Current Virginia soft red winter wheat (Triticum aestivum L.) management strategies have been in place for over 20 years. A new advanced intensive management (AIM) system has been evaluated in order to improve Virginia wheat yields and attempt to bring state average wheat yields of 4288 kg ha⁻¹ more closely in-line with the maximum yield achieved in the Virginia Tech Official Soft Red Winter Wheat Trials of 7400 kg ha⁻¹. Increases in nitrogen (N) fertilizer application rates and splits, a chelated micronutrient blend, increased seeding rates, and a "no tolerance" pest control methodology were compared to current intensive management practices in this study. Additional fall N application and an increased seeding rate resulted in an increased number of tillers m-2 at growth stage (GS) 25 and biomass at GS 30. This increased number of tillers may lead to a greater amount of viable grain head production and increased wheat yields. Higher seeding and N application rate resulted in dramatically increased lodging in 2009 with resultant yield loss. Grain yield was significantly affected by management type in three of six instances. The number of heads m-2 was the yield component factor most influenced by factors tested in these studies. / Master of Science

Corn silage is one of the major components in dairy cattle rations in the United States. Many factors affect the nutritional composition of corn for silage, such as cropping system, including cover crops, and the composition of the corn plant cell wall. The objectives of the first study were to determine the nutritional quality of different winter crops for silage and to determine the impact of the various winter crops on the succeeding productivity of corn and sorghum. Experimental plots were planted with 15 different winter crop treatments: 5 winter annual grasses in monoculture or with one of two winter annual legumes (crimson clover [CC] and hairy vetch [HV]). After harvesting the winter crops, each plot was planted with either corn or forage sorghum. Crimson clover increased DM yield compared to monocultures but HV did not. Adding legumes increased the crude protein concentration, but reduced the fiber and sugar concentrations of the forages. Even though in vitro neutral detergent fiber digestibility was reduced with the addition of legumes, the concentration of highly digestible non-fibrous components is greater in the mixtures than the monocultures, increasing the nutritive value of the silage. The objective of the second study was to determine the cell wall (CW) composition along the corn stalk. Three phytomers of corn plants were examined: center (C) of ear insertion, upper (U) and lower (L) phytomers. Each phytomer was cut into 4 sections: top (T), middle (M), bottom (B), and node (N). The CW, uronic acid (UA), glucose (GLU), and lignin concentrations did not change among phytomers. The concentrations of arabinose (ARA) and xylose (XYL) were greater in the U than in the L phytomers. Concentrations of CW, ARA, and XYL increased from B to T within the phytomer, but UA and GLU concentrations decreased from B to T. Lignin did not change within the phytomer. In mature corn for silage, changes within the corn internode may be more useful in determining how the environment changes the CW. / Ph. D. / Corn silage is one of the major components in dairy cattle rations in the United States. Many factors can affect the nutritional composition and digestibility of corn for silage, including the crops planted before the corn and the maturity of the corn. I first explored the nutritional quality and potential of different winter crops for use as silage and how these various winter crops impacted the succeeding productivity of corn and sorghum. We used 15 different winter crop treatments: 5 winter annual grasses in monoculture or mixed with one of two winter annual legumes (crimson clover and hairy vetch). After harvesting the winter crops, corn and forage sorghum were planted. The addition of legumes increased winter crop yield compared to monocultures. Adding legumes increased the protein concentration, but reduced the reduced the fiber and sugar concentrations of the winter crops. Fiber digestibility was reduced with the addition of legumes. The type of grass and legume did not change the nutrient composition of the corn and sorghum. I then explored how the cell wall (CW) composition changes along the corn stalk. Corn plants are split up into phytomers. Each phytomer contains a leaf, a section of the stalk called an internode, and a node (connects internodes). Phytomers at the top of the corn plant are less mature than ones at the bottom, and maturity increases from bottom to top within a corn internode. Three phytomers of individual corn plants were each cut into 4 sections: top, middle, bottom, and node. In plants, the primary cell wall is deposited first. The primary cell wall contains cellulose, hemicellulose, and pectin. The secondary cell wall is deposited after growth. The secondary cell wall is composed of cellulose, hemicellulose, and lignin. Corn that is harvested for cows to eat is usually at a late stage of maturity. Therefore, in our study we saw very few differences among phytomers as cellulose, hemicellulose, pectin, and lignin had most likely been fully deposited. However, within the corn internode, we did see variability in the corn plant cell wall. The cell wall concentration overall increased with maturity within the corn internode. Further, arabinose and xylose concentrations (sugars from hemicellulose) also incased with maturity. Hemicellulose is important in connecting the rest of the cell wall to lignin later in maturity. The concentration of uronic acids from pectin and glucose from cellulose decreased with maturity because these are typically deposited first within the plat cells and then level off once lignin is deposited. In mature corn for silage, changes within the corn internode may be more useful in determining how the environment changes the CW.

