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Search Results: 1 - 10 of 424339 matches for " Márcio Dias Pereira "
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Germination and development of jatropha seedlings under water stress conditions Germina o e desenvolvimento de plantulas de pinh o manso sob condi es de estresse hídrico simulado
Márcio Dias Pereira,José Carlos Lopes
Semina : Ciências Agrárias , 2011,
Abstract: The first step sequence that involves the germination process is imbibition. The limitation of water to the seed at planting time can reduce germination and velocty as well as the development of the seedling. Hence, the objective of this study was to evaluate the germination and seedling development of jatropha under conditions of water stress by polyethylene glycol (PEG6000). The study was conducted at the Research Laboratory of the Department of Crop Seeds, Federal University of Vi osa. We used seeds of jatropha in temperature de 30 °C under osmotic potential levels of 0.0, -0.2, -0.4, -0.6, -0.8, -1.0 and -1.2. The performance of seed germination and seedling development were evaluated by germination (first and second count), index of germination velocity, time of germination, length and primary root and hypocotyl length. The experimental design was completely randomized design with six levels of osmotic potential to more witnesses and four replications. We conducted the analysis of variance and regression of the data and curves fitted by quadratic polynomial model for all variables. The reduction in osmotic potential of the substrate caused a significant reduction in germination of seeds of jatropha, as well as the speed of germination and seedling performance of this species. The fall of germination and seedling performance is enhanced and levels considered critical to -0.2 MPa and inhibits germination from -1.2 MPa. A primeira etapa da seqüência que envolve o processo germinativo é a embebi o. A limita o de água para a semente no momento da semeadura pode diminuir a germina o e sua velocidade, bem como o desenvolvimento da plantula. Diante disto, o objetivo deste trabalho foi avaliar o desempenho germinativo e o desenvolvimento de plantulas de pinh o manso sob condi es de estresse hídrico simulado por polietilenoglicol (PEG6000). O trabalho foi desenvolvido no Laboratório de Pesquisa em Sementes do Departamento de Fitotecnia da Universidade Federal de Vi osa. Utilizaram-se sementes de pinh o manso em temperatura de 30oC sob os níveis de potencial osmótico de 0,0; -0,2; -0,4; -0,6; -0,8; -1,0 e -1,2. O desempenho germinativo das sementes e o desenvolvimento das plantulas foram avaliados pelos testes de germina o (primeira e segunda contagem), índice de velocidade de germina o, tempo médio de germina o, comprimento de raiz primária e comprimento do hipocótilo. O delineamento estatístico utilizado foi o inteiramente casualizado com seis níveis de potencial osmótico mais a testemunha com quatro repeti es. A redu o do potencial osmótico do sub
ACCELERATED AGING OF CUBIU (solanum sessiliflorum Dunal) SEEDS ENVELHECIMENTO ACELERADO EM SEMENTES DE CUBIU (solanum sessiliflorum Dunal)
Márcio Dias Pereira,Sebasti?o Martins Filho
Pesquisa Agropecuária Tropical , 2010, DOI: 10.5216/pat.v40i3.5608
Abstract: Cubiu is a native plant of the Amazon that has attracted attention due to its nutritional and pharmaceutical properties. The objective of this study was to adequate the methodology of accelerated aging test for vigor evaluation of solanum sessiliflorum seeds. Four seed lots of solanum sessiliflorum were tested for germination, first counting, plantule length, emergence and germination speed index. For accelerated aging, the temperatures 41oC, 42oC, and 45oC were tested for 24, 48, 72, and 96 hours. The accelerated aging test was efficient for vigor evaluation of solanum sessiliflorum seeds, with results similar to those found for first germination counting, plantule length, emergence and germination speed index, especially when conducted at 41oC, for 72 or 96 hours. KEY-WORDS: Solanum sessiliflorum