Master of Science / Department of Agronomy / Johanna A. Dille / Curtis R. Thompson / The acetolactate synthase inhibitor herbicide-resistant grain sorghum technology introduced will allow for the application of nicosulfuron for postemergence (POST) grass control, however it is essential to determine a program-based approach to ensure broad spectrum weed control. Field experiments were conducted at three locations across Kansas in 2015 and 2016 to assess a range of possible herbicide programs for grass and broadleaf weed control and crop tolerance using Inzen™ Sorghum. The experiments consisted of 1 early pre-plant (EPP), 2 preemergence (PRE), and 3 POST, and 5 PRE followed by POST herbicide treatments. Weed control and crop response were evaluated visually at 1, 2, and 4 weeks after POST treatment (WAPT). Treatments containing nicosulfuron and/or bromoxynil & pyrasulfotole caused 10 to 20% crop injury at 1 WAPT in both 2015 and 2016 at the three locations. Treatments containing nicosulfuron + dicamba caused up to 30% injury with more injury in 2015 than in 2016. In 2015 at Manhattan the nicosulfuron-only treatment provided 64% control of Palmer amaranth and, when tank mixed with dicamba or bromoxynil & pyrasulfotole, control ranged from 71 to 76%. When nicosulfuron POST followed PRE of S-metolachlor & atrazine, Palmer amaranth control was 96 to 100%. At both locations, nicosulfuron provided 35, 55, and 61% control of large crabgrass, yellow foxtail, and stinkgrass, respectively. Annual grass control ranged from 85 to 100% when nicosulfuron followed a PRE S-metolachlor & atrazine. Greenhouse experiments were set up to determine the efficacy of nicosulfuron on four annual grass species at six different rates, two different rates, and the addition of atrazine. The four grass species evaluated were large crabgrass, yellow foxtail, barnyardgrass, and wheat. Nicosulfuron was applied at 0.125, 0.25, 0.5, 1, 2 times its labeled rate of 35 g ha⁻¹. A full factorial of rate by height by atrazine was applied for a total of 24 treatments replicated 4 times on each species. Each nicosulfuron rate was applied with and without atrazine at 840 g ha⁻¹ on 5 to 10 cm tall plants and on 15 to 20 cm tall plants. Visual ratings were taken 1, 2, and 4 weeks after treatment (WAT). Aboveground biomass was harvested 4 WAT, dried and weighed. Treatments containing nicosulfuron from 4.4 to 70 g ha⁻¹ all caused similar reduction in biomass compared to the nontreated check. Averaged over the inclusion of atrazine, nicosulfuron applied at 35 and 70 g ha⁻¹ provided 17% less control when treating 15 to 20 cm large crabgrass compared to the 5 to 10 cm large crabgrass, respectively. Overall barnyardgrass, yellow foxtail, and wheat can be effectively controlled with nicosulfuron when applied at proper heights, rate, and atrazine.

Orientador: José de Alencar Simoni / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T20:46:57Z (GMT). No. of bitstreams: 1 Curti_GabrielJeronymo_D.pdf: 2740453 bytes, checksum: e587cb4af6da5b69a349e04e62b2a63c (MD5) Previous issue date: 2014 / Resumo: Sabe-se que na agricultura a qualidade de um solo é dependente do tipo de manejo. No presente trabalho foi aplicada a microcalorimetria isotérmica para se investigar a influência do herbicida atrazina na atividade microbiana de um solo envelhecido de mata nativa, mantido a aproximadamente 4 °C, durante três anos. Além da utilização da microcalorimetria isotérmica, foram realizadas as análises de DSC e TG com a finalidade de se avaliar a quantidade de matéria orgânica presente no solo estudado, cujo valor quantificado foi de (3,5 ± 0,2)% g/g. Também foi realizado o cálculo da humidade do solo e as análises elementares [CHN e EDS (Energy Dispersive X-Ray Detector) acoplado ao MEV (Microscópio Eletrônico de Varredura)]. As amostras de solo utilizadas na análise microcalorimétrica foram previamente incubadas com acetonitrila e com soluções de atrazina em acetonitrila nas concentrações de 1000 e 2000 ppm, durante aproximadamente 48 horas. Em seguida, foi descoberto com o emprego da