Kochia and biennial wormwood are two weeds sometimes found growing in sunflower fields that may be difficult to control. Weed management in sunflowers is usually conducted using a combination of herbicides and mechanical weed control methods. Some farmers are growing sunflowers in reduced tillage systems, which may rely solely on herbicides to manage weeds; however, the spectrum of broadleaf weeds that can be controlled with herbicides is limited. Field experiments were conducted across southern Manitoba to determine the effect of kochia and biennial wormwood density and relative time of weed seedling recruitment on sunflower growth and development, yield and seed quality and to determine action thresholds for each weed. Early emerging kochia (plants that emerged at about the same time as the sunflowers) reduced sunflower yield by as much as 82%, which was greater than early emerging biennial wormwood plants, which reduced yield by as much as 27%. At low weed densities, each kochia plant reduced sunflower yield by 0.52% and each biennial wormwood plant reduced sunflower yield by 0.17%. As the density of early emerging kochia plants increased, sunflower height, stem diameter, leaf counts and head diameter were reduced in some of the experiments. Increasing densities of early emerging biennial wormwood plants had minimal effect on sunflower growth and development. Early emerging kochia and biennial wormwood plants both had the potential to reduce sunflower seed size and seed weight, while late emerging kochia and biennial wormwood (plants that emerged after the 4-leaf stage of the sunflowers) did not affect sunflower seed quality. The action threshold (5% sunflower yield loss) for early emerging kochia was 10 plants per metre square and the action threshold for early emerging biennial wormwood was 36 plants per square metre in the combined site-year analysis. Kochia or biennial wormwood plants that recruited after the 4-leaf stage of the sunflower crop did not affect sunflower yield, or seed quality.

Kochia and biennial wormwood are two weeds sometimes found growing in sunflower fields that may be difficult to control. Weed management in sunflowers is usually conducted using a combination of herbicides and mechanical weed control methods. Some farmers are growing sunflowers in reduced tillage systems, which may rely solely on herbicides to manage weeds; however, the spectrum of broadleaf weeds that can be controlled with herbicides is limited. Field experiments were conducted across southern Manitoba to determine the effect of kochia and biennial wormwood density and relative time of weed seedling recruitment on sunflower growth and development, yield and seed quality and to determine action thresholds for each weed. Early emerging kochia (plants that emerged at about the same time as the sunflowers) reduced sunflower yield by as much as 82%, which was greater than early emerging biennial wormwood plants, which reduced yield by as much as 27%. At low weed densities, each kochia plant reduced sunflower yield by 0.52% and each biennial wormwood plant reduced sunflower yield by 0.17%. As the density of early emerging kochia plants increased, sunflower height, stem diameter, leaf counts and head diameter were reduced in some of the experiments. Increasing densities of early emerging biennial wormwood plants had minimal effect on sunflower growth and development. Early emerging kochia and biennial wormwood plants both had the potential to reduce sunflower seed size and seed weight, while late emerging kochia and biennial wormwood (plants that emerged after the 4-leaf stage of the sunflowers) did not affect sunflower seed quality. The action threshold (5% sunflower yield loss) for early emerging kochia was 10 plants per metre square and the action threshold for early emerging biennial wormwood was 36 plants per square metre in the combined site-year analysis. Kochia or biennial wormwood plants that recruited after the 4-leaf stage of the sunflower crop did not affect sunflower yield, or seed quality.

No description available.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 444-462). Available also in a digital version from Dissertation Abstracts.

Sunflower is the most important oilseed crop in South Africa and accounts for approximately 60 % of all oilseeds produced locally. The primary by-products of the sunflower seed crushing industry provides high-value inputs towards the food and animal feed manufacturing sector in the form of edible oil and protein meal. Prior to 1996, the South African sunflower seed complex market was controlled by the Oilseed Board, which operated a single-channel pool scheme and regulated the marketing of oilseeds and oilseed products. Since the liberalisation of the South African agricultural sector, role-players have been fully exposed to the dynamics and risks of the international oilseed complex market. Over the years participants in the agricultural commodity markets have developed various instruments to assist them in their decision-making process – one of them being commodity modelling, which is described as a methodological technique that provides a powerful analytical tool for examining the complexities of commodity markets. In South Africa, many role-players in the various agricultural industries make use of a multi-sector commodity level partial equilibrium model better know as the BFAP sector model which is maintained by the Bureau for Food and Agricultural Policy (BFAP) at the University of Pretoria. The objective of this study was to expand the coverage of the existing BFAP sector model by developing a comprehensive system of equations for the total sunflower seed complex, which includes not only a partial equilibrium model for sunflower seed, but also sunflower oil and cake. In this study much emphasis was not only placed on the formation of prices of the various products, but also the application of the most suitable model structures in order to trace the behaviour of the various prices under real market conditions as accurately as possible. This study applied the methodology developed by the Food and Agricultural Policy Research Institute (FAPRI) and further adapted by the Bureau for Food and Agriculture Policy (BFAP) to develop the partial equilibrium model of the South African sunflower complex. The single equations were estimated by mainly using ordinary least squares (OLS), but in cases where the results of the OLS were contradictory to the theory or where insufficient data was available, calibration techniques were employed and the equations were synthetically constructed. The constructed model was applied to lay down a baseline projection for the total production and consumption blocks of sunflower seed, oil and oilcake. The baseline projections also formed part of the ex post validation of the model’s performance. Finally the consistency of the model was evaluated in the form of scenario analysis. Various real-world market- and policy-related shocks were imposed and the results were compared to the baseline projections. In general the model developed in this dissertation performed well and can be used to analyse the effects of economic, technological and policy changes on the South African sunflower seed complex. It also provides a sound structure for the development of a complete South African oilseed complex model that includes soybeans, canola, groundnuts, cotton and imported palm oil. Copyright / Dissertation (MScAgric)--University of Pretoria, 2010. / Agricultural Economics, Extension and Rural Development / unrestricted

