CAPES / O tamanho de sementes utilizadas para a semeadura tem causado dúvidas entre os produtores de soja. O trabalho teve por objetivo verificar se poderiam haver diferenças entre tamanho de sementes com relação à profundidade de deposição do fertilizante. O experimento de campo foi realizado na Área Experimental da UTFPR Campus de Pato Branco, utilizando-se uma semeadora-adubadora de precisão para plantio direto. O delineamento utilizado foi o de blocos ao acaso, com cinco repetições. Os tratamentos foram compostos pela combinação entre dois tamanhos de sementes (semente grande com 6,5 mm e semente pequena com 5,5 mm) e duas profundidades de deposição do fertilizante em relação à semente (fertilizante próximo as sementes com aproximadamente 3 cm de distância e fertilizante distante das sementes com aproximadamente 10 cm). Os dados foram submetidos à análise de variância. Quando o valor do teste F foi significativo ao nível de 5% de probabilidade aplicou-se o teste de Duncan para a comparação de médias. A menor profundidade de deposição do fertilizante proporcionou maior número de vagens por planta e maior número de grãos por planta. Já a maior profundidade de deposição do fertilizante proporcionou maior altura de plantas aos 30 dias após a semeadura e na fase R2, maior área de solo mobilizada, maior população de plantas em todas as épocas avaliadas, maior profundidade de deposição de sementes e maior índice de velocidade de emergência. / The seed size used for seeding has caused doubts among soybean producers. The study aimed to determine whether there may be differences between seed size with respect to depth of fertilizer deposition. The field experiment was conducted at the Experimental Area UTFPR Campus Pato Branco, using a precision seeder for direct seeding. The design was a randomized blocks, with five repetitions. The treatments were composed by the combination of two seed sizes (large seed with 6,5 mm and 5,5 mm with small seed) and two fertilizer deposition depths in relation to the seed (fertilizer near the seed with about 3 cm away and fertilizer distant from the seeds with about 10 cm). Data were subjected to analysis of variance. When the test value F was significant at 5% probability was applied to the Duncan test for comparison of means. The shallower depth of fertilizer deposition provided larger number of pods per plant and increased number of grains per plant. Already the largest depth of fertilizer deposition provided greater plant height at 30 days after sowing and R2 stage, greater ground area mobilized, higher plant population in all periods, greater depth of deposition of seeds and a higher rate of emergency speed.

An experiment was conducted at Pongola (27°24´S, 31°25´E; 308m altitude) in South Africa to study the effects of season on growth and potential biomass and sucrose yields on nine commercial sugarcane cultivars. The treatments that were the focus in this study consisted of the cultivars NCo376, N25 and N26 ratooned in March, April, May, August and December. The crops were well fertilized and kept free of weeds and diseases. Irrigation applications were scheduled with a computer programme to keep the crops free of stress at all times. Shoot populations were counted regularly to study shoot density dynamics. Leaf appearance rates, sizes, numbers and senescence were measured to study the development of green leaf area. Green foliage, dead trash and stalk mass were measured at 4, 8, 10, 11 and 12 months in each of the starting times and also at 13 months in the March, April and May ratoon crops. The fibre, sucrose and non-sucrose content of stalks were determined on these harvesting occasions. Yields were calculated in terms of individual shoots and area (m‾²). The fraction of PAR intercepted by the developing canopies was measured until full canopy and daily intercepted solar radiation was interpolated for the entire crop. An automated meteorological station adjacent to the experiment site provided daily weather data. Shoot densities were described by thermal time, however, average peak shoot densities were lowest in the May ratoon (31.8 m‾²) and highest in the December ratoon (48.7 m‾²). Shoot senescence was most rapid in August and December ratoons. At the final harvest shoot densities were highest in the March, April and May ratoon (14.8 to 14.2 m‾²) crops. NCo376 (16.4 m‾²) and N25 (13.6 m‾²) had higher final shoot densities than N26 (10.5 m‾²). Leaf appearance rate was also well described by thermal time, however the first twelve leaves took longer to appear in crops started in December i.e. the first phyllochron was longer (109.5°C d) than in crops started at other times (80.4 to 94.5°C d). Leaves produced during the early stages of December and August ratoon crops were larger (e.g leaf number 13 of N26 was 443 to 378 cm²) than in other crops. April and May ratoon crops produced much smaller leaves (e.g leaf number 9 of N26 was 170 to 105 cm²). Leaf senescence was slower in April and May ratoon crops (0.36 to 0.46 leaves per 100°C d) than in March (0.51 to 0.59 leaves per 100°C d) or August and December ratoon crops (0.60 to 0.68 leaves per 100°C d). December ratoon crops produced very high green leaf area indexes (LAI) (>7.0) at the age of four months; all other crops had lower LAI (3.3 to 6.0) and most peaked later (8 to 11 months of age). The LAI of N25 peaked at the age of 8 months while NCo376 and N26 peaked when 10 to 11 months old. Seasonal fraction of solar radiation intercepted was high in the March ratoon crops (0.84) and declined to 0.63 in the May ratoon crops and was highest in the December ratoon crop (0.88). N26 intercepted lower fractions of PAR than NCo376 and N25, particularly in the May and August ratoon crops. Biomass accumulation, although initially slow, tended to be linear in the March, April and May ratoon crops in relation to intercepted radiation. In August and particularly in the December ratoons biomass accumulation was initially rapid, and RUEs were high (2.65 g MJ‾¹ at 114 days in the December ratoon crops). However, biomass accumulation slowed when these December ratoon crops experienced winter. Low growth rates after winter, as well as low shoot densities resulted in December ratoon crops having produced significantly lower above-ground biomass yields (4 886 g m‾² at the age of 12 months) than March, April and May ratoon crops (6 760 to 5 715 gm‾² at the age of 12 months). The December ratoon crops responded poorly to the better growing conditions in spring and second summer and accumulated little biomass after winter. N26 shoots grew rapidly during the first 6-8 months of the December ratoon crop and it yielded better than NCo376 and N25 at harvesting (biomass yields were 5.8 and 13.3% higher at the age of 12 months, respectively). April ratoons produced significantly higher biomass yields (6 760 g m‾²) than March, August and December ratoons. May ratoon crops produced the highest cane fresh mass yields (18 151 g m‾²) and April, May and August ratoons produced significantly higher sucrose yields than March and December ratoons. The highest sucrose yield was produced by the April ratoon crop of N26 (2 385 g m‾²). On average, across the five ratoon dates, NCo376, N25 and N26 produced similar sucrose yields (1 902 to 1 959 g m‾²). Foliage production was severely limited during winter while sucrose accumulation was less affected by the low temperatures, resulting in accumulation of sucrose in the top sections of the culm. Low temperatures slowed the development of canopies in March, April and May ratoon crops, but these crops were able to recover their growth rates and produced high biomass and sucrose yields at the age of 12 months. The December ratoons experienced low winter temperatures (<12°C) when they had already accumulated relatively high yields and became moribund during winter. They were unable to accumulate any significant amounts of biomass during final four months before the final harvest at the age of 12 months. NCo376, N25 and N26 all yielded poorly in the December ratoon crop. However, there are cultivars that appear to be less sensitive to the low winters and are able to yield relatively well when they are ratooned in December. Sucrose yields of March, April and May ratoons were increased substantially (10.6 to 22.7%) by harvesting at the age of 13 months rather than at the age of 12 months. The poor growth of December ratoon crops after winter is possibly due to the recently revealed feedback signaling by high sugar levels induced by low temperatures on photosynthesis. The incorporation of the effects of low temperature and the feedback signaling with the objective of better simulating yields of December ratoons is a proposed study at the South African Sugarcane Research Institute. Annual mean sucrose yields of NCo376, N25 and N26 crops were estimated to be 17% higher in March than in December ratoons. The suggested short term remedy therefore of the poor December yields is to shift milling seasons to include March and exclude December harvested crops in the northern irrigated regions. March crops grow vigorously during the months close to harvesting and therefore have lower levels of sucrose content which can be corrected with chemical ripeners. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

Despite the importance of taro (Colocasia esculenta L. Schott) as a food security crop, scientific research on it is scanty in South Africa. Production site, planting date and fertiliser regime affect crop performance and quality, particularly that of cultivars, because they tend to be adapted to specific localities. Storage temperature and packaging method on the other hand affect the shelf-life. To investigate performance and quality of three taro cultivars in response to planting date and fertilisation, a study was carried out at two sites in KwaZulu-Natal, South Africa (Ukulinga and Umbumbulu), during the 2007/2008 growing seasons. The effect of two storage temperatures (12oC and ambient temperature) and three packaging methods (polyethylene bags, mesh bags and open boxes) on cormel quality following storage was also investigated for three cultivars. Delayed planting negatively affected the number of cormels plant-1 and fresh cormel mass plant-1. Fertilisation and cultivar affected the number of cormels plant-1 and fresh cormel mass plant-1 only when planting was done in October and November at both sites. Fertilisation increased the number of cormels plant-1 for all cultivars except Dumbe-dumbe. Dumbe-dumbe had the lowest number of cormels plant-1 but the highest number of marketable cormels plant-1. Dumbe-dumbe showed the lowest fresh cormel mass plant-1 in October and the highest in November at Ukulinga. Fertisation increased fresh cormel mass plant-1 in October at Umbumbulu. Dry matter content was negatively affected by fertilisation at Ukulinga. The response of dry matter content, specific gravity, protein, minerals, reducing sugars and starch content was variable depending on cultivar. Delayed planting negatively affected starch content for Dumbe-dumbe and Pitshi at Ukulinga. Fertilisation decreased starch content of Pitshi, while delayed planting increased sugar content for Dumbe-dumbe and decreased it for Mgingqeni and Pitshi at Umbumbulu. Dumbe-dumbe had higher starch content and higher reducing sugars. Considering all growth and quality parameters, it is recommended that Dumbe-dumbe is the best taro cultivar for crisping and the best time to plant it is October with 160 kg N ha-1 of organic fertiliser and November with 320 kg N ha-1 at Ukulinga whereas at Umbumbulu the best time to plant Dumbe-dumbe is October with 320 kg N ha-1 of the fertiliser. Starch granules degradation, alpha-amylase activity and sprouting increased with storage time and storage temperature. Cormels of Mgingqeni stored in polyethylene bags showed highest alpha-amylase activity and sprouting. Reducing sugar content increased and starch content decreased with time in storage and decline in storage temperature. It is recommended that taro cormels be stored in mesh bags at 12oC. The chapters of this thesis represent different studies presented as different papers. Chapter 1 is a general introduction to explain the study background and hypothesis. Chapter 2 is a general review of literature. Chapter 3 is on growth, development and yield of taro in response to planting date and fertilisation. Chapter 4 is on the influence of planting date and organic fertiliser on crisping quality of taro cormels. Chapter 5 is on changes in the surface morphology of starch granules and alpha-amylase activity of taro during storage. Chapter 6 is on the effects of pre- and post-harvest practices on starch and reducing sugars of taro. The last chapter is a general discussion and conclusions. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

