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Search Results: 1 - 10 of 356829 matches for " N.G. Fleck "
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Aplica o do herbicida diclofop na cultura da soja para controle de papu , Brachiaria plantaginea (Linck) Hitch Application of the herbicide diclofop in soybean for control of Brachiaria plantaginea (Linck) Hitch
N.G. Fleck
Planta Daninha , 1979,
Abstract: Durante o ano agrícola de 1977/78 foi conduzida uma pesquisa a campo na regi o da Depress o Central do Rio Grande do Sul, com o objetivo de estabelecer a dose e a época de aplica o do herbicida diclofop que proporcionassem controle mais eficiente do Papua e que oferecessem maior seletividade à cultura. Os tratamentos constaram de combina es das doses de 720, 1080 e 1440 g/ha de diclofop, e aplica es em pré-plantio incorporadas a o solo (PPI), pré-emergência (PRE), pós-emergência quando as plantulas de papu se apresentavam com duas folhas (POS-2) e outra na ocasi o em que se encontravam no estádio de quatro folhas (POS-4), as quais foram comparadas às testemunhas com papu durante o ciclo da soja (TCP) e sem papu (TSP). Os efeitos dos tra tamentos foram estimados através de avalia es visuais de controle e pelo rendimento de gr os de soja. Todos os tratamentos com diclofop proporcionaram rendimentos estatisticamente equivalente s, os quais n o se diferenciaram do controle sem papu , embora tivessem apresentado rendimentos significativamente superiores ao daquele com papu . Resultados das avalia es visuais, interpretados conjuntamente, evidenciaram que todas as combina es de doses e épocas de aplica o do diclofop controlaram eficientemente o papu . As percentagens do controle alcan ado, em rela o às testemunhas , variaram de 68 a 99%, dependendo do tratamento e da época da avalia o. Contudo, as aplica es em POS-2 nas dosesde 1080 e 1440 g/ha e em POS-4 na dose de 1080 g/ha demonstraram maior eficiência em controlar papu do que aquelas em PPI e em PRE à 720 g/ha. Several herbicide mixtures were tested on cotton, (Gossypium hirsutum L.) in the main production areas of the State of Minas Gerais, Brasil. The cultivar "Minas Dona Beta", was used in the Metalúrgica region, whilst in Triangulo and Norte the cultivar employed was ."IAC-13-1", . In Triangulo litle regrowth occurred up to 30 days after application when the following mixtures were used: dinitramine + diuron, dinitroanilin + prometryne and pendimethalin + diuron. These treatments controlled 96.2%, 92.5% and 96.5% of the total weeds, respectively. When yields were compared, 1,962 Kg/ha were obtained in the best treatment (pendimethalin + diuron), against the control plots average of 1,130 Kg/ha. Tank mixtures of 2,00 Kg/ha of alachlor and 0.35 Kg/ha of metribuzin, or 3,00 Kg/ha of alachlor and 0,50 Kg/ha of metribuzin, and 1,00 Kg/ha of trifluralin and 0,50 Kg/ha of metribuzin were the most efficient in controlling grasses and dicotyledons. Effective weed control was recorded in Nor th of
Competi o de azevém (Lolium multiflorum L. ) com duas cultivares de trigo Ryegrass (Lolium multiflorum L. ) competition with two wheat cultivars
N.G. Fleck
Planta Daninha , 1980, DOI: 10.1590/s0100-83581980000200001
