993 resultados para postemergence herbicide


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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Stryphnodendron obovatum Benth. known as barbatimão de folha miúda, is a typical tree of the Midwest and Southeast “Cerrado” regions of Brazil. Several secondary metabolites have been identified in its barks, including tannins, described on the literature as allelochemicals. Beholding to identify a possible allelopathic activity in S. obovatum leaves, we tested hydroethanolic EtOH:H2 O (70% and 50% v/v) extracts, in different concentrations, on the initial development of cucumber (Cucumis sativus L.). Among the results, we highlight the effect of the 50% hydroethanolic extract in inhibiting the formation of the main and the secondary roots and the stimulation of the hypocotyl growth in C. sativus by the 70% hydroethanolic extract, both in all concentrations tested. The cytotoxic activity, evaluated by bioassay toxicity on Artemia salina Leach., was negative for the tested extracts (LC50> 1000 mg.mL-1). Concomitantly, the molluscicidal activity, evaluated against snails of Biomphalaria glabrata Say, presented low acute toxicity of solutions of 70% hydroethanolic extract at concentrations of 128.9 mg.mL-1 and 172.8 mg.mL-1 and values above 250 mg.mL-1 to solutions of 50% hydroalcoholic extract, being therefore considered inactive for these. The results suggest the existence of allelochemicals in the extracts tested and they have low toxicity.

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One of the major constraints to sustainable of the tillage is the rapid decomposition of dry the matter. One of the mechanisms known to facilitate this process is the interference in pathways of polymers of lignin from tests of application of low doses of herbicide based on the relation that higher the content of the lignin greater the resistance to degradation. With this purpose, the herbicide Verdict * R (haloxyfop-methyl) was used to verify the effect of low doses at the height of the plants, productivity of dry matter and in the metabolism of the lignin in plants of black oat. Preliminary tests in the greenhouse were realized for adjustments ​​to the best low doses to be applied in the definitive experiment in the production area. The results obtained were 24% of increase in productivity in the experiments conducted in greenhouse, from the application of 3.125g of the active ingredient of the haloxyfop-methyl per hectare, in this subdose no changes was observed in growth and content of lignin in plants of black oat. In the field, the concentration of 2.5g i. a. ha-1 of haloxyfop-methyl decreased in 9% the lignification rate without interfering with the height and productivity of the plants, this being favorable to the degradation rate of stubble tillage on outcome

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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Agronomia (Proteção de Plantas) - FCA

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Pós-graduação em Agronomia (Produção Vegetal) - FCAV

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Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV

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

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

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

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