Addition Of Glyphosate Research Articles

Determination of enzymatic activity of 5-enolpyruvylshikimate-3-phosphate synthase by LC/MS.

A liquid chromatography-mass spectrometry (LC/MS) method for determining the enzymatic activity of 5-enolpyruvylshikimate-3-phosphate synthase (EPSP synthase), an enzyme of the shikimate pathway, was developed. EPSP synthase catalyzes the formation of 5-enolpyruvylshikimate-3-phosphate (EPSP) from shikimate-3-phosphate (S-3-P) and phosphoenolpyruvate (PEP) in microorganisms and plants. The enzymatic activity of EPSP synthase was assessed by the determination of EPSP after a 30-min incubation with S-3-P and PEP using the LC/MS system. EPSP synthase activity is given in terms of the produced EPSP (pmol/min/mg protein). Glyphosate (N-phosphonomethyl glycine)-tolerant EPSP synthase from the Agrobacterium sp. strain CP4 (CP4-EPSP synthase) in genetically modified soybeans (GM-soybeans) was found to have an enzymatic activity of 736 EPSP pmol/min/mg protein in the presence of 3 nmol of S-3-P. In contrast, the enzyme activity of non-GM-soybeans was 21 EPSP pmol/min/mg protein. The EPSP synthase activity was markedly decreased in the non-GM-soybeans by the addition of glyphosate, but the enzyme activity of the GM-soybeans was only slightly decreased with this treatment. This LC/MS system could also be applicable to the measurement of EPSP synthase activity in different plant species and the detection of herbicide-tolerant EPSP synthase in GM foods.

Pesticide influence on soil enzymatic activities

The influence of four pesticides, e.g. glyphosate, paraquat, atrazine, and carbaryl, on the activities of invertase, urease and phosphatase of twenty-two soils, numbered as 1–22, was investigated. Soils displayed a general variability of enzyme activities with invertase being more abundant than urease and phosphatase in the order listed. The addition of glyphosate and paraquat activated invertase and urease activities in several soils. Increments of invertase activity ranged from a very low increase (+4%) up to +204% in soils 11 and 14, respectively. Smaller increases were measured for urease. A general inhibitory effect (from 5% to 98%) was observed for phosphatase in the presence of glyphosate. The effects of atrazine and carbaryl on the three soil enzymes were evaluated against that exhibited by methanol, the solvent used for their solubilization. In almost all soils, atrazine further inhibited invertase activity with respect to the inhibitory effect shown by methanol. By contrast, consistent activation effects (from 61% to 10217%) were measured for urease with methanol alone and/or methanol-pesticide mixtures. Contradictory results were observed with phosphatase. Similarities found between the results obtained with enzymes in soils and those measured with synthetic enzyme complexes (e.g. free enzymes and/or clay–, organo–, and organo–clay–enzyme complexes) exposed to the same pesticides allowed some relationships between responses of soil enzymes to pesticides and soil properties to be hypothesized.

Weed Control from Herbicide Combinations with Three Formulations of Glyphosate1

Abstract: Greenhouse studies were conducted to evaluate weed control from various formulations of glyphosate alone and in combination with postemergence herbicides. Tank mixtures did not increase barnyardgrass control 2 wk after treatment (WAT) when compared with glyphosate alone; however, tank mixtures did reduce barnyardgrass fresh weight 4 WAT when compared with glyphosate alone in several instances. Antagonism was observed when chlorimuron was combined with all formulations of glyphosate 4 WAT, but control was not reduced when compared with glyphosate alone. Selective herbicides added to glyphosate had an additive or antagonistic effect on prickly sida fresh-weight reductions. Antagonism of pitted morningglory fresh-weight reductions occurred when glyphosate was combined with all herbicides except acifluorfen, which had an additive effect. Fomesafen or lactofen effectively controlled hemp sesbania 2 WAT without the addition of glyphosate. Acifluorfen and chlorimuron combined with glyphosate Cheminova,...

