Genótipos de azevém (Lolium multiflorum Lam.) diplóides e tetraplóides são cultivados como forrageira na produção animal, no entanto, quando sistemas de produção que envolve o plantio direto são estabelecidos após o cultivo da forrageira é comum a dessecação com o herbicida glyphosate. Portanto, é importante conhecer se existe suscetibilidade diferencial a este herbicida entre os genótipos. Desta forma, foi desenvolvida a presente pesquisa como o objetivo de avaliar o grau de tolerância dos genótipos diplóides e tetraplóides de azevém ao herbicida glyphosate em quatro estádios fenológicos de desenvolvimento. Para isso, foram instalados quatro experimentos, sendo um para cada estádio fenológico do azevém (duas folhas, quatro perfilhos, pré-florescimento e formação de grãos). Os tratamentos consistiram da combinação dos dois genótipos e seis doses do herbicida glyphosate (240; 480; 960; 1.920; 3.840 e 7.680 g e.a. ha-1), e uma testemunha sem aplicação de glyphosate, em delineamento experimental de blocos ao acaso, quatro repetições. Os parâmetros analisados foram porcentagem de controle e fitomassa seca das plantas. Os resultados foram submetidos à análise de variância e em seguida ajustados para modelo de curva de dose-resposta do tipo logística, sendo destes modelos calculados valores de controle correspondestes a 50, 80, 90 e 99%. As conclusões principais obtidas nesta pesquisa foram de que os genótipos de azevém diplóide e tetraplóide apresentam suscetibilidade diferencial ao herbicida glyphosate, sendo o genótipo tetraplóide mais tolerante ao herbicida. O grau diferencial de tolerância, medido pelo fator de tolerância (FT) diferencial entre os genótipos, expresso pelo valor médio dos quatro estádios fenológicos estudados, utilizando como base o controle de 50% das plantas pelo glyphosate foi de 1,6 vezes a dose de glyphosate no genótipo tetraplóide em relação ao genótipo diplóide. Os estádios fenológicos de desenvolvimento das plantas de ambos os genótipos estudados afetam o grau de tolerância ao glyphosate. De maneira geral, em estádios mais avançados de desenvolvimento fenológico dos dois genótipos a suscetibilidade do azevém é menor ao glyphosate, exceto para o estádio de préflorescimento, no qual a planta é mais suscetível que o estádio de quatro perfilhos, quando o parâmetro de análise é a dose necessária para controle de 50% das plantas. O parâmetro de análise de suscetibilidade fitomassa seca das plantas apresentou a mesma tendência diferencial entre os fenótipos diplóides e tetraplóides que o parâmetro porcentagem de controle visual. / Diploid and tetraploid genotypes of Italian ryegrass (Lolium multiflorum Lam.) are cultivated as forage crop for animal production, however, when cropping systems that involve no tillage is established after the forage cultivation it is common the dessecation with the herbicide glyphosate. However, it is important to know if there is differential susceptibility between the genotypes to the herbicide, in four phenological stages of development. Therefore, it was developed this research with the objective of evaluating the degree of tolerance of the diploid and tetraploid genotypes of Italian ryegrass to the herbicide glyphosate. For that, four experiments were installed being one for each of the Italian ryegrass phenological stages (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 plot without glyphosate application, in randomized complete blocks design, four replications. The parameters that were analyzed were control percentage and dry biomass. Results were submitted to analysis of variance and subsequently adjusted to non linear model of logistic dose-response curves, and from these models control values were calculated at 50, 80, 90 and 99%. The main conclusions obtained in this research were that genotypes of Italian ryegrass presented differential susceptibility to the herbicide glyphosate. The differential degree of tolerance, measured by the tolerance factor (TF) between the biotypes, expressed by the mean value of the four development stages studied, using the 50% Italian ryegrass control, was 1.6 times more glyphosate rate for the tetraploid genotype compared to the diploid genotype. The phenological stages of development of both genotypes affected the tolerance degree to glyphosate. In general, the more is the advanced development stages of both biotypes, the lower is the susceptibility of Italian ryegrass to glyphosate, except for the stage of pre-flowering, in which the plant is less susceptible than the stage of four tillers, when the analyzed parameter is the rate necessary to control 50% of the plants. The parameter of analysis of susceptibility plant dry biomass presented the same tendency of differential control between the diploid and tetraploid genotypes than the visual control percentage.

