Soaking is an important unit operation during the processing of seeds used for direct consumption. The change in seed volume over time during soaking (volume kinetics) relates to water uptake and the quality of final product, and affects the design of the entire processing operation. Since volume determination is labor-intensive and time consuming, volume kinetics is usually not well monitored throughout seed hydration. The first chapter of this thesis is a review on the importance of soaking and volume kinetics monitoring during seed processing, the factors affecting hydration in seeds, current volume measurement methods and models used to determine and describe the change in volume over time in seeds during soaking. The second chapter describes the design, construction and evaluation of a bean volumetric auto tester (B-VAT) for volume kinetics determination of seeds during soaking. Evaluation tests suggested the system can generate reliable, reproducible, and detailed volume kinetics results for seeds soaking at different conditions with limited labor requirements. In the third chapter, the volume kinetics of 6 pinto, 5 navy and 3 black bean cultivars were tested during soaking at 25 ºC and 55 ºC. Significant differences were observed among varieties and cultivars at both temperatures (p<0.01). As temperature increased, the hydration efficiency were enhanced for all cultivars, but with various degree. In the fourth chapter, we tested the hypothesis that a thin hydrophobic layer on the seed coat was responsible of the extended initial lag phase observed during the soaking of pinto beans. Hexane pre-treatment before soaking were used for all cultivars and contact angle measurement were done to determine the surface hydrophobicity of the beans. Good correlations were found between surface hydrophobicity and hydration efficiency of beans. Hexane effectively reduced the hydrophobicity of bean surface and improved the hydration efficiency of pinto beans. The fifth chapter covers the overall conclusion of this study and states recommendations of future work regarding the improvement of the developed system and further exploration of the bean hydration process.

Blueberry though one of the most valuable berry plants is limited in its occurrence in Lithuania. One of the reason – is lack of local cultivars. Over 1993 – 2004 the largest blueberry germ plasm was established in Kaunas Botanical Garden at VDU. This collection has been used for breeding of new cultivars. Seedlings ‘No.11, ’‘No.16’ and ‘No.17’ were investigated in Kaunas Botanical Garden over 2002 – 2004. The investigation aimed at estimating of productivity, character of fruiting and biochemical composition of berries. The obtained result were compare with those of halth-highbush ‘Northcountry’. Fruiting of 4 – 6 year old bushes was estimated, mean earliness of fruiting, berry size, volume and average yield for 3 seedling numbers were determined. Seedlings numbers ‘No.11, ��‘No.16’ and ‘No.17’might be classified as early cultivars. The main port of the blueberry yield was obtained in the first picking, due to this mechanised picking might be applied. The plants produce tasty, good marketable appearance and biochemical composition. The best marketable appearance typical of ‘No. 17’, the biggest berries – ‘No. 11����. The most productive were ‘No. 16’ and ‘No. 17’, their mean productivity is two times higher than that of ‘Northcountry’.

Lauko eksperimentas atliktas 2010–2012 m. Akmenės rajone, Kruopių seniūnijoje, Kruopių km. ūkininko Valiaus Ąžuolo ūkyje. Eksperimento lauko dirvožemis yra tipingas pasotintasis rudžemis (Eutric Cambisol). Tyrimų objektas – žieminių rapsų (Brassica napus var. oleifera DC) linijinės ir hibridinių veislių, pasėtų, į supaprastintai ir tradiciniu būdu dirbtą dirvą, pasėliai. Darbo metodai: ligų ir kenkėjų paplitimas vertintas naudojantis moksliniu metodiniu leidiniu ,,Žemės ūkio augalų kenkėjai, ligos ir jų apskaita“ (2002). Darbo rezultatai. Žemės dirbimas turėjo esminės įtakos fomozės pažeistų augalų proc. linijinės veislės žieminių rapsų pasėliuose. Fomozės pažeistų augalų dalis ir ligos intensyvumas buvo didesni hibridinių veislių pasėliuose. Žemės dirbimas ir veislė neturėjo esminės įtakos juodosios dėmėtligės paplitimui pasėliuose. Mažiau juodosios dėmėtligės pažeistų ankštarų buvo linijinės veislės pasėliuose, tačiau hibridinių veislių pasėliuose šios ligos intensyvumas buvo mažesnis. Žieminių rapsų pasėliuose verticiliozei mažiau atsparūs buvo hibridinės veislės rapsai. Žemės dirbimas turėjo esminės įtakos žieminių rapsų sėklų derlingumui. Didžiausias tirtų veislių žieminių rapsų sėklų derlingumas gautas taikant supaprastintą žemės dirbimą. 