• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 445
  • 323
  • 36
  • 31
  • 25
  • 16
  • 16
  • 9
  • 7
  • 7
  • 6
  • 4
  • 3
  • 3
  • 2
  • Tagged with
  • 1106
  • 327
  • 157
  • 138
  • 116
  • 98
  • 92
  • 82
  • 81
  • 76
  • 76
  • 73
  • 71
  • 60
  • 59
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Efeito da suplementação com fitase sobre o desempenho e digestibilidade de nutrientes para frangos de corte

Santos, Fabiana Ramos dos [UNESP] 24 March 2005 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:28:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-03-24Bitstream added on 2014-06-13T20:37:10Z : No. of bitstreams: 1 santos_fr_me_jab.pdf: 455540 bytes, checksum: 07526b538f1fb8c52fc7db3eeeb0e2e0 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Dois ensaios metabólicos e um ensaio de desempenho foram conduzidos para avaliar o efeito da suplementação com fitase (Phyzyme XP 5000G®) em dietas com redução nos níveis de EMA, PB, Lis, Ca e Pd sobre digestibilidade de nutrientes e desempenho de frangos de corte. Em todos os ensaios, foi utilizado um delineamento inteiramente casualizado em esquema fatorial 3 x 2 (três dietas com redução de nutrientes (controles negativos (CN), com e sem enzima) e um controle positivo (CP). Para o ensaio de desempenho foram utilizadas sete repetições de 40 aves por unidade experimental e para o de digestibilidade, seis repetições de 15 aves cada. A fitase foi suplementada nos níveis de 500, 750 e 1000 U de fitase nos CN1, CN2 e CN3, respectivamente. Os ensaios metabólicos foram conduzidos com frangos dos 14 a 21 e 28 a 35 dias de idade. Foram utilizados os métodos: coleta parcial de excretas e digesta ileal, utilizando-se cinza ácida insolúvel como indicador indigestível. Dos 14 aos 21 dias de idade, a redução nos níveis nutricionais das dietas resultou em EMA, ED, CDMS e CDAA (exceto para o CD Val, Iso, Tir, Fen e Leu) inferiores aos obtidos com a dieta CP. A interação (P<0,05) obtida para ED, CDIPB e CDAA mostrou que a adição de fitase melhorou estes parâmetros nos CN1 e CN2. Para a fase de crescimento, foram determinadas EMA e ED menores que os do CP apenas nos CN2 e CN3. O CDAA das dietas CN sem e com adição de fitase foram superiores aos do CP, exceto para Arg, Cis e His. Houve interação (P<0,05) para a EMA, ED e CDMS, sendo a fitase eficiente nos CN2 e CN3. A suplementação com fitase aumentou em média o CDIPB em 5% e o CDAA em 2,89%. A adição de fitase nos CN aumentou (P<0,05) o CD de todos os minerais avaliados. Aos 21 e 42 dias de idade, a redução de nutrientes na dieta causou um efeito negativo sobre o ganho de peso, consumo de ração e rendimento de carcaça... / Two digestibility trials and one performance trial were conducted to study the effect of supplementation of phytase in diets formulated with reduction in the levels of ME, CP, Lys, Ca and P, on the digestibility of nutrients and performance of broiler chicks. The treatmeants consisted of a factorial arrangement 3 x 2 (three levels of nutrient reduction (Negatives Controls . NC), with and without enzyme supplementation) and one positive control (PC). In the performance trial was utilized seven replicates of 40 birds per unity experimental and in digestibility trial, six replicates with 15 birds each. The phytase utilized was the Phyzyme XP 5000 G supplemented at 500, 750 and 1000 U of phytase in the NC1, NC2 and NC3, respectively. The digestibility trials were conducted from 14 to 21 and 28 to 35 days of age. Were utilized the metods of partial excreta and ileal digest collection. The acid insoluble ash were used as indigestible marker. In 14 to 21 days of age, the nutritional reduction of diets resulted in lower ME, DE, DCDM and DCAA (except for of Val, Iso, Tir, Phe and Leu digestibility) compared to PC diet. The interaction (P<0,05) for DE, DCIC and DCAA showed that the phytase supplementation on the NC1 and NC2 diets increased these parameters. In the 28 to 35 days, ME and DE were lower compared to CP only of NC2 and NC3. The DCAA of the NC without and with phytase supplementation were superior of the diet PC, except for Arg, Cis and His. There was interaction (P<0,05) for ME, DE, DCDM and the phytase addition on the NC2 and NC3 diets increased these coefficients. The phytase addition increased the DCICP at 5 % and DCAA in 2,89%. The phytase supplementation on the NC increased the digestibility of the all minerals in study. At 21 and 42 days, the reduction of nutrients caused a negative effect on weight gain, feed intake and carcass yield... (complete abstract, access undermentioned eletronic address)
182