Orientador: Edivaldo Domingues Velini / Banca: João Domingos Rodrigues / Banca: Marcus Barifouse Matallo / Resumo: O fósforo é um elemento essencial para todos os organismos vivos como um componente estrutural dos ácidos nucléicos e fosfolipídios. Além disso, nas plantas o fósforo é de fundamental importância na fotossíntese. A mobilização do fosfato dentro da planta é um processo complexo que requer numerosos transportadores para a sua absorção e translocação. A deficiência de fósforo é um dos maiores estresses abióticos que afetam o crescimento das plantas, especialmente em solos tropicais. O Glyphosate (N-phosphonomethyl-glycine) é o único composto comercialmente disponível que atua na enzima EPSPS. Tal composto é um herbicida sistêmico, não-seletivo, de amplo uso, com translocação via simplasto. Denis e Delrot (1993) e Morin et al. (1997) demonstraram que proteínas transportadoras de grupos fosfatos, que estão presentes na membrana plasmática de Vicia faba e Catharanthus roseus, facilitaram a absorção de glyphosate. O objetivo deste trabalho foi avaliar o efeito de subdoses de glyphosate na absorção e translocação de fósforo nas cultivares de soja, BRS 232 e BRS 243 RR. O experimento foi conduzido em casa de vegetação, e as cultivares semeadas em vasos de 8 litros. Os tratamentos foram constituídos de adubação de plantio com duas doses de 2 fósforo (50 e 150 mg L-1) e dez doses de glyphosate (0, 1,8, 3,6, 7,2, 18, 36, 72, 180, 360 e 720 g i.a. ha-1). As plantas receberam a aplicação do herbicida quando apresentaram o terceiro trifólio expandido. Após a aplicação, estas foram conduzidas por trinta dias, e então colhidas e analisadas. As análises realizadas foram: matéria seca de folha, caule e raiz, teores de fósforo e conteúdo total de fósforo das mesmas. Para a soja convencional BRS 232 (não resistente ao glyphosate) houve estímulos ao crescimento das plantas para doses entre 3,6 e 36g e.a./ha. Para esta variedade... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Phosphorous is an essential element for all living organisms acting as a structural component of nucleic acids as well as phospholipids. Besides it is of fundamental importance in photosynthesis. The maintenance of phosphate within the plant is a complex process which requires numerous transporters for its absorption and translocation. Phosphorous deficiency is one of the major abiotic stresses affecting plant growth in tropical regions. Glyphosate (N-phosphonomethyl-glycine) is the only compound commercially available which acts upon EPSPS enzyme. It is a systemic, non-selective, broad-spectrum herbicide with translocation via symplast. Transporter proteins of phosphate groups which are present at plasma membrane facilitated glyphosate absorption. This paper aims at evaluating the effects of low doses of glyphosate in phosphorous absorption and translocation in soybean crops BRS 232 e BRS 243 RR. The experiment was carried out under greenhouse conditions and plants were cultivated in 8-liter pots. The treatments were disposed in a factorial scheme combining two doses of phosphorus (50 and 150 mg L-1) and ten doses of glyphosate (0; 1.8; 3.6; 7.2; 18; 36; 72; 180; 360 and 20 g i.a. ha-1). Glyphosate was applied to plants at the third expanded three-leaf. After thirty days plants were harvested and dry matter, stems, root, phosphorous levels and the total content of phosphorous were measured. Glyphosate aplied at rates ranging from 3,6 to 36 g a.e/ha stimulated the growth and phosphorus absorption by the conventional soybean variety BRS 232 (not resistant to glyphosate) and the stronger effects were observed for the lower level of phosphorus in the soil. In this condition, glyphosate applied at 18 g a.e./ha increased in 2,61 times the phosphorus concentration in leaves. Glyphosate didn’t stimulate the growth 4 but increased the absorption of phosphorus... (Complete abstract click electronic access below) / Mestre

Genótipos de azevém (Lolium multiflorum Lam.) diplóides e tetraplóides são cultivados como forrageira na produção animal, no entanto, quando sistemas de produção que envolve o plantio direto são estabelecidos após o cultivo da forrageira é comum a dessecação com o herbicida glyphosate. Portanto, é importante conhecer se existe suscetibilidade diferencial a este herbicida entre os genótipos. Desta forma, foi desenvolvida a presente pesquisa como o objetivo de avaliar o grau de tolerância dos genótipos diplóides e tetraplóides de azevém ao herbicida glyphosate em quatro estádios fenológicos de desenvolvimento. Para isso, foram instalados quatro experimentos, sendo um para cada estádio fenológico do azevém (duas folhas, quatro perfilhos, pré-florescimento e formação de grãos). Os tratamentos consistiram da combinação dos dois genótipos e seis doses do herbicida glyphosate (240; 480; 960; 1.920; 3.840 e 7.680 g e.a. ha-1), e uma testemunha sem aplicação de glyphosate, em delineamento experimental de blocos ao acaso, quatro repetições. Os parâmetros analisados foram porcentagem de controle e fitomassa seca das plantas. Os resultados foram submetidos à análise de variância e em seguida ajustados para modelo de curva de dose-resposta do tipo logística, sendo destes modelos calculados valores de controle correspondestes a 50, 80, 90 e 99%. As conclusões principais obtidas nesta pesquisa foram de que os genótipos de azevém diplóide e tetraplóide apresentam suscetibilidade diferencial ao herbicida glyphosate, sendo o genótipo tetraplóide mais tolerante ao herbicida. O grau diferencial de tolerância, medido pelo fator de tolerância (FT) diferencial entre os genótipos, expresso pelo valor médio dos quatro estádios fenológicos estudados, utilizando como base o controle de 50% das plantas pelo glyphosate foi de 1,6 vezes a dose de glyphosate no genótipo tetraplóide em relação ao genótipo diplóide. Os estádios fenológicos de desenvolvimento das plantas de ambos os genótipos estudados afetam o grau de tolerância ao glyphosate. De maneira geral, em estádios mais avançados de desenvolvimento fenológico dos dois genótipos a suscetibilidade do azevém é menor ao glyphosate, exceto para o estádio de préflorescimento, no qual a planta é mais suscetível que o estádio de quatro perfilhos, quando o parâmetro de análise é a dose necessária para controle de 50% das plantas. O parâmetro de análise de suscetibilidade fitomassa seca das plantas apresentou a mesma tendência diferencial entre os fenótipos diplóides e tetraplóides que o parâmetro porcentagem de controle visual. / Diploid and tetraploid genotypes of Italian ryegrass (Lolium multiflorum Lam.) are cultivated as forage crop for animal production, however, when cropping systems that involve no tillage