Resumen El herbicida tembotrione tiene un buen control de malezas y puede ser una herramienta importante en el cultivo del sorgo. Sin embargo, este herbicida está registrado en Brasil solo para maíz. Este estudio tuvo como objetivo evaluar la selectividad de la tembotrione asociada a la atrazine en diferentes dosis y etapas de desarrollo del grano de sorgo. Se realizaron dos experimentos en Rio Verde-GO y Montividiu-GO, Brasil en 2018. Se adoptó un diseño de bloques al azar con cuatro repeticiones, en un factorial 3x2+1+1, con tres etapas de desarrollo (V3, V5 y V7), dos dosis de tembotrione (37,8 y 75,6 g ha-1) asociada al herbicida atrazine (1,000 g ha-1), un tratamiento adicional con solo atrazine en V3 más un testigo sin herbicida. Los resultados permitieron observar síntomas visibles de fitotoxicidad cuando se aplicó la asociación entre los herbicidas tembotrione y atrazine en la etapa V3 y V5. Los síntomas incluyeron reducciones en la altura de la planta y el diámetro del tallo del sorgo y reducciones en la longitud de la panícula con la aplicación en la etapa V5. La aplicación de tembotrione en asociación con atrazine en V3 y V5 resultó en una reducción de la acumulación de masa seca en la parte aérea de las plantas de sorgo, pero sin influencia en la masa de mil granos, independientemente de la etapa de aplicación. El herbicida tembotrione en dosis de 37,8 g ha-1 en asociación con atrazine en dosis de 1,000 g ha-1 fue selectivo para sorgo en grano cuando se aplicó en V7, sin causar reducción en el rendimiento de grano.

Abstract The herbicide tembotrione is effective against grassy weeds constituting an important tool in sorghum crops. However, in Brazil, this herbicide is only registered for corn. This study aimed to evaluate the selectiveness of tembotrione combined with atrazine at different doses and developmental stages of grain sorghum. Two experiments were conducted in Rio Verde and Montividiu, state of Goiás, Brazil, in 2018. A randomized block design with four replications, in a 3x2+1+1 factorial arrangement, tested three developmental stages (V3, V5 and V7), two doses of tembotrione (37.8 and 75.6 g ha-1) combined with the herbicide atrazine (1,000 g ha-1), an additional treatment only with atrazine at V3 and a control, free of herbicide. Evident phytotoxicity was observed with the combination of tembotrione and atrazine at V3 and V5 stages. Symptoms included reductions in plant height, sorghum stem diameter, panicle length, and cumulative dry mass of sorghum plant shoots. However, there was no influence on thousand grains mass, regardless of application stages. Tembotrione at 37.8 g ha-1 combined with atrazine at 1,000 g ha-1 was selective for grain sorghum when applied at V7, without affecting grain yield.

ABSTRACT The herbicide tembotrione may be seletivity to sorghum, which is of utmost importance in grain production systems. Thus, the present study aimed to evaluate the selectivity of tembotrione + atrazine combinations applied post-emergence at different phenological stages of grain sorghum. Four experiments were carried out in Rio Verde and Montividiu (state of Goiás) in succession to soybean cultivation in 2017 and 2018. The experiments were carried out in randomized block design with six replications, both in a (3x2) + 1 factorial arrangement. The first factor referred to three vegetative stages of application (V3, V5 and V7) associated with two doses of tembotrione (90 and 180 g ha-1) combined with atrazine (1,000 g ha-1)and and an additional treatment with no herbicide application. Tembotrione + atrazine applications at the V7 stage caused less damage to grain yield and dry mass accumulation in relation to V3 and V5. The dose of 90 g ha-1 tembotrione + atrazine combined with atrazine resulted in higher grain yields compared to 180 g ha-1, although still at lower levels compared to the treatment with no herbicides. Thus, herbicide tembotrione at doses of 90 and 180 g ha-1 combined with atrazine did not have selectivity for grain sorghum in applications at V3, V5 and V7 stages. systems Thus postemergence post emergence state Goiás 201 2018 replications 3x2 x (3x2 arrangement V (V3 (9 18 ha1 ha 1,000 1000 000 (1,00 ha1and haand 9 ha- ha1, 1, herbicides 20 3x (3x (V ( 1,00 100 00 (1,0 2 1,0 10 0 (1, (1