microcalorimetria isotérmica que a acetonitrila ainda permanecia no solo após o período de incubação, além do fato de que o efeito da atrazina sobre os microrganismos do solo não era detectável, uma vez que os valores para o calor gerado durante a incubação com aquele solvente e com as soluções de atrazina em acetonitrila nas concentrações de 1000 e 2000 ppm, respectivamente, eram iguais a: (-12,8 ± 0,8), (-12,9 ± 0,9) e (-13,5 ± 0,6) J, enquanto que os valores da constante do crescimento microbiano eram iguais a: (5,9 ± 1,4), (6,8 ± 1,6) e 6,37 min-1. A análise microbiológica também indicou que a atrazina não estaria influenciando os microrganismos, diferentemente do caso da acetonitrila, a qual foi responsável por uma redução nas quantidades dos microrganismos. No presente trabalho também foi investigada a influência do herbicida nicosulfuron sobre as atividades microbianas nos solos de mata nativa ou floresta e de cultivos do milho e do café. Foram empregadas as mesmas técnicas analíticas como no caso da atrazina, sendo que para se estudar o nicosulfuron foram investigadas as seguintes condições de incubação (durante 48 h) para cada tipo de solo: aplicação de acetonitrila, aplicação de uma solução de nicosulfuron em acetonitrila com uma concentração igual a 64 ppm e aplicação de uma solução com a mesma natureza, mas com uma concentração igual a 120 ppm. Os resultados indicaram que o solo de floresta era o mais rico em termos de matéria orgânica (4,0 ± 0,1)%, enquanto que o solo de cultivo do café era o mais rico em termos de humidade (21 %). Preliminarmente, as análises térmicas realizadas com o auxílio da microcalorimetria isotérmica indicaram que a acetonitrila foi novamente a espécie mais biodegradada, ao passo que nos casos das condições em que havia adição de água ao invés da solução de glicose pôde ser concluído que o solo cultivado com café foi aquele que mais sofreu influência do nicosulfuron do que nos casos dos outros solos, uma vez que para o valor de concentração mais elevado, i.e., 120 ppm, o valor da energia dissipada (calor; Q) foi estatisticamente superior (-6,6±0,3)J do que no caso da solução da mesma natureza com concentração igual a 64 ppm (-4,8±0,9)J. Para os solos de floresta ou mata nativa e de cultivo do milho o nicosulfuron não exerceu influência detectável. As análises microbiológicas para os solos de cultivo do café e do milho não indicam que ocorram diferenças estatisticamente significativas para algumas das condições estudadas, de tal maneira que para o estudo com o nicosulfuron podemos concluir que a microcalorimetria isotérmica se mostra uma técnica promissora que pode permitir estudos com xenobióticos como os pesticidas / Abstract: It is known in agriculture that soil quality does dependent on the kind of soil management. In the present work was applied the isothermal microcalorimetry to investigate the influence of the herbicide atrazine on the microbial activity of a forest soil that was aged (resting along 3 years under about 4°C). Besides the application of isothermal microcalorimetry it were performed the DSC and TG analyses with the purpose to evaluated the amount of organic matter present in the soil whose value was equal to (3.5±0.2) % to the studied soil. It were also performed the calculation of humidity in the soil and the elemental analyses [CHN and EDS (Energy Dispersive X-Ray Detector) coupled to SEM (Scanning Electron Microscopy)]. The soil samples used for the microcalorimetric analysis were previously incubated with acetonitrile and atrazine solutions in acetonitrile (1000 ppm and 2000 ppm), during approximately 48 hours. Afterwards, with the aid of the Isothermal Microcalorimetry it was discovered that actually the acetonitrile was remaining in the soil, even after the incubation period and that the effect of atrazine on the soil microorganisms was undetectable, once the heat generated for the incubation with acetonitrile and with atrazine solutions in acetonitrile of 1000 and 2000 ppm were equal respectively to: (-12.8 ± 0.8); (-12.9 ± 0.9) and (-13.5 ± 0.6) J, whilst that the