is established after the forage cultivation it is common the dessecation with the herbicide glyphosate. However, it is important to know if there is differential susceptibility between the genotypes to the herbicide, in four phenological stages of development. Therefore, it was developed this research with the objective of evaluating the degree of tolerance of the diploid and tetraploid genotypes of Italian ryegrass to the herbicide glyphosate. For that, four experiments were installed being one for each of the Italian ryegrass phenological stages (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 plot without glyphosate application, in randomized complete blocks design, four replications. The parameters that were analyzed were control percentage and dry biomass. Results were submitted to analysis of variance and subsequently adjusted to non linear model of logistic dose-response curves, and from these models control values were calculated at 50, 80, 90 and 99%. The main conclusions obtained in this research were that genotypes of Italian ryegrass presented differential susceptibility to the herbicide glyphosate. The differential degree of tolerance, measured by the tolerance factor (TF) between the biotypes, expressed by the mean value of the four development stages studied, using the 50% Italian ryegrass control, was 1.6 times more glyphosate rate for the tetraploid genotype compared to the diploid genotype. The phenological stages of development of both genotypes affected the tolerance degree to glyphosate. In general, the more is the advanced development stages of both biotypes, the lower is the susceptibility of Italian ryegrass to glyphosate, except for the stage of pre-flowering, in which the plant is less susceptible than the stage of four tillers, when the analyzed parameter is the rate necessary to control 50% of the plants. The parameter of analysis of susceptibility plant dry biomass presented the same tendency of differential control between the diploid and tetraploid genotypes than the visual control percentage.

Em 2015, o caruru palmer (Amaranthus palmeri) foi identificado pela primeira vez no Brasil, na região do núcleo algodoeiro do estado de Mato Grosso, em áreas normalmente cultivadas com rotação das culturas de algodão, soja e milho. Esta espécie possui reconhecida importância internacional, no entanto, não se conhece seu comportamento biológico nos sistemas de produção brasileiros. Ainda, também é desconhecido o grau de suscetibilidade do biótipo introduzido no país aos herbicidas, principalmente ao glyphosate e inibidores da ALS, que são os principais herbicidas utilizados para seu controle em outros países. Deste modo, este trabalho foi desenvolvido com o objetivo de caracterizar o crescimento e desenvolvimento do biótipo de A. palmeri originário do Estado do Mato Grosso, em condição de casa-de-vegetação; caracterizar o nível de resistência deste biótipo ao herbicida glyphosate (inibidor da EPSPS); verificar a existência de resistência múltipla EPSPS-ALS, bem como resistência cruzada entre os grupos químicos dos herbicidas inibidores da ALS; além de testar herbicidas alternativos aplicados em condição de pós-emergência da planta daninha. O biótipo brasileiro de A. palmeri teve rápido desenvolvimento fenológico, com início de emissão de inflorescências aos 50 dias após semeadura; o desenvolvimento fenológico de A. palmeri teve ajuste linear conforme equação y =0,8866.x; o biótipo teve acúmulo máximo de 45 g planta-1, com pico de crescimento absoluto aos 60 DAS; o crescimento da espécie foi considerado moderado quando comparado às espécies nacionais de Amaranthus, bem como aos dados internacionais de A. palmeri. Quanto aos herbicidas inibidores da EPSPS, pôde-se concluir com segurança tratar-se de biótipo resistente ao herbicida glyphosate. Ainda, constatou-se resistência múltipla aos inibidores da EPSPS-ALS. Considerando-se somente os inibidores da ALS, trata-se de população com resistência cruzada entre sulfoniluréias - triazolopirimidinas - imidazolinonas. Estas plantas foram adequadamente controladas pelos seguintes tratamentos herbicidas (g ha-1): fomesafen a 250, lactofen a 168, mesotrione + atrazina a 120 + 1.500, tembotrione + atrazina a 75,6 + 1.500, amônio glufosinato a 400 e paraquat a 400 g i.a. ha-1. O estádio de aplicação de 2 a 4 folhas, com até 5 cm de altura, é o mais indicado para o controle da planta daninha. / In 2015, Palmer amaranth (Amaranthus palmeri) was firstly identified in Brazil, at the cotton nucleus region of the State of Mato Grosso, in areas usually maintained under cotton, soybean and corn crop rotation. This species has recognized importance worldwide, however its biological behavior in Brazilian cropping systems is unknown. In addition, it is also unknown the degree of herbicide susceptibility of the biotype introduced in the country, mainly its susceptibility to glyphosate and ALS inhibiting herbicides, that are the main products used to control this species in other countries. Therefore, this work was developed with the objective of characterizing growth and development of the A. palmeri biotype collected in the state of Mato Grosso, Brazil, under greenhouse condition; verifying the resistance level of this biotype to glyphosate (EPSPS inhibiting herbicide); verifying the existence of EPSPS-ALS multiple resistance, as well as crusade resistance between chemical groups of ALS-inhibiting herbicides; testing alternative herbicides for post-emergence control of this weed. Brazilian biotype of A. palmeri had fast phenological development, with beginning of flowering at 50 days after seeding. Species phenology was adjusted to the linear equation y =0,8866.x. In average, the maximum dry matter accumulated was 45 g plant-1, with edge of absolute growth at 60 DAS. In conclusion, growth parameters of the Brazilian biotype of A. palmeri were considered moderated when compared to national species of Amaranthus, as well as with international data of A. palmeri. Regarding to EPSPS inhibiting herbicides, it was possible to conclude that Brazilian biotype of A. palmeri is glyphosate resistant. Therefore, multiple resistance to EPSPS-ALS inhibiting herbicides was also identified. Considering exclusively ALS-inhibiting herbicides, this population has sulfonilurea-triazolopirimidine-imidazolinone crusade resistance. Plants were adequately controlled with the following herbicides (g ha-1): fomesafen at 250, lactofen at 168, mesotrione + atrazine at 120 + 1,500, tembotrione + atrazine a 75.6 + 1,500, ammonium-glufosinate at 400 and paraquat at 400. Phenological stage of 2 to 4 leaves, with up to 5 cm of height, was the most indicated to Palmer amaranth control.