Crescimento e acúmulo de nutrientes em quiabeiro ‘Santa Cruz 47'

Galati, Vanessa Cury [UNESP] 29 July 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:28:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-07-29Bitstream added on 2014-06-13T19:16:29Z : No. of bitstreams: 1 galati_vc_me_jabo.pdf: 170793 bytes, checksum: d0fabeb3194e3b8aa6988a1e309db1f7 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O experimento foi realizado de 14 de janeiro a 14 de maio de 2009, na UNESP Câmpus de Jaboticabal, SP, com o objetivo de quantificar o crescimento da planta e o acúmulo de macro e micronutrientes do quiabeiro, no decorrer do ciclo, e obter equações que melhores os representem. A cv. Santa Cruz 47 foi semeada diretamente nos sulcos abertos no solo, colocando-se três sementes a uma profundidade de 3 cm e espaçamento de 1 x 0,2 m. O desbaste foi realizado 15 dias após semeadura (DAS). No decorrer do ciclo, realizaram-se coletas aleatórias de plantas com intervalos de quinze dias. As médias foram ajustadas às equações de regressão polinomial e de parâmetros não lineares. Aos 50 DAS houve um elevado incremento no acúmulo de matéria seca nas partes das plantas. Na colheita final, 120 DAS, as folhas, a haste e os frutos representaram 21; 71 e 8%, respectivamente, da matéria seca total da planta. Na cultura do quiabeiro o acúmulo de macro e micronutrientes foi maior na fase reprodutiva. A sequência decrescente de acúmulo de nutrientes pelo quiabeiro foi K, Ca, N, Mg, P, S, Fe, B, Mn, Zn e Cu, em quantidades equivalentes à 6.002,8; 4.733,8; 2.930,8; 1.196,3; 473,7; 436,2; 49,82; 10,4; 7,1; 7,1 e 1,52 mg planta-1. As quantidades exportadas pela cultura foram 146,5; 23,7; 300,1; 236,7; 59,8 e 21,8 kg ha-1 de N, P, K, Ca, Mg e S, respectivamente, e de 520,0; 76,0; 2.491,0; 355,0 e 355,0 g ha-1 de B, Cu, Fe, Mn e Zn, respectivamente / The experiment was carried out at Jaboticabal, SP, Brazil, from January 14th to May 14th, 2009. The objective of this project was to quantify the okra crop’s growth and macro and micronutrients accumulation during its life-cycle obtaining equations that best represent it. The cv. Santa Cruz 47 was sowed into furrows in the soil, placing three seeds to a depth of about 3 cm arranged in a spacing of 1 x 0,2 m. The cleaning had been done by 15 days after sowing (DAS). During the life-cycle were colected random samples of plants at 15 days intervals. The means were adjusted to polynomial regression equations set of non-linear parameters. At 50 DAS there has been a dry matter increase in plants’ parts. At the final harvest, 120 DAS, the leaves, stems and fruits accounted for 21, 71 and 8%, respectively, from the total plant dry matter. In the okra crop the macro and micronutrients accumulation was higher in the reproductive period. The decreasing sequence of nutrient accumulation was K, Ca, N, Mg, P, Fe, B, Mn, Zn and Cu equivalent to 6,002.8; 4,733.8; 2,930.8; 1,196.3; 473.7; 436.2; 49.8; 10.4; 7.1; 7.1 e 1.5 mg plant-1. The quantity accumulated of culture were 146.5; 23.7; 300.1; 236.7; 59.8 e 21.8 kg ha-1 of N, P, K, Ca, Mg e S, respectively, and 520.0; 76.0; 2,491.0; 355.0 e 355.0 de B, Cu, Fe, Mn e Zn, respectively
183

Curva de crescimento e exportação de nutrientes e sódio por frutos de mangueira Palmer, Haden e Tommy Atkins