Dunal; physiological quality; vigor; deterioration. O cubiu é uma planta nativa da Amaz nia, que tem despertado interesse pelas suas características nutricionais e farmacêuticas. O presente trabalho teve por objetivo adequar a metodologia do teste de envelhecimento acelerado, para a avalia o do vigor de sementes de cubiu. Para isto, sementes de quatro lotes foram submetidas a testes de germina o, primeira contagem, comprimento de plantula, emergência e índice de velocidade de germina o (IVG). Para o teste de envelhecimento acelerado, foram testadas as temperaturas de 41oC, 42oC e 45oC, durante os períodos de 24, 48, 72 e 96 horas. O teste de envelhecimento acelerado foi eficiente para avalia o do vigor das sementes de cubiu, fornecendo informa es semelhantes às obtidas na primeira contagem de germina o, comprimento de plantula, emergência e IVG, principalmente quando conduzido a 41oC, por 72 ou 96 horas. P
Matura??o fisiológica de sementes de quaresmeira
Lopes, José Carlos;Dias, Paulo César;Pereira, Márcio Dias;
Pesquisa Agropecuária Brasileira , 2005, DOI: 10.1590/S0100-204X2005000800012
Abstract: the objective of this work was to study the maturation process of tibouchina granulosa cogn. seeds. each inflorescence was identified in the day of its respective anthesis. samples of fruits and seeds were collected weekly, and diameter, weight, color, moisture content and dry matter were determined. after seed extraction, analyzes were made for coloring, moisture content, dry matter, 1,000 seeds mass, speed and percentage of germination. experimental design was carried out in a completely randomized block with four replications. analysis of data obtained led to the following conclusions: seeds physiological maturity occurred 84 to 105 days, and seed harvest should be done between 84 to 98 days after the anthesis. the parameters which best characterized seed physiological maturity and the time for harvesting were moisture content and dry matter weight. the largest germination percentage was verified in extracted seeds from 77 until 105 days after the anthesis, and seeds vigor increased until 91 days. the size and color of fruits and seeds demonstrated efficiency as maturation parameters. fruits initial dehiscences occurred after 105 days of the anthesis. tibouchina granulosa presented seed dormancy after maturation.
Cultivation of “Roxo de Valinhos” Fig Tree in Different Plant Densities for Production of Green Figs for Industry in the Region of Campo Das Vertentes-MG  [PDF]
Paulo Márcio Norberto, ?ngelo Albérico Alvarenga, José Clelio de Andrade, Filipe Almendagna Rodrigues, Lair Victor Pereira, Emerson Dias Gon?alves
Agricultural Sciences (AS) , 2018, DOI: 10.4236/as.2018.99076
Abstract: The objective of this work was to study the effect of different planting densities on the development and production of “Roxo de Valinhos” green figs for industry, in the Campo das Vertentes-MG region. The experiment was installed at the Risoleta Neves Experimental Field—CERN/EPAMIG. The plants used were three years old and were arranged in three randomized blocks, subject to three different planting densities, with spacings ranging from 1 m (4000 plants·ha-1), 1.5 m (2666 plants·ha-1), and 2 m (2000 plants·ha-1) between plants in the planting line and 2.5 m between row for all planting densities. The average length of the branches (m), average number of fruits per branch, average number of fruits per plant, average weight of fruits, average yield per plant and the average yield per hectare (kg) were evaluated. It was verified that, there were no significant differences in the length of branch and in the average weight of fruit, in the three densities of fig tree planting. (4000 plants·ha-1), the average number of fruits per branch (7.5), per plant (55.87) and yield per plant (878.93 kg) were lower, however. The average yield per hectare (3515.73 kg) was higher than in other growing densities. It is concluded that, the higher density of plants (4000 plants·ha-1), provides the highest productivity per area, without damages to the quality of the fruits.
