1,720,964 research outputs found
Impact of tetraploid ryegrass on diploid ryegrass herbicide resistant
No full textCompetition between the tetraploid with natural population of the diploid ryegrass may be a tool to reduce resistant plants in the cultivated rangeland. The objective of this work was to evaluate the opportunity and the impacts of the use of tetraploid ryegrass genotypes in substitution to the diploid, in the crop-livestock systems of Rio Grande do Sul. To meet the objectives of present work, were done four studies, aiming: 1) evaluate the fitness cost, phenological development, yield components, and competitive ability, between diploid and tetraploid ryegrasses; 2) quantify the effect of rates of post-emergence herbicides on selectivity, and application of herbicides in different phenological development under the control of tetraploid ryegrass; 3) determinate the seeds longevity of diploid and tetraploid ryegrasses buried in different depths and periods; 4) measure the crossing between diploid and tetraploid ryegrasses to evaluate the physiological quality and viability of the seeds from the crossing, percentage of survival and inheritance of glyphosate resistance, as well as the level of ploidy from progenies. The results showed that the tetraploid ryegrass have a longer cycle than the diploid, due to the longer tillering period. The tiller number, leaf area, root dry mass and the number of seeds were higher to the tetraploid ryegrass, that also had a higher competitive ability than the diploid. The herbicides bentazon, 2,4-D, saflufenacil and carfentrazone-ethyl were selective to the tetraploid ryegrass regardless of the rate used. Glyphosate, diuron + paraquat, clethodim and haloxyfop showed satisfactory control to tetraploid ryegrass. Glufosinate had unsatisfactory control in tillering and stretching stages, however was good when was sprayed in flowering stage. Diploid ryegrass seeds got primary dormancy, avoiding the germination immediately after buried, while tetraploid seeds showed no dormancy, remaining in the seed bank in a quiescent stage. Both
genotypes have potentially emergent seeds in the fourth month after burial, when the environmental conditions (temperature, radiation and moisture) are adequate for the ryegrass development. Whatever of the genotype tested and the period after burial, seeds buried at greater depth showed superior longevity in the soil seed bank. Progeny from the susceptible tetraploid♂ x glyphosate resistant diploid♀ crossing
exhibited germination problems, with only one triploid plant being detected from the 22 plants evaluated. However, the progeny from the crossing between glyphosate resistant diploid♂ x tetraploid susceptible♀, did not show germination problems, but 46% of the plants died quickly after the seedling stage, with triploid (10%) and pentaploid (25%) seedlings identified. No glyphosate resistant plants were detected
in susceptible tetraploid♀ x resistant diploid♂ progeny, however in susceptible tetraploid♂ x diploid resistant♀ progeny, was observed a reduction of 47% of glyphosate resistant plants compared to cross-fertilization progeny resistant to glyphosate.Sem bolsaA competição intergenotípica de azevém tetraploide com a população natural diploide pode ser ferramenta para reduzir a frequência de indivíduos resistentes numa área. O presente trabalho teve por objetivo avaliar a possibilidade e os impactos do uso de genótipos de azevém tetraploide em substituição ao diploide, nos sistemas lavoura-pecuária do Rio Grande do Sul. Para atender os objetivos do deste trabalho, foram realizados quatro estudos, visando: 1) avaliar o valor adaptativo, ciclo e componentes de produtividade entre genótipos de azevém diploide e tetraploide; 2) quantificar o efeito de doses de herbicidas pós-emergentes sobre a seletividade e herbicidas em diferentes estádios de aplicação sob o controle de azevém tetraploide; 3) determinar a longevidade de sementes dos genótipos de azevém diploide e tetraploide, expostas a diferentes profundidades e tempo de enterrio; 4) mensurar a possibilidade de cruzamento entre genótipos diploides e tetraploides de azevém, determinando a qualidade fisiológica e viabilidade das sementes oriundas dos cruzamentos, percentagem de sobrevivência e herança da
