Dinâmica e eficácia do herbicida dicamba quando aplicado no sistema solo e palha
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Data
2021-02-25
Autores
Mundt, Tamara Thaís
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Universidade Estadual Paulista (Unesp)
Resumo
Uma parte de toda aplicação de produto fitossanitário utilizado na agricultura tem como destino final o solo. Com relação a herbicidas, diversos fatores podem influenciar na dinâmica do produto no ambiente e disponibilidade para o controle de plantas daninhas. O dicamba é um herbicida utilizado na dessecação pré-semeadura e para controle em pós-emergência de plantas daninhas de folha larga. Desta forma, o objetivo deste estudo foi avaliar a dinâmica do dicamba aplicado no solo e na palha. Os ensaios foram realizados em Botucatu – SP (solo argiloso), Santa Cruz das Palmeiras – SP (solo argiloso), Luís Eduardo Magalhães – BA (solo arenoso) e em casa de vegetação. Foram aplicadas 4 doses do herbicida (120, 240, 480 e 720 g e. a.) sobre o solo, sobre o solo e posterior colocação da palha de milho e sobre a palha, além de testemunhas com e sem palha, em blocos casualizados (campo) e delineamento inteiramente casualizados (casa de vegetação), com 4 repetições cada. As aplicações em campo foram realizadas com pulverizador costal pressurizado a CO2, equipado com barra de 6 pontas de jato plano da série Teejet TTI 110 015. Foram realizadas coletas de solo na profundidade de 0-10 cm 1 dia após a aplicação nas 3 cidades, e 6, 11 e 30 dias após a aplicação em Botucatu (0-10 cm, 10-20 cm e 20-40 cm), e 4, 15 e 30 DAA em Santa Cruz das Palmeiras e Luís Eduardo Magalhães (0-10 cm, 10-20 cm e 20-40 cm) que posteriormente foram levadas para análises cromatográficas no laboratório NUPAM-FCA/Unesp. As aplicações dos experimentos em casa de vegetação foram realizadas em simulador de pulverização, equipado com barra de 4 pontas de jato plano da série Teejet tipo TTI 110.015. Em todos os experimentos foram realizadas avaliações de controle das plantas daninhas, e nos experimentos de Botucatu, Santa Cruz das Palmeiras e casa de vegetação, realizou-se também a densidade populacional de plantas. Nas 3 localidades estudadas as concentrações de dicamba encontradas foram superiores nos tratamentos aplicados sobre o solo sem a adição da palha. Botucatu apresentou as menores concentrações do herbicida, possivelmente devido as precipitações ocorridas durante o desenvolvimento do experimento. O solo de Luís Eduardo Magalhães apresentou as maiores quantidades de herbicida em todos os períodos, fato este que pode estar relacionado com uma menor quantidade de matéria orgânica e consequentemente menor degradação do herbicida. Ainda, apresentou maiores concentrações nas camadas superficiais que pode ser explicado pela baixa concentração pluviométrica naquela região durante o experimento. O controle de plantas daninhas apresentou baixos índices no experimento realizado em campo em Botucatu, seguido de Santa Cruz das Palmeiras, e Luís Eduardo Magalhães obtendo os melhores índices de controle, que está relacionado com uma maior quantidade da molécula herbicida encontrada no solo. O controle de plantas daninhas em casa de vegetação foi eficiente e ainda apresentou altos níveis de controle das plantas de soja e algodão, principalmente nas maiores doses estudadas, além de diminuição acentuada na densidade de plantas com a soja mostrando-se mais sensível que o algodão. A densidade populacional de plantas daninhas foi diminuída em todos os experimentos realizados.