values of the microbial growth constant were equal to: (5.9±1.4); (6.8±1.6) and 6.37 min-1. The microbiological analysis also indicated that the atrazine was not influencing the microorganisms, differently for the case of acetonitrile that was responsible for a decrease on the amounts of them. It was also investigated in that work the influence of the herbicide nicosulfuron on the microbial activities of soils under forest, and under maize and coffe tree crops. The same kind of analyses were performed as for the case of atrazine, but the investigations occured after a previous period of incubation along 48 h, and the conditions evaluated were: application of acetonitrile, application of nicosulfuron solution in acetonitrile with concentration equal to 64 ppm and application of a solution with the same nature but with concentration equal to 120 ppm. The results indicated that the forest soil was the richest one in terms of organic matter ( 4.0 ± 0.1) % , whilst the soil that lies under a coffe tree crop was the richest one in terms of humidity (21 % ). The thermal analyses with the aid of the Isothermal Microcalorimetry indicated preliminary that again acetonitrile was biodegradated mostly. However, for the soil tilled under coffe tree crop, considering the same conditions discussed previously for nicosulfuron but with the addition of deionized water after 48 h, the microbial activity was more stimulated by the nicosulfuron than respect to the other conditions, once with the solution of nicosulfuron with the highest concentration, i. e., 120 ppm, the value for the heat dissipated (Q) was statistically higher (-6.6±0.3) than for the concentration equal to 64 ppm (- 4.8 ± 0.9), while that in the forest soil and for the soil tilled with maize crop its influence was undetectable. The microbiological analysis for the forest soil and for the soil under maize crop shown that there are no differences that are statistically significant for some conditions studied, in such a way that for the study with nicosulfuron we can conclude that the Isothermal Microcalorimetry shows itself a promising technique that can allow studies with xenobiotics as the pesticides / Doutorado / Físico-Química / Doutor em Ciências

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2018-09-28T13:44:38Z No. of bitstreams: 1 texto completo.pdf: 610162 bytes, checksum: 45a143e15c8f7476ce467f0b8be3b7f3 (MD5) / Made available in DSpace on 2018-09-28T13:44:38Z (GMT). No. of bitstreams: 1 texto completo.pdf: 610162 bytes, checksum: 45a143e15c8f7476ce467f0b8be3b7f3 (MD5) Previous issue date: 2018-03-01 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A integração lavoura pecuária promove a consorciação e/ou sucessão das atividades agrícola e pecuária dentro da propriedade rural. A semeadura a lanço é uma alternativa viável para este sistema, no entanto, ainda se carece de informações quanto a época de semeadura aliada a doses de herbicidas a fim de retardar o crescimento excessivo da forrageira, e como a fertilidade do solo influencia neste sistema. Deste modo, objetivou-se com este trabalho avaliar os componentes de rendimento e características agronômicas do milho, e a cobertura do solo promovida pelas plantas de Urochloa ruziziensis em consórcio com milho em função das épocas de semeadura da forrageira a lanço e doses do herbicida nicosulfuron em dois níveis de adubação. Dois experimentos foram conduzidos em Coimbra, MG. Estabeleceu-se uma população de milho de 70 mil plantas ha -1 e a densidade de semeadura da U. ruziziensis em 6 kg de sementes ha -1 . O delineamento utilizado foi de blocos ao acaso, em esquema fatorial 4x4, avaliando-se quatro épocas de semeadura da forrageira (0, 7, 14 e 21 dias após a semeadura do milho) e quatro doses do herbicida nicosulfuron (0, 4, 8 e 12 g ha -1 i.a.), sendo um experimento para cada nível de adubação, médio (300 kg ha -1 8-28-16) e alto (600 kg ha -1 8-28-16). Avaliou- se a produtividade de grãos, peso de mil grãos, altura de planta, altura de inserção da espiga, diâmetro do colmo do milho, prolificidade, biomassa da