Bambara groundnut is a protein-rich legume, with food security potential in drought-prone regions. It has been grown for many centuries and has remained an important crop to most African subsistence farmers. However, despite its high nutritional status and yield advantages in poor soils, it remains one of the neglected crops by science. There have now been recent efforts to study underutilised crops, with the aim of promoting them as healthy alternatives for people facing resource and environmental challenges and to contribute to food security. In order to do this, there needs to be information that can be used to advise farmers on the agronomic aspects of producing the crop. The overall aim of the study was to evaluate the response of bambara groundnut landraces to drought under controlled environment and field conditions. Seeds were initially collected from subsistence farmers in Jozini, KwaZulu-Natal, and characterised into three seed lots distinguished by seed coat colour: red, white and brown. In the initial study (Chapter 2) seed quality of bambara groundnuts was evaluated. Seed lots were used for standard germination (SG) and cold test (CT). Seeds were germinated under two conditions, 25°C for 8 days (SG) and 4°C for 7 days followed by 8 days at 25°C (CT). Germination percentage, seedling size and mass were determined. Desiccation tolerance was evaluated by suspending 30 seeds of each seed lot over saturated salt solutions of NaCl, LiCl, KNO3 and H2O (control) for 0, 2, 4, 8, 24 and 48 hours. Five seeds were sampled at each interval and stored at -21°C for 7 days. Samples were ground and analysed for proline content. In addition, early establishment performance of bambara groundnut was evaluated under controlled environment conditions in seedling trays using two water regimes (Chapter 2). The experimental design had three factors: seed lot (colour), priming (NaCl, LiCl, KNO3, H2O and control) and water regimes [25% and 75% Field Capacity (F.C.)]. The experiment was replicated three times. Seedling emergence was determined daily for 21 days. Seedling height and leaf number were determined weekly for three weeks, thereafter, seedling leaf area, root and shoot mass (fresh and dry), root and shoot lengths and root to shoot ratio were also determined. Seedlings were later transplanted in 90 pots for a pot trial in order to evaluate growth responses of bambara groundnut to water stress; plant height, leaf number and yield components were determined (Chapter 3). Lastly, the use of planting date selection as a management strategy for managing the occurrence of water stress under field conditions was evaluated in field trials. The experimental design was a split-split-plot design with planting date as main factor (early, optimum and late), irrigation and rainfed as sub-main factor, and seed colour as sub-plots (brown, red and white) arranged in a randomised complete block design (RCBD), with three replications. There were three planting dates: 7 September (early planting), 24 November (optimum planting) and 19 January (late planting). Results from Chapter 2 showed that the brown seed lot had the highest germination across treatments, followed by red and white seeds, respectively. There were significant differences between seed lots (P < 0.05) and salt solutions (P < 0.05) with respect to proline content. Seed proline content increased from 0 to 8 hours and later declined; NaCl was associated with the highest proline accumulation. There were highly significant differences (P < 0.001) between seed colours, priming treatments and F.C., as well as their interaction, with respect to seedling emergence. White seeds had the highest emergence, followed by brown and red, respectively. Priming seeds improved their emergence compared to the control, with highest emergence being observed in seeds treated with LiCl. Priming also improved emergence under water stress; 25% F.C. had the highest emergence compared to 75% F.C. Results from Chapter 3 showed that, seeds primed with NaCl and KNO3 resulted in tallest plants with the highest number of leaves per plant. However, NaCl and KNO3 were also the most affected under water stress. Priming was shown to improve germination and early crop establishment of bambara groundnut landraces under water stress. However, yield per plant did not improve in response to either halo- or hydro-priming. Results from field trials showed that in terms of the measured plant growth parameters (plant height, leaf number and LAI), bambara groundnut landraces were sensitive water stress. Water stress decreased yield components, and hence yield. However, selection of planting dates was shown to be a useful management tool for managing water stress under water limited field conditions. Choice of planting date significantly affected both plant growth and yield. The optimum planting date resulted in the best crop growth for all measured plant growth parameters followed by late and early planting dates, respectively. Seed quality was shown to be associated with seed lot colour. Darker coloured (red and brown) seeds performed better than light (white) seeds with respect