1,720,980 research outputs found
Differential susceptibility of Conyza bonariensis biotypes to glyphosate and ALS-Inhibiting herbicides in Argentina
Full text linkThe aim of this study was to compare control of three stages biotypes (rosette, bolting, and repro- ductive stage) of Conyza bonariensis glyphosate susceptible biotype (S) and tolerant biotype (T) to glyphosate with glyphosate and mixtures of acetolactate synthase (ALS)-inhibiting. For glyphosate, the dose-response curves confirmed that injury of the biotype T relative to biotype S was signifi- cantly lower for both rosette and bolting stages. Resistance index (RI) for this herbicide was approximately 4 for both weed stages. At bolting, for both biotypes doses much higher than the recommended dose were required. For acetolactate synthase (ALS)-inhibiting herbicides, at the rosette stage, control of both biotypes was excellent with doses significantly lower than the recommended rate. All herbicides within this group showed a very low I50 relative to the recommended rate. These results indicate that biotypes difficult to control with glyphosate at the rosette and bolting stage may be controlled using acetolacte synthase (ALS)-inhibiting herbicides. Control for the reproductive stage was poor. A management program based on the combination of glyphosate with pre- and post-emergence acetolactate synthase (ALS) herbicides may be effective to control the weed.EEA ParanáFil: Puricelli, Eduardo Carlos Jose Maria. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Faccini, Delma Edith. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Metzler, Marcelo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná; ArgentinaFil: Torres, Patricia Susana. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; Argentin
Spurred Anoda (Anoda cristata) Competition in Narrow- and Wide-Row Soybean (Glycine max)
Full text linkThe effect of spurred anoda competition in narrow- (35 cm) and wide-row (70 cm) soybean was studied in field experiments for 2 yr. Vigorous early soybean growth in narrow- compared with wide-row soybean resulted in lower radiation transmitted through the canopy, which can partially account for greater competitiveness of narrow-row than wide-row soybean. Soybean plant height was not significantly influenced by the row spacing. Relative yield total (RYT), which is the relationship between yield in mixtures and in monocultures of the crop or the weed and indicates resource complementarity, was equal to 1 with 12 spurred anoda/m2 in the year with less precipitation. Regardless of the row spacing, spurred anoda gave resource use complementarity with the crop (RYT . 1) in all other treatments; therefore, partial avoidance of competition in mixed species was evident. Soybean aggressivity, which takes into account the effect of competition on both the crop and the weed and indicates competitive ability, decreased with weed density in both row spacings. Soybean yield loss at harvest was linearly related to relative dry weight 40 d after planting. Weed-free narrowand wide-row soybean produced similar yields. In the presence of the spurred anoda, soybean yield was greater in narrow-row compared with wide-row soybean only in the most humid year. A management system that uses quick canopy closure with narrow-row soybean can provide excellent soybean yield and suppression of low spurred anoda densities.Fil: Puricelli, Eduardo Carlos Jose Maria. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Faccini, Delma E.. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Orioli, Gustavo Adolfo. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Sabbatini, Mario Ricardo. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentin
Sensitivity of conyza sumatrensis biotypes to glyphosate and ALS-inhibiting herbicides at two growth stages
Full text linkConyza sumatrensis es una de las malezas más problemáticas de Argentina, con frecuentes fallas de control después de la aplicación de glifosato. El objetivo del trabajo fue evaluar la sensibilidad de biotipos de C. sumatrensis, en dos estados de desarrollo (roseta y vegetativo), a glifosato y a inhibidores de la enzima acetolactato sintasa (ALS). Se realizaron estudios de dosis-respuesta utilizando 0, 1/16, 1/8, 1/4, 1/2, 1, 2, 4, 8 y 16 veces la dosis recomendada para cada herbicida. Al estado de roseta el nivel de resistencia para glifosato fue de 9,8, mientras que en estado vegetativo ninguno de los biotipos fue controlado con la dosis recomendada, siendo menor la sensibilidad del biotipo R (IR = 2,3). El control de ambos biotipos con inhibidores de la ALS fue excelente al estado de roseta, con dosis menores que las recomendadas. Al estado vegetativo los controles fueron adecuados (80 %) con dosis menores que las recomendadas (0,16 X a 0,97 X), excepto para metsulfuron-metil + clorsulfuron en el biotipo S (1,75 X). Estos resultados confirmarían la existencia de un biotipo resistente a glifosato en Argentina y que los herbicidas inhibidores de la ALS pueden controlar biotipos resistentes e individuos más desarrollados.Conyza sumatrensis is one of the most problematic weeds in Argentina, with frequent control failures after glyphosate application. The objective of this research was to evaluate sensitivity of C. sumatrensis biotypes, at two growth stages (rosette and vegetative), to glyphosate and acetolactate synthase (ALS)-inhibiting herbicides. Dose-response experiments were performed using 0, 1/16, 1/8, 1/4, 1/2, 1, 2, 4, 8, and 16-fold of the recommended dose for each herbicide. At rosette stage, the resistance level for glyphosate was 9.8, while at the vegetative stage neither biotype was controlled with the recommended dose, with lower sensitivity of biotype R (RI = 2.3). Control of both biotypes using ALS-inhibiting herbicides was excellent at rosette stage, with lower doses than the recommended. At vegetative stage controls were good (80 %) with lower doses than recommended (0.16 X to 0.97 X), except for metsulfuron-methyl + chlorsulfuron in biotype S (1.75 X). These results may confirm the existence of a biotype resistant to glyphosate in Argentina and that ALS-inhibiting herbicides could control resistant biotypes and more developed individuals.Fil: Balassone, Federico Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Puricelli, Eduardo Carlos Jose Maria. Universidad Nacional de Rosario. Facultad de Cs.agrarias. Departamento de Producción Vegetal. Cátedra Terapeutica Vegetal; ArgentinaFil: Faccini, Delma Edith. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; Argentin
Anoda cristata control with glyphosate in narrow- and wide-row soyabean
Full text linkExperiments evaluated the effect of glyphosate rate and Anoda cristata density, on crop and weed biomass and weed seed production in wide (70 cm) and narrow rows (35 cm) glyphosate-resistant soyabean (Glycine max). Soyabean density was higher at 35 cm row spacing as an increase in planting rate in narrow-row soyabean is recommended for producers in Argentina. Soyabean biomass at growth stage V4 (four nodes on the main stem with fully developed leaves beginning with the unifoliate leaves) was higher when grown on narrow than in wide-rows but was not affected by the presence of A. cristata. At growth stage R5 (seed initiation – seed 3 mm long in a pod at one of the four uppermost nodes on the main stem, with a fully developed leaf and full canopy development), crop biomass was greater in narrow rows compared with wide rows with 12 plants m−2 of A. cristata. In narrow-row soyabean, a single application of a reduced rate of glyphosate maintained soyabean biomass at R5 and provided excellent weed control regardless of weed density. In wide-row soyabean control was reduced at the high weed density. Regardless of row spacing, A. cristata biomass and seed production were severely reduced by half of the recommended dose rate of glyphosate but the relationship between biomass and seed production was not altered. Glyphosate rates as low as 67.5 g a.e. ha−1 in narrow rows or 540 g a.e. ha−1 in wide rows provided excellent control of A. cristata. To minimize glyphosate use, planting narrow-row soyabean are effective where A. cristata density is low.Fil: Puricelli, Eduardo Carlos Jose Maria. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Faccini, Delma Edith. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Orioli, Gustavo Adolfo. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Sabbatini, Mario Ricardo. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentin
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
Determinación del período crítico, función de daño y control químico de Amaranthus quitensis Kunth en perejil (Petroselinum crispum (Mill.) A.W. Hill)
No full textTesis para optar al Grado de Magister Scientiae, presentado en la Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales. Maestría en Protección Vegetal, en 2009La producción de perejil para deshidratado ha tenido un importante desarrollo en los últimos tiempos en la Argentina, por ello es necesario disponer de información referida a la competencia del cultivo con las malezas y la eficacia de herbicidas preemergentes. Se realizaron estudios para determinar el período crítico de Amaranthus quitensis en perejil, cuantificar la influencia de la densidad de A. quitensis sobre el rendimiento del cultivo y la eficacia de un rango de dosis de herbicidas preemergentes (flurocloridona, linuron, metolacloro y prometrina) sobre A. quitensis, ajustando para cada herbicida la curva dosis-respuesta. El período crítico fue variable en los años estudiados y con la densidad de la maleza en una rango entre 3 y 44 