forrageira e cobertura vegetal do solo. Os resultados demonstraram que os componentes de produção do milho não apresentaram reduções significativas na presença de U. ruziziensis. No entanto, a semeadura tardia da U. ruziziensis reduziu o acúmulo de matéria seca da forrageira, assim como, a cobertura vegetal do solo. Do mesmo modo, a aplicação do herbicida nicosulfuron reduziu as características avaliadas da forrageira. O milho não apresenta redução da capacidade produtiva em convivência com U. ruziziensis. A ausência da aplicação do herbicida nicosulfuron e plantio simultâneo ao milho favorece maior acúmulo de biomassa e cobertura do solo de plantas de U. ruziziensis. O aumento da adubação promoveu maior rendimento do milho, no entanto, diminuiu o poder de competitividade da U. ruziziensis. / The integration of agriculture and livestock promotes the consortium and succession between these activities within the rural property. Broadcast seeding is a viable alternative to this system, however, there still is a lack of information about the time of sowing coupled with herbicide doses in order to delay the overgrowth of the forage, and how soil fertility influences this system.The objective of this work was to evaluate the yield components and agronomic characteristics of maize, and the soil cover promoted by the Urochloa ruziziensis plants in the corn intercropping system, by studying the sowing times and dosages of the herbicide nicosulfuron at different levels of fertilizing. Two experiments were conducted at the Experimental Station of Research and Extension of the Federal University of Viçosa, located in Coimbra, MG. A maize population of 70,000 ha -1 plants and the seeding density of 6 kg of ha -1 of U. ruziziensis were established. The experimental design was a randomized block design in a 4x4 factorial scheme, evaluating four forage sowing times (0, 7, 14 and 21 days after maize sowing) and four dosages of the herbicide nicosulfuron (0, 4, 8 e 12 g ha -1 i.a) for each level of fertilization, which were medium (300 kg ha -1 8-28-16) and high (600 kg ha -1 8-28-16). It was evaluated the grain yield, weight of a thousand grains, plant height, ear insertion height, corn stalk diameter, prolificity, number of kernel rows, number of grains by row, forage biomass and soil cover at 365 DAS and after the grazing simulation of U. ruziziensis. The results showed that maize production components did not show significant reductions in the presence of U. ruziziensis. However, late sowing of U. ruziziensis reduced the forage dry matter accumulation, as well as the reduction of soil cover. Likewise, the application of the herbicide nicosulfuron reduced the evaluated characteristics of the forage. Corn does not present a reduction of productive capacity in coexistence with U. ruziziensis. The absence of the application of the herbicide nicosulfuron and simultaneous planting to corn favors greater accumulation of biomass and soil cover of plants of U. ruziziensis. The increase in fertilization promoted higher maize yield, however, it decreased the competitive power of U. ruziziensis.

Les pesticides de nouvelle génération sont le plus souvent épandus à de faibles doses et en mélange. Peu d’études se sont intéressées jusqu’à présent à l’effet de ces mélanges sur la biodégradation et la toxicité de chaque pesticide et/ou métabolite. Le but de ces travaux de thèse était d’étudier les voies de biotransformation de chacun des trois herbicides d’un mélange constitué de mésotrione (β-tricétone), nicosulfuron (sulfonylurée) et S-métolachlore (chloroacétanilide) utilisé sur les cultures de maïs, ainsi que la toxicité (test Microtox ® ) des herbicides et de leurs métabolites, seuls et en mélanges. L’identification des métabolites de la mésotrione chez la souche Bacillus megaterium Mes11 et une étude de protéomique différentielle ont suggéré l’implication de nitroréductases dans la première étape de la biotransformation de cet herbicide, rôle confirmé ensuite par la caractérisation structurelle et fonctionnelle de deux enzymes capables de transformer