Abstract: Com os objetivos de avaliar a habilidade de duas cultivares de trigo em competir com azevém (Lolium multiflorum, L.) e de estimar os efeitos da concorrência de várias densidades desta espécie sobre a cultura, foi conduzido experimento a campo durante a esta o de crescimento de 1978, na Esta o Experimental Agron mica da UFRGS, em Guaíba, RS. Foram comparadas as cultivares de trigo 'E-7414' e 'PAT-7219', na popula o de 300 plantas por m', com azevém semeado nas densidades de 0, 2,5, 5,0, 10,0 e 20,0 kg/ha, as quais originaram popula es médias de 0, 130, 210, 470 e 750 plantas por m2 , respectivamente. A competi o entre as espécies foi mantida durante o ciclo da cultura. Para o rendimento de gr os da cultivar 'E-7414', a competi o exercida pelo azevém ocasionou decréscimos variáveis entre 18% e 56%, dependendo da infesta o; enquanto para a cultivar 'PAT-7219', as redu es no rendimento de gr os se situaram entre 4c é 22%, conforme a densidade do azevém. Enquanto para 'PAT-7219' n o foram significativas as redu es no rendimento de gr os, para `E-7414' os decréscimos verificados alcan aram significancia estatística. A análise do peso da matéria seca do azevém demonstrou que este aumentou proporcionalmente ao aumento de sua popula o, mas que aquela variável foi significativamente menor quando o azevém esteve competindo com 'PAT-7219' do que com `E-7414'. Em média, diminuiu em 31% a matéria seca do azevém produzida sob 'PAT-7219' em rela o à `E-7414'. A field experiment was conducted to evaluate the ability of two wheat cultivars to compete with ryegrass (Lolium multiflorum L.), and to estimate the competition effects of various densities of this species on the crop, at the Agronomy Experimental Station, in Guaiba, RS, during the 1978 wheat growing season. Two wheat cultivars ('E-7414' and 'PAT-7219') were grown in competition with ryegrass at the densities of 0, 130, 210, 470, and 750 plants per m'. The competition effects were maintained during the whole wheat cycle. Depending on the weed population, ryegrass competition caused significant decreases, varying from 18 to 56%, in seed yield of the wheat cultivar `E-7414'; whereas, for `PAT-7219' cultivar, although seed yield reductions varied from 4 to 22% , were not statistically significant. Ryegrass dry matter production increased proportionally to its population. However, ryegrass dry matter yield was significantly lower whe n this specie s competed with 'PAT-7219' wheat cultivar than with 'E-7414'. As an average for the established densities, ryegrass dry matter produced in competi tion with 'PAT
Dose econ?mica ótima de acifluorfen + bentazon para controle de pic?o-preto e guanxuma em soja
Rizzardi, M.A.;Fleck, N.G.;
Planta Daninha , 2004, DOI: 10.1590/S0100-83582004000100015
Abstract: herbicide rates are established to be applied under a range of environment and crop management conditions. sometimes, herbicide rates can be reduced and, yet, suppress weed interference in a crop. the aim of this study was to test rate reduction for the herbicide acifluorfen + bentazon to control beggarticks (bidens spp.) and arrowleaf sida (sidarhombifolia), at different weed development stages relative to soybean emergence time. a field experiment was carried out in passo fundo, rs, with treatments consisting of five application times and four doble rates (1,25; 1,5; 1,75 e 2,0 l ha-1), plus two checks, (without weed control and with weeds removed by hand, at the same times of herbicideapplication. considering all the situations tested, the level of arrowleaf sida control varied from 80 to 99%, whereas that of beggarticks varied from 78 to 99%. for the whole cycle evaluation of the target species, the best control was found to be application in the four-leaf plants. increasing acifluorfen + bentazona rate in the1.25 to 2.0 l ha-1 range results in a positive linear soybean yield return.. the most biologically efficient rate was the 2.0 l ha-1 labeled rate. the rates close to 75% of the labeled rate provided thebest economic return.