This thesis is concerned with architecture and its changes through four seasons. It is about drawing new images of a building in different seasons. Like trees change their leaves in seasons and like people change their clothes in seasons, this project is about architecture changing its architectural elements in four seasons. It all began with an imagination of how a building would respond differently in each of the four seasons. The project, located at the waterfront of Old Town, Alexandria, Virginia, is an Aquatic Center with swimming pools, changing areas, saunas, fitness area, and massage areas. The Aquatic Center creates different images to its visitors through surrounding natures and their changes, architectural elements and their movements, visitors and their activities. The goal was to provide people unique and different experiences every time they visit. / Master of Architecture

Doctor of Philosophy / Department of Agronomy / Phillip W. Stahlman / Saflufenacil is an experimental herbicide for control of broadleaf weeds in various crops including several herbicide resistant weed biotypes. Wheat is highly tolerant to preplant and preemergence applications of saflufenacil, but winter wheat growers prefer to apply herbicides postemergence (POST) in early spring. Objectives of this research were to (1) evaluate winter wheat and four common broadleaf weed species response to POST treatments of saflufenacil applied alone and in combination with bentazon or auxin herbicides at various rates both with and without adjuvants, and to (2) determine the possible mechanism(s) responsible for crop safening observed when saflufenacil is applied with 2,4-D amine or bentazon in winter wheat. Growth chamber, greenhouse, and field studies showed saflufenacil at a minimum rate of 25 g/ha controlled blue mustard and flixweed >85% when saflufenacil was applied alone or mixed with dicamba, 2,4-D amine, 2,4-D ester, or MCPA ester. Also, mixtures of bentazon with 13 g/ha of saflufenacil resulted in death of kochia, but increasingly higher rates of 2,4-D amine were needed to achieve 90% growth reduction when saflufenacil rates were decreased from 50 to 25 to 13 g/ha. In general, most of the saflufenacil combinations tested controlled henbit <85%. Leaf necrosis and stunting of winter wheat were reduced by tank mixing saflufenacil with dicamba, 2,4-D amine, or bentazon, but not with MCPA ester or 2,4-D ester. Including nonionic surfactant (NIS) in mixtures of saflufenacil plus 2,4-D amine resulted in significant wheat injury similar or greater than injury caused by saflufenacil plus NIS. Finally, 2,4-D amine enhanced saflufenacil absorption into winter wheat plants, whereas bentazon reduced absorption of saflufenacil. No more than 11% of applied saflufenacil translocated out of treated leaves to other plant parts when applied alone or when saflufenacil was mixed with 2,4-D amine or bentazon. Metabolism of saflufenacil by wheat plants was not affected by tank mixing with bentazon, but saflufenacil metabolism was slowed by mixing with 2,4-D amine. Overall, these studies indicate saflufenacil can potentially be used POST in wheat at an optimum rate of 25 g/ha plus 2,4-D amine or dicamba to effectively control blue mustard and flixweed.

