing conservation target species, as well as increased pH and reduced amounts of nutrients and organic matter. The impact of topsoil removal on plant species composition and soil properties was examined, with adjacent degraded plots serving as controls. Non-degraded target vegetation was included as reference areas. Restored plots had a significantly higher mean proportion of target species compared to control plots. However, control plots had higher species richness. Topsoil removal increased the pH value and decreased contents of ammonium and organic matter in the newly established topsoil layer, while no effect was seen on nitrate, phosphate and lime. Restored plots had a high cover of bare sand, but in contrast to target plots, a rather low proportion of forbs in relation to graminoids. Control plots had a higher vegetation cover, mainly represented by graminoids, forbs and the dwarf shrub species Calluna vulgaris (L.) Hull. Our study suggests that topsoil removal is an effective restoration measure due to its positive influence on soil characteristics and target species. However, the degraded sandy grasslands that were chosen as controls in this study should also be recognised as important habitats with conservation values due to the high species richness, suggesting that a mosaic pattern of the different successional stages is desirable.
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| 3. |
- Hydbom, Sofia, et al.
(författare)
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Biochemical signatures reveal positive effects of conservation tillage on arbuscular mycorrhizal fungi but not on saprotrophic fungi and bacteria
- 2021
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393. ; 157
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Tidskriftsartikel (refereegranskat)abstract
- Since tillage can reduce the amount of organic C stored in soils, the use of conservation tillage practices, which exclude soil inversion, or include it less frequently, is often promoted. Soil microorganisms are closely linked to soil organic C (SOC), and they are assumed to respond quicker to management changes than SOC. Using two Swedish long-term tillage experiments, our aim was to determine whether (i) continuous conservation tillage (harrowing, H) increase microbial biomass (indicated by fatty acid signatures) compared to plowing (P), and if occasionally tilled soil (HP) was more like H or P. Also, the aim was to determine whether (ii) crop residue management has different effects on microbial biomass depending on tillage management, and whether (iii) conservation tillage and residue return increase SOC. We found that arbuscular mycorrhizal fungi (AMF) were stimulated by the H treatment compared to P treatment in the upper soil layer, and that occasional plowing resulted in intermediate amounts of AMF. The amount of microbial saprotrophs, on the other hand, was not affected by tillage treatment, and neither was the SOC concentration. Whether crop residues were returned in the autumn or not, had no direct effect on the microbial saprotrophs or the SOC after the winter, but crop residue removal stimulated AMF close to the surface in the P treatment. Although more research is needed to fully understand agricultural tillage and residue management effects on SOC dynamic, our study suggests that reducing or omitting plowing influence soil microbes, but does not necessarily result in more SOC.
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| 4. |
- Hydbom, Sofia, et al.
(författare)
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Reduced tillage stimulated symbiotic fungi and microbial saprotrophs, but did not lead to a shift in the saprotrophic microorganism community structure
- 2017
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 119, s. 104-114
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Tidskriftsartikel (refereegranskat)abstract
- The need for sustainable agricultural systems, which for example enhance soil organic carbon (SOC) content, has increased the interest for management with reduced tillage. In this study we used a Swedish long-term (20 yrs.) systems experiment, including reduced tillage (harrowing 10 cm) and plowing (moldboard plow 0–20 cm) combined with three levels of nitrogen (N) fertilization. With this setup we tested if (1) the arbuscular mycorrhizal fungi (AMF) concentration and (2) the fungi to bacteria (F:B) ratio would be higher under reduced tillage than under conventional tillage, and if this would be associated with higher SOC concentrations. We also tested if (3) the microbial biomass C close to the surface would be higher under reduced tillage than conventional tillage. Furthermore, since disturbance can reduce respiration and microbial growth we tested if (4) this occurred in our reduced tillage system. In addition, we tested if (5) fertilization increased the growth rate of fungi and decreased that of bacteria. We collected soil samples in July and October and found that the microbial biomass C, measured in October only, was higher close to the surface in the reduced tillage treatment and so was the microbial respiration. The fungal and bacterial growth rate, on the other hand, were not affected by tillage treatment. Fertilization did not affect the bacterial growth rate but did have a positive effect on fungal growth rate. In accordance with our expectations reduced tillage had a stimulating effect on AMF and saprotrophic fungi, and contrary to our expectation, also bacteria were positively affected by reduced tillage. In line with the unchanged F:B ratio, we found no indication that even 20 years of reduced tillage increased SOC concentrations in the long term.
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| 5. |
- Hydbom, Sofia, et al.