Resumen El mejoramiento genético de los cultivares de soja a lo largo de los años se ha centrado en aumentar la capacidad productiva y la tolerancia a algunos factores abióticos y bióticos. Sin embargo, durante la transferencia de genes de interés, algunos genes responsables de una menor tolerancia a los herbicidas pueden integrarse en el genoma del nuevo cultivar. El objetivo de este estudio fue evaluar la selectividad de las asociaciones de herbicidas apli cadas en la post-emergencia de tres cultivares de soja. El diseño experimental utilizado fue un bloque completamente al azar, con cuatro repeticiones. Los cultivares seleccionados fueron M7110 IPRO®, Foco IPRO® y Bônus IPRO®. Los herbicidas y las respectivas dosis (g a.i. ha-1) utilizados fueron: glyphosate (1176), glyphosate + bentazon (1176 + 600), glyphosate + fomesafen (1176 + 175), glyphosate + lactofen (1176 + 120), glyphosate + imazethapyr (1176 + 100), glyphosate + chlorimuron (1176 + 10), glyphosate + cloransulam (1176 + 39,5), y un control sin aplicación de herbicida. Se hizo una nota visual de intoxicación para cada tratamiento. Los componentes de crecimiento y rendimiento evaluados fueron: altura, rodal, peso de cien granos y rendimiento. La aplicación de herbicidas en post-emergencia no alteró la masa vegetal de los cultivares de soja. Además, estos herbicidas no redujeron el rendimiento de los cultivares M7110 IPRO® y Foco IPRO®. Tanto el glifosato aislado como mezclado con lactofen o imazethapyr redujeron el rendimiento del cultivar Bônus IPRO®.

Abstract The genetic improvement of soybean cultivars over the years has focused on increasing the yield potential and tolerance to some abiotic and biotic factors. However, during the transfer of genes of interest, some genes responsible for a lower tolerance to herbicides can be integrated into the genome of the new cultivar. Thus, the objective of this study was to evaluate the selectivity of herbicide associations applied in the postemergence period of three soybean cultivars. The experiment was conducted in a randomized completely block design, with four replications. The selected cultivars were M7110 IPRO®, Foco IPRO®, and Bônus IPRO®. The herbicides and the respective doses (g a.i. ha-1) used were glyphosate (1176), glyphosate + bentazon (1176 + 600), glyphosate + fomesafen (1176 + 175), glyphosate + lactofen (1176 + 120), glyphosate + imazethapyr (1176 + 100), glyphosate + chlorimuron (1176 + 10), glyphosate + cloransulam (1176 + 39.5), and a control without herbicide application. The visual note of intoxication was evaluated for each treatment. The components of growth and yield evaluated were height, stand, weight of one hundred grains, and yield. The application of postherbicide herbicides did not alter the plant stands of soybean cultivars. Additionally, these herbicides did not reduce the yield of the M7110 IPRO® and Foco IPRO® cultivars. Glyphosate isolated and in association with lactofen or imazethapyr reduced the grain yield of the Bônus IPRO® cultivar.

RESUMEN El espaciamiento entre hileras comúnmente utilizado en el cultivo de yuca en Brasil, especialmente en la región de Agreste de Alagoas, varía de 100 a 120cm. Sin embargo, la reducción del espacio entre hileras puede promover ganancias agronómicas y ambientales en los sistemas de cultivo con yuca. Por lo tanto, el objetivo de este trabajo fue evaluar el comportamiento de dos variedades de yuca cultivadas con espaciamiento reducido entre hileras. Se realizaron dos experimentos en el campo, uno en el 2015/16 y otro en el 2017/18. El diseño experimental utilizado en ambos experimentos fue el de Parcelas Divididas con cuatro repeticiones. Se evaluaron cuatro espaciamientos entre filas en la parcela principal: 60, 80, 100 y 120cm, con plantas espaciadas 60cm dentro de las hileras, dando poblaciones de 27,778, 20,833, 16,667 y 13,889 plantas por hectárea, respectivamente. En las subparcelas se evaluaron dos variedades de yuca: Caravela y Pretinha. Un aumento en el espaciamiento entre hileras promovió una reducción lineal en la masa verde del tallo de la yuca. La altura de la planta, la masa verde de la hoja, el diámetro del tallo principal, el rendimiento de la raíz, la longitud de la raíz tuberosa, el diámetro de la raíz tuberosa, el porcentaje de harina, el rendimiento de la harina y el contenido de almidón no se vieron afectados por los cambios en el espaciamiento entre hileras. La variedad Pretinha fue superior a Caravela en las siguientes características evaluadas: masa verde del tallo, diámetro de raíces tuberosas, rendimiento de raíces, altura de planta y rendimiento de harina. Los resultados indican la posibilidad de alterar el espaciamiento entre hileras en la yuca para ayudar en el manejo cultural, sin afectar el rendimiento del cultivo.

