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

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed April 26, 2007). PDF text: vii, 158 p. : ill. UMI publication number: AAT 3221294. Includes bibliographical references. Also available in microfilm and microfiche formats.

Made available in DSpace on 2014-06-11T19:29:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-01-25Bitstream added on 2014-06-13T18:39:33Z : No. of bitstreams: 1 nascimento_ms_me_ilha.pdf: 349212 bytes, checksum: de4a97b4521dc8d83da87f2f700a3e24 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O nitrogênio é o nutriente absorvido em maior quantidade pelo feijoeiro e o molibdênio, além da importância no processo de fixação de nitrogênio atmosférico, está associado ao metabolismo deste nutriente. Assim, o trabalho foi desenvolvido com o objetivo de avaliar, na cultura do feijão, em sistema de plantio direto, o efeito da aplicação de doses de nitrogênio em cobertura (0, 30, 60, 90 e 120 kg ha-1) bem como a aplicação foliar de molibdênio (0, 80 e 160 g ha-1), aplicado em duas fases de desenvolvimento das plantas (fase de desenvolvimento V3 e fase de desenvolvimento V4) utilizando sementes do cultivar Pérola. O delineamento experimental utilizado foi o de blocos casualizados com 30 tratamentos e 4 repetições. O estudo foi realizado em área experimental pertencente à Faculdade de Engenharia Campus de Ilha Solteira - UNESP, localizada no município de Selvíria-MS, em solo originalmente sob vegetação de cerrado e cultivado anteriormente com a cultura do milho. Foram realizadas as seguintes avaliações: população de plantas, matéria seca de plantas, nitrogênio nas folhas e grãos, molibdênio nas folhas e grãos, altura de inserção da primeira vagem, comprimento da primeira vagem, componentes de produção (número de vagens/planta, número de grão/planta, número de grão/vagem e massa de 100 grãos) e rendimento de grãos. A aplicação de Mo via foliar não 2 interfere na produtividade, e a aplicação de doses crescentes de nitrogênio em cobertura proporciona aumento crescente no teor de nitrogênio nas folhas e na produtividade de grãos. Termos para Indexação: Phaseolus vulgaris L., doses de N... / Nitrogen is the nutrient most uptaken by common bean plant, and molybdenum besides its importance to N fixation process, is associated to N metabolism. Thus, this micronutrient lack produces symptoms like those caused by N deficiency. This research had the objective of evaluating, on common bean crop, the effect of N levels application in side dressing (0, 30, 60, 90 and 120 kg ha-1) as well as the leaf application of Mo (0, 80 and 160 g ha-1) in development phases V3 and V4 under no tillage system. The experimental design was the randomized blocks with 30 treatments and 4 repetitions. The research was carried out in Selvíria-MS on soil previously cropped with corn. Stand, dry matter weight, N in leaves and seeds, Mo in leaves and seeds, 1st pod insertion height, 1st pod length, number of pod per plant, number of seed per plant, number of seed per pod, weight of 100 seeds and yield were evaluated. The application of Mo on leaf does not interfere on the productivity. The application of increasing levels of nitrogen in side dressing causes a crescent increase in nitrogen level on leaves and on grains productivity

No description available.