(författare)
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The effects of pH and disturbance on the bryophyte flora in calcareous sandy grasslands
- 2012
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Ingår i: Nordic Journal of Botany. - : Wiley. - 0107-055X. ; 30:4, s. 446-452
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Tidskriftsartikel (refereegranskat)abstract
- The unique flora and fauna of calcareous sandy grasslands is threatened by acidification, eutrofication and changed land use. Restoration experiments in such grasslands in southern Sweden, including deep and shallow soil perturbation, allowed us to examine the effects of pH and disturbance on the bryophyte flora. We also studied natural pH and disturbance gradients in order to compare the natural pH and disturbance variation with the responses of experimental manipulation. We found that increased pH due to soil perturbation resulted in increased species richness. However, in naturally disturbed areas, pH seemed to have a lower effect, and instead, the location of the site and possibly the site history had a larger influence on species richness. We also found that some of the species that were common at naturally high pH (mainly acrocarps) were favoured by experimental pH manipulation. Our results pointed out Syntrichia ruraliformis as a sensitive pH indicator, being almost exclusively restricted to pH values above 7. The species can also serve as an indicator of sand steppe vegetation.
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| 6. |
- Hydbom, Sofia, et al.
(författare)
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The use of conservation tillage in an agro-intensive region : results from a survey of farmers in Scania, Sweden
- 2020
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Ingår i: Renewable Agriculture and Food Systems. - 1742-1705. ; 35:1, s. 59-68
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Tidskriftsartikel (refereegranskat)abstract
- Conventional agricultural practices can lead to soil erosion and a reduction in soil organic carbon (SOC) content. It has been suggested that less intensive agricultural practices, such as conservation tillage (including no-till and reduced till without soil inversion) may reduce both erosion and loss of SOC. The aim of this study was to determine whether, and why, conservation tillage is used in Scania, which is one of the most agro-intensive regions in Sweden. We also investigated how information on tillage practices is obtained, why one type of tillage may be favored over another, and whether some farmers are more likely to use conservation tillage. The result of this study will benefit policy makers and researchers by pinpointing factors that influence the use of conservation tillage. To collect data, a questionnaire was sent to farmers in Scania in 2016. We found that the majority of the responding farmers used conservation tillage, and that it was more likely to be used if the farmer was highly educated and spent more than 50% of their annual working time on crop production. The use of conservation tillage was also more common if the farm was large and clay soil dominated. Crop rotation was often highlighted as the most important factor influencing the choice of tillage practice, which may be due to crop species requirements. When asked to compare the consequences of reduced tillage and plowing, the perception of farmers using conservation tillage was in general more positive, indicating skepticism toward the practice of reduced tillage until it had been tried. We show that the use of conservation tillage, sometimes in combination with plowing, is widespread in Scania. However, unless changes in, for example, crop rotation and labor requirements occur, the use of conservation tillage will most likely remain the same as today, or only increase slightly in the near future. Farm enlargement may result in an increased conservation tillage use, and so may efforts to educate advisors, increased opportunities for peer-to-peer meetings, and the development of economically viable small farm solutions. Increased conservation tillage may be part of the solution for sustainable crop production, but drawbacks such as increased pesticide use must be addressed further, as well as factors such as crop rotation development and practical knowledge that influence conservation tillage use at the farm level.
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| 7. |
- Hydbom, Sofia
(författare)
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Tillage practices and their impact on soil organic carbon and the microbial community
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Soil microorganisms are important for climate regulation as well as for plant nutrition. In agricultural soils the microorganisms are affected by management choices, like which type of tillage that is used. Moldboard plowing, the most common tillage practice, increases mineralization which leads to soil organic carbon (SOC) loss, and may thus reduce soil quality. Conservation tillage practices infer less soil disturbance and they are considered to reduce mineralization compared to plowing, and favor fungi to greater extent than bacteria, which has been suggested to result in increased SOC content. Conservation tillage has been implemented by farmers worldwide to reduce soil erosion and also to improve farm economy. The main aims of this thesis were to find out how conservation tillage affect SOC concentrations and the soil microbial community compared to plowing, and which type of farmers that are likely to use conservation tillage and why. The effects of tillage practice on SOC, arbuscular mycorrhizal fungi (AMF), saprotrophic fungi and bacteria, were evaluated using three Swedish long-term tillage experiments, whereas a questionnaire was sent out to Scanian farmers to find out more about conservation tillage use. I found that long-term conservation tillage do not necessarily lead to an increase in SOC concentrations, and that fungi and particularly AMF benefit from reduced tillage. Although the tillage treatment effect on the microbial activity was not consistent, the respiration rate was often higher under conservation tillage than under plowing, at least when measured near the soil surface. Furthermore, a typical farmer who use conservation tillage is highly educated and work more than halftime with crop production. I also learned that crop rotation, labor savings and soil type are often considered when deciding on which tillage type to use. To conclude, use of conservation tillage may not increase SOC concentrations in the studied areas, but can still be attractive to farmers as it benefits AMF and can lead to better farm economy, if implemented on suitable soil and with an adapted crop rotation.
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| 8. |
- Lankinen, Åsa, et al.