2010–2012 m. nenustatyta statistiškai patikimų priklausomumų tarp juodosios dėmėtligės, fomozės bei verticiliozės paplitimo pasėliuose ir sėklų derliaus. Nustatytas silpnas statistiškai patikimas tiesinis priklausomumas tarp... [toliau žr. visą tekstą] / Field experiment was conducted on 2010–2012 in the farm of Valius Ąžuolas in Kruopiai village, Kruopiai municipality, Akmene district. Soil of the experimental field – Eutric Cambisol. Object of the work – Winter rape (Brassica napus var. oleifera DC) crops of conventional and hybrid cultivars sown in the soil under traditional and reduced soil tillage. Method of the work – spreading of pests and diseases was evaluated using scientifical-methodical publication ,,Žemės ūkio augalų kenkėjai, ligos ir jų apskaita“ (Pests, diseases and their accouting in agricultural crops) (2002). The results of the work. Soil tillage significantly influenced the number of plants damaged by Leptospaeria spp. in crop of conventional winter rape cultivar. The percentage of plants damaged by Leptospaeria spp. and disease intensity was higher in crops of hybrid cultivars. Soil tillage and cultivar had no significant influence on the spreading of Alternaria brassica in winter rape crops. Lower amount of siliques damaged by Alternaria brassica was established in crops of conventional cultivar, but the intensity of this disease was lower in crops of hybrid cultivars. Winter rape of hybrid cultivars was less resistent for Verticillium dahliae. Soil tillage significantly influenced seed yield of winter rape. The highest seed yield of winter rape was obtained under reduced soil tillage. No significant correlations were established between seed yield of winter rape and diseases spreading in crops... [to full text]

No description available.

In 1931, Mungomery stated "whitegrubs have been for years past, and still are, the worst insect problem confronting the sugar industry". This statement remains true to this day, with canegrubs costing the Australian sugar industry A$7.22 million in lost production and in use of insecticides. The development of a sugarcane cultivar with resistance to canegrub attack would be a valuable addition to the recently implemented canegrub management program. This thesis examined the possibility that natural inhibitors derived from canegrubs could be incorporated in sugarcane to reduce or prevent its destruction by canegrubs. The research described here demonstrated that canegrub haemolymph contains inhibitors with activity against commercially purified enzymes and serine proteases found in crude midgut extracts. A cDNA encoding a potential canegrub protease inhibitor (DA10 12) belonging to the Ascaris family was cloned, but it did not have activity against the major canegrub midgut proteases. This protein does, however, still have potential for modification into a serine protease inhibitor suitable for use as a novel insect resistance transgene. The possibility of using haemolymph derived inhibitors as novel antimetabolites in a canegrub management strategy based on transgenic plants was also explored. The findings suggest that proteins with properties similar to those of DA10 12 will require the presence of a signal peptide and/or codon optimisation for successful expression in sugarcane. The research outlined in this thesis is the first investigation of protease inhibitors in the haemolymph of scarab larvae, and is the first report of an Ascaris family inhibitor that does not inhibit a serine protease.