ABSTRACT The interrow spacing commonly used in cassava cultivation in Brazil, especially in the Agreste region of Alagoas, ranges from 100 to 120cm. However, the reduction in row spacing can provide agronomic and environmental benefits in cassava cropping systems. Thus, this work aimed to evaluate the performance of two cassava varieties cultivated with reduced interrow spacing. Two experiments were conducted in the field, one in 2015/16 and another in 2017/18. A Split Plot design with four replications was used in both experiments. Four interrow spacing were evaluated in the main plot: 60, 80, 100 and 120cm, with plants spaced 60cm apart within rows, giving populations of 27,778, 20,833, 16,667 and 13,889 plants per hectare, respectively. In the subplots, two cassava varieties were evaluated: Caravela and Pretinha. An increase in interrow spacing promoted a linear reduction in the stem green mass of cassava. Plant height, leaf green mass, main stem diameter, root yield, tuberous root length, tuberous root diameter, flour percentage, flour yield, and starch content were not influenced by changes in interrow spacing. The Pretinha variety was superior to Caravela in the following evaluated traits: stem green mass, the diameter of tuberous roots, root yield, plant height, and flour yield. The results indicate the possibility of altering the interrow spacing in cassava to assist in the cultural management, without impacting crop yield.

ABSTRACT. The succession of soybean/maize has been largely adopted. Storm damage and crop problems can lead to grain loss, generating maize ear fragments or even whole ears that remain in the soil and still display germination viability, resulting in the occurrence of volunteer plants. In this context, the present study aimed to evaluate the interference of voluntary maize plants on soybean and investigate the susceptibility of maize hybrids to pre-emergence herbicides. In the first step, an experiment was performed evaluating the influence of voluntary maize plant density and spatial distribution on soybean. The experiment was performed in a randomized completely block design (RCBD) with four replications, with treatments disposed in factorial arrangement (2 x 4) + 1. The first factor corresponded to the spatial distribution of maize plants: row or in between soybean rows; while the second factor adopted four infestation densities of maize plants m-2: 4, 8, 12, and 16. The additional treatment consisted of a control without maize plants. For the second step, an experiment was conducted in two locations aiming to determine the efficacy of pre-emergence herbicides in the control of voluntary maize. Both experiments were installed in RCBD in a split-plot scheme with four replications. Fomesafen, lactofen, sulfentrazone, chlorimuron-ethyl, diclosulam, flumetsulam, imazethapyr, clomazone, metribuzin, [sulfentrazone + diuron], [imazethapyr + flumioxazin], and a control without herbicide application were evaluated in the main plot. In each subplot, the maize hybrids DKB310 PRO3™ and DKB390 PRO3™ were evaluated. No influence on the position of voluntary maize on the soybean yield was observed. The presence of the maize population led to a progressive decrease in soybean yield, ranging up to 86%, at 16 plants m-2. DKB390 displayed a stand reduction of 82.88% after the use of diclosulam. Diclosulam led to better results regarding maize plant decreases for both hybrids.

ABSTRACT Weed management consists of a fundamental practice in cassava, with mechanical and chemical control widely used. The objective of this work was to evaluate the efficacy of pre-emergence herbicides, as well as to determine the interaction of these with weeding complementation in the weed management in cassava. Two experiments were conducted in Junqueiro (Alagoas). In 2015/16, the experimental design was based on randomized blocks, with treatments distributed in a split-split-plot scheme, with four replications. In the main plot, four pre-emergence associations of clomazone + flumioxazin in different doses were evaluated, in addition to a control without herbicide. In the subplots, the Caravela and Pretinha cassava cultivars were evaluated, while in the sub-subplots the control complementation was evaluated using or not the manual weeding. In the 2016/17, the plot design and layout remained the same as for 2015/16, except for the composition of the herbicide treatments, since the standardization of clomazone dose has been chosen, varying only the doses of flumioxazin. The association of clomazone and flumioxazin has shown efficacy in weed control, with a greater residual as higher doses are used. This association provided higher shoot and root yield. Weeding complementation along the cassava cycle can increase its yield.