Souza, Flávia Vieira de [UNESP] 26 June 2007 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:23:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-06-26Bitstream added on 2014-06-13T18:06:57Z : No. of bitstreams: 1 souza_fv_me_jabo.pdf: 322447 bytes, checksum: 01e355ed4d91b7c8dd1924be57a0498b (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Objetivou-se com o presente estudo determinar a curva de crescimento e a extração de nutrientes e sódio por frutos de mangueira Haden, Palmer e Tommy Atkins. O estudo foi conduzido em uma área de produção comercial de mangas em Janaúba-MG. O delineamento experimental para cada variedade de manga foi inteiramente casualizado, com cinco repetições e os tratamentos corresponderam as épocas de amostragem das panículas . Cada unidade experimental foi composta por cinco plantas. Durante o pleno florescimento, foram demarcadas seis panículas por planta, iniciando a coleta quando os frutos atingiram o estádio de chumbinho, aproximadamente cinco dias após a antese, e finalizando quando os frutos atingiram o ponto de colheita, totalizando 15, 19 e 19 amostragens, para as variedades Haden, Palmer e Tommy Atkins, respectivamente. Após cada coleta, determinaram-se a massa fresca, massa seca e os teores de nutrientes e sódio . A variedade Haden atingiu o ponto de colheita aos 92 dias após a antese, seguida pela variedade Tommy Atkins aos 115 dias e Palmer aos 117 dias. As curvas de crescimento dos frutos para as três variedades de mangueira apresentaram padrão sigmoidal. A ordem decrescente de extração de nutrientes e sódio pelos frutos da mangueira Haden foi: K>N>Ca>Mg>S>P>Mn>Fe>Na>B>Zn>Cu. Na mangueira variedade Palmer: K>N>Ca>P>Mg>S>Mn>Na>Fe>Cu>B>Zn e na mangueira Tommy Atkins foi: K>N>Ca>P>Mg>S>Mn>Fe>Na>Cu>B>Zn. Os nutrientes extraídos em maiores quantidades pelas três variedades foram: K>N>Ca. A variedade Haden extrai maior quantidade de todos os nutrientes, exceto o P. / It was aimed at with the present study determinate the growth curve and extraction of nutrients and sodium for mango fruits Haden, Palmer and Tommy Atkins. The study was carried in the area of commercial production de mango in Janaúba – MG. The experimental design for wich varietie of mango was completely randomized, with five replications and the treatments corresponded the times of sampling of the panicles. Each experimental unit was composed for five plants. During the full bloom, they had been demarcated six panicles for plant, initiating the collection five days after anthesis, and finishing when the fruits had reached the point of harvest, totalizing 15, 19 and 19 samplings, for the varieties Haden, Palmer and Tommy Atkins, respectively. After each collection, fresh mass, dry mass and the concentrations of nutrients and sodium the fruits had been determined it. The Haden variety after reached the point of harvest to the 92 days anthesis, followed for the variety Tommy Atkins to the 115 days and Palmer to the 118 days. The growth curves of the fruits for the three varieties presented pattern sigmoid. Rate of nutrients and sodium extraction in decreasing order for the fruits of the varieties Hadem was: K>N>Ca>Mg>S>P>Mn>Fe>Na>B>Zn>Cu; in the variety Palmer: K>N>Ca>P>Mg>S>Mn>Na>Fe>Cu>B>Zn and in the variety Tommy Atkins: K>N>Ca>P>Mg>S>Mn>Fe>Na>Cu>B>Zn. The extracted nutrients in larger amounts for the three varieties were: K>N>Ca. The variety Haden extracts larger amount of all the nutrients, except the P.
184

Caracterização de componentes inorgânicos em suplementos nutricionais pelo método de análise por ativação com nêutrons

REIS, ROGERIO A. de S. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:51:31Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:00Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
185

Caracterização morfológica e nutricional em diferentes estádios fenológicos da mandioca de mesa IAC 576-70 sob deficiência hídrica / Morphological and nutrition characterization at different phenological stages of sweet cassava IAC 576-70 under water stress

