Submitted by Guilherme Constantino Meirelles (gui_meirelles2312@hotmail.com) on 2018-02-01T12:07:44Z No. of bitstreams: 1 001-2018-Guilherme Constantino Meirelles.pdf: 5392903 bytes, checksum: 5c9a1168bbab1257c59ad0f0d9f2dce7 (MD5) / Approved for entry into archive by Fabio Sampaio Rosas null (fabio@dracena.unesp.br) on 2018-02-01T13:02:51Z (GMT) No. of bitstreams: 1 meirelles_gc_me_dra.pdf: 5392903 bytes, checksum: 5c9a1168bbab1257c59ad0f0d9f2dce7 (MD5) / Made available in DSpace on 2018-02-01T13:02:51Z (GMT). No. of bitstreams: 1 meirelles_gc_me_dra.pdf: 5392903 bytes, checksum: 5c9a1168bbab1257c59ad0f0d9f2dce7 (MD5) Previous issue date: 2017-12-07 / Outra / Pró-Reitoria de Pós-Graduação (PROPG UNESP) / A pastagem tem se destacado como principal fonte de alimento para pecuária brasileira pela sua extensa área e baixo custo de produção. A aplicação de nitrogênio na pastagem está associada diretamente com o aumento de produção de matéria seca, bem como incremento na qualidade da forragem, contribuindo na manutenção da capacidade produtiva. O experimento foi realizado no campo experimental da Faculdade de Ciências Agrárias e Tecnológicas, Campus de Dracena, com o objetivo de avaliar fontes nitrogenadas convencionais e com eficiência aumentada na volatilização de amônia e seus efeitos na produção de pastagem de Urochloa decumbens (syn. Brachiaria decumbens). O delineamento experimental foi em blocos ao acaso com quatro repetições, em esquema fatorial 4x2+1. As parcelas constituíam de 4 fontes nitrogenadas (ureia, nitrato de amônia, ureia + NBPT, ureia + B e Cu), com duas doses de nitrogênio (100 e 200 kg ha-1), acrescido um tratamento sem adubação nitrogenada (controle). As doses nitrogenadas foram parceladas em 5 aplicações iguais (20 e 40 kg ha-1), sendo a primeira após o corte de uniformização e as demais após os cortes imediatamente subsequentes. A aplicação das fontes e doses de nitrogênio afetaram a produção acumulada de massa seca e lâminas foliares de capim decumbens no primeiro e segundo ano de condução do experimento. A quantidade de N, P, K, Ca, Mg e S absorvidos foi maior com o aumento das doses de nitrogênio na adubação. No primeiro ano o teor de proteína bruta do capim decumbens aumentou com a aplicação de nitrogênio no sistema, independente da fonte; Os teores de FDN e FDA não alteraram em função das fontes e doses nitrogenadas. No segundo ano aumentaram os teores de FDA e PB em função das doses de nitrogênio independente da fonte utilizada, e o teor de clorofila aumentou com doses maiores de N. A menor eficiência de uso do nitrogênio na produção de massa seca de capim decumbens foi com a utilização de ureia sem revestimento e as fontes nitrato de amônio, ureia + NBPT e ureia + B + Cu não apresentaram diferença significativa; Na avaliação isolada em cada corte a ureia apresentou maior volatilização em relação as fontes nitrato de amônio, ureia + NBPT e ureia + B + Cu; Na volatilização acumulada de amônia, em quatro avaliações, foi em ordem crescente nitrato de amônio = ureia + NBPT < ureia + B + Cu < ureia (sem revestimento). A maior volatilização de amônia ocorreu até o nono dia após a aplicação dos fertilizantes nitrogenados. No segundo ano na volatilização acumulativa ocorreu na seguinte ordem crescente de perdas de amônia nitrato de amônio < ureia + NBPT = ureia +B + Cu < ureia. / Pasture have been the main source of feed for livestock systems in extensive production systems. Nitrogen fertilization is an important management practice in forage systems because it usually increases forage accumulation, nutritive value and persistence of the pasture. The objective of this study was to evaluate the effects of different levels and sources of N fertilizer on ammonia volatilization, herbage accumulation and nutritive value Urochloa decumbens pasture (syn. Brachiaria decumbens). The study was conducted at the Sao Paulo State University - Campus Dracena in 2015 to 2017. The experimental design was in randomized blocks with four replicates, in a factorial scheme 4x2+1. The plots were composed of four nitrogen sources (urea, ammonium nitrate, urea + NBPT, urea + B + Cu) and two nitrogen doses (100 and 200 kg ha-1), plus a treatment without nitrogen (control). The nitrogen doses were divided in five equal applications (20 e 40 kg ha-1), the first one after the cut of uniformization and the others after the immediately subsequent cuts. The application of the different sources and nitrogen doses affected the accumulated dry mass production of the signal grass in the first and second year of the experiment. The application of the different sources and nitrogen levels affected the accumulated dry mass production of leaf blade. The amount of N, P, K, Ca, Mg and S absorbed was higher with increasing levels of nitrogen at fertilization. In the first year the crude protein (CP) content of the signal grass increased with the application of nitrogen in the system, regardless of the source; The concentration of neutral detergent fiber (NDF) and acid detergent fiber (ADF) did not change due to nitrogen sources and doses. In the second year, the levels of ADF and CP increased as a function of the doses of nitrogen independent of the source used and the chlorophyll content increased with greater levels of N. The lower efficiency of nitrogen use in dry mass production of signal grass was with the use of uncoated urea and the sources of ammonium nitrate, urea + NBPT and urea + B + Cu did not present significant difference; In the isolated evaluation in each section the urea presented greater volatilization in relation to the sources of ammonium nitrate, urea + NBPT and urea B + Cu; In the accumulated volatilization of ammonia, in four evaluations, it was in increasing order ammonium nitrate = urea + NBPT < urea + B + Cu < urea (without coating). The highest volatilization of ammonia occurred until the ninth day after the application of nitrogen fertilizers. In the second year in the cumulative volatilization occurred in the following increasing order of ammonia losses ammonium nitrate < urea + NBPT = urea + B + Cu < urea.