RESUMO A interferência de plantas daninhas prejudica o desenvolvimento da mandioca, sendo fundamental a adoção de medidas de controle. A utilização de herbicidas em pré-emergência é uma das alternativas de controle de plantas daninhas, visto que a mandioca apresenta boa tolerância a esta modalidade de aplicação. Mesmo herbicidas registrados podem apresentar seletividade diferencial em função da variedade de mandioca. Neste contexto, objetivou-se avaliar a eficácia no controle de plantas daninhas e a seletividade de associações herbicidas aplicados em pré-emergência de variedades de mandioca. Dois experimentos foram instalados a campo no delineamento de blocos completos ao acaso, em esquema de parcelas subdivididas, com quatro repetições. No experimento de eficácia, foram avaliadas na parcela principal seis associações herbicidas compostas pela aplicação de clomazone + ametryn, clomazone + metribuzin, clomazone + flumioxazin, isoxaflutole + ametryn, isoxaflutole + metribuzin, isoxaflutole + flumioxazin, além de testemunha sem capina e outra capinada. Nas subparcelas foram plantadas as variedades Caravela e Pretinha. Para o experimento de seletividade não houve a inclusão da testemunha sem aplicação e sem capina. As associações herbicidas contendo clomazone apresentaram maior período residual de controle de plantas daninhas, além de maior eficácia sobre trapoeraba. Entre os herbicidas associados ao clomazone ou isoxaflutole, o metribuzin foi o que apresentou menor eficácia. A variedade Pretinha apresenta maior tolerância a interferência das plantas daninhas. Todas as associações herbicidas aplicadas em pré-emergência da mandioca apresentaram seletividade para as variedades Caravela e Pretinha.

ABSTRACT The interference imposed by weeds can cause damages to cassava development. Thus, adopting control measures is fundamental. The use of pre-emergence herbicides is one of the control alternatives, since cassava presents a good tolerance to herbicides applied in this modality. However, herbicides may present differential selectivity due to the variety of cassava that is planted. The objective of this study was to evaluate both weed control effectiveness and selectivity of different herbicide combinations applied at pre-emergence of two cassava varieties. Two experiments were established in the field using a randomized complete block design, in a split plot scheme, with four replications. In the efficacy experiment, application of six combinations of herbicides, including clomazone + ametryn, clomazone + metribuzin, clomazone + flumioxazin, isoxaflutole + ametryn, isoxaflutole + metribuzin, isoxaflutole + flumioxazin were evaluated in the main plot. In addition, a non-treated control and a weeded control were evaluated. In the subplots, the Caravela and Pretinha varieties were planted. For the selectivity experiment, a non-treated control was not included. The combinations containing clomazone presented a longer residual period of weed control as well as a better control of benghal dayflower. Metribuzin exhibited lower efficacy than other herbicide combinations containing clomazone or isoxaflutole. The Pretinha variety showed greater tolerance to weed interference. Every herbicide combination that was applied in cassava pre-emergence presented selectivity for both Caravela and Pretinha varieties.

RESUMO. A adoção da tecnologia Roundup Ready® e o cultivo de segunda safra alteraram os métodos de controle químico e o manejo das plantas daninhas na região sudoeste do Estado de Goiás, Brasil. Tendo em vista estas alterações, este estudo teve o objetivo de realizar um levantamento fitossociológico em áreas de soja resistente ao glyphosate e soja convencional na safra principal e sorgo, milho, milheto ou pousio em sucessão na segunda safra. Foi constituída uma matriz multivariada da composição florística e calculado o valor indicador do número de indivíduos e biomassa seca das espécies. Com base no número de indivíduos as espécies Chamaesyce hirta, Bidens subalternans e Cissampelos ovolifolia foram típicas de áreas de cultivo com soja resistente ao glyphosate, enquanto que Euphorbia heterophyla apresentou valor indicador para áreas de cultivo de soja convencional. Na safrinha, os valores indicadores significativos foram observados para: Crotalaria spectabilis, nas áreas de milho; Cenchrus echinatus no sorgo; e Commelina benghalensis, Sida glaziovii, Ipomoea grandifolia, Sida rhombifolia e Ipomoea cordifolia, nas áreas com milheto. A espécie Conyza bonariensis foi típica do período que antecede a aplicação de herbicidas em pós-emergência na safra. A soja voluntária apresentou-se como típica para o período que antecede a aplicação de herbicidas em pós-emergência na safrinha. Foram registradas plantas daninhas de difícil controle, tolerantes e resistentes às aplicações de herbicidas nas áreas estudadas.

ABSTRACT. Roundup Ready® technology adoption and the cultivation of a second crop have changed chemical control methods and weed management in the southwest region of Goiás State, Brazil. Considering these changes, this study aimed to perform a phytosociological survey in areas with glyphosate resistant soybeans and conventional soybeans as the main harvest and sorghum, maize, millet or fallow in succession as the second harvest. A multivariate matrix of the floristic composition was constructed, and the indicator values of the individual number and dry biomass of species were measured. Based on the number of individuals, the species Chamaesyce hirta, Bidens subalternans, and Cissampelos ovolifolia were typical of areas cultivated with glyphosate-resistant soybean, while Euphorbia heterophyla presented indicator values of areas with conventional soybean cultivation. During the second harvest period, significant indicator values were observed for Crotalaria spectabilis in maize areas, Cenchrus echinatus in sorghum, and Commelina benghalensis, Sida glaziovii, Ipomoea grandifolia, Sida rhombifolia, and Ipomoea cordifolia in areas with millet. The species Conyza bonariensis was typical in the period before the herbicide application at post-emergence in harvest. Volunteer soybean presented as typical for the period before the herbicide application at post-emergence in the second harvest. Weeds that were difficult to control or were tolerant and resistant to the herbicide applications were recorded in the areas studied.

A integração lavoura-pecuária (ILP) tem demonstrado benefícios tanto para a produção de grãos, quanto para a pecuária. O cultivo de espécies forrageiras entre duas safras de soja é uma forma importante de ILP, no Brasil. Este trabalho objetivou avaliar a produtividade de cultivares de soja resistentes ao glifosato, cultivadas em integração com espécies gramíneas do gênero Urochloa, em diferentes formas de manejo do capim. Foram conduzidos seis experimentos, constituídos pela combinação de três cultivares de soja (BRS 295 RR, BRS 316 RR e BRS 294 RR) e duas espécies de gramíneas forrageiras (Urochloa ruziziensis e Urochloa brizantha). Foram avaliados quatro tratamentos (soja em cultivo solteiro; forrageira em cultivo solteiro; cultivo integrado de soja e uma espécie forrageira, com aplicação de glifosato, para reduzir o crescimento das gramíneas; e cultivo integrado de soja e uma espécie forrageira, sem supressão do crescimento), em delineamento experimental inteiramente casualizado, com quatro repetições. Em cada experimento, foi utilizada somente uma cultivar de soja e uma espécie forrageira. As gramíneas foram semeadas nas entrelinhas da soja, aos 27 dias após a semeadura (DAS), enquanto a aplicação de glifosato, no tratamento com supressão das forrageiras, foi realizada aos 84 DAS da soja ou 57 DAS das forrageiras. A produtividade das três cultivares não foi significativamente afetada pela interferência das gramíneas, e a produção de massa seca da parte aérea, para as gramíneas cultivadas em integração, foi alta, embora com valores inferiores aos obtidos sem a interferência imposta pela soja.

The integrated crop-livestock system is a key strategy for both grain and livestock production. The cultivation of grass species in between two soybean cropping seasons has been an important component of this system, in Brazil. Thus, this study aimed to evaluate the yield of glyphosate-resistant soybean cultivars intercropped with Urochloa species, under different forage management systems. A total of six experiments, consisting of three soybean cultivars (BRS 295 RR, BRS 316 RR, and BRS 294 RR) and two grass species (Urochloa ruziziensis and Urochloa brizantha), were established. For each experiment, four treatments (soybean only; grass only; soybean intercropped with a grass species, with the application of glyphosate to decrease the growth of grass; and soybean intercropped with a grass species, without growth suppression) were evaluated in a completely randomized experimental design, with four replications. For each experiment, only one soybean cultivar and one grass species were used. The grasses were sown in the soybean inter-rows at 27 days after sowing (DAS), while the glyphosate application to the treatment with grass suppression was performed at 84 DAS for the soybean or 57 DAS for the grasses. The yields of the three soybean cultivars were not significantly affected by either grass species, even though the shoot dry-matter yields for both of the intercropped grass species were high, though lower than the values obtained without the interference imposed by soybean.

Dentre as novas tecnologias, a fitorremediação é opção para a descontaminação de áreas que receberam intensas aplicações de herbicidas. Este trabalho foi desenvolvido com o objetivo de selecionar espécies com potencial para a fitorremediação de solos contaminados com o herbicida sulfentrazone. As espécies testadas foram: Calopogonium mucunoides, híbrido de sorgo (Sorghum bicolor x Sorghum sudanense), Crotalaria breviflora, Crotalaria juncea, Canavalia ensiformis, Dolichos lablab, Stizolobium deeringianum e Stizolobium aterrimum, cultivadas em cinco doses do sulfentrazone (0, 200, 400, 800 e 1.600 g ha-1). O experimento foi instalado em casa de vegetação, utilizando-se vasos com capacidade para 6 L, preenchidos com amostras de solo coletadas na profundidade de 0-20 cm. Foram avaliadas a fitotoxicidade do herbicida, a altura de plantas e a massa de matéria seca da parte aérea e de raízes. As espécies que manifestaram os menores sintomas de fitotoxicidade e os maiores índices de altura e matéria fresca e seca foram C. juncea, C. ensiformis e D. lablab, sendo selecionadas como tolerantes ao herbicida sulfentrazone e com potencial para fitorremediação.

