Spelling suggestions: "subject:"field.""
31 |
Quantificando o potencial de expansão sustentável da produção de amendoim no Estado de São Paulo / Assessing the potential for sustainable intensification of peanut production in the State of Sao Paulo - BrazilAlves, Bruno Araújo 14 March 2018 (has links)
O amendoim (Arachis hypogaea L.) é originário da América do Sul e foi amplamente disseminado pelo mundo, provavelmente por causa do seu sabor agradável e valor nutritivo. A cultura do amendoim é uma alternativa em sistema de rotação de culturas em áreas de cana-de-açúcar no momento da reforma dos canaviais, sendo esta a razão pela qual o Estado de São Paulo, principal produtor de cana, seja também o principal produtor brasileiro de amendoim. A aplicação do conceito da eficiência de produção agrícola para avaliação da cultura do amendoim pode fundamentar análises estratégicas para o setor. Uma das ferramentas usadas para este tipo de aplicação são os modelos baseados em processos. Dentre os modelos de crescimento para a cultura do amendoim já existente, destaca-se o incluído no sistema computacional DSSAT, denominado CROPGRO, que tem sido bastante aplicado em todo o mundo por pesquisadores da área. O desenvolvimento de modelos próprios por pesquisadores intensifica o processo de aprendizado e auxilia na redução de incertezas. O objetivo deste trabalho foi gerar conhecimento sobre a cultura do amendoim quanto a necessidade hídrica, conciliado ao desenvolvimento e calibração de modelos de simulação para quantificação da eficiência de produção agrícola nas principais regiões produtoras do Estado de São Paulo. A calibração do modelo CROPGRO-Peanut foi eficiente em simular a fenologia, para as variáveis vegetativas o índice d de Wilmott foi satisfatório para IAF (0,88 a 0,90), N° de folhas (0,58 a 0,85), AF específica (0,82 a 0,98), massa vegetativa (0,94 a 0,98) conforme a reposição hídrica aplicada, com valores de r2 acima de 0,65. Quanto as variáveis produtivas, embora os índices d e r2 foram satisfatórios, a EF foi baixa para ambos os tratamentos. Já o Simulador agronômico simplificado para Arachis hypogaea (SASAH), modelo inicialmente proposto neste trabalho pode ser considerando ainda em fase de construção e necessita de ajustes adicionais em seus algoritmos, não sendo utilizado na tese para simulação da produção potencial e atingível do amendoim. A eficiência média da produção no estado de São Paulo é de 52%, variando entre 33% em Ribeirão Preto até 72% em Marília. / Peanut (Arachis hypogaea L.) originates from South America and was widely disseminated throughout the world, probably because of its pleasant taste and nutritional value. The peanut crop is an alternative in a system of crop rotation in areas of sugarcane at the time of sugarcane reform, which is why the State of São Paulo, the main producer of sugarcane, is also the main producer Brazilian peanut. The application of the concept of agricultural production efficiency to evaluate the peanut crop can support strategic analysis for the sector. One of the tools used for this type of application is process-based models. Among the growth models for the existing peanut crop, the one included in the DSSAT computer system, called CROPGRO, has been widely applied by researchers in the area. The development of own models by researchers intensifies the learning process and helps reduce uncertainty. The goal of this work was to generate knowledge about the peanut crop as the water requirement, the development and calibration of simulation models to quantify the agricultural production efficiency in the main producing regions of the São Paulo State. The calibration of the CROPGRO-Peanut model was efficient in simulate the phenology, for the vegetative variables the Wilmott index was satisfactory for LAI (0.88 to 0.90), N° of leaves (0.58 to 0.85), Specific AF (0.82 to 0.98), vegetative mass (0.94 to 0.98) according to the applied water replacement, with r2 values above 0.65. Regarding the productive variables, although the indices d and r2 were satisfactory, the EF was low for both treatments. The simplified agronomic simulator for Arachis hypogaea (SASAH), a model initially proposed in this work, can be considered still in the construction phase and requires additional adjustments in its algorithms, and it is not used in the thesis to simulate the potential and attainable yield of peanuts. The average efficiency of production in the state of São Paulo is 52%, ranging from 33% in Ribeirão Preto to 72% in Marília.
