| 1. |
- Jensen, Anna M
(författare)
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Effects of facilitation and competition on oak seedlings : using shrubs as nurse-plants to facilitate growth and reduce browsing from large herbivores
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Plant–plant interactions have been indicated as a potential means to facilitate oak seedling establishment and reduce herbivory when restoring oak forests. The aim of this thesis was to investigate mechanisms and outcomes of competitive and indirectly facilitative interactions between oak (Quercus robur and Q. petraea) seedlings and neighboring plants, primarily shrubs. The associational resistance of planted oak seedlings to larger herbivores provided by naturally occurring shrubs was tested in ten temperate broadleaved forests across southern Sweden. The results showed that shrubs reduced ungulate browsing frequency and intensity by concealing the oak seedlings and by sharing enemies (i.e. ungulate herbivores) with surrounding and more preferred shrub species, thus providing numeric dilution and associational plant refuges. The occurrence of naturally regenerated oak seedlings, five years after a conservation-oriented thinning, was negatively influenced by the presence of tall ground vegetation and positively influenced by high soil moisture. For oak seedlings planted in an open field, shrubs indirectly facilitated biomass accumulation by reducing competition from herbaceous vegetation. However, shrubs became net competitors three years after planting. The oak seedling response, in terms of biomass accumulation, transpiration and photosynthesis, to competition from shrubs was proportional to resource availability. Aboveground competition for light had a greater effect on oak seedling growth than belowground competition. Nevertheless, oak seedlings were able to produce a second shoot flush, over-topping the shrub canopy. This periodic flushing enabled light-acclimation in a stratified light environment. In conclusion, management of shrubs has the potential to reduce browsing and herbaceous competitors during oak regeneration, particularly during the first years after planting. Although shrubs alone may not replace fences as an effective means of reducing browsing on oaks, they provide a complement to improve the growth of seedlings during the early stages of establishment.
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| 2. |
- Lungu-Mitea, Sebastian
(författare)
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Toxicity pathways in zebrafish cell lines : an ecotoxicological perspective on "toxicity testing in the 21st century"
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Standard toxicological in vivo testing has been challenged as the procedures are time-consuming, expensive, and require a large number of animals; given the number of problematic chemicals. Novel toxicological frameworks, such as "toxicity testing in the 21st century", proposed the use of "new approach methods" (in vitro and in silico techniques), that can be applied in high-throughput setups and would allow for the testing of a large number of compounds. However, such new approach methods need to be designed and evaluated first. Especially within ecotoxicology, the coverage of species-specific bioanalytical tools, e.g. for fish, is rather scarce. Currently, mainly in vitro assays of mammalian and bacterial origin are used. This thesis outlines how to design and scrutinise fish transient reporter gene assays. We have established transient reporter gene assays in permanent zebrafish fibroblasts and hepatocytes of the oxidative stress response and the xenobiotic metabolism toxicity pathways. We identified non-specific effects caused by transient transfection itself and suggested preventive strategies. Further, we identified toxicity pathways’ cross-talk as a significant driver of uncertainty in regards to the assessment of receptor-mediated toxicity. Additionally, we evaluated the correlation between cytotoxicity in cultured zebrafish cells and the acute toxicity observed in zebrafish embryos. When using chemical distribution models to derive bioavailable concentrations, we observed a good positive correlation between the two test systems. The results advocate an intensified use of fish in vitro assays in integrated testing strategies. Conclusively, new approach methods, as developed and applied in this thesis, show great potential in future toxicity testing and environmental monitoring.
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| 3. |
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| 4. |
- Lamei, Sepideh
(författare)
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The effect of honeybee-specific lactic acid bacteria on american foulbrood disease of honeybees
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The honeybee, Apis mellifera, is one of the most economically important pollinators and highly valued for its honey and wax production. Managed honeybees occupy an increasingly critical role in agricultural productivity and food security. American foulbrood (AFB) is a highly contagious and destructive bacterial honeybee brood disease caused by Paenibacillus larvae that affects beekeeping worldwide. However, only a minority of bacteria associated with honeybees are harmful. Honeybee-specific Lactic Acid Bacteria (hbs-LAB), a defined group of beneficial bacteria inhabiting the honey crop, have strong antimicrobial properties important for honey production and honeybee health that could be exploited for combating diseases such as AFB. The aim of this thesis was to investigate the effect of hbs-LAB on P. larvae and AFB, both in culture, in individual larval bioassays, and at colony level. First we showed that the laboratory cultivation of the 13 distinct hbs-LAB was significantly improved by the addition of L-cysteine and fructose to the medium and optimized a culture-independent molecular technique for the detection and identification of the individual hbs-LAB species. Secondly the effect of the cell free supernatant, the secretome, from a culture mix of the 13 hbs-LAB species was investigated on P. larvae growth and associated larval mortality. The results showed that this secretome strongly inhibited the multiplication of P. larvae vegetative cells but that spore germination appeared to be unaffected, and that it decreased the mortality of P. larvae infected larvae. Finally it was shown that oral administration of hbs-LAB supplement to honeybee colonies had no influence on colony-level P. larvae spore levels or colony strength. Furthermore, the results showed that although the antibiotic tylosin decreased AFB symptoms in colonies, it had no effect on P. larvae spore levels. In conclusion, the colony-level results do not contradict the antagonistic effects observed in individual larvae in laboratory studies, but rather suggest that supplementary administration of live bacteria may not be the most effective way to harness such effects in a useful application.
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| 5. |
- Nilsson, Kerstin
(författare)
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To work or not to work in an extended working life? Factors in working and retirement decisions
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In most of the industrialised world, the proportion of older and retired people in the population is continuously increasing. This will have budgetary implications for maintaining the welfare state, because the active working section of the population must fund the non-active and old population. Aim: The overall aim of this thesis was to obtain knowledge about older workers’ work and life situation in association with their planning and decision to retire from working life. Method: The thesis includes one qualitative and three quantitative studies conducted in Sweden. Result: Self-rated health was found to be a better measure than diagnosed disease of whether older workers believed they could work until 65 years or beyond. Health seems not to be a general impediment to working in old age if older workers are satisfied with their work situation and have enough time and opportunities to recover from fatigue. In one of Sweden’s most hazardous work environments, older workers were not injured significantly more often than younger workers. Good mental and physical work environment, moderate working pace and working time, and the right competence and possibility for skills development were factors determining whether older workers believed they can extend their working life. Attitude to older workers in the organisation, motivation and work satisfaction were factors determining whether older workers want to extend working life. Health, personal economic incentives, family/leisure pursuits and attitude to pension in society affected both whether people believed they can and wanted to extend their working life. In their final retirement decision, older workers considered: i) their possibility to balance and adapt functional ageing and health to a sustainable work situation; ii) their economic situation; iii) possibilities for social inclusion and coherence; and iv) possibilities for meaningful activities. Whether these requirements were best fulfilled in or outside working life determined the decision to continue working or to retire. Conclusion: If it is desirable for society that people will to extend their working life, both the “can work” and the “want to work” factors need to be met. It is important to provide a good fit inside working life. This requires a focus not only on older workers, but also on organisations and managers in order to provide incentives that keep older workers in the work force.
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| 6. |
- Aballay, Erwin
(författare)
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Rhizobacteria associated to Vitis vinifera and their effect on the control of Xiphinema index, Meloidogyne ethiopica and Vitis growth
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Plant-parasitic nematodes are one of the most important pests affecting the growth of vineyards due to the destruction of new roots. Several species are associated with this problem, the most important being the ectoparasite Xiphinema index and the endoparasite Meloidogyne ethiopica. The search for new pest and disease control methods based on bioantagonist microorganisms is an important aspect of modern agriculture and the development of tools based on the use of rhizobacteria is becoming a widely evaluated alternative. The present study on suppressive soils started with a survey undertaken in productive Chilean vineyards to explore the younger roots of grapevines and identify the presence of rhizobacteria. More than 1800 soils were surveyed and a set of 11 vineyards were selected and considered suitable for bacteria isolation, as they showed low densities of plant-parasitic nematodes. A total of 400 bacterial isolates in 25 genera were obtained using tryptic soy broth agar and identified with fatty acid profiling. Two of the most frequently isolated species were Pseudomonas putida (35.1%) and P. fluorescens (6.1%). The effect of these isolates on the parasitism and reproduction of X. index was assessed through assays using potted vine plants (cv. Thompson Seedless) and a bacterial suspension containing 1×106 CFU/mL. Some isolates from Bacillus megaterium, B. brevis, B. mycoides, B. sphaericus, B. thuringiensis, Pseudomonas corrugata, P. putida, P. alcaligenes, P. savastanoi, P. fluorescens, P. pseudoalcaligenes, P. viridiflava, Stenotrophomonas maltophilia, Serratia plymuthica, Cytophaga johnsonae, Rahnella aquatilis, Stenotrophomonas sp., Variovorax paradoxus and Curtobacterium flaccumfaciens reduced root damage and suppressed populations. Isolates of B. brevis, Comamonas acidovorans, B. megaterium, Pantoea agglomerans and P. savastanoi increased plant growth or root weight, but did not control nematodes. Most of the culture filtrates obtained from isolates from four vineyards were effective in killing X. index and decreasing egg hatching, which was not related to damage or population control. It was estimated that 89, 32 and 16% of the isolates were effective against X. index under supernatant conditions, in potted plants growing in sterile substrate and in potted plants growing in field soil, respectively. Sixteen bacterial isolates previously assessed were also evaluated on M. ethiopica in vine cv. Chardonnay. Seven isolates (Serratia marcescens, C. acidovorans, P. agglomerans, Sphingobacterium spiritivorum, B. mycoides, Alcaligenes piechaudii and S. plymuthica) decreased damage or reproduction, showing that different species of nematodes can respond differently to a particular isolate.
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| 7. |
- Abd El-Daim, Islam Ahmed Moustafa
(författare)
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Use of rhizobacteria for the alleviation of plant stress
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Plant growth promoting rhizobacteria are beneficial microbes able to induce plant stress tolerance and antagonise plant pathogens. The present study showed that wheat seedlings pre-treated with Bacillus thuringiensis AZP2 had better tolerance to severe drought stress and showed 78% greater plant biomass and five-fold higher survivorship compared to wheat seedlings not treated with the bacterium. The effect of B. thuringiensis AZP2 also resulted in improved net assimilation and reduced emission of stress volatiles. The study investigated the effect of the inactivation of sfp-type phosphopantetheinyl transferase in plant growth promoting bacterium Paenibacillus polymyxa A26. The inactivation of the sfp gene resulted in loss of NRP/PK production such fusaricidins and polymyxins. In contrast to the former Bacillus spp. model the mutant strain compared to wild type showed greatly enhanced biofilm formation ability. Its biofilm promotion is directly mediated by NRP/PK, as exogenous addition of the wild type metabolite extracts restores its biofilm formation level. Further, increased biofilm formation was connected with enhanced ability of the sfp inactivated strain to remarkably protect wheat seedlings by improving its survival and biomass under severe drought stress conditions compared to wild type. Fusarium graminearum and F. culmorum are the causing agents of a destructive disease known as Fusarium head blight (FHB). The disease is the leading cause of contamination of grain with Fusarium mycotoxins that are severe threat to humans and animals. Biological control has been suggested as one of the integrated management strategies to control FHB causing agents. The present study showed that P. polymyxa A26 is a potent antagonistic agent against F. graminearum and F. culmorum. In order to optimize strain A26 production, formulation and application strategies traits important for its compatibility need to be revealed. Hence, a toolbox comprising of dual culture plate assays and wheat kernel assays including simultaneous monitoring of the FHB causing pathogens, A26 and mycotoxins produced was developed in the present study. Using this system results showed that, besides the involvement of lipopeptide antibiotic production by P. polymyxa in the antagonism process, biofilm formation ability may play a crucial role in the case of A26 F. culmorum antagonism.