Zanetti, Samara [UNESP] 27 July 2016 (has links)
Submitted by Samara Zanetti (samarazanetti@hotmail.com) on 2016-11-09T17:14:52Z No. of bitstreams: 1 Dissertação final.pdf: 1425092 bytes, checksum: 77869aab1560a58921ae52b649d3da9d (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO null (luizaromanetto@hotmail.com) on 2016-11-16T12:20:36Z (GMT) No. of bitstreams: 1 zanetti_s_me_bot.pdf: 1425092 bytes, checksum: 77869aab1560a58921ae52b649d3da9d (MD5) / Made available in DSpace on 2016-11-16T12:20:36Z (GMT). No. of bitstreams: 1 zanetti_s_me_bot.pdf: 1425092 bytes, checksum: 77869aab1560a58921ae52b649d3da9d (MD5) Previous issue date: 2016-07-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O trabalho teve como objetivo avaliar as respostas morfológicas, anatômicas e nutricionais da mandioca de mesa em diferentes fases de crescimento da cultura sob condições de déficit hídrico. O experimento foi conduzido por um ano sob cultivo protegido no Faculdade de Ciências Agronômicas, Campus de Botucatu, em delineamento experimental inteiramente casualizado, com esquema fatorial 3 x 3, constituído de três fases de crescimento (90 a 180 DAP; 180 a 270 DAP e 270 a 360 DAP) da cultivar de mandioca de mesa IAC 576-70 e três tensões de água no solo ( -10, -40 e -70 kPa). As manivas-sementes com 5 a 7 gemas foram plantadas em caixas com capacidade de 500 L, sendo irrigadas diariamente, mantendo o solo na capacidade de campo até o início das fases. Aos 0, 20, 40, 60 e 80 dias após o início do déficit foram avaliados a altura de planta, o diâmetro do caule, o número de folhas por planta, a área foliar total e o índice de área foliar. As folhas da mandioca foram analisadas quanto a sua estrutura anatômica aos 150 dias após o plantio. Foram realizadas avaliações nutricionais aos 180, 270 e 360 dias após o plantio. No momento da colheita avaliou-se a massa da matéria seca da parte aérea (folhas + haste), da cepa, das raízes tuberosas e fibrosas; o comprimento e diâmetro das raízes tuberosas; o número de raízes; o índice de colheita; a razão de área foliar e a produtividade. As fases de crescimento 90 a 180 DAP e 270 a 360 dias após o plantio (DAP) foram influenciadas pelas tensões de água no solo, proporcionando reduções em todas as variáveis morfológicas e nos componentes de produção. A anatomia das folhas apresentou modificações como diminuição das espessuras do mesofilo, do parênquima lacunoso, da epiderme abaxial, e do número de elemento de vasos, e aumento da espessura e diâmetro dos elementos de vaso. Houve diminuição no teor de K nas fases de 90 a 180 e 270 a 360 DAP e aumento de P e Mg nas três fases, e Fe e Zn aos 90 a 180 DAP. A produtividade final das raízes tuberosas foi afetada pelas tensões de água no solo (-40 e -70 kPa) nas fases de 90 a 180 e 270 a 360 após o plantio. / This research aimed to evaluate the morphological, anatomical and nutritional responses of sweet cassava in different growth stages of the crop under water deficit. The experiment was carried out for a year in a greenhouse at the Faculty of Agricultural Sciences, Botucatu, in a completely randomized design in factorial scheme 3 x 3, consisting of three growth stages (90-180 DAP, 180-270 DAP and 270-360 DAP) of cultivating sweet cassava IAC 576-70 and three water tension in the soil (-10, -40 and -70 kPa). The stem cuttings with 5-7 nodes of the cultivar IAC 576-70 were planted in boxes with 500 liters capacity, keeping soil moisture at field capacity until the beginning of the phases. At 0, 20, 40, 60 and 80 days after the beginning of the deficit were measured the plant height, stem diameter, number of leaves per plant, total leaf area and leaf area index. Cassava leaves were analyzed for their anatomical structure at 150 days after planting. It were nutritional evaluations performed at 180, 270 and 360 days after planting, and at harvest evaluated the dry matter of the shoot (leaves + stem), the strain of tuberous and fibrous roots; the length and diameter of the tuberous roots; the number of roots; harvest index; the leaf area ratio and productivity. The growth phases 90 to 180 and 270 to 360 days after planting (DAP) were influenced by the water tension in the soil, providing reductions in all morphological variables and production components. The anatomy of the leaves showed changes as the decrease of the thickness of mesophyll, of the spongy parenchyma, epidermal abaxial, and of the vessels element number and increasing the thickness and diameter of vessel elements. There was a decrease in K content in phases 90180 and 270-360 DAP and increase of P and Mg in three phases, and Fe and Zn to 90-180 DAP. The final yield of tuberous roots were affected by the tensions in water (-40 to -70 kPa) in the phases 90-180 and 270-360 after planting.
186

Acúmulo de nutrientes e desempenho agronômico do pimenteiro (Capsicum Annum L.) em função dos métodos de enxertia /