resistência ao glyphosate, bem como, o nível de ploidia das progênies. Os resultados demonstraram que, o azevém tetraploide apresenta ciclo mais longo que o diploide, devido principalmente ao maior período de afilhamento. O número de afilhos, área foliar, massa seca de raiz e número de sementes foram superiores para o azevém tetraploide e, este apresentou habilidade competitiva superior ao diploide. Os herbicidas bentazon, 2,4-D, saflufenacil e carfentrazone-ethyl foram seletivos ao azevém tetraploide independente da dose empregada. Glyphosate, diuron + paraquat, clethodim e haloxyfop apresentam controle satisfatório, de azevém tetraploide. Glufosinate apresentou controle insatisfatório nos estádios de afilhamento e alongamento, no entanto adequado quanto pulverizado no estádio de florescimento. Sementes de azevém diploide apresentaram dormência primária, impedindo a germinação imediata após deposição no solo, enquanto sementes tetraploides não demonstraram dormência, permanecendo no banco de sementes em estado quiescente. Ambos os genótipos apresentaram sementes potencialmente emergentes no quarto mês após o enterrio, quando as condições ambientais (temperatura, radiação e umidade) são adequadas para o desenvolvimento da espécie. Independente do genótipo testado e do tempo, quanto maior a
profundidade de enterrio das sementes, maior a longevidade no banco de sementes do solo. A progênie oriunda do cruzamento diploide resistente ao glyphosate♀ x tetraploide suscetível♂ apresentou problemas de germinação, sendo detectada apenas uma planta triploide das 22 avaliadas. Já, a progênie oriunda do cruzamento diploide resistente ao glyphosate♂ x tetraploide suscetível♀, não apresentou problemas de germinação, porém 46% das plantas morreram logo após a fase de plântula, sendo identificadas plântulas triploides (10%) e pentaploides (25%) nesse cruzamento. Não foram identificadas plantas resistentes ao glyphosate na progênie diploide resistente ao glyphosate♂ x tetraploide suscetível♀, já na progênie diploide resistente ao glyphosate♀ x tetraploide suscetível♂, apresentou redução de 47% de plantas resistentes ao glyphosate, em comparação a fecundação cruzada da progênie diploide resistente ao glyphosate
Impact of tetraploid ryegrass on diploid ryegrass herbicide resistant
No full textCompetition between the tetraploid with natural population of the diploid ryegrass may be a tool to reduce resistant plants in the cultivated rangeland. The objective of this work was to evaluate the opportunity and the impacts of the use of tetraploid ryegrass genotypes in substitution to the diploid, in the crop-livestock systems of Rio Grande do Sul. To meet the objectives of present work, were done four studies, aiming: 1) evaluate the fitness cost, phenological development, yield components, and competitive ability, between diploid and tetraploid ryegrasses; 2) quantify the effect of rates of post-emergence herbicides on selectivity, and application of herbicides in different phenological development under the control of tetraploid ryegrass; 3) determinate the seeds longevity of diploid and tetraploid ryegrasses buried in different depths and periods; 4) measure the crossing between diploid and tetraploid ryegrasses to evaluate the physiological quality and viability of the seeds from the crossing, percentage of survival and inheritance of glyphosate resistance, as well as the level of ploidy from progenies. The results showed that the tetraploid ryegrass have a longer cycle than the diploid, due to the longer tillering period. The tiller number, leaf area, root dry mass and the number of seeds were higher to the tetraploid ryegrass, that also had a higher competitive ability than the diploid. The herbicides bentazon, 2,4-D, saflufenacil and carfentrazone-ethyl were selective to the tetraploid ryegrass regardless of the rate used. Glyphosate, diuron + paraquat, clethodim and haloxyfop showed satisfactory control to tetraploid ryegrass. Glufosinate had unsatisfactory control in tillering and stretching stages, however was good when was sprayed in flowering stage. Diploid ryegrass seeds got primary dormancy, avoiding the germination immediately after buried, while tetraploid seeds showed no dormancy, remaining in the seed bank in a quiescent stage. Both
genotypes have potentially emergent seeds in the fourth month after burial, when the environmental conditions (temperature, radiation and moisture) are adequate for the ryegrass development. Whatever of the genotype tested and the period after burial, seeds buried at greater depth showed superior longevity in the soil seed bank. Progeny from the susceptible tetraploid♂ x glyphosate resistant diploid♀ crossing
