ABSTRACT Second-generation glyphosate-tolerant maize (Roundup Ready 2, RR2) is characterised by the expression of the cp4epsps gene. Despite some studies suggesting possible undesirable effects from the application of glyphosate in RR2 maize, other reports have demonstrated glyphosate selectivity for RR2 plants, with minor damage symptoms, if any, and with no negative effects on the chlorophyll indices. The aim of this study was to evaluate the effect of different types of glyphosate management, formulations and rates of application on chlorophyll indices and the agronomic performance of an RR2 maize genotype expressing the cp4epsps gene. Five experiments were conducted in a full factorial design (2 x 5 x 5) to evaluate two types of management, two formulations and five rates of glyphosate. Damage symptoms, chlorophyll indices and variables related to agronomic performance (plant height, stem diameter, yield and 100-grain weight) were evaluated. Similar crop responses were found for each of the glyphosate formulations (potassium salt and isopropylamine salt) and types of management (single application and sequential application) under test, indicating that the use of glyphosate-based commercial products affords flexibility in terms of formulation and frequency of application. Glyphosate formulated as potassium salt or isopropylamine salt and applied to RR2 maize either in a single application (full rate) or in two sequential applications (each at half rate) has a similar effect and may therefore be used without distinction. However, it is important to consider the rate of application since high rates of glyphosate (especially greater than 1,440 g ae ha-1) may affect the development and production of RR2 maize. Secondgeneration Second generation glyphosatetolerant tolerant Roundup 2 RR cpepsps cp epsps gene plants symptoms any ( plant height diameter 100grain grain 100 weight evaluated test glyphosatebased based distinction However especially 1440 1 440 1,44 ha1 ha ha-1 10 144 44 1,4 ha- 14 4 1,

Abstract: Background: Chickpeas (Cicer arietinum) are an important type of pulse whose production is hindered by poor weed control. Objective: To assess lactofen selectivity levels and to uncover tolerance mechanisms in commercial genotypes. Methods: Four genotypes and weed species were grown under controlled-environment conditions and subjected to lactofen dose-response assays (11.2–2,880 g a.i. ha−1). Visual evaluations performed until 35 days after application, when biomass was quantified and selectivity indexes obtained using regression analysis. Following 14C-lactofen application, absorption and translocation were assessed until 168h after treatment (HAT), when chickpea plants were washed to remove the unabsorbed herbicide or subjected to autoradiography and tissue combustion. Lastly, 14C-lactofen was applied and metabolites extracted at 96 HAT, and their retention factors (Rf) determined by thin layer chromatography and radioscanner reading. Results: Tridax procumbens and Amaranthus spinosus were highly susceptible to lactofen. Chickpea genotypes tolerated lactofen at the highest labelled used rate in soybeans (180 g a.i. ha−1). Lactofen absorption was high (88.1%–94.6%) and translocation was limited (< 2.5%) across genotypes - a similar trend observed in susceptible species, and hence are not implicated in lactofen tolerance. One main metabolite was found in chickpea genotypes, accounting for 12.5%–19.4% of applied radioactivity; the chickpea genotype with the highest tolerance level (BRS Cicero) was the only one in which two metabolites were quantified. Altogether, these results suggest that lactofen tolerance in chickpeas could be conferred by enhanced herbicide metabolism. Conclusions: Lactofen could become an option for selective, post-emergence weed control in chickpeas. Abstract Background Cicer arietinum Objective Methods controlledenvironment controlled environment doseresponse dose response 11.2–2,880 1122880 11 2 880 (11.2–2,88 ai i a.i ha−1. ha1 ha ha−1 . 1 ha−1) 3 application analysis 14Clactofen Clactofen 14C C h HAT , (HAT) combustion Lastly 9 Rf (Rf reading Results 180 (18 88.1%–94.6% 881946 88 94 6 (88.1%–94.6% < ( 2.5% 25 5 125194 12 19 4 12.5%–19.4 radioactivity BRS Cicero Altogether metabolism Conclusions selective postemergence post emergence 11.2–2,88 112288 (11.2–2,8 ha− (HAT 18 (1 88.1%–94.6 88194 8 (88.1%–94.6 2.5 12519 12.5%–19. 11.2–2,8 11228 (11.2–2, 88.1%–94. 8819 (88.1%–94. 2. 1251 12.5%–19 11.2–2, 1122 (11.2–2 88.1%–94 881 (88.1%–94 125 12.5%–1 11.2–2 112 (11.2– 88.1%–9 (88.1%–9 12.5%– 11.2– (11.2 88.1%– (88.1%– 12.5% 11.2 (11. 88.1% (88.1% 12.5 11. (11 88.1 (88.1 12. 88. (88. (88 (8