|
32 |
A comparison of glacial and land-use controls on erosion in the northeastern United StatesAmes, Elisabeth M. January 2018 (has links)
Thesis advisor: Noah P. Snyder / Global studies assert that anthropogenic activity now leads to disproportionately higher rates of landscape change compared with background geomorphic processes. This study explores the relative influence of anthropogenic, glacial, and geologic processes on erosion rates (E) in the northeastern United States (NEUS) by analyzing published erosion and sedimentation data across multiple methods and timescales. I compile erosion rates and sediment yields from records of stream gauging, reservoir sedimentation, lake sedimentation, cosmogenic nuclides in stream sediment, and thermochronology. These data serve as a comparison point for quantified volumes of sediment deposited in valley bottoms as a result of European settlement in the NEUS, where glacial history may influence the availability of erodible sediment and, as a result, the relative magnitude of deposited sediment. I hypothesize that E in the formerly glaciated region will be lower than unglaciated E over last century (stream gauging and reservoir sedimentation) timescales due to the erosive power of continental glaciation and resultant thin upland soils, and that there will be an increase in E evident over the last century as a result of human influence. 499 sites with location data were compiled across the NEUS, converted to erosion rate (mm/yr) and sediment yield (Ys; t km-2 yr-1), and analyzed using statistical z-tests to determine whether the population means are significantly different. Mean E from all record types across both the glaciated and unglaciated NEUS exhibits a range smaller than one order of magnitude (0.012-0.055 mm/yr), much less variable than order-of-magnitude differences reported by other researchers comparing modern and geologic erosion, both regionally and globally. Last century timescales exhibit higher E in the unglaciated region than the glaciated region, but only reservoir sedimentation shows a significant difference in E between regions (0.012 vs. 0.055 mm/yr; glaciated and unglaciated, respectively); stream gauging E did not exhibit a significant regional difference, likely due to the large basin sizes, short measurement timescales, and disproportionate spatial distribution of the measurements. E does not increase from geologic to last century timescales: late Quaternary (lake sedimentation and cosmogenic nuclide) records consistently yield lowest E, with geologic (thermochronology) records showing the highest E in both regions, perhaps indicating the relative importance of E over timescales during which major orogenies were occurring in the NEUS. The similarities in mean E and large range of the distributions of all timescales, however, point to the relative stability of E over time in the NEUS. / Thesis (MS) — Boston College, 2018. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.
|
33 |
Early vigour : its role in enhancing the productivity of wheat grown in South Australia / David Sloane.Sloane, David January 1999 (has links)
Bibliography: leaves 196-220. / xvi, 229 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis investigates the role of crop agronomy and genotype in improving early vigour with a view to increasing grain yield. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy and Farming Systems, 1999
|
34 |
Effects of partial annealing on the tensile deformation behavior of heavily cold-rolled aluminumChen, Chun-hao 24 July 2007 (has links)
none
|
35 |
Innnovative wholesale carcass fabrication and retail cutting to optimize beef valuePfeiffer, Kyle David 12 April 2006 (has links)
This study evaluated innovations in beef wholesale carcass fabrication that may
have potential for improving subprimal yield and overall value of the beef carcass.
Thirty beef carcasses, equally representing USDA Choice and Select and USDA yield
grade 1 and 2, were selected from a commercial processing facility and transported to
Texas A&M University for subsequent fabrication. Beef sides were utilized in
comparing a conventional carcass fabrication style to a more innovative method.
