• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 127
  • 53
  • 16
  • 15
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 250
  • 250
  • 129
  • 44
  • 43
  • 42
  • 38
  • 31
  • 30
  • 28
  • 24
  • 21
  • 21
  • 20
  • 20
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Trädstruktur i sandtallskogar i Norrbotten : Förekomst av ett urval av mykorrhizasvampar / Stand structure of sandy pine forests in Norrbotten county, Sweden : Occurrences of a selection of mycorrhiza fungi

Lindbäck, Linda January 2020 (has links)
The aim with this study was to investigate factors that affect the occurrence of mycorrhizal fungi species of nature conservation concern in sand pine forests in Norrbotten County in Sweden. In 2019, the occurrence of fruit-bodies of the species in focus was inventoried in 21 forest stands in three different areas located in three municipalities on land that SCA Skog owns and manages in Norrbotten County. The fungi included in study had been noted in the studied areas in previous inventories between the years 2013–2016, which makes it possible to compare variation in fruit body production between years. Specifically, the study tested whether mean age and diameter of trees, and base area and size of forest stands affect the occurrence of fruit bodies of the studied mycorrhiza species in the forest stands. A multiple regression analysis found a positive significant relationship between the number of species that occurred and the size and base area in the forest stands, while there was no effect of mean age and mean diameter of the trees. This indicates that it is important to consider the size and base area of forest stands to maintain mycorrhizal fungi when planning management in dry sandy pine forests. However, because fruit body production is highly variable among years further research is required to get a better understanding of how tree structure affect mycorrhizal fungi.
122

Význam mykorhizní symbiózy v invazivnosti borovice vejmutovky / Significance of mycorrhizal symbiosis in invasiveness of Pinus strobus

Antl, Tomáš January 2014 (has links)
6 Abstract This study aimed to compare the mycorrhizal fungal communities inhabiting the roots of invasive Pinus strobus L. and native Pinus sylvestris L. We also compared carbon allocation into ectomycorrhizal fungal (EcMf) and other structures of the two pine species. The aim was to assess the influence of mycorrhiza on the invasive potential of P. strobus in the protected areas of National Park Bohemian Switzerland. The two field experiments were conducted on three locations of each species. We estimated the EcM extramatrical mycelium (EMM) production by measuring the ergosterol content in sterile sand filled mesh-bags. Next measured variables were: biomass of ectomycorrhizal and saprotrophic sporocarps, fine roots biomass and leaf litter biomass to compare the one season production of each measured variables. The results revealed a major difference in EcM sporocarps production, whereas on the P. sylvestris sites was the production 100% higher. Same results came from the fine roots measurements: P. sylvestris had a higher fine roots production, which may be also related with the production of EMM, which was about 60% higher as well. The EcMf species richness on the P. strobus root-tips was as high as the native pine, but the species composition was different. The P. strobus prefers EcMf species with...
123

Reward Complementarity and Context Dependency in Multispecies Mutualist Interactions in Partridge Pea (Chamaecrista fasciculata)

Fehling, Laura Sharon 25 May 2022 (has links)
No description available.
124

Nitrogen cycling driven by soil microbial communities in exotic black locust plantations and native oak forests in the drylands of East Asia / 東アジア乾燥地の外来種ニセアカシア植林地および在来種ナラ林における土壌微生物が駆動する窒素循環

Tatsumi, Chikae 23 March 2020 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22477号 / 農博第2381号 / 新制||農||1074(附属図書館) / 学位論文||R2||N5257(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)准教授 舘野 隆之輔, 教授 北島 薫, 教授 德地 直子 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
125

An assessment of the allelopathic potential of <i>Alliaria petiolata</i>

Barto, Eulondia Kathryn 11 August 2008 (has links)
No description available.
126

Developing Production Techniques and A Site Assessment Tool for Forest Farmed Ramps in Appalachia