Several past studies have attempted to quantify the impact of winter weather conditions on highway mobility in terms of traffic volume, speed, and capacity. While consistent in their general findings, these studies have shown considerably different results in terms of effect size and contributing factors. More importantly, most of these studies have not attempted to model the effects of winter maintenance operations on mobility or isolate these effects from those due to snowstorm characteristics, rendering their results and the proposed methods of limited use for estimating the benefits of maintenance activities. This research attempts to address this gap through a statistical analysis of a data set that is unique in terms of spatial and temporal coverage and data completeness. The data set includes both event based and hourly observations of road weather and surface conditions, maintenance operations, traffic volume and speed, as well as several other measures, from 21 highway sections across the province of Ontario. Event based information is available for six winter seasons (2000 to 2006) at 19 of the sites. For this event based data a matched pair technique was employed to determine the changes in traffic volumes and speeds under matched conditions with and without snow events. A regression analysis was subsequently performed to relate the changes in traffic volume and speed over an event to changes in various contributing factors such as highway type, snow event characteristics and road surface conditions. A case study was conducted to illustrate the application of the developed models for quantifying the mobility impact of road surface condition and the mobility benefit of winter maintenance operations. Complete hourly records were available for all 21 sites for three winter seasons. This was used to perform the evaluation on an hourly basis. A matching technique is employed to assign hour-by-hour median speeds observed under typical weather and road surface conditions to each hour of a snowstorm event. A regression analysis is subsequently performed to relate changes from average hourly speed to various contributing factors such as highway type, weather conditions and maintenance operations. Effects of maintenance operations are represented by an intermediate variable called road surface condition index (RSI). A case study is conducted to illustrate the application of the developed models for quantifying the mobility impact of winter snowstorms and the mobility benefit of maintenance operations. The models developed in these analyses confirmed the relationships between weather variables and traffic volume and speed described in the literature. In addition a strong association between road surface condition and traffic volumes and speed was identified.

Thesis (M.Sc. )--Memorial University of Newfoundland, 1997. / Bibliography: leaves 137-145.

The stratospheric and mesospheric wind field in winter is dominated by the stratospheric polar vortex, which reaches out up into the mesopause region and leads to strong westerlies there in winter. On the other hand, the tropospheric mean winter wind field is also connected with the polar vortex which thus can be considered as being extended from the surface up to the lower thermosphere. lt is found that the winter mesopause region zonal winds, as measured at the Collm Observatory of the University of Leipzig, are closely connected with the North Atlantic Oscillation (NAO) being an integrated measure for the northem hemispheric mean circulation. The NAO itself is found to be a measure for Central Europe winter temperatures. Thus also the mesopause region winds are closely correlated to the Central European winter surface temperatures. / Das stratosphärische und mesosphärische Windfeld wird im Winter wesentlich vom stratosphärischen Polarwirbel bestimmt, der von der Stratosphäre bis in die Mesopausenregion reicht und dort zu starken Westwinden führt. Auf der anderen Seite ist die mittlere troposphärische Zirkulation ebenfalls mit dem stratosphärischen Wirbel korreliert, so daß letzterer als von der Erdoberfläche bis in die untere Thermosphäre reichend betrachtet werden kann. Aus diesem Grund sind die mittleren Zonalwinde, gemessen am Observatorium Collm der Universität Leipzig, mit der Nordatlantikoszillation (NAO) korreliert. Andererseits hat die NAO einen starken Einfluß auf mitteleuropäische Wintertemperaturen, und damit ist der Wind im Mesopausenbereich ebenfalls mit den Wintertemperaturen korreliert.