Innovative forequarter subprimal yields were greater (P < 0.001) for the brisket, ribeye
roll, blade meat, and back ribs. The innovative method resulted in greater subprimal
yield and less lean trim (P < 0.001) from the forequarter. Innovative hindquarter
subprimal yields were greater (P < 0.001) for the tenderloin, top sirloin cap, bottom
sirloin tri-tip, and round tip. Hindquarter subprimal yield and lean trim were not
affected (P > 0.05). Value was greater for the innovative forequarter (P < 0.001) and
hindquarter (P < 0.01); value was increased by more than seven dollars per beef side,
thus greater than fourteen dollars per beef carcass. Selected subprimals were evaluated
in a retail cutting test. Experienced retail professionals were utilized in fabricating the
retail cuts. In general, the innovative retail subprimals performed equally or better than
the conventional subprimals. The M. Serratus ventralis fabricated from the innovative
side, comprising over 4.5% of the innovative forequarter, generated greater than 57%
steak yield and 94% saleable yield. Innovative carcass fabrication techniques resulted in
greater subprimal yield and increased the value of the entire beef carcass. These results
were verified by retail cutting tests conducted on selected subprimals.
|
36 |
Effects of feeding level and forage/concentrate ratio on milk production and performance of crossbred lactating cows /Mai, Van Sanh. January 2001 (has links)
Thesis (Ph. D.)--Sverges lantbruksuniversitet, 2001. / Based on 4 previously prepared or published papers reprinted here. Includes bibliographical references.
|
37 |
Effects of level of concentrate supplementation on milk production and ruminal pH in lactating cows on pastureClevenger, Gatha R. January 1900 (has links)
Thesis (M.S.)--West Virginia University, 2010. / Title from document title page. Document formatted into pages; contains viii, 65 p. : col. ill. Includes abstract. Includes bibliographical references.
|
38 |
The effects of reducing dietary phosphorus and nitrogen by the addition of bluegrass straw to the rations of early to mid-lactation Holstein dairy cowsHuisman, Andrina Christine. January 2009 (has links) (PDF)
Thesis (M.S. in animal sciences)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 15, 2010). "Department of Animal Sciences." Includes bibliographical references (p. 67-77).
|
39 |
Planting Dates for Small Grains in ArizonaOttman, Michael J 05 1900 (has links)
Revised; Original Published: 2004 / 3 pp. / Planting at the optimum time is probably the most important cultural practice in producing high small grain yields. Wheat and barley crops that are planted too early or too late have lower yield potential no matter how they are grown after planting. However, small grains are sometimes planted later than optimum when grown in rotation with cotton or vegetables due to harvest timing in these crops. Therefore, the entire farm enterprise should be considered when deciding on a planting date for small grains.
|
40 |
An examination of endocrine and nutrient controls of milk protein production /Luimes, Paul Hendrik January 2002 (has links)
The control of milk protein production was investigated utilising two different approaches. The first model is one of intravenous infusion of atropine. Atropine, which decreases milk protein yield, has been theorised to act either by decreasing blood somatotropin (ST) concentration or by decreasing blood amino acid (AA) concentration. Thus, the first experiment was designed to test which mechanism, or both, is responsible for the effects on milk protein yield. Five lactating dairy cows were assigned to the following treatments which were administered intravenously: Saline (CONT), atropine (ATR), ATR + ST, ATR + AAs, and ATR + ST + AAs. Atropine treatment failed to decrease plasma ST concentration but did decrease plasma alpha-amino nitrogen concentration. Atropine treatment decreased milk protein yield but neither ST, AAs, nor ST + AAs were able to maintain milk protein yield at the CONT level when infused with ATR. It is clear that the treatments tested are not directly responsible for the decrease in milk protein yield due to ATR. Therefore, neither ST, AAs, nor ST + AAs appear to have direct control of milk protein production. Plasma insulin (INS) concentration was decreased and plasma IGF-I concentration was not decreased by ATR treatment. Insulin, therefore, presents itself as a candidate for direct control over milk protein synthesis. The second model is one of monitoring endocrine response to abomasal infusion of AAs mimicking the profile of milk protein with selective deletion of certain AAs. Six lactating dairy cows were subjected to the following treatments: Saline (negative control, NC), AAs (positive control, PC), PC minus methionine (PC-Met), PC minus lysine (PC-Lys), PC minus histidine (PC-His), and PC minus the branched-chain AAs (PC-BCAAs). All endocrine factors studied (ST, INS, glucagon & IGF-I) were affected by treatment. Plasma IGF-I concentration responded similarly, except for the PC-Met treatment, to milk protein yield (Weekes and Cant, 200
|
Page generated in 0.0251 seconds