Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1964. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 24.

Thesis (M.S.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Fabian D. Menalled. Includes bibliographical references.

Th. doct.-ing--Nancy, I.N.P.L., 1983.

Crop rotation is a key strategy of sustainable agriculture in the Canadian Prairie. Improving crop productivity and yield stability in pulses-based cropping systems with better soil biology is the ultimate goal of this research. Firstly, my studies provide information on the effect of pulses on the biodiversity of soil fungi: arbuscular mycorrhizal fungi (AM) and non-AM fungi, associated with the main pulse species grown in the Canadian Prairie (field pea, lentil, and chickpea), and their influence on wheat-based cropping systems. Secondly, the optimum 4-yr crop rotation for wheat production was determined, based on the relationship among fungal communities associated to the different crops and the yield and quality of these crops. My research included two experiments. First, in a field experiment replicated in time and site, the effect of previous pulse crops on wheat root-associated microbial communities and crop performance was assessed in four 2-yr rotation systems. Second, a 4-yr field experiment evaluated the relative influence of eight different crop rotations on root-associated microbial communities and on wheat productivity in the last year of the rotations. A greenhouse assay was conducted to evaluate, under controlled conditions, the influence of the microbial communities selected by these previous field crop rotations on wheat performance, using soil from the field as inoculant. The response of root-associated microbial communities was characterized using next generation sequencing technologies, phospholipid fatty acid markers, microscopic observation of roots and soil dehydrogenase assay. Plant response was evaluated based on crop density, biomass, yield and tissue nutrient content. My studies showed that community composition of AM and non-AM fungal communities in the roots of wheat were largely influenced by host plant identity and environmental conditions. The structure of the overall fungal community in wheat roots was not affected by the previous crops. The soil microbial legacies of previous crops were different from the fungal communities found in the roots of the following wheat, suggesting that wheat, as a host plant, selects and associates with a specific fungal community. Seasonal variations in soil moisture, temperature, pH, and nutrient cycling between sampling times have a great influence on soil microbes and could also be influencing these effects. The 2-yr crop rotation experiment revealed that wheat after a pulse crop had higher plant density and produced more seed biomass and total yield. The 4-yr crop rotation studies revealed that, in the field, diversified rotations including pea or lentil in alternate years, largely contributed to wheat performance. However, rotations including chickpea contributed little to the rotation benefits, suggesting that a careful selection of plant species is essential to improve the performance of the agroecosystem. Contrary to the field results’ findings, under greenhouse conditions, rotations that included chickpea before wheat contributed the best to wheat productivity, suggesting that in the field, factors other than the microbial community selected by chickpea were responsible for the poor performance of chickpea-wheat rotations in the field. Soil bacterial and fungal biomasses were positively correlated with wheat yield in the field experiments, which suggests that an abundant and diversified microbial community positively influences wheat productivity. Also, possible antagonistic and synergistic interactions between different AM species and root pathogens could be inferred. These results suggest that many AM fungi can potentially contribute to combat pathogens and enhance plant performance, whereas other might produce detrimental effects on the plants. Overall my studies revealed that host plant identity and environmental conditions influence the fungal community structure and dynamics. The frequency and sequence of crops in the rotations strongly influences productivity in wheat based agroecosystems. Lentil and pea alternating with wheat largely contribute to wheat performance. Thus, the productivity of wheat can be improved by selecting and including the plant species most beneficial to the rotation in order to increase soil available water and N, while promoting beneficial microbial associations and reducing disease incidence.