Among the new technologies, phytoremediation is considered as an option for the decontamination of areas that thave undergone intense herbicide applications. This work aimed to select species with potential to the phytoremediation of soils contaminated with the herbicide sulfentrazone. The tested species were Calopogonium mucunoides, hybrid Sorghum (Sorghum bicolor x Sorghum sudanense), Crotalaria breviflora, Crotalaria juncea, Canavalia ensiformis, Dolichos lablab, Stizolobium deeringianum e Stizolobium aterrimum. The experiment was conducted in a greenhouse, using 6 dm³ vases filled with soil samples collected at a depth of 20 cm. The experimental design was the randomized blocks in a factorial scheme of 8 x 5, with four repetitions, which were composed by the eight plant species, and five doses of sulfentrazone (0, 200, 400, 800 and 1,600g ha-1). We evaluated the phytotoxicity of the herbicide, plant height and dry weight of shoots and roots. The species showing the least symptoms of phytotoxicity and the highest rates of height and fresh and dry biomass were C. juncea, C. ensiformis and D. lablab, which were selected as tolerant to the herbicide sulfentrazone and with potential for phytoremediation.

Resíduos de sulfentrazone podem permanecer no solo por cerca de dois anos, oferecendo risco de contaminação a lençóis freáticos e impossibilitando o cultivo de espécies susceptíveis. Diante disto, a fitorremediação pode representar uma opção para a descontaminação de áreas que sofreram com intensas aplicações deste herbicida. O presente trabalho avaliou o potencial remediador das espécies Crotalaria juncea, Canavalia ensiformis, Cajanus cajan e Cajanus cajan (anão), com relação ao herbicida sulfentrazone, utilizando-se o milheto (Pennisetum glaucum) como planta bioindicadora. O experimento foi instalado em casa-de-vegetação e os tratamentos compostos pela combinação entre as quatro espécies citadas, além da testemunha, e quatro doses de sulfentrazone (0 g i.a. ha-1, 200 g i.a. ha-1, 400 g i.a. ha-1 e 800 g i.a. ha-1). Foram avaliadas a altura de plantas, fitotoxicidade ao sulfentrazone e biomassa fresca e seca da parte aérea. Quando P. glaucum foi cultivado após C. juncea, apresentou maior ganho em biomassa e maior altura, e os sintomas de fitotoxicidade foram menos acentuados. C. juncea apresentou a maior capacidade de fitorremediar solos contaminados com sulfentrazone.

Residual sulfentrazone may remain in the soil for around two years, being a source of groundwater contamination and preventing the growth of susceptible plants. So, phytoremediation may represent an option for decontaminating areas which were highly affected by applications of this herbicide. This study aimed at evaluating the potential of Crotalaria juncea, Canavalia ensiformis, Cajanus cajan and Cajanus cajan (dwarf) for remediation of soil contaminated with sulfentrazone, using millet (Pennisetum glaucum) as a bioindicator plant. The experiment was installed in a greenhouse and treatments consisted of the four species already mentioned, plus a control, and four sulfentrazone doses (0 g a.i. ha-1, 200 g a.i. ha-1, 400 g a.i. ha-1 and 800 g a.i. ha-1). Plants height, phytotoxicity to sulfentrazone and fresh and dry matter were evaluated. When P. glaucum was grown after C. juncea, the fresh and dry matter, as well as plant height, were higher, while the phytotoxicity symptoms were less evident. C. juncea showed the best results for phytoremediation of soils contaminated with sulfentrazone.

O girassol é uma oleaginosa de destaque entre as culturas utilizadas em sucessão à soja na região dos cerrados. No entanto, poucas informações referentes aos efeitos da atividade residual de herbicidas aplicados na soja sobre o desenvolvimento e rendimento do girassol são conhecidas. Visando avaliar a atividade residual de herbicidas, aplicados em pré e pós-emergência na cultura da soja sobre o girassol cultivado em sucessão, foram conduzidos ensaios em campo e em casa de vegetação. No ensaio de campo, foram empregados nove tratamentos (doses em kg de i.a. ha-1): imazaquin (0,161), diclosulam (0,035), sulfentrazone (0,600) e flumioxazin (0,050), em aplicações de pré-emergência, e chlorimuron-ethyl (0,015), imazethapyr (0,060), imazethapyr (0,100) e fomesafen (0,250), aplicados em pós-emergência da soja, mais uma testemunha (sem herbicida). Um bioensaio foi conduzido em casa de vegetação com as amostras de solo dos tratamentos coletadas em seis épocas distintas (0, 35, 70, 105, 140 e 200 dias após a aplicação). Os resultados permitem concluir que o imazethapyr (0,100kg ha-1) e o diclosulam (0,035kg ha-1) causam redução no rendimento do girassol. A sensibilidade ao diclosulam perdura durante todo o cultivo do girassol.