Sistemas com semeadura direta sobre palhada são cada vez mais utilizados na agricultura, e a ramulose do algodoeiro, causada pelo fungo Coletotrichum gossypii var. cephalosporioides Costa, é uma das doenças mais importantes na cultura. Foram realizados durante os anos de 2004/05, 2005/06 e 2006/07 na Escola Superior de Agricultura "Luiz de Queiroz", USP/ESALQ, em Piracicaba, SP, experimentos com a cultura do algodoeiro (Gossypium hirsutum L. var. latifolium Hutch), conduzidos sob preparo do solo convencional com semeadura convencional do algodoeiro, e ausência de preparo do solo com semeadura do algodoeiro sobre palhada de milheto, com o objetivo de avaliar se as modificações microclimáticas causadas pela utilização da palhada de milheto em relação às variáveis temperatura e duração de período de molhamento foliar (DPM) poderiam interferir no desenvolvimento e evolução da ramulose do algodoeiro. Foi utilizado também o Índice de Favorabilidade temperatura-molhamento para a ramulose do algodoeiro, que utiliza os parâmetros temperatura e DPM no seu cálculo para explicar o desenvolvimento da doença entre os dois sistemas de semeadura. Os dados microclimáticos foram medidos por uma plataforma de aquisição de dados na região central da área experimental. Em blocos alternados entre os dois sistemas de semeadura, o patógeno foi inoculado artificialmente nas subparcelas dos blocos, e a doença foi avaliada por escala de notas (1 a 5). As médias de notas de sintomas de ramulose foram submetidas à análise estatística, através de testes não paramétricos. A fim de avaliar se a ausência de preparo poderia interferir no desenvolvimento das plantas, este também foi avaliado. Os resultados permitiram concluir que sob semeadura convencional, houve nos dois primeiros anos maiores médias de massa seca, altura de plantas, IAF, e que no terceiro ano foram constatados maior número de raízes laterais e maior número de plantas com encurvamento da raiz pivotante sob semeadura direta. O aumento da severidade da ramulose foi decorrente de interações muito particulares para cada período, onde muitas variáveis estão envolvidas, ou seja, características intrínsecas ao patógeno, à fase de desenvolvimento da planta e às condições macro e microclimáticas; O IF-tm teve uma boa relação com o aumento da severidade e diferenças na severidade da ramulose entre os dois sistemas de semeadura; Pode ocorrer maior severidade da ramulose para sistemas de produção convencionais em maior proporção do que em sistemas com utilização de palhada em períodos onde os valores de IF-tm são altos, associados à ocorrência de chuvas; Com Índices de Favorabilidade temperatura-molhamento menores que 0,500 não se observau aumento efetivo da severidade da ramulose em quaisquer sistema de semeadura, mesmo havendo outras condições favoráveis; O sistema de semeadura utilizado não influenciou na produtividade da cultura. / Systems with direct seeding over mulching are more often used in agriculture, and the Ramulosis from the cotton plant caused by the fungus Coletotrichum gossypii var. cephalosporioides Costa, one of the most important diseases in cotton crop. During the years of 2004/05, 2005/06; and 2006/07at the University of Agriculture "Luiz De Quieroz", USP/ ESALQ, in Piracicaba, SP, experiments were made with the cotton crop (Gossypium hirsutum L. var latifolium Hutch), under the preparation of conventional tillage with conventional seeding of the cotton crop and the absence of the preparation of the tillage with the seeding of the cotton crop over the mulching of millet (Pennisetum glaucum L.) with the objective to evaluate if the modifications microclimates caused by the use of the mulching of millet in relation to the variables temperatures and the leaf wetness duration, (LWD) could interfere on the development of the ramulosis of the cotton crop. It was also used the Favorability Index for the ramulosis of the cotton crop which uses the temperature parameter and DPM in its calculation to explain the development of the disease between the two systems of seeding. The Weather variables data were measured by a platform of acquisition of data in the central zone of the experimental area. In alternated blocks between both systems of seeding, the pathogen was inoculated artificially and the disease was measured by scales from 1 to 5. The average of ramulosis was submitted to a statistic analysis through not parametric tests with the intent to find out if the absence of the preparation could interfere on the development of the plants, which was also evaluated. The results enable the conclusion that through conventional seeding, on the first two years there was an average of higher dry mass higher height of the plants, IAF, and in the third year it was found a higher number of lateral roots and a higher number of plants with bending on the primary roots over direct seeding. The increase of the severity of the ramulosis happened due to specific interactions for each period where many variables were involved, which means, intrinsic characteristic to the at the stage of the development of the plant and the conditions macro and microclimates. The Favorability Index had a good relation with the increase and the differences within the severity of the ramulosis between both systems of seeding. Higher severity of the ramulosis can occur for conventional systems of production in bigger proportions than in systems that uses the mulching in periods where the value of the IF-tm are high, associated to rain. With indications of Favorability Index lower than 0,500 there is no evidence of the effective increase of the severity of the ramulosis in any system of the seeding. The system of seeding used does not affect in the productivity of the cotton crop.