TITLE: Canola Production as Influenced by Previous Crop and Tillage System MAJOR PROFESSORS: Dr. Michael Schmidt and Dr. Brian Klubek This study was conducted to compare the profitability of winter canola versus winter wheat following corn and soybean under a reduced till and no till regime. Yield of double crop soybean production behind canola vs. wheat was also studied. The experiment was designed as a complete factorial with a split-split-split plot arrangement using 4 replications. Corn/soybean served as the main effect. Tillage was the sub-plot, and winter canola/wheat served as the sub-sub-plot. Two varieties each of canola and wheat were tested as sub-sub-sub plot. Fall stand, seed yield, and double crop soybean yield were measured for all plots. Interactions between either pair of canola or wheat varieties with previous crop or tillage system were not detected either season. Canola produced a higher yield after a previous crop of corn than after a previous crop of soybean in 2005-2006. In 2007-2008, the yield of canola after soybean was higher however this difference was not significant. No influence of previous crop on wheat yield was detected either season. The influence of tillage on canola and wheat yield was inconsistent across seasons. Canola produced a higher yield under reduced till in 2007-2008, but not in 2005-2006. In 2005-2006, wheat produced a higher yield under no-till and a higher yield under reduced till in 2007-2008. In 2007-2008, a significant interaction between previous crop and tillage system was detected for both canola and wheat. Canola yield was significantly reduced by no-till after corn but not so by no-till after soybean. Wheat yield was significantly lower following corn no-till than following soybean no-till, however, there was no difference in wheat yield following corn or soybean under reduced till. The yield of double crop soybean did not differ following winter canola or winter wheat either season, however in 2005-2006, yield was higher following corn after either canola or wheat. The double crop soybean yield was 1,421 hg/ha in 2005-2006 and was 3,161 kg/ha in 2007-2008. The results herein indicate that canola and wheat can be profitably grown behind either corn or soybean and under either a reduced till or a no-till system. However, these results are inconclusive as to which combination of previous crop or tillage system should be recommended for either winter crop. It does appear that there is a greater concern establishing a canola stand under a no-till system. Canola provided greater gross revenue over that of wheat both seasons, even after considering the additional canola seed and nitrogen costs. When combined across seasons, canola had a mean yield of 3,838 kg/ha and a mean revenue of $1,236/ha. Wheat had a mean yield of 5,511kg/ha and a mean revenue of $939/ha. The seed and nitrogen cost differential was computed at $70. Thus, the canola crop provided revenue that was 25% higher per hectare than the wheat crop.

In high jumping, the Fosbury Flop technique is currently used by all elite high jumpers throughout the world. The technique involves an acrobatic bar clearance at the end of a curved approach run. Initially the curved approach was considered to be no more than an idiosyncrasy of Dick Fosbury. However, the curved approach remains the preferred approach among elite jumpers, and therefore can be expected to be advantageous in high jumping. Speculations on the possible advantages of the curved approach have been made, but most are not based on experimental data and all lack convincing mechanical explanations. In order to understand the contribution of the curved approach to high jumping technique, the characteristics of the approach needed to be examined. Analysis of the 15 m approach phase of the high jump posed a. challenge in terms of obtaining the appropriate size of image and field of view. A number of image analysis systems were evaluated before one with the appropriate accuracy was selected. A total of 15 jumps performed by two elite high jumpers in two competitions were analysed. It was found that the curve through the foot placements tightened towards the end of the approach. Concurrently the inward body tilt towards the centre of the curve decreased resulting in an angular velocity about the frontal axis of the body. This suggested that the curved approach was used to provide the somersault rotation over the bar. In order to test this hypothesis a computer simulation model of the approach phase was developed and evaluated using the data from the image analyses. The model was used to explain the mechanics underlying the curved approach in the Fosbury Flop. It was found that tightening of the foot placement curve towards the end of the approach generated somersault rotation and also contributed to twist rotation at takeoff.