Nível de dano econ?mico como critério para controle de pic?o-preto em soja
Rizzardi, M.A.;Fleck, N.G.;Agostinetto, D.;
Planta Daninha , 2003, DOI: 10.1590/S0100-83582003000200013
Abstract: adoption of the threshold level (tl) concept for weed management evaluates weed populations to implement control measures only when infestations overcome the tl. the objective of this research was to define tl for mixed infestations of bidens pilosa and bidens subalternans in the soybean crop. field experiments were conducted in passo fundo and eldorado do sul, rs, brazil. treatments consisted of mixed densities of the beggartick species and soybean seeding at 3, 7, and 11 days after cover crop desiccation. tl variable values were obtained from 0.4 to 33 beggartick plants m-2. different responses were obtained for crop-weed interference relations between the two locations evaluated. delaying soybean seeding in relation to cover crop desiccation increases beggartick interference in this crop. increases in yield loss per weed unit, in crop yield potential, harvested product value and herbicide efficiency were found to decrease tl values, making control potentially more economic. on the other hand, higher weed control cost increases tl values. it was also verified that seeds produced by non-controlled weeds below tl could compromise adoption of control decision based on this criterion.
Competitividade de dois genótipos de milho (Zea mays) com plantas daninhas sob diferentes espa?amentos entre fileiras
Balbinot Jr., A.A.;Fleck, N.G.;
Planta Daninha , 2005, DOI: 10.1590/S0100-83582005000300004
Abstract: competition between crops and weeds is influenced by plant morphophysiological characteristics and plant spatial arrangement. a field experiment was carried out in canoinhas-sc to evaluate the effect of row width and two corn genotypes on crop ability to compete against weeds. the treatments were arranged in a completely randomized design, using a factorial scheme (2x4x2), with four replicates. two corn genotypes with distinct morphological characteristics were grown under four row widths (0.4; 0.6; 0.8; and 1.0 m), with and without weeds. weed shoot dry matter, corn traits, corn yield and grain yield components were determined. weed dry matter decreased with reduced row width in both genotypes, though more intensely in the hybrid genotype than in the variety. corn grain yield increased with row width reduction under both interference conditions for the hybrid 'as-1544', but only under weed presence for the 'cateto' variety when row width decreased.
Nível de dano econ?mico como critério para tomada de decis?o no controle de guanxuma em soja
Fleck, N.G.;Rizzardi, M.A.;Agostinetto, D.;
Planta Daninha , 2002, DOI: 10.1590/S0100-83582002000300013
Abstract: threshold level (tl) is a simple concept that integrates biological and economical factors, which it is intended to make profitable the results of a decision process for weed control. the objective of this study was to determine tl for arrowleaf sida (sida rhombifolia) infestations, calculated on the basis of a single year, that could justify economic application of control measure in soybeans. field experiments were carried out in passo fundo and eldorado do sul, rs - brazil. treatments consisted of arrowleaf sida densities and soybean seeding times in relation to vegetation cover desiccation (3, 7, and 11; and 20, 24, and 28 days after). tl values varied from 2 to 50 plants m-2, whereas optimum tl ranged from 1 to 6 plants m-2. it was observed different responses for crop-weed interference relations with regard to the different environments evaluated. delaying soybean seeding in relation to vegetation cover desiccation increases arrowleaf sida interference severity in soybeans. it was noted that seeds produced by non controlled weed plants, at low tl densities, make difficult the control decision process based on this criterion.