The sunflower is a oilseed crop kind of prominence before the cultures used in succession in the Brazil. However, little information concerning the effects of residual activity of herbicides on the crop in this region are known. The aim of this study was to evaluate the residual activity of herbicides in weed management in pre and post-emergence soybean and evaluate its effects on sunflower crop in succession. In field experiments we adopted the randomized block design with four replications, being appointed nine treatments (kg of i.a. ha-1): imazaquin (0.161), diclosulan (0.035), sulfentrazone (0.600) and flumioxazin (0.050) in pre emergence applications, and chlorimuron-ethyl (0.015), imazethapyr (0.060), imazethapyr (0.100) and fomesafen (0.250) applied post emergence soybean and a control without herbicide. One bioassay was differentiated by the treatments contained in each treatment and soil samples collected at six different times (0, 35, 70, 105, 140 and 200 days after application); evaluated the dry matter accumulation of sunflower plants as a function of time of sample collection. The results showed that: imazethapyr (0.1kg ha-1) and diclosulan (0.035kg ha-1) caused a reduction in sunflower yield. Sensitivity to diclosulan continued throughout the interval evaluation of the range of bioassay.

O uso do consórcio entre plantas de cobertura e culturas anuais, no Cerrado, tem sido prática cada vez mais difundida, pela possibilidade de implantação das forrageiras durante o desenvolvimento das culturas anuais, através da diferença de profundidade e sistema de semeadura. Objetivou-se, neste trabalho avaliar a emergência e algumas características agronômicas de quatro espécies de plantas de cobertura, em diferentes profundidades, visando ao seu emprego na consorciação e sobressemeadura em culturas anuais. O experimento foi conduzido em casa-de-vegetação, no delineamento experimental de blocos ao acaso, em arranjo fatorial 4 x 7, composto pelas plantas de cobertura Brachiaria brizantha, B. decumbens, B. ruziziensis e Panicum maximum cv. Tanzânia, e por seis profundidades de semeadura e um sistema de cobertura de sementes (0 sem cobertura, 0 com cobertura, 1, 4, 8, 10 e 15 cm). As sementes foram semeadas em vasos e as plantas cultivadas por 40 dias. Avaliou-se o índice e o tempo de emergência, a altura de plantas, a fitomassa verde e seca da parte aérea, a área foliar, a fitomassa seca radicular e a densidade de comprimento radicular. O maior desenvolvimento das plantas estudadas foi detectado nas semeaduras até 1 cm de profundidade. O P. maximum não apresentou aptidão para uso em consórcio com culturas anuais.Não se recomenda a semeadura das plantas de cobertura a partir de 10 cm.

The use of the consortium between cover crops and annual crops in the Cerrado, is an increasingly widespread practice, because of the possibility of deployment of cover crops during the development of annual crops by the difference in depth and seeding system. The objective was to evaluate the emergency and some agronomic characteristics of four species of cover crops at different seeding depths, to use them in consortium and oversown in annual crops. The experiment was conducted in a greenhouse, and the experimental design of randomized blocks in factorial arranged 4 x 7, where it was four cover crops: Brachiaria brizantha, B. decumbens, B. ruziziensis and Panicum maximum cv. Tanzania, and six depths of sowing and a cover of seed system (0 cm without any mulch, 0 cm with a mulch of soybean leaves, 1, 4, 8, 10 and 15 cm). The cover crops were cropped in vase for 40 days. We evaluated emergence index, emergence time, plant height, green biomass and dry biomass of the above-ground part, leaf area, root dry biomass and root length density. The largest development of the cover crops was detected in the sowing up to 1 cm of depth. The P. maximum showed no ability to use in consortium with annual crops. The sowing of the cover crops from 10 cm is not recommended.