In the past two decades, a number of artificial molecular motors have been constructed using organic molecules as components which can perform unidirectional motion. Among the best-known examples are the light-activated molecular rotary motors synthesized and analyzed in B. L. Feringa's lab. Yet there is limited understanding of the photoisomerization and thermal isomerization processes that control the speed and energy conversion efficiency of these molecular devices. The present thesis work aims at: 1) developing a computational methodology to provide the atomic and electronic details that allow for quantitative descriptions of light-activated molecular motion, 2) improving the understanding of the physical principles governing photo- and thermal-isomerization processes in specific molecular systems, and 3) proposing a new strategy of molecule design to assist experimental investigations. A key component in our methodology is the calculation of the potential energy surface (PES) spanned by collective atomic coordinates using ab initio quantum mechanical methods. This is done both for the electronic ground state, which is relatively straightforward, and for the photo-excited state, which is more involved. Once the PES is known, classical statistical mechanical methods can be used to analyze the dynamics of the slow variables from which information about the rotational motion can be extracted. Calculation of the PES is computationally expensive if one were to sample the very high dimensional space of the atomic coordinates. A new method, based on the torque experienced by individual atoms, is developed to capture key aspects of the intramolecular relaxation in terms of angular variables associated with the rotational degrees of freedom. The effectiveness of the approach is tested on specific light-driven molecular rotary motors that were successfully synthesized and analyzed in previous experiments. Finally, based on the experience accumulated in this study, a new molecular rotary motor driven by visible light is proposed to reach MHz rotational frequency.

Infrared absorption spectra of HC1 and HBr, suspended in solid argon, krypton and nitrogen, were recorded in order to obtain information on intermolecular forces. SO₂ in argon and nitrogen, and CO in argon were also studied. The spectra were observed in the temperature range from liquid helium temperatures up to the melting point of the matrix. The halogen acids gave more complicated spectra in the noble gas matrices than in nitrogen. This has been correlated with the different thermal properties of the matrix materials. Matrix to solute ratios from 100 to 800 to 1 were used and evidence was found for solute-solute interactions, arising from incomplete isolation of solute molecules at the lower ratios. During the warm-up period at the end of an experiment, additional peaks appeared in the spectra. It is suggested that these new peaks were due to clusters of solute molecules produced by diffusion of the solute through the lattice. Semi-empirical calculations were carried out to estimate shifts of vibrational frequencies of the trapped molecules. From these calculations it was concluded that repulsive intermolecular forces play an important part in determining the magnitude, and direction of the shifts. A first order perturbation calculation was made, using a Lennard-Jones' potential, to determine the effect of the matrix on the rotational energy levels of a trapped molecule. Spectra of the clathrate-hydrates of SO₂, H₂S and krypton were recorded at liquid nitrogen temperatures, and the SO₂ hydrate was studied in the temperature range from 4° to 120° K. The spectrum of the water skeletal vibrations exhibited several interesting features. The assignment of the 1600 cmˉ¹ and 2200 cmˉ¹ peaks to v₂ and v₂ + vR was confirmed and a new peak at 2410 cmˉ¹ was observed. A lattice mode in the spectrum of the S0₂ hydrate was observed in combination with V₃ of SO₂. / Science, Faculty of / Chemistry, Department of / Graduate

A series of Cu(II)-63 dithiocarbamates with alkyl and cycloalkyl substituents of various shape, size and rigidity has been prepared. Their rotational correlation times (Ƭ₂) were measured (in the fast motional regime) in toluene using the line-widths of their ESR spectra. The ESR spectra were recorded on paper tape with a digital acquisition system and analysed on an Amdahl 470 computer utilising specially written programs. This procedure results in a substantial improvement in precision over earlier manual methods. The observed correlation times were compared with those calculated by the QLRF model, the conditional free rotation model, the Stokes-Einstein and Perrin 'stick' hydrodynamic models and the 'slip' hydro- -dynamic model. The results in relation to Pecora's extension of the hydrodynamic model are also discussed. The statistical mechanical and 'stick' hydrodynamic models proved unsatisfactory. The results are adequately described by the 'slip' hydrodynamic model with an additional term ascribable to a free-rotation correlation time (Ƭ₀); i.e. Ƭ₂ = Cn + Ƭ₀ ¯¯¯ Ƭ where n is the viscosity of the solvent and C is a function of the size and shape of the molecule calculated from the ' slip ' theory. / Science, Faculty of / Chemistry, Department of / Graduate