Orientador: Reges Heinrichs / Resumo: A pastagem tem se destacado como principal fonte de alimento para pecuária brasileira pela sua extensa área e baixo custo de produção. A aplicação de nitrogênio na pastagem está associada diretamente com o aumento de produção de matéria seca, bem como incremento na qualidade da forragem, contribuindo na manutenção da capacidade produtiva. O experimento foi realizado no campo experimental da Faculdade de Ciências Agrárias e Tecnológicas, Campus de Dracena, com o objetivo de avaliar fontes nitrogenadas convencionais e com eficiência aumentada na volatilização de amônia e seus efeitos na produção de pastagem de Urochloa decumbens (syn. Brachiaria decumbens). O delineamento experimental foi em blocos ao acaso com quatro repetições, em esquema fatorial 4x2+1. As parcelas constituíam de 4 fontes nitrogenadas (ureia, nitrato de amônia, ureia + NBPT, ureia + B e Cu), com duas doses de nitrogênio (100 e 200 kg ha-1), acrescido um tratamento sem adubação nitrogenada (controle). As doses nitrogenadas foram parceladas em 5 aplicações iguais (20 e 40 kg ha-1), sendo a primeira após o corte de uniformização e as demais após os cortes imediatamente subsequentes. A aplicação das fontes e doses de nitrogênio afetaram a produção acumulada de massa seca e lâminas foliares de capim decumbens no primeiro e segundo ano de condução do experimento. A quantidade de N, P, K, Ca, Mg e S absorvidos foi maior com o aumento das doses de nitrogênio na adubação. No primeiro ano o teor de proteína bruta do c... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

The thesis is divided in to five chapters. Chapter I: Synthesis of New thiolevomannosan derivatives In this chapter, a general and efficient method for the synthesis of conformationally locked thiosugars has been discussed. An unprecedented synthesis of a novel thioorthoester and its synthetic utility in glycosylation has been demonstrated. Chapter II: Studies on -Mannosidase Inhibitors The synthesis and evaluation of novel, conformationally locked glycomimic, thiolevomannosan and its analogs sulfoxide and sulfone starting from readily available D-mannose is discussed in this chapter. This is the first report of thiosugar derivatives with enhanced potency compared to kifunensine. Docking and biochemical studies have been discussed. Chapter III: Studies on Novel Cyclic Tetraselenides of Mannose In this chapter, the syntheses and structural properties of novel cyclic tetraselenides starting from mannose have been discussed. These tetraselenides are the first of their kind where all four selenium atoms are arranged in a cyclic manner as the backbone of mannose. X-ray structures have been reported for the tetraselenides. Chapter IV: Novel Chalcogenides of Uridine and Thymidine: Synthesis and Applications An efficient and simple method to synthesise disulfides and diselenides of thymidine and uridine derivatives has been demonstrated in this chapter. The utility of these disulfides in various ring opening reactions as well in Michael addition reactions has been demonstrated. Chapter V: Studies on New, Potent Urease Inhibitors In this chapter, a facile one-pot synthesis of thio and selenourea derivatives under mild conditions by the reaction of amines and commercially available Viehe’s iminium salt in the presence of benzyltriethylammonium tetrathiomolybdate as sulfur transfer reagent and tetraethylammonium tetraselenotungstate as selenium transfer reagent has been discussed. A few of the urea derivatives have shown potent inhibitor activity in the nanomolar range for jackbean urease.