exhibited germination problems, with only one triploid plant being detected from the 22 plants evaluated. However, the progeny from the crossing between glyphosate resistant diploid♂ x tetraploid susceptible♀, did not show germination problems, but 46% of the plants died quickly after the seedling stage, with triploid (10%) and pentaploid (25%) seedlings identified. No glyphosate resistant plants were detected
in susceptible tetraploid♀ x resistant diploid♂ progeny, however in susceptible tetraploid♂ x diploid resistant♀ progeny, was observed a reduction of 47% of glyphosate resistant plants compared to cross-fertilization progeny resistant to glyphosate.Sem bolsaA competição intergenotípica de azevém tetraploide com a população natural diploide pode ser ferramenta para reduzir a frequência de indivíduos resistentes numa área. O presente trabalho teve por objetivo avaliar a possibilidade e os impactos do uso de genótipos de azevém tetraploide em substituição ao diploide, nos sistemas lavoura-pecuária do Rio Grande do Sul. Para atender os objetivos do deste trabalho, foram realizados quatro estudos, visando: 1) avaliar o valor adaptativo, ciclo e componentes de produtividade entre genótipos de azevém diploide e tetraploide; 2) quantificar o efeito de doses de herbicidas pós-emergentes sobre a seletividade e herbicidas em diferentes estádios de aplicação sob o controle de azevém tetraploide; 3) determinar a longevidade de sementes dos genótipos de azevém diploide e tetraploide, expostas a diferentes profundidades e tempo de enterrio; 4) mensurar a possibilidade de cruzamento entre genótipos diploides e tetraploides de azevém, determinando a qualidade fisiológica e viabilidade das sementes oriundas dos cruzamentos, percentagem de sobrevivência e herança da
resistência ao glyphosate, bem como, o nível de ploidia das progênies. Os resultados demonstraram que, o azevém tetraploide apresenta ciclo mais longo que o diploide, devido principalmente ao maior período de afilhamento. O número de afilhos, área foliar, massa seca de raiz e número de sementes foram superiores para o azevém tetraploide e, este apresentou habilidade competitiva superior ao diploide. Os herbicidas bentazon, 2,4-D, saflufenacil e carfentrazone-ethyl foram seletivos ao azevém tetraploide independente da dose empregada. Glyphosate, diuron + paraquat, clethodim e haloxyfop apresentam controle satisfatório, de azevém tetraploide. Glufosinate apresentou controle insatisfatório nos estádios de afilhamento e alongamento, no entanto adequado quanto pulverizado no estádio de florescimento. Sementes de azevém diploide apresentaram dormência primária, impedindo a germinação imediata após deposição no solo, enquanto sementes tetraploides não demonstraram dormência, permanecendo no banco de sementes em estado quiescente. Ambos os genótipos apresentaram sementes potencialmente emergentes no quarto mês após o enterrio, quando as condições ambientais (temperatura, radiação e umidade) são adequadas para o desenvolvimento da espécie. Independente do genótipo testado e do tempo, quanto maior a
profundidade de enterrio das sementes, maior a longevidade no banco de sementes do solo. A progênie oriunda do cruzamento diploide resistente ao glyphosate♀ x tetraploide suscetível♂ apresentou problemas de germinação, sendo detectada apenas uma planta triploide das 22 avaliadas. Já, a progênie oriunda do cruzamento diploide resistente ao glyphosate♂ x tetraploide suscetível♀, não apresentou problemas de germinação, porém 46% das plantas morreram logo após a fase de plântula, sendo identificadas plântulas triploides (10%) e pentaploides (25%) nesse cruzamento. Não foram identificadas plantas resistentes ao glyphosate na progênie diploide resistente ao glyphosate♂ x tetraploide suscetível♀, já na progênie diploide resistente ao glyphosate♀ x tetraploide suscetível♂, apresentou redução de 47% de plantas resistentes ao glyphosate, em comparação a fecundação cruzada da progênie diploide resistente ao glyphosate
Identification and characterization of wild poinsettia biotypes with resistance to HPPD inhibitors
No full textWild poinsettia (Euphorbia heterophylla) is one of the main troublesome weed of
summer crops, due to the intrinsic aspects of competitiveness, combined with the
occurrence of resistant biotypes. Dose-response curve studies demonstrated
unsatisfactory control of some biotypes by hydroxyphenyl pyruvate dioxygenase
(HPPD) inhibitors, suggesting the occurrence of resistant biotypes. Thus, the
objectives of this work were to identify and characterize wild poinsettia resistance,
elucidate resistance mechanisms, verify changes in plant metabolism and characterize
the inheritance of resistance of Euphorbia heterophylla to HPPD-inhibiting herbicides.