Cette étude vise à développer un système de dépollution d'eau et de sédiments viticoles. Le glyphosate, diuron et 3,4-dichloroaniline (3,4-DCA) sont considérés, en tenant compte de la charge en cuivre. L'augmentation du temps de séjour des polluants dans le système et le choix de la bioaugmentation couplée à la phytoremédiation est la stratégie retenue. Chaque composante d'un triplet « sorbant-inoculum bactérien-plante » a été sélectionnée en laboratoire et le triplet mis en oeuvre en microcosmes en conditions partiellement contrôlées.La sélection de matériaux sorbants dans différentes matrices liquides en présence des polluants seuls ou en mélange montre que les capacités de sorption des différents matériaux testés varient selon le polluant, sa formulation (seul ou en mélange) et la matrice liquide. Le sédiment se révèle être le meilleur sorbant pour le glyphosate ; le sable pour le diuron et le 3,4-DCA.Les performances de dissipation des colonies tolérantes isolées varient fortement selon le polluant. Le consortium sélectionné pour le procédé dissipe le glyphosate, le diuron et le 3,4-DCA en milieu liquide et complexe par ailleurs le cuivre.L'expérience en microcosmes montre que le temps de rétention hydraulique influe sur l'efficacité du système et que les matériaux sorbants sont efficaces. De plus les performances de dissipation atteintes sont bonnes. L'effet de la bioaugmentation sur les performances de dissipation n'est pas significatif pour le glyphosate et le 3,4-DCA, mais améliore en moyenne la dissipation du diuron. Un temps d'action prolongé dans la matrice solide s'avère nécessaire pour obtenir une bonne efficacité du procédé. / This study aims at developing a depollution system for vineyard sediments and passing water. Glyphosate, diuron and 3,4-dichloroaniline (3,4-DCA) have been chosen, taking a copper load into account. Strategical choices are increased pollutant hydraulic retention time and the use of bioaugmentation together with phytoextraction. Each item on this « sorbent-bacterial inoculum-plant » triplet has been beforehand selected in the laboratory and implemented in microcosm experiments under semi-controlled conditions.Sorbent material selection in different liquid matrices with pollutants alone or in combination shows that material sorption capacities change with the type of pollutant. It has also been shown that these capacities vary with formulation (alone or in combination) and liquid matrix chosen. Sediment is awarded the best sorbent for glyphosate, sand the best sorbent for diuron and 3,4-DCA.Dissipation performances from isolated colonies are strongly related to the nature of the compound. Elected consortium degrades glyphosate, diuron and 3,4-dichloroaniline (3,4-DCA) in liquid culture as well as it complexes copper.Microcosm experiments show that hydraulic retention time weighs on pollutant concentration in water at the system outlet. Sorbents prove to be efficient. Dissipation performances are satisfactory. Bioaugmentation does not impact on glyphosate and 3,4-DCA dissipation performances significantly, but enhances diuron dissipation in average. Suitable process efficiency requires increased action time within the solid matrix.