The aim of this thesis is the evaluation of grain yield formation and state of health of the line and hybrid wheat. For this target it was founded a one-year small-land experiment on the land of the Faculty of Agriculture of The University of South Bohemia in České Budějovice in September 2014. The experiment had 16 different variants in four repetitions, where the main factor was the different cultivar - Hybrid Hymack and line Tobak were sown at two different dates (early date 20th September, late date 29th October). In both of sowing dates, cultivars also differed in amount of seed quantity, where for Hymack it was 1,1 and 2,2 MKS/ha and for Tobak it was 3,5 and 4,2 MKS/ha. The last option was the stimulation by using the products from the company EGT and checking. During the vegetation, the number of plants per square meter, number of tillers and number of spikes were monitored and the state of health was evalueted. After the harvest were evalueted the grain yield, volume weight, HTZ and the number of grains per spike. The indicative measurement was made by the N - tester and a Sun Scan. The results achieved during the one-year small-land experiment show, that due to the influence of favorable year and high intensity of cultivation, a line cultivar Tobak achieved a higher yield (10,4 t/ha) compared to hybrid cultivar Hymack (10,4 t/ha) about 7 %. In the evaluated parameters the biggest difference was in HTZ, when Tobak had 47 grams and Hymack had 43,5 grams. This difference was the reason for higher yield of the line cultivar. Both of cultivars have achieved a better yield in the early sowing date and responded positively to the application of the growth stimulators. On the contrary, in the late date of sowing, cultivars reached a higher volume weight of the grain. During the growing season, the hybrid cultivar had better state of health and considerably higher tillering capability and the leaf area. The hybrid wheat's yield potential can be applied especially in unfavorable conditions such as drought or poor quality soil. At high intensity of cultivation supported by suitable climatic conditions, hybrid wheat hasn´t got an economic application in comparison with profitable line cultivars. The reason for this, is the high price of the seed and need for higher doses of nitrogen. The hybrid wheats are suitable for unfavorable growing regions with early sowing.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objectives of this study were to evaluate the genetic progress of oat (Avena sativa L.), wheat (Triticum aestivum L.), and sunflower (Helianthus annuus L.) in trials organized and performed by the yield trials network of oat, wheat, and sunflower in the state of Rio Grande do Sul (RS), to evaluate the genetic progress in trials performed with and without fungicide use in oat for grain yield and hectoliter weight; to study the genetic progress in trials performed in homogeneous growing regions of wheat for grain yield; and to study the genetic progress in sunflower for grain yield, oil content, and oil yield. For oat, 89 trials belonging to the yield trials network were used with trials divided into with and without fungicide use and the trials were performed in nine municipalities in the RS during the period of 2007 to 2014. For wheat, 137 cultivar trials belonging to the state wheat cultivars trials (EECT) were used, with trials divided into two homogeneous growing regions. Trials were performed in 23 municipalities in the RS during the period of 2002 to 2013. For sunflower, 58 cultivars trials belonging to the sunflower genotypes assessment trials network were used and the trials were performed in 19 municipalities in the RS during the period of 2005 to 2014. The methodology proposed by Vencovsky et al. (1988) was utilized for the study of genetic progress and the balance of genetic progress was determined by the method of generalized least squares. The annual genetic progress for oat grain yield was 1.02% with fungicide use and 4.02% without fungicide use during the period of eight years in RS. Regarding the hectoliter weight, the annual genetic progress was 0.08% for trials with fungicide use and 0.71% for trials without fungicide use. Performing network yield trials with and without fungicide use in the aerial part is feasible to evaluate the efficiency of oat breeding programs in the introduction of disease resistance genes in released cultivars. Annual genetic progress for wheat grain yield during the period of 12 years in the state of RS was 2.86%, oscillating between homogeneous growing regions. The difference of annual genetic progress in region 1 (1.82%) in relation to region 2 (4.38%) justifies the study of genetic progress by homogeneous growing regions. Annual genetic progress of sunflower during the period of ten years (2005-2014) for grain yield