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| 8. |
- Aboshady, Hadeer Moursy
(författare)
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Genomic variation and molecular mechanisms of the host response to gastrointestinal nematodes in small ruminants
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gastrointestinal nematode (GIN) infections are one of the major constrains for sheep and goat production worldwide. One of the promising control strategies is the genetic selection for resistant animals as there are no issues due to anthelmintic resistance and it aligns to demands for chemical-free food. Exploring possible phenotypic and genomic markers that could be used in breeding scheme besides understanding the mechanisms responsible for resistance were the main goals of this thesis. Thesis consists of General introduction, a brief description of GIN biology and methods to control GIN with focus on phenotypic and genomic markers, four papers and General discussion. In paper Ⅰ, a systematic review and meta-analysis were conducted to re-analyse and summarize the findings on immunoglobulins response to GIN in the literature and discuss the potential to use immunoglobulins as biomarkers of the host resistance. A conceptual model summarizing the role of immunoglobulins in resistance to GIN is proposed. In paper Ⅱ, transcriptome profiling of the abomasal mucosa and lymph node tissues were compared between non-infected, resistant and susceptible Creole goats experimentally infected with Haemonchus contortus. Results indicated that the maintenance of the integrity of the mucosa has probably the priority for the host at late infection stage. In paper Ⅲ, the dynamics of the response of the abomasal mucosa of resistant and susceptible Creole goats experimentally infected with H. contortus were compared. The immune response was activated through many relevant pathways including the Th1 immune response at different time post-infection. Interestingly, the results showed a simultaneous time series activation of Th2 related genes in resistant compared to susceptible kids. In paper Ⅳ, the genomic variants of Creole goats resistant and susceptible to H. contortus were discovered from RNAsequencing data at four different times post-infection. Single nucleotide polymorphisms, insertions and deletions that distinguish the resistant and the susceptible groups were identified and characterized through functional analysis. The T cell receptor signalling pathway was one of the top significant pathways that distinguish the resistant from the susceptible group with genomic variants in 78% of genes in this pathway.
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| 9. |
- Abrahamsson, Malin
(författare)
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Patterning during embryo development in Pinus : with special emphasis on somatic embryogenesis in Scots pine (Pinus sylvestris L.)
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Somatic embryogenesis is an attractive method to propagate conifers vegetatively. However, many species belonging to Pinus are recalcitrant to somatic embryo development. The overall aim of this thesis has been to gain a better understanding of the developmental pathway leading to cotyledonary somatic embryos of Scots pine (Pinus sylvestris). By comparing the developmental pathway of somatic embryos in a normal and in an abnormal cell line, differences between the cell lines were identified. An important difference was the high ratio of early and late embryos carrying supernumerary suspensor cells in the abnormal cell line compared to embryos in the normal cell line. This unbalanced ratio between the embryonal mass and the suspensor is at least partly caused by a disturbed polar auxin transport. Furthermore, a high proportion of early and late embryos degenerated in both cell lines. The degenerating embryos in the normal cell line were eliminated in a similar way as subordinate embryos in the seed. Contrastingly, the degenerating embryos in the abnormal cell line were not eliminated; instead the degenerated embryos started to differentiate new embryos creating a loop of embryo degeneration and embryo differentiation. During initiation of embryogenic tissue, the protruding early zygotic embryo(s) started to degenerate before a proliferating embryogenic culture was established, indicating that the initiation of embryogenic cultures is not a direct continuation of cleavage polyembryony. The results further suggest that there is a high risk that cell lines initiated from early zygotic embryos at the stage of cleavage develop abnormally. To be able to use more differentiated tissues as explants for initiation of embryogenic cultures, more knowledge is needed about totipotence and embryogenic potential. Treatment with the histone deacetylase inhibitor trichostatin A (TSA) during maturation of somatic embryos of Norway spruce inhibited the maturation progression of the embryos. Furthermore, although TSA-treatment maintained the embryogenic potential in germinating somatic embryos, it did not enable the embryos to regain embryogenic potential after it was lost. By analysing global changes in gene expression during early zygotic embryo development in Scots pine, we identified genes and processes that might be important for regulating the cleavage process and for the development of a dominant embryo. Together these results contribute to the knowledge that in turn can lead to improved protocols for large scale propagation of Pinus species via somatic embryos.
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| 10. |
- Abrahamsson, Sara
(författare)
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Genetic dissection of quantitative traits in Scots pine
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The phenotypic expressions of Scots pine, have been extensively studied over the years, but the gene regulation behind the traits has only just begun to be elucidated. The overall aim of this thesis was to start dissecting the genetics behind a number of adaptive traits in Scots pine and examine how they are influenced by relatedness using different molecular tools. In a full-sib family of Scots pine the genetic variation in autumn frost hardiness and height growth was revelead by measuring open-pollinated offspring. A significant genetic variation for both traits was found, a prerequisite to identify quantitative trait loci (QTL). A conceptual statistical model in the Bayesian framework for identifying QTLs in dynamic traits i.e. traits that vary over time, was developed and applied in a QTL study based on a full-sib family of 250 trees. A set of 160 AFLPs were utilized. QTLs for three latent traits were identified: one for the slope (growth) and two for the quadratic term (growth cessation). As a tool to identify candidate genes for the study of quantitative adaptive traits, gene regulation under continuous red (cR) and far-red (cFR) light was studied in hypocotyls from open-pollinated seeds from a natural population in northern Sweden using microarray technology. The gene expression patterns for the light response pathway in Scots pine under cFR show clear differences from those of angiosperms, wherein we observed up-regulation of cryptochrome1. This gene has, therefore, become a strong candidate gene that deserves further studies to elucidate the genetics behind Scots pine adaptation. Not knowing the genetic relationship and inbreeding of trees, and how it influences the phenotypic expression, can lead to over- or underestimation of additive genetic values resulting in biased heritability estimates. A natural population of Scots pine, earlier identified as being highly inbreed, was used to investigate the influence of inbreeding by the correlation between heterozygosity and propotion of sound seed (PSS), average seed weight and proportion of rare alleles (PRA). Heterozygosity fitness correlation (HFC) was found positive for PSS and negative for PRA most likely due to recessive deleterious alleles purged in homozygotes. The study provided evidence that, as predicted by theory, inbreeding enhances HFC in a species with high outbreeding rate and high number of lethal equivalents as Scots pine.
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| 11. |
- Abro, Rani
(författare)
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Digestion and metabolism of carbohydrates in fish
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the digestion and metabolism of carbohydrates in Arctic charr, Eurasian perch and tilapia. Two sources of carbohydrates, native starch (wheat) and chitin (zygomycete biomass), were evaluated. Gut tissue of Arctic charr displayed significant chitinase activity, of both endo- and exo-chitinase forms. Moreover, the distribution pattern along the gastrointestinal tract of Arctic charr differed between endo-chitinase and exo-chitinase. The endo-chitinase activity in stomach tissue and in the distal intestine was several hundred-fold higher than the exo-chitinase activity in stomach tissue. The greatest exo-chitinase activity was found in the distal intestine fed a zygomycete-based diet. Disturbed intestinal integrity and increased uptake rate of the amino acid lysine were observed in the distal, but not proximal, intestine of fish fed the zygomycete-based feed. A ¹HNMR metabolomics approach revealed no differences in metabolic profile in liver tissues of Arctic charr fingerlings fed a zygomycete-based diet and a fish-meal based diet. The inclusion of wheat starch did not affect α-amylase activity in gut tissue of Arctic charr and Eurasian perch. Overall, α-amylase activity was correlated with the trends obtained for starch digestibility. The apparent digestibility (AD) of crude protein, starch, crude fat and energy differed between the fish species, with on average higher values for all parameters in Eurasian perch than in Arctic charr. Within fish species, dietary starch level had no effect on AD of dry matter, crude protein, crude fat and energy. Studies of the metabolic response to wheat starch inclusion in Arctic charr and tilapia using ¹HNMR base metabolomics indicated metabolic effects in tilapia, while inclusion of starch in the diet of Arctic charr resulted in partial or negligible metabolism effects. Thus there are species-related differences in the metabolic response to dietary starch inclusion.
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| 12. |
- Abro, Shahid, hussain
(författare)
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Molecular characterization and detection of infectious bronchitis virus
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the molecular characterization and detection of infectious bronchitis virus (IBV), an important pathogen that causes heavy losses in the poultry populations worldwide. The aim of the research was to better understand the molecular characteristics of the virus and to investigate the factors behind the continuous emergence of new genetic variants and the occurrence of outbreaks. The studies showed that the viral genome is under a continuous evolution, due to mutations, strong selective pressure and recombination events. These forces lead to a wide genetic diversity and the generation of new variants of this virus. The viral genes encoding the spike, envelope and membrane proteins can be considered the main genomic regions, which are indicating the evolution processes of IBV. The various strains contain specific structural and functional motifs in their genes and the alterations in these motifs may affect the infection biology of the virus. The constant emergence of new variants in Sweden is likely due to the introduction of novel IBV strains from other European countries through the import of poultry products, or by the continuous migration of wild birds. The in silico investigations of the spike glycoprotein coding regions of the Massachusetts and QX-like genotypes demonstrated molecular differences between these genotypic variants. It is hypothesized that the genetic diversity in the spike gene of IBV and of other avian coronaviruses, as well as of human, bat, and other animal coronaviruses could be associated with the adaptation and host specificity of these infectious agents. The data obtained by molecular characterization approach was also used for the development of a new molecular method for the improved detection and genotyping of this virus. A microarray platform was developed for the simultaneous detection and rapid typing of IBV variants. This assay provides a practical tool for better diagnosis, for studying the effectiveness of vaccination and for performing large-scale epidemiological studies.
