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Background. The aim of this study was to investigate the possibility of using sodium selenite as a treatment for acute glyphosate poisoning using the activity of the lipid peroxidation and antioxidant defence systems as a readout for efficacy. Material and methods. Experimental glyphosate poisoning and subsequent treatment using sodium selenite was performed in albino rats (105). Glyphosate was given in doses of 50, 100 and 130 mg/kg, and sodium selenite was administered at a dose of 2 μg/kg. The blood concentrations of lipid peroxidation markers including conjugates of diene andtrienoic and malondialdehyde were determined. The endogenous glutathione (reduced form) level and activities of catalase, superoxide dismutase and glutathione peroxidase in the serum were measured. Results. Glyphosate poisoning has been found to result in a significant increase in lipid peroxidation activity. For example, malonic dialdehyde demonstrates a 2.35 times increase at a glyphosate dose of 130 mg/kg. At the experimental glyphosate poisoning dose of 100 mg/kg the measurements of superoxide dismutase and glutathione peroxidase have been found to decrease 1.58 and 2.21 times, respectively. At a dose of 130 mg/kg, those values decreased 2.51 and 4.76 times, respectively, compared to untreated controls. Conclusions. The use of sodium selenite at a dose of 2 μg/kg after poisoning of white rats with glyphosate (at doses of 50, 100 and 130 mg/kg) normalizes the lipid peroxidation and antioxidant defence activities of the body.
Field experiments were conducted to evaluate the efficacy of glyphosate (H1) and fluazifop-P-butyl (H2) herbicides with adjuvants on the common reed without cutting and at two different cutting levels (10 and 30 cm). The adjuvants were urea, nitric acid and sulfonic acid. The relative importance value (RIV), leaf chlorophyll content and plant density were determined to assay the efficacy of herbicides. Glyphosate treatment only (H1 a) was more effective than fluazifop-P-butyl (H2 a) on reeds without cutting and at the 10 cm cutting level. However, no significant difference was observed between them at the 30 cm cutting level. A positive effect of plant cutting occurred on the efficacy of all herbicides applied alone or in a tank mix with adjuvants. Furthermore, the 10 cm cutting level was more effective in eradication of reeds than the 30 cm cutting level. The adjuvants significantly improved the efficacy of the recommended (Hb) and half recommended (Hc) herbicide rates in comparison to being used alone on uncut reeds. The reduction percentages were 94.5, 86.99, 76.61 and 69.94 for H1 b, H1 c, H2 b and H2 c treatments, respectively. However, the adjuvants did not improve the glyphosate effect at different levels of cutting. Conversely the reduction percentage of reeds was improved by the recommended rate of fluazifop-P-butyl with adjuvants (H2 b) to 92.77% and 84.62% at 10 and 30 cm cutting levels, respectively.
Erosion processes can strongly influence the dissipation of glyphosate and aminomethylphosphonic acid applied with Roundup Max in agricultural soils; in addition, the soil structure state shortly before erosive precipitations fall can be a key parameter for the distribution of glyphosate and its metabolite. Field rain simulation experiments showed that severe erosion processes immediately after application of Roundup Max can lead to serious unexpected glyphosate loss even in soils with a high presumed adsorption like the Cambisols, if their structure is unfavourable. In one of the no-tillage-plot of the Cambisol, up to 47% of the applied glyphosate amount was dissipated with surface run-off. Moreover, at the Chernozem site with high erosion risk and lower adsorption potential, glyphosate could be found in collected percolation water transported far outside the 2x2 m experimental plots. Traces of glyphosate were found also outside the treated agricultural fields.
Broomrapes (Orobanche spp.) are important parasitic weeds of peas, faba bean and tomatoes and other winter crops in Egypt. They are widespread and are major factors limiting production of these crops. From an extensive survey of Egyptian soils naturally infested with broomrapes, 42 isolates of fungi belonging to genera of Alternaria, Fusarium and Trichoderma were identified as pathogens of broomrapes under laboratory and greenhouse conditions. Three isolates of Trichoderma spp. including T. harzianum T1, T. harzianum T3 and T. viride T2 were further tested for control of Orobanche spp. in peas, faba bean and tomatoes under field conditions. Results of field studies showed that soil treatment with these three fungal agents alone or soil treatment with fungal agents plus aerial spray of glyphosate (50 ppm) was effective in reducing infection of broomrapes and increasing yields of peas, faba bean and tomatoes. The prospect of developing T. harzianum T1, T. harzianum T3 and T. viride T2 as mycoherbicides for control of bromerapes of peas, faba bean and tomatoes in Egypt is discussed in this paper.
The aim of this study was to compare the physiological responses of six plant species (popular crops or plants recommended as indicators of soil pollution) to a wide range of glyphosate concentrations (0, 1, 3, 7, 10, 40, 80, 120, 180, 240, 400, 750, 1,000, 1,500, 1,700 and 2,000 μM). Percent germination, root length, seedling dry mass and myo-inositol content, as well as seedling leachate electroconductivity were determined in Lepidium sativum, Sinapis alba, Sorghum saccharatum, Brassica napus, Lupinus luteus and Avena sativa. Percent seed germination, seedling dry mass and electroconductivity of seedling leachates were not clearly affected by the herbicide and could not be used as indicators of its phytotoxicity. An metabolite induced by abiotic stresses in many plants, myo-Inositol, was very strongly stimulated by glyphosate at doses above 10 or 40 μM, depending on plant species. The sensitivity of analyzed plants to glyphosate, as manifested by root length, differed clearly. In Avena sativa the relationship between root length and glyphosate concentration was fairly linear over a wide range of herbicide doses (up to 240-400 μM). The most distinct drop in root growth at low herbicide doses was visible in Sorghum saccharatum. The results show that a mild stress affecting root length may not clearly modify seedling myo-inositol levels, that respond distinctly to stronger stresses. Not all indicator plants are equally suitable for analysis of biological activity of glyphosate residues. Sorghum saccharatum seems particularly sensitive.
This study was aimed at evaluating the effect of sublethal doses of glyphosate on physiological parameters of a common ornamental plant Mexican marigold (Tagetes erecta). The herbicide was applied in the following doses: 720 g ⋅ ha–1 (standard field dose), 144 g ⋅ ha–1, 28.8 g ⋅ ha–1, and 14.4 g ⋅ ha–1, in the form of a spraying treatment of plants in a specialist spraying chamber. The net assimilation rate and leaf greenness index were then determined. Herbicide application in the sublethal doses, i.e. below 720 g ⋅ ha–1, caused disorders in both analyzed physiological parameters of plants. The glyphosate dose of 144 g ⋅ ha–1 elicited transient disorders in the leaf greenness index. In turn, the use of the lower doses (28.8 g ⋅ ha–1 and 14.4 g ⋅ ha–1) caused a short-term increase in the net photosynthesis rate in the plants which was accompanied by a decreased value of the leaf greenness index. Study results demonstrated the effect of sublethal doses of glyphosate as a stress factor in parameters associated with the process of photosynthesis in plants.
Efficient weed management is essential for avoiding competition for water, light, and nutrient resources in semiarid zones. Chemical weed control with glyphosate was evaluated on perennial wall-rocket (Diplotaxis tenuifolia), artichoke thistle (Cynara cardunculus), slender wild oat (Avena barbata), and perennial ryegrass (Lolium perenne). Plants at early, middle and advanced vegetative stages were used in this study. Glyphosate potassium salt was applied at rates of 0.0675 (1/16x), 0.135 (1/8x), 0.27 (1/4x), 0.54 (1/2x), 1.08 (x) and 2.16 (2x) kg acid equivalent (ae) ⋅ ha–1. Glyphosate combined with 2,4-D amine salt was evaluated at rates of 1.08 kg ae ⋅ ha–1 and 0.53 kg active ingredient (ai) ⋅ ha–1, respectively. The volume of the spray was 100 l ⋅ ha–1 with 86 droplets ⋅ cm–2 and a Volume Median Diameter (VMD) of 421.19 μm. In general, all the tested weeds were controlled with a quarter of the label rate. Three sizes of tested plants were controlled in a similar way at the same glyphosate dose rate. Moreover, the addition of 2,4-D to glyphosate did not produce an increase in the control of broadleaf weeds. The results showed that glyphosate was effective in controlling the tested weed species, including low application rates for all the growth stages in the southwestern Buenos Aires province.
In 2007–2008 field experiments were conducted to estimate the biological activity of glyphosate (Roundup 360 SL) against Agropyron repens and broad-leaved weed species on stubble and barren land. The herbicide was applied with some additives (Superzwilżacz, water glass) and water conditioner adjuvants (X-Change, Niagara, ammonium sulfate, AS 500 SL) at two spray volumes 130 and 260 l/ha, respectively. For treatments different spray quality (water distilled, standard tap water – 13,4°n, hard water – 33,4°n) was used. The best results were obtained when glyphosate with addition of ammonium sulfate or AS 500 SL was applied, regardless of water quality used for the dilution of herbicide. Effect on weeds was better when herbicide was applied with hard water. The addition of water conditioner, especially X-Change increased glyphosate activity against A. repens and other weed species. The efficiency of glyphosate against weeds was higher with the use of the lower spray volume 130 l/ha comparing to the treatments with spray volume of 260 l/ha.
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