When testing nine different sunflower cultivars in 32 South African environments (location x year), an Additive Main Effects and Multiplicative Interaction analysis (AMMI) identified sizeable genotype by environment (GxE) interaction. The first two Interaction Principal Components Axes (IPCA1 and IPCA2) were highly significant (p<0.001), but all the factors responsible for the GxE interaction could not be identified, as the causes of interaction seems to be of complex nature. IPCA1 captured 34% of the interaction SS with only 15.3% of the degrees of freedom, while IPCA2 captured 22.5% of the interaction SS with 14.5% of the degrees of freedom. This indicates that the AMMI2 model fits the data well and is parsimonious. Both cultivars and environments grouped together in quadrants according to their length of season when their respective IPCA1 and IPCA2 scores were plotted against each other. Environments from the warmer dry Western and Northern regions, including the Dry Highveld Grassland, Northern Arid and Central Bushveld, grouped in opposite quadrants, 1 and 3, while environments from the cooler moist Eastern regions, including the Moist Highveld Grassland grouped in opposite quadrants, 2 and 4. The factors responsible for the division between quadrants 1 and 3, as well as those responsible for the division between quadrants 2 and 4 could not be identified. The long-season cultivars were better adapted to the Northern and Western environments, while the medium-season cultivars were better adapted to the Eastern environments. Each quadrant was dominated by a different cultivar. Because the environments and cultivars could not be sufficiently described according to the factors responsible for the observed GxE interaction, cultivars can not be advised for specific environments. It is therefore presently recommended that cultivars which are more widely adapted to South African conditions, be selected. / Dissertation (MSc (Genetics))--University of Pretoria, 2004. / Genetics / unrestricted

Coronary stent placement is a routine treatment of coronary artery disease, the leading cause of death worldwide. Intravascular Optical Coherence Tomography (IVOCT) is a superior imaging assessment technique in coronary stenting. To characterize IVOCT artifacts, phantom blood vessels were constructed and metallic and bioabsorable coronary stents were deployed with and without phantom neointima. High resolution Micro-CT images of the stent strut were recorded as a gold standard and utilized to create a three-dimensional representation of a strut that was imported into computer optical simulations. Simulated IVOCT images were computed that include the IVOCT catheter, light reflection from stent struts with varying neointimal thickness and scattering in the vessel lumen. The simulation results along with IVOCT images of the phantom vessels were utilized to elucidate the mechanisms underlying the “sunflower effect”, bending of stent struts toward the imaging catheter and “merry-go-round” effect, variable apparent strut size of metallic stents. Atomic force microscopy was used to examine surface properties of metallic and bioabsorbale stents, revealing sources of the distinctive appearance of bioabsorable stents in IVOCT images. The model formed a basis to develop a correction algorithm to remove stent artifacts in clinical IVOCT images. / text