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| 13. |
- Abubaker, Jamal
(författare)
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Effects of fertilisation with biogas residues on crop yield, soil microbiology and greenhouse gas emissions : recycling of plant nutrients from bioenergy production
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The amount of residues generated by biogas production has increased dramatically due to worldwide interest in using renewable energy. Biogas residues (BRs) originate from anaerobic degradation of different types of rural and urban organic wastes and have been proposed as organic fertilisers because of their high content of ammonium and other valuable macro- and micro-nutrients. However, application of BRs to agricultural soils may be accompanied by environmental risks, since they may contain heavy metals and organic pollutants. Therefore the effects of BRs on crop production and on the soil ecosystem and environment urgently need to be investigated before their wider use. This thesis evaluated and compared different types of BRs against cattle slurry, pig slurry, compost and mineral fertiliser with respect to their (1) ability to provide plants with necessary nutrients, (2) impact on the soil microbial ecosystem and (3) effects on emissions of the greenhouse gas nitrous oxide (N₂O). The results from short-term laboratory experiments and a long-term field trial showed that BRs increased crop yield to the same extent or more than conventional mineral fertiliser and compost, but less than pig slurry. BRs generated from source-separated organic household waste had a tendency to give higher crop yield and soil microbial activities than other BRs. BRs had no general negative effect on soil respiration, but substrate-induced respiration decreased significantly in organic soil on addition of BRs. Although all BRs initially inhibited potential ammonium oxidation and potential denitrification activity, no long-term negative effects were detected. BRs stimulated ammonium assimilation, which can temporarily decrease nitrogen availability to the plant. Furthermore, the bacterial community structure in the sandy soil was altered by BRs and cattle slurry, but no significant change was seen in the community structure of clay and organic soil. Application of BRs and animal slurry increased N₂O emissions, but the total losses and flux patterns were affected by fertiliser type and soil type. In conclusion, the fertiliser value of BRs should be regarded as high and they apparently have no long-term adverse effects on soil microbial functions and structures. Thus the problematic amounts of residues associated with expansion of biogas production could be turned to advantage, as these residues seem to be safe and competitive fertilisers.
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| 14. |
- Adevi, Anna
(författare)
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Supportive nature - and stress : wellbeing in connection to our inner and outer landscape
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many benefits are claimed for the interplay between humans and nature, such as nature’s potentially positive effect on wellbeing and health. The main aim with the present work was to increase the understanding of how nature nvironments can support and contribute to health improvement from stress related experiences. Different landscape types’ effect on stress was studied in Sweden. Single case-studies focused on factors considered being essential in the recovery process for people diagnosed with exhaustion disorder within a stress rehabilitation-program through garden therapy in Alnarp, Sweden. A simplified conclusion of the thesis would be that the childhood landscape seems to play a significant role affecting the choice of the adult’s recreational setting - and recreational activity when stress is included. People feel more at home in the type of landscape they grew up in and more often chose to settle down in this type of landscape; even if they have moved from their childhood region. People also prefer qualities connected to their childhood landscape, but seem to attach more easily to qualities suggested having innate significance. The stress-recovery process within the garden therapy seems to be supported, hastened and deepened because of a multisensory change in awareness when contact with nature is combined with therapeutic interventions. Different psycho-physiological processes are discussed as well as the importance of self-chosen places in the garden based on present mood and the significance of the interaction between symbolic and concrete activities. The garden, the caregivers, and the group of participants together make up an arena which combines structure with freedom of action, in which the participants get the chance to regulate their needs and desires. Two hypotheses are presented, which might contribute to filling some current gaps in knowledge regarding the potential benefits of human interactions with nature.
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| 15. |
- Adler, Karl
(författare)
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Digital soil mapping and portable X-ray fluorescence prediction of cadmium, copper and zinc concentrations as decision support for crop production
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Trace element concentrations in agricultural soil are important for crop production. Certain trace elements, e.g. copper (Cu) and zinc (Zn), are essential for crops to complete their life cycle. Other trace elements, e.g. cadmium (Cd), can be harmful to crops or the end-consumer. Hence, it is important to have maps of soil concentrations of trace elements or methods for determining concentrations in soil samples. This thesis investigated the possibility of predicting trace element concentrations (Zn, Cu, Cd) in soil samples using portable X-ray fluorescence (PXRF) measurements. It also examined usefulness of digital soil mapping (DSM) to create maps of Cu and Cd concentrations in agricultural topsoil in Sweden.Portable X-ray fluorescence models were validated at national and farm level. Predicted Zn concentrations were found to be comparable to those obtained in conventional laboratory analysis, while predicted Cd and Cu concentrations were less accurate. The most accurate PXRF models were created using non-linear machine learning algorithms, e.g. random forest.Digital soil mapping of Cd concentrations in Skåne County, combined with data from grain sampling, revealed that low Cd concentrations in winter wheat grain were associated with predicted low concentrations in soil. The map could thus be used to identify arable soils suitable for producing winter wheat for products with strict quality criteria, e.g. baby food. Digital soil mapping of Cu concentrations at national level revealed that 47% of arable soils are highly likely not at risk of Cu deficiency. Covariate importance analysis indicated importance of airborne gamma radiation measurement data in DSM of Cu and Cd concentrations.
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| 16. |
- Adom, Philip Kofi
(författare)
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Energy demand management in selected African countries
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis contains five empirical papers that contribute to the energy demand management literature on Africa. It investigates the following policy issues – business cycle and energy conservation, government fuel subsidies and energy efficiency, economic growth and environmental quality, structural effects in parameters, the transition between energy efficiency and energy inefficiency, forecast of energy demand, shifts in demand behaviour, and the persistence profile of energy demand to shocks – using data from five countries: Algeria, Nigeria, South Africa, Cameroon and Ghana. In terms of contribution, this thesis provides the first empirical attempt to investigate the transition between energy efficiency and energy inefficiency; provides a comprehensive analysis of road transport energy demand and the implications of structural breaks for model parameters; provides evidence to support the fact that economic growth and environmental quality are jointly achievable, and argues that there is an income state that drives investment in energy efficiency. The main results of the thesis are as follows. First, low income state does not promote investment in energy efficiency. Second, reducing or withdrawing government fuel subsidies will enhance energy efficiency. Third, investment in technology in the industrial sector is a likely panacea to integrate the goals of economic growth and environmental quality. Fourth, the existence of structural breaks in the data significantly changes how price of crude oil, FDI, economic structure and trade openness promote energy efficiency. Fifth, the characteristics of industries and technology absorptive capacity of countries significantly facilitate energy savings in FDI. Sixth, the duration of an energy inefficient state is about twice as long as an energy efficient state, mainly due to fuel subsidies, low income, high corruption, regulatory inefficiencies, poorly developed infrastructure and undeveloped markets. Finally, diesel and gasoline fuels differ in many respects which suggest that a discriminatory tax policy would be an appropriate tax policy than a uniform tax policy.
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| 17. |
- Adu, George
(författare)
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Studies on economic growth and inflation : theory and empirics
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of four independent papers. Paper I examines the effect of environmental policy on economic growth in a small open economy in a neoclassical framework with pollution as an input. We show that the effect of environmental policy on growth is stronger in the open economy case relative to the closed economy model if the country has strong aversion to pollution and thus serves as a net exporter of capital in the international capital market. On the other hand, if the agents in the economy have low aversion to pollution and thus import capital, the effect of environmental care on growth is stronger in the closed economy relative to the open economy. Paper II analyses the effect of asymmetry in factor endowments between resource-rich and resource-poor countries on equilibrium bias of technology development and adoption possibilities. First, we show that the bias in equilibrium technology in the resource-poor North is determined by its relative abundance of human capital and physical capital. Secondly, we show that the equilibrium bias in technology in the resource abundant South is dependent positively (negatively) on the relative abundance (scarcity) of skilled (unskilled) labour and the relative abundance (scarcity) of physical (natural) capital in the North. This force is dampened by the relative scarcity of skilled labour and physical capital in the South. These forces drive wage inequality, high cost of capital and skill technology mismatch in the South, all of which are bad for growth. These effects cumulatively, explains part of the observed differences in growth performance between resource -rich and resource-poor countries. Paper III investigated the relationship between long run economic growth in Ghana and natural resource abundance using time series econometric techniques. Using a number of indicators that could proxy for resource abundance in eight alternative specifications, the results rejected the resource curse hypothesis. Paper IV provides an empirical analysis of the factors accounting for inflation dynamics in Ghana using the bounds test and other econometric approaches. We find that real output, nominal exchange rate, broad money supply, nominal interest rate and fiscal deficit play a dominant role in the inflationary process in Ghana.
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| 18. |
- Agostinelli, Marta
(författare)
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Fungal assemblages in forest trees : influence of internal and external conditions
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Forest trees host a plethora of microorganisms (bacteria, viruses, fungi) whose roles and diversity are still poorly understood despite the increased scientific interest for the past decades. The thesis focuses on the diversity of endophytic and epiphytic fungi in the aerial tissues of broadleaved trees. It tests a basic hypothesis that the diversity and frequency of endophytic and epiphytic fungi vary depending on the vitality and disease susceptibility of the host. Additionally the thesis explores if the chemical variation in trees may relate to differences in fungal community. Particularly, the aim was to describe how the fungal communities of three broadleaved species relate to the general vitality or specific pathogen resistance of the trees, and if herbivory or fertilization influence the fungi through altered levels of potentially antimicrobial metabolites, condensed tannins. Culture-based and culture-independent (NGS) techniques were used to capture the fungal community in the twigs of pedunculate oak (Quercus robur L), in the leaves of aspen (Populus tremula L), and in the leaves and twigs of European ash (Fraxinus excelsior L). The secondary metabolites were studied with HPLC, LC-MS, and GC-MS analyses. The results showed that the fungal assemblages are influenced by a complex network of factors related to the status of the host (internal factors: health, chemotype) and its environment (season, site, nitrogen, herbivory). Trees with different vitality or different phenotypic response to pathogen hosted quantitatively and qualitatively diverse fungal communities. Tissue type and seasonal variation were confirmed to be highly selective factors in shaping fungal communities of forest trees. The endophytic communities associated with xylem seemed to be shaped by the tree vitality more readily than the fungi associated with leaf or bark. Condensed tannins, nitrogen fertilization, and herbivory did not explain the structure of fungal communities in aspen leaves. Leaf phenolic metabolites reflected well the general vitality phenotype of the trees, but the relationship between fungi and phenolics may not be straightforward. The technological advances and the use of different methods to survey fungal communities may help disclosing the unknown fungal biodiversity hosted by forest trees. Further studies on fungal communities are needed to reveal the ecological relevance that fungal assemblages have in the regulation of major ecological cycles. Understanding the mechanisms regulating the establishment of fungal communities may contribute to the possibility of using fungal assemblages in forest practices to help forest coping with sudden changes and be able to provide different ecosystem services.