Resumen Los herbicidas inhibidores de la ALS en combinación con inhibidores de la ACCase pueden ser utilizados como alternativa al glifosato en el control de malezas en soya RR2/STS. En el presente estudio se evalúa la eficacia de herbicidas inhibidores de la ALS, en asociación con haloxyfop, en el control de malezas para aplicación en post-emergencia (V4) de soya RR/STS. El experimento se realiza en la campaña 2017/18 en Piracicaba, Sao Paulo (SP), Brasil. Se utiliza el cultivar BMX Garra RR2/STS y los tratamientos fueron compuestos por la aplicación de herbicidas inhibidores de la ALS en asociación con haloxyfop. El diseño experimental fue de bloques al azar, con cuatro repeticiones. Se evaluaron control y masa seca de malezas, nivel de daño en las plantas de soya y productividad. Los datos fueron sometidos al análisis de varianza y las medias de los tratamientos fueron comparados por el test de Tukey. Se observaron síntomas visuales de daño en las plantas de soja, principalmente para aplicación de nicosulfuron y nicosulfuron + cloransulam. La productividad fue mayor en todos los tratamientos con herbicidas en comparación con el control sin deshierbe manual. Las asociaciones entre herbicidas inhibidores de la ALS y haloxyfop aplicadas en post emergencia (V4) del cultivar de soya BMX Garra RR2/STS fueron eficaces en el control de malezas.

Abstract It is believed that ALS inhibitor herbicides in combination with ACCase inhibitors can be used as an alternative to glyphosate in weed control in RR2/STS soybeans. In the present study, the efficacy of ALS inhibitor herbicides, in combination with haloxyfop, is evaluated in the control of weeds for post- emergence application (V4) of RR/STS soybeans. The experiment is carried out in the 2017/18 season in Piracicaba, Sao Paulo (SP), Brazil. The cultivar BMX Garra RR2/STS is used, and the treatments were composed by the application of ALS inhibitor herbicides in association with haloxyfop. The experimental design was a randomized block with four replications. Were evaluated control and dry mass of weeds, symptoms of injury in soybean plants and yield. The data were submitted to analysis of variance and the means of the treatments were compared by the Tukey test. Visual symptoms of injury were observed in soybean plants, mainly for the application of nicosulfuron and nicosulfuron + cloransulam. Soybean yield was higher in all herbicide treatments compared to the control without weeding. Associations between ALS inhibitor herbicides and haloxyfop applied post-emergence (V4) of soybean cultivar BMX Garra RR2/ STS were effective in weed control.

RESUMEN El índice de selectividad es una forma de evaluar el efecto selectivo de un herbicida para un cultivo determinado mediante la observación de sus efectos sobre el cultivo y las malezas. El objetivo fue obtener el índice de selectividad del herbicida indaziflam en el cultivo de caña de azúcar IACSP95-5000 en función de cinco malezas en dos texturas de suelo diferentes. El experimento se realizó en un invernadero en Piracicaba, São Paulo, Brasil. Los tratamientos consistieron en dosis de indaziflam (0; 12,5; 25; 50; 100; 200; 400; 800 y 1,600 g ai ha-1), aplicadas en pre-emergencia de la caña de azúcar y de las malezas Urochloa decumbens, Urochloa plantaginea, Digitaria horizontalis, Panicum maximum y Rottboellia cochinchinensis. En suelo franco arenoso, 25 g de ia ha-1 proporcionaron un control del 100% para todas las malezas. En suelo arcilloso, para D. horizontalis la reducción del 90% en la masa seca total (ED90) se obtuvo a 25 g ai ha-1, para R. cochinchinensis a 193 g ai ha-1, para U. plantaginea a 152 g ai ha-1, para P. maximum a 124 g ia ha-1, y para U. decumbens a 94 g ia ha-1. Indaziflam fue selectivo para IACSP95-5000 caña de azúcar en ambos suelos, con 10% de reducción de masa seca (ED10) a 137 g ia ha-1 para suelo con textura franco arenosa y 353 g ia ha-1 para suelo arcilloso. El índice de selectividad fue superior a 1 para todas las malezas en suelo arcilloso. No fue posible obtener el índice de selectividad para suelos franco arenosos debido a la susceptibilidad de las malezas al herbicida.