to germination. Priming was also shown to improve germination and early crop establishment of bambara groundnut landraces under water stress. However, yield per plant did not improve following priming. Growth of bambara groundnut landraces was shown to be sensitive to water stress. Water stress decreased yield components and hence yield under both controlled and field conditions. Choice of planting date significantly affected both plant growth and yield. The optimum planting date was shown to be the best performing planting date. The findings of this study suggest that bambara groundnut seed performance in terms of germination, stand establishment and productivity is associated with seed lot colour. Seed priming improves seed performance and enhances crop capacity to withstand water stress. If the optimum planting date for groundnuts (late spring to early summer) is missed, better crop performance and yield are obtained from late planting (late summer to early spring) compared with early planting (early spring). Bambara groundnut has a potential for production under water stress conditions in controlled and field environments. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

O sistema de semeadura direta é caracterizado pelo mínimo revolvimento do solo e manutenção de resíduos vegetais em cobertura. Contudo, o descaso com o manejo do solo, tem proporcionado, sistematicamente, o surgimento de camadas compactadas em áreas agrícolas conduzidas nesse sistema, as quais podem ocasionar a diminuição da produtividade das culturas. Desse modo, o objetivo deste trabalho foi avaliar os parâmetros de máquina, solo e planta em função do cultivo de plantas de cobertura e quatro profundidades de atuação da haste sulcadora de adubo, em Latossolo compactado conduzido em sistema de semeadura direta. O experimento foi realizado em duas safras agrícolas (2013/2014 e 2014/2015) na área experimental da UTFPR, em um Latossolo Vermelho distroférrico, com textura muito argilosa (76% de argila). O experimento foi conduzido em delineamento de blocos ao acaso, sendo os tratamentos dispostos no esquema de faixas com dois fatores e quatro repetições, totalizando 32 unidades experimentais. Os tratamentos principais foram compostos pela combinação de quatro profundidades de atuação da haste sulcadora de adubo (6,5; 9,5; 12,5 e 15 cm) no processo de semeadura do milho e os secundários pelo cultivo de duas plantas de cobertura de inverno (aveia preta e nabo forrageiro). Os dados obtidos foram submetidos à análise de variância para verificação dos efeitos dos fatores profundidades de atuação da haste, plantas de cobertura do solo e sua interação. Quando o teste F foi significativo a 5% de probabilidade, as médias foram comparadas pelo teste de Tukey para os fatores qualitativos (plantas de cobertura de inverno). Para os fatores quantitativos (profundidades de atuação da haste sulcadora) e interações foi aplicado o teste de regressão polinomial. O aprofundamento da haste sulcadora ampliou a força de tração e a potência requerida na barra no processo de semeadura, bem como diminui a velocidade média do conjunto mecanizado e a força de tração específica, e apesar de gerar maior mobilização do solo na linha de semeadura não demostrou ser uma prática de manejo eficiente para aumentar a produtividade do milho. A utilização de plantas de cobertura e profundidades de atuação da haste, entre si, não modificaram os parâmetros de resistência do solo à penetração, densidade e porosidade do solo, na entrelinha de cultivo. A população final de plantas, o índice de velocidade de emergência de plântulas e os componentes de produção do milho não variaram em função da profundidade de atuação da haste sulcadora. / The system of direct sowing is characterized by the minimum tillage of the soil and maintenance of vegetal residues in cover. However, neglect with soil management has systematically provided the emergence of compacted layers in agricultural areas conducted in this system, which may lead to a decrease in crop productivity. Thus, the objective of this work was to evaluate the machine, soil and plant parameters as a function of the cultivation of cover plants and four depths of the fertilizer routing rod, in a compacted Oxisol conducted in a no - tillage system. The experiment was carried out in two agricultural crops (2013/2014 and 2014/2015) in the experimental area of UTFPR, in a dystroferric Red Latosol, with a very clayey texture (76% clay). The experiment was conducted in a randomized complete block design, and the treatments were arranged in two - factor and four replicate bands, totaling 32 experimental units. The main treatments were composed by the combination of four depths of fertilizer routing (6.5, 9.5, 12.5 and 15 cm) in the corn sowing process and the secondary ones by the cultivation of two cover crops Winter (black oat and forage turnip). The obtained data were submitted to the analysis of variance to verify the effects of the factors depths of rod actuation, soil cover plants and their interaction. When the F test was significant at 5% probability, the means were compared by the Tukey test for the qualitative factors (winter cover plants). For the quantitative factors (furrow depths) and interactions, the polynomial regression test was applied. The deepening of the furrowing rod increased the traction force and the power required in the bar in the sowing process, as well as reducing the average velocity of the mechanized set and the specific traction force, and despite generating a greater mobilization of the soil in the sowing line. Has been shown to be an efficient management practice to increase maize productivity. The use of cover plants and stem depths, among themselves, did not modify soil resistance parameters to soil penetration, density and porosity, in the intercrop line. The final population of plants, seedling emergence speed index and maize production components did not vary according to the depth of action of the furrowing rod.

