Controle químico de Panicum repens e Paspalum repens

Panicum repens e Paspalum repens são espécies infestantes de ambientes úmidos e alagados, freqüentes em margens de lagos, reservatórios, canais de irrigação e drenagem. O presente trabalho teve como objetivo avaliar a eficiência de diferentes herbicidas no controle dessas duas espécies. O experimento foi conduzido no Núcleo de Pesquisas Avançadas em Matologia, do Departamento de Produção Vegetal, pertencente à Faculdade de Ciências Agronômicas/UNESP, campus de Botucatu-SP. As plantas foram cultivadas em caixas d'água e as pulverizações foram realizadas utilizando-se um pulverizador costal pressurizado a CO2. Os tratamentos testados foram: glyphosate a 2.400, 3.360 e 4.320 g e.a. ha-1 + Aterbane 0,5% v/v, glyphosate a 2.400, 3.360 e 4.320 g e.a. ha-1 + Silwet 0.1% v/v, imazapyr a 750 e 1.500 g e.a. ha-1 e diquat a 400 e 800 g i.a. ha-1 (em aplicações seqüenciais de 200+200 g i.a. ha-1 e 400+400 g i.a. ha-1), além de uma testemunha sem aplicação de herbicidas. O delineamento experimental utilizado foi inteiramente casualizado, com quatro repetições. Avaliações visuais de controle foram realizadas, sendo a massa seca das plantas determinada ao final do estudo. O herbicida glyphosate na dose de 4.320 g e.a. ha-1, independentemente do adjuvante utilizado, assim como na dose de 3.360 g e.a. ha-1 com Aterbane, proporcionou bom controle de Panicum repens e, em todas as doses e adjuvantes testados, promoveu controle excelente de Paspalum repens. O herbicida imazapyr, independentemente da dose testada, apresentou resultados insatisfatórios no controle das plantas de Panicum repens, porém promoveu um excelente controle de Paspalum repens; o herbicida diquat, apesar das duas aplicações e independentemente da dose utilizada, mostrou-se ineficiente para controle das duas espécies.

Potential effects of the herbicide Diuron on mammary and urinary bladder two-stage carcinogenesis in a female Swiss mouse model

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Toxicity of trifluralin herbicide in a representative of the edaphic fauna: Histopathology of the midgut of Rhinocricus padbergi (Diplopoda)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Surface morphology of Diplodon expansus (Kuster, 1856; Mollusca, Bivalvia, Hyriidae) gill filaments after exposure to environmentally relevant concentrations of atrazine herbicide

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Photo-Fenton degradation of the herbicide tebuthiuron under solar irradiation: Iron complexation and initial intermediates

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação de tratamentos químicos e mecânicos no controle de plantas daninhas na cultura do algodão

O presente trabalho teve como objetivo avaliar a eficiência de diferentes combinações de tratamentos herbicidas integrado, aplicados em PPI, pré, pós, cultivo mecânico e jato dirigido em cultura de algodão (Gossypium hirsutum L.). O experimento foi conduzido em campo, sendo a área experimental instalada na cultura de algodão cultivar IAC-20. Foram testados tratamentos com os seguintes produtos: trifluralina na dose de 1,068 kg i.a./ha; alachlor na dose de 1,584 kg i.a./ha; M.S.M.A. nas doses de 1,44 e 1,68 kg i.a./ha; nicosulfuron nas doses de 0,0201; 0,030 e 0,040 kg i.a./ha; diuron nas doses de 1,0 e 1,5 kg i.a./ha; lactofen na dose de 0,18 kg i.a./ha; cyanazine nas doses de 1,0 e 1,5 kg i.a./ha e diuron nas doses de 1,0 e 1,5 kg i.a./ha.Os tratamentos herbicidas foram efetuados em pré-plantio incorporado (PPI), pré-emergência (PRE), pós-emergência (POS), cultivo mecânico (CM) e jato dirigido (JD). Os resultados obtidos levaram a concluir que o sistema de trifluralina (PPI), alachlor (PRE), CM, M.S.M.A. + lactofen apresentaram a maior produtividade. Os sistemas herbicidas compostos por aplicação de trifluralina (PPI), alachlor (PRE), M.S.M.A. (POS), CM ao redor dos 50 a 60 D.A.P. (dias após o plantio) e a aplicação de jato dirigido de diuron, lactofen + cyanazine, lactofen + diuron, M.S.M.A. + cyanazine, M.S.M.A. + lactofen e M.S.M.A. + diuron, propiciaram de forma geral controle das principais plantas daninhas.