ABSTRACT Selectivity index is a way of assessing the discrimination of herbicide to a given crop by observing its effects on the crop and the weeds. The aim was to obtain the selectivity index of indaziflam herbicide to sugarcane cultivar IACSP95-5000 as a function of five weed species in two soils textures. The experiment was carried out in a greenhouse at Piracicaba, São Paulo, Brazil. The treatments consisted of indaziflam doses (0; 12.5; 25; 50; 100; 200; 400; 800 and 1,600 g of the active ingredient (ai) ha-1), applied in pre-emergence of the sugarcane and of the weeds Urochloa decumbens, Urochloa plantaginea, Digitaria horizontalis, Panicum maximum and Rottboellia cochinchinensis. In sandy loam soil, a 100% control for all weeds was provided at 25 g ai ha-1. In clay soil, for D. horizontalis the 90% reduction in total dry mass (ED90) was obtained at 25 g ai ha-1, for R. cochinchinensis at 193 g ai ha-1, for U. plantaginea at 152 g ai ha-1, for P. maximum at 124 g ai ha-1, and for U. decumbens at 94 g ai ha-1. Indaziflam was selective to IACSP95-5000 in both soils, with 10% of reduction in dry mass (ED10) at 137 g ai ha-1 for soil with a sandy loam texture and 353 g ai ha-1 for clay soil. The selectivity index was higher than 1 for all weeds in clay soil. It was not possible to obtain the selectivity index for sandy loam soil due to species susceptibility to the herbicide.

Abstract Background Achieving satisfactory weed control levels in black oat (Avena strigosa) fields is often difficult, owing to the limited number of registered herbicide molecules. Objective To determine novel options for selective, post-emergence chemical weed control in this crop. Methods Eight herbicide treatments were sprayed in the field onto black oat plants at the tillering stage to evaluate crop safety and control of Conyza spp. and Gamochaeta americana, two major weeds of Brazilian black oats. A separate trial was conducted to further assess herbicide safety in a controlled-environment setting, and mesotrione selectivity was then re-evaluated separately in the greenhouse during the following growing season. Crop phytotoxicity was determined using biomass production both in the field and in greenhouse trials. Results Mesotrione, bentazon, 2,4-D, and a 2,4-D+bentazon tank-mix produced light symptoms of crop phytotoxicity, from which plants quickly recovered. Conyza spp. control was achieved via applications of mesotrione (192 g a.i. ha-1), metsulfuron-methyl (3.9 g a.i. ha-1), and a 2,4-D + bentazon tank-mix (502.5 g a.e. ha-1 + 720 g a.i. ha-1, respectively), whereas proper G. americana control was only achieved via applications of either mesotrione or metsulfuron-methyl. Biomass accumulation by black oat plants in the greenhouse was similar across mesotrione-treated and untreated plants. Conclusions Mesotrione could become an option for selective, post-emergence weed control in black oat fields, aiding in the fight against multiple herbicide-resistant Conyza spp. populations which are widespread across major black oat-growing areas in Brazil.

RESUMEN El metsulfurón se usa ampliamente para el manejo de malezas, sin embargo, el efecto residual en los cultivares de soja STS es desconocido. El objetivo de este trabajo fue evaluar el efecto residual del herbicida metsulfurón en los cultivares de soja BMX Garra RR2/STS y M 6410 IPRO (no-STS). El metsulfurón se aplicó a una dosis de 2,4 g i.a. ha-1, en la pre-siembra de soja. El diseño experimental fue completamente aleatorio en un esquema factorial de 2x5 con cuatro repeticiones (primer factor: dos cultivares de soja - STS y no-STS y segundo factor: 5 períodos entre la aplicación y la siembra de soja - 0, 15, 30, 45 y 60 días). A los 7, 14, 21 y 28 días después de la siembra se realizó una evaluación de emergencia de las plántulas de soja, a los 28 días, se evaluó la altura y la masa seca de la parte aérea. Los promedios de altura para el cultivar STS fueron más altos que los valores del cultivar no-STS. La masa seca promedio de las plantas de soja fue mayor en el cultivar STS a los 0, 15 y 30 días entre la aplicación y la siembra. No se observaron diferencias entre los cultivares por los periodos de 45 y 60 días, para el promedio de masa seca. El cultivar de soja BMX Garra RR2/STS fue potencialmente tolerante para la aplicación previa a la siembra del metsulfurón. El cultivar de M 6410 IPRO (no-STS) tuvo su desarrollo inicial afectado por la aplicación de metsulfurón en preemergencia; sin embargo, la aplicación de metsulfurón de 60 días fue más segura y, por lo tanto, se recomienda realizar la aplicación de herbicida en ese intervalo de tiempo.

ABSTRACT Metsulfuron is widely used for weed management; however, the residual effect on STS soybean cultivars is unknown. The objective of this work was to evaluate the residual effect of the herbicide metsulfuron on the BMX Garra RR2/STS and M 6410 IPRO (non-STS) soybean cultivars. The herbicide metsulfuron was applied at a rate of 2.4 g a.i. ha-1, in pre-planting of soybean plants. The design was completely randomized in a 2×5 factorial scheme with four replications (first factor: two soybean cultivars - STS and no-STS; second factor: five periods between metsulfuron application and soybean sowing - 0, 15, 30, 45, and 60 days). At 7, 14, 21, and 28 days after sowing (DAS), an emergency evaluation of the soybean seedlings was performed; at 28 DAS, height and dry mass of the shoot were evaluated. The height averages for the STS cultivar were higher than the values of the no-STS cultivar. The average dry mass of soybean plants was higher in the STS cultivar at 0, 15, and 30 days between application and sowing. No differences were observed between the cultivars for the periods of 45 and 60 days, for average dry mass. The BMX soybean cultivar Garra RR2/STS was potentially tolerant for the pre-sowing application of the herbicide metsulfuron. The cultivar of M 6410 IPRO (non-STS) was affected in its initial development by the metsulfuron application during the pre-emergence stage; however, the 60-day metsulfuron application was safer, and therefore, it is recommended to perform the herbicide application in that interval.