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| 19. |
- Agstam, Oskar
(författare)
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Restoration of Nutrient Rich Lakes - Towards Better Understanding of Sediment Phosphorus Availability and Management
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lakes are important for many reasons as they provide valuable ecological and human services, such as drinking water and recreational use. Eutrophication, a result of excess nutrients (e.g. phosphorus (P)) in lakes, is a threat to these resources, causing impairment of water quality. Excess P loading to lakes accumulates in the sediment, consequently making sediment a potential source of P via release (internal loading). One way of counteracting effects caused by internal loading is to inactivate the pool of potentially available P in the sediment. Better information is needed for optimizing most in-lake P reduction methods, including aluminum (Al)-treatment. One of these areas is better knowledge about the availability of different P fractions, and which fractions to target with a specific dose of Al under certain environmental conditions such as bioturbation (e.g. sediment mixing by carp). We also need to deepen the knowledge about modern Altreatment methods, with respect to both treatment techniques and dosing. Knowledge about factors affecting how long the positive effects from an Al-treatment last also needs to be improved. This thesis presents results concerning optimization of Al application methods, where a novel application method that injects Al into the sediment was evaluated and a model for optimal Al dose determination is presented. Factors affecting treatment longevity were evaluated, using historical water quality records and knowledge about a previously assumed recalcitrant P form being bioavailable due to bioturbation by benthic feeding fish like carp and bream. Al-treatment methods, including practical Al application methods as well as dosing methods are developing rapidly and being applied in the field, and further work is needed to keep up with evaluating the progress of lake restoration results using methods like Al-treatment.
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| 20. |
- Aguilera Nuñez, Guillermo
(författare)
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Local and landscape-level impacts of agricultural intensification on arthropod communities and their interaction networks
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Arthropods play a central role in agricultural landscapes being responsible for the delivery of many ecosystem services such as pollination, biological pest control, and nutrient cycling. But the current global decline of arthropods is intensified by habitat modification, loss and fragmentation, pesticide use and other intensive management practices. Thus, it is crucial to understand how such impacts affect ecosystem services provisioning. In this thesis, I aim to explore how the management of local crop fields and landscape composition affect beneficial arthropod communities at different levels, including abundances and diversity of species and species interaction networks. I focus on predaceous and parasitic insects that provide biological pest control and pollinators. I assess i) how crop diversity affects arthropod diversity, ii) how fertilisation affects the local predator community and pest control, iii) how crop type (annual vs perennial) and landscape composition affect the predator-prey and host-parasitoid interaction networks and the implications for pest control. I found that increasing crop diversity in landscapes with a high proportion of seminatural habitats can enhance the diversity of beneficial arthropods. I also detected that organic fertilisation can benefit the abundance of local predators while specialist predators that move into the crop from the surrounding habitats boost biological pest control. I also found that crop type and landscape composition have effects beyond community species composition as also the interaction networks were altered, modifying the network stability and pest control potential. My findings suggest that the main drivers of change in agricultural landscapes affect arthropod communities at different levels. Effects of habitat type and local management can be observed not only in the community composition, but some of the consequences were also reflected in the species interaction networks. Finally, I show that food web ecology can link community composition and ecosystem service provisioning.
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| 21. |
- Ahlberg, Viktor
(författare)
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Innate immune responses to a saponin adjuvant in the pig : application of gene expression profiling
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vaccination is one of the most powerful ways to prevent infectious diseases. Successful vaccines produce a long-term immunity including effector T and B lymphocytes. In this context, adjuvants have a key role in vaccines by stimulating the innate immunity and thereby enhancing and shaping the subsequent adaptive immune response. The aim of this thesis was to elucidate the early innate immune response to the saponin-based adjuvant Matrix-M in the pig. Gene expression profiling was applied to monitor the global transcriptional response to Matrix-M in vivo. The innate immune response was further characterized by quantitative PCR analysis in vivo and in vitro and the early immunomodulatory effect of Matrix-M was evaluated in a contact exposure model. A mild inflammation and a cellular influx were recorded at the injection site and in the draining lymph node 24 hours after intramuscular injection of Matrix-M in pigs. In accordance, microarray analysis detected transcriptional alterations of genes for cytokines, chemokines and pattern recognition receptors in both tissues. Interferon- regulated genes were significantly overrepresented in these tissues, accompanied by increased gene expression for interferon-β in in the draining lymph node and interferon-α in blood. Transcriptional responses to Matrix-M in vitro were generally low but increased culture and exposure time affected genes for pro-inflammatory cytokines and TH cytokines in lymphocytes. Low levels of interferon-α gene expression were also detected in monocyte-derived dendritic cells. A contact exposure model was established to mimic field conditions when allocating grower pigs, by mixing pigs of various health statuses. After transport and mixing with conventionally reared pigs, all specific pathogen free (SPF) pigs in this model developed respiratory disease. Systemic symptoms that correlated with granulocyte counts, serum amyloid A levels and transcription of IL18 and TLR2 were provoked in two out of four SPF pigs that received saline prior to exposure, but not in those given Matrix-M. Taken together, the application of gene expression profiling successfully identified the induction of innate immune responses in porcine tissues and indicated that Matrix-M primes the host for further immune regulation. Thus, Matrix-M or similar saponin formulations are potentially useful clinical immunomodulators or adjuvants in emergency vaccines.
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| 22. |
- Ahlbäck Widenfalk, Lina
(författare)
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Springtails in space : factors structuring Collembola populations and communities, revealed by trait-based analyses
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The relative influence of environmental conditions, biotic interactions and dispersal limitation for community structure and diversity patterns is a reoccurring theme in community ecology. In studies of soil fauna communities, small-scale horizontal and vertical variations in environmental variables and biotic interactions have often been disregarded, despite these being key factors to understanding the diversity of soil fauna communities. In this thesis I examined the spatial distribution patterns of springtail (Collembola) species and communities in three different ecosystems: a salt marsh, mature pine forests and a high Arctic tundra meadow. The different systems consisted of a, to the human eye, homogeneous habitat. Still, they had different regimes and small-scale heterogeneity in environmental variables. In the three first studies the focus was on species and trait composition and diversity, at scales from 10 cm to 300 km. In the fourth paper I question the use of species-level analyses of distribution patterns, as different age classes within a species might be structured by different factors. I found that when habitat conditions were kept as similar as possible, the pine forest Collembola communities had similar functional diversity, although there was a high species turnover both between samples within study sites and between sites. The functional similarity between samples was lower in the salt marsh habitat, a habitat characterized by frequent inundation events. The small-scale variation in species and trait composition was best explained by spatial variables in the stable mature pine forest floor, while in the dynamic salt marsh environmental variation was most important. Coexisting species showed a higher difference in traits than expected in the pine forest, while coexisting species were similar in traits in the salt marsh. This indicates that species interactions can have a large impact on the community composition of springtails at small spatial scales. Small-scale niche partitioning may be one explanation for the high local diversity observed in many soil communities. I found that incorporating species-specific trait information in studies greatly helps our understanding of the mechanisms structuring communities, despite the finding that in some species of collembolans different age classes may use space differently. To improve our understanding of Collembola communities both these factors should be considered in future studies.
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| 23. |
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| 24. |
- Ahlman, Therese
(författare)
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Organic dairy production : herd characteristics and genotype by environment interactions
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis was to gain further knowledge about the performance of cows in organic dairy production and their ability to adapt to the organic production environment. Milk production traits, fertility traits, somatic cell count (SCC) and longevity traits were analysed in organic and conventional herds and the reasons for culling in the two systems were investigated. Furthermore, the genetic correlation between traits expressed in organic and conventional production was estimated to assess the occurrence of genotype by environment interaction (GxE). The data contained records from almost all organic and conventional herds in Sweden. This thesis shows that performance of organically managed dairy cows differs from conventionally managed cows. Cows in organic herds had lower production, better fertility and higher SCC than cows in conventional herds. However, the performance of cows in organic production depended to a large extent on the lower milk production level. At a given production level, organically managed cows had slightly worse fertility but equal SCC as cows in conventional herds. Cows stayed longer in organic herds than in conventional herds and the main reason for culling differed between the production systems. The main reason for culling in organic production was poor udder health followed by low fertility. In conventional production the main reason for culling was low fertility followed by poor udder health. The results indicate that organic farmers are more concerned about udder health than conventional farmers are. Genetic correlations for production, fertility, SCC and longevity, estimated in organic and conventional dairy production were in general close to unity. The results indicate that current breeding values for Swedish Red bulls, estimated in conventional production, are adequate for organic production. Weak GxE was found for fertility traits in Swedish Holstein cows, indicating that some cows of this breed are better suited for organic production than others. However, the magnitude of GxE does not justify development of a separate breeding programme for the organic population today.
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| 25. |
- Ahlström, Martin
(författare)
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Stand development and growth in uneven-aged Norway spruce and multi-layered Scots pine forests in boreal Sweden
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The use of the selection system has always been a marginal part of Swedish forestry, and so has research about the system under Swedish conditions. However, the interest in Sweden for uneven-aged forest management has increased because of a rising concern for the ecological and aesthetical consequences from use of the dominating rotation forests system, which creates even-aged forest and has clear-cutting as primary harvesting method. In this thesis I have studied the possibilities and limitations of the selection system in Swedish boreal forests. Stand development, ingrowth and volume increment has been studied in both Norway spruce (Picea abies (L.) H. Karst.), and Scots pine (Pinus sylvestris L.) forests. My studies of uneven-aged Norway spruce show that 1) these forests have the capacity to spontaneously create and maintain an uneven-aged stand structure, 2) there is a positive relation between standing volume and volume increment, and 3) there is no clear relation between the level of ingrowth and stand density. My studies of multi-layered Scots pine forests show that 1) a multi-layered stand structure is more likely the result of size stratification and not of continuous ingrowth, 2) There is positive relation between standing volume and volume increment, and 3) that a low stand density is seems required for ingrowth to occur on a sustainable level. The results imply that for boreal Norway spruce forests, a high standing volume would be recommended when the selection system is applied, whereas for boreal Scots pine forest, uneven-aged management should be motivated by other values than stem production, e.g. aesthetical or ecological.
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| 26. |
- Ahmad, Iftikhar
(författare)
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New insights into plant amino acid transport and its contribution to nitrogen nutrition
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nitrogen (N) is a crucial element for plant growth and development, as it is a key constituent of numerous plant metabolites and structural components. However, most plant N is in the form of amino acids, which are building blocks of proteins, precursors of many secondary metabolites and the “currency” of N within plants (i.e. the form in which N is transported and transferred). Recent studies have shown that amino acids are prevalent in soils and may also serve as N sources for plants. This thesis (and four appended papers) focuses on these aspects of amino acids, particularly the molecular mechanisms of amino acid transport in plants and their potential contribution to plants N nutrition. In Arabidopsis thaliana (Arabidopsis) at least 67 genes are annotated as putative amino acid transporters. In this thesis, results are presented suggesting that two amino acid transporters, LHT1 and AAP5, in Arabidopsis play important roles in amino acid uptake from soil at field-relevant concentrations (Paper I). This conclusion is based on the uptake characteristics of mutant plants (lht1, aap5 and lht1xaap5), displaying very little residual root uptake of amino acids. Furthermore, these two transporters have complementary affinity spectra: LHT1 for acidic and neutral amino acids; and AAP5 for basic amino acids. To probe the disputed contribution of organic N to plant N nutrition, mutants with both suppressed and enhanced expression of LHT1 were grown in agricultural soil. The results indicate that plants can take up significant amounts of amino N, despite microbial competition, suggesting that uptake of amino acids contributes to plant N nutrition (Paper II). Moreover it was shown that disrupted N cycling in leaf mesophyll cell affects leaves of different developmental status differently with respect to N and C status. Thus amino acid transport is critical for the maintenance of C and N status and leaf metabolism and LHT1 plays a key role in the process (Paper III). To broaden the studies from herbaceous plants to trees, a Populus orthologue of LHT1 (PtrLHT1.2) was identified. The PtrLHT1.2 gene from Populus tremula L. x tremuloides Michx. was cloned and expressed in a LHT1 uptake mutant of Arabidopsis. Results of its heterologous expression in Arabidopsis suggest that PtrLHT1.2 is a functional orthologue of AtLHT1 (Paper IV), indicating that PtrLHT1.2 could be involved in root amino acid uptake in Poplar tree.
