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Suscetibilidade de genótipos de Lolium multiflorum ao herbicida glyphosate
Dors, C.A.;Christoffoleti, P.J.;Sanchotene, D.M.;Dias, A.C.R.;Manfron, P.A.;Dornelles, S.H.B.;
Planta Daninha , 2010, DOI: 10.1590/S0100-83582010000200020
Abstract: this work aimed to evaluate the degree of tolerance of italian ryegrass genotypes to the herbicide glyphosate. thus, four experiments were installed, one for each phenological stage (two leaves, four tillers, pre-flowering, and grain formation). the treatments consisted of the combination of the two genotypes and six rates of glyphosate (240; 480; 960; 1,920; 3,840 and 7,680 g a.e. ha-1) and a check without glyphosate application, in a complete randomized block design and four replications. the parameters analyzed were control percentage and shoot dry biomass. results were submitted to analysis of variance and subsequently adjusted to non-linear log of dose-response curves, and from these models control values were calculated at 50, 80, 90 and 99%. the italian ryegrass genotypes presented differential susceptibility to the herbicide glyphosate, with the tetraploid genotype being more tolerant to the herbicide than the diploid. the degree of differential tolerance, measured by the differential tolerance factor between the genotypes, is 1.6 times the glyphosate dose in the tetraploid genotype compared to the diploid genotype. the phenological stages of plant development of both the genotypes studied affected the degree of tolerance to glyphosate. the variable shoot dry biomass presented the same differential tendency between the diploid and tetraploid genotypes presented by the parameter visual control percentage.
Identifica??o de biótipos de azevém (Lolium multiflorum) resistentes ao herbicida glyphosate em pomares de ma??
Vargas, L.;Roman, E.S.;Rizzardi, M.A.;Silva, V.C.;
Planta Daninha , 2004, DOI: 10.1590/S0100-83582004000400017
Abstract: glyphosate is a wide spectrum herbicide used for over 15 years in apple orchards in vacaria-rs for weed control in rows of trees. usually, 3 to 4 applications per year are made at a rate of 720 to 1080 g a.e. glyphosate ha-1 (2 to 3 l ha-1 of commercial product). ryegrass (lolium multiflorum) is a common weed in orchards and traditionally sensitive to glyphosate. however, in the last years, some ryegrass plants have not been found to show significant toxicity symptoms after treatment with glyphosate, suggesting that they acquired resistance to this product. to evaluate the response of a ryegrass plant population to glyphosate, one field and two greenhouse experiments were carried out. the field experiment treatments had increasing rates of glyphosate (0; 360; 720; 1,440; 2,880; 5,760 and 11,520 g a.e. ha-1), in addition to the herbicides paraquat, glufosinate-ammonium, haloxyfop and diclofop-methyl as standards, sprayed at two different vegetative growth stages of ryegrass. the greenhouse experiments had increasing rates of glyphosate (0; 360; 720; 1,440; 2,880 and 5,760 g a.e. ha-1) plus the above listed check herbicides sprayed on biotypes considered resistant and on plants of one susceptible biotype. in the second greenhouse experiment, glyphosate rates (720; 1,440; 2,880; 720 + 720 and 720 + 1,440 g a.e. ha-1) were sprayed in single and sequential applications, in addition to the herbicides paraquat, glufosinate-ammonium, haloxyfop, clethodim, sethoxydim, diclofop-methyl, fenoxaprop, fluazifop, paraquat + diuron, atrazine + simazine, trifluralin, and metolachlor. toxicicity to the herbicides was assessed at 15, 30 and 45 dat (days after treatment). overall, the field and greenhouse experiment results showed that the susceptible biotype is easily controlled by glyphosate and by the other postemergence herbicides tested, independent of the vegetative growth stage. in addition, the results showed that the resistant biotype, similarly to the susceptible biotype, is
Altera??o das características biológicas dos biótipos de azevém (Lolium multiflorum) ocasionada pela resistência ao herbicida glyphosate
Vargas, L.;Roman, E.S.;Rizzardi, M.A.;Silva, V.C.;
Planta Daninha , 2005, DOI: 10.1590/S0100-83582005000100018
Abstract: the identification of ryegrass biotypes resistant to glyphosate is causing changes in weed management in apple orchards. three experiments were carried out to determine the gr50 of the biotypes, to grass herbicides and dry matter accumulation. the first experiment tested different rates of glyphosate. their effects on gr50 dry matter accumulation by the biotype were assessed. in the second experiment different rates of glyphosate and grass herbicides were tested: glyphosate, haloxyfop-r, diclofop, fluazifop-p, fenoxaprop-p and paraquat. a third experiments was carried out under glasshouse conditions to determine the curve of dry matter accumulation. the results showed gr50 of 287.5 and 4,833.5 g e. a. ha-1 of glyphosate for the sensitive and resistant biotypes, respectively. the results showed that the resistant factor (rf) was 16.8 and that the resistance mechanism alters the biological characteristics of the resistant biotype affecting its sensitivity to grass herbicides.