L’élimination des produits agrochimiques indésirables des eaux de drainage agricole dans les bassins versants peut être réalisée par des zones humides ouvragées. Les oxy-hydroxydes de fer sont parmi les composés les plus réactifs chimiquement dans les sols tempérés et pourraient être un support idéal en mélange avec un support traditionnel pour la végétation dans ces systèmes. Le présent mémoire expose un travail de recherche visant à tester l’efficacité d’un procédé novateur d’élimination du glyphosate par un filtre minéral planté qui utilise les propriétés d’un support de grande surface spécifique composé d’oxy-hydroxyde ferrique et de végétaux adaptés aux zones humides et tolérants au glyphosate. Ce travail présente trois axes principaux qui sont : • la caractérisation physico-chimique de deux supports synthétiques choisis pour leur potentiel à retenir le glyphosate et de choisir le plus approprié pour notre étude • une étude mécaniste approfondie de l’adsorption du glyphosate sur le support retenu a été faite, suivie d’une analyse comparée de l’adsorption de glyphosate avec celle du phosphate sur ce même support. • la culture de différentes associations à partir de deux espèces végétales de milieu humide (Lythrum salicaria et Phragmites australis) sur un mélange de (sable, support adsorbant) arrosées par irrigation en présence ou en absence de glyphosate et de phosphate afin de vérifier l’efficacité du dispositif sur la dégradation de glyphosate. Les résultats obtenus de la caractérisation nous ont dirigés vers le minéral synthétique GEH®104, (GEH Wasserchemie GmbH & Co. KG, Heinrich-Hasemeier-Straße 33, D-49076 Osnabrück) qui est presque une akaganeite pure avec une surface spécifique de 350 m2.gr-1. Les cinétiques d’adsorption ont suggéré que le temps d’équilibre était plus long (15 j) que le temps déclaré dans la littérature pour des phases similaires. Cela est attribué à la nature mésoporeuse du support utilisé. L’akaganeite adsorbe le glyphosate fortement suivant deux modes : le premier est presque irréversible suivi par un mode hyperbolique, suivant l’équation de Langmuir double, alors que l’adsorption du phosphate suit plutôt l’équation de Bradley. La grande capacité d’adsorption de glyphosate et de phosphate par l’akaganeite en fait un candidat approprié pour une implication dans des zones humides ouvragées devant traiter des eaux contenant ces polluants. Les expériences de culture ont montré que Phragmites australis et la Lythrum Salicaria L. peuvent supporter de fortes concentrations de glyphosate par irrigation et qu’ils bénéficient de l’association mutuelle. Il semblerait que les plantes et leurs micro-organismes associés assurent l’essentiel de la disparition du glyphosate en solution car une fois bien installées, le glyphosate et ses métabolites ne sont pratiquement plus détectables en solution. Le système complet empêche le glyphosate de percoler lorsque celui-ci est présent avec ou sans phosphate dans les eaux d’irrigation / The elimination of undesirable agrochemicals of agricultural drainage water in watersheds can be achieved through engineered wetlands. Iron oxy-hydroxides are among the most chemically reactive compounds in temperate soil and they could be an ideal support in admixture with a traditional holder for vegetation in these systems. This work aimed to test the effectiveness of an innovative method of removing glyphosate mineral planted by a filter that uses the properties of a high surface area carrier composed of ferric oxyhydroxide and plants adapted to wetlands and tolerant to glyphosate. This work has three main axis which are: • The physicochemical characterization of two synthetic materials chosen for their potential to retain glyphosate and choose the most suitable for our study. • A profound mechanism study of the adsorption of glyphosate on the chosen support has been made, followed by a comparative analysis of the glyphosate with the adsorption of phosphate on the same support. • culture of different associations based on two plant species of wetland (Lythrum salicaria and Phragmites australis) on a mixture of (sand, adsorbent support) watered by irrigation in the presence or absence of glyphosate and phosphate to verify the effectiveness of the device on the degradation of glyphosate. The results of the characterization directed us to the synthetic mineral GEH®104 (GEH Wasserchemie GmbH & Co. KG, Heinrich-Hasemeier Straße 33, D-49076 Osnabrück) which is almost a pure akaganeite with a surface area of 350 m2.gr-1. The adsorption kinetics suggested that the equilibrium time was longer than (15 days), which is longer than the time reported in the literature for similar phases. This is attributed to the mesoporous nature of the support used. Akaganeite strongly adsorbs glyphosate in two modes: the first is almost irreversible followed by a hyperbolic mode, according to the Dual Langmuir’s equation while the phosphate adsorption follows the Bradley’s equation. The large capacity of adsorption of glyphosate and phosphate by actually akaganeite makes it a suitable candidate for involvement in wetlands engineered to treat water containing these pollutants. The experimental cultural showed that reed and purple loosestrife can support high concentrations of glyphosate by irrigation and they benefit from membership organization. It appears that plants and their associated microorganisms are responsible for most of the disappearance of glyphosate in solution because once properly installed, glyphosate and its metabolites are practically no longer detectable in solution. The complete system prevents glyphosate from percolating when it is present with or without phosphate in the irrigation water