Interaction of Glyphosate and 2,4-DB for the Control of Selected Morningglory (Ipomoeaspp.) Species

Interaction of glyphosate and 2,4-DB was evaluated in greenhouse and laboratory studies with respect to control of four species of annual morningglory. The greenhouse study included smallflower, pitted, palmleaf, and ivyleaf morningglory at three growth stages: seedling, juvenile, and vining. A series of glyphosate rates (0.28 to 1.26 kg ae/ha) and 2,4-DB (0.022 and 0.045 kg ae/ha) were applied alone, and in all possible two-way tank mixtures. Morningglory response to both glyphosate and 2,4-DB applied alone was species- and growth stage-dependent. All combinations were either additive or synergistic for control of pitted, palmleaf, and ivyleaf morningglory. Response of smallflower morningglory ranged from antagonistic to synergistic. Absorption and translocation of14C-2,4-DB was independent of the addition of glyphosate in all four species. By contrast, absorption of foliar-applied14C-glyphosate and translocation of14C from treated leaves to other plant parts were enhanced by the addition of 2,4-DB in all species except palmleaf morningglory. In palmleaf morningglory,14C-glyphosate absorption and translocation were independent of the addition of 2,4-DB. Absorption and translocation data were in agreement with greenhouse studies.

Foliar uptake of organosilicone surfactant oligomers into bean leaf in the presence and absence of glyphosate

AbstractThe nonionic organosilicone surfactant ‚Silwet’︁® L‐77TM (1, 2 and 5 g litre−1) and [14C]glyphosate‐monoisopropylammonium (10 g litre−1 a.e.), were applied, alone and in combination with each other, to the upper surfaces of leaves of Vicia faba L. plants growing in a controlled environment. Over 80% of the glyphosate was taken up within 10 min in the presence of 5 g litre−1 L‐77, with no further uptake over the remaining period. A similar pattern of uptake was observed with 2 g litre−1 L‐77, but only 30% was taken up initially. In the presence of 1 g litre−1 L‐77 initial glyphosate uptake was only 15%, but uptake continued, subsequently reaching c.25% after 360 min, this behaviour being essentially the same as that of glyphosate when applied without surfactant. The uptake of L‐77 was not significantly affected by the addition of glyphosate, being c.80% within 10 min at 5 g litre−1, but with a slow, further increase of c.12%. At 2 g litre−1 uptake was c.45% within 10 min, rising to c.70% by 360 min. The 1 g litre−1 solutions showed a similar pattern, with uptake increasing from c.35% at 10 min to over 60% after 360 min. In the absence of glyphosate, individual L‐77 oligomers penetrated at similar rates. In the presence of glyphosate, however, some discrimination was evident among the oligomers, in particular when the surfactant was added at 1 g litre−1. Literature on the foliar uptake of surfactants is reviewed and discussed in relation to the results of this study.

Specificity of Glyphosate Action in Candida maltosa

Summary We used Candida maltosa for comparative studies on the mode of action of glyphosate and of 9 structural variations (glyphosine, phosphonoalanine, aminomethylphosphonic acid, S 49, S 71 K, S 96, E98, E 120, M 1) of the glyphosate molecule. In the presence of 50mM glyphosate, glyphosine, S 71 K, and S 96 a total inhibition of growth of the yeast could be observed. Only the glyphosate induced growth inhibition was completely reversed by the aromatic amino acids. The addition of glyphosate caused an intracellular accumulation of shikimate and shikimate-3-phosphate and a reduction of aromatic amino acids. We examined the influence of the phosphono derivatives on the activity of 3 enzymes of the shikimate pathway tyrosine-sensitive 3-deoxy-D- arabino -heptulosonate-7-phosphate synthase, dehydroquinate synthase, 5- enol pyruvylshikimate-3-phosphate synthase). Only glyphosate caused a stringent inhibition of the enzymes. Other related compounds produced little or no inhibition. C. maltosa is able to utilize phosphonoalanine as sole nitrogen source. Other phosphono derivatives could not serve as sole source of nitrogen, carbon, or energy.