Anatomia foliar de Lolium multiflorum sensível e resistente ao glyphosate
Galvani, J.;Rizzardi, M.A.;Carneiro, C.M.;Bianchi, M.A;
Planta Daninha , 2012, DOI: 10.1590/S0100-83582012000200021
Abstract: this work aimed to contribute to the anatomical knowledge of the species lolium multiflorum and to observe possible changes that may elucidate the mechanism that confers its resistance to the herbicide glyphosate. thus, an experiment was conducted using four biotypes of this species with distinct sensitivities to the herbicide glyphosate: one susceptible (b1s) and three resistant biotypes (b2r, b3r and b4r). analyses were conducted on the transverse and longitudinal sections of the vegetative organs of the plants at the tillering stage. anatomically, ryegrass is characterized as having a large number of stomata and buliform cells as well as homogeneous mesophylls constituted only of palisade cells compactly distributed. comparatively, no evident morphological differences occur that can be used to distinguish sensitive from resistant biotypes; however, the resistant biotypes, especially b3r b4r, presented higher stomatal density, compared to the others. still, the resistant biotypes had a higher amount of intercellular spaces in the mesophyll and vascular bundles with a smaller amount of phloem compared to the xylem, which, because of their functions in the plants, may contribute to the lower sensitivity to the herbicide.
Heran?a da resistência de azevém (Lolium multiflorum) ao glyphosate
Vargas, L.;Moraes, R.M.A.;Berto, C.M.;
Planta Daninha , 2007, DOI: 10.1590/S0100-83582007000300016
Abstract: glyphosate is a non-selective herbicide used to control weeds. azevem plants, which are tolerant to glyphosate, have been identified in rio grande do sul, where they are rapidly becoming predominant. the objective of this work was to identify inheritance type, number of genes conferring resistance, and the degree of resistance in azevem plants. reciprocal crossings between sensitive and resistant plants have been carried out to obtain f1 seeds which were crossed among themselves to obtain f2 plants .herbicide containing 720 g ha-1 was applied on the f1, f2, rcr, rc and parent plants to estimate segregation. to evaluate the degree of resistance of the f1 plants, resistant and sensitive parents were sprayed with increasing rates of glyphosate (0, 360, 720, 1.440 and 2.880 g ha-1). f1 plants showed intermediate response to the resistant and sensitive biotypes, indicating that allelic interaction is of the incomplete dominance type. f2 plants showed a tendency for segregation 3:1, indicating that resistance to glyphosate is controlled by a semi-dominant gene.
Aspectos morfofisiológicos de biótipos de azevém (Lolium multiflorum) sensíveis e resistentes ao glyphosate
Galvan, J;Rizzardi, M.A;Scheffer-Basso, S;
Planta Daninha , 2011, DOI: 10.1590/S0100-83582011000500018
Abstract: ryegrass has a high potential for infestation in crops and orchads and its control with glyphosate has been limited due to the existence of herbicide-resistant biotypes. the objective of this work was to compare four ryegrass biotypes collected from different regions in the state of rio grande do sul, brazil, to test the hypothesis that morphophysiological aspects and phenology are linked to resistance. the experiment was conducted in a greenhouse, where four biotypes, one susceptible (b1s, passo fundo) and three resistant to glyphosate (b2r, santa maria; b3r, julio de castillos; b4r, vacaria) were collected at 126, 147, 168 and 189 days of age. biotype b1s showed 21 days in advance of flowering in relation to the other biotypes. biotype b4r produced significantly more leaves (43 per plant), tillers (14 per plant), ears (14 per plant), seeds (3484 per plant) and total dry matter (roots + shoot = 13.8 g per plant). it is concluded that sensitive biotypes cannot be distinguished from the resistant ones only by morphological aspects related to vigor.