días. Según la densidad de A. quitensis puede provocar pérdidas de rendimiento por encima del 73%. Los resultados demuestran que A. quitensis en condiciones ambientales normales puede reducir los rendimientos del cultivo de perejil si la maleza no es controlada en forma oportuna. Entretanto el control de la maleza fue excelente con todas las dosis de flurocloridona y los datos ajustaron a una función exponencial. En los otros herbicidas el ajuste fue loglogístico. Sólo con flurocloridona es posible reducir la dosis de uso manteniendo un buen control de la maleza. El resto de los herbicidas muestran adecuado control a dosis iguales o mayores a la de uso. Se concluye que manteniendo un adecuado período de control de A. quitensis y utilizando los herbicidas disponibles a la dosis determinada en esta tesis es posible realizar un manejo racional de la maleza maximizando el rendimiento del perejil.Parsley production for dehydration has shown a recent development in Argentina and information about weed competition with parsley and the knowledge of efficacy of premergence herbicides is lacking. Studies were conducted to determine the critical period for Amaranthus quitensis control in parsley and to quantify the influence of A. quitensis density on parsley yield and the efficacy of a range of doses of premergence herbicides (flurochloridone, linuron, metolachlor y prometrine) on A. quitensis , assessing for each herbicide the dose-response curve. The critical period was variable between years and weed densities, and ranged between 3 and 44 days. A. quitensis density can account for up to 73 % of yield loss. The results suggest that A. quitensis competition will reduce parsley yields under normal environmental conditions if weeds are not controlled in a timely manner. In the meantime weed control was excellent with all flurochloridone doses and data fitted an exponential model. In all other herbicides data fitted to a log-logistic model. Only with flurochloridone it is possible to reduce label dose keeping an excellent weed control. The other herbicides showed an adequate control at doses similar or higher than the label dose. It is concluded that keeping an adequate weed-free period of A. quitensis and using available at the dose determined in this thesis it is possible to perform a rational management of the weed maximizing parsley yield.EEA San PedroFil: Constantino, Armando. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Pedro; Argentin
Predación post-dispersiva de semillas de malezas en un agroecosistema pampeano
Full text linkLa predación es uno de los procesos que pueden causar pérdidas significativas de semillas, tanto en los bancos epigeos como en los hipogeos. En este trabajo se evalúan las pérdidas del banco superficial de semillas, de tres especies de malezas, ocasionadas por la predación producida por insectos, roedores y aves en un área de clausura con alta cobertura vegetal y en el área agrícola adyacente, durante el período otoñal 2015 y 2016. El estudio se realizó en el Campo Experimental J. F. Villarino (FAC-UNR), ubicado en la localidad de Zavalla S. F. Argentina (33º 01' lat. S). Se seleccionó un área de 3,12 ha, que comprende un espacio de 250x100 m de lote agrícola en período de barbecho, proveniente de monocultivo de soja sembrado bajo el sistema de siembra directa y un espacio adyacente de 250x25 m que corresponden a un área de clausura, donde no se realizan actividades agrícolas desde hace 31 años. Se localizaron 5 transectas, desde la clausura hasta el área de barbechos, distantes a 25 m unas de otras. En cada transecta se dispusieron 4 estaciones de muestreo ubicadas una en la clausura, otra en el borde y dos en el lote agrícola. En cada estación se colocaron al nivel de la superficie del suelo, cuatro bandejas plásticas de 18x11x2,5 cm, donde se colocaron 100 semillas de Commelia erecta, Echinochloa colona y Chenopodium album. Cada bandeja representa un tratamiento de predación y en su superfice se colocaron alambres tejidos de distintas tramas y con distinta arquitectura, de manera que puedan aislarse los factores de predación: total (TOT), insectos y roedores (I&R), sólo insectos (INS) y sin predación (SPR). Con los datos obtenidos se calculó la tasa de predación diaria de semillas: P=100 (1 - r 1/t). Para establecer la presencia y cuatificar la abundancia de predadores de semillas se utilizaron trampas "pitfall" para insectos, trampas Tomahawk para roedores y observación directa para aves. En las evaluaciones de insectos no se detectaron diferencias en la abundancia, riqueza, diversidad entre los distintos ambientes relevados; no obstante, la abundancia de detritívoros fue mayor en el rastrojo, la abundancia y riqueza de hormigas fue mayor en la clausura y la abundancia de predadores fue mayor en el área de borde. La abundancia, riqueza, diversidad