Potential in mixed swards and breeding of tall fescue (Festuca arundinacea Schreb.)

The incentives of this thesis are some of the challenges that grassland production in Belgium are exposed to. First, more dry summer spells are predicted due to climate change (IPPC, 2007). Second, more grass is cut and conserved due to current trends in dairy production. Tall fescue (Festuca arundinacea Schreb.; Fa) is a forage grass species that is expected to cope with these challenges. This thesis had three objectives: 1. to study the agronomy of Fa under Belgian conditions; 2. to develop methods that could be used in breeding to overcome the main disadvatages of Fa; 3. to breed an Fa Variety adapted to Belgian circumstances

Electrochemical alternatives to adapt the conventional procedures of surface functionalization to the local scale

International audienc

A method to search for optimal field allocations of transgenic maize in the context of co-existence

Spatially isolating genetically modified (GM) maize fields from non-GM maize fields is a robust on-farm measure to keep the adventitious presence of GM material in the harvest of neighboring fields due to cross-fertilizations below the European labeling threshold of 0.9%. However, the implementation of mandatory and rigid isolation perimeters can affect the farmers' freedom of choice to grow GM maize on their fields if neighboring farmers do not concur with their respective cropping intentions and crop plans. To minimize the presence of non-GM maize within isolation perimeters implemented around GM maize fields, a method was developed for optimally allocating GM maize to a particular set of fields. Using a Geographic Information System dataset and Monte Carlo analyses, three scenarios were tested in a maize cultivation area with a low maize share in Flanders (Belgium). It was assumed that some farmers would act in collaboration by sharing the allocation of all their arable land for the cultivation of GM maize. From the large number of possible allocations of GM maize to any field of the shared pool of arable land, the best field combinations were selected. Compared to a random allocation of GM maize, the best field combinations made it possible to reduce spatial co-existence problems, since at least two times less non-GM maize fields and their corresponding farmers occurred within the implemented isolation perimeters. In the selected field sets, the mean field size was always larger than the mean field size of the common pool of arable land. These preliminary data confirm that the optimal allocation of GM maize over the landscape might theoretically be a valuable option to facilitate the implementation of rigid isolation perimeters imposed by law.

Impurity dominated thin film growth

Magnetron sputter deposition was applied to grow thin metal films in the presence of impurities. These impurities are ambient gas molecules and/or atoms from the residual gas present in the vacuum chamber. Seven materials were investigated: four single element metals (Al, Ag, Cu, and Cr), two widely applied alloys (Cu55Ni45 and Ni90Cr10), and one high entropy alloy (CoCrCuFeNi). The thin films were analyzed using X-ray diffraction to determine the domain size, the film texture, and the lattice parameter. The same trend for all studied materials is observed. When the ratio between the impurity and metal flux towards the substrate is low, the domain size is not affected by the presence of the impurities. In this regime, the incorporation of the impurities affects the lattice parameter. At high flux ratios, the change of the domain size can be described by a power law with the exponent equal to -1/2 for all studied materials. A kinetic Monte Carlo code is used to demonstrate this observed trend

Welke grasmat voor Brussels Airport?

Op luchthavens is wild (vogels, konijnen) erg ongewenst in het kader van de veiligheid van het vliegverkeer. In de studie beschreven in dit rapport gingen we na welke grassoorten geschikt zijn voor gebruikt op luchthavens, rekening houdend met deze wildproblematiek. De voorkeur van 9 grassoorten of mengsels voor konijnen werd onderzocht in een drie jaar durende veldproef

Redox properties and reactivity of a polythiophene-modified electrode in presence of ferrocene in solution or fixed onto the polymer network

A polymer-modified electrode (PME) was tested for the examination of the electrode reactivity in presence of an electroactive specie. Ferrocene (Fc) was chosen as redox probe and cyclic voltammetry (CV) was used to investigate the redox activity of the polymer. The polythiophene matrix used can be easily post-functionalized, allowing to investigate the redox behaviour of a surface-tethered ferrocene conducting polymer compare to the redox properties of the film when the ferrocene is free in solution. Results reported show dramatic changes in voltammetric patterns obtained at \u27organic electrode\u27 compared to Pt electrode. When Fc was in solution, the current peak ascribed to Fc oxidation at PME increases promptly as the conductivity of the film switch \u27ON\u27. When Fc units were grafted onto the polymer network, the quartz crystal microbalance shows that the Fc oxidation was assisted by the conducting polymer chain

The Seebeck coefficient of sputter deposited metallic thin films : the role of process conditions

Because of their reduced dimensions and mass, thin film thermocouples are a promising candidate for embedded sensors in composite materials, especially for application in lightweight and smart structures. The sensitivity of the thin film thermocouple depends however on the process conditions during deposition. In this work, the influence of the discharge current and residual gas impurities on the Seebeck coefficient is experimentally investigated for sputter deposited copper and constantan thin films. The influence of the layer thickness on the film Seebeck coefficient is also discussed. Our observations indicate that both a decreasing discharge current or an increasing background pressure results in a growing deviation of the film Seebeck coefficient compared to its bulk value. Variations in discharge current or background pressure are linked as they both induce a variation in the ratio between the impurity flux to metal flux towards the growing film. This latter parameter is considered a quantitative measure for the background residual gas incorporation in the film and is known to act as a grain refiner. The observed results emphasize the importance of the domain size on the Seebeck coefficient of metallic thin films

Impact of the quality of organic amendments on size and composition of the weed seed bank

In addition to improving the soil quality, organic amendments of soils may affect weed seed survival, emergence, growth and reproduction. This study evaluated the effects of applications of different qualities of organic amendments on size and composition of the weed seed bank in a field under sequential cropping over 4 years. Fertilisation systems tested included farmyard manure, vegetable fruit and garden waste compost, two types of farm compost differing in carbon:nitrogen (C:N) ratio, cattle slurry and mineral fertiliser. All organically amended plots received equal amounts of C. Crop growth was equalised on all plots by applying supplemental mineral N. Seed bank sampling took place in May 2009 to a depth of 10 cm. The weed seed bank was analysed using the seedling emergence method. Despite equal crop growth in fertilised plots, total seed bank density was lowest in plots amended with compost with low C:N ratio and highest in slurry-amended plots. Observed differences in seed bank densities reflected differences in soil organic carbon content and microbial biomass. At plot level, hard-coated seeds in the seed bank (e.g. Chenopodium spp.) were inversely related to soil microbial activity. Observed differential responses of species to applied fertilisers might be attributed to interspecific differences in resistance against microbial seed degradation. Compost-based fertilisation systems could be sustainable tools for incorporation into integrated weed control strategies aiming at depleting the weed seed bank