la mésotrione : les nitroréductases NfrA1 et NfrA2, appartenant à la sous-famille NfsA-FRP des Nitro-FMN réductases. La voie de biotransformation du nicosulfuron a, quant à elle, été étudiée chez la souche Pseudomonas fluorescens SG-1 isolée à partir de sol agricole, capable de transformer cet herbicide par co-métabolisme. Cette biotransformation conduit à la formation de deux métabolites majoritaires issus du clivage de la liaison sulfonylurée du nicosulfuron, l’un deux (l’ADMP, 2-amino-4,6-diméthoxypyrimidine) présentant une toxicité 20 fois supérieure à celle de la molécule mère. Nous avons également étudié qualitativement et quantitativement la biotransformation de la mésotrione et du nicosulfuron par la souche Mes11 séparément ou en mélange, et en présence ou non de S-métolachlore Les résultats ont montré un effet négatif de la mésotrione sur la biotransformation du nicosulfuron et un effet positif du S-métolachlore sur la biotransformation de la mésotrione. Tous les mélanges d’herbicides testés ont montré des effets synergiques pour la toxicité vis-à-vis de A. fischeri, tandis que les mélanges de métabolites (avec ou sans S-métolachlore) étaient majoritairement synergiques ou antagonistes. La dernière partie des travaux de thèse est focalisée sur le développement d’une technique préventive de traitement de la pollution par les pesticides d’origine agricole (bioprophylaxie). Nous avons fait la preuve de concept de cette technique par une étude en microcosmes de sol. L’épandage simultané de l’herbicide 2,4-D (acide 2,4-dichlorophénoxyacétique) et de la souche Cupriavidus necator JMP134 capable de le minéraliser a en effet permis de réduire le temps de demi-vie de ce composé d’un facteur 3, tout en conservant son activité herbicide. / The new-generation pesticides are often sprayed at low dosages and in mixtures. Up to now, a few studies focused on the effect of these mixtures on the biodegradation and the toxicity of each pesticide and/or metabolite. The aim of this Ph.D. work was to study the biotransformation of each herbicide of a mixture composed of mesotrione (β-triketone), nicosulfuron (sulfonylurea) and S-metolachlor (chloroacetanilide) applied on maize crops, as well as the toxicity (Microtox® test) of the herbicides/metabolites alone or in mixture. The identification of mesotrione metabolites by the strain Bacillus megaterium Mes11 and a differential proteomic approach suggested the role of nitroreductases in the first step of mesotrione biotransformation. This was confirmed by the structural and functional characterization of two enzymes able to biotransform mesotrione: the NfrA1 and NfrA2 nitroreductases, belonging to the NfsA-FRP sub-family of Nitro-FMN reductases. The biotransformation pathway of nicosulfuron has been elucidated for the strain Pseudomonas fluorescens SG-1 isolated from an agricultural soil and able to co-metabolically biotransform nicosulfuron. Two major metabolites resulting from the cleavage of the sulfonylurea bridge were identified, one of them (ADMP, 2-amino-4,6-dimethoxypyrimidine) presenting a 20-fold higher toxicity than the parent compound. The simultaneous biotransformation of mesotrione and nicosulfuron by the strain Mes11 was also qualitatively and quantitatively studied, showing a negative effect of mesotrione on nicosulfuron biotransformation, and a positive effect of S-metolachlor on mesotrione biotransformation. All parent compound mixtures tested resulted in synergistic effects towards A. fischeri, while metabolite mixtures (with or without S-metolachlor) were mostly synergistic or antagonistic. The last part of the PhD work was devoted to the development of a preventive technique for the treatment of pollutions caused by agricultural pesticides (bioprophylaxis). We made the proof of concept of this method by using a soil microcosm study. The simultaneous spreading of 2,4-D (2,4-dichlorophenoxyacetic acid) herbicide and the strain Cupriavidus necator JMP134 able to mineralize it allowed a 3-fold reduction of 2,4-D half-life in soil, while preserving its herbicide activity.