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| 27. |
- Ahmadi Afzadi, Masoud
(författare)
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Genetic variation in resistance to fungal storage diseases in apple : inoculation-based screening, transcriptomics and biochemistry
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Apple is one of the economically and culturally most important fruit crops and has many health-related benefits. Apple production is, however, sensitive to several fungal diseases including blue mold, caused by Penicillium expansum. Problems are more pronounced in organic production or in countries where postharvest application of fungicides is prohibited. To limit or overcome this problem, many studies have been focused on investigations of the mechanism of resistance/tolerance. No major gene(s) have as yet been identified, but quantitatively inherited traits, some of which are related to fruit texture and content of chemical compounds, have been shown to affect the ability of cultivars to withstand storage diseases. In the present thesis, inter-cultivar variation in terms of resistance to fungal storage diseases was investigated at two locations, i.e. Balsgård in Sweden and Njøs in Norway. The association of harvest date, fruit firmness and softening with lesion decay was investigated on large sets of cultivars. The contribution of four fruit texture-related genes (Md-ACO1, Md-ACS1, Md-Exp7 and Md-PG1) in explaining the fruit texture characteristics was examined. Fruit content of chemical compounds with a potential impact on disease resistance was also investigated, and finally the regulation of apple genes upon fungal infection was studied in order to identify candidate genes responsible for disease resistance. Inoculation-based screening indicated large variation across the investigated cultivars in terms of blue mold and bitter rot susceptibility. Harvest date and softening rate of fruits during storage had a large impact on resistance to fungal diseases, thus cultivars with moderate to firm fruits that soften comparatively little during storage could withstand the fungal infection comparatively well. Softening rate is, in its turn, closely associated with harvest date whereas four fruit texture-related genes had lower predictive power than expected. Quantifying the chemical compounds in the fruit samples revealed that some of these compounds, especially flavonols and procyanidin B2, could contribute to resistance against blue mold, whereas contents of malic acids or total titratable acidity had considerably less impact. Differential expression of FLS, LDOX, and CHS genes involved in biosynthesis of flavonoids and PGIP, TT10, WAK1 and CTL1 genes related to cell wall structure indicate the importance of fruit characteristics and biochemical compounds in the resistance mechanism.
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| 28. |
- Ahmadi Moghaddam, Elham
(författare)
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Life Cycle Assessment of Novel Biomethane Systems : energy performance and climate impact
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Climate mitigation and supply of renewable energy are global challenges. The main cause of climate change is anthropogenic activities, including consumption of fossil energy sources and land use change. Biomethane, a biomass-derived renewable energy carrier, is interchangeable with fossil-based natural gas and can provide energy services (e.g. heat, electricity and vehicle fuel) and high-value products such as chemicals. However, the availability of feedstock suitable for anaerobic digestion, the limited grid infrastructure in certain regions and problems relating to storage and distribution are barriers to increased deployment of biomethane systems. This thesis aims to provide decision support for the development and implementation of future biomethane systems, by describing the energy performance and climate impact of some promising novel technologies related to biomethane production, conversion of biomethane to high-value products and biomethane distribution in a life cycle perspective. Anaerobic digestion of maize and pyrolysis of willow for production of biomethane were assessed and compared, while gas-to-liquid (GTL) technologies were studied as potential routes for conversion of biomethane to liquid transportation fuels or platform chemicals. Gas hydrates were assessed as a means of biomethane distribution. The results showed that transition from maize-based anaerobic digestion to willowbased pyrolysis for biomethane production improved energy performance (higher external energy ratio) and environmental performance (lower climate impact), mainly due to buildup of soil organic carbon and use of biochar as a soil amendment or as an energy source to replace fossil coal. Use of biomethane for production of dimethyl ether as a GTL fuel was competitive relative to the conventional compressed biomethane system regarding energy performance and climate impact. Formation and disassociation of gas hydrates was associated with high energy use, and thus technological development is required to overcome the high primary energy inputs and related high climate impact of gas hydrate distribution.
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| 29. |
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| 30. |
- Ahsan, Muhammad
(författare)
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Mapping and functional characterization of candidate genes and mutations for chicken growth : an approach combining computational genetics and bioinformatics
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Knowledge of the genetics related to growth is important for breeding chickens with the desired traits of rapid and efficient growth. A long-term selection experiment in the domestic chicken (Gallus gallus) has resulted in two highly divergent lines selected for juvenile body weight. These lines are a great genetic resource to identify the genetic basis of phenotypic variation mainly for growth traits. The aim of this thesis was to map the relationship between the genotype and phenotype and thereby reveal the genetic architecture of growth in the chicken. To this end, high-density genotyping and whole-genome resequencing of the lines were used to explore the genetics of the body weight difference between these lines. We further fine- mapped previously identified Quantitative Trait Loci (QTLs) for body weight and used bioinformatics approaches to identify the most promising candidate genes, mutations and biological pathways for growth for further functional evaluations. We also studied a previously mapped radial network of interacting QTLs to reveal potential biological interactions by analyzing biological pathways. In addition, we developed new computational genetic method and tools and used them to functionally explore specific genetic variants in selected regions in the genome. To functionally evaluate the effect of identified amino acid substitutions (AAS), we developed and implemented a bioinformatics method in a tool called PASE. The predictions of PASE, using physicochemical properties of amino acids, were consistent with other widely available homology-based tools. Our mapping strategy successfully fine-mapped the QTLs, and our bioinformatic strategies were efficient in identifying the candidate mutations and biological pathways for growth. The methods we developed could be applied to the genetic dissection of other complex traits.
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| 31. |
- Ajal, James
(författare)
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Growth and nitrogen economy of cereal-legume sole- and intercrops, and their effects on weed suppression
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Crop production currently faces the dilemma of using methods that increase crop yield but with adverse environmental effects, or attaining lower yields with less environmental impacts. Applying ecological principles has shown potential in finding a middle-ground of maintaining crop yield with less inputs. In this thesis, I evaluated the role of intra– and interspecific functional diversity of cereal–legume intercrops in increasing nitrogen accumulation efficiency, competition against weeds, and improving the productivity of the mixture compared to sole crops. Peabarley and faba bean-wheat species combinations were grown in the field in Uppsala, Sweden and Taastrup, Denmark as sole crops and two-species mixtures. In addition, a pot experiment with various combinations of faba bean, wheat, and a common weed was set up under semi-controlled conditions in Sweden. Both crops and weeds were evaluated for nitrogen economy, biomass accumulation, and grain yields. Using trait space analysis, I demonstrated that intercropping, cultivar identity, and environmental differences influence trait space through phenotypic plasticity. Furthermore, intercropping facilitated more N acquisition in the cereals compared to when grown in sole crop. For crop-weed interaction, pea-barley intercrop reduced weed biomass compared to the sole-cropped pea, and the weed species’ competitiveness and dominance was influenced by nitrogen availability in the soil. Based on the results presented in this thesis, there is need to pay more attention to the functional traits of species components when designing mixtures. The weed species composition should be taken into account before nitrogen addition, otherwise, the additional nitrogen may favour mostly weed growth, at the expense of the crops. This study is timely considering the current emphasis on crop production methods that use ecological principles to address challenges in arable farming.
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| 32. |
- Akhter, Shirin
(författare)
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Molecular mechanisms regulating early cone development in Norway spruce Picea abies (Karst)
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Flower development progress through distinct phases that are controlled by complex genetic networks, which in turn are regulated by both endogenous and exogenous factors. A large number of functional studies have been conducted over the past decades to understand the genetic networks that regulate flower development in angiosperm model species. In gymnosperms, however, the gene regulatory networks behind distinct phases of cone development are largely unknown due to the lack of functional studies. In a morphological study of early cone development in Picea abies, three distinct growth phases were defined. Transcriptome comparisons of female and vegetative buds in the three growth phases identified members of the MADS-box gene family, LEAFY-orthologs, bZIP- , AP2-, and SBP-domain proteins as being highly expressed in the different phases of female cone development. In a separate study different isoform of the MADS-box gene, DAL19 were identified. Isoforms specific expression in male, female and vegetative bud meristems provided evidence that alternative splicing may influence cone formation in a bud identity specific manner. In the early cone-setting acrocona mutant, P. abies var. acrocona, leading shoots often have needles at the base, but ovuliferous scale-like structures in the top. Hence, during shoot development, the leading shoots make a morphological shift and produce transition shoots. RNA sequencing of acrocona transition shoots demonstrated that the MADS-box genes DAL10 and DAL21, which previously have been associated with reproductive shoot identity were expressed at high levels in transition shoot meristems before the morphological shift. In addition, genes encoding FT/TFL-like, bZIP-, SOC1-like and gymnosperm specific MADS-domain proteins co-expressed with DAL10 and DAL21, suggesting at a putative role for these genes in the early development of reproductive meristems. In addition, genes encoding F-box protein and ubiquitin were expressed at high levels in late acrocona transition shoots, which possibly reflects an involvement of hormonal signalling in the acrocona transition shoot phenotype.
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| 33. |
- Aklilu, Abenezer Zeleke
(författare)
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Essays on climate policy and agriculture
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is a compilation of four papers that study energy demand, climate policy, production, and carbon sequestration within transport, agriculture and forestry. The four papers study separate topics, but have in common that they address issues that are relevant to Sustainable Development Goals. The first paper estimates the short-run and long-run price and income elasticities of gasoline and diesel demand in the EU-28 countries. The estimation method uses the ARDL bounds approach and tests the existence of a long-run relationship using data from 1978 to 2013. The study provides methodologically consistent elasticity estimates that are comparable across the EU-28 countries and allow the analysis and forecasting of the effect of a common fuel policy. Applying the estimated elasticities to an analysis of the EU’s 2030 emission and fuel consumption reduction targets shows that the current tax level does not guarantee that the target will be achieved. The second paper estimates the cost to car owners of achieving the EU’s 2050 transport sector emission reduction targets through passenger car switching from fossil fuel-driven to hybrid and electric-driven cars. Costs are calculated as decreases in consumer surplus using a dynamic optimization model. The results show that the total emission reduction cost amounts to 0.37% of the EU’s GDP, and that Germany, Italy, Spain, France, and the UK account for approximately two thirds of the total cost. Hybrid cars are cost-effective means of abatement, while electric cars are a viable means of abatement only when coupled with grid decarbonization. The third paper examines the effect of time spent collecting water for household consumption on rural agricultural production. A household-level fixed effects estimation approach is employed using three-round panel data from Ethiopia. The results show that time allocated for water collection negatively affects agricultural production by displacing productive labor. The fourth paper reviews studies in economics on the efficient design of policies for forest carbon sequestration and compares their findings with the design systems in practice. The paper shows that specific design problems are associated with the heterogeneity of landowners, uncertainty, additionality, and permanence in carbon projects. Discounting the value of the forest carbon sink, optimal contract design, and offset baseline management are recommended in the literature for the management of most design problems.