Degradation of the herbicide tebuthiuron using solar photo-Fenton process and ferric citrate complex at circumneutral pH

The influence of pH on the degradation of the herbicide tebuthiuron (TBH) was investigated using in situ generated Fe(III)-citrate complexes (Fe:cit) submitted to the photo-Fenton process under solar irradiation. Using Fe:cit in a wide pH range (2.5-7.5), 100-78% TBH oxidation was achieved respectively from a UV dose of 2.0 J cm(-2) (15 min). Moreover, the oxidation of TBH obtained in the presence of Fe:cit at pH 6.0 was higher than that obtained using Fe(NO3)3 at pH 2.5. A similar behavior is observed for the removal of total organic carbon (TOC) in TBH solutions. In the presence of Fe:cit, 20% and 85% of TOC was removed at pH 7.5 and 2.5, respectively, after 7.5 J cm-2 irradiation, while no mineralization was observed employing Fe(NO3)(3) for the same UV dose. Using Fe(NO3)(3), mineralization was observed only after 11 J cm-2 (8%). A higher mineralization rate was obtained with Fe(NO3)(3) only when a concentration three times higher was employed at pH 2.5. Besides the high efficiency of TBH degradation observed using the ferric citrate complex in the solar photo-Fenton process, it also offers the advantage of application at a pH of up to 7.5. (c) 2007 Elsevier B.V. All rights reserved.

Mechanism of micronuclei formation in polyploidizated cells of Allium cepa exposed to trifluralin herbicide

The trifluralin is an agent that promotes a cellular damage due to its direct action on the microtubules. This action leads to a decontrol in the cellular division, bringing about polyploid cells. In this work, we show the evidences that the exceeding genetical material of theses polyploidizated cells tends to be eliminated from the nucleus in the form of micronucleus. Our analyses prove this fact, both by the presence of a number of cells carrying micronucleus, and by the evidences of the elimination of the exceeding material itself, after exposition of the Allium cepa root tips tested with several concentration of trifluralin herbicide. It was noticed that the residual concentration induced a number of polyploid cells, micronuclei and mini cells. Inferences about the implications of the elimination of genetic material from micronuclei, such as cell viability and apoptosis, are also presented. (c) 2007 Elsevier B.V. All rights reserved.

Origin of nuclear and chromosomal alterations derived from the action of an aneugenic agent-Trifluralin herbicide

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Chlorophyll fluorescence as a marker for herbicide mechanisms of action

Photosynthesis is the single most important source of 02 and organic chemical energy necessary to support all non-autotrophic life forms. Plants compartmentalize this elaborate biochemical process within chloroplasts in order to safely harness the power of solar energy and convert it into usable chemical units. Stresses (biotic or abiotic) that challenge the integrity of the plant cell are likely to affect photosynthesis and alter chlorophyll fluorescence. A simple three-step assay was developed to test selected herbicides representative of the known herbicide mechanisms of action and a number of natural phytotoxins to determine their effect on photosynthesis as measured by chlorophyll fluorescence. The most active compounds were those interacting directly with photosynthesis (inhibitors of photosystem I and II), those inhibiting carotenoid synthesis, and those with mechanisms of action generating reactive oxygen species and lipid peroxidation (uncouplers and inhibitors of protoporphyrinogen oxidase). Other active compounds targeted lipids (very-long-chain fatty acid synthase and removal of cuticular waxes). Therefore, induced chlorophyll fluorescence is a good biomarker to help identify certain herbicide modes of action and their dependence on light for bioactivity. Published by Elsevier B.V.

Use of Biopolymeric Membranes for Adsorption of Paraquat Herbicide from Water

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Poly(hydroxybutyrate-co-hydroxyvalerate) microspheres loaded with atrazine herbicide: screening of conditions for preparation, physico-chemical characterization, and in vitro release studies

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Acute exposure of a glyphosate-based herbicide affects the gills and liver of the Neotropical fish, Piaractus mesopotamicus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)