Orientador: Orivaldo Arf / Banca: Rita de Cássia Félix Alvarez / Banca: Salatiér Buzetti / Resumo: O nitrogênio é o nutriente absorvido em maior quantidade pelo feijoeiro e o molibdênio, além da importância no processo de fixação de nitrogênio atmosférico, está associado ao metabolismo deste nutriente. Assim, o trabalho foi desenvolvido com o objetivo de avaliar, na cultura do feijão, em sistema de plantio direto, o efeito da aplicação de doses de nitrogênio em cobertura (0, 30, 60, 90 e 120 kg ha-1) bem como a aplicação foliar de molibdênio (0, 80 e 160 g ha-1), aplicado em duas fases de desenvolvimento das plantas (fase de desenvolvimento V3 e fase de desenvolvimento V4) utilizando sementes do cultivar Pérola. O delineamento experimental utilizado foi o de blocos casualizados com 30 tratamentos e 4 repetições. O estudo foi realizado em área experimental pertencente à Faculdade de Engenharia Campus de Ilha Solteira - UNESP, localizada no município de Selvíria-MS, em solo originalmente sob vegetação de cerrado e cultivado anteriormente com a cultura do milho. Foram realizadas as seguintes avaliações: população de plantas, matéria seca de plantas, nitrogênio nas folhas e grãos, molibdênio nas folhas e grãos, altura de inserção da primeira vagem, comprimento da primeira vagem, componentes de produção (número de vagens/planta, número de grão/planta, número de grão/vagem e massa de 100 grãos) e rendimento de grãos. A aplicação de Mo via foliar não 2 interfere na produtividade, e a aplicação de doses crescentes de nitrogênio em cobertura proporciona aumento crescente no teor de nitrogênio nas folhas e na produtividade de grãos. Termos para Indexação: Phaseolus vulgaris L., doses de N... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Nitrogen is the nutrient most uptaken by common bean plant, and molybdenum besides its importance to N fixation process, is associated to N metabolism. Thus, this micronutrient lack produces symptoms like those caused by N deficiency. This research had the objective of evaluating, on common bean crop, the effect of N levels application in side dressing (0, 30, 60, 90 and 120 kg ha-1) as well as the leaf application of Mo (0, 80 and 160 g ha-1) in development phases V3 and V4 under no tillage system. The experimental design was the randomized blocks with 30 treatments and 4 repetitions. The research was carried out in Selvíria-MS on soil previously cropped with corn. Stand, dry matter weight, N in leaves and seeds, Mo in leaves and seeds, 1st pod insertion height, 1st pod length, number of pod per plant, number of seed per plant, number of seed per pod, weight of 100 seeds and yield were evaluated. The application of Mo on leaf does not interfere on the productivity. The application of increasing levels of nitrogen in side dressing causes a crescent increase in nitrogen level on leaves and on grains productivity / Mestre

Farmers are always looking for ways to increase yields and profits and no-tillage may be a way to achieve this goal. However, a comprehensive study of the performance of no-tillage yields relative to conventional tillage yields and their net returns is lacking. This study evaluated the potential factors that influence differences in conventional tillage and no-tillage yields and net returns as explained by such factors as time, crop, precipitation, soil texture and geographic region. Data were collected from 442 paired tillage experiments growing corn, soybeans, cotton, oats, wheat and sorghum published in three refereed journals. Data were evaluated using a mixed model and logit model respectively, to evaluate differences in mean yields and downside risk with no-tillage compared to tillage. Sorghum and wheat were found to have higher no-tillage yields relative to tillage. No-tillage was also found to outperform conventional tillage in the southern United States with just the opposite occurring in the northern U.S. A silty soil was also found to reduce no-tillage yields. Several factors were found to decrease the chance of downside risk with no-tillage, they were sorghum, sandy soil, Northern Crescent, Northern Great Plains, Prairie Gateway and Southern Seaboard regions. Two factors that increased the chance of lowered no-tillage yields were increased rainfall and length of use of no-tillage. Differences in mean net returns and downside risk were evaluated using a mixed model and logit model. Results showed that no-tillage was more profitable than conventional tillage in the Mississippi Portal region, but less profitable in the Prairie Gateway. Net returns were lower for no-tillage wheat and soybeans when produced in a clay soil. Cotton grown in sand had higher no-till net returns, but increased rainfall decreased cotton net returns. A logit model showed certain factors decreased the probability of lower no-tillage net returns. There was less downside risk with wheat grown under no-tillage as well as less downside risk in the Southern Seaboard region and when no-tillage was used on a clay soil. There were factors that increased the probability of lower no-tillage net returns; increased precipitation, Northern Great Plains, Prairie Gateway and Basin & Range regions.