Aryal, Pabitra 23 June 2023 (has links)
The Allium tricoccum Aiton (ramps, aka wild leeks), a native spring ephemeral, is a cultural keystone species in Appalachia, a mountainous physiographic region encompassing 205,000 square miles of the eastern United States. People in Appalachia have long harvested ramps in the wild. However, growing demand for the plant in and outside the region has increased harvesting, resulting in threats to native populations. Agroforestry cultivation techniques and technical support for sustained-yield forest farming practices are needed to conserve ramps and meet increasing demand. Various techniques for assessing suitable production practices for ramps were explored in this dissertation, particularly examining best-suited ramp ecotypes, mycorrhizal treatment, and habitat suitability determination. In the first study, bulbs and seeds from diverse Appalachian locations were gathered and transplanted to a common experimental site to investigate the effects of different ramp ecotypes on growth, survival, and stress responses. Plant characteristics and stress measurements were recorded before transplantation and post-transplantation assessments. Specifically, the study investigated the germination rate of three ramp seed ecotypes and the growth, survival, and stress responses of eight native ramp bulb ecotypes and three commercially obtained seedling samples. Results indicated that above-ground growth, survival, and stress response on the ramp ecotypes differed significantly. The second study explored the impact of mycorrhizae on ramps and was evaluated by assessing the impact of Arbuscular Mycorrhizal Fungi (AMF) inoculation on Allium tricoccum. Four measurements, collectively referred to as parameter categories, were assessed. These included measures of 1) above-ground plant growth: leaf length, and leaf width; 2) stress measurement: transplant stress after a few days of transplant, and photosynthetic performance stress after a year of transplant; 3) survival analysis; and 4) mycorrhizal colonization rate. For each parameter category, three treatment comparison categories were conducted: 1) Positive control treatments: bulbs were planted from their native environment without treatment; 2) Negative controls: bulbs were treated with fungicide before planting to eradicate existing AMF in roots; and 3) The test group: bulbs were inoculated with commercial AMF (Atriva 500). Results indicated that mycorrhizal inoculation could increase ramp leaf length (P≤0.03). However, the impact varied by ecotype, highlighting the importance of considering local environmental conditions and ramp ecotype. Mycorrhizal inoculation did not impact ramp growth at the seedling stage. Mycorrhizal treatment increased the transplanted ramp's survival and stress tolerance (P≤0.001). The third study used multi-criteria decision-making (MCDM), the Analytic Hierarchical Process (AHP), and weighted linear combinations to model suitable habitats for ramps production. Ten habitat criteria were chosen (including five soil properties, three topographic parameters, and two land use properties) to assess the potential for growing ramps in seven counties in Virginia, West Virginia, Pennsylvania, and North Carolina. The percentage of highly suitable areas for ramps production in the studied counties ranges from 21.5% in Haywood County to 49.6% in Macon County. Similarly, moderately suitable areas range from 36.7% in Macon County to 54.5% in Lawrence County. Ground truthing was performed to validate the model. Ramp patch locations within each county were geocoded in the final suitability maps. Existing ramp patches were within the model's estimate of moderate to high site suitability ranges, suggesting the model is valid. Results of the study suggest that site suitability modeling could be useful for producers interested in growing ramps in forest farm settings across Appalachia. / Doctor of Philosophy / The ramp, also known as the wild leek, is an important food, medicinal and cultural resource for the people of Appalachia. However, increasing demand for ramps beyond this region has led to over-harvesting and threatens the plant's native populations. Appropriate cultivation techniques and technical support for sustained-yield forest farming practices are needed to conserve ramps and meet growing demand. This dissertation explores various techniques for assessing suitable production practices for ramps, including examining ramp ecotypes, mycorrhizal treatments, and habitat suitability determination. The first study evaluated the ecotypic variation among ramps collected from different geographic regions and their impact on plant performance. Ramp ecotypes displayed differences in above-ground growth, survival, and stress response. The second study examined the impact of mycorrhizae on ramps and found that mycorrhizal inoculation can increase ramp leaf length and survival and stress tolerance of transplanted ramps. However, this impact varied by ecotype, highlighting the importance of considering local environmental conditions and ramp ecotype. The third study involved developing a model to identify suitable habitats for growing ramps. The model was tested for seven counties across Virginia, West Virginia, Pennsylvania, and North Carolina. The percentage of land predicted as highly suitable for ramps production ranged from 21.5% in Haywood County, NC, to 49.6% in Macon County, NC. Moderately suitable lands ranged from 36.7% in Macon County, NC to 54.5% in Lawrence County, PA. Ground truthing confirmed the model's accuracy as geocoded existing ramp patch locations fell within the estimated suitable ranges. Site suitability modeling could be useful for people interested in growing ramps in forest farm settings across Appalachia. Overall, this research provides insights into best practices for ramp cultivation that help conserve a cultural keystone species and meet the growing demand for ramps.
127

Isolation, propagation and rapid molecular detection of the Kalahari truffle, a mycorrhizal fungus occurring in South Africa

Adeleke, Rasheed Adegbola 03 April 2013 (has links)
Terfezia pfeilii is an edible mycorrhizal fungus that thrives in the Kalahari Desert of southern Africa. It is best known by desert dwellers for its flavour and as a source of nutrition. Although the genus Terfezia is generally regarded as being an ectomycorrhizal mycobiont, the exact mycorrhizal type formed by T. pfeilli and its' associated host plants remains uncertain. Discovery of the host plants for T. pfeilii would first be required in order to further investigate the life cycle and cultivation of this truffle. This study focussed on the isolation of mycelia from the ascocarp, optimising the growth conditions of the mycelial cultures, rapid molecular identification of T. pfeilii, investigation of potential helper bacteria and mycorrhizal synthesis experiments. T. pfeilii ascocarps were harvested from the Spitskop Nature Reserve in Upington, South Africa. Ascocarps were successfully identified using both morphological and molecular methods. Despite the delayed growth mostly caused by contaminating microorganisms, the isolation of T. pfeilii mycelia culture was successful. Molecular techniques were used to confirm the identity of the pure culture. Further studies were conducted on ways to improve the growth conditions of the mycelial culture on Fontana medium. An optimum temperature of 32°C, the addition of Bovine Serum Albumin as a nitrogen source and a pH of 7.5 significantly improved the growth of T. pfeilii in vitro. A rapid PeR-based molecular method was developed to speed up the identification of T. pfeilii. Specific primers that can exclusively amplify the ITS region of T. pfeilii were designed and used to identify both the ascocarps and the mycelial culture. The specificity of these primers was confirmed by their inability to amplify DNA from the isolates of contamining fungi obtained during the isolation process. Molecular comparison was made to confirm the reclassification of South African samples of T. pfeilii as Kalaharituber pfeilii as proposed by Ferdman et al.,(2005). However, in this study, the name T. pfeilii has been retained. A total of 17 bacterial isolates were obtained from the fruiting bodies of T. pfeaii and these were tested for stimulation of mycelial growth in vitro, indole production and phosphate solubilising capabilities. Bacterial isolates that showed potential to be Mycorrhization Helper Bacteria (MHB) were identified as Paenibacillus sp., Bacillus sp. and Rhizobium tropici. Selected plant seedlings were inoculated with T. pfeilii cultures or ascocarp slurry in order to re-establish the mycorrhizal association. After 8 months, light microscopy observations revealed an endomycorrhizal type association between Cynodon dactylon and T. pfeilii. This was confirmed with molecular analysis using specific T. pfeilii ITS primers. After 15 months, molecular methods confirmed Acacia erioloba as another host plant. These results have provided essential information paving the way for further investigation into the life cycle and biology of the Kalahari truffle. / KMBT_363 / Adobe Acrobat 9.53 Paper Capture Plug-in
128

The role of indigenously-associated abuscular mycorrhizal fungi as biofertilisers and biological disease-control agents in subsistence cultivation of morogo / Mohlapa Junior Sekoele

Sekoele, Mohlapa Junior January 2006 (has links)
The study examined interactions between morogo plants, arbuscular mycorrhizal fungi (AMF) and Fusarium species. Morogo refers to traditional leafy vegetables that, together with maize porridge, are dominant staple foods in rural areas of the Limpopo Province such as the Dikgale Demographic Surveillance Site (DDSS). Morogo plants grow either as weeds (often among maize), occur naturally in the field or are cultivated as subsistence crops by rural communities. Botanical species of morogo plants consumed in the DDSS were determined. Colonisation of morogo plant roots by AMF and Fusarium species composition in the immediate soil environment were investigated in four of eight DDSS subsistence communities, Isolated AMF were shown to belong to the genera Acaulospora and Glomus. Twelve Fusarium species were isolated from soil among which Fusariurn verticilliodes and Fusarium proliferaturn occurred predominantly. Greenhouse pot trials were conducted to examine the effect of AMF on morogo plant growth (cowpea; Mgna unguiculata) and Fusarium proliferatum levels in soil, Interaction between plants and AMF, as well as tripartite interactions of cowpea plants, AMF and Fusarium proliferatum were investigated. Non-inoculated cowpea plants served as controls for the following inoculations of cowpea in pots: (i) Fusarium proliferatum; (ii) commercial AMF from Mycoroot (PTY) Ltd. (a mixture of selected indigenous Glomus spp referred to commercial AMF for the purpose of this study); (iii) indigenous AMF obtained from DDSS soil (referred to iocal AMF for the purpose of this study); (iv) commercial AMF plus Fusarium proliferatum; (v) local AMF plus Fusariurn proliferatum. Results showed reduced root colonization by local as well as commercial AMF when Fusarium proliferatum were present. Local AMF significantly enhanced cowpea growth while commercial AMF apparently reduced the level of Fusarium proliferatum in the rhizosphere and surrounding soil. Results suggest that AMF may have potential as biological growth enhancers and bioprotective agents against Fusarium proliferatum. / Thesis (M. Environmental Science (Water Science))--North-West University, Potchefstroom Campus, 2007.
129

Protection du blé contre l'oïdium par des champignons mycorhiziens à arbuscules : mécanismes et optimisation / Wheat protection against powdery mildew by arbuscular mycorrhizal fungi : mechanisms and optimization

Mustafa, Ghalia 10 September 2015 (has links)
L'utilisation des champignons mycorhiziens à arbuscules (CMA) pourrait constituer une alternative potentielle aux traitements fongicides conventionnels pour lutter contre les maladies cryptogamiques des plantes. Notre travail a consisté à étudier l'éventuel effet protecteur de la mycorhization arbusculaire chez le blé tendre (triticum aestivum L.) contre Blumeria graminis f. sp. tritici (Bgt), un champignon biotrophe responsable de l'oïdium, une maladie affectant les parties aériennes de la plante. L'inoculation mycorhizienne du blé avec le CMA Funneliformis mosseae (FM), en conditions controlées et optimisées, nous a permis d'obtenir parallèlement à un taux de mycorhization de 38% des plants de blé, une amélioration significative de la biomasse et un taux de protection contre Bgt estimé à 78%. Ces résultats suggèrent l'induction d'une résistance systémique des réactions de défense du blé par mycorhization (Mycorrhiza-Induced Resistance, MIR). Cette protection serait liée à une accumulation de composés phénoliques et de preoxyde d'hydrogène dans les cellules épidermiques des feuilles de blé mycorhizé, au niveau du site de pénétration de Bgt. Une surexpression des gènes POX, PAL, CH11 et NPR1 codant pour des marqueurs de défense a également été mise en évidence dans les feuilles en absence d'infection par Bgt. Enfin, nos travaux ont également souligné l'intégration de divers paramètres pour optimiser l'utilisation des CMA comme agents de biocontrôle chez le blé. La meilleure protection contre l'oïdium a été obtenue aec un apport en phosphore réduit de 5 fois par rapport à celui préconisé au champ et un inoculum mycorhizien à base de Fm, que ce soit chez un cultivar modérément sensible ou un cultivar plus résistant. / The use of arbuscular mycorrhizal fungi (AMF) could be an innovative alternative to chemicals against fungal plant diseases. Our work aimed at studying the possible protective effect of arbuscular mycorrhization in the bread wheat (Triticum aestivum L.) against Blumeria graminis f. sp. tritici (Bgt), a biotrophic fungi responsible of wheat powdery mildew, a disease affecting the aerial plant organs. Wheat mycorrhizal inoculation by Funneliformis mosseae (Fm), under controlled and optimized conditions, allowed us to obtain concomitantly a micorrhizal rate of 38%, a significant increase of plant biomass and a protection level against Bgt estimated at 78%. These results suggest the induction of systemic wheat defense reactions resulting from mycorrhization (Mycorrhiza-Induced Resistance - MIR). This protection is linked to an accumulation of phenolic compounds and hydrogen peroxide at the Bgt penetration sites in epidermal leaf cells of mycorrhized wheat plants. Up-regulations of POX, PAL, NPR1 and CH11 genes encoding for defense markers were also pointed out in leaves of mycorrhizal wheat in the absence of Bgt infection. Moreover, our study highlighted the importance of taking into account various parameters to optimize the use of AMF as biocontrol agents. The highest protection against powdery mildew was obtained with a 5-fold reduced phosphorus input compared to that recommended in the field and with the mycorrhizal inoculum Fm, in both a moderately susceptible or a more resistant cultuva
130

A composição da comunidade bacteriana do solo como fator determinante na micorrização de cana-de-açúcar por Glomus clarum / The bacterial community composition of soil as a factor in mycorrhizal sugarcane by Glomus clarum

Andrade, Pedro Avelino Maia de 19 June 2013 (has links)
A cana-de-açúcar é uma das principais culturas do sistema agrícola brasileiro, e apresenta-se atualmente em plena expansão. Porém o uso do solo e a implementação de diferentes tecnologias de manejo têm originado alterações no equilíbrio ambiental, onde importantes interações microbianas ocorrem de forma essencial para o desenvolvimento vegetal. Dentre a vasta diversidade de microrganismos do solo, destacam-se os fungos micorrízicos, organismos intimamente associados as raízes das plantas, auxiliando a mesma, dentre outras formas, na obtenção de água e nutrientes. Estes fungos, no entanto, interagem também com outros organismos do solo, como por exemplo, com a comunidade bacteriana presente neste ambiente. Desta forma, o presente trabalho buscou estudar a dinâmica de interação entre cana-de-açúcar e o fungo micorrízico arbuscular (FMA) G.clarum em solos com diferentes composições da comunidade bacteriana. A metodologia utilizada foi a \'diluição para extinção\', onde diluições seriadas (10-1; 10-3; 10-6 e 10-9) de um solo natural foram usadas para inocular o solo estéril. Sobre esta base, foi monitorada pelo período de 60 dias, a colonização da planta pelo FMA e a estruturação das comunidades bacterianas. Como resultado, foi observada uma maior colonização das raízes de cana-de-açúcar para os tratamentos inoculada com menores diluições da comunidade original (solo natural e diluições 10-1 e 10-3), sendo da mesma forma observada uma distinção entre as comunidades bacterianas destes tratamentos para os demais. Estabelecendo correlações entre os grupos microbianos e as taxas de colonização micorrízica, foi possível nomear, com base no sequenciamento massivo da região V6 do gene ribossomal 16S DNAr, a alteração conjunta da micorrização com mudanças nos grupos de Actinobacteria,Bacteriodetes,Firmicutes,Proteobacteria,Verrucomicrobiae Acidobacteria. Concluindo, este trabalho demonstra a dependência que um processo importante, como a micorrização, possui da comunidade bacteriana do solo, e indica que em áreas degradadas, com menores níveis de diversidade bacteriana, tal processo pode ocorrer com menor eficiência. / Sugarcane is an important Brazilian agricultural system crop and presents currently booming. Nevertheless, land use, and implementation of different management technologies have originated changes in environmental balance, where important microbial interactions occur as essential for plant development. Among the wide diversity of soil microorganisms, the mycorrhizal fungi is highilighted as organisms closely associated with plant roots, helping plants, in any way, to obtain water and nutrients. These fungi however, also interact with other soil organisms, such as for example, bacterial community in these environments. Thus, the present work aimed to study the dynamics of interaction between sugarcane and arbuscularmycorrhizal fungi (AMF) Glomusclarum in soils with different compositions of the bacterial community. The methodology used was \"dilution to extinction\", where serial dilutions (10-1, 10-3, 10-6 and 10-9) of a natural soil were used to inoculate a sterile soil. On this basis, were monitored along a period of 60 days, plant colonization by AMF, and structure of bacterial communities. As a result, we observed a higher colonization of roots of cane sugar for treatments inoculated with lower dilutions of the original community (natural soil and dilutions 10-1 and 10-3), and likewise observed a distinction between these bacterial communities treatments to others. Establishing correlations between microbial groups with observed rates of colonization, it was possible to name, based on the massive sequencing of the region V6 ribosomal gene 16S rDNA, the joint amendment of mycorrhiza with changes in groups of Actinobacteria; Bacteriodetes; Firmicutes, Proteobacteria; Verrucomicrobia and Acidobacteria. In conclusion, this work demonstrates the dependence of an important process, as the AMF, has tosoil bacterial community, and indicates that degraded areas, with lower levels of bacterial diversity, such a process can occur with lower efficiency.

Page generated in 0.0936 seconds