Silva, Ewerton Gasparetto da, 1985. January 2012 (has links)
Orientador: Rumy Goto / Banca: Dirceu Maximino Fernandes / Banca: Roberto Botelho Ferraz Branco / Resumo: Avaliou-se a produtividade, a concentração e a quantidade de nutrientes em plantas enxertadas pelos métodos contato bisel, garfagem por fenda cheia e encostia, comparadas as plantas não enxertadas (pé-franco), cultivadas em ambiente protegido. O delineamento experimental foi em blocos ao acaso com quarto tratamentos e cinco repetições, com 12 plantas por parcela. O híbrido e o porta-enxerto utilizados foram o AF 7125 e AF 8253 respectivamente. Avaliaram-se as plantas quanto à altura da primeira bifurcação, altura das plantas, características dos frutos (comprimento, diâmetro e espessura), produção dos frutos em sete colheitas, massa da matéria seca da parte vegetativa (PV) e dos frutos (FR). Realizaram-se as análises químicas em uma planta por parcela aos 35, 85, 112 e 143 dias após transplante, para determinar a concentração e a quantidade de nutrientes absorvidos pelas plantas enxertadas e não enxertadas. As plantas enxertadas e não enxertadas tiveram desempenho agronômico semelhante. A absorção de nutrientes foi semelhante entre as plantas enxertadas e não enxertadas (pé-franco), não sendo observado nenhum tipo de impedimento de transporte de nutrientes ocasionados pela enxertia ou pelo porta-enxerto que pudesse prejudicar no desenvolvimento das plantas enxertadas durante o ciclo / Abstract: It was evaluated the productivity, concentration and amount of nutrients in plants grafted by contact methods bevel, by grafting and cleft grafting, compared to the non-grafted plants (ungrafted), grown in a greenhouse. The experimental design was randomized blocks with four treatments and five replicates of 12 plants per plot. The hybrid and the rootstock used were AF 7125 AF and 8253 respectively. Plants were evaluated for height of first fork, plant height, fruit characteristics (length, diameter and thickness), fruit production in seven crops, dry matter of vegetative parts (PV) and fruit (FR) . Analyzes were carried out in a chemical plant plots with 35, 85, 112 and 143 days after transplant to determine the concentration and nutrient uptake by the grafted and non-grafted. The non-grafted and grafted plants had similar agronomic performance. Nutrient uptake was similar between the grafted and not grafted (ungrafted), and there was no impediment of any kind of transport of nutrients caused by the graft or the rootstock that would undermine the development of grafted plants during the cycle / Mestre
187

Morphology and mineral content of cowpea lines in response to planting date and zinc application rate

Mfeka, Nonkululeko January 2017 (has links)
Thesis (MTech (Agriculture))--Cape Peninsula University of Technology, 2017. / Cowpea (Vigna unguiculata (L.) Walp) is an important grain and fodder legume grown around the world. It is a dual purpose grain legume crop, providing food for man and livestock. Cowpea is identified as a potential crop to diversify food production, minimize production input by improving soil fertility and improve micronutrients of seed, therefore, improving human nutrition. There is limited information available on cowpea production and suitable agronomic practices including planting date to best suit different environmental conditions in South Africa. The objective of this study was therefore to i) evaluate two soil types (sandy and clay soil) and its effect on cowpea, yield components and mineral composition, ii) the effect of different planting date and iii) assess the effect of zinc fertilizer application rate on vegetative, reproductive parameters and mineral content of cowpea seed. A field trial was conducted in Agricultural Research Council (ARC), in two locations Nietvoorbij (clay loam soil) and Bien Donne’ (sandy soil) during the 2015 summer planting season. The trial layout was conducted in a randomised complete block design (RCBD) with five replicates. The factors of the study include three cowpea lines: Cowpea Veg1, M217 and Qukawa with zinc application rate of (0, 15 and 30 kg/ha) through soil application and two planting date (2 October and 2 November 2015). The following agronomic variables were collected, in both locations: germination rate, number of leaves, number of branches, plant height, number of seed per pod, number of pods per plant, pod length, pods per treatment, pod weight, 100 seed weight, morphological traits, moisture content and seed mineral content. Vegetative data was collected on a fourth-night basis on six middle plants per treatment and reproductive parameters were taken after harvest. The variables were subjected to ANOVA using software SAS (2012). Treatments were tested at 5% level of significance and differences between treatments were separated using LSD and DMRT of the SAS 2012 test. The results indicated that vegetative and reproductive parameters measured varied significantly among cowpea lines in each location and across locations due to different cowpea lines and soil type. Line Cowpea Veg1 and Qukawa were the best performing line in both vegetative and yield parameters across the two planting dates in 2015. These lines significantly obtained higher plant height than line M217. Yield and yield parameters were significantly affected by cowpea line. Qukawa obtained the highest seed yield at Bien Donne’ with a mean of 1184.2 kg/ha and seed yield of 686.25 kg/ha for Cowpea Veg1 at Nietvoorbij. The second planting date (2 November 2015) improved germination of plants across the two locations, therefore improving vegetative growth. Zinc (Zn) fertilizer significantly improved plant height across all treatments. An inconsistent response to yield parameters due to Zn application rate was observed. However, though not significant, Zn application of 15 kg/ha increased most of the measured parameters. It was concluded that line Cowpea Veg1 and Qukawa were the best performing lines. The second planting date (2 November) increase germination rate for both locations. It is therefore, recommended that future research should evaluate Zn fertilizer time of application.
188