In the summers of 1989 and 1990, researchers in Va. and Md. began to observe lateseason reductions in com vigor in areas treated with nicosulfuron or primisulfuron for postemergence johnsongrass control. Symptoms observed included chlorosis, reddening of the leaves and shortening of the internodes. The nature and time of symptom expression were consistent with those caused by maize chlorotic dwarfvirus (MCDV) and maize dwarf mosaic virus (MDMV) infection of com. It was hypothesized that postemergence johnsongrass control increased the incidence and severity of MCDV and MDMV in virus-susceptible corn hybrids due to increased feeding by vectors of these viruses on treated corn. Field experiments were conducted in 1991 and 1992 to evaluate the effect of postemergence johnsongrass control with broad casted nicosulfuron, postemergence directed imazethapyr, mechanical control and no control on virus disease incidence and severity in a virus-susceptible ('Southern States 565') and a virus-tolerant ('Southern States 844) corn hybrid. Visual injury evaluations taken 10 weeks after treatment showed that the virus-susceptible com hybrid sustained significantly more injury, averaged across johnsongrass control methods, than did the virus-tolerant corn hybrid. Within the virus-susceptible com hybrid, where johnsongrass was controlled, regardless of method, significantly more injury was observed relative to the nontreated check. Further, averaged across johnsongrass control treatments, the virus-tolerant corn hybrid yielded significantly higher compared to the virus-susceptible com hybrid. Experiments conducted in 1993 and 1994 utilized cages as a means of preventing insect movement from the infected johnsongrass to the crop. Blackfaced leafhopper evaluations suggested that the cages significantly reduced leafhopper movement from the infected johnsongrass to the corn, however complete exclusion was not achieved. Results of corn tissue assays showed that MCDV and MDMV were being transmitted, however no treatment differences were detected. Two experiments were conducted in 1994 to analytically test the hypothesis and to determine the time course of MCDV and MDMV double infection of corn tissue. Johnsongrass control treatments evaluated included broadcast nicosulfuron and no treatment. Postemergence johnsongrass control increased MCDV and MDMV incidence 9 to 21 days after treatment. Further, significantly more double infections of MCDV and MDMV were observed 14 to 21 days after treatment in experimental units receiving the nicosulfuron application. / Ph. D.

Repeated use of acetolactate synthase (ALS)-inhibiting herbicides in recent years has resulted in the selection of 89 weed species resistant to these herbicides. One management strategy that can eliminate or slow the development of resistance is applying mixtures of herbicides with different modes of action. This research involved the characterization of ALS-inhibiting herbicide-resistant smooth pigweed (<i>Amaranthus hybridus</i> L.), as well as investigations on weed management programs in corn (<i>Zea mays</i> L.) utilizing mesotrione, a triketone, in mixtures with other herbicides. ALS-inhibiting herbicide-resistant smooth pigweed biotypes were collected from fields in Virginia, Delaware, Maryland, and Pennsylvania to evaluate response to ALS-inhibiting herbicides and to determine the molecular mechanisms of resistance. Sequencing of the ALS genes from these biotypes revealed two amino acid substitutions known to confer resistance, Ala₁₂₂ to Thr and Ser₆₅₃ to Asn, and one that has not been previously reported in plants, Asp₃₇₆ to Glu. The smooth pigweed biotype with an Asp₃₇₆ substitution displayed resistance to four classes of ALS-inhibiting herbicides that included imidazolinone (IMI), sulfonylurea (SU), pyrimidinylthiobenzoate (PTB), and triazolopyrimidine sulfonanilide (TP) chemistries. Transformation of this smooth pigweed ALS gene into <i>Arabidopsis thaliana</i> confirmed that the Asp₃₇₆ substitution is responsible for the resistance. Other biotypes that had a substitution at Ala₁₂₂ exhibited resistance to an IMI herbicide, little to no resistance to SU herbicides, and increased sensitivity to a PTB and a TP herbicide, whereas, biotypes that had a substitution at Ser₆₅₃ exhibited high-level resistance to an IMI herbicide and lower resistance to PTB and SU herbicides. Experiments were also conducted to investigate the effectiveness of mesotrione in preemergence (PRE) and postemergence (POST) corn weed management programs in Virginia. Mesotrione applied PRE in mixtures with <i>S</i>-metolachlor and atrazine controlled common lambsquarters (<i>Chenopodium album</i> L.), smooth pigweed, common ragweed (<i>Ambrosia artemisiifolia</i> L.), and morningglory (<i>Ipomoea</i> spp.) species when a timely rainfall followed application. POST applications of mesotrione controlled common lambsquarters and smooth pigweed, but common ragweed and morningglory species were not always controlled. Common ragweed and morningglory species were controlled by mesotrione in a mixture with atrazine POST. Large crabgrass [<i>Digitaria sanguinalis</i> (L.) Scop.] and giant foxtail (<i>Setaria faberi</i> Herrm.) control was generally better when the ALS-inhibiting herbicides nicosulfuron plus rimsulfuron or rimsulfuron plus thifensulfuron plus atrazine were applied in a mixture with mesotrione. Mixtures of mesotrione with other POST herbicides in a total POST program produced corn yields comparable to standard PRE followed by POST weed management programs. / Ph. D.