RESUMO: Há poucas informações sobre a eficácia e seletividade de sulfonilureias, isoladas e associadas ao glifosato, na soja tolerante ao glifosato e às sulfonilureias. Assim, o presente estudo teve como objetivo avaliar a eficácia no controle de plantas daninhas e seletividade de sulfonilureias, isoladas e em associação com o glifosato, em pós-emergência (V4) de soja RR2/STS. Os experimentos foram conduzidos em áreas localizadas nos municípios de Piracicaba, São Paulo (SP), Brasil (experimento I) e Palotina, Paraná (PR), Brasil (experimento II). Os tratamentos foram compostos pela aplicação dos herbicidas sulfometurom, clorimurom, halossulfurom, etoxissulfurom e glifosato, isolados e em associação, no cultivar BMX Garra RR2/STS. O experimento I foi realizado com o foco principal na avaliação da eficácia no controle de plantas daninhas; ao passo que o experimento II se concentrou principalmente na avaliação da seletividade dos herbicidas. O delineamento experimental foi o de blocos casualizados, com quatro repetições. Foram avaliados sintomas de injúria, controle de plantas daninhas e variáveis relacionadas ao desempenho agronômico. Os dados foram submetidos à análise de variância, e as médias dos tratamentos foram comparadas pelo teste de Tukey. Sulfonilureias associadas ao glifosato foram eficazes no controle de plantas daninhas e seletivas para o cultivar de soja BMX Garra RR2/STS. A associação sulfometurom + clorimurom + glifosato apresentou potencial fitotóxico para o cultivar BMX Garra RR2/STS.

ABSTRACT: There is little information on the efficacy and selectivity of sulfonylureas, isolated and in association with glyphosate, in glyphosate and sulfonylurea-tolerant soybeans. Thus, the present study aims to evaluate the efficacy of weed control and selectivity of sulfonylureas, isolated and in association with glyphosate, at post-emergence (V4) of RR2/STS soybean. The experiments were conducted in the in areas located in Piracicaba City, São Paulo State (SP), Brazil (experiment I) and Palotina City, Paraná State (PR), Brazil (experiment II). Treatments were composed of application of the herbicides sulfometuron, chlorimuron, halosulfuron, ethoxysulfuron and glyphosate, isolated and in association, in the BMX Garra RR2/STS cultivar. Experiment I was conducted focusing on the evaluation of the efficacy of weed control; whereas experiment II focused mainly on the evaluation of herbicide selectivity. The experimental design was the randomized complete block, with four replications. Crop injury, weed control, and variables related to agronomic performance were evaluated. Data were submitted to analysis of variance, and the means of the treatments were compared with the Tukey test. Sulfonylureas in association with glyphosate were effective in weed control and selective for the BMX Garra RR2/STS soybean cultivar. The sulfometuron + chlorimuron + glyphosate association presented phytotoxic potential for the BMX Garra RR2/STS cultivar.

RESUMO O manejo químico é o mais adotado para o controle de plantas daninhas na cultura da cana-de-açúcar. Entre as espécies de difícil controle está a tiririca (Cyperus rotundus L.). Os herbicidas utilizados precisam ser absorvidos e transportados para a cadeia de tubérculos em quantidades suficientes para serem eficazes. Assim, objetivou-se com este estudo avaliar a eficácia dos herbicidas sulfentrazona, diclosulam, imazapique, imazapir, halossulfurom, etoxissulfurom, metano arseniato ácido monossodico (MSMA) e ácido diclorofenoxiacético (2,4-D) no controle de C. rotundus e na redução da viabilidade de seus tubérculos. O experimento foi realizado em casa de vegetação, em delineamento inteiramente randomizado, com nove tratamentos e quatro repetições. Os herbicidas sulfentrazone (800 g ingrediente ativo – i.a.·ha-1), diclosulam (193,17 g i.a.·ha-1), imazapique (133 g i.a.·ha-1) e imazapir (500 g equivalente – e.a.·ha-1) foram aplicados cinco dias após o plantio dos tubérculos em pré-emergência, enquanto que o halossulfurom (112,5 g i.a.·ha-1), etoxissulfurom (135 g i.a.·ha-1), MSMA (1.975 g i.a.·ha-1) e 2,4-D (1.340 g e.a.·ha-1) foram aplicados em pós-emergência (4 a 5 folhas). Foram feitas avaliações visuais de controle, massa seca da parte aérea, número de tubérculos e bulbos, peso de tubérculos + bulbos, número de manifestações epígeas e viabilidade de tubérculos. Aos 90 dias após a aplicação (DAA) os herbicidas diclosulam, halossulfurom e etoxissulfurom propiciaram 100% de controle da parte aérea. Todos os herbicidas reduziram o número de bulbos, peso de tubérculos + bulbos e massa seca da parte aérea. Sulfentrazona, imazapic, halossulfurom, etoxissulfurom e MSMA foram os herbicidas que mais reduziram a viabilidade dos tubérculos.