Made available in DSpace on 2014-06-11T19:22:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-12-08Bitstream added on 2014-06-13T19:07:32Z : No. of bitstreams: 1 lobo_tf_me_botfca.pdf: 211179 bytes, checksum: 0c0444539289f4a553456a621bf9f544 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O experimento foi conduzido na Fazenda São Manuel da Faculdade de Ciências Agronômicas da UNESP Campus de Botucatu, localizada no município de São Manuel. O objetivo foi avaliar a eficiência do lodo de esgoto como fonte de N à cultura do girassol. Adotou-se o delineamento experimental em blocos casualizado constituído por 6 tratamentos e 5 repetições. Os tratamentos foram: T0 - adubação mineral de acordo com o boletim 100, mas sem N; T1 - adubação química de acordo com o boletim técnico 100 do IAC; T2 - foi utilizado 50% do N proveniente do lodo de esgoto e o restante foi proveniente da adubação química; T3 - foi utilizado 100 % do N proveniente do lodo de esgoto; T4 - foi utilizado 150% do N proveniente do lodo de esgoto; T5 - foi utilizado 200% do N proveniente do lodo de esgoto. O cálculo do N proveniente do lodo de esgoto foi feito levado em consideração a sua taxa de mineralização do nitrogênio durante o ciclo da cultura. Utilizou-se o lodo de esgoto da Estação de Tratamento de Esgoto da cidade de Jundiaí/SP. A fonte de N químico adotado foi a uréia, a fonte de K foi cloreto de potássio, a fonte de P adotado foi o superfosfato simples, a fonte de B foi o ácido bórico. Cada parcela teve 100 m2 com um espaço de 3 m entre uma parcela e outra do mesmo bloco. O espaço entre blocos foi de 1,8 m. Foi utilizado o híbrido simples HELIO 251. Foi aplicado o lodo de esgoto nos tratamentos, 2 seguindo-se a incorporação com grade e posteriormente semeado o girassol. O girassol foi plantado em um espaçamento de 0,9 metros entre linha e 30 cm entre plantas, as adubações com P e K foram feitas no plantio de acordo com a análise de solo. O N foi feito logo após o plantio e no tratamento onde não foi efetuado a utilização do lodo de esgoto. Foi realizada uma cobertura nitrogenada... / The experiment was carried out at São Manuel Farm from Faculdade de Ciencias Agronomicas - UNESP, Botucatu, located in the city of São Manuel. The aim of the experiment was to evaluate the sewage sludge efficiency as a source of N for sunflower culture. An experimental outlining in radomized blocks was adopted, formed by 6 treatments and 5 repetitions. The treatments were as it follows: T0 - mineral fertilization according to bulletin 100 but without N; T1 - chemical fertilization according to IAC technical bulletin 100; T2 - 50% of Nitrogen from sewage sludge were used and the complementary part was obtained from chemical fertilization; T3 - 100% of Nitrogen from sewage sludge were used; 4 T4 - 150% of Nitrogen from sewage sludge were used; T5 - 200% of Nitrogen from sewage sludge were used. The calculation of nitrogen from sewage sludge was done considering its Nitrogen mineralization rate during the culture cycle. The sewage sludge was obtained from thre Sewage Treatment Station in the city of Jundiai - SP. The source of chemical N adopted was urea, the source of K was Potassium chloride, the source of P adopted was simple superphosphate, the source of B was Boric acid. Each part had 100 m2 with a space of 3 m between the parts in a same block. The space between blocks was 1,8 m. HELIO 251 simple hybrid was used. The sewage sludge was applied to the treatments, after that, an incorporation was made with a grid and the sunflower was sown. The sunflower was planted in a spacement of 0,9 meters betwen lines and 30 cm betwen plants, the fertilization with P and K was done at planting according to the soil analysis N was applied right after planting to the treatment where sewage sludge wasn t used. A nitrogenated coating was also done... (Complete abstract, click electronic access below)

By the year 2020, the nanotechnology market is expected to be three trillion dollars. With a quasi-exponential increase in consumer products, which contain nanomaterials, there is likely to be an equal increase in nanoparticles entering the environment. As a result, it is imperative to fully understand the relationship between nanomaterials and the food chain, including plants. In this study, the relationship between gold nanomaterials and the edible food crop, Helianthus annuus was investigated. First, an attempt to inhibit the uptake of nanoparticles into the roots of H. annuus was investigated by decreasing temperature. Second, the interactions between citrate-stabilized 20 nm diameter Au nanoparticles and sunflower seedlings were explored by exposing sunflower to a range of concentrations (3.0-40.0 mg/L). Nanoparticle sorption to roots was estimated using a linear isotherm with a distribution coefficient, Kd. Finally, sunflowers were exposed to 20 nm Au nanoparticles and 25x69 nm CTAB-stabilized Au nanorods. Results showed there was no change in biomass growth and transpiration between sunflowers that were exposed to nanoparticles and the unexposed controls. Thus Au gold nanoparticles (20 nm) were shown to have no phytostimulatory or phytotoxic effect on sunflower seedlings during eight to ten day exposure experiments. However, 25x69 nm gold nanorods were phytotoxic to sunflowers at 6.0 mg/L, indicating a potential charge or chemical effect of the surface coating of the nanorods compared to the spherical gold nanoparticles.

Crop lands around the world are becoming more salt-affected due to natural processes and agricultural practices. Due to this increase of salinization, acquisition of saline tolerant germplasm for breeding purposes is becoming a priority. Although cultivated sunflower is classified as a moderately salt tolerant crop, highly tolerant germplasm may be of value. The goal of this study was to screen Helianthus spp. in order to determine the salt tolerance of different genotypes. To accomplish this goal, a novel method of rapid screening was developed. Screening for tolerance at initial growth stages was accomplished by germinating seeds in varying concentrations of NaCl solution in petri dishes. Radicle lengths were measured as an indicator of tolerance. This method identified genotypes that are more tolerant than others during germination. Greenhouse trials were also conducted to ascertain morphological measurements during vegetative stages. Two field locations were chosen to screen germplasm for tolerance through physiological maturity; College Station, TX with low salt concentrations and Pecos, TX with high concentrations of salt in the soil and water. Vegetative growth measurements showed a significant genotype by environment interaction. Due to insect infestation in both locations, yields could not be accurately measured and thus compared between sites in 2010. Yields between locations in 2011 showed significant differences and identified germplasm more suited for cropping in salt affected soil. Seed oil content was determined with Fourier Transform Near-Infrared Spectroscopy. Seed oil content was not significantly different between locations, but was highly significant between genotypes. These screenings identified genotypes that are more salt tolerant than others.