Functional role of ammonium and nitrate in regulating transpiration for mass-flow acquisition of nutrients in Phaseolus vulgaris L.

Naku, Mandilakhe January 2017 (has links)
Thesis (MTech (Horticulture))--Cape Peninsula University of Technology, 2017 / Transpiration serves in leaf cooling, maintaining turgor pressure, promoting xylem transport of nutrient solutes from roots to shoots and delivering mobile soil nutrients to root surfaces. Soil availability of nitrogen can modulate transpiration rates, consequently powering nutrient delivery to the root surfaces (‗mass-flow'). Although such knowledge on N-regulation of transpiration is available, it remains unknown, however, whether it is NO3- or NH4+ that regulates transpiration. Given that both nitrogen forms co-occur in soils, it is not known how they interact at varying ratios in modulating stomatal behaviour. To test the functional role of NO3- and NH4+ in regulating water fluxes for mass-flow nutrient acquisition, P. vulgaris L. plants were grown with NO3- or NH4+ placed at one of four distances behind a nylon mesh, which prevented direct root access to nitrogen, whilst control plants intercepted the nitrogen source (Chapter 3). Day- and night-time stomatal conductance and transpiration, measured using Infra-Red Gas Analyser (IRGA) declined in NO3- fed plants with the increased distance behind a nylon mesh, with maximum water fluxes at the closest distance (ca. 0 mm), demonstrating a regulatory role of NO3- on stomata closure. An opposite trend was displayed by NH4+ -fed plants, which indicated the incapacity of NH4+ to down-regulate water fluxes and ammoniacal syndrome at high concentrations. To test how different [NO3-] and [NH4+] regulate day- and night-time stomatal conductance and transpiration (Chapter 4), P. vulgaris was fed with six concentrations (0, 0.25, 0.5, 1, 2, 4 and 8 mM) of each nitrogen form. A biphasic trend emerged, as postulated in previous studies (Wilkinson et al., 2007; Matimati et al., 2013), characterized by an increase in stomatal conductance and transpiration as [NO3-] increased, attaining a maximum before declining with higher [NO3-]. Plants displayed 2-fold higher photosynthetic rates, 2.2-fold higher stomatal conductance and 2.3-fold higher transpiration rates at 4 mM than at 0.25 mM of [NO3-]. The lowest [NO3-] up-regulated night-time stomatal conductance and transpiration, indicating that NO3- -fed plants opened their stomata at night-time, but reduced night-time water loss at higher [NO3-]. NH4+-fed plants had the incapacity to regulate day- and night-time water fluxes, but rather displayed wilting and stress known as ‗ammoniacal syndrome'. Thus, under NO3- deprived soil conditions P. vulgaris may be opportunistic in their water uptake, transpiring more when water is available in order to draw nutrients through ‗mass-flow'. This thesis explored and confirmed the functional role of NO3- in regulating day- and night-time water fluxes as a mechanism for increasing ‗mass-flow' acquisition of N and possibly other nutrients, signalling a down-regulation of day-time and night-time water fluxes when [NO3-] is replete (Chapter 3 & 4). Where both NO3- and NH4+ are present in soils, it is the [NO3-] and not [NH4+] that regulated stomatal conductance and transpiration. Since organic nitrogen forms such as amino acids also occur in soils, there is a need for further work on their role in stomatal behaviour. Using amino acids laced with 15N isotopes as a nitrogen source can allow their acquisition and role on stomatal behaviour to be discovered. Current trends in research are focussed around developing real-time in-situ sensing of soil nitrogen status to promote enhanced nitrogen and water use efficiency in agricultural systems. This thesis provides the vital literature on stomatal regulation by [NO3-].
189

Crescimento das macrófitas aquáticas flutuantes Eichhornia crassipes (Mart.) Solms, Pistia stratiotes L. e Salvinia molesta (Mitchell) em diferentes concentrações de nutrientes /

