Comparação da Sensibilidade ao Glyphosate de Populações de Euphorbia davidii

Euphorbia davidii (Euphorbiaceae) is a summer annual weed present in the Province of Buenos Aires, Argentina. The aim of this study was to compare the sensitivity to glyphosate of different populations of Euphorbia davidii. Twotechniques were used: a seed bioassay and shikimate determination in glyphosa tetreated plants. Germination rates of seeds belonging to the populations from Espartillar, Barrow, Olavarria and Azul exposed to different concentrations of glyphosate were compared. Plants from the same locations treated with glyphosate were evaluated to determine shikimate levels. The most sensitive population was from Espartillar, with a CE50 (average effective concentration) of 4.00 g e.a. L-1. Based on this finding, the resistance index for each population was 1.76, 2.39 and 2.48 for Azul, Olavarria and Barrow respectively. Regarding glyphosate-treated plants in which shikimate levels were determined, a significant increase in the concentration of this metabolite was only observed in the population from Espartillar. Accumulation of shikimate was not detected in the other groups. These results show differential sensitivity to glyphosate of the evaluated populations.Euphorbia davidii (Euphorbiaceae) é uma planta infestante de ciclo anual primaveril-estival presente na Província de Buenos Aires, Argentina. O objetivo deste estudo foi comparar a sensibilidade ao glyphosate de diferentes populações de Euphorbia davidii. Para isso, foram usadas duas técnicas: bioensaio com sementes e determinação dos níveis de chiquimato nas plantas tratadas com glyphosate. Fez-se uma comparação da germinação de sementes de populações provenientes de Espartillar, Barrow, Olavarria e Azul, expostas a diferentes concentrações de glyphosate. Procedeu-se à determinação dos níveis de chiquimato em plantas provenientes das mesmas localidades e tratadas com o herbicida. A população mais sensível foi a de Espartillar, com uma CE50 (concentração efetiva média) de 4,00 g a.e. L-1. Com base neste valor, o índice de resistência de cada local de origem foi de 1,76 , 2,39 e 2,48 para Azul, Olavarría e Barrow, respectivamente. Entre as plantas tratadas, em que os valores de chiquimato foram determinados, observou-se apenas aumento significativo na concentração desse metabólito na população de Espartillar. Nas outras populações não foi identificada qualquer acumulação de chiquimato. Os resultados mostram a sensibilidade diferencial ao glyphosate das populações avaliadas.Fil: Núñez Fré, Federico Roberto. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Juan, Victor Fabian. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Yanniccari, Marcos Ezequiel. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Barrow; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Saint André, Horacio María. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Fernandez, R.R.. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomía; Argentin

Control of Euphorbia dentata with different formulations of glyphosate in transgenic soybean resistant to glyphosate

Euphorbia dentata es una maleza de difícil control y altamente competitiva en los cultivos de soja en Ia zona centro de Ia Provincia de Buenos Aires, Argentina. EI desarrollo de soja transgénica resistente a glifosato (RG) permite explorar nuevas técnicas de control químico de malezas, principalmente sobre especies en Ias cuales los herbicidas tradicionalmente usados no resultan eficientes. EI objetivo deI presente trabajo fue evaluar Ia eficacia de diferentes formulaciones de glifosato para el control de E. dentata en soja RG. EI ensayo fue realizado en el partido de Azul, Pc ia. de Buenos Aires, durante Ias campafías agrícolas 99/00 y 00101 utilizando soja Cv. AX 4100 RG Ycon una infestación de E. dentata de 135 pl/m'. Los tratamientos consistieron en Ia aplicación de tres dosis de glifosato (720, 1260 Y 1620 g/ha eq.acido) utilizando tres formulaciones comerciales deI mismo ingrediente activo existentes en Argentina: formulación I (sal isopropylamina SL 48%, Ru), formulación 2 (sal monoamónica WG 74,7%, Ru_M), formulación 3 (sal isopropylamina tecnología transorb SL 48%, Ru_F), testigo limpio y testigo enmalezado. Las aspersiones fueron realizadas cuando Ia maleza se encontraba en un estado de 4 hojas desarrolladas, con un caudal equivalente a 100 L/ha, utilizando un equipo manual de CO2• Se evaluó eficacia de control de Ia maleza y el rendimiento deI cultivo. Todas Ias formulaciones de glifosato lograron altos niveles de control (superiores aI 85%) con Ia máxima dosis utilizada, no difiriendo significativamente entre sí. La formulación 3 (Ru_F) presentó alta eficacia aún con Ia dosis de 720 g/ha donde el resto de Ia formulaciones logró solo controles parciales (50 y 60%). En cuanto aI rendirniento, todos los tratamientos difirieron significativamente deI testigo erunalezado cuya productividad fue de aproximadamente 2500 kg/ha. Los tratamientos que lograron los máximos niveles de control no difirieron significativamente deI testigo limpio que tuvo un rendimiento de 4000 kglha.Euphorbia dentata is a highly competitive and difficult to control weed in soybean crops in the central are a of Buenos Aires Province, Argentina. Development of transgenic soybean resistant to glyphosate (GR) allows exploration of new techniques of chemical weed control, mainly where the herbicides traditionalJy used are inefficient. The objetive of this . research was to evaluate the effectiveness of Euphorbia dentata control with different formulations of glyphosate in soybean GR. The trial was carried out in Azul district, province of Buenos Aires, during the 99/00 and 0010 I agricultural seasons using soybean cv. AX 4100 GR and with an infestation of E. dentata of 135 pl/m" The treatments consisted in the application of three doses of glyphosate (720, 1260 and 1620 g/ha acid equivalent) using three commercial formulations of the same active ingredient available in Argentina: formulation 1 (isopropylanmine salt SL 48%, Ru) , formulation 2 (monoamonic salt WG 74,7%, Ru_M), formulation 3 (isopropylamine salt with transorb technology SL 48%, Ru_F), weeded control and non weeded, where the weeds were removed manually. The sprayings were performed when the weed had developed 4 true leaves and with a volume equivalent to 100 Llha, using a CO2 manual equipment. Weed control and crop yield were evaluated. Ali the glyphosate formulations obtained high levels of control (more than 85 %) with the use ofthe maximum doses but did not differ significantly among themselves. The isopropylamine salt formulation (Ru_F) showed high efficiency even with a doses of 720 g/ha, whereas the other formulations only obtained partial controls (50 and 60%). Concerning yield, ali the treatments differed significantly from the weeded control whose productivity was about 2500 kglha. The treatments which obtained the maximum levels of control did not differ significantly from the control without weeds which had a yield of 4000 kg/ha.