Doctor of Philosophy / Department of Agronomy / Kraig L. Roozeboom / Previous research has revealed that winter wheat (Triticum aestivum L.) yields are often reduced following grain sorghum [Sorghum bicolor (L.) Moench] compared to wheat after other summer crops. The objectives of the study were to: (a) evaluate grain sorghum residue management strategies to improve the performance of a following winter wheat crop in no-till systems; (b) determine grain sorghum hybrid characteristics that facilitate planting wheat following grain sorghum, and identify winter wheat cultivars that are suitable for planting after grain sorghum; (c) evaluate effect of environment, sampling time, and grain sorghum hybrid plant pigmentation on phenolic acid concentration in sorghum residues. Experiments were conducted in environments suitable for planting winter wheat following a summer crop. Treatments for objective one were: glyphosate (pre-harvest application, post-harvest, none), residue (removed, chopped, left standing), and nitrogen (34 kg ha⁻¹ applied to residue, none). Treatments for objective two and three were grain sorghum hybrids representing three maturities (early, medium, medium-late) and two plant pigmentations (red, tan), wheat cultivars occupying significant planted acreage and having favorable performance within the region. Wheat yields increased in two environments by 217 and 630 kg ha⁻¹ when glyphosate was applied to the sorghum pre-harvest. Residue chopping or removal either had no effect or a negative effect on wheat yields compared to residue left standing. Nitrogen applied to the sorghum residue increased wheat yields in only one environment. Grain sorghum hybrid characteristics did not influence winter wheat yields in any environment, but winter wheat cultivar did influence grain yields of the winter wheat in three of the four environments. Breakdown of phenolic acids depended on environment. Results for these studies indicate that wheat yield after a grain sorghum crop can be maximized by planting a red-pigmented sorghum hybrid of an early or medium maturity, desiccating the sorghum crop with pre-harvest glyphosate if it can be applied to the sorghum roughly 45 to 50 days before a frost, and with a wheat cultivar that is well suited to no-till planting.