Pistori, Raquel Eduarda Trevisan. January 2009 (has links)
Resumo: Esta tese esta organizada em dois capítulos. O capítulo I testou a hipótese de que o crescimento de Eichhornia crassipes, Pistia stratiotes e Salvinia molesta esta relacionado com a absorção de fosfato e de nitrogênio. Foi avaliado o efeito de diferentes concentrações de nutrientes sobre a taxa de crescimento e de absorção de ortofosfato (PPO4) e nitrogênio inorgânico total (NIT) em E. crassipes, P. stratiotes e S. molesta. As três espécies, quando cultivadas em baixa concentração de nutrientes apresentaram as maiores taxas de absorção tanto de P-PO4 quanto de NIT no período entre 0-5 dias, diferente do que ocorreu quando cultivadas em alta concentração, na qual as maiores taxas de absorção do P-PO4 ocorreram no período entre 0-5 dias e as maiores taxas de absorção de NIT para P. stratiotes ocorreram no período entre 5-10 dias e para E. crassipes e S. molesta no período entre 10-15 dias. Em baixa concentração, S. molesta obteve um ganho de massa 12,8 vezes menor que E. crassipes e 1,3 vezes menor que P. stratiotes e sua taxa de absorção de PPO4 no mesmo período foi semelhante a de E. crassipes e P. stratiotes. Padrão semelhante também foi observado em alta concentração, entretanto, apesar de apresentar maior taxa de absorção, S. molesta foi a espécie menos eficiente na remoção de nutrientes e a que menos estocou N e P, devido ao menor ganho de biomassa. E. crassipes e P. stratiotes apresentam crescimento vertical, o que favorece o maior ganho de biomassa e conseqüentemente maior taxa de remoção de nutrientes e estoque de N e P em sua biomassa. Os resultados permitem concluir que na aplicação para tratamento em wetlands, S. molesta, apesar de apresentar maior taxa de absorção pode ser menos eficiente. O capítulo II teve como objetivo testar o efeito de diferentes concentrações de fosfato na água sobre o crescimento e a composição química... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The thesis is organized in two chapters. The first chapter tested the hypothesis that the growth of Eichhornia crassipes, Pistia stratiotes and Salvinia molesta is related with the absorption of phosphate and nitrogen. It was studied the effect of different nutrient concentrations on the growth rate and orthophosphate (P-PO4) and total inorganic nitrogen (NIT) absorption rate in E. crassipes, P. stratiotes and S. molesta. The three species cultivated in low nutrient concentrations showed the highest absorption rate of P-PO4 and NIT between 0- 5 days. In high nutrient concentrations the highest absorption rate of P-PO4 for all species occurred between 0-5 days and the highest rate of absorption of NIT for P. stratiotes occurred between 5-10 days and for E. crassipes and S. molesta occurred between 10-15 days. The gain of mass of S. molesta in low concentration was 12.8 times minor than E. crassipes and 1.3 times minor then P. stratiotes and absorption rate in the same period were similar for the tree species. A similar pattern was observed in high concentration of nutrients. However, S. molesta have lower efficiency to absorb nutrients and have lower stock of N and P, due to the minor gain of biomass. E. crassipes and P. stratiotes showed vertical growth that provided high gain of biomass and consequently high uptake of nutrients and stock of N and P in the biomass. We concluded that S. molesta have lower efficiency in wetlands to treat effluents. In the chapter II we investigate the effect of different concentrations of phosphate in the water on the growth and the chemical composition of E. crassipes, P. stratiotes and S. molesta. The fully randomized experiment (4 treatment and 3 replicates) was conducted in the laboratory. The PPO4 concentration was different on the 4 treatment (< 0.005; 0.031; 0.31; 3.1 mg.L-1). The constant derivates from Michaelis Menten model that defined... (Complete abstract click electronic access below) / Orientador: Antonio Fernando Monteiro Camargo / Coorientador: Gustavo Henrique Gonzaga da Silva / Banca: Wagner Cotroni Valenti / Banca: Luiz Carlos Gazarini / Banca: Sidinei Magela Thomaz / Banca: Ciro Cesar Zanini Branco / Doutor
190