ABSTRACT Chemical management is the most widely adopted technique to control weeds in sugarcane crops. Purple nutsedge (Cyperus rotundus L.) is among the most difficult species to control. Herbicides need to be absorbed and translocated in a sufficient amount for the tuber chain to be effective. Thus, this study aimed to evaluate the effectiveness of the herbicides sulfentrazone, diclosulam, imazapic, imazapyr, halosulfuron, ethoxysulfuron, monosodium methyl arsenate (MSMA), and 2,4-dichlorophenoxyacetic acid (2,4-D) in controlling C. rotundus and reducing the viability of its tubers. The experiment was carried out in a greenhouse in a completely randomized design, with nine treatments and four replications. The herbicides sulfentrazone (800 g active ingredient – ai·ha?1), diclosulam (193.17 g ai·ha?1), imazapic (133 g ai·ha?1), and imazapyr (500 g acid equivalent – ae·ha?1) were applied in preemergence at five days after planting the tubers, while halosulfuron (112.5 g ai·ha?1), ethoxysulfuron (135 g ai·ha?1), MSMA (1,975 g ai·ha?1), and 2,4-D (1,340 g ae·ha?1) were applied in postemergence (4 to 5 leaves). The parameters visual control, shoot dry matter, number of tubers and bulbs, weight of tubers + bulbs, number of epigeal manifestations, and tuber viability were analyzed. The herbicides diclosulam, halosulfuron, and ethoxysulfuron provided 100% control of the shoot at 90 days after application (DAA). All herbicides reduced the number of bulbs, weight of tubers + bulbs, and shoot dry matter. The herbicides sulfentrazone, imazapic, halosulfuron, ethoxysulfuron, and MSMA provided the highest reduction in tuber viability.

ABSTRACT The aim was to evaluate the selectivity and weed control of herbicides atrazine, nicosulfuron, mesotrione and tembotrione, applied alone and associated, in post-emergence of maize. Were carried out two experiments, one in the field in a randomized complete block design with four replications and eleven treatments, the second in greenhouse in a completely randomized design, with four replications and ten treatments. The treatments were composed of isolated and associated herbicides. Treatments were applied V4 stage of plants. For first experiment, crop injury and control evaluations were performed, as well as variables related to agronomic performance (plant height, ear insertion height, prolificacy index, yield and mass of 1,000 grains) and mass of weeds. For second experiment, evaluations of crop injury, height, diameter and dry mass of plants were performed. The lower yield for experiment one was verified in the treatment where only mesotrione was applied, which was attributed to the lower control of monocotyledons weeds. Crop injury were observed at 21 DAA in both experiments, but not exceeding 7.5%. All treatments were considered selective to maize. The herbicides atrazine, nicosulfuron, mesotrione and tembotrione, at associations, were effective in the weed control, except the association atrazine + mesotrione.

Resumen Las malezas compiten con las plantas cultivadas por el agua, la luz, los nutrientes y el espacio. En la caña de azúcar, la siembra con plántulas pre brotadas de caña de azúcar (PPB) puede significar un cambio en la interferencia y el manejo de las malezas. El objetivo de este trabajo fue evaluar la interferencia de Cyperus rotundus L. en plántulas pre-brotadas (PPB) de caña de azúcar. Se realizaron dos experimentos en invernadero, en diseño completamente al azar, uno con el cultivar RB985476, con siete densidades de C. rotundus (0, 17, 35, 70, 140, 280 y 560 plantas m-2). El segundo con el cultivar IACSP95-5000, con cuatro densidades de C. rotundus (0, 70, 140 y 280 plantas m-2). Para la maleza se adoptó un arreglo factorial de 2x6 para el experimento con RB985476 y 2x3 para IACSP95-5000, con el primer factor siendo la ausencia y presencia de caña de azúcar y el segundo factor las densidades de la especie. Se realizaron evaluaciones de altura, diámetro, número de perfiles y hojas, área foliar y masa seca de la parte aérea. Las PPB tuvieron reducción en altura, número de hojas y área foliar del perfil principal a los 60 días después del plantío en la RB985476. Para la variedad IACSP95-5000, no hubo reducción en las variables analizadas. La masa seca media por planta de C. rotundus se redujo con el aumento de la densidad de la especie en ausencia de PPB.