was 8.58%, for oil content was -0.38%, and for oil yield was 7.13%. The sunflower breeding programs in the state of Rio Grande do Sul were efficient for the traits grain yield and oil yield and presented no efficiency for oil content. / Os objetivos deste estudo foram: avaliar o progresso genético das culturas de aveia branca (Avena sativa L.), de trigo (Triticum aestivum L.) e de girassol (Helianthus annuus L.), em ensaios organizados pelas redes de ensaios de aveia branca, trigo e girassol no Estado do Rio Grande do Sul (RS); estudar o progresso genético em ensaios conduzidos com e sem o uso de fungicidas na cultura de aveia branca para a produtividade de grãos e peso hectolítrico; estudar o progresso genético em ensaios conduzidos em regiões homogêneas de cultivo de trigo para produtividade de grãos; estudar o progresso genético na cultura de girassol para produtividade de grãos, teor de óleo e produtividade de óleo. Para a cultura de aveia branca foram utilizados 89 ensaios pertencentes a rede de competição de cultivares, com ensaios divididos com e sem o uso de fungicida, ensaios conduzidos em nove municípios do RS durante o período de 2007 a 2014. Para a cultura de trigo foram utilizados 137 ensaios de cultivares pertencentes ao ensaio estadual de cultivares de trigo (EECT), com ensaios divididos em duas regiões homogêneas de cultivo, estes ensaios foram conduzidos em vinte e três municípios do RS, no período de 2002 a 2013. Para a cultura de girassol foram utilizados 58 ensaios de cultivares pertencentes à rede de ensaio de avaliação de genótipos de girassol, os ensaios foram conduzidos em 19 municípios do RS, no período de 2005 a 2014. Para o estudo do progresso genético foi utilizada a metodologia proposta por Vencovsky et al. (1988) e determinado o balanço do progresso genético pelo método dos quadrados mínimos generalizados. O progresso genético anual para a produtividade de grãos de aveia branca, no período de oito anos no RS foi de 1,02% com a utilização de fungicida, e de 4,02% sem a utilização de fungicida. Com relação ao peso hectolítrico, o progresso anual foi de 0,08% para ensaios com fungicida e 0,71% sem aplicação de fungicida. A condução da rede de ensaios, com e sem o uso de fungicida na parte aérea é viável para avaliar a eficiência dos programas de melhoramento, na introdução de genes de resistência a patógenos nas cultivares lançadas. O progresso genético anual para a produtividade de grãos de trigo, no período de 12 anos, no estado do Rio Grande do Sul foi de 2,86%, oscilando entre as regiões homogêneas de cultivo. A diferença de progresso genético anual da região 1 (1,82%) em relação a região 2 (4,38%), justifica o estudo do progresso genético por regiões homogêneas de cultivo. O progresso genético anual de girassol no período de 10 anos (2005-2014), para a produtividade de grãos foi de 8,58%, para teor de óleo foi de -0,38% e para produtividade de óleo foi de 7,13%. Os programas de melhoramento genético da cultura de girassol no estado do Rio Grande do Sul foram eficientes para as variáveis produtividade de grãos e produtividade de óleo e não apresentaram eficiência para o teor de óleo.

Submitted by Izabel Franco (izabel-franco@ufscar.br) on 2016-10-04T15:03:04Z No. of bitstreams: 1 DissODG.pdf: 1134069 bytes, checksum: 201d9c8d363647a5dae351bd0d541d13 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-20T18:23:16Z (GMT) No. of bitstreams: 1 DissODG.pdf: 1134069 bytes, checksum: 201d9c8d363647a5dae351bd0d541d13 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-20T18:23:22Z (GMT) No. of bitstreams: 1 DissODG.pdf: 1134069 bytes, checksum: 201d9c8d363647a5dae351bd0d541d13 (MD5) / Made available in DSpace on 2016-10-20T18:23:29Z (GMT). No. of bitstreams: 1 DissODG.pdf: 1134069 bytes, checksum: 201d9c8d363647a5dae351bd0d541d13 (MD5) Previous issue date: 2016-05-13 / Não recebi financiamento / Maize is one of the most cultivated cereal in the world for its wide range of use in food, feed and industrial use. The production of grain and maize silage in organic system is essencial for the production of organic meat, milk and eggs, because this cereal makes up most of the rations and roughages used in a animal feed The objective was to evaluate the agronomic performance and bromatological parameters of silage of five commercial varieties (AL Avaré, AL Bandeirante, Cativerde 02, AL Piratininga and UFVM 200 - Soberano) and two maize landraces (Santa Rita 1 and Santa Rita 2), in two locations with climatic conditions and different altitudes (Araras / SP, 665 m altitude and Muzambinho / MG, 1100 m altitude) in organic production system. The experiment was carried out in a randomized block design in a 2x7 factorial with four replications. For evaluating the agronomic performance, was measured stalk diameter, plants height, insertion height of the upper ear, leaf number above the upper ear, Falker index of total chlorophyll, leaf nitrogen content, number of rows per ear, number of grain by row and grains per ear, lodging, final stand, 1000 grain weight and productivity. For the evaluation of bromatological parameters of silages was evaluated the productivity of green (GM) and dry matter (DM) and percentage of total dry matter (TDM), acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein (CP), mineral matter (MM), ether extract (EE), total carbohydrates (CHOT), and non-fiber carbohydrates (NFC) in silage. By results obtained, it was concluded that the agronomic performance of corn grain and the production of green and dry matter silages were influenced by environmental conditions, especially temperature and solar radiation, with better results in Muzambinho. But the environmental conditions not affected the bromatological parameters of silages, which were suitable for all varieties, in both locations. Under the experimental conditions, the landraces showed agronomic performance and bromatological parameters of silage similar to that of commercial varieties in two locations evaluated, indicating that they can be used in commercial crops under organic management. / O milho está entre os cereais mais cultivados no mundo, em função da versatilidade de usos na alimentação humana, ração animal e industrial. A produção de milho grão e silagem em sistema orgânico é essencial para a produção de carnes, leites e ovos orgânicos, uma vez que esse cereal compõe a maior parte das rações e volumosos utilizados na alimentação animal. Objetivou-se avaliar o desempenho agronômico e os parâmetros bromatológicos da silagem de cinco variedades comerciais (AL Avaré, AL Bandeirante, Cativerde 02, AL Piratininga e UFVM 200 - Soberano) e duas variedades crioulas (Santa Rita 1 e Santa Rita 2) de milho, em duas localidades com condições climáticas e altitudes distintas (Araras/SP, altitude de 665 m e Muzambinho/MG, altitude de 1100 m), em sistema orgânico de produção. O experimento foi conduzido em blocos casualizados em esquema fatorial 2x7 com quatro repetições. Para a avaliação do desempenho agronômico, mensurou-se o diâmetro de colmo, altura de plantas, altura de inserção da espiga superior, número de folhas acima da espiga superior, índice Falker de clorofila total, teor de nitrogênio foliar, número de fileiras por espiga, de grãos por fileira e de grãos por espiga, acamamento de plantas, estande final, peso de 1000 grãos e produtividade de grãos. Para a avaliação dos parâmetros bromatológicos das silagens, avaliou-se a produtividade de matéria verde (MV) e seca (MS) e porcentagens de matéria seca total (MST), fibra em detergente ácido (FDA), fibra em detergente neutro (FDN), proteína bruta (PB), matéria mineral (MM), extrato etéreo (EE), carboidratos totais (CHOT) e carboidratos não fibrosos (CNF) na silagem. Pelos resultados obtidos, concluiu-se que o desempenho agronômico do milho grão e a produção de matéria verde e seca das silagens foram influenciados pelas condições ambientais, principalmente radiação solar e temperatura, com melhores resultados obtidos em Muzambinho. Porém, as condições ambientais não influenciaram os parâmetros bromatológicos das silagens, que se mostraram adequados, para todas as variedades, nos dois locais de condução. As variedades crioulas apresentaram desempenho agronômico e parâmetros bromatológicos das silagens semelhante ao das variedades comerciais nos dois locais avaliados, indicando que as mesmas podem ser utilizadas em plantios comerciais sob manejo orgânico.

Made available in DSpace on 2014-06-11T19:24:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-06Bitstream added on 2014-06-13T19:52:28Z : No. of bitstreams: 1 garcia_cc_dr_sjrp.pdf: 2113284 bytes, checksum: a4643600e0920a3ad6487f475437561a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Com o intuito de agregar valor a frutas nacionais desidratadas, os efeitos de pré-tratamentos sobre a secagem de mamão Formosa foram avaliados. Para tanto, foram utilizados previamente à secagem convectiva o branqueamento, a desidratação osmótica (DO) e a aplicação de coberturas comestíveis na superfície das frutas frescas e osmoticamente desidratadas. Com base em um planejamento fatorial, verificou-se que a DO das fatias de mamão frescas e branqueadas em solução de sacarose a 50% p/p adicionadas de 1% p/p de lactato de cálcio e 0,1 M de ácido lático por 120 min e 105 min, respectivamente, foram as condições que ocasionaram redução na atividade de água das amostras e pequenas variações em sua cor. A cinética de DO das frutas frescas e branqueadas mostrou que o branqueamento resultou em maiores coeficientes de difusão da água e dos solutos. Melhores ajustes para as difusividades das fatias de fruta foram verificados considerando-as como placas