Traditional vineyard floor management in humid regions consists of mown perennial grass or mown resident vegetation in aisles. Many vineyard sites in the eastern USA have climate and soil that support excessive vine vigor and rapid growth of aisle vegetation. Frequent mowing or unmanaged aisles are not a practical option. To explore vineyard floor management options for vine vigor and weed management while maintaining soil cover, vine balance, and fruit quality in the eastern USA, seven cover crop treatments: 1) grower control mown tall fescue (Festuca arundinacea L.), 2) chemically mown tall fescue (Festuca arundinacea), 3) little barley (Hordeum pusillum Nutt.), 4) downy brome (Bromus tectorum L.), 5) oilseed radish (Raphanus sativus L.), 6) spring oats (Avena sativa L.), 7) chemically mown sorghum-sudangrass (Sorghum bicolor L. Moench sp.) were established for the 2011 and 2012 growing seasons in a commercial Cabernet franc vineyard, planted in 2000, in southern Illinois, on an Menfro silt loam soil. In fall 2011, oilseed radish reduced the fresh weight of grapevine shoots removed with summer hedging 46% compared to the grower control. In 2012, spring oats increased the weight of grapevine shoots removed with summer hedging 160% compared to the grower control. In 2012, spring oats, and chemically mown sorghum-sudangrass produced 82% and 73%, respectively, greater pruning weights compared to grower control mown fescue, also, spring oats, downy brome, and chemically mown sorghum-sudangrass produced 54%, 48%, and 50%, respectively, greater yields compared to the grower control in 2012. Cover crop did not affect Ravaz index in 2011 or 2012. Chemically mown sorghum-sudangrass reduced total soluble solids in grape must 7% compared to the grower control in 2012. Downy brome produced the most ground cover and greatest weed control at bloom time in 2011 and 2012, and harvest time in 2011. In 2012, oilseed radish at veraison and harvest time produced 97% and 177%, respectively, more ground cover than grower control. The persistent mulch produced by little barley and downy brome followed by burndown herbicide, Rely ® (glufosinate 1 lb ai/gal) 76 fl oz/acre in August reduced their average weed cover by a range of 99% to 89% compared to all other treatments except grower control at harvest 2012. Downy brome established in vineyard aisles had the greatest potential for maintaining weed control at bloom and harvest time, while increasing yield without decreasing vine size. However, more research is needed to develop a residue management program which encourages self-reseeding of downy brome and little barley. In a season with above average rainfall, oilseed radish reduced excessively vigorous vine growth. While all treatments studied had the potential for vineyard use, downy brome and oilseed radish had the most potential to be readily incorporated into practical vineyard aisle management systems provided they are managed to produce moderate vine size, without adverse effects to yield or fruit quality, while still maintaining effective weed control.

<p>  </p> <p>Kentucky bluegrass is the most common cool-season turfgrass grown in the northern US. <br> The fact that Kentucky bluegrass requires s high quantity of fertilizers, pesticides, and irrigation to produce high quality turf has led to environmental concerns among policymakers, researchers, and consumers. To address this concern, turfgrass breeders have developed improved cultivars of low-input turfgrass species that aim to improve the sustainability of US lawns (Ghimire et al., 2019). For instance, tall fescue [(<em>Festuca arundinacea </em>Schreb.; syn. <em>Schedonorus arundinaceus</em> (Schreb.) Dumort., nom. cons.] and fine fescues (<em>Festuca </em>spp.) may represent viable options for residential and commercial buildings due to their outstanding performance under lower amounts of inputs such as irrigation, pesticides, and fertilizers (Watkins et al., 2011). Thus, adopting improved cultivars of low-input species may be a step towards reducing the use of inputs in landscapes (Simmons et al., 2011; Pooya et al., 2013). Yet, the production of low-input turfgrasses in the northern US is slow and limited, which leads to marketing and education obstacles that support their adoption. Thus, understanding factors that influence sod buyers to purchase low-input turfgrasses is imperative to increase the market share and the adoption of these turfgrasses. </p> <p>This study investigated the factors influencing sod buyers to purchase low-input turfgrass in the northern US, using tall fescue and fine fescue as low-input sod species. Using a logistic regression model, we assessed the determinants of low-input turfgrass purchase among sod buyers (i.e., athletic facilities, landscape contractors, garden centers, general contractors, lawn care, golf courses, and municipal parks). The logit model assumed the adoption decision to be driven by the buyers’ perception of the utility of buying low-input turfgrass species. Thus, the dependent binary variable Y equals 1 if the firm purchased tall or fine