Hydration of carrot seeds in relation to osmotic potential of solution and conditioning method
Pereira, Márcio Dias;Dias, Denise Cunha Fernandes dos Santos;Dias, Luiz Antonio dos Santos;Araújo, Eduardo Fontes;
Revista Brasileira de Sementes , 2007, DOI: 10.1590/S0101-31222007000300017
Abstract: the objective of this study was to monitor carrot seed hydration in water and osmotic solutions to define appropriate conditions for priming treatment. two brasília cultivar carrot seed lots were used. seeds were imbibed in -1.0 and -1.2 mpa peg 6000 osmotic solutions and in distilled water, in an incubator bod at 20oc, using two different hydration methods: imbibition in moistened paper towel sheets and in aerated solutions. the imbibition curves for each seed lot were drawn after determining seed moisture content at 2, 4, 6, 8, 10, 12, 24, 48, 72, 96 hours hydration in water and after 2, 4, 6, 8, 10, 12, 24, 48, 72, 96, 120, 144, 168, 192, 216, 264, 312 hours hydration in peg 6000 solutions. seed hydration in distilled water was faster than in peg 6000 solutions; the primary root protrusion occurred at 48 hours imbibition as seeds reached 54% moisture content. osmotic conditioning of carrot seeds should be performed by imbibition in peg 6000 -1.0 or -1.2 mpa solutions to attain 40% and 45% moisture content (moistened paper) or 40% and 45% (aerated solutions).
Germina??o e vigor de sementes de cenoura osmocondicionadas em papel umedecido e solu??o aerada
Pereira, Márcio Dias;Dias, Denise Cunha Fernandes dos Santos;Dias, Luiz Antonio dos Santos;Araújo, Eduardo Fontes;
Revista Brasileira de Sementes , 2008, DOI: 10.1590/S0101-31222008000200017
Abstract: the problems regarding carrot seeds performance in the field are constant justifying the use of techniques to accelerate germination and seedling emergence. the objective of this study was to evaluate the effects of two imbibition methods during priming on carrot seed germination and vigour.. two seed lots of carrot, brasília cultivar, were primed in peg 6000 -1.0 and -1.2mpa solutions for 4 and 8 days, at 20o c, using two imbibition methods: paper towel moistened with the respective solutions and immersion in aerated osmotic solutions. non-primed seeds were used as control. the seeds were submitted to the following tests: germination, first count, percentage and speed of seedling emergence in the field at 10 and 25 days after sowing and primary root length. priming in peg 6000 for four days was effective in increasing the percentage and speed of germination and seedling emergence in the field. for primary root length, priming in peg 6000 -1.2 mpa aerated solution was superior to moistened paper treatment.
Primed carrot seeds performance under water and temperature stress
Pereira, Márcio Dias;Dias, Denise Cunha Fernandes dos Santos;Dias, Luiz Ant?nio dos Santos;Araújo, Eduardo Fontes;
Scientia Agricola , 2009, DOI: 10.1590/S0103-90162009000200005
Abstract: uniformity and percentage of seedling emergence of direct-seeded vegetables have a major impact on their yield and quality. depending on temperature and soil water potential, carrot seeds performance in the field is poor justifying the use of techniques to accelerate the germination and seedling emergence. the objective of this work was to evaluate the effects of priming treatments, with and without aeration, on carrot seeds performance under water and temperature stress. two seed lots of carrots, brasília cultivar, were primed in peg 6000 -1.0 and -1.2 mpa solutions, for four and eight days, at 20oc, using two imbibition methods: priming in paper towel moistened with the respective solutions and immersion into aerated osmotic solutions. non-primed seeds were used as control. after priming, the seeds were dried at room temperature until reach initial seed moisture content. the seeds were submitted to the following tests: germination, first count, seedling emergence in the field, germination at sub-optimal (15oc) and supra-optimal temperature (30oc) and germination under water stress (peg 6000 at -0.4 mpa). priming in -1.0 and -1.2 mpa peg 6000 during four and eight days can be useful for improving carrot seedling emergence in the field and seed performance under supra and sub-optimal temperatures. aeration of the peg solution was beneficial when seeds were primed at -1.2 mpa for eight days.
Modelagem da estabilidade de tratores agrícolas de pneus
Khoury Junior, Joseph Kalil;Dias, Gutemberg Pereira;Cordeiro, Ricardo Reis;Souza, Cristiano Márcio Alves de;
Pesquisa Agropecuária Brasileira , 2004, DOI: 10.1590/S0100-204X2004000500008
Abstract: the knowledge of the stability limit of tractors is fundamental to the safety of the agricultural operations in order to avoid accidents. the objective of this research was to develop a mathematical model to predict the loss of tractor stability. the model was verified under dynamic conditions on a standardized track, with no implement attached to the tractor. in order to predict the loss of tractor stability, the mathematical model was implemented based on the tractor geometry and weight and on some information about the tractor placement on the track. forces and momentum analyses were accomplished to determine the equations that describe the static and dynamic tractor behavior on sloping terrain. it was used a 4x2 tractor. comparing the experimental to the model estimated tractor-overturning angle, it was concluded that the developed model is capable to predict the stability loss.