The expression of glyphosate resistance can vary within single field populations of common waterhemp and Palmer amaranth. This variability in expression can translate into control ranging from 20 to 80%, which could be the difference in a minor versus a major failure in weed management. Certain application parameters that have been previously associated with glyphosate efficacy, such as glyphosate application time of day and plant stress may exacerbate this variability and lead to failed control of plants on the lower end of the resistance spectrum. Greenhouse research was conducted in 2011 to determine the influence of glyphosate application time of day on the expression of resistance in common waterhemp and Palmer amaranth. Control of both glyphosate-susceptible (GS) and -resistant (GR) weed species showed similar trends in response to glyphosate with respect time of application. Decreased sensitivity of all Amaranthus biotypes was greatest at 9:00 pm and may be attributed to an observed shift in leaf orientation from horizontal to vertical at the time of glyphosate application in response to low-light conditions. The altered leaf orientation most likely reduced herbicide spray coverage. The magnitude of resistance, the difference in the sensitivity of the resistant versus susceptible biotypes, was unaffected by glyphosate application time of day; however, these results indicate that even in resistant populations glyphosate applied at suboptimal times of day such as the evening can cause a further increase in weed escapes from glyphosate. Greenhouse and field experiments were conducted in 2011 and 2012 to determine the influence the soil nutrient amendments on glyphosate sensitivity and growth rate and of GS and GR common waterhemp and Palmer amaranth. In both the GR and GS biotypes of common waterhemp the sensitivity to glyphosate was increased as fertilizer was introduced. However, only the sensitivity of the susceptible biotype of Palmer amaranth was increased with the addition of fertilizer. The lack of response in the GR Palmer amaranth population to fertilizer can be associated with the fact that due to carrier volume limitations enough glyphosate could not be applied to achieve 50% control. The magnitude of resistance was decreased numerically with the addition of fertilizer in both weed species; however, only in common waterhemp was the magnitude of resistance significantly different with the use of high rates fertilizer. The use of fertilizer also had an influence on the growth rate and dormancy of axillary buds. Lateral branching (broken dormancy in axillary buds) was increased in both common waterhemp and Palmer amaranth with the addition of fertilizer. Converting dormant buds to active meristems favors glyphosate translocation and could be responsible for increased glyphosate efficacy. In the field, glyphosate efficacy in GR common waterhemp and Palmer amaranth was also increased with addition of fertilizer; however, this effect was variable. Optimizing the efficacy of glyphosate when applied to even mixed populations of GS and GR Palmer amaranth and common waterhemp can reduce surviving weeds that can produce seed and perpetuate the frequency of glyphosate resistance in the field. Furthermore, greater efficacy of glyphosate may translate into relatively less significant failures in glyphosate applications allowing for successful rescue herbicide treatments and minimal impact on crop yield compared with a complete glyphosate failure with dramatic implications on reduced crop yield and increased weed seed production.

Master of Science / Agronomy / Johanna A. Dille / Mithila Jugulam / Common lambsquarters (Chenopodium album L.) is an annual broadleaf weed species that competes with more than 40 crop species around the world. A biotype of common lambsquarters in north central KS (DK) was not controlled by a glyphosate application. Plant growth stage and temperature have been related to overall glyphosate efficacy on common lambsquarters. The objectives were to determine the: 1) tolerance of two biotypes of common lambsquarters to glyphosate, 2) efficacy of glyphosate on common lambsquarters at different growth stages, and 3) efficacy of glyphosate on common lambsquarters when grown at different temperatures. Greenhouse dose-response experiments, shikimate accumulation assay, and glyphosate uptake and translocation experiments were conducted using DK biotype and a known susceptible biotype (RL) of common lambsquarters for comparison. Dose-response results indicated elevated tolerance of the DK biotype to glyphosate based on the GR₅₀ (a dose causing 50% biomass reduction) values (373 g ae/ha for RL vs. 552 g ae/ha for DK). Similarly, the DK biotype accumulated slightly less shikimate in the leaf discs compared to the RL biotype. Minimal differences were observed in ¹⁴C-glyphosate uptake and translocation between the two biotypes. Greenhouse-grown common lambsquarters were treated with glyphosate at a field dose (1x) of 840 g ae/ha when they were 5-7, 10-12, 15-17 or 19-21 cm tall. Common lambsquarters were also grown in growth chambers for 1 wk maintained at d/n temperatures of 25/15, 32.5/22.5, or 40/30 C and then treated with 0-, 0.125-, 0.25-, 0.5-, 0.75, 1.0-, and 2.0-x rates of glyphosate at 8-10 cm tall. Visual injury was recorded 1 WAT and biomass was determined 2 WAT. Common lambsquarters plants treated at 5-7 cm were more susceptible than larger plants to glyphosate. Furthermore, plants were more susceptible to glyphosate when grown under lower temperatures of 25/15 C than higher temperatures. Overall, these results suggest that the DK biotype of common lambsquarters appears to have elevated tolerance to glyphosate. Additionally, glyphosate should be applied early in the season when plants are small and temperatures are cooler for optimal control of common lambsquarters.