A aplicação do glyphosate sobre a soja resistente a este herbicida pode causar prejuízos à simbiose com o rizóbio. O objetivo deste trabalho foi avaliar a sensibilidade ao herbicida glyphosate de três estirpes de Bradyrhizobium recomendadas para a produção de inoculantes de sementes de soja no Brasil. Avaliou-se o efeito das concentrações de 0,0; 5,4; 10,8; 21,6 e 43,2 µg L-1 do ingrediente ativo do glyphosate [N-(fosfonometil) glicina] no meio YM líquido sobre o crescimento de B. japonicum (estirpe SEMIA 5079) e de B. elkanii (estirpe SEMIA 5019 e estirpe SEMIA 587), por meio de leituras das densidades óticas e geração de curvas de crescimento. As reduções de crescimento na presença da menor concentração do glyphosate foram de 18% para SEMIA 5079, 29% para SEMIA 5019 e de 35% para SEMIA 587, sendo, de modo geral, quanto maior a concentração do herbicida no meio de cultura maior a inibição do crescimento. As estirpes apresentaram sensibilidade diferencial somente às concentrações mais baixas do glyphosate; nesse caso, foi possível determinar a seguinte ordem de sensibilidade: SEMIA 587 > SEMIA 5019 > SEMIA 5079. Essa sensibilidade diferencial é dependente da concentração do herbicida, pois na presença de 43,2 µg L-1 todas as estirpes tiveram seu crescimento severamente reduzido, não havendo diferença entre elas.

Glyphosate applications to glyphosate-resistant soybean may impair symbiosis with Bradyrhizobium, a symbiotic bacterium. This study evaluated the sensitivity to glyphosate of three Bradyrhizobium strains used commercially in soybean crop in Brazil. The concentrations (0.0; 5.4; 10.8; 21.6 e 43.2 µg L-1) of the active ingredient glyphosate [N(phosphonomethyl)glycine] were added to YM liquid medium for the growth of one strain of B. japonicum (SEMIA 5079) and two strains of B. elkanni (SEMIA 5019 and SEMIA 587) inoculated as pure culture. The herbicide effect on the growth of the tested strains was assessed by optical density and growth curves were established for each strain. Reduction in growth of strains in the lowest glyphosate concentration were 18% for SEMIA 5079, 29% for SEMIA 5019 and 35% for SEMIA 587. In general, the higher the concentration of the herbicide in the culture medium, the greater the growth inhibition. The strains showed differential sensitivity only at the lowest concentrations of glyphosate, allowing the determination of the following order of sensitivity: SEMIA 587>SEMIA 5019>SEMIA 5079. This differential sensitivity is dependent on the herbicide concentration, since in the presence of 43.2 µg L-1 all strains severely reduced growth, not showing difference among them.

O longo efeito residual do herbicida picloram no solo aumenta o risco de lixiviação e de fitotoxicidade em culturas sucedâneas; sua presença no solo pode ser abreviada com o uso da fitorremediação. O objetivo deste trabalho foi avaliar a influência da densidade populacional de capim-pé-de-galinha-gigante (Eleusine coracana) sobre a fitorremediação de solo contaminado com o herbicida picloram. O experimento foi realizado em casa de vegetação localizada no município de Rio Verde-GO, no período de setembro de 2006 a fevereiro de 2007. Os tratamentos foram compostos pela combinação entre quatro densidades populacionais da espécie vegetal Eleusine coracana (capim-pé-de-galinha-gigante) (0, 7, 14 e 21 plantas por vaso, correspondendo a 0, 172, 344 e 516 plantas m-2, respectivamente) e três doses do picloram (0, 80 e 160 g ha-1 - aplicadas diretamente nos vasos, simulando níveis de contaminação do solo). Após o cultivo da espécie vegetal fitorremediadora no substrato por 100 dias, efetuou-se, no próprio vaso, a semeadura da soja (Glycine max L.), espécie utilizada como bioindicadora da presença do picloram. A espécie Eleusine coracana mostrou ter capacidade de remediar solos contaminados com o herbicida picloram. A partir de 172 plantas m-2, aumentos na densidade populacional da espécie fitorremediadora não proporcionaram redução de carryover do herbicida picloram sobre a cultura da soja semeada em sucessão.

The long-term residual effect of the herbicide picloram poses risks of leaching and phytotoxicity to successive crops. Phytoremediation can abbreviate the long carryover effect. This research was carried out from September 2006 to February 2007, under green house conditions, in Rio Verde, Goiás, Brazil, to study the influence of Eleusine coracana population density on phytoremediation of soil contaminated with picloram. The treatments consisted of the combination of four Eleusine coracana population densities (0, 7, 14 and 21 plants per pot, corresponding to 0, 172, 344 and 516 plants m-2, respectively) and three picloram rates (0, 80 and 160 g ha-1 - applied directly to the pots, simulating soil contamination levels). After growing the phytoremediation species on substrate during 100 days, soybean was sown as a bioindicator species in the same pot. E. coracana was able to remediate soils contaminanted with picloram. At densities above 172 plants m-2, there was no further reduction of the carryover effect to soybean sown in succession.