infinitas. Os resultados evidenciaram grande atividade de invertase no mamão, o qual se apresentou como uma fonte potencial para a extração da referida enzima. As isotermas de sorção de fatias frescas, branqueadas e desidratadas osmoticamente de mamão Formosa mostraram que mais energia foi necessária para a remoção da água das amostras osmoticamente tratadas e que a dessorção das frutas branqueadas exigiu menor quantidade de energia. O branqueamento danificou a estrutura celular dos mamões resultando em maiores coeficientes de difusão da água que as frutas frescas durante a secagem. A desidratação osmótica dos mamões e a cobertura aplicada na superfície das frutas também resultaram em maiores coeficientes de difusão da água em relação às amostras frescas. A cobertura exerceu efeito protetor... / Aiming to add value to national dehydrated fruits, the effects of pre-treatments on convective drying of papaya of Formosa cultivar were investigated. Blanching, osmotic dehydration (OD) and edible coating application at the surface of fresh and osmotically dehydrated fruits were evaluated. Based on a factorial design, it was verified that OD of fresh and blanched papayas sucrose solutions at 50% w/w added with 1% w/w of calcium lactate and 0,1 M of lactic acid for 120 and 105 min, respectively, were the conditions resulting in decreased water activity and small color changes. OD kinetics of fresh and blanched fruits showed that blanching resulted in higher water and solutes diffusion coefficients. The best adjustments for the fruit diffusivities were obtained considering them as infinite slabs. The results revealed the great invertase activity in papaya which presented as a potential source for the referred enzyme extraction. Sorption isotherms of fresh, blanched and osmo-treated papayas showed that more energy was necessary to remove water from osmotically dehydrated samples and the dessorption of blanched fruits needed lower quantity of energy. Blanching damaged the cellular structure of papaya resulting in higher moisture diffusivities than the fresh fruits during drying. Osmotic dehydration and the coating applied at the surface of the fruits also resulted in higher moisture diffusion coefficients in relation to the fresh samples. Coating presented a protective effect on carotenoids content of the samples when applied at fresh fruits surface. Retention of vitamin C of fresh coated fruits was higher than the non-coated fresh and blanched papayas. Osmotic treatment did not have a protective effect on nutritional compounds of papayas, resulting in dried fruits with reduced vitamin C content

Made available in DSpace on 2015-03-26T13:40:05Z (GMT). No. of bitstreams: 1 texto completo.pdf: 841636 bytes, checksum: e76fa6ba8697bd0a60aa4b219d3b0456 (MD5) Previous issue date: 2007-03-02 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of this work was to study the effects of nitrogen fertilization and growth retardants on wheat (Triticum aestivum L.) crop. The study was conducted at the Experimental Station Prof. Diogo Alves de Mello, Federal University of Viçosa, Viçosa-MG (20º45 ' S; 42º51 ' W; 650-m altitude), in 2005 and 2006. Three experiments were carried out in a randomized block design with four repetitions. In the first experiment, two wheat cultivars (BRS 210 and Pioneiro) were fertilized by two methods of N application (total dose applied at seed sowing or 20 kg ha-1 at sowing and the remaining as topdressing in the beginning of tillering), and five N doses (40, 60, 80, 100, 120 kg ha-1) in a 2X2X5 factorial design. The results showed that the cultivar Pioneiro had higher productive potential than cultivar BRS 210, however with lower lodging resistance; splitting nitrogen fertilization increased lodging and brought no benefit to grain yield; grain yield response to N doses was quadratic, reaching maximum at 96.8 kg ha-1, and produced linear increase in lodging of cultivar Pioneiro. The second experiment, with the cultivar Pioneiro, had factors arranged in factorial and hierarchical design with a control treatment. The treatments consisted of three growth retardants (chlormequat, trinexapac-ethyl and paclobutrazol) combined in three doses (500, 1000 and 1500 g ha-1 of chlormequat; 62.5, 125 and 187.5 g ha-1 of trinexapac-ethyl and 40, 80 and 120 g ha-1 of paclobutrazol) with two application times (Time 1 = growth stage 6 or Time 2 = growth stage 8 of Feeks and Large scale), and a control treatment lacking retardant application. There was no occurrence of lodging in any of the studied treatments. It was concluded that trinexapac-ethyl and chlormequat were efficient in reducing wheat plant height; paclobutrazol was not efficient in reducing plant height; chlormequat and paclobutrazol effect on plant height was independent of application time; trinexapac-ethyl applied at