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Search Results: 1 - 10 of 69145 matches for " Walter Rodrigues da; "
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Efeitos da secagem intermitente sobre a qualidade de sementes de milho
Villela, Francisco Amaral;Silva, Walter Rodrigues da;
Anais da Escola Superior de Agricultura Luiz de Queiroz , 1991, DOI: 10.1590/S0071-12761991000100011
Abstract: the objective of this work was the evaluation of different air temperatures in intermittent drying on the quality of corn seeds, double hybrid ag-162, during the drying process. the study was carried out in three parts named 1, 2 and 3. each part was made up of three drying methods: natural drying, artificial-natural drying and artificial drying. in the artificial-natural drying and in the artificial drying, air temperatures of 70, 80 and 90°c were used, respectively, during the process named artificial (intermittent drying) . after the drying process, the seeds were stored during six months and evaluation was carried out four times every two months, by determination of moisture content, germination, accelerated aging and cold without soil. in the first and fourth periods, seed infestation, seed health and field emergence tests were put into effect. the analysis and the interpretation of the results, considering the drying process at temperature 70, 8 0 and 90°c and moisture content reducing from 16,5% to 13,0%, permited the following conclusions: a) the intermittent drying did not cause prejudicial effects on the physiological quality of corn seeds; b) the penicillium spp. incidence on corn seeds may be reduced by means of intermittent drying.
Danos mecanicos associados a patógenos e desempenho de sementes de milho
Cicero, Carlos Moure;Silva, Walter Rodrigues da;
Bragantia , 2003, DOI: 10.1590/S0006-87052003000200017
Abstract: the damages caused to seeds due to mechanized operations performed along the production process can negatively affect the quality of the material obtained. according to specific literature, this qualitative reduction can be aggravated when the injury interacts with the microorganisms found in the seed surface or in the soil at seeding. thus, by performing pathogen inoculations and injuries in the region of the endosperm cap, top of scutellum and black layer of corn seeds, the aim of this paper was to verify the existing relationship between the mechanical damages, the presence of microorganisms and seed performance. after sanitary and physiological tests were carried out it was concluded that the damages, particularly when aspergillus sp. and fusarium moniliforme were found in the seeds, promote progressive qualitative losses as they approach the embryo. when compared with one another the negative interferences of aspergillus sp. and f. moniliforme are more evident than those of the penicillium sp.
O uso da hidrata??o para estimar o desempenho de sementes de soja
Beckert, Osmar Paulo;Silva, Walter Rodrigues da;
Bragantia , 2002, DOI: 10.1590/S0006-87052002000100010
Abstract: studies have suggested that the hydration of seeds can be affected by the physiologic quality.in order to study the relationships among the variations on initial hydration, size and physiologic quality of soybean seeds this research was carried out at the seed analysis laboratory of the escola superior de agricultura luiz de queiroz-universidade de s?o paulo. three lots (cv.brs-157) with different physiologic quality had the seeds standardized according to thickness (5,16 mm) and submitted to hydration at 20 oc in variable periods (3, 6, 9 and 12h). after hydration, seeds were classified according to thickness the individual frequency in each fraction was estimated, followed by evaluations of physiologic quality. physiologic quality affected water content and the thickness reached by the soybean seeds during hydration; therefore, it is possible to compare the relative physiologic quality of lots by using the thickness frequency data in moisturized seeds.
Efeitos imediatos e latentes de tratamentos térmico e químico em sementes de Brachiaria brizantha cultivar Marandu
Martins, Leila;Silva, Walter Rodrigues da;
Bragantia , 2003, DOI: 10.1590/S0006-87052003000100011
Abstract: the objective of this research was to study the effects of thermal and chemical treatments on brachiaria brizantha cv. marandu seeds, particularly in relation to dormancy. seeds presenting dormancy indices higher than 25% and physical purity above 98% were submitted to temperatures of 65, 70, 75 and 80 °c for periods of 5, 10 and 15 hours and to immersion in sulphuric acid (98%, 36n) for 15 minutes. at the beginning and at the end of six months storage under uncontrolled laboratory conditions, seeds were evaluated in relation to germination, tetrazolium (viability), first count of germination, seedling shoot lenght, seedling emergence and speed of emergence index. some specific thermal treatments showed positive effects similar to sulphuric acid treatment in reducing seed dormancy without causing latent physiological deterioration; 70°c/15h was the best thermal treatment to dormancy reduction in cv. marandu.