Made available in DSpace on 2015-03-26T13:39:37Z (GMT). No. of bitstreams: 1 texto completo.pdf: 426054 bytes, checksum: c0ad434551aa86070264961654fb175e (MD5) Previous issue date: 2010-07-05 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Experiments were carried out at the Experimental Station of Coimbra, Minas Gerais, of the Department of Plant Science of the Universidade Federal de Viçosa to study the effect of Mo in mixture with glyphosate, applied on corn and brachiaria straw on bean plant crop under no-till system. Two field assays were carried out, the first on brachiaria straw and the second on corn straw. The experiment was set up in split-plots, with the plots consisting of five doses of molybdenum (0, 100, 200, 400 and 800 g ha-1), applied in combination with the a desiccating herbicide (glyphosate) and the split-plots consisting of two doses of molybdenum (0 and 100 g ha-1), applied via the leaves on the bean plant, in the DBC, with four repetitions. Each split-plot was composed by five 5 m long, 0.5 m spaced lines of bean plant, cultivar Ouro Vermelho. Molybdenum foliar fertilization was carried out at stage V4, with sodium molybdate (39% of Mo) being the source of Mo. The content of chlorophyll was evaluated in the third completely expanded leaf from the apex (index leaf), through the SPAD index (Soil Plant Analyses Development), with three readings per leaflet being carried out in ten leaves randomly selected from the split-plot plants. The contents of N, P, K, Ca, Mg, S, Mn, Zn, Cu and Mo were evaluated in the leaves and grains under laboratory conditions. The number of plants per hectare (NP), number of pods per plant (NPP), number of grains per pod (NGP), mass of 100 grains (MG) and yield (Y) were later determined. The bean plant cultivated on the brachiaria straw absorbed MO applied on the latter, combined with glyphosate, increasing its yield. The content of Mo in the leaves increased in response to the application of the micronutrient, in mixture with glyphosate. Its concentration was even greater in the grains, when Mo was also applied via the leaves. The foliar content of nitrogen increased with the application of Mo mixed with glyphosate, when the micronutrient was not applied on the bean plant leaves, presenting a behavior similar to the SPAD index. When, besides the mixture of Mo with glyphosate, the former was applied via the leaves on the bean plants, these two factors decreased slightly. P content in the grains reduced when Mo was applied via the leaves. The content of K in the grains increased with the increase of the molybdenum dose, applied together with glyphosate on the brachiaria straw. On the other hand, when the bean plant was cultivated on the corn straw, the number of pods per plant (NPP) increased in response to the application of the Mo mixtures with glyphosate, when there was no foliar application of Mo on the bean plant. The foliar content of Mo was higher in the treatment Mo was applied on the bean plant leaves, regardless of the dose of this micronutrient, mixed with glyphosate. The content of Mo in the grains increased linearly with the increase of the micronutrient dose, applied together with glyphosate. The SPAD index was not altered, regardless of the Mo dose applied together with glyphosate, and/or applied via the leaves on the bean plant. / Com o objetivo de estudar o efeito do Mo em mistura com o dessecante, aplicado sobre palhadas de milho e braquiária para o plantio direto do feijoeiro, foram conduzidos experimentos na estação experimental de Coimbra, Minas Gerais, pertencente ao Departamento de Fitotecnia da Universidade Federal de Viçosa. Realizaram-se dois ensaios em campo, sendo o primeiro sobre palhada de braquiária e o segundo sobre palhada de milho. O experimento foi implantado utilizando-se parcelas subdivididas, sendo as parcelas constituídas por cinco doses de molibdênio (0, 100, 200, 400 e 800 g ha-1), aplicadas juntamente com o herbicida dessecante (glyphosate) e as subparcelas constituídas por duas doses de molibdênio (0 e 100 g ha-1), aplicadas via foliar no feijoeiro, no DBC, com quatro repetições. Cada subparcela foi composta por cinco linhas de feijão, cultivar Ouro Vermelho, com 5 m de comprimento, espaçadas de 0,5 m. A adubação foliar molíbdica foi realizada no estádio V4, sendo o molibdato de sódio (39% de Mo) a fonte de Mo. Avaliaram-se o conteúdo de clorofila na terceira folha completamente expandida a partir do ápice (folha índice), através do índice SPAD (Soil Plant Analyses Development), sendo realizadas três leituras por folíolo em dez folhas tomadas aleatoriamente nas plantas da subparcela. Em laboratório foram avaliados os teores de N, P, K, Ca, Mg, S, Mn, Zn, Cu e Mo, nas folhas e nos grãos. Posteriormente, foi determinado o número de plantas por hectare (NP), o número de vagens por planta (NVP), o número de grãos por vagem (NGP), a massa de 100 grãos (MG) e a produtividade (P). O feijoeiro cultivado sobre palhada de braquiária absorveu o Mo aplicado na braquiária, junto com o dessecante, aumentando sua produtividade. O teor de Mo nas folhas aumentou em resposta à aplicação do micronutriente, em mistura com o dessecante. Nos grãos, a sua concentração foi ainda maior, quando o Mo foi, também, aplicado via foliar. O teor foliar de nitrogênio aumentou com a aplicação de Mo misturado com o dessecante, quando não houve aplicação deste micronutriente nas folhas do feijoeiro, apresentando comportamento semelhante ao índice SPAD. Quando além da mistura do Mo com o dessecante houve aplicação do mesmo via foliar no feijoeiro, estes dois fatores diminuíram ligeiramente. O teor de P nos grãos reduziu quando o Mo foi aplicado via foliar. O teor K nos grãos aumentou com o aumento da dose de molibdênio aplicada junto com o dessecante na palhada da braquiária. Por outro lado, quando o feijoeiro foi cultivado sobre palhada de milho, o número de vagens por planta (NVP) aumentou em resposta à aplicação das misturas do Mo com o dessecante, quando não houve aplicação foliar de Mo sobre o feijoeiro. O teor foliar de Mo foi superior no tratamento que houve aplicação do mesmo nas folhas do feijoeiro, independentemente da dose deste micronutriente misturado com o dessecante. O teor de Mo nos grãos aumentou de forma linear com o aumento da dose do micronutriente aplicado junto com o dessecante. O índice SPAD não foi alterado, independentemente da dose de Mo aplicada juntamente com o dessecante e ou aplicado via foliar no feijoeiro.