Abstract Weeds compete with plants for water, light, nutrients and space. In sugarcane, planting pre-sprouted sugarcane seedlings (PSS) may mean a change in weed interference and management. The aim of this study was to generate information on the interference of Cyperus rotundus L. in PSS. Two experiments were carried out in a completely randomized design, one with cultivar RB985476, with seven densities of C. rotundus (0, 17, 35, 70, 140, 280 and 560 plants m-2), and the second with cultivar IACSP95-5000, with four densities of C. rotundus (0, 70, 140 and 280 plants m-2). For this weed, a 2x6 factorial design was used for the experiment with RB985476 and a 2x3 design was used for IACSP95-5000, the first factor being absence and presence of the crop, and the second factor the densities of the species. Biometric evaluations of height, diameter, number of tillers and leaves, leaf area and dry mass were carried out. The PSS had a reduction in height, number of leaves and leaf area in the main till at 60 d after planting (DAP) in RB985476. For the IACSP95-5000 cultivar, there was no reduction in the analyzed variables. The average dry mass per plant of C. rotundus decreased as the density of the species increased in the absence of PSS.

RESUMO: A “segunda geração” de soja tolerante ao glifosato (soja RR®2) foi desenvolvida por meio de uma diferente inserção do gene EPSPs insensível ao referido herbicida. Informações sobre a seletividade de glifosato, isolado ou em associação, são faltantes em soja RR2. Este estudo avaliou os efeitos do glifosato, isolado ou em associações, aplicado em pós-emergência (V4), no desempenho agronômico e na qualidade de sementes do cultivar de soja NS 6700 IPRO (RR2). Adotou-se o delineamento experimental de blocos ao acaso com quatro repetições e sete tratamentos, realizados no campo em duas safras. Os tratamentos consistiram no herbicida glifosato, isolado ou em associação com clethodim, cloransulam, chlorimuron, lactofen e fluazifop, além da testemunha sem aplicação. Foi realizada a avaliação dos sintomas de injúria e índice SPAD (Soil and Plant Analyzer Development), bem como de variáveis relacionadas ao desempenho agronômico (altura, número de vagens por planta, produtividade e massa de 1.000 sementes) e à qualidade das sementes (vigor, germinação, plântulas anormais e sementes mortas). Experimento complementar foi realizado com o mesmo cultivar e tratamentos em casa de vegetação em delineamento inteiramente casualizado com quatro repetições. Os herbicidas não afetaram o desempenho agronômico e a qualidade de sementes da soja RR2. Assim, o cultivar NS 6700 IPRO (RR2) foi tolerante ao glifosato, isolado ou em associação com outros herbicidas aplicados em pós-emergência (V4).

ABSTRACT: The “second generation” of glyphosate-tolerant soybean (RR®2 soybean) was developed through a different technique of insertion of the glyphosate-insensitive EPSPs gene. Information on the selectivity of glyphosate, alone or in combination, in RR2 soybean is lacking. This study evaluated the effects of glyphosate, isolated or in associations, applied at post-emergence (V4), at agronomic performance and seed quality of soybean cultivar NS 6700 IPRO (RR2). The experimental design was randomized block with four replications and seven treatments, conducted in the field for two growing seasons. The treatments consisted of glyphosate herbicide, alone or in combination with clethodim, cloransulam, chlorimuron, lactofen and fluazifop, besides the control without application. Analysis was performed for crop injury, Soil and Plant Analyzer Development (SPAD) index, as well as variables related to agronomic performance (height, number of pods per plant, yield and 1,000-seed weight) and seed quality (vigor, germination, abnormal seedlings and dead seeds). An additional test was conducted with the same cultivar and treatments in a greenhouse in a completely randomized design with four replications. The herbicides did not affect agronomic performance and seed quality of RR2 soybean. Thus, the soybean cultivar NS 6700 IPRO (RR2) was tolerant to glyphosate, alone or combined with other herbicides applied in post-emergence (V4).

Objetivou-se com este trabalho estudar a inter-relação entre a cultura de milho e cultivares de Urochloa spp. em consórcio, assim como a interferência de plantas daninhas nesses sistemas. O ensaio foi aleatorizado em três blocos em esquema de parcelas subdivididas, sendo as parcelas constituídas por sete sistemas de produção (Urochloa brizantha cv. 'Marandu' e cv. 'Piatã' e U. decumbens cv. 'Basilisk' em cultivo solteiro e em consórcio com o milho e cultivo solteiro de milho) e as subparcelas pelo controle de plantas daninhas (com e sem capina manual). Verificou-se que o estabelecimento dos consórcios de milho com as cultivares de Urochloa spp. não afeta os componentes de rendimento de produção, altura e produtividade do milho, assim como não reduz a comunidade de plantas daninhas, mas interfere na densidade populacional e massa de matéria seca por planta e por área das cultivares de Urochloa spp. Houve níveis de interferência semelhantes das plantas daninhas entre os sistemas de produção sem capina, devido à similaridade entre suas comunidades de plantas daninhas, com predomínio de espécies consideradas altamente competitivas, como Panicum maximum, e à predominância de espécies como Richardia brasiliensis e Ageratum conyzoides, associadas ao controle com capina.