Análisis de la sensibilidad de biotipos de Lolium multiflorum a herbicidas inhibidores de la enzima ALS, ACCasa y Glifosato Sensitivity analysis of Lolium multiflorum biotypes to Glyphosate, ACCase and ALS-inhibiting herbicides
P. Diez De Ulzurrun,M.I. Leaden
Planta Daninha , 2012, DOI: 10.1590/s0100-83582012000300024
Abstract: A pesar de los avances logrados en el control de las malezas con el uso de herbicidas, el manejo de las mismas no se simplificó, sino que, al contrario, surgieron nuevos desafíos, como la aparición de resistencia a herbicidas. En 2007, se reportó en Lolium multiflorum el segundo caso de resistencia a glifosato detectado en Argentina. En el sudeste de la provincia de Buenos Aires se registraron fallas de control a campo en poblaciones de Lolium multiflorum debido a su resistencia a distintos herbicidas de las familias de los inhibidores de ALS y de ACCasa y al herbicida glifosato. El objetivo de este estudio fue caracterizar el nivel de resistencia a ciertos herbicidas inhibidores de la ALS y de la ACCasa y al glifosato en una población de L. multiflorum de Lobería (Bs As, Argentina) supuestamente resistente (LmR). Se realizaron bioensayos en cajas de Petri y se determinó la GR50 mediante la variación en la longitud de coleoptile. Las curvas de dosis-respuesta se obtuvieron por medio de la ecuación log-logística. El biotipo LmR presentó resistencia múltiple a herbicidas con tres modos de acción diferentes: glifosato, inhibidores de ALS y de ACCasa. Dicho ensayo demostró la aparición de un biotipo de L. multiflorum con resistencia a múltiples principios activos. Despite progress in weed control using herbicides, management has not been simplified, but new challenges such as herbicides resistance have arisen. In 2007, a Lolium multiflorum population resistant to glyphosate was reported, as the second case of glyphosate resistant weeds in Argentina. In the southeast of Buenos Aires province, control failures in populations of L. multiflorum to different families of herbicide such as ALS and ACCase inhibitors and to glyphosate at field level have been registered. The aim of this study was to characterize the level of resistance to certain herbicides inhibitors of ALS, ACCase and glyphosate in a putatively resistant (LmR) population of L. multiflorum of Loberia (Buenos Aires, Argentina). Bioassays were conducted in Petri dishes and the GR50 was determined by the length of coleoptile. Curves dose-response were obtained using the log-logistic equation. The LmR biotype survived under multiple herbicides of three different modes of action, glyphosate, ALS and ACCase inhibitors. This test showed the appearance of a biotype of L. multiflorum with resistance to multiple active ingredients.
Produ o animal em pastagem natural e pastagem sobre-semeada com espécies de esta o fria com e sem o uso de glyphosate = Animal production in natural pasture and pasture overseeded with cool season species with and without the use of glyphosate
Fábio Cervo Garagorry,Fernando Luiz Ferreira de Quadros,Magdalena Reschke Lajús Travi,Duílio Guerra Bandinelli
Acta Scientiarum : Animal Sciences , 2008,
Abstract: Objetivou-se avaliar a produ o animal de novilhos e vegetal de campo natural e de campo natural sobre-semeado com azevém (Lolium multiflorum), trevo branco (Trifolium repens) e cornich o (Lotus corniculatus) com e sem a utiliza o do herbicida glyphosate. Os tratamentos foram: CN – campo nativo, com ro ada anual; CNI – campo nativo com sobre-semeadura, aduba o e ro ada anual; G1 – Idem ao CNI com aplica o de herbicida no primeiro ano; G3 – idem ao G1 com supress o da vegeta o natural com herbicida no segundo e terceiro ano; GA3 – Idem ao G3 com aduba o duplicada nos três anos. O delineamento experimental foi blocos completamente casualizados com duas repeti es. Os resultados apresentados s o do terceiro anode avalia o. Para ganho médio diário, houve diferen as (p £ 0,1) entre tratamentos e períodos, que variaram de 0,214 kg animal-1 dia-1 em CN a 1,406 para os tratamentos com introdu o de espécies. Quanto à variável ganho por área, os ganhos variaram de 84 a 410 kg PV ha-1. As cargas variaram de 283 a 679 kg PV ha-1. O uso do herbicida n o apresentou efeitos sobre a produ o; e a introdu o de espécies de esta o fria por sobre-semeadura melhorou a produ o animal emCN, que possibilitou a colheita de maiores ganhos animal-1 dia-1 e por área. This study evaluated animal production of steers and pasture production of natural grassland and grassland overseeded withItalian ryegrass (Lolium multiflorum), white clover (Trifolium repens) and birdsfoot trefoil (Lotus corniculatus), with and without the use of glyphosate herbicide. Treatments consisted of: NG –natural grassland, with annual mowing; ING – natural grassland with overseeding, fertilizing and annual mowing; G1 – Same ING, but with glyphosate application in the first year; G3 – same as G1, with suppression of natural vegetation using herbicide in the second and third years; GF3 – same as G3, with doubled fertilizing in the three years. The experimental design consisted of completely randomized blocks with two replications. The results presented are from the third year of evaluation. For average daily weight gain, there were differences (p £ 0.1) among treatments and periods, varying from 0.214 kg animal-1 day-1 in NG to 1.406 for the treatments with introduction of species. Live weight gain per area varied from 84 to 410 kg of LW ha-1. The stocking rates varied from 283 to 679 kg of LW ha-1. The herbicide did not present effects on production; andintroduction of cool season species by overseeding improved animal production in NG, resulting in higher animal performance per animal and per area.