To this end, a series of studies were carried out that were framed in four chapters, in
which they were carried out from March 2018 to April 2022, in a greenhouse and
laboratories at the Federal University of Pelotas. Initially, seeds collected in different
regions of Rio Grande do Sul state were evaluated for resistance to the herbicide
tembotrione, and control maps, dose-response curves, cross-resistance investigation
and alternative control were carried out (chapter 1). To elucidate the mechanisms of
resistance involved, studies of absorption, translocation, metabolism and identification
of known metabolites of tembotrione were evaluated, as well as the effect of inhibition
of P450 enzymes under exposure to the herbicide tembotrione and the quantification
of the expression of the HPPD gene (chapter two). To verify the changes in plant
metabolism between the biotypes, aspects related to photosynthesis, chlorophyll
fluorescence, pigments, cellular integrity and activity of antioxidant enzymes were
quantified (chapter 3). The mode and type of inheritance of resistance was determined
for the wild poinsettia biotypes resistant to the HPPD-inhibiting herbicides (chapter 4).
The results showed that biotype 32.2 presents multiple resistance to HPPD and PPO
inhibitors and biotype 32.1 presents multiple resistance to HPPD, PPO and ALS. The
pre-emergent atrazine, flumioxazin and sulfentrazone and the post-emergent atrazine,
paraquat, paraquat+diuron, saflufenacil, glyphosate, ammonium glufosinate
demonstrated satisfactory control of all wild poinsettia biotypes. Wild poinsettia
biotypes resistant to HPPD inhibitors present as a mechanism of resistance the rapid
metabolism of the herbicide tembotrione, to a non-toxic metabolite called TCMBA, and
no differential responses were observed between biotypes regarding absorption, P450
inhibition and HPPD gene expression. The increase in exposure of the susceptible
biotype to tembotrione results in a rapid increase in F0 and a marked reduction in Fm
and Fv/Fm, compared to resistant biotypes. Biotypes resistant to HPPD inhibitors show
a smaller decline in photosynthetic variables (A, Gs, E, CE and iWUE), in addition to a
smaller increase in Ci, in relation to the susceptible biotype, during the period of
exposure to the herbicide tembotrione. The increase in the period of exposure to the
herbicide tembotrione resulted in a significant increase in oxidative stress in the
susceptible biotype compared to the resistant ones, as evidenced by the increase in
TBARs, H2O2, cellular extravasation and lower carotenoid content. The higher activity
of APX 96 hours after application of tembotrione, in resistant biotypes resulted in lower
levels of H2O2 and less damage to cellular components. The inheritance of tembotrione
herbicide resistance is complex, being encoded by incompletely dominant nuclear
genes. Heterozygotes have intermediate sensitivity to the herbicide tembotrione,
where F1 R♂ x S♀ has a behavior closer to the susceptible parent, and F1 S♂ x R♀
is closer to the resistant parent.A leiteira (Euphorbia heterophylla) é uma das principais plantas daninhas de difícil
controle encontrado nas culturas de verão, devido aos aspectos intrínsecos de
competitividade da espécie, aliada à ocorrência de biótipos resistentes. Estudos de
curva dose-resposta demonstraram controle insatisfatório de alguns biótipos pela
aplicação de inibidores da hidroxifenil piruvato dioxigenase (HPPD), sugerindo a