Efeitos de três herbicidas pós-emergentes aplicados em diferentes horas do dia sobre ervas daninhas e plantas de soja [Glycine max (L.) Merrill] Effects of three post-emergence herbicides applied at various day times on weeds and soybean plants [Glycine max (L.) Merrill]
D.L.P. Gazziero,N.G. Fleck
Planta Daninha , 1980, DOI: 10.1590/s0100-83581980000100004
Abstract: O presente trabalho foi realizado na Esta o Experimental Agron mica da UFRGS em 1978/79, com o objetivo de determinar a influência das condi es ambientais ocorrentes em cinco horários de aplica o sobre três herbicidas pós-emergentes pulverizados sobre três espécies daninhas e sobre a cultura da soja. No experimento foram utilizados os produtos químicos acifluorfen, bentazon e dinoseb e as espécies daninhas Bidens pilosa L., Euphorbia heterophylla L. (em dois estádios de desenvolvimento), e Sida rhombifolia L. (em um estádio), como plantas teste. A ocorrência de baixa temperatura contribuiu para a redu o do controle de Bidens pilosa L. com acifluorfen, enquanto condi es de elevada umidade relativa do ar, contribuíram para aumentar o grau de controle de Euphorbia heterophylla L., principalmente quando pulverizada com dinoseb. Por outro lado, quanto mais eficiente foi o produto químico sobre determinada espécie, menor foi a interferência que sofreu dos fatores ambientais nos resultados alcan ados no controle. This research was conducted at the Agronomic Experimental Station UFRGS, Guaíba, RS, Brazil, during 1978/79, in order to study the influence of environmental conditions during five day times of spraying on the performance of three post-emergence herbicides applied over three weed species and soybeans. In this fi eld expe riment the compounds used were acifluorfen, bentazon and dinoseb, and the weed species tested were Bidens pilosa L., Euphorbia heterophylla L., in two growth stages and Sida rhombifolia L., in one stage. The occurrence of low temperature contributed to decrease the degree of Bidens pilosa L. control with acifluorfen, while high air humidity increased the degree of Euphorbia heterophylla L. control, mainly when this species was sprayed with dinoseb. On the other hand higher the herbicide efficiency on a particular weed species, the lower was the influence of the environmental conditions on the results attained on control.
Controle químico de azevém (Lolium multiflorum L.) na cultura do trigo Chemical control of ryegrass (Lolium multiflorum L.) in wheat
N.G. Fleck,R.J. Paulitsch
Planta Daninha , 1978,
Abstract: Em trabalho experimental a campo realizado em 1977 na regi o da Depress o Central do Rio Grande do Sul, avaliaram-se tratamentos herbicidas destinados a controlar seletivamente azevém (Lolium multiflorium L.) e trigo (linhagem E-7414); bem como também se objetivou estabelecer os níveis de competi o recíproca entre ambas as gramíneas. Foram comparados no experimento os herbicidas cianazina, clorobromuron, clorotoluron, diclofop, diuron, metoxuron e terbutrina com os tratamentos testemunhas: trigo sem azevém, trigo com azevém e azevém sem trigo. Todos os herbicidas foram aplicados em pós-emergência, quando o trigo se apresentava no estádio de 3-4 folhas, e o azevém se encontrava no estádio e 1-3 folhas. Verificou-se que a infesta o de azevém quando n o foi controlada de nenhum modo, ocasionou uma redu o média de 52% no rendimento de gr os de trigo. Por outro lado, constatou-se que a popula o de trigo, ao exercer competi o sobre as plantas de azevém, causou uma diminui o da ordem de 42% em sua matéria seca. Observou-se que todos os herbicidas demonstraram fitotoxicidade, havendo causado desde danos leves até muito severos às plantas de trigo, dependendo do produto utilizado; e, que os rendimentos de gr os obtidos dos tratamentos herbicidas foram inferiores ao da testemunha livre de azevém. No entanto, todos os compostos químicos testados apresentaram significativa atividade de pós-emergência, demonstrando potencial de controle ao azevém. Tanto a obten o da matéria seca do azevém, como a avalia o visual do seu controle demonstraram ser métodos apropriados para medir o efeito herbicida. Dentre os herbicidas avaliados, o diclofop foi o tratamento que propiciou controle mais eficiente ao azevém, menor grau de fitotoxicidade e mais elevado rendimento de trigo; de um modo geral, seguiu-se-lhes nestas características o clorotoluron. Os herbicidas clorobromuron