CAPES; Fundação Araucária / No cenário nacional, a cultura da soja ocupa posição de destaque quanto à área plantada e ao volume de produção, sendo cultivada em grande parte no sistema de plantio direto. Esse sistema, devido ao intenso tráfego de máquinas e implementos na sua superfície tem acarretado problemas de compactação do solo, que tem ocasionado a queda de rendimento das culturas. A fim de minimizar este efeito as semeadoras-adubadoras utilizam os sistemas de abertura de sulco do tipo disco duplo ou haste sulcadora. O uso da haste passou a ser corriqueira por permitir o rompimento da camada superficial compactada, porém necessita de uma maior demanda energética, podendo causar excesso de mobilização do solo nas áreas onde não se observam elevados níveis de compactação. Assim, este trabalho teve como objetivo avaliar os efeitos de mecanismos sulcadores e níveis de compactação do solo na demanda de tração solicitada por uma semeadora-adubadora, no desenvolvimento e produtividade da cultura da soja, cultivada em um Latossolo Vermelho de textura argilosa, no período de duas safras agrícolas. Foi utilizado o delineamento em blocos ao acaso com parcelas subdivididas, sendo as parcelas principais compostas por quatro níveis de compactação do solo (N0 – Plantio Direto sem compactação adicional; N1, N2 e N3 – Plantio Direto submetido à compactação adicional, por meio de duas, quatro e seis passadas com trator, respectivamente) correspondendo as densidades do solo de 1,16, 1,20, 1,22 e 1,26 g cm-3, e as subparcelas por dois mecanismos sulcadores (haste sulcadora e disco duplo), com quatro repetições. Para avaliar a força de tração média, máxima e específica solicitada pela semeadora foi utilizada uma célula de carga, com capacidade de 50 kN e sensibilidade de 2 mV V-1, acoplada entre o trator e a semeadora, cujos dados foram armazenados em um sistema de aquisição de dados modelo CR800 da Campbell Scientific. Foram avaliados ainda a resistência do solo à penetração, profundidade de semeadura, profundidade e largura de sulco, área de solo mobilizada, índice de velocidade de emergência, marcha de emergência, estande final de plantas, diâmetro de colmo, altura de plantas, número médio de grãos por vagem, massa de 1.000 grãos, número de vagens por planta e produtividade da cultura. Os dados foram submetidos à análise de variância, as médias dos sulcadores foram comparadas pelo teste de Tukey (p≤0,05), enquanto que para o fator compactação do solo, foi adotada a análise de regressão polinomial, sendo os modelos selecionados, pelo critério de maior R2 e a significância (p≤0,05) dos parâmetros da equação. Independente do ano agrícola estudado, a resistência à penetração aumentou como os níveis de compactação do solo até em torno de 0,20 m de profundidade, e a densidade do solo influenciou os parâmetros de qualidade de semeadura, porém, não afetou a produtividade da cultura. Na primeira safra, foi observado maior produtividade com o uso do sulcador tipo haste. Na segunda safra, a haste sulcadora exigiu maior demanda energética com o aumento de densidade do solo e situação inversa com o disco duplo. O travamento das linhas de semeadura, possibilitou melhor desempenho da haste sulcadora em quebrar a camada compactada. / On the national scene, soybean crop occupies a prominent position in cultivated area and volume production, being cultivated largely in the no tillage system. This system, due to the intense traffic of machines and implements on its surface has caused soil compaction problems, which has caused the yield loss of crops. In order to minimize this effect the seeder-drill uses the systems to opening the furrow by shank or the double disc type. The use of the shank has become commonplace for allowing the disruption of the compacted surface layer, however requires greater energy demand and may cause excessive tillage in areas where there is not observed high levels of compaction. Thus, this study aimed to evaluate the effects of furrowers mechanisms and levels of soil compacting on traction requirement by a seeder-drill and on the growing and productivity of soybean in an Oxisol texture clay, in a two growing seasons. The experimental design consisted of randomized blocks with split plots with the main plots composed of four levels of soil compaction (N0 – no tillage without additional compaction, N1, N2 and N3 – no tillage subjected to compaction through two, four and six passes with tractor, respectively) corresponding to densities of soil 1.16, 1.20, 1.22 and 1.26 g cm-3, and subplots by two furrowers mechanisms (shank and double disc) with four replicates. To evaluate the average, maximum and specific traction force requested by the seeder-drill, was used a load cell, with capacity of 50 kN and sensitivity of 2 mV V-1, coupled between the tractor and seeder-drill, whose data are stored