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| 34. |
- Al-Azzawi, Zaenab
(författare)
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The role of biological processes in base cation supply in boreal forest podzols
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes experiments designed to improve understanding of biological processes contributing to supply of base cations and other nutrients in boreal forest podzols. We used microcosms containing tree seedlings growing in natural substrates, a combination of direct measurements, modelling, stable Mg isotope analysis, and 13CO2 pulse-labelling. Addition of 13C-labelled fungal necromass to soil resulted in rapid decomposition and active incorporation of 13C into RNA of Burkholderia, Streptacidophilus, Dyella, Herminiimonas, Granulicella and fungal species belonging mainly to the genera Mortierella and Umbelopsis. There was no evidence of 13C incorporation into RNA of ectomycorrhizal fungi supporting the idea that ectomycorrhizal fungi primarily play an active role in organic matter decomposition by releasing N from recalcitrant substrates, but do not use organic matter as a source of metabolic C. Selected ectomycorrhizal and nonmycorrhizal fungi were examined for their capacity to fractionate and assimilate stable Mg isotopes in vitro. Ectomycorrhizal fungi mobilised and accumulated significantly higher concentrations of Mg, K and P than nonmycorrhizal fungi, when grown on granite particles. Mycorrhizal fungi were significantly depleted in heavy isotopes compared with nonmycorrhizal fungi and there was a highly significant statistical relationship between δ26Mg tissue signature and mycelial concentration of Mg. Pinus sylvestris seedlings were grown in compartmentalised microcosms allowing their mycorrhizal mycelium, but not roots, to access different substrates, including granite particles. Root biomass and contents of Ca, K, Mg, and P in plants in granite treatments were significantly higher than in control roots. Carbon allocation by the ectomycorrhizal mycelium to soil solution was significantly and positively correlated with base cation and P content of the plants. A final experiment (using reconstructed boreal forest podzol layers) was conducted in which the relative amounts of organic and mineral substrates were manipulated to simulate different levels of intensification of the removal of organic matter. All plants were deficient in K and P but had above optimal levels of Ca and Mg. Total plant and fungal mycelial biomass was positively related to the amount of organic soil in each treatment. The δ26Mg values of soil solution samples in B horizon soil increased successively with increasing plant and fungal mycelial biomass, suggesting increased uptake of Mg from the B horizon, with discrimination against the heavier isotope resulting in higher enrichment of 26Mg.
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| 35. |
- Al-Essawe, Essraa M
(författare)
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Equine seminal plasma: its role in protecting stallion spermatozoa during cryopreservation
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is considerable variability in the ability of spermatozoa from different stallions to withstand the freezing process. As a result, stallions are usually categorized as good or bad freezers. In the equine industry, the demand for frozen semen for artificial insemination is increasing, resulting in a need for optimising cryopreservation techniques. Previously the removal of seminal plasma (SP) prior to cryopreservation was shown to improve post-thaw sperm quality, whereas the effect of adding SP on spermatozoa varied among studies. Single Layer Centrifugation (SLC) is a technique that has been used to select the most robust spermatozoa from the ejaculate and prolong their viability, as well as separating them from SP. The aims of this thesis were: 1) to study the effect of combining SLC with addition of SP from stallions of known freezability on sperm cryosurvival, including their ability to bind to heterologous oocytes; 2) To explore the differences in the major protein groups in SP between the breeding and non-breeding seasons in relation to sperm quality. Selecting robust spermatozoa using SLC prior to freezing improved post-thaw sperm quality, whereas addition of pooled SP from good or bad freezers to the selected sperm samples did not have an additional beneficial effect. Sperm quality was adversely impaired after restoring pooled SP to SLC-selected spermatozoa after thawing, independently of whether the SP came from a good or a bad freezer stallion, suggesting an inability of SP to repair stallion sperm cryoinjuries in the presence of an egg yolk-containing extender. Sperm binding affinity to the zona pellucida (ZP) of bovine oocytes was reduced after adding SP from good freezer stallions prior to cryopreservation. However, when SP was added after thawing, the mean number of bound spermatozoa was higher for the group treated with SP from good freezers than for the group treated with SP from bad freezers. Minor differences in protein composition were observed between seasons as well as between good and bad freezers. In the nonbreeding season there was a higher content of heparin-binding proteins and also of a subset of non-heparin binding proteins compared to the breeding season; these proteins may be linked to fertility. Sperm quality did not decline during the non-breeding season and SP-testosterone levels did not vary between seasons. Customization of the cryopreservation protocol for individual stallions, including studying the effect of adding SP from individual stallions, would be required to optimize the effect on sperm cryosurvival. Global proteome investigation of SP proteins could help to identify cryosurvival biomarkers for stallion spermatozoa.
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| 36. |
- Al-Kass, Ziyad
(författare)
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Characterization, quantification and removal of potential pathogens from stallion semen
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In Sweden, equine artificial insemination is most frequently carried out with liquid semen rather than frozen semen. Many factors affect sperm quality during semen storage, including the presence of bacteria and addition of antibiotics. Use of Single Layer Centrifugation (SLC) or Modified SLC (MSLC) has been shown to improve sperm quality, resulting in an increase in the time for which the sperm sample retains its function during storage. These techniques can also separate spermatozoa from bacteria. The purpose of this thesis was to investigate the role of MSLC, antibiotics and bacteria on sperm quality and storage time. This thesis comprised 4 studies: Study I was a retrospective study of potential pathogenic bacteria isolated from Swedish stallion semen during the period 2007 to 2017. Study II was to identify bacteria in semen by conventional laboratory culture methods. Study III was to isolate pathogenic and nonpathogenic bacteria in stallion semen using metagenomic analysis. Study IV was to investigate the effect of MSLC and the effect of presence or absence of antibiotics in the extender on sperm quality. Our results showed that potentially pathogenic bacteria such as Taylorella equigenitalis, Klebsiella pneumoniae, beta haemolytic streptococci and Pseudomonas aeruginosa appeared infrequently in Sweden. However, many nonpathogenic bacteria were found. Metagenomic analysis enabled more bacteria to be identified than other methods. The bacterial genera identified were different between studies, animals and ejaculates, even from animals kept on the same stud. Corynebacterium spp. were the most frequently found non-pathogenic bacteria identified in all our studies. The bacterial population was decreased using MSLC, sperm quality was improved and the shelf-life of the sperm samples was increased. The presence of antibiotics in the extender did not affect sperm viability. The bacterial population was greater in samples without antibiotics than in samples with antibiotics; bacteria appeared in all samples, even those with extender containing antibiotics. There was no evidence that bacteria isolated from a stallion on one stud should also be isolated from other individuals on the same premises. More work is needed to investigate the effects of particular bacterial genera on sperm quality. In addition, it would be interesting to investigate the shape and size of bacteria in relation to spermatozoa and the proportions of different bacteria removed using MSLC. Further modifications to the SLC technique might enable the removal of more bacteria.
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| 37. |
- Al-Sarraj, Razaw
(författare)
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Analysis of factorial experiments using mixed-effects models: options for estimation, prediction and inference
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In linear mixed-effects modelling of experiments, estimation of variance components, prediction of random effects, and computation of denominator degrees of freedom associated with inference on fixed effects, are important elements of the analysis. This thesis investigates alternatives to the likelihoodbased procedures for analysis of factorial experiments with normally distributed observations. Consistent methods, such as the maximum likelihood method, can be disadvantageous in cases where only small samples are available. Moreover, the algorithms used in linear mixed-effects models can be computationally demanding in large datasets. In this thesis, Henderson’s method 3, a non-iterative variance component estimation method, was considered for estimation of the variance components in a two-way mixed linear model with three variance components. The variance component estimator corresponding to one of the random effects was improved by perturbing the standard unbiased estimator. The improved variance component estimator performed better in terms of mean square error. In an application on a quantitative trait loci (QTL) study, the modified estimator was compared to the restricted maximum likelihood estimator on data from European wild boar × domestic pig intercross. The modified estimator was shown to approximate the results obtained from the restricted maximum likelihood (REML) method very closely. For balanced and unbalanced data in two-way with and without interaction models, the generalized prediction intervals for the random effects were derived. The coverage probabilities of the proposed intervals were compared with those based on the REML method and the approximate methods of Satterthwaite (1946) and Kenward and Roger (1997). The coverage of the proposed intervals was closer to the chosen nominal level than coverage of prediction intervals based on the REML method. With focus on Type I error, the implications of the available options in the mixed procedure of SAS and the lmer function of R for the inference on the fixed effects were examined. With the default setting of SAS, the frequency of Type I error was higher than with R. The Type I error rate in SAS was close to the nominal value when negative estimates of the variance components were allowed. Both software packages occasionally produced inaccurate results.
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| 38. |
- Alam, Mehboob
(författare)
-
Microbial status of irrigation water for vegetables as affected by cultural practices : agronomic aspects
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Human pathogens present in irrigation water can be transmitted to plants. Consumption of fruits and vegetables irrigated with pathogen-contaminated water can cause illness in humans. Leafy vegetables that are consumed fresh are particularly prone to cause such illnesses. Understanding the microbiota of irrigation water and its decontamination and introducing some preventative pre-harvest cultural practices can help procure hygienically safe horticultural produce. Variations were found in water indicator organisms, including heterotrophic plate counts, total coliforms, thermotolerant coliforms, Escherichia coli and faecal enterococci, at five different sampling sites in an irrigation water distribution system (IWDS) on a commercial vegetable-growing farm. 454-pyrosequencing data showed that the IWDS bacterial community was dominated by Bacteriodetes and Proteobacteria, with classes within these phyla, including Flavobacteriia, Sphingobacteriia, α-, β- and γ-Proteobacteria, being found at all five sampling sites. The genera Arcicella, Flavobacterium, Limnohabitans, Sejongia, Fluviicola, Escherichia, Clostridium and Legionella were present at various sites. Indicator organisms and the pathogen Salmonella in the IWDS were significantly reduced by photocatalytic treatment in most cases. Pre-harvest cultural practices to reduce pathogen load, including cessation of irrigation with contaminated water three days before harvest and decreasing the water regime of the growing medium for leafy vegetables, were assessed. The results showed that an attenuated gfp-tagged E. coli O157:H7 decreased with increasing time to harvest after cessation of irrigation, but were present in the plant phyllosphere three days after cessation, irrespective of dose applied. Similarly, both attenuated gfp-tagged E. coli O157:H7 and an attenuated strain of L. monocytogenes persisted in vegetables grown at a reduced water regime in the growing medium. Total microbiota and Enterobacteriaceae remained unchanged on plants after cessation of irrigation with contaminated water and on plants grown on different water regimes. Use of contaminated irrigation water for leafy vegetable production should thus be avoided. Photocatalytic treatment can be used to decontaminate irrigation water.