This research was carried out to study the interaction between the corn and Urochloa spp. cultivars in association, as well as the interference of weeds in this cropping system. A randomized experiment in three blocks with split-plots design was conducted. The plots consisted of seven cropping systems (Urochloa brizantha cv. 'Marandu' and cv. 'Piatã' and U. decumbens cv. 'Basilisk' a sole culture and in association with corn as well as the sole culture of corn) and the split-plots by weed control (with and without weeding). It was found that the establishment of corn-Urochloa spp. cultivars association does not affect yield components such as height and grain yield, nor reduces the weed community, but interferes in the density, mass of dry matter per plant and per area of Urochloa spp. cultivars. There were similar levels of interference of weeds between cropping systems without weeding due to the similarity between the weed communities, showing the predominance of species considered as highly competitive such as Panicum maximum and also due to the low infestation with predominance of species such as Richardia brasiliensis and Ageratum conyzoides, associated with weed control.

O objetivo deste trabalho foi avaliar os efeitos da cobertura morta e da vegetação intercalar composta por gramíneas e leguminosas perenes nas propriedades químicas do solo e no estado nutricional de plantas de laranjeira 'Pêra' (Citrus sinensis (L.) Osbeck) enxertada em limoeiro 'Cravo' (Citrus limonia Osbeck). Os tratamentos testados foram: T1, Brachiaria ruziziensis R. Germ. & Evrard na entrelinha sem cobertura morta na linha; T2, B. ruziziensis na entrelinha e cobertura morta na linha; T3, B. ruziziensis consorciada com amendoim forrageiro (Arachis pintoi Krap. & Greg) na entrelinha e cobertura morta na linha; T4, B. ruziziensis e estilosantes (Stylosanthes capitata, S. macrocephala e S. guianensis) na entrelinha e cobertura morta na linha; T5, capim-marmelada (Brachiaria plantaginea (Link) Hitch.) na entrelinha e cobertura morta na linha; T6, amendoim forrageiro na entrelinha e cobertura morta na linha; T7, estilosantes na entrelinha e cobertura morta na linha. A leguminosa estilosantes proporcionou aumento da concentração foliar de N em relação à vegetação intercalar composta por B. ruziziensis. A cobertura morta não reduziu a disponibilidade de N para as plantas cítricas. Verificou-se correlação entre a densidade do sistema radicular na camada superficial do solo com a concentração foliar de P e produção de frutos.

The objective of this work was to evaluate the effects of cover crops composed of grass and perennial leguminous in the orchard inter-rows and mulch on the rows, on soil chemical characteristics and nutritional status of Citrus sinensis (L.) Osbeck cv. Pêra sweet orange budded on 'Rangpur' lime (Citrus limonia Osbeck). The treatments were: T1, Cover crop of Brachiaria ruziziensis R. Germ. & Evrard, without mulch on the row; T2, B. ruziziensis and mulch on the row; T3, B. ruziziensis and Arachis pintoi and mulch on the row; T4, B. ruziziensis and stylosanthes and mulch on the row; T5, Brachiaria plantaginea and mulch on the row; T6, Arachis pintoi and mulch on the row; T7, stylosanthes and mulch on the row. Stylosanthes increased N leaf content compared to B. ruziziensis. Grass mulch had no significant effect on N leaf content. There was significant interaction between root density into superficial soil layer, P leaf content and yield.