Transloca??o do glyphosate em biótipos de azevém (Lolium multiflorum)
Ferreira, E.A.;Santos, J.B.;Silva, A.A.;Oliveira, J.A.;Vargas, L.;
Planta Daninha , 2006, DOI: 10.1590/S0100-83582006000200021
Abstract: this work evaluated foliar absorption and glyphosate translocation in italian ryegrass (lolium multiflorum) susceptible and resistant biotypes, 14c-glyphosate was applied by using a precision micro syringe, and adding 10 μl of solution on the adaxial side of the first leaf with ligule totally visible, when italian ryegrass plants showed 3 tillers. the quantity of glyphosate absorbed and translocated was evaluated through a liquid scintilation spectrometer by measuring radiation emitted by 14c-glyphosate at 2, 4, 8, 16, 32 and 64 hours after application. the roots and aerial part were analyzed as well as the leaf where application was performed and the solution used to wash the leaf. glyphosate absorption speed was similar in both italian ryegrass biotypes, with over 50% of herbicide absorption in the first 8 hours after application. up to 64 hours, higher retention (81.64%)of glyphosate was observed in the resistant biotype, while only 55% was retained in the susceptible biotype. in the remaining aerial part and roots, a higher amount of glyphosate was absorbed by the susceptible biotype, indicating higher capacity of its translocation. after 64 hours of application, only 6%, of glyphosate was found in the plants, on average indicating that most of the product could be exuded. it could be concluded that italian ryegrass sensitivity to glyphosate can be attributed to higher translocation capacity of this herbicide by susceptible biotypes.
Glyphosate translocation in herbicide tolerant plants Transloca o do glyphosate em plantas tolerantes ao herbicida  [cached]
L Galon,E.A Ferreira,I Aspiazú,G Concen?o
Planta Daninha , 2013, DOI: 10.1590/s0100-83582013000100021
Abstract: The objective of this study was to evaluate glyphosate translocation in glyphosate-tolerant weed species (I. nil, T. procumbens and S. latifolia) compared to glyphosate-susceptible species (B. pilosa). The evaluations of 14C-glyphosate absorption and translocation were performed at 6, 12, 36 and 72 hours after treatment (HAT) in I. nil and B. pilosa, and only at 72 HAT in the species T. procumbens and S. latifolia. The plants were collected and fractionated into application leaf, other leaves, stems, and roots. In S. latifolia, approximately 88% of the glyphosate remained in the application leaf and a small amount was translocated to roots at 72 HAT. However, 75% of the herbicide applied on T. procumbens remained in the leaf that had received the treatment, with greater glyphosate translocation to the floral bud. It was concluded that the smaller amount of glyphosate observed in S. latifolia and T. procumbens may partly account for their higher tolerance to glyphosate. However, I. nil tolerance to glyphosate may be associated with other factors such as metabolization, root exudation or compartmentalization, because a large amount of the herbicide reached the roots of this species. Objetivou-se neste estudo avaliar a transloca o de glyphosate em plantas tolerantes (Ipomoea nil, Tridax procumbens e Spermacoce latifolia) e suscetível (Bidens pilosa) a esse herbicida. As avalia es de absor o e transloca o do 14C-glyphosate em I. nil e B. pilosa foram efetuadas às 6, 12, 36 e 72 horas após a aplica o do herbicida (HAT), e em T. procumbens e S. latifolia, às 72 HAT. As plantas foram coletadas e fracionadas em: folha de aplica o, demais folhas, caules e raízes; em T. procumbens e S. latifolia, avaliou-se a presen a do produto na inflorescência da planta. Em S. latifolia, aproximadamente 88% do glyphosate permaneceu na folha de aplica o, e pequena quantidade translocou para as raízes. Todavia, em T. procumbens, 75% do herbicida permaneceu na folha que recebeu a aplica o, observando-se maior transloca o na inflorescência em rela o às raízes. Conclui-se que a menor transloca o do glyphosate observada em S. latifolia e T. procumbens pode ser um dos fatores responsáveis pela maior tolerancia dessas espécies ao herbicida, ao passo que em I. nil a metaboliza o, a exsuda o radicular ou a compartimentaliza o podem favorecer a tolerancia, já que grande quantidade do produto atingiu as raízes da espécie.
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