growth stage 8 produced more marked effects than when applied at the stage 6 of the referred scale; the increase in retardant doses produced lower plant heights; chlormequat doses and paclobutrazol had no effect on grain yield; the largest trinexapac-ethyl doses reduced yield. The third experiment was arranged in a 5X4 factorial design, consisting of a combination of five nitrogen doses (30, 60, 90, 120, 150 kg ha-1) with four doses of the growth retardant trinexapac-ethyl (0, 62.5, 125, 187.5 g ha-1). Lodging and height of plants increased linearly with increase of nitrogen doses and with reduction of trinexapac-ethyl doses. Grain yield decreased with the increase of trinexapac-ethyl doses in the treatments with 30 and 60 kg ha-1 N, gave quadratic response in the treatments with 90 and 120 kg ha-1 N and had linear increase with 150 kg ha-1 N. Increasing N doses produced quadratic responses of grain yield with 0, 62.5, and 125g ha-1 of trinexapac-ethyl and linear increase with 187.5 g ha-. The results led to the conclusion that the application of 0, 62.5, 125 and 187.5 g ha-1 of 1 trinexapac-ethyl allows the use of 83.46; 92.21; 100.95 and 150 kg ha-1 of N, respectively, and that 60 kg ha-1 N without trinexapac-ethyl produces the highest grain yield. / O objetivo desta pesquisa foi estudar os efeitos da adubação nitrogenada e de redutores de crescimento na cultura do trigo (Triticum aestivum L.). O estudo foi conduzido na Estação Experimental Prof. Diogo Alves de Mello, da Universidade Federal de Viçosa, Viçosa-MG (20º45 S e 42º51 W e altitude de 650 metros), nos anos de 2005 e 2006. Foram realizados três experimentos, no delineamento de blocos casualizados com quatro repetições. No primeiro, duas cultivares de trigo (BRS 210 e Pioneiro) foram submetidas a duas formas de aplicação de N (dose total aplicada por ocasião da semeadura ou 20 kg ha-1 na semeadura mais o restante da dose em cobertura, no início do perfilhamento) e cinco doses de N (40, 60, 80, 100, 120 kg ha-1), constituindo um fatorial 2X2X5. Conclui-se que a cultivar Pioneiro apresenta maior potencial produtivo que a cultivar BRS 210, porém apresenta menor resistência ao acamamento; o parcelamento da adubação nitrogenada proporciona maior acamamento e não traz benefícios à produtividade dos grãos; as doses de N promovem resposta quadrática da produtividade dos grãos, com ponto de máxima estimado na dose de 96,8 kg ha-1 e, aumento linear do acamamento de plantas da cultivar Pioneiro. O segundo experimento, conduzido com a cultivar Pioneiro, foi montado com fatores em esquema fatorial e hierárquico com uma testemunha. Os tratamentos foram três redutores de crescimento (clormequat, trinexapac-etil e paclobutrazol) combinados com três doses (500, 1000 e 1500 g ha-1 de clormequat; 62,5, 125 e 187,5 g ha-1 de trinexapac-etil e 40, 80 e 120 g ha-1 de paclobutrazol) e duas épocas de aplicação (Época 1= estádio 6 ou Época 2= estádio 8 da escala Feeks e Large), mais um tratamento testemunha que não recebeu aplicação de redutor. Não houve acamamento de plantas em nenhum dos tratamentos estudados. Conclui-se que o trinexapac-etil e o clormequat são eficientes em reduzir a estatura das plantas de trigo; o paclobutrazol não é eficiente em reduzir a estatura das plantas; a ação dos redutores clormequat e paclobutrazol sobre a altura de plantas independe da época de aplicação; o trinexapac-etil aplicado na época em que as plantas encontram-se no estádio 8 promove efeitos mais acentuados, do que quando aplicado no estádio 6 da referida escala; o aumento das doses dos redutores promove menor estatura das plantas; as doses de clormequat e paclobutrazol não afetam a produtividade dos grãos; as maiores doses de trinexapac-etil promovem redução na produtividade. O terceiro experimento foi conduzido seguindo um fatorial 5X4, constituído pela combinação de cinco doses de nitrogênio (30, 60, 90, 120, 150 kg ha-1) com quatro doses do redutor de crescimento trinexapac-etil (0, 62,5, 125, 187,5 g ha-1). O acamamento e a altura das plantas aumentaram linearmente com o incremento das doses de nitrogênio e com redução das doses de trinexapac-etil. A produtividade dos grãos decresceu com o aumento das doses de trinexapac-etil, nos tratamentos com 30 e 60 kg ha-1 de N, respondeu de forma quadrática nos tratamentos com 90 e 120 kg ha-1 de N e aumentou de forma linear na dose de 150 kg ha-1 de N. O aumento das doses de N promoveu respostas quadráticas da produtividade dos grãos, nas doses de 0; 62,5, 125g ha-1 de trinexapac-til e aumento linear na dose de 187,5 g ha-1 do redutor. Conclui-se que a aplicação de 0; 62,5; 125 e 187,5 g ha-1 de trinexapac-etil permite utilizar as doses de 83,46; 92,21; 100,95 e 150 kg ha-1 de N, respectivamente, e que a dose de 60 kg ha-1 de N sem aplicação de trinexapac-etil promove a maior produtividade dos grãos.