ocorrência de biótipos resistentes. Desse modo, os objetivos deste trabalho foram
identificar e caracterizar a resistência de leiteira, elucidar os mecanismos resistência,
verificar as alterações do metabolismo vegetal e caracterizar a herança da resistência
de Euphorbia heterophylla aos herbicidas inibidores da HPPD. Para tal, foram
realizados uma série de estudos que foram enquadrados em quatro capítulos, nos
quais foram executados no período de março de 2018 a abril de 2022, em casa de
vegetação e laboratórios da Universidade Federal de Pelotas. Inicialmente, as
sementes coletadas em diferentes regiões do RS foram avaliadas quanto à resistência
ao herbicida tembotrione, sendo construídos mapas de controle, curvas de dose resposta, averiguação da resistência cruzada e controle alternativo (capitulo 1). Para
elucidar os mecanismos de resistência envolvidos, foram realizados estudos de
absorção, translocação, metabolismo e identificação dos metabólitos conhecidos de
tembotrione, bem como, o efeito da inibição das enzimas P450 sob exposição ao
herbicida tembotrione e a quantificação da expressão do gene HPPD (capítulo 2).
Para verificar as alterações no metabolismo vegetal entre os biótipos, foram
quantificados aspectos relacionados a fotossíntese, fluorescência da clorofila,
pigmentos, integridade celular e atividade de enzimas antioxidantes (capítulo 3). O
modo e tipo de herança da resistência foi determinada para os biótipos de leiteira
resistentes aos herbicidas inibidores da HPPD (capitulo 4). Os resultados
demonstraram que o biótipo 32.2 apresenta resistência múltipla aos inibidores da
HPPD e Protox e o biótipo 32.1 apresenta resistência múltipla a HPPD, Protox e ALS.
Os pré-emergentes atrazina, flumioxazina e sulfentrazone e os pós-emergentes
atrazina, paraquat, paraquat+diuron, saflufenacil, glifosato e amônio glufosinato
demonstraram controle satisfatório de todos os biótipos de leiteira. Os biótipos de
leiteira resistentes aos inibidores da HPPD apresentam como mecanismo de
resistência a rápida metabolização do herbicida tembotrione, para um metabolito
atóxico denominado de TCMBA, sendo que não foram observadas respostas
diferenciais entre os biótipos quanto a absorção, inibição das P450 e expressão do
gene HPPD. O incremento da exposição do biótipo suscetível ao tembotrione resulta
em rápido aumento da F0 e redução acentuada de Fm e Fv/Fm, em comparação aos
biótipos resistentes. Os biótipos resistentes aos inibidores da HPPD demonstram
menor declínio das variáveis fotossintéticas (A, Gs, E, CE e EUA), além de, menor
incremento da Ci, em relação ao biótipo suscetível, no decorrer do período de
exposição ao herbicida tembotrione. O incremento do período de exposição ao
herbicida tembotrione acarretou no aumento significativo de estresse oxidativo no
biótipo suscetível em comparação aos resistentes, evidenciado pelo aumento de
TBARs, H2O2, extravasamento celular e menor conteúdo de carotenoides. A maior
atividade da APX 96 horas após a aplicação de tembotrione, nos biótipos resistentes
acarretou menores níveis de H2O2 e menores danos aos componentes celulares. A
herança da resistência ao herbicida tembotrione é complexa, sendo codificada por
genes nucleares de dominância incompleta. Os heterozigotos possuem sensibilidade
intermediária ao herbicida tembotrione, onde a F1 R♂ x S♀ apresenta comportamento
mais próximo ao genitor suscetível, e a F1 S♂ x R♀ mais próxima ao genitor
resistente
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