fescue in 2020, and 0 otherwise. The adoption is then expressed as a function of determinants, including the firm’s characteristics, supplier characteristics, sod attributes, and buyer’s perceptions. </p> <p>Data for this study came from a 2021 web-based survey of sod buyers located in 19 states of the Northern US. A total of 200 buyers completed the survey, including landscape contractors, golf courses, general contractors, lawn care services, and landscape maintenance firms who have purchased sod in 2020. The significant mean comparisons between adopters and non-adopters showed that adopters of low-input turfgrasses purchased most of their sod through contract agreements. The main suppliers of adopters were located at a closer distance to on-site delivery than the non-adopters. The logit regression results showed that low-input turfgrass adoption was positively influenced by the number of sod suppliers and managerial experience of the sod buyer. Landscapers were more likely to purchase tall fescue and fine fescue compared to golf courses and municipal parks. We found that distance from sod supplier to on-site delivery negatively impacted the purchase of low-input turfgrasses. Similarly, Kentucky bluegrass buyers were less likely to purchase low-input turfgrass species.</p>

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Submitted by PPG Engenharia El?trica (engenharia.pg.eletrica@pucrs.br) on 2018-10-31T13:57:50Z No. of bitstreams: 1 SILVIO CESAR ANTUNES DUTRA_DIS.pdf: 2550584 bytes, checksum: 3dae5cef4ef20b66d5c7a4db79ae5cad (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-11-01T11:50:43Z (GMT) No. of bitstreams: 1 SILVIO CESAR ANTUNES DUTRA_DIS.pdf: 2550584 bytes, checksum: 3dae5cef4ef20b66d5c7a4db79ae5cad (MD5) / Made available in DSpace on 2018-11-01T12:00:28Z (GMT). No. of bitstreams: 1 SILVIO CESAR ANTUNES DUTRA_DIS.pdf: 2550584 bytes, checksum: 3dae5cef4ef20b66d5c7a4db79ae5cad (MD5) Previous issue date: 2018-08-31 / Power converters are widely used in the context of power electronics. In the same way that transformers have a fundamental role in applications involving AC circuits, power converters modify voltage magnitudes in DC circuits. These devices can either present an output voltage higher than the input voltage, acting as a Boost converter, or lower, acting, in this case, as a Buck converter. The input and output signals can also present either a voltage source or a current source behavior, depending on the topology. This work presents a systematic study of the D converter operating in the continuous conduction mode, in permanent regime, including the qualitative and quantitative analyzes, resulting in a methodology of dimensioning of the converter, as well as its modeling in space of states, which makes feasible studies of control strategies for it. Although this is not a new topology, this converter has recently been reintroduced due to its ability to increase efficiency in the energy conversion process, especially in photovoltaic systems. However, this research is fully justified given the lack of similar work for the D converter topology. This study was validated from tests performed in the PSIM simulation software, in addition to MATLAB / SIMULINK. A laboratory prototype was specially constructed for validation purposes in a rapid prototyping platform, as well as the consequent implementation in a PCI, for use in future works. / Os conversores est?ticos s?o amplamente utilizados no contexto da eletr?nica de pot?ncia. Da mesma forma que os transformadores t?m papel fundamental nas aplica??es que envolvem circuitos alimentados em corrente alternada, os conversores est?ticos realizam a transforma??o de magnitudes de tens?o em circuitos de corrente cont?nua. Tais dispositivos podem tanto apresentar em sua sa?da um valor de tens?o superior em rela??o ao sinal de entrada, atuando como elevadores, quanto inferior, atuando, neste caso, como redutores. Estes tamb?m podem apresentar suas sa?das ou entradas com um comportamento de fonte de tens?o ou corrente, dependendo da topologia utilizada. Este trabalho apresenta um estudo sistematizado do conversor D operando no modo de condu??o cont?nua, em regime permanente, incluindo as an?lises qualitativa e quantitativa, resultando em uma metodologia de dimensionamento do conversor, bem como a sua modelagem em espa?o de estados, o que viabiliza estudos de estrat?gias de controle para o mesmo. Apesar de n?o se tratar de uma nova topologia, recentemente este conversor foi reintroduzido, devido a sua capacidade de aumentar a efici?ncia no processo de convers?o de energia, especialmente em sistemas fotovoltaicos. Esta pesquisa encontra justificativa dada a inexist?ncia de trabalhos semelhantes especificamente para a topologia do conversor D. Este estudo foi validado a partir de ensaios realizados no software de simula??o PSIM, al?m do MATLAB/SIMULINK. Um prot?tipo de laborat?rio foi especialmente constru?do para fins de valida??o em uma plataforma de prototipagem r?pida, bem como a consequente implementa??o do mesmo em uma PCI, para utiliza??o em trabalhos futuros.