Com o objetivo de verificar a resposta de diferentes espécies de plantas daninhas ao herbicida glyphosate, foi desenvolvido em câmara de crescimento um experimento inteiramente casualizado, com cinco repetições no Departamento de Produção Vegetal da ESALQ/USP. Para isso, foram estudadas seis espécies de plantas daninhas: Bidens pilosa L., Tridax procumbens L., Digitaria insularis (L). Fedde, Spermacoce latifolia Aubl., Ipomoea grandifolia L. e Commelina benghalensis L. Utilizou-se o herbicida glyphosate, inibidor da enzima EPSPs, com doses em escalas de 0,0; 11,3; 22,5; 45; 90; 180; 360; 720 e 1.440 g.ha-1 i.a. A elaboração das curvas dose-resposta foi feita pelo ajuste da equação dos dados coletados de biomassa verde utilizando o modelo log-logístico: Y = C+D-C / 1 + Exp{b[log(x)-log(RC50)]}, calculado por modelo estatístico não linear dos dados pelo programa estatístico SAS. Após a determinação das curvas dose-resposta nas espécies acima citadas concluiu-se que Bidens pilosa foi considerada a planta daninha mais suscetível ao herbicida glyphosate, pois apresentou menor RC50 (31,86 g.ha-1 i.a.). As espécies Tridax procumbens, Digitaria insularis, Spermacoce latifolia, Ipomoea grandifolia, Commelina benghalensis obtiveram RC50 de 58,40; 128,50; 250,44; 615,49 e >1.440 g.ha-1 i.a. respectivamente. Portanto, a quantidade necessária de herbicida para reduzir em 50% a biomassa verde foi de 1,83; 4,03; 7,86; 32 e >359,56 vezes maior em relação à Bidens pilosa respectivamente.

With the objective of veryfing the response of different doses in species of weeds by herbicide glyphosate, an experiment was conducted in growth chamber in a completetly randomized design with three repetitions, in the Department of Vegetable Production at ESALQ/USP. For that, were chosen six species of weeds: Bidens pilosa L., Tridax procumbens L., Digitaria insularis (L.) Feed, Spermacoce latifolia Aubl., Ipomoea grandifolia L. and Commelina benghalensis L. The herbicide glyphosate, inhibitor of the enzyme EPSPs, was used at rate 0.0; 11.3; 22.5; 45; 90; 180; 360; 720 and 1440 g.ha-1 a.i. Curves of dose-response were made by the adjustment of the equation of the collected data of green biomass using the log-logistic model: Y = C+D-C / 1 + Exp{b[log(x)-log(RC50)]}, calculated by the no linear statistical model through the SAS statistical program. After the determination of the dose-response curves for the species mentioned above the Bidens pilosa was considered the most susceptible weed to glyphosate, showing the houvest RC50 (31.86 g.ha-1 a.i.). The species Tridax procumbens, Digitaria insularis, Spermacoce latifolia, Ipomoea grandifolia and Commelina benghalensis obtained RC50 equal to 58.40; 128.50; 250.44; 615.49 and > 1440.00 g.ha-1 a.i., respectively, what means that the necessary amount of herbicide to reduce in 50% the green biomass was 1.83; 4.03; 7.86; 19.31 and >359.56 times higher in relation the Bidens pilosa.

O "banco" de sementes é um reservatório de sementes de plantas viáveis presentes na camada superficial de solo, que determina a composição de plantas daninhas emergidas na área; no entanto, a composição qualitativa e quantitativa do banco de sementes é determinada principalmente pelas práticas culturais empregadas na área. Sendo assim, foi avaliado o "banco" de sementes de plantas daninhas para determinar as possíveis influências dos diferentes sistemas de manejo utilizados na cultura dos citros. Os tratamentos consistiram da aplicação dos herbicidas diuron (2,0 kg ha-1), em pré-emergência, e glyphosate (1,08 kg ha-1), em pós-emergência, na linha de plantio, associados a cinco práticas de manejo na entrelinha da cultura: gradagem, roçada, dose reduzida de glyphosate, guandu (Cajanus cajan) e lab-lab (Dolichus lablab). Retiraram-se amostras de solo das entrelinhas e linhas de citros, nas profundidades de 0-10 cm e 10-20 cm, em épocas chuvosa e seca. As amostras foram colocadas em bandejas e levadas à casa-de-vegetação, para que as sementes presentes germinassem. Avaliou-se a emergência das plântulas aos 15, 30, 60 e 90 dias após implantação, por contagem e identificação de espécies. A utilização de grade e roçadeira proporcionaram maiores percentagens de número de plantas, enquanto que as leguminosas suprimiram a germinação das plantas daninhas.

The weed seed bank is a viable soil seed reservoir present in the top soil profile, which determines the emerged weed species composition in the area, however, the qualitative and quantitative composition of the weed soil seed bank is determined mainly by the cultural practices to which the area is submitted. Therefore the influence of different soil management systems used in a citrus orchard was evaluated in relation to the weed seed bank composition. The treatments consisted of pre-emergence application of diuron (2.0 kg ha-1) and post-emergence of glyphosate (1.08 kg ha-1) on the citrus rows associated with five weed inter-row management practices: disking, mowing, reduced rate of glyphosate, green manure (Cajanus cajan and Dolichus lablab). Soil samples were collected from the row and inter-row at depths of 0-10 cm and 10-20 cm, during the dry and wet seasons of the year. The samples were placed in trays under greenhouse conditions in order to count weed emergence four times. The inter-row mechanical treatments of disking and mowing caused higher weed population, while the legume green manure reduced the weed seed population significantly in the 0-10 cm layer.