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| 39. |
- Alarcon Ferrari, Cristian
(författare)
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Forests at the limits : forestry, land use and climate change from political ecology and environmental communication perspectives : the case of Chile & Sweden
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is based on a comparative study of forest use and land use for forestry in Sweden and Chile. Processes of forestry development in the two countries are placed in relation to world forestry. Theoretically, the thesis draws insights and conceptualisations from historical materialism, critical theory and world systems theory to work with a framework combining political ecology and environmental communication. The thesis deals with forestry, forest use and land use in times where the importance of wood biomass is fundamental as climate change challenges are substantially defined by the use of forests and land. In this context, the changing meanings and materiality of forests, forestry and land use constitute a fundamental political process today at both national and global levels. One main focus in the research has been to explore current processes linking forestry and climate change politics and how they are materialized in two geographical areas; the study areas having been Ñuble province in Chile and Jämtland- Västernorrland in Sweden. The thesis analyses both contemporary and past events influencing the present situation of forestry in the two countries, uses incorporated comparison as a specific comparative approach and is methodologically informed by notions of dialectics. Analysis of discourses, observations, interviews and other methods have been put together along with theoretical reasoning on the constitution and transformation of historically specific social-ecological relations. The thesis empirically shows relations between social changes associated with forestry and theoretically draws from, and elaborates on, different forms of critical theory. An important finding of this thesis is the deep interconnection between forestry in Chile and forestry in Sweden. The study also shows that forestry development in Chile influences the overall situation of forestry in Sweden and vice versa. In this regard, forestry in the two countries has been shown to form and be formed through the historical development of world forestry. The thesis also shows how climate change has transformed discursive practices of forestry in the two countries. In addition, the thesis highlights labour questions, movement of resistance related to capitalist forestry development and specific discourses articulating forestry development in the two countries. A main conclusion of the thesis is that the conflictive nature of forestry in Chile and Sweden is greatly entangled with processes of environmental communication and political ecology relations; relations that are today formed to an important degree through use value and exchange value contradictions.
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| 40. |
- Albertsson, Johannes
(författare)
-
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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| 41. |
- Ali, Alexandre Charifo
(författare)
-
Physical-mechanical properties and natural durability of lesser used wood species from Mozambique
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this study is to assess properties of lesser used/known timbers from Mozambique. The studied species were ncurri (Icuria dunensis Wieringa), ntholo (Pseudolachnostylis maprounaefolia Pax), metil (Sterculia appendiculata K. Schum), namuno (Acacia nigrescens Oliv.) and muanga (Pericopsis angolensis Meeuwen). A comprehensive literature review found the Mozambique timber sector to be dominated by very few hardwood species while the rest of 118 lesser used wood species are almost unexplored. The above mentioned lesser used timbers were selected and subjected to descriptive and comparative analyses aiming at describing the physical-mechanical properties and natural durability with regard to prospective end uses. Standard test methods determined density, moisture content, dimensional stability characteristics, colour, natural durability and a number of mechanical properties of the selected lesser used timbers. The study revealed that ntholo and ncurri are heavy timbers with a density in the range of 850-1100 kg/m3 and very low dimensional changes. Metil is a medium light wood with an average density of 550 kg/m3 at 12% moisture content and a coefficient of anisotropy of 1.8 from green to oven-dry state. End use assessments suggest that the timbers of ntholo, muanga and namuno can be used in similar applications as the well known timbers, e.g. internal joineries, tool handles and furniture. Metil timber seems suitable for packaging boxes, plywood and construction purposes. In terms of natural durability, the results showed that heartwood of namuno, muanga and ntholo can be classified as very durable to deterioration and degradation caused by fungi and termites. These timbers showed good performance when untreated samples were exposed in- and above ground field tests providing a good indication of the expected service life and outdoor use features. Wood of metil was classified as non durable to any of the considered hazards and is not recommended for exterior uses unless treated with appropriate wood preservatives. The study determined ntholo timber mechanical properties and examined interrelationships with density and anatomical features of ntholo through regression and correlation analyses. The study found ntholo to be a very dense timber with high mechanical strength in comparison to well known timbers. The regression analyses show that both ntholo sapwood and heartwood densities are poor predictors for the tested mechanical properties, although may provide some indication of tested properties. All tested properties of ntholo sapwood were influenced mainly by ground tissue proportions, while heartwood properties were described by more leveled anatomical predictors. Fiber length was the only anatomical feature significantly correlated to density and all tested mechanical properties of ntholo. The number of vessels/mm2 and % vessels were not significantly correlated to any of the measured properties but appeared to be key anatomical features for predictions under regression analysis. The integrated analysis of results from this study is expected to form a reliable background for a successful utilization of the relatively lesser explored timbers from Mozambique.
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| 42. |
- Ali, Liaqat
(författare)
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Pre-harvest factors affecting quality and shelf-life in raspberries and blackberries (Rubus spp. L.)
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fruit including berries have been demonstrated to exhibit a broad spectrum of benefits including protection against cardiovascular, neurological, and lung diseases, as well as having antioxidant, antimicrobial, anti-inflammatory, anti- diabetic and anti-aging properties. These protective effects are reported to be due to their high content of bioactive compounds, such as vitamin C, vitamin E, phenolic acids, ellagitannins, flavonoids and carotenoids. This thesis investigated the effect of pre- and postharvest factors on the concentrations of bioactive compounds in raspberries and blackberries. The factors studied included genetic variability, organic and synthetic fertilizers, seasonal variation (harvest-to-harvest and annual variation) in greenhouse, high tunnel and open field production, and post-harvest storage. Concentrations of bioactive compounds (anthocyanins, vitamin C, ellagic acid, carotenoids) in the berries, or in the leaves, were quantitatively analysed by high-performance liquid chromatography, and total phenolics were analysed by a spectrophotometric method. Generative parameters (yield, fruit size) investigated for the cultivar difference and organic nitrogen, responded differently to the nitrogen level within cultivars and varied significantly in primocane raspberries. Taste compounds, such as total acidity and different sugars, varied during the season and with nutrient regimes. Time of harvest also affected the ellagic acid content, which was high in early season, and the vitamin C content, which was high in late season in primocane raspberries. Significant changes were also found between different years. Vitamin C decreased significantly with high synthetic N and with low K application, but the application of high N with high K showed positive influence in the level of nutrients and bioactive compounds in blackberries except for ellagic acid. Increased level of organic fertilization (12-17 g N/plant) in primocane raspberries caused only minor changes in the analysed compounds. The post-harvest performance of raspberries regarding the levels of bioactive compounds was less dynamic than in blackberries. In addition, raspberries harvested in late season showed comparatively less changes in sugar content during storage as compared to early harvest, indicating less enzymatic activity in the late season.
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| 43. |
- Allen, Andrew
(författare)
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Linking movement ecology with the management of mobile species : managing moose in Sweden
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A central goal in conserving, or managing, biodiversity is to identify the spatial scale of management. Traditional approaches like protected areas aim to delineate boundaries, within which species are managed. These boundaries are set using, among others, species richness targets and political borders, but often fail to consider species movements. Subsequently, a number of challenges may arise once individuals leave demarcated areas, such as poaching or encroachment on human-dominated areas. An ongoing dilemma is that many species cannot be managed within a single area because their movements are too large, migratory birds are a classic example. These challenges point to the requirement for an improved understanding of species’ movements to not only delineate management areas, but also to identify alternative management actions that increase the scale and flexibility of management. My dissertation identifies how movement ecology may guide wildlife management. I first outline a conceptual framework that provides guidance for linking movement ecology with conservation and wildlife management. The framework is then applied through a sequence of five studies that a) provide guidance on a method that classifies and quantifies movements, b) improves our understanding of how to scale up individual movements to population patterns, c) links the movement of individuals to their reproductive performance, d) estimates population size from age-specific harvest data and e) evaluates hunting of moose in Sweden using the ecosystem exploitation hypothesis. These studies were developed using the moose (Alces alces) in Sweden, an example of a species with diverse movement patterns that is typically managed in demarcated areas like moose management areas (e.g. Sweden) or wildlife management units (e.g. Canada). In a global context, the results of my dissertation illustrate how movement ecology may guide the management of mobile species, and nationally it complements the recently adopted moose management system in Sweden. Following my research, I encourage conservationists and managers to explore new ways of strengthening the link between movement ecology and management of mobile species.
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| 44. |
- Alm, Malin
(författare)
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Welfare indicators in laying hens
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is a growing concern regarding the welfare of laying hens worldwide and there are both ethical and economic reasons for improving their welfare. Although several different welfare indicators are used today, their ability to accurately reflect welfare status is sometimes questioned. This thesis sought to increase knowledge regarding a number of these welfare indicators by investigating whether and to what extent they were affected when layers were exposed to different stressors. Three different commercial laying hen genotypes were used and birds were challenged by being excluded either from their nests in furnished cages or from the litter area in a single-tier floor system. Excluding birds from their nests resulted in an increased stress response that was detectable in corticosterone metabolites in droppings, corticosterone concentration in egg yolk, heterophil to lymphocyte ratio and egg shell irregularities. Excluding birds from the litter area during the first two weeks in the laying facility resulted in differences in feather cover, approaches towards a novel object, tonic immobility duration and egg shell irregularities measured later in the laying period. Interestingly, according to the welfare indicators used, birds previously excluded from the litter area, and consequently deprived of litter and available area, had better welfare than non-excluded birds. In addition, levels of corticosterone metabolites in droppings were influenced by factors such as diet, genotype, bird age, cage tier, droppings mass, time of day and the kind of assay used. The results showed that several, but not all, indicators were able to detect different stress responses, suggesting that they are more or less appropriate to use depending on the situation prevailing. Many factors influenced the results obtained and there were few and inconsistent correlations, displaying a complex relationship between indicators. Overall, this indicates that welfare assessment should preferably be based on results from several indicators and that careful interpretation of the results is required before stating firm conclusions regarding laying hen welfare.