e metoxuron, embora demonstrassem relativa seletividade ao trigo, exerceram inadequada atividade de pós-emergência sobre o azevém. O tratamento diuron mostrou comportamento insuficiente tanto em rela o ao controle do azevém, quanto ao rendimento do trigo. Os herbicidas cianazina e terbutrina proporcionaram adequado controle do azevém; contudo, suas seletividades à cultura do trigo foram muito reduzidas, além de terem causado diminui o no poder germinativo das sementes de trigo colhidas das parcelas tratadas com estes herbicidas. A field experiment was conducted during 1977 in the Central Depression region of Rio Grande do Sul to evaluate herbicide treatments to selectively control ryegrass (Lolium
Efeitos dos herbicidas glyphosate e paraquat, aplicados ao solo, sobre a emergência de feij o e soja e de algumas espécies daninhas Effects of the herbicides glyphosate and paraquat, applied to the soil, on the emergence of dry beans and soybeans and some weed species
C.A. Dias,N.G. Fleck
Planta Daninha , 1982, DOI: 10.1590/s0100-83581982000100004
Abstract: Em trabalho conduzido a campo na Esta o Experimental Agron mica da UFRGS, Guaíba, RS em 1979/80, usaram-se os herbicidas glyphosate, paraquat e sua combina o, objetivando determinar os efe itos de doses e de épocas de aplica o destes herbicidas em plantulas de feij o e de soja e sobre nutrientes do solo. Pelos resultados obtidos para emergência e peso de maté ria seca da parte aé re a de soja , n o houve di feren as para os tratamentos testados. Também n o ocorreram diferen as significativas à popula o in ic ia l de feij o e sobre os elementos de solo analisados (Ca, Mg e K). Com rela o ao peso de matéria seca da parte aérea do feij o, verificou-se que houve intera o entre herbicida e doses usadas, tendo glyphosate isolado e glyphosate mais paraquat aplicados seqüencialmente nas doses máximas causado redu o significativa naquele parametro. Com rela o ao paraquat, n o foram detectadas diferen as significativas entre as doses testadas. A field xeperiment was conducted during the 1979/80 growing season at the Agronomic Experimental Station of the Federal University of Rio Grande do Sul, in Guaíba, RS, Brazil, in order to evaluate the efects of rates and times of appl ication of the herbicides glyphosate, paraqu at, and the ir combin at ion, on dry beans (Phaseolus vulgaris L.) and soybeans (Glvcine max (L.) Merrill), and on some soil nutrierts. The results indicated no significant differences among the soybeans treatments tested fo r plant population and shoot dry weight. Also no sta ti sti cal diffe re nces occurred fo r dry beans plant population and for soil nutrients analysed (Ca, Mg, and K). For dry beans shoot dry weight, there was an interaction of herbicides and rates, where glyphosate sprayed alone and glyphosate plus paraquat applied at the maxima ra te s te sted caused significant decreases on that variable. For paraquat utilized alone, no significant effects were detected among the rates applied.
Antagonismo na associa??o de glyphosate e triazinas
Vidal, R.A.;Machry, M.;Hernandes, G.C.;Fleck, N.G.;
Planta Daninha , 2003, DOI: 10.1590/S0100-83582003000200016
Abstract: the no-tillage system requires herbicide spraying before planting to eliminate the existing weeds in the area and residual herbicides to prevent new weed infestation during the crop cycle. farmers tend to spray both groups of herbicide simultaneously to reduce costs and application time. the objective of this work was to verify the compatibility of glyphosate and triazine as a tank mix. an experiment was conducted under field conditions during the 2001-2002 growing season, using sorghum as a model to evaluate the herbicide mixture compatibility. sorghum hibrid dekalb 865 was planted in november 2001 and the treatments were sprayed 60 days after planting, when the plants were 100 cm tall and at the boot stage. treatments consisted of glyphosate at 540, 720 and 900 g ha-1, sprayed alone or in mixture with simazine + atrazine (primatop sc) at 1750 + 1750 g ha-1. treatments also included an untreated control and the residual herbicides used alone. the results of plant control and chlorophyll content indicated a severe antagonism in the glyphosate and triazine combination. herbicide antagonism reduced with increment of glyphosate rate or at late assessment periods.
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