Call number: LD2668 .T4 1979 F85 / Master of Science

Résumé : L’Arctique est particulièrement sensible aux changements climatiques et a récemment subi des modifications majeures incluant une diminution dramatique de l’extension de la glace de mer. Notre capacité́ à modéliser et à potentiellement réduire les changements climatiques est limitée, en partie, par les incertitudes associées au forçage radiatif induit par les effets directs et indirects des aérosols, qui dépendent de notre compréhension des processus impliquant les nuages et les aérosols. La charge des aérosols est caractérisée par l’épaisseur optique des aérosols (AOD) qui est le paramètre radiatif extensif le plus important et l’indicateur régional du comportement des aérosols sans doute le plus décisif. Une de nos lacunes majeures dans la compréhension des aérosols arctiques est leur comportement durant l’hiver polaire. Cela est principalement dû au manque de mesures nocturnes d’AOD. Dans ce travail, on utilise des instruments (lidar et photomètre stellaire) installés en Arctique pour mesurer, respectivement, les profils verticaux des aérosols et une valeur intégrée dans la colonne (AOD) de ces profils. En outre, les données d’un lidar spatial (CALIOP) sont utilisées pour fournir un contexte pan-arctique et des statistiques saisonnières pour supporter les mesures au sol. Ces dernières ont été obtenues aux stations arctiques d’Eureka (80◦ N, 86◦ W) et de Ny Ålesund (79◦ N, 12◦ E) durant les hivers polaires de 2010-2011 et 2011-2012. L’importance physique des pe- tites variations d’amplitude de l’AOD est typique de l’hiver polaire en Arctique, mais suppose une vérification pour s’assurer que des artefacts ne contribuent pas à ces variations (par exemple un masque de nuage insuffisant). Une analyse des processus basée sur des événements (avec une résolution temporelle ≈ une minute) est essentielle pour s’assurer que les paramètres optiques et microphysiques extensifs (grossiers) et intensifs (par particules) sont cohérents et physiquement conformes. La synergie photomètre stellaire-lidar nous permet de caractériser plusieurs événements distincts au cours des périodes de mesures, en particulier : des aérosols, des cristaux de glace, des nuages fins et des nuages polaires stratosphériques (PSC). Dans l’ensemble, les modes fin (<1μm) et grossier (>1μm) de l’AOD obtenus par photométrie stellaire (τ[indice inférieur f] et τ[indice inférieur c]) sont cohérents avec leurs analogues produits à partir des profils intégrés du lidar. Cependant certaines inconsistances causées par des facteurs instrumentaux et environnementaux ont aussi été trouvées. La division de l’AOD du photomètre stellaire τ[indice inférieur f] et τ[indice inférieur c] a été davantage exploitée afin d’éliminer les épaisseurs optiques du mode grossier (le filtrage spectral de nuages) et, par la suite, de comparer τ[indice inférieur]f avec les AODs obtenues par le filtrage de nuages traditionnel (temporel). Alors que les filtrages temporel et spectral des nuages des cas étudiés au niveau des processus ont conduit à des résultats bons à modérés en termes de cohérence entre les données filtrées spectralement et temporellement (les épaisseurs optiques des photomètres stellaires et lidars étant toutes deux filtrées temporellement), les résultats saisonniers semblent être encore contaminés par les nuages. En imposant un accord en utilisant un second filtre, plus restrictif, avec un critère de ciel clair ("enveloppe minimale du nuage"), les valeurs saisonnières moyennes obtenues étaient de 0.08 à Eureka et 0.04 à Ny Ålesund durant l’hiver 2010-2011. En 2011-2012, ces valeurs étaient, respectivement, de 0.12 et 0.09. En revanche les valeurs d’épaisseur optique de CALIOP (estimées entre 0 et 8 km) ont légèrement diminué de 2010-2011 à 2011-2012 (0.04 vs. 0.03). // Abstract : The Arctic region is particularly sensitive to climate change and has recently undergone major alterations including a dramatic decrease of sea-ice extent. Our ability to model and potentially mitigate climate change is limited, in part, by the uncertainties associated with radiative forcing due to direct and indirect aerosol effects which in turn are dependent on our understanding of aerosol and cloud processes. Aerosol loading can be characterized by aerosol optical depth (AOD) which is the most important (extensive or bulk) aerosol radiative parameter and arguably the most important regional indicator of aerosol behavior. One of the most important shortcomings in our understanding of Arctic aerosols is their behavior during the Polar winter. A major reason for this is the lack of night-time AOD measurements. In this work we use lidar and starphotometry instruments in the Arctic to obtain vertically resolved aerosol profiles and column integrated representations of those profiles (AODs) respectively. In addition, data from a space-borne lidar (CALIOP) is used to provide a pan-Arctic context and seasonal statistics in support of ground based measurements. The latter were obtained at the Eureka (80 ◦ N, 86 ◦ W) and Ny Ålesund (79 ◦ N, 12 ◦ E) high Arctic stations during the Polar Winters of 2010-11 and 2011-12. The physical significance of the variation of the small-amplitude AODs that are typical of the Arctic Polar Winter, requires verification to ensure that artifactual contributions (such as incomplete cloud screening) do not contribute to these variations. A process-level event-based analysis (with a time resolution of ≈ minutes), is essential to ensure that extracted extensive (bulk) and intensive (per particle) optical and microphysical indicators are coherent and physically consistent. Using the starphotometry-lidar synergy we characterized several distinct events throughout the measurement period: these included aerosol, ice crystal, thin cloud and polar stratospheric cloud (PSC) events. In general fine (<1 μm ) and coarse (>1 μm )modeAODs from starphotometry ( τ[subscript f] and τ [subscript c] ) were coherent with their lidar analogues produced from integrated profiles : however several inconsistencies related to instrumental and environmental factors were also found. The division of starphotometer AODs into τ[subscript ]f and τ [subscript c] components was further exploited to eliminate coarse mode cloud optical depths (spectral cloud screening) and subsequently compare τ [subscript f] with cloud-screened AODs using a traditional (temporal based) approach. While temporal and spectral cloud screening case studies at process level resolutions yielded good to moderate results in terms of the coherence between spectrally and temporally cloud screened data (both temporally screened starphotometer and lidar optical depths), seasonal results apparently still contained cloud contaminated data. Forcing an agreement using a more restrictive, second-pass, clear sky criterion ("minimal cloud envelope") produced mean 2010-11 AOD seasonal values of 0.08 and 0.04 for Eureka and Ny Ålesund respectively. In 2011-12 these values were 0.12 and 0.09. Conversely, CALIOP AODs (0 to 8 km) for the high Arctic showed a slight decrease from 2010-2011 to 2011-2012 (0.04 vs 0.03).