This study evaluated the effects of tillage system, rotational tillage sequences, and winter seed burial depth on weed seedling recruitment in irrigated cropping systems. Notill (NT) planting of vegetable crops reduced emergence of hairy nightshade by 77 to 99% and Powell amaranth emergence from 50 to 87% compared to conventional tillage (CT) and planting of crops. Cover crops suppressed weed emergence if soils were undisturbed but not if soils were tilled in the spring. Four years of NT vegetable crops reduced summer annual weed density by 48 to 79% at two sites. Rotational tillage sequences that alternated between NT and CT only reduced summer annual weed density if the shorter season crop of snap beans was paired with CT and sweet corn was paired with NT. Hairy nightshade density decreased by 83 to 90% if NT was paired with the longer season crop of sweet corn. Hairy nightshade seedling recruitment at 30.7 C was more than 15 times greater for seeds buried at 6, 13 and 25 cm than when buried at 1 cm in simulated NT. Recruitment potential was low in March and April but increased to a maximum in May and June. Germination rates for seeds buried at 1 cm were lower and mortality and dormancy greater than for seeds buried from 6 to 25 cm during the winter. Protecting the seeds buried at 1 cm from rainfall during the winter increased seedling recruitment from 0 to 2 of 10 buried seeds, but had a negligible effect on seed mortality and dormancy. Treatment of seeds buried at 25 cm with 1 cm soil temperature reduced recruitment from 4.8 to 2.3 of 10 buried seeds at 33.3 C, but did not significantly increase seed mortality or dormancy. Estimates of seed drift using electronic transponders found that 16% of the seeds at 5 cm moved to within the emergence zone for hairy nightshade. Seed drift coupled with the faster germination rate and lower mortality of seeds buried at 12 cm or below predicts that hairy nightshade recruitment will be optimized when soil is tilled in the spring. / Graduation date: 2005

The use of no-tillage (NT) system has increased in the past few years in South Africa, but its effects on soil physical conditions have not been adequately documented. This study was undertaken to ascertain these effects, as compared to Conventional tillage (CT) system. Several sites were selected in the Bergville and Winterton areas of the midlands of KwaZulu-Natal, and at the Cedara Agricultural Research Station. NT generally increased bulk density in the topsoil and this altered total porosity and poresize distribution. Water retention, organic C and aggregate stability were increased under NT, partly due to the maintenance of the mulch cover on the surface soil. Organic C and aggregate stability were positively correlated with each other. Differences in bulk density between tillage systems with soil depth did not clearly indicate where soil compaction had occurred. Significant differences in soil compaction between treatments were, however, illustrated by changes in soil penetration resistance (SPR), especially at the. 150 mm depth. In addition, depending on the soil type, SPR was greater in the topsoil under NT than CT. It was suggested that conversion from CT to NT was carried out when the topsoil of the CT-fields was structurally poor, due to a previous history of continuous CT. Tractor traffic under CT and repeated tillage when the soil was wet had, in some cases, resulted in the formation of a compacted layer at the depth of cultivation. In clay soils, this has resulted in subsoil compaction. The formation of compacted layers caused major changes to pore size distribution and continuity and this resulted in substantially reduced hydraulic conductivity, infiltration rate,air-filled porosity and air permeability. It was concluded that compacted subsoil layers need to be broken up prior to conversion from CT to NT, and that compaction in the surface soil under NT has occurred and, in some cases, this will be a limitation to crop production. The use of minimum tillage systems should be considered and researched in these cases. / Thesis (M.Sc.)-University of Natal, Pietermaritzurg, 2003.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.