A??es fisiológicas do calor e do ácido sulfúrico em sementes de Brachiaria brizantha cultivar marandu
Martins, Leila;Silva, Walter Rodrigues da;
Bragantia , 2006, DOI: 10.1590/S0006-87052006000300016
Abstract: aiming at to improve the methodology for application of heat to break dormancy seeds of brachiaria brizantha `marandu', the physiological performance of samples of ten seed lots of this forage, with dormancy indices superior to 25%, was studied after exposure to 70 oc for 5, 10, 15, 20, 25 and 30 hours and immersion in concentrated sulphuric acid for 15 minutes. at the beginning (immediate effect) and after six months (latent effect) storage under ambient uncontrolled conditions, the following evaluations were made: water content, germination, tetrazolium viability, sand emergence, speed of emergence index and shoot length. results indicated that exposure of seeds to 70 oc or to concentrated sulphuric acid reduce the dormancy rate and favor the physiological performance; after six months, the seeds submitted to 70 oc for 5 hours show performance superior to those of the other treatments.
Comportamento da dormência em sementes de braquiária submetidas a tratamentos térmicos e químicos
Martins, Leila;Silva, Walter Rodrigues da;
Pesquisa Agropecuária Brasileira , 2001, DOI: 10.1590/S0100-204X2001000700010
Abstract: the objective of this research was to study the effects of thermal and chemical treatments on brachiaria brizantha cv. marandu seeds, in relation to dormancy. seeds showing dormancy indices superior to 25%, and physical purity above 98%, were submitted to temperatures of 40, 55, 70 and 85°c for periods of 5, 10 and 15 hours, to immersion in sulphuric acid (98%, 36n) for 15 minutes, and to germination on substrate moistened with an aqueous solution of potassium nitrate 0,2%. at the beginning and at the end of storage for nine months under uncontrolled laboratory conditions, seeds were evaluated in relation to germination, tetrazolium viability, damages on lemma and palea, first count of germination, seedling shoot length, seedling emergence and speed of emergence index. thermal specific treatments reduce the dormancy index of seeds; heating at 70°c for 10 and 15 hours, besides reducing the dormancy index, also causes immediate positive effects on the performance of seeds without producing latent physiological deterioration. application of 85°c and immersion in sulphuric acid, although causing reduction in dormancy and immediate positive effects on performance of seeds, also promote latent physiological deterioration.
Comportamento fisiológico de sementes de tangerina (Citrus reticulata Blanco) submetidas à desidrata??o
Martins, Leila;Silva, Walter Rodrigues da;
Revista Brasileira de Fruticultura , 2006, DOI: 10.1590/S0100-29452006000100005
Abstract: the objective of this research was to study the immediate effects of dehydration on the physiological performance of 'cleopatra' tangerine (citrus reticulata blanco) seeds. seeds were hand extracted from mature fruits, washed in running water and then drained in the shade. following that, a representative portion of the seeds was removed so as to constitute the treatment containing the highest water content (49%) to be studied. the remaining seeds were submitted to dehydration in an equipment with forced air flow (28o±2oc) in order to obtain the treatments (39; 32; 24; 13; 10 and 7% h2o) relative to the other moisture contents desired. evaluations were made of the moisture level, the germination, the seedling emergence, and root, hypocotyl and seedling length. it was concluded that the physiological potential of the seeds, considering the interval of 49 to 7% moisture content, is favored by dehydration to 39% h2o.