Made available in DSpace on 2015-03-26T13:51:44Z (GMT). No. of bitstreams: 1 01 - capa_abstract.pdf: 76671 bytes, checksum: 6479c7684e1e1f9436c94cf7407a6fac (MD5) Previous issue date: 2007-08-17 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of this work was to evaluate the role of soil microorganisms in the availability of insoluble phosphate sources and to study the sensibility of phosphate solubilizing bacteria to commercial formulations of glyphosate. Rhizosphere soil samples were collected from Eucalyptus grandis x Eucalyptus urophylla hybrids with different diameters at breast height, planted at distinct topographical regions, namely top, slope, and lowland. Acid phosphatase activity varied from 24.40 to 190.07 μg p-nitrophenol g-1 soil h-1, while alkaline phosphatase showed values ranging from 0.70 to 20.55 μg p-nitrophenol g-1 soil h-1. The highest phosphatase activity was observed for the rizhosphere soli from plants located at the top region. The solubilization potential of Ca, Fe and Al phosphates by the soil microorganisms varied from 17.38 to 7949.71 μg P g-1 dry soil. Calcium phosphate promoted the highest values for phosphate solubilization. The solubilization potential for Catalão and Araxá rock phosphates varied from 27.08 to 1209.71 μg P g-1 dry soil, and Catalão phosphate was the most soluble phosphate source. The final pH of the culture medium was negatively correlated to phosphate solubilization. Rhizosphere bacteria were isolated and characterized as to their phosphate solubilization capacity. The solubilization index (SI) for calcium phosphate by the bacterial isolates grown in solid medium varied from 0 to 4.07. The amount of solubilized phosphate in liquid medium varied from 80.17 to 22,259.33 μg P. The growth and the phosphate solubilization capacity of the isolates were also evaluated in the presence of the commercial formulations Roundup Transorb®, Roundup NA®, Zapp QI®, and Scout®. The presence of the herbicides in the culture medium caused a significant reduction in the growth of the isolates tested. For the isolate To 66, the presence of Roundup Transorb® and Zapp QI® significantly reduced the phosphate solubilization potential of this isolate, while for Scout the reverse was observed. The tested formulations affected the growth and solubilization capacity of some of the isolates in vitro. It is hypothesized that such effect resulted from specific components of the tested formulations and not from glyphosate itself, once the herbicide was present at the same concentration in each of the commercial formulations tested. Further investigations on the action of these substances on the soil microbiota must be conducted in situ for a better understanding of the potential deleterious effects of such formulations on key processes that take place in the soil. / Objetivou-se neste trabalho avaliar o papel dos microrganismos do solo na solubilização de fontes insolúveis de fósforo, bem como a sensibilidade de bactérias solubilizadoras de fosfato a formulações comerciais de glyphosate. A atividade de fosfatases e o potencial de solubilização, em meio NBRIP líquido, dos fosfatos de cálcio, ferro e alumínio, e dos fosfatos naturais de Araxá e Catalão pela microbiota total do solo rizosférico de plantas do híbrido Eucalyptus grandis x Eucalyptus urophylla com diferentes diâmetros à altura do peito, oriundas de posições topográficas distintas, a saber, topo, encosta e baixada, foram avaliados in vitro. Procedeu-se também o isolamento de bactérias da rizosfera destas plantas e a sua caracterização quanto à capacidade de solubilização de fosfato de cálcio, por meio da determinação do índice de solubilização em meio sólido. O crescimento e a capacidade de solubilização de fosfato dessas bactérias foram também avaliados em meio líquido, na presença das formulações comerciais Roundup Transorb®, Roundup NA®, Zapp QI® e Scout®. Os solos coletados de plantas do topo e da baixada apresentaram maior solubilização de fosfato de cálcio pela microbiota, enquanto o solo da encosta não apresentou diferenças entre as fontes inorgânicas testadas. O fosfato de Catalão foi a fonte natural mais solubilizada pela microbiota do solo. O pH final do meio de cultura correlacionou-se negativamente com os valores de fósforo solubilizado. A atividade das fosfatases ácida e alcalina foi maior nos solos rizosféricos de plantas do topo. Os isolados obtidos apresentaram diferenças quanto ao índice de solubilização (IS) de fosfato de cálcio, apresentando valores entre zero, relativo aos isolados que perderam a capacidade de solubilização, e 4,07. Também foram observadas diferenças entre os isolados quanto à sua capacidade de solubilização de fosfato em meio líquido. A presença de herbicidas no meio de cultura reduziu significativamente o crescimento de todos os isolados testados. Os isolados To 66 e To 3 foram os mais sensíveis à presença do herbicida Roundup Transorb®. Para o isolado To 66, a adição ao meio de cultura de Roundup Transorb® e Zapp QI® reduziu significativamente o potencial de solubilização deste isolado, enquanto o herbicida Scout® teve efeito oposto. O potencial de solubilização do isolado To 11 não foi alterado na presença dos herbicidas. Os herbicidas testados afetam o crescimento e a capacidade de solubilização de alguns isolados in vitro, sendo necessário investigar se esse efeito também ocorre no solo.