Estudo e identificação de nitrogênio em efluentes de curtume

Baur, Luciane January 2012 (has links)
A indústria curtumeira gera quantidades significativas de efluentes com altos níveis de nitrogênio. Este trabalho tem como objetivos avaliar os fatores que contribuem para os altos teores de nitrogênio nos efluentes de curtume, entre eles, os produtos químicos utilizados no processamento do couro, as etapas que mais influenciam nestes teores, a influência do tempo e quantificar o total de nitrogênio liberado em cada etapa por quilograma de pele processada. Os testes foram realizados em peles salgadas e testadas duas formulações distintas, coletando-se amostras dos banhos no final de cada etapa, a fim de avaliar as quantidades de nitrogênio individualmente nestes efluentes. Posteriormente, foram analisadas as etapas considerando a influência do tempo na liberação de nitrogênio processando-se separadamente pedaços de peles salgadas, com apenas uma das formulações e deixando cada etapa por, pelo menos, 24 horas com coletas de banho ao longo do processo. Os métodos utilizados para se determinar os teores de nitrogênio nos banhos residuais foram Nitrogênio Total Kjeldahl (NTK), Nitrogênio Amoniacal (N-NH3), Carbono Orgânico Total (TOC) e Proteína Solúvel. Informações técnicas dos produtos químicos indicam que alguns deles têm nitrogênio em suas composições. Com base nisso, fizeram-se ensaios de NTK nos produtos que poderiam conter nitrogênio. Os resultados detectaram nitrogênio nas amostras desses produtos analisados, porém não em quantidades muito significativas. A partir dos resultados dos experimentos de processamento das peles foram calculadas as quantidades de nitrogênio, carbono e proteínas totais solúveis geradas por quilograma de pele processada. Para este cálculo, foram utilizados os resultados obtidos de NTK, TOC e proteínas totais solúveis, os volumes de banhos de cada etapa e a massa inicial da pele que estava sendo processada. Os resultados de liberação de nitrogênio por quilograma de pele processada (5,07 g/kg pele processada da Formulação Ribeira/Curtimento 1 e 5,51 g/kg de pele processada para a Formulação Ribeira modifica/Curtimento/Recurtimento 2) mostraram que as duas formulações liberam, aproximadamente, a mesma quantidade de nitrogênio por quilograma de pele processada. Comparando-se os resultados de NTK e N-NH3, verificou-se que grande parte do nitrogênio liberado nos banhos é de origem orgânica, ou seja, proveniente das peles, mostrando que devem ser feitos estudos mais profundos a fim de se gerar menores quantidades destes nos efluentes. Tratamentos adequados devem ser adotados nas estações de tratamento de efluentes, prevendo nitrificação e desnitrificação, a fim de depurar os altos índices deste nutriente nos efluentes finais antes de serem lançados nos corpos receptores. / The tannery industry generates significant amounts of effluent with high nitrogen levels. This work aims to evaluate the factors that contribute for high nitrogen contents in the effluent of tannery, among them, the used chemical products in the processing of leather, the main stages that influence in these contents, the influence of the time and to quantify the total residual nitrogen in each stage of the process for kilogram of processed hide. The tests had been carried out whit salted hides and two formularizations distinct were tested, collecting samples of residual water by the end of each stage, in order to evaluate the individual amounts of nitrogen in these effluents. Subsequently, steps were analyzed considering the influence of time on the release of nitrogen processing separately pieces of salted hides, with the usual formulation and leaving each stage for at least 24 hours for collecting samples of the waste water throughout the process. The methods used to analyze the levels of residual nitrogen in wastewater were Total Kjeldahl Nitrogen (TKN), Ammonia Nitrogen (NH3-N), Total Organic Carbon (TOC) and Soluble Protein. Technical information of chemicals products indicate that some of them have nitrogen in their compositions. On this basis, there have been trials to determine TKN in the products that could contain nitrogen. The results detected nitrogen in the analyzed samples of these products, but not in significant levels. From the results of the experiments the amounts of nitrogen, carbon and total soluble protein produced per kilogram of processed hide were calculated. For this calculation, were used the results of TKN, TOC, and total soluble protein, the volumes of each step of baths and the initial mass of hide. The results of release of nitrogen per kilogram of hide (5.07 g/kg of processed hide with the Formulation Beamhouse/Tanning 1 and 5.51 g/kg of processed hide with the modified Formulation Beamhouse/Tanning/Retanning 2) showed that both release approximately the same amount of nitrogen. Comparing the results of NTK and NH3-N, it was found that most of the nitrogen is released to the wastewater has organic origin, in other words, from the hide, demonstrating that further study must be made in order to generate lower quantities in these effluents. Appropriate treatment should be adopted in effluent treatment plants, providing nitrification and denitrification, in order to debug the high levels of this nutrient in the final effluent before being discharged in receiving waters.

Page generated in 0.0447 seconds