Herbicide Applications on Wheat and Stubble for No‐Tillage Corn1

AbstractNo‐tillage corn (Zea mays L.) production following winter wheat (Triticum aestivum L.) is increasing in the central Great Plains. Timely weed control is essential to reduce weed seed production and loss of soil water. This research dealt with the effects of applying herbicides to wheat grown on a fine‐silty, mixed, mesic Typic Argiustolls soil, in North Platte, NE, and herbicide applications 5,20, 35, 50, and 260 days after wheat harvest. Applying metribuzin [4‐amino‐6‐(1,1)‐dimethylethyl)‐3‐(methylthio)‐1,2,4‐triazin‐5(4H)‐one] to wheat reduced post‐harvest weed biomass 24 to 81%. When herbicide application was delayed until 50 days after wheat harvest, as compared to 5,20, or 35 days, barnyardgrass [Echinochloa crus‐galli (L.) Beauv.] populations before and after corn planting were the highest. The addition of glyphosate [N‐(phosphonomethyl)glycine], paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion), or terbutryn [N‐(1,ldimethylethyl)‐ N'‐6‐(methylthio)‐1,3,5‐triazine‐2,4‐diamine] + 2,4‐D [(2,4‐dichlorophenoxy)acetic acid] to atrazine [6‐chloro‐N'‐ethyl‐N'‐(l‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] sometimes improved corn yields, when applied after wheat harvest, compared with plots treated with atrazine alone. Optimum corn grain yields were obtained when plots treated with atrazine + paraquat at 5, 20, and 35 days after wheat harvest were sprayed with cyanazine {2‐[[4‐chloro‐6‐ (ethylamino)‐1,3,5‐triazin‐2‐yl]amino]‐2‐methylpropanenitrile} preemergence or handweeded once after the corn was planted. Delaying post‐wheat harvest herbicide application for 260 days reduced corn yields 20%.

Efficacy of selected herbicide mixtures for weed control in sugar cane

SummaryThree trials were conducted over two cropping seasons, on portions of the production fields of the Nigerian Sugar Company sugar-cane estate, Bacita, to evaluate the efficacy of several herbicide mixtures for weed control in sugar cane using the varieties Co. 957 and Co. 1001. With a broad spectrum of weeds, early post-emergence applications of diuron + hexazinone (2·0 + 0·7 kg a.i./ha) followed by hexazinone + paraquat (0·5 + 0·3 kg a.i./ha) about 8 weeks after the first application gave satisfactory weed control that resulted in high cane yields. Addition of glyphosate to the mixture for the first application or its substitution for paraquat in the second application, or both, resulted in increased suppression of nutsedge. This was, however, more phytotoxic to the sugar-cane plants. Addition of pendimethalin to either diuron or hexazinone improved the control of grass weeds. Hexazinone-based mixtures were found to give longer-lasting weed control than the diuron-based mixtures. Both diuron and hexazinone were generally more selective on Co. 957 than on Co. 1001. The degree of weed infestation between 6 and 12 weeks after planting was inversely related to cane yield.

Influence of Glyphosate (N-(Phosphonomethyl)Glycine) on Performance and Selected Parameters in Broilers ,

Glyphosate (N-(phosphonomethyl)glycine), Roundup,3 the herbicide formulation of the isopropylamine salt of glyphosate, was fed to male and female broiler chickens at 0, 60.8, 608, and 6080 ppm from 1 day to 21 days of age. Parameters measured were body weights, bone weights and lengths, bone ash, inorganic phosphorus, calcium, magnesium, and calcium to phosphorus ratios of tibiotarsus bones.There were no consistent significant differences among the control, 60.8, or 608 ppm groups in any of the parameters measured. The addition of glyphosate to feed at the highest dose level (6080 ppm) reduced body weight approximately 50% in both sexes as early as 7 days of age, and this reduction continued for the rest of the experiment. The highest dose level increased the calcium and magnesium content of the tibiotarsus bones.

Effect of Glyphosate on Membrane Permeability in Red Beet (Beta vulgaris) Root Tissue

When discs of red beet (Beta vulgarisL.) root were immersed in various concentrations of glyphosate [N-(phosphonomethyl)glycine] either in phosