Thesis (MTech (Horticulture Science))--Cape Peninsula University of Technology, 2009 / The study used common bean (P. vulgaris L. variety Provider) in a spilt-split-plot design involving 2 levels of Rhizobium inoculation (with and without rhizobia), 3 levels of lime (0, 2 and 3 t.ha-1) and 3 levels of molybdenum (0, 6 and 12 g.kg-1 of seeds) in a glasshouse experiment. The glasshouse experiment was then verified in the field during 2008 and 2009 cropping seasons. The aim was to assess the effects of Rhizobium inoculation, molybdenum and lime supply on: i) yield and yield components of the P. vulgaris L. ii) Changes in soil pH and the concentrations of selected plant-available nutrients in the rhizosphere, iii) photosynthesis and chlorophyll formation in P. vulgaris L. and (iv) plant growth and N2-fixation in P. vulgaris L. The results showed that Rhizobium inoculation had significant effects in increasing yield components and ultimately the final seed yield. Rhizobial inoculation also significantly increased the levels of chlorophyll content in leaves, improved all photosynthetic parameters, increased dry matter yield of different organs and decreased 15N values in all organs assessed. As a result, % nitrogen derived from atmosphere (%Ndfa) in all organs as well as the amount of N derived from fixation was improved. In the field, the whole plant level of N-fixation of P. vulgaris L. from Rhizobium inoculation accounted for approximately 33 kg N.ha-1. Furthermore, soil pH and the concentration of mineral nutrients (P, K, Ca, Mg, Na, Fe, Cu, Zn and Mn) in the rhizosphere were significantly increased with Rhizobium inoculation when compared with the control.

No description available.

No description available.

The effects of 6/85-strain M. gallisepticum (6/85MG) inoculation alone or in conjunction with a F-strain M. gallisepticum (FMG) over-lay and its timing on the performance, egg, blood, and visceral characteristics of commercial egg laying hens were investigated. The applied treatments did not affect layer performance, but did affect yolk moisture and fatty acids, liver moisture, and plasma protein. The plasma protein and liver moisture changes may be indicative of the effects of the treatments on the hydration statuses of the birds during lay, whereas alterations in yolk palmitic, oleic, and linolenic acid levels with treatment may have been manifested by disturbances in the desaturation and elongation processes of fatty acid synthesis. Pre-lay 6/85MG inoculations may be a suitable substitute for pre-lay FMG inoculations and FMG overlays during lay on pre-lay 6/85MG inoculations may provide continual protection without eliciting any subsequent suppressive affects on performance.

L’objectif de ce travail consiste à améliorer les propriétés mécaniques d’un acier faiblement allié à bas carbone (0,2%) sans recours à des procédés de métallurgie secondaire onéreux. Pour cela, un processus d’inoculation, déjà utilisé lors de l’élaboration des fontes, est transposé à notre nuance d’acier. Il consiste à ajouter des éléments en très faible quantité dans l’acier liquide pour en modifier le processus de solidification donc la microstructure et par conséquent les propriétés de l’acier, dont la résilience. L’ajout d’éléments en très faible quantité ne modifie pas la nuance d’acier. Ils doivent être ajoutés en fin de fusion du métal sous forme de poudre dans le jet de coulée. Les effets de ces éléments se verront sur la microstructure notamment au niveau des inclusions et de la taille des grains. Le « bon candidat » est un élément qui conduira à une répartition homogène d’inclusions de petites tailles et de forme sphérique. Il doit aussi permettre de réduire la taille des grains. Ces modifications de structure sont supposées améliorer les propriétés mécaniques de l’acier et notamment la résistance aux chocs. Une pièce de référence est réalisée pour pouvoir en étudier la microstructure. La forme retenue est un lingot parallélépipédique dimensionné à l’aide d’un logiciel de simulation de coulée afin de prévenir des principaux défauts de fonderie. La taille est adaptée à l’échelle laboratoire (capacité four 120 kg). Les charges de fusion correspondant à la nuance étudiée sont fournies par l’entreprise partenaire de la thèse, SAFE Metal. La première étape est d’obtenir un bain convenablement désoxydé ; c’est-à-dire ajouter de l’aluminium afin de piéger l’oxygène dissous pour l’évacuer. Pour mettre en évidence d’éventuels effets significatifs des différents inoculants testés, il faut partir d’un échantillon de référence contenant un nombre d’inclusions relativement élevé. Ceci est obtenu en ajoutant du soufre dans le bain liquide. Cet élément agit directement sur le nombre d’inclusions présentes dans l’acier en formant des sulfures. Pour passer à l’étape d’inoculation il a fallu créer un outillage spécifique pouvant s’adapter à l’échelle du laboratoire. Des essais sont ensuite réalisés avec différents produits à des concentrations variables. Les échantillons obtenus sont analysés par différentes techniques : analyse chimique de l’acier (spectrométrie étincelle et ICP), analyse de microstructure et de la taille de grains (par micrographie optique) et le comptage inclusionnaire. En ce qui concerne ce dernier point qui consiste à détecter les inclusions, à les compter et à les classer par leur nature, leur forme et leur taille, deux possibilités existent. Soit à l’aide d’un microscope optique mais les risques d’erreur sont importants et le processus est long et fastidieux, soit à l’aide d’un logiciel spécifique (AZtec) couplé à un microscope électronique à balayage (MEB). C’est ce choix qui a été fait, car outre le fait qu’il permette un gain de temps considérable grâce à une automatisation du processus, il est possible de connaître via une sonde EDS, la composition chimique de chaque particule. Pour tous les produits testés, il a été montré que l’inoculation n’avait que peu d’effet sur la taille des inclusions et qu’elles deviennent plus complexes en contenant plusieurs éléments chimiques. Pour certains produits, on voit apparaître des amas d’inclusions. Ces amas sont susceptibles de favoriser la fragilité de l’acier en formant des amorces de fissuration. Pour d’autres, les inclusions diminuent nettement, ont une forme globulaire et la taille des grains est affinée. Ces effets ont tendance à améliorer les propriétés mécaniques de ces aciers. La teneur d’introduction de l’inoculant est aussi déterminée pour un maximum d’efficacité. L’inoculant le plus important pourra être utilisé pour une possible industrialisation. / The objective of this work is to improve the mechanical properties of a low-carbon steel (0.2%) without the use of expensive secondary metallurgy processes. For this, a method of inoculation, already used during the development of the cast iron, is transposed to our steel grade. It consists in adding very small quantities in liquid steel in order to modify the solidification process, thus the microstructure and consequently the properties of the steel, especially resilience. The addition of elements in very small quantities does not modify the grade of steel. They must be added at the end of melting of the metal in the form of powder in the casting stream. The effects of these elements will be seen on the microstructure, particularly in terms of inclusions and grain size. The "good candidate" is an element that will lead to a homogeneous distribution of inclusions of small size and spherical shape. It must also make it possible to reduce the size of the grains. These structural modifications are supposed to improve the mechanical properties of the steel and in particular the impact resistance. A reference piece is made to study the microstructure. The retained shape is a parallelepiped ingot sized using a casting simulation software to prevent major foundry defects. The size is adapted to the laboratory scale (furnace capacity 120 kg). The load corresponding to the grade studied are provided by the SAFE Metal, the partner company. The first step is to obtain a suitably deoxidized bath; that means adding aluminum in order to trap the dissolved oxygen and to evacuate it. To demonstrate any significant effects of the various inoculants tested, it is necessary to start from a reference sample containing a relatively high number of inclusions. This is achieved by adding sulfur to the liquid bath. This element acts directly on the number of inclusions present in the steel by forming sulphides. For the inoculation stage, it was necessary to create specific tools that could be adapted to the laboratory scale. Trials are then carried out with different products at varying concentrations. The samples obtained are analyzed by various techniques: chemical analysis of steel (spark spectrometry and ICP), microstructure and grain size analysis (optical micrograph) and inclusion counting. In order to detect inclusions, count and classify them by their nature, shape and size, two possibilities exist. Either using an optical microscope but the risks of error are significant and the process is long and tedious, either using a specific software (AZtec) coupled to a scanning electron microscope (SEM). It is this choice that was made, because besides the fact that it allows a considerable saving of time thanks to an automation of the process, it is possible to know via an EDS probe, the chemical composition of each particle. For all the products tested, it was shown that inoculation had little effect on the size of the inclusions and that they became more complex by containing several chemical elements. For some products, clusters of inclusions appear. These clusters are likely to promote the fragility of steel by forming cracking primers. For others, the inclusions decrease sharply, have a globular shape and the grain size is refined. These effects tend to improve the mechanical properties of these steels. The introductory content of the inoculant is also determined for maximum effectiveness. The most efficient inoculant can be used for a possible industrialization.

Les alliages Ti-Al sont depuis peu utilisés industriellement dans le domaine aéronautique. Il est nécessaire d’affiner les grains dans ces alliages en évitant la formation des précipités. Une nouvelle méthode d’inoculation appelée inoculation isomorphe a été développée où les particules agissent comme des sites de croissance plutôt que comme des sites de germination, évitant ainsi la barrière d’énergie pour la germination. Trois alliages inoculants ont été développés, les deux premiers, Ti-10Al-25Nb et Ti-25Al-10Ta, allient une bonne cohérence du paramètre de maille avec l’alliage de base et une bonne stabilité dans le liquide. Le troisième, Ti-47Ta, met en avant l’aspect stabilité. Les coulées ont montré que les premiers deux alliages ont affiné les grains sans laisser de particules hétérogènes. L’alliage binaire Ti-Ta a une densité trop importante et les particules ont sédimentées dans le lingot où elles n’ont pas pu jouer leur rôle. L’efficacité des inoculants est supérieure à l’unité, chaque particule étant responsable de la formation de plus d’un nouveau grain. Ce dernier effet est attribué à la polycristallinité des inoculants qui peuvent se fragmenter par dissolution préférentielle aux joints de grains. Les calculs prenant en compte la fragmentation et la dissolution indiquent des efficacités proches de l’unité, ce qui confirme les valeurs expérimentales d’efficacité anormalement élevées / Ti-Al alloys are an important material for aerospace applications. In order to implement them in more applications it is important to develop a method of grain refinement which can avoid precipitates. A new method of inoculation called isomorphic inoculation was developed where inoculant particles act as direct centers of growth rather than nucleation sites, avoiding the energy barrier required for nucleation. Three inoculant alloys were tested, two which balanced lattice matching between the inoculant and bulk alloy and the inoculant stability in the liquid melt, Ti-10Al-25Nb and Ti-25Al-10Ta, and one which prioritized stability, Ti-47Ta. Casting trials were carried out which showed the balanced alloys sucessfully grain refined the as-cast structure without leaving any heterogeneous particles in the structure. The binary Ti-Ta alloy was not successful due to its high density which caused the particles to settle to the bottom of the ingots where they could not participate in solidification. The inoculants were found to have an efficiency greater than one, meaning each particle was responsible for more than one new grain forming in the cast structure. This was attributed to the polycrystalline nature of the partciles which may break up into multiple particles by preferential dissolution or wetting of the grain boundaries during interaction with the melt. Calculations showed that taking into account particle break up and dissolution the efficiencies approached one, indicating this mechanism is responsible for the anomalously high efficiencies observed

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Mycorrhizae improve plant growth and ecosystem sustainability by forming a symbiotic association with higher plants including the economically important willows (Salix spp.). With the recognition of the importance of mycorrhizae in terrestrial ecosystems, inoculation of plants with mycorrhizae is becoming a common practice in agricultural and land reclamation industries. However, little information is available on important ecological parameters such as soil aggregation, soil organic carbon content (SOC) and mycorrhizal communities associated with willow rhizospheres in response to mycorrhizal inoculation in willow systems. The main objectives of this research were to explore how commercial mycorrhizal inoculation of willows impacts (1) percent water-stable soil aggregates (%WSA); (2) indigenous arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (EMF) community composition associated with different size soil aggregates; (3) SOC, and (4) willow growth. These objectives were examined under both greenhouse and field conditions. Using molecular approaches, we observed the existence of spatial variability in indigenous AMF communities among different soil aggregate size classes. This spatial variability varied with type of soil and could be reduced by inoculating with a commercial AMF inoculant. The indigenous EMF diversity was low and did not show spatial heterogeneity among soil aggregates, but it did vary with soil type. In addition, other parameters, including %WSA, SOC within the willow rhizosphere, and willow plant growth also varied by soil type and changed in association with commercial mycorrhizal inoculation. In the field experiment, soil extracts from willow nursery soil had comparable plant growth promotion with commercial mycorrhizal inoculation, and altered the AMF community associated with bulk soil and soil aggregates in the willow rhizosphere. These results suggest that historically superior willow growth in the willow nursery soil could be due to pre-existing soil microbiological factors. Overall this research indicates that AMF and EMF inoculation has the potential to influence the composition of the AMF community, but had little influence on the composition of the EMF community in the systems tested. / Natural Sciences and Engineering Research Council of Canada

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1990. / Includes bibliographical references (leaves 164-173) / Microfiche. / xi, 173 leaves, bound ill. 29 cm

The primary aim of this study was to investigate the effects of seed inoculation with the biocontrol agent Pseudomonas fluorescens strain F113 (producing the antibiotic DAPG) and its modified derivative strain F113G22 (with DAPG production disrupted) on the uptake of nitrogen by pea and wheat plants. Uptake of N by the two plant species was investigated in soil microcosms amended with 15N-labelled fertilisers (urea or ammonium nitrate) or 15N-labelled plant residues. Uptake of fertiliser-N was unaffected by inoculation. However, uptake of N derived from organic residues was enhanced in pea inoculated with either strain. In contrast, uptake of N by wheat was reduced in the presence of either strain F113 or F113G22, suggesting that the effects of these microbial inocula on N-mineralisation in the rhizosphere were dependent on plant species. It was subsequently found that microfaunal populations, especially soil nematodes in the rhizosphere of inoculated pea were significantly larger than those associated with the rhizosphere of non-inoculated controls. In wheat, however, microfaunal populations in the rhizosphere of inoculated plants were lower than those associated with noninoculated controls. These trends were repeated using simple sand microcosms into which soil bacteria and the bacterial-feeding nematode Caenorhabditis elegans were introduced. This suggested that effects on N-mineralisation were mediated by changes in populations of microbial-feeding microfauna. As a possible explanation for the increased nematode populations in the rhizosphere of inoculated pea plants, the nematicidal effects of pea seed exudates on C. elegans were investigated in small-scale sand systems. It was found that exposure to non-inoculated pea seeds reduced the short-term survival of C. elegans as compared to unamended sand, and that survival was greater in the presence of pea seeds inoculated with either strain than non-inoculated seeds, suggesting that nematicidal compounds released by germinating pea seeds were utilised by the P.fluorescens strains. No such effects were observed for wheat.