A portion of every phytosanitary application used in agriculture has the soil as a final destination. Regarding to herbicides, several factor can influence the dynamics of the product in the environment and availability for weed control. Dicamba is a herbicide used in pre-plant and post-emergence to control broadleaf weeds. Thus, the objective of this study was to evaluate the dynamics of dicamba applied to the soil and straw. The experiments were carried out in Botucatu – SP (clay soil), Santa Cruz das Palmeiras – SP (clay soil), Luís Eduardo Magalhães – BA (sandy soil) and in greenhouse. Four doses of the herbicide (120, 240, 480 e 720 g e.a.) were applied on the soil, on the soil and subsequent placement of the corn straw and on the straw, and controls with and without straw, in randomized blocks (field) and completely randomized design (greenhouse), with 4 replications each. Field applications were carried out with a CO2 pressurized back sprayer, equipped with 6 flat jet nozzles (TTI 110 015). Soil were performed at a depth of 0-10 cm 1 day after application in all 3 cities and 6, 11 and 30 days after application in Botucatu (0-10 cm, 10-20 cm e 20-40 cm), and 4, 15 and 30 DAA in Santa Cruz das Palmeiras and Luís Eduardo Magalhães (0-10 cm, 10-20 cm and 20-40 cm) that were taken tp chromatographic analysis at NUPAM - FCA/Unesp. The applications of greenhouse experiments were carried out in a spray simulator, equipped with 4 flat jet nozzles (TTI 110 015). In all experiments were carried out evaluations of weed control, and in Botucatu, Santa Cruz das Palmeiras and greenhouse experiments plant population density were evaluated. In the 3 locations studied, the dicamba concentrations found were higher in the treatments applied on the soil without the addition of straw. Botucatu presented the lowest concentrations of the herbicide, possibly due to the precipitation that occurred during the development of the experiment. Luís Eduardo Magalhães’ soil presented the highest amounts of herbicide in all periods, a fact that may be related to less organic matter and consequently less degradation. Still, it presented higher concentrations in the superficial layers that can be explained by the low pluviometric concentration in that region during the experiment. Weed control showed low rates in Botucatu field experiment, followed by Santa Cruz das Palmeiras and Luís Eduardo Magalhães obtaining the best control rates, which is related to a greater amount of the herbicide molecule found in the soil. The control of weeds in the greenhouse was efficient and present high levels of phytointoxication of soybean and cotton plants, mainly in the highest doses studied, in addition to a marked decrease in plant density with soybean being more sensitive than cotton. The population density of weeds were reduced in all experiments carried out.
A portion of every phytosanitary application used in agriculture has the soil as a final destination. Regarding to herbicides, several factor can influence the dynamics of the product in the environment and availability for weed control. Dicamba is a herbicide used in pre-plant and post-emergence to control broadleaf weeds. Thus, the objective of this study was to evaluate the dynamics of dicamba applied to the soil and straw. The experiments were carried out in Botucatu – SP (clay soil), Santa Cruz das Palmeiras – SP (clay soil), Luís Eduardo Magalhães – BA (sandy soil) and in greenhouse. Four doses of the herbicide (120, 240, 480 e 720 g e.a.) were applied on the soil, on the soil and subsequent placement of the corn straw and on the straw, and controls with and without straw, in randomized blocks (field) and completely randomized design (greenhouse), with 4 replications each. Field applications were carried out with a CO2 pressurized back sprayer, equipped with 6 flat jet nozzles (TTI 110 015). Soil were performed at a depth of 0-10 cm 1 day after application in all 3 cities and 6, 11 and 30 days after application in Botucatu (0-10 cm, 10-20 cm e 20-40 cm), and 4, 15 and 30 DAA in Santa Cruz das Palmeiras and Luís Eduardo Magalhães (0-10 cm, 10-20 cm and 20-40 cm) that were taken tp chromatographic analysis at NUPAM - FCA/Unesp. The applications of greenhouse experiments were carried out in a spray simulator, equipped with 4 flat jet nozzles (TTI 110 015). In all experiments were carried out evaluations of weed control, and in Botucatu, Santa Cruz das Palmeiras and greenhouse experiments plant population density were evaluated. In the 3 locations studied, the dicamba concentrations found were higher in the treatments applied on the soil without the addition of straw. Botucatu presented the lowest concentrations of the herbicide, possibly due to the precipitation that occurred during the development of the experiment. Luís Eduardo Magalhães’ soil presented the highest amounts of herbicide in all periods, a fact that may be related to less organic matter and consequently less degradation. Still, it presented higher concentrations in the superficial layers that can be explained by the low pluviometric concentration in that region during the experiment. Weed control showed low rates in Botucatu field experiment, followed by Santa Cruz das Palmeiras and Luís Eduardo Magalhães obtaining the best control rates, which is related to a greater amount of the herbicide molecule found in the soil. The control of weeds in the greenhouse was efficient and present high levels of phytointoxication of soybean and cotton plants, mainly in the highest doses studied, in addition to a marked decrease in plant density with soybean being more sensitive than cotton. The population density of weeds were reduced in all experiments carried out.
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Palavras-chave
Mimetizadores de auxinas, Cromatografia, Controle de plantas daninhas, Glycine max (L.), Gossypium hirsutum, Auxin mimics, Chromatogrophy, Weed control