(författare)
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Effects of soil resources on expression of a sexual conflict over timing of stigma receptivity in a mixed-mating plant
- 2017
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 126, s. 692-702
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Tidskriftsartikel (refereegranskat)abstract
- While environmental factors strongly influence plant growth and reproduction, less is known about environmental effects on sexual selection and sexual conflict. In this study on mixed-mating Collinsia heterophylla we investigated whether soil resource environment affected traits associated with sexual conflict. In C. heterophylla a sexual conflict over timing of stigma receptivity occurs. Early stigma receptivity benefits pollen parents by securing paternity while late stigma receptivity benefits female fitness in terms of increased seed production. We performed hand-pollinations combining recipients and donors grown either in high or low resource environments and asked whether these treatments influenced sexual conflict traits - recipient- and donor-based influence on timing of stigma receptivity - and conflict costs related to reduced early seed production. We also asked whether resource environment affected eight traits related to general fitness and mating system. Sexual conflict-associated traits - timing of stigma receptivity and seed production -were generally unaffected by resource environment. While no universal effect of resources was detected, we did observe donor-specific responses to environment, suggesting that environment can nonetheless contribute to variation in timing of stigma receptivity. Recipients grown under low resources showed pronounced differences among donors for number of seeds per capsule, indicating that recipients favour some donors over others under resource-low conditions. Moreover, high resources increased number of flowers but reduced pollen germination rate, while other traits were unaffected, indicating variation in the response to resource environment for fitness-and mating system-traits. Our results suggest that even though soil resource environment had a low impact on the sexual conflict traits and related costs in C. heterophylla, it generated variability in pollen donor-influence on this trait and in recipient sorting among donors. Thus, it is possible that both sexual conflict and sexual selection is affected by environmental factors not only in animals but also in plants.
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| 9. |
- Lankinen, Åsa, et al.
(författare)
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Sexually antagonistic evolution caused by male-male competition in the pistil
- 2017
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 71:10, s. 2359-2369
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Tidskriftsartikel (refereegranskat)abstract
- Although sexual selection and sexual conflict are important evolutionary forces in animals, their significance in plants is uncertain. In hermaphroditic organisms, such as many plants, sexual conflict may occur both between mating partners (interlocus conflict) and between male and female sex roles within an individual (intralocus conflict). We performed experimental evolution, involving lines that were crossed with either one or two pollen donors (monogamous or polyandrous lines), in the hermaphroditic plant (Collinsia heterophylla) where early fertilizations are associated with female fitness costs (reduced seed set). Artificial polyandry for four generations resulted in enhanced pollen performance and increased female fitness costs compared to the monogamous and source (starting material) lines. Female fitness was also reduced in the monogamous line, indicating a possible trade-off between sex roles, resulting from early pollination. We performed a second experiment to investigate a potential harming effect of pollen performance on seed set. We found that high siring success of early arriving pollen competing with later-arriving pollen was associated with high female fitness costs, consistent with an interlocus sexual conflict. Our study provides evidence for the importance of sexual selection in shaping evolution of plant reproductive strategies, but also pinpoints the complexity of sexual conflict in hermaphroditic species.
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| 10. |
- Madjidian, Josefin, et al.
(författare)
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Influence of number of pollinations and pollen load size on maternal fitness costs in Collinsia heterophylla: implications for existence of a sexual conflict over timing of stigma receptivity.
- 2012
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Ingår i: Journal of evolutionary biology. - : Wiley. - 1420-9101 .- 1010-061X. ; 25:8, s. 1623-1635
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Tidskriftsartikel (refereegranskat)abstract
- Costs related to pollen competition have rarely been considered, but are expected in the case of sexual conflict where male and female sexual functions have opposing evolutionary interests. In Collinsia heterophylla, delayed stigma receptivity is beneficial as it enhances pollen competition. A sexual conflict over timing of stigma receptivity has been proposed in this species as early pollination, following one-time pollinations, is advantageous to pollen donors at a cost of reduced maternal seed set (measured as seed number). In this study, we explored whether the maternal cost was still present following an additional pollination. We hypothesized that the cost is caused either by harm related to early pollen presence or by factors unrelated to harm. We performed pollinations at different stages of floral development, either one or two pollinations (24-h time lag), and varied the size of the first pollen load in the latter category. Early pollination reduced seed biomass also after two-time pollinations, suggesting a persistent maternal cost of early pollen presence. Further, pollen load size modified seed production, possibly indicating that dose-dependent harm influences the maternal cost of early fertilization. Our results strongly suggest negative effects of pollen competition on maternal fitness following early pollination, which is consistent with the existence of a sexual conflict over timing of stigma receptivity. In conclusion, we propose that much could be gained if more plant studies considered the potential for fitness costs in relation to sexual conflict, particularly those investigating pollen-pistil interactions.
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