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| 45. |
- Almquist, Charlotta
(författare)
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Monitoring important soil-borne plant pathogens in Swedish crop production using real-time PCR
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The global demand for food will increase considerably in the nearest future and among the major constraints to agricultural productivity are biotic stresses caused by microorganisms. In this thesis, the causal agents of four of the most important soil-borne diseases threatening the Swedish production of oilseed rape, sugar beets and red clover were selected as targets for developing diagnostic assays using real-time PCR. The disease risk assessment of clubroot in oilseed rape was improved by developing a real-time PCR assay for quantification of the causal pathogen Plasmodiophora brassicae directly in soil samples. Broad disease risk categories including a threshold level for growing resistant cultivars were established. A real-time PCR assay for quantification of Aphanomyces cochlioides, the oomycete causing root rot in sugar beets, was also developed in the present study. The potential use of this assay as a tool in disease risk assessment was demonstrated for fields with high risk of infection. Real-time PCR was used to monitor the plant- and airborne inoculum of Sclerotinia sclerotiorum, the causal fungus of Sclerotinia stem rot, in spring oilseed rape. We found that determining the presence of S. sclerotiorum on petals was not useful for stem rot risk assessment since (i) the inoculum incidence on petals varied during flowering, (ii) there was no clear relationship between petal infection and stem rot incidence and (iii) spore release and flowering were not synchronized at one of the field experimental sites. Real-time PCR detection of the incidence of S. sclerotiorum DNA on leaves revealing the field-borne inoculum and quantification of the airborne inoculum are likely more reliable tools for predicting the potential risk of disease. The pathogen complex causing red clover root rot was monitored over three years in two field experiments. Fusarium avenaceum, Phoma spp. and Cylindrocarpon destructans were detected in red clover roots early in the seeding year using real-time PCR and the levels of pathogen DNA generally increased during the following years. Significant linear relationships were found between the amount of pathogen DNA and disease severity index.
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| 46. |
- Almqvist, Viktor
(författare)
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Who you gonna call? Examining the possibilities of remote veterinary meat inspection
- 2021
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Doktorsavhandling (refereegranskat)abstract
- Demand for locally produced meat from small-scale slaughterhouses and game-handling facilities brings severe logistical challenges in meat inspection, since such facilities are often situated in rural areas and the costs and time associated with inspection visits to remote establishments are significant. With advances in technology, it might be possible to conduct meat inspections remotely via video link. This thesis aims to determine the performance of remote inspections, both ante mortem and post mortem, where a guided, untrained assistant present at the slaughterhouse relays video and sensory impressions to a veterinarian off-site. Performance was evaluated based on agreement between remote and on-site inspections. As part of this, a practical technological solution, with emphasis on a less-is-more approach, was conceived, assembled and tested in practical use. Comparisons between methods were conducted using Cohen’s kappa-based statistics. On directly comparing findings under 26 different inspection codes or classifications recorded by two veterinarians conducting inspections on 400 carcasses and organs of pigs at a Swedish large-scale slaughterhouse, it was found that the level of agreement between the two methods was generally high, with most findings scoring ‘almost perfect agreement’. When ante mortem inspections were evaluated in a similar way, it was concluded that, due to extremely low prevalence of findings, ante mortem inspections are difficult to perform remotely under current conditions. In conclusion, remote post mortem veterinary inspections appear very promising, but the method needs to be evaluated further.
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| 47. |
- Alvåsen, Karin
(författare)
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On-farm cow mortality in Swedish dairy herds
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A high rate of on-farm cow mortality (i.e. unassisted death and euthanasia) is both a financial concern and an important animal welfare issue. The overall aim of this thesis was to evaluate the development of mortality in Swedish dairy herds and to identify characteristics associated with on-farm mortality at cow and herd levels. In paper I, two analyses were performed using data from the cattle database with the objective of identifying risk factors at the herd level: one multiple-year study of 6898 herds between 2002 and 2010; and one single-year study of 4252 herds in the year 2010. Paper II is based on information from a designed questionnaire sent in 2012 to herds with either high or low mortality rates to evaluate differences in herd characteristics. In paper III, data were retrieved from the cattle database to assess hazard rates for mortality at the cow level and included cows with a calving between 1 July 2008 and 30 June 2009 (209,236 lactations). In paper IV, a field study on destruction plants was performed to assess the relative proportion of unassisted death and euthanasia. Dairy cow cadavers were examined and a hole in the forehead (caused by a bullet or a captive bolt) was used as an indication of euthanasia. Telephone interviews were carried out with the farmer to verify the type of death and to obtain a short anamnesis. The results show that the cow mortality rate has gradually increased between 2002 and 2010, from 5.1 to 6.6 deaths/100 cow-years. At the herd level, a larger herd size, longer calving intervals and the Swedish Holstein breed were associated with greater mortality. Lower mortality was observed in herds with a higher average milk yield, during autumn-winter, and in organically managed herds. In the questionnaire, the same effects of breed and herd size were identified, but also having cows on exercise pasture (instead of production pasture) during summer was associated with high mortality herds. At the cow level, the highest mortality hazards were found for traumatic events and diseases. The mortality hazard was higher in early lactation and increased with parity. Of the 433 cows in the destruction plant study, 30% had died unassisted. A high herd average stillbirth rate increased the risk of unassisted death. In conclusion, the Swedish mortality rates were found to be high from an international perspective, and several risk factors at both the cow and the herd level were identified.
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| 48. |
- Alwall Svennefelt, Catharina
(författare)
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Occupational injuries and communications in Swedish agriculture safety interventions
- 2019
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Doktorsavhandling (refereegranskat)abstract
- Systemic changes in Swedish agriculture have seen the average farm size increase, employees become more common, adoption of new technologies and an ageing farm population. This has led to many new physical and psychological health risks and the need for continued work in preventing occupational injuries. To date, education has been the main tool (in terms of total spending) used by stakeholders to influence work safety behaviour. However, this approach has been criticised by occupational safety experts for being inefficient, if not largely ineffective. It is often unclear whether the education tool itself or its implementation is the problem. Given the need to improve safety at work within agriculture and identify the mechanisms underlying intervention outcomes, this thesis explored work safety interventions in Sweden and sought to develop a deeper understanding of how motivation can be used to effect behavioural change and the underlying cognitive factors promoting or hindering these changes. Over a six-year period, four studies were carried out using mixed methods and covering topics such as occupational safety intervention implementation, outcomes, fear appeals and cognitive mediation processes. The results confirmed that there is marked under-reporting of occupational injuries in Sweden. More importantly, they showed that, despite substantial efforts to reduce occupational injuries, on taking into account the reduced labour demand in agriculture and the decline in the number of farms since 2004, the rate of occupational injuries has not significantly decreased. Fear appeals were found to be the most common motivational tool used by the largest organisations in Sweden to influence work safety behaviours. Use of an extended parallel processing model (EPPM) to describe and evaluate marketing communications revealed a mismatch between the types of threats used in communications and the behaviours promoted. Contradictory evidence was also found. On the one hand, some farmers interviewed seemed to be aware of the most common threats in their environment and nearly all had made at least some changes to their work safety environment (crediting an intervention that took place one year earlier), indicating that the intervention had worked in terms of generating awareness and stimulating adaptive behaviours. On the other hand, many of the same farmers who had made adaptive changes also showed clear signs of maladaptation. These insights can be applied to address the communication motivation and cognitive challenges in safety interventions in Swedish agriculture.
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| 49. |
- Amentae, Tadesse Kenea
(författare)
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Supply chain management approach to reduce food losses : empirical results of selected food commodities in Ethiopia
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Food loss is one of the heavy challenges to food security in low income countries. Inefficiencies and ineffectiveness of management in supply chains are considered as the major reasons for postharvest food losses. Therefore, this thesis sought to increase the knowledge base for reducing postharvest food losses using efficient and effective food supply chain management approach. The supply chain management and postharvest losses of four nationally important food commodities (milk, wheat, teff, and warqe) in Ethiopia were analysed. Teff is a cereal, while warqe is a perennial plant from which the food products kocho and bulla are extracted. Qualitative and quantitative primary data were collected using a semi-structured survey questionnaire and key informant interviews. The data were analysed using descriptive statistics, Tobit, Probit, and Structural Equation Modelling (SEM) in SPSS, AMOS, and Microsoft Excel software. Value chain analysis, questionnaire-based post-harvest loss estimations, Likert scale-based loss factor evaluations, and SEM have been applied for the analysis. The study reported significant food losses at each stage of the food supply chains. The sum of the reported estimated losses from the total marketed products along the whole chains were 14%, 16%, 39%, and 50% for dairy, teff, wheat, and warqe foods (both kocho and bulla), respectively. Poor handling practices at milk collection points, the threshing process in the teff chain, harvesting problems and bad weather conditions in the wheat chain, and poor packaging, display, and processing facilities in the kocho and bulla chains were the forefront factors causing the losses. For farmers, the Tobit model indicated the distance to the nearest market and level of production were the most important factors triggering post-harvest losses in the teff and wheat chains, respectively. The Probit analysis identified attendance in formal education as most determining for value addition decisions in the teff chain. Using the SEM, it was found that transaction costs, trust, and uncertainty significantly predicted chain actors’ supply chain governance choice (p< 0.001). On the other hand, chain actors’ supply chain governance choice significantly predicted efficiency, flexibility, and level of dairy losses at (p< 0.001) and level of integrations at (p< 0.05) in the dairy chains. The supply chain management approach was found relevant in reducing the food losses and alleviating many other problems along the food chains.
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| 50. |
- Amera sahilu, Tadesse
(författare)
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Stewardship towards responsible management of pesticides : the case of Ethiopian agriculture
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis examines pesticide use, practice and associated human health and environmental impacts in the Ethiopian Rift Valley. It uses participatory action research as a philosophy and methodology in order to understand the Ethiopian pesticide delivery system so as to bridge the gap amongst the main actors and create a space for dialogue. The pesticide delivery system in Ethiopia comprises policy makers, researchers, pesticide manufacturers, wholesalers, vendors, civil societies and farmers. These actors with divergent interests had been working in a dispersed manner with no concerted effort to mitigate the problem. Stewardship as a moral obligation to mitigate the problem was, therefore, introduced to the actors. The aim was to bring these actors together so as to initiate a system-wide pesticide users’ stewardship network that shared a sense of responsibility at all levels to bring about an ethic of reduced and responsible use of pesticides. This was first initiated by establishing a national (meta) level multiactor pesticide stewardship association which later triggered a regional (meso) level pesticide risk communication and local (micro) level action-oriented alternative pest management experimentation through farmer field schools. Combined methods of qualitative and quantitative data collection were used to explore the processes at all levels. The process revealed that the meta level network was viewed by all actors as a platform for collaborative learning and collective action driving institutional change at many levels. The meso level showed that even if the pesticide hazards were evident and different types of safe use training was provided, farmers’ risk perception continued to be low while associated hazards remained high. This was, therefore, attributed to lack of proper risk communication, which requires reframing of the approach that promotes pesticides only as a means for agriculture productivity but gives less attention to their negative impacts. The micro level showed the field-based action as a means of participatory knowledge co-production, which has been contributing to transformation towards the overarching goal of pesticide users’ stewardship. This process faced multilevel communicative, systemic, organizational and societal barriers that challenged the federal level initiative but has been well managed by the local level action, which has been a lesson for federal level actors
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