y equitatividad de los roedores no difirieron entre ambos años de muestreo y tampoco entre fechas de muestreos dentro de cada año. El 49 por ciento de los roedores registrados corresponde a Cavia aperea y el 33 por ciento a Calomys musculinus, esta última es una especie reconocida por alimentarse de semillas de malezas. La abundancia de roedores fue mayor en la clausura respecto al rastrojo de soja; el borde presentó una situación intermedia. El 41 por ciento de los registros de aves corresponde a Passer domesticus y el 33 por ciento a Zenaida auriculata, especies cuya principal fuente de alimentación son las semillas. La abundancia de aves predadoras de semillas es mayor en las áreas de rastrojos y la riqueza es menor en la clausura. La diversidad y la equitatividad no difieren entre ambientes. La predación de semillas de malezas fue muy variable, las especies más predadas fueron E. colona en el 2015 y C. album en 2016. Los mayores predadores fueron los insectos y los roedores. Prácticas más respetuosas y sostenibles con el medio ambiente, como la promoción de la predación de semillas mediante el mantenimiento e incremento de los agentes biológicos de predación, podrían contribuir a la disminución de las aplicaciones de herbicidas en los agroecosistemas pampeanos, aunque esto requiere más investigación.The seed predation is one of the processes than can cause significant losses of seeds, both in epigeal and hypogeal banks. In this work was evaluate the losses of the superficial bank of deeds, of three species of weeds, caused by the predation produced by insects, rodents and birds in a closure area with high vegetation covedr and in the adjacent agricultural area, during the Autumnal period 2015 and 2016. The study was carried out in the J. F. Villarino Experimental Field (FCA-UNR), located in the town of Zavalla, S. F. Argentine (33º 01' lat. S). It's selected an area of 3.12 has, comprising a space of 250 x 100 m of an agricultural lot in the fallow period, from a monoculture of soybeans planted under the direct sowing system and adjacent space of 250 x 25 m that corresponds a closure area where not agricultural activities have been carried out for 31 years. Five transects were located, from the closure of the fallow area, 25 m away from each other. In each transect, ther were 4 light stations located one in the closure, another in the edge and two in the agricultural lot. In each station, four plastic trays of 18 x 11 x 2.5 cm palced at the level of the ground surface, where 100 seeds of Commelina erecta, Echinochloa colona and Chenopodium album were placed. Each tray represents a predation tratment and on its surface, they are placed in elastics of the same type as insects (TOT), insects and rodents (I&R), only insectos (INS) and without predation (SPR). With the daata obtained, the daily seed predation rate was calculated: P=100 (1 - r 1/t). To establish the presence and quantify the abundance of seed predators in the trap for insects, Tomahawk traps for rodents and direct observation for birds. In the evaluations of insects no differences in abundance, richness, diversity are detected between the different environments surveyed; nevertheless, the abundance of detritus in the stubble, the abundance, and abundance of ants was grater in the closure and the abundance of predator was greater in the edge area. The abundance, richness, diversity, and equitability of the rodents did not differ between years and between dates within each year. To another hand, the 49 per cent of rodents captured was Cavia aperea and 33 per cent to Calomys musculinus, this last one, is a sepecies recognizes by feeding of weeds. The abundance of rodents was grater in the closure with respect to the stubble of soybean; the edge presented an intermediate situation. The 41 per cent of bird records correspond to Passer domesticus and 33 per cent to Zenadia auriculata, which mostly consumes the main source of food. The abundance of predatory seed birds is grater in the stubble areas and the richness is lower in the closure. Diversity and equity do not differ between environments. The depredation of weed seeds was very variable; the mos depredated seed was E. colona in 2015 and C. album in 2016. The main predators were insects and rodents. More respectful and sustainable practices with the environment, such as the promotion of the prevention of seeds through the maintenance and increase of biological predation agents, which may contribute to the reduction of herbicide applications in the Pampean agroecosystems, although this it requires more investigation.Fil: Apellido, Nombre. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Heredia Pinos, Marcos Raúl. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; Argentin
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
- …