Interpreta??o de dados obtidos em testes de vigor para a compara??o qualitativa entre lotes de sementes de milho
Martins, Leila;Silva, Walter Rodrigues da;
Revista Brasileira de Sementes , 2005, DOI: 10.1590/S0101-31222005000100003
Abstract: the objective of this research was to study, using corn seed lots, the possibility of establishing relations between vigor data obtained in the laboratory with those observed in the field. to do so, twenty eight corn seed lots (treatments) of the al bandeirante open-pollinated variety were standardized regarding seed moisture content, width, length and germination. afterwards, seed vigor tests were conducted in the laboratory (group a: modified cool germination test; accelerated aging; germination under variations in water availability; radicle, shoot and seedling length under variations in water availability) and in the field (group b: seedling emergence). in order to compare means the 5% tukey test was used; in addition, the seed lots were assigned points according to a ranking order of performance observed in each evaluation, following criteria of absolute and statistical classifications, so to group them in order of performance in the a and b test groups. interpretation of vigor data resulting from a group of tests acquires a complexity directly proportional to the number of tests and lots being compared. in this way, the use of absolute classification surpasses the statistical classification in the tasks of qualitatively ranking corn seed lots according to their general performance and, in addition, quantifies the relationship among the responses observed in the laboratory with those obtained in the field
Comportamento da dormência em sementes de braquiária submetidas a tratamentos térmicos e químicos
Martins Leila,Silva Walter Rodrigues da
Pesquisa Agropecuária Brasileira , 2001,
Abstract: O objetivo deste trabalho foi estudar os efeitos de tratamentos térmicos e químicos sobre a dormência em sementes de Brachiaria brizantha cv. Marandu. Sementes com taxas de dormência superiores a 25% e pureza física acima de 98% foram submetidas a temperaturas de 40, 55, 70 e 85°C durante 5, 10 e 15 horas, à imers o em H2SO4 (98%, 36N) por 15 minutos, e a substrato de germina o umedecido com KNO3 (0,2%). No início e ao final do armazenamento de nove meses, conduzido em ambiente n o-controlado de laboratório, as sementes foram avaliadas por meio dos testes de germina o, de viabilidade (tetrazólio), de danifica es nas glumelas (lema e pálea), de primeira contagem de germina o, de comprimento da parte aérea das plantulas, de emergência das plantulas e do índice de velocidade de emergência. Foi verificado que tratamentos térmicos específicos reduzem a taxa de dormência das sementes; aquecimentos a 70°C por 10 e 15 horas, além de reduzirem a taxa de dormência, apresentam efeitos imediatos positivos no desempenho das sementes, sem gerar deteriora o fisiológica latente. As aplica es de 85°C e de H2SO4, apesar de proporcionarem redu o na dormência e efeitos imediatos positivos no desempenho das sementes, promovem deteriora o fisiológica latente.
Efeitos imediatos e latentes de tratamentos térmico e químico em sementes de Brachiaria brizantha cultivar Marandu
Martins Leila,Silva Walter Rodrigues da
Bragantia , 2003,
Abstract: O objetivo da pesquisa foi o de estudar os efeitos, particularmente sobre a dormência, de tratamentos térmico e químico em sementes de Brachiaria brizantha cv. Marandu. Sementes, com taxas de dormência superiores a 25% e pureza física acima de 98%, foram submetidas às temperaturas de 65, 70, 75 e 80 degreesC durante 5, 10 e 15 horas e à imers o em H2SO4 (98%, 36N) por 15 minutos. No início e no fim do armazenamento de seis meses, realizado em ambiente n o controlado de laboratório, as sementes foram avaliadas por meio dos testes de germina o, de tetrazólio (viabilidade), de primeira contagem de germina o, de comprimento da parte aérea das plantulas, de emergência das plantulas e de índice de velocidade de emergência. Tratamentos térmicos específicos equiparam-se ao de H2SO4 ao reduzir a taxa de dormência das sementes sem provocar deteriora o fisiológica latente; a aplica o de 70degreesC por 15 horas destaca-se positivamente em rela o à de H2O4 e aos demais tratamentos térmicos.
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