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[en] The objective of this study was evaluate the interacting effects on absorption and translocation of 14C-mesotrione and 14C-atrazine mixture for morning glory (Ipomoea hederifolia) control. The mixture of atrazine + mesotrione was shown to be additive and synergistic by visual assessment in relation to expected control, depending on the dose and evaluation period. Absorption of 14C-atrazine alone (62.5%) and as a mixture (60%) in morning glory was higher than in the treatments with 14C-mesotrione alone (42.8%) and as a mixture (46.6%). However, 14C-mesotrione alone showed a higher translocation (8.6%) than 14C-mesotrione + atrazine (2.5%), indicating that the mixture decreased the translocation of this herbicide. (author)
[en] A spectrofluorometric method for the determination of bentazone residues has been developed. The method is performed in N,N-dimethyl-formamide as solvent. The results were compared with those obtained by incorporation of the compound in α-cyclodextrin and liquid chromatography with spectrophotometric detection at 340 nm. The fluorescence intensity is linearly related to bentazone concentration with a detection limit of 3.3 ng ml-1 and a relative standard deviation of 1% at the 0.55 μg ml-1 level. The method was applied to herbicide added (0.2 μg ml-1) to beans with recoveries of 100.8% compared with 96% by the liquid chromatographic method. (author). 23 refs.; 4 figs.; 2 tabs
[en] Mineralisation of atrazine in soil has been shown to depend on previous exposure of the herbicide. In this study, 24 Danish soils were collected and screened for potential to mineralise atrazine. Six soils were chosen, because they had never been exposed to atrazine, whereas 18 soils were chosen because of their history of application of atrazine or the related compound terbuthylazine. None of the 24 soils revealed a mineralisation potential of more than 4% of the added atrazine within a 60 day timeframe. In an atrazine adapted French soil, we found 60% mineralisation of atrazine in 30 days. Cattle manure was applied in order to boost the microbial activity, and a 2-3% increase in the atrazine mineralisation was found in some of the temperate soils, while in the highly adapted French soil it caused a 5% reduction. - The study highlights that pre-exposure of soils to triazine herbicides do not result in rapid mineralization in temperate soils.
[en] The ability of melatonin as a protective and detoxifying agent against paraquat-induced oxidative damage in rat lungs and liver was examined. Changes in reduced glutathione (OSH) concentration and malonaldehyde (MDA) level were measured. Pathological examination to lungs and liver was done. Paraquat in 2 doses (20,70 mg/kg) was injected I.P. into rats with melatonin (10 mg/kg) I. P. either before and after paraquat intoxication or only after it. Melatonin proved its protective role when given before and after paraquat intoxication more than its detoxifying effect when given only after paraquat. The biochemical improvement following melatonin therapy was more evident than the histopathological one. (author)
[en] Several herbicide-tolerant crops have been developed and commercialized from herbicide-tolerant mutants obtained through chemical mutagenesis followed by herbicide selection or direct herbicide selection of spontaneous mutations. All mutations used in commercial herbicide-tolerant crops are derived from a single nucleotide substitution of genes that encode enzymes or proteins targeted by herbicides. The alleles of all commercial herbicide-tolerant mutations are incompletely-dominant except for the triazine-tolerant mutation. (author)
[en] This study evaluates the effects of the triazine herbicide simazine in an outdoor pond microcosm test system that contained two submerged rooted species (Myriophyllum spicatum and Elodea canadensis) and two emergent rooted species (Persicaria amphibia and Glyceria maxima) over a period of 84 days. Simazine was applied to the microcosms at nominal concentrations of 0.05, 0.5 and 5 mg/L. General biological endpoints and physiological endpoints were used to evaluate herbicide toxicity on macrophytes and the algae developing naturally in the system. Concentration-related responses of macrophytes and algae were obtained for the endpoints selected, resulting in a no observed ecologically adverse effect concentration (NOEAEC) at simazine concentrations of 0.05 mg active ingredient/L after 84 days. E. canadensis was the most negatively affected species based on length increase, which was consistently a very sensitive parameter for all macrophytes. The experimental design presented might constitute a suitable alternative to conventional laboratory single-species testing. - Simazine at concentrations of 0.05 mg/L does not cause long-term negative effects to aquatic macrophytes or algae.
[en] Glyphosate-based herbicides (GBH) are the most used herbicides worldwide and are considered as endocrine-disrupting compounds (EDC) for non-target organisms. However, effects of GBH on their endocrine systems remain poorly understood. Thus, the aim of this study was to assess the effects of low concentrations of Roundup WG® on growth and reproduction process molecules in both males and females of the decapod crustacean Macrobrachium potiuna, by the relative transcript expression levels of the ecdysteroid receptor (EcR), the molt-inhibiting hormone (MIH), and the vitellogenin (Vg) genes. Prawns were exposed to three concentrations of GBH (0.0065, 0.065, and 0.28 mg L−1) for 7 and 14 days. The results revealed that only in males the three genes transcript levels were influenced by the GBH concentration, time of exposure, and the interaction between the concentrations and time of exposure, suggesting that males were more sensitive to GBH than females. For males, after 7 days of exposure at 0.065 mg L−1, EcR and MIH were over-expressed, while the Vg expression was only over-expressed after 14 days. The present study highlighted that GBH impacted endocrine systems of M. potiuna. Moreover, EcR and MIH gene expressions could be promising EDC biomarkers of exposure in crustaceans. These results also indicate that GBH concentrations, considered secure by regulatory agencies, should be reviewed to minimize the effects on non-target organisms. .
[en] Greenhouse and field studies allow advice to be given about improving application procedures and for a herbicide. - Persistence, stability, mobility and activity characteristics of organoclay and commercial formulation of alachlor were evaluated in soil columns and field plots in Gaza, Palestine. Relative concentrations of alachlor were accumulated in the top soil as determined by bioassay and consequently its mobility was retarded in soil treated with organoclay formulation. Alachlor applied as commercial EC formulation readily distributed through the soil media to a deeper depth. The herbicidal activity of alachlor applied as organoclay formulation was limited to the top soil whereas it disappeared from the top soil in plots treated with EC commercial formulation. Greenhouse and field experiments showed persistence, reduced mobility, safe and effective herbicide formulation at a significantly reduced applied rate when alachlor was applied as organoclay formulation