in a datalogger system model CR800 of Campbell Scientific. In addition, were evaluated the bulk density, soil mechanical resistance to penetration, sowing depth, depth and groove width, soil area mobilized, emergence speed index, emergence operation, final plant stand, stem diameter, plant height, average number of seeds per pod, weight of 1,000 seeds, number of pods per plant and crop productivity. Data were subjected to analysis of variance, the mean of furrowers were compared by Tukey test (p≤0.05), while for the factor soil compaction, polynomial regression analysis was adopted, selected models by the criterion of greater R2 and significance (p≤0.05) of equation parameters. Regardless of the crop season, penetration resistance increase as soil compaction levels up to around 0.20 m deep, and bulk density influenced the sowing quality parameters, however, did not affect the crop yield. In the first season, there was a higher productivity with the use of the shank type. In the second crop season, the shank demanded greater energetic requirement with the increase of bulk density and opposite situation with the double disc. The locking of sowing lines allow better performance of the shank to break the compacted layer.

CAPES; CNPq / Uma das alternativas para minimizar as perdas de nitrogênio (N), além do uso de cultivares de trigo (Triticum aestivum L.) mais eficientes na utilização desse nutriente, e a identificação de manejos que intensifiquem o aproveitamento do N. Para as cultivares e condições climáticas do Brasil, existem poucos estudos que tenham quantificado como o arranjo espacial de plantas afeta a eficiência de uso do N. O objetivo deste estudo foi avaliar o efeito de diferentes arranjos espaciais (combinação entre densidades de semeadura e espaçamento entre linhas) no desempenho agronômico e aproveitamento do N mineral aplicado. O experimento foi conduzido em Pato Branco, nas safras agrícolas de 2014 e 2015, em delineamento em blocos ao acaso, em modelo fatorial, com três repetições. Dois cultivares de trigo (CD 150 e Ametista) foram submetidos a quatro densidades de semeadura (150, 300, 450 e 600 sementes m-2), duas doses de N (20 e 120 Kg ha-1) e dois espaçamentos entrelinhas (0,17 e 0,25 m). As maiores produtividades de grãos foram alcançadas no menor espaçamento entrelinhas e alta dose de N, para ambos os cultivares e anos avaliados. As densidades, para máxima eficiência técnica, de 400 sementes m-2 para a cultivar CD 150 e 425 sementes m-2 para a cultivar Ametista proporciona os maiores rendimento de grãos, ambas para o menor espaçamento. A eficiência de uso, de absorção e de utilização do N foram superiores nas condições com menor nível de N. Em ambos os espaçamentos utilizados, a eficiência de uso do N foi favorecida no menor espaçamento, bem como a eficiência de absorção do N. Os resultados permitem concluir que o teor de N proveniente da mineralização da matéria orgânica deve ser empregado como parâmetro para aplicação de N em cobertura. Com isso, evitar o uso excessivo do mesmo e otimizar tanto o rendimento de grãos quanto os parâmetros da eficiência de uso do N. / An alternative to minimize Nitrogen (N) losses, beyond use of more efficient wheat (Triticum aestivum L.) varieties on the use of this nutrient, is the identification of managements to intensify the use of N. For the varieties and climatic conditions of Brazil, there are few studies that have quantified how the spatial arrangement of plants affects the N-use efficiency. The objective of this study was to evaluate the effect of different spatial arrangements (combination between seeding rates and row spacing) on agronomic performance and utilization of the applied mineral nitrogen. The experiment was conducted in Pato Branco in the crops year 2014 and 2015, in a randomized block design, a factorial model, with three replications. Two wheat cultivars (CD 150 and Ametista) were submitted to four seeding densities (150, 300, 450 and 600 seeds m-2), two N doses (20 to 120 kg ha-1) and two row spacings (0.17 and 0.25 m). The highest grain yields were reached at the lowest line spacing and high nitrogen dose for cultivars and evaluated years. The densities, for maximum technical efficiency, of 400 seeds m-2 for the cultivar CD 150 and 425 seeds m-2 for the cultivar Ametista provides highest grain yield, for both cultivars and years evaluated. The N-use efficiency, N-uptake efficiency and N-utilization efficiency were higher in the conditions with lower level of N. In both spacings used, N-use efficiency was favored in the least spacing, as well as N-uptake efficiency. The results showed that the N content from the mineralization of organic matter should be used as a parameter for N application in the cover. Thus, avoiding excessive use of it and optimize both the grain yield as the N-use efficiency parameters.

CAPES; Fundação Araucária / No cenário nacional, a cultura da soja ocupa posição de destaque quanto à área plantada e ao volume de produção, sendo cultivada em grande parte no sistema de plantio direto. Esse sistema, devido ao intenso tráfego de máquinas e implementos na sua superfície tem acarretado problemas de compactação do solo, que tem ocasionado a queda de rendimento das culturas. A fim de minimizar este efeito as semeadoras-adubadoras utilizam os sistemas de abertura de sulco do tipo disco duplo ou haste sulcadora. O uso da haste passou a ser corriqueira por permitir o rompimento da camada superficial compactada, porém necessita de uma maior demanda energética, podendo causar excesso de mobilização do solo nas áreas onde não se observam elevados níveis de compactação. Assim, este trabalho teve como objetivo avaliar os efeitos de mecanismos sulcadores e níveis de compactação do solo na demanda de tração solicitada por uma semeadora-adubadora, no desenvolvimento e produtividade da cultura da soja, cultivada em um Latossolo Vermelho de textura argilosa, no período de duas safras agrícolas. Foi utilizado o delineamento em blocos ao acaso com parcelas subdivididas, sendo as parcelas principais compostas por quatro níveis de compactação do solo (N0 – Plantio Direto sem compactação adicional; N1, N2 e N3 – Plantio Direto submetido à compactação adicional, por meio de duas, quatro e seis passadas com trator, respectivamente) correspondendo as densidades do solo de 1,16, 1,20, 1,22 e 1,26 g cm-3, e as subparcelas por dois mecanismos sulcadores (haste sulcadora e disco duplo), com quatro repetições. Para avaliar a força de tração média, máxima e específica solicitada pela semeadora foi utilizada uma célula de carga, com capacidade de 50 kN e sensibilidade de 2 mV V-1, acoplada entre o trator e a semeadora, cujos dados foram armazenados em um sistema de aquisição de dados modelo CR800 da Campbell Scientific. Foram avaliados ainda a resistência do solo à penetração, profundidade de semeadura, profundidade e largura de sulco, área de solo mobilizada, índice de velocidade de emergência, marcha de emergência, estande final de plantas, diâmetro de colmo, altura de plantas, número médio de grãos por vagem, massa de 1.000 grãos, número de vagens por planta e produtividade da cultura. Os dados foram submetidos à análise de variância, as médias dos sulcadores foram comparadas pelo teste de Tukey (p≤0,05), enquanto que para o fator compactação do solo, foi adotada a análise de regressão polinomial, sendo os modelos selecionados, pelo critério de maior R2 e a significância (p≤0,05) dos parâmetros da equação. Independente do ano agrícola estudado, a resistência à penetração aumentou como os níveis de compactação do solo até em torno de 0,20 m de profundidade, e a densidade do solo influenciou os parâmetros de qualidade de semeadura, porém, não afetou a produtividade da cultura. Na primeira safra, foi observado maior produtividade com o uso do sulcador tipo haste. Na segunda safra, a haste sulcadora exigiu maior demanda energética com o aumento de densidade do solo e situação inversa com o disco duplo. O travamento das linhas de semeadura, possibilitou melhor desempenho da haste sulcadora em quebrar a camada compactada. / On the national scene, soybean crop occupies a prominent position in cultivated area and volume production, being cultivated largely in the no tillage system. This system, due to the intense traffic of machines and implements on its surface has caused soil compaction problems, which has caused the yield loss of crops. In order to minimize this effect the seeder-drill uses the systems to opening the furrow by shank or the double disc type. The use of the shank has become commonplace for allowing the disruption of the compacted surface layer, however requires greater energy demand and may cause excessive tillage in areas where there is not observed high levels of compaction. Thus, this study aimed to evaluate the effects of furrowers mechanisms and levels of soil compacting on traction requirement by a seeder-drill and on the growing and productivity of soybean in an Oxisol texture clay, in a two growing seasons. The experimental design consisted of randomized blocks with split plots with the main plots composed of four levels of soil compaction (N0 – no tillage without additional compaction, N1, N2 and N3 – no tillage subjected to compaction through two, four and six passes with tractor, respectively) corresponding to densities of soil 1.16, 1.20, 1.22 and 1.26 g cm-3, and subplots by two furrowers mechanisms (shank and double disc) with four replicates. To evaluate the average, maximum and specific traction force requested by the seeder-drill, was used a load cell, with capacity of 50 kN and sensitivity of 2 mV V-1, coupled between the tractor and seeder-drill, whose data are stored in a datalogger system model CR800 of Campbell Scientific. In addition, were evaluated the bulk density, soil mechanical resistance to penetration, sowing depth, depth and groove width, soil area mobilized, emergence speed index, emergence operation, final plant stand, stem diameter, plant height, average number of seeds per pod, weight of 1,000 seeds, number of pods per plant and crop productivity. Data were subjected to analysis of variance, the mean of furrowers were compared by Tukey test (p≤0.05), while for the factor soil compaction, polynomial regression analysis was adopted, selected models by the criterion of greater R2 and significance (p≤0.05) of equation parameters. Regardless of the crop season, penetration resistance increase as soil compaction levels up to around 0.20 m deep, and bulk density influenced the sowing quality parameters, however, did not affect the crop yield. In the first season, there was a higher productivity with the use of the shank type. In the second crop season, the shank demanded greater energetic requirement with the increase of bulk density and opposite situation with the double disc. The locking of sowing lines allow better performance of the shank to break the compacted layer.

CAPES; CNPq / Uma das alternativas para minimizar as perdas de nitrogênio (N), além do uso de cultivares de trigo (Triticum aestivum L.) mais eficientes na utilização desse nutriente, e a identificação de manejos que intensifiquem o aproveitamento do N. Para as cultivares e condições climáticas do Brasil, existem poucos estudos que tenham quantificado como o arranjo espacial de plantas afeta a eficiência de uso do N. O objetivo deste estudo foi avaliar o efeito de diferentes arranjos espaciais (combinação entre densidades de semeadura e espaçamento entre linhas) no desempenho agronômico e aproveitamento do N mineral aplicado. O experimento foi conduzido em Pato Branco, nas safras agrícolas de 2014 e 2015, em delineamento em blocos ao acaso, em modelo fatorial, com três repetições. Dois cultivares de trigo (CD 150 e Ametista) foram submetidos a quatro densidades de semeadura (150, 300, 450 e 600 sementes m-2), duas doses de N (20 e 120 Kg ha-1) e dois espaçamentos entrelinhas (0,17 e 0,25 m). As maiores produtividades de grãos foram alcançadas no menor espaçamento entrelinhas e alta dose de N, para ambos os cultivares e anos avaliados. As densidades, para máxima eficiência técnica, de 400 sementes m-2 para a cultivar CD 150 e 425 sementes m-2 para a cultivar Ametista proporciona os maiores rendimento de grãos, ambas para o menor espaçamento. A eficiência de uso, de absorção e de utilização do N foram superiores nas condições com menor nível de N. Em ambos os espaçamentos utilizados, a eficiência de uso do N foi favorecida no menor espaçamento, bem como a eficiência de absorção do N. Os resultados permitem concluir que o teor de N proveniente da mineralização da matéria orgânica deve ser empregado como parâmetro para aplicação de N em cobertura. Com isso, evitar o uso excessivo do mesmo e otimizar tanto o rendimento de grãos quanto os parâmetros da eficiência de uso do N. / An alternative to minimize Nitrogen (N) losses, beyond use of more efficient wheat (Triticum aestivum L.) varieties on the use of this nutrient, is the identification of managements to intensify the use of N. For the varieties and climatic conditions of Brazil, there are few studies that have quantified how the spatial arrangement of plants affects the N-use efficiency. The objective of this study was to evaluate the effect of different spatial arrangements (combination between seeding rates and row spacing) on agronomic performance and utilization of the applied mineral nitrogen. The experiment was conducted in Pato Branco in the crops year 2014 and 2015, in a randomized block design, a factorial model, with three replications. Two wheat cultivars (CD 150 and Ametista) were submitted to four seeding densities (150, 300, 450 and 600 seeds m-2), two N doses (20 to 120 kg ha-1) and two row spacings (0.17 and 0.25 m). The highest grain yields were reached at the lowest line spacing and high nitrogen dose for cultivars and evaluated years. The densities, for maximum technical efficiency, of 400 seeds m-2 for the cultivar CD 150 and 425 seeds m-2 for the cultivar Ametista provides highest grain yield, for both cultivars and years evaluated. The N-use efficiency, N-uptake efficiency and N-utilization efficiency were higher in the conditions with lower level of N. In both spacings used, N-use efficiency was favored in the least spacing, as well as N-uptake efficiency. The results showed that the N content from the mineralization of organic matter should be used as a parameter for N application in the cover. Thus, avoiding excessive use of it and optimize both the grain yield as the N-use efficiency parameters.

MSc (Plant Production) / Department of Plant Production / See the attached abstract below