The major land use in New Zealand is pastoral farming of sheep and cattle. In intensively grazed dairy-pasture systems, animals graze on nitrogen (N)-rich legume-based pastures, but do not efficiently utilize the N they ingest. On average only 10.5% of the N in forage-based animal feed is converted into milk and the remainder is excreted in dung and urine. In the pastures, a cow urine patch can typically contain up to 1000 kg N ha-1. Nitrogen input, either in the form of cow urine or fertilizer, often exceeds immediate plant requirements and hence is susceptible to losses as ammonia (NH3) volatilisation and nitrous oxide (N2O) emissions and removal in drainage water through nitrate (NO3-) leaching. This loss of N from grazed pastures causes detrimental environmental impacts in the form of acidification and eutrophication of the soil and water bodies, global warming, destruction of stratospheric ozone, and NO3- toxicity. Various approaches have been attempted to mitigate the economic and environmental impacts of N losses. One such approach is the use of Urease (UIs) and Nitrification (NIs) inhibitors. There have been extensive studies on the value of UIs in arable farming and NIs in grazed pastures. However, only limited work on the impact of UI and NI alone and in combination in influencing the N dynamics, and thus mitigating N gaseous losses from pastures, has been conducted. This thesis examines the impact of UI (Agrotain; N-(n-butyl) thiophosphoric triamide) and NI (Dicyandiamide, commonly known as DCD), when applied alone or in combination to cow urine and urea fertiliser, on N losses through NH3 and N2O emissions and NO3- leaching, and on herbage production under glasshouse conditions and a field-plot study. The degradation rate of DCD, and its effect on nitrification and on N2O emissions from four soils varying in their physical and chemical properties was also examined under laboratory incubations. The results from the field-plot study were then used to predict the effect of DCD on N2O emissions reductions from urine by adapting the process-based NZ-DNDC model. Both NH3 and N2O emissions have common sources in agriculture. Therefore, chambers were adapted to measure their emissions simultaneously using active and passive gas sampling. Active sampling involved continuous air flow and the use of acid (0.05 M H2SO4 and 2% H3BO3) traps for NH3 measurements and passive sampling involved collecting three gas samples over a one-hour period from a static chamber used for N2O emissions. The first glasshouse experiment used UI with urine or urea to assess its effect on NH3 and N2O emissions, changes in soil mineral-N and N uptake by pasture plants. The UI treatments also involved two commercial products, Sustain Yellow (urea coated with Agrotain and elemental S) and Sustain Green (urea coated with Agrotain). The use of UI effectively decreased total NH3 emissions, as well as delaying the time of maximum NH3 emissions from both urea (600 kg N ha-1) and urine (476 kg N ha-1) by 27% and 22%, respectively. The UI-induced decrease in NH3 volatilization ranged from 42-48% when urea was applied @ 100 kg N ha-1. Urease inhibitor was also effective in decreasing N2O emissions significantly from urine and urea applied @ 100 kg N ha-1. The addition of UI increased dry matter yield by 13-19% as compared to the urea-alone treatment. In the second glasshouse study, NI (DCD) was added @ 25 kg ha-1 to urea (@ 25, 50 and 75 kg N ha-1) and urine (@ 144, 290 and 570 kg N ha-1) applied at different rates. Addition of DCD reduced N2O emissions from both urea and urine and NO3- leaching from urine. Dicyandiamide reduced N2O emissions by 34-93% from the added urea and 33-80% from the added urine. However, its use increased the amount of ammonium (NH4+) present in the soil by 3 to 13% both in the urea and urine treatments, and this NH4+ was susceptible to leaching and volatilisation losses. The addition of DCD, however, resulted in a 60-65% reduction in NO3- leaching from urine applied to pasture soil cores. It also caused a significant reduction in NO3- -induced cation leaching. Leaching of K+, Mg+2 and Ca+2 ions was reduced by 36-42%, 33-50% and 72%, respectively, with DCD applied to cattle urine (290 and 570 kg N ha-1). The combined use of UI and NI was more effective in controlling N gaseous losses than using them individually. The combination of UI and NI retarded NH3 emissions by 70% in the urea treatment and by 4% in the urine treatment (field-plot study). It also considerably reduced N2O emissions (50-51%) following the application of urea and urine (field-plot study) to pasture soil. With the combined inhibitors, there was a 14 and 38% increase in herbage yield from added urea and urine (field-plot study), respectively. A laboratory incubation experiment was undertaken to study the effect of soil types and the rate of DCD application on the degradation kinetics of DCD. The rate of degradation of DCD varied among the four soils studied. The degradation was slowest (half-life period of 6 to 11 days) in an allophanic soil with a high concentration of organic matter. The effectiveness of DCD in inhibiting nitrification also varied depending on the nature and amount of soil organic matter and clay content. The maximum inhibition was observed in a soil with low organic matter and high clay content. Finally, 'NZ-DNDC', a process-based model, was adapted and used to simulate the effect of DCD on emissions reduction using DCD inhibition values that vary according to different soil types. This model effectively simulated the effect of DCD on N2O emissions reductions in Tokomaru silt loam following urine application. However, more field data are required from a range of pasture soils with contrasting amount of soil organic matter and clay content under differing climatic conditions to further test this model modification to predict emission-reductions with DCD application in different soil types.