Envelhecimento acelerado de sementes de pinh?o-manso
Pereira, Márcio Dias;Martins Filho, Sebasti?o;Laviola, Bruno Galvêas;
Pesquisa Agropecuária Tropical , 2012, DOI: 10.1590/S1983-40632012000100017
Abstract: jatropha curcas l. is an oleaginous plant that has distinguished itself by presenting the qualities necessary to the biodiesel production. this study aimed to adjust the accelerated aging test methodology to evaluate the physiological potential of jatropha curcas seeds. for this, four seeds lots were initially characterized by water content, germination percentage and first counting, seedlings emergence percentage and speed index, low temperature germination, and shoot height. the treatments included three temperatures (41oc, 42oc, and 45oc) and four seeds exposure times (24, 48, 72, and 96 hours), in about 100% relative humidity. the accelerated aging test carried out for 24 hours, at 41oc, was efficient for evaluating the jatropha curcas vigour seeds, allowing to classify lots according to vigour levels, similarly to the germination first counting tests, seedlings emergence, low temperature germination, emergence speed index, and shoots height.
Effect of temperature and pre-germinative treatments in the germination of Adenanthera pavonina L. seeds / Efeito da temperatura e de tratamentos pré-germinativos na germina o de sementes de Adenanthera pavonina L.
Advanio Inácio Siqueira Silva,Viviana Borges Corte,Márcio Dias Pereira,Geraldo Rogério Faustini Cuzzuol
Semina : Ciências Agrárias , 2009,
Abstract: Adenanthera pavonina L. is a native tree specie from India and with extensive distribution in all Brazilian states, whose seeds have dormancy and present medicinal and economical interest. The objective of this research was to evaluate the effect of different temperatures and pre-germinative treatments on the germinative behavior of newly collected A. pavonina seeds. The seeds were submitted to three settled temperatures: 20, 25 and 30oC; and to five pre-germinative treatments: coating cutting with pliers, friction in sandpaper, immersion for twenty minutes in sulfuric acid, immersion in water at 80oC for 5 minutes and control (without any treatment). The vigor of the seeds was evaluated by the percentage, first count, speed and mean time of germination. The experimental design used was a completely randomized with four replications and the averages were compared by the Tukey test, at 5% probability. The best germinative performance of the seeds was at temperatures of 20 and 25°C and in the pre-germinative treatments of mechanical scarification through the coating cutting with pliers and friction in sandpaper, and chemical scarification with immersion for 20 minutes in sulfuric acid. Adenanthera pavonina L. é uma espécie arbórea nativa da índia e de ampla distribui o em todos os estados brasileiros, cujas sementes possuem dormência e apresentam interesse medicinal e econ mico. O objetivo desta pesquisa foi avaliar o efeito de diferentes temperaturas e tratamentos pré-germinativos sobre o comportamento germinativo das sementes de A. pavonina, recém colhidas. As sementes foram submetidas a três temperaturas fixas: 20, 25 e 30oC; e a cinco tratamentos pré-germinativos: desponte com alicate, atrito em lixa, imers o em ácido sulfúrico por vinte minutos, imers o em água a 80oC por 5 minutos e testemunha (sem tratamento). O vigor das sementes foi avaliado pela porcentagem, primeira contagem, velocidade e tempo médio de germina o. Utilizou-se o delineamento inteiramente casualizado, com quatro repeti es e as médias foram comparadas pelo teste de Tukey, a 5% de probabilidade. O melhor desempenho germinativo das sementes foi nas temperaturas de 20 e 25°C e nos tratamentos pré-germinativos de escarifica o mecanica através do desponte com alicate e atrito em lixa, e escarifica o química com imers o em ácido sulfúrico por 20 minutos.
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