1,720,955 research outputs found
SELETIVIDADE DE HÃBRIDOS DE MILHO AO HERBICIDA GLUFOSINATO DE AMÔNIO
No full textA cultura do milho (Zea mays L.) desempenha papel fundamental nas diversas cadeias produtivas dentro do agronegócio, além de ser uma ferramenta importante na rotação de culturas. Entre os fatores que interferem significativamente no rendimento de grãos de milho as plantas daninhas merecem destaque, pois podem causar a redução de 80% no rendimento. É fundamental encontrar alternativas de controle em pós-emergência na cultura do milho, sobretudo com o aumento de plantas daninhas resistentes ao glifosato. Assim, o herbicida glufosinato de amônio pode ser uma alternativa de controle de plantas daninhas em pós-emergência no milho. Desta forma, o presente estudo tem por objetivo avaliar a resposta de hÃbridos de milho à diferentes doses de glufosinato de amônio aplicado em pós-emergência. O experimento foi conduzido na safra 2018/2019, em parcelas sub divididas, onde a parcela principal corresponde aos hÃbridos e as subparcelas as doses de glufosinato de amônio. O herbicida foi aplicado quando as plantas apresentavam de 4 a 6 folhas. As avaliações de fitotoxicidade foram realizadas aos 7, 14, 21 dias após a aplicação dos herbicidas, e o rendimento de grãos no final do ciclo da cultura. As avaliações de fitotoxicidade demonstram que os hÃbridos apresentam rápida recuperação da injúria causada pelo herbicida, pois aos 21 dias a maioria deles não apresentava mais sintomas visuais. A fitotoxicidade não afetou o rendimento de grãos. O glufosinato de amônio é um herbicida com potencial no controle de plantas daninhas em pós-emergência na cultura do milho
Interferência e limiar de dano econômico de caruru-roxo em soja
No full textThe objective of this work was to determine the interference and economic damage threshold of smooth pigweed (Amaranthus hybridus) in soybean. The experiments were carried out in two agricultural harvests (2020/2021 and 2021/2022) in an area with natural infestation of smooth pigweed. The treatments consisted of different levels of smooth pigweed infestation (0, 1, 3, 6, 9, and 12 plants per square meter) in an area cultivated with soybean. The design was completely randomized with ten replicates. The analyzed variables were: number of pods per plant; grains per pod; and soybean grain yield, converted into loss percentage in relation to the controls without the presence of smooth pigweed. One smooth pigweed plant per square meter can reduce soybean yield, on average, by 4.32 to 5.09%, whereas the presence of 12 plants per square meter reduces soybean yield by 36.03 to 37.93%. The economic damage threshold of smooth pigweed in soybean occurs in the range of 0.35 to 0.93 plants per square meter. When the cost of control is lower, the economic damage threshold is achieved with smaller infestations of 0.36 plants per square meter. However, when the cost of control is high, the economic damage threshold becomes economically viable with larger infestations above 0.63 plants per square meter.O objetivo deste trabalho foi determinar a interferência e o limiar de dano econômico de caruru-roxo (Amaranthus hybridus) em soja. Os experimentos foram realizados em duas safras agrícolas (2020/2021 e 2021/2022), em área com infestação natural de caruru-roxo. Os tratamentos consistiram de diferentes níveis de infestação de caruru-roxo (0, 1, 3, 6, 9 e 12 plantas por metro quadrado) em área cultivada com soja. O delineamento foi inteiramente casualizado com dez repetições. As variáveis analisadas foram: número de vagens por planta; grãos por vagem; e produtividade de grãos de soja, convertida em percentual de perda em relação aos controles sem a presença de caruru-roxo. Uma planta de caruru-roxo por metro quadrado pode reduzir a produtividade de grãos de soja, em média, de 4,32 a 5,09%, enquanto a presença de 12 plantas por metro quadrado reduz a produtividade de soja de 36,03 a 37,93%. O limiar de dano econômico de caruru-roxo em soja ocorre na faixa de 0,35 a 0,93 plantas por metro quadrado. Quando o custo de controle é mais baixo, o limiar de dano econômico é alcançado com infestações menores de 0,36 plantas por metro quadrado. No entanto, quando o custo de controle é mais alto, o limiar de dano econômico torna-se economicamente viável com infestações maiores, acima de 0,63 plantas por metro quadrado
Agronomic, physiological, and phytochemical responses of physalis to pre- and post-emergence herbicides
Full text linkCape gooseberry (Physalis peruviana L.) is a fruit crop with increasing economic and functional relevance, yet limited research exists on weed management practices for this species. This study aimed to evaluate the agronomic, physiological, and phytochemical responses of P. peruviana to various pre- and post-emergence herbicides under greenhouse and field conditions. Two biotypes were used to assess selectivity and crop tolerance to thirteen post-emergence and two pre-emergence herbicides. Post-emergence trials revealed that chlorimuron, fomesafen, and the mixture atrazine + simazine significantly reduced plant height and caused high phytotoxicity, especially under field conditions. Conversely, quizalofop, clethodim, fluazifop, and clodinafop (ACCase inhibitors) showed excellent selectivity and maintained yield levels comparable to the control. Pre-emergence applications of S-metolachlor exhibited minimal effects on plant growth and effectively reduced weed density, while imazaquin caused a dose-dependent reduction in plant height and yield, particularly in one biotype. Phenolic compound analysis indicated that both herbicide application and weed presence influenced fruit quality. Plants grown under weed-free conditions presented the highest total phenolic content, while high weed pressure or herbicide injury reduced phenolic accumulation, especially in biotype 2. The results demonstrate that while some herbicides pose risks to P. peruviana development, others offer promising weed control options with minimal impact on crop performance and fruit quality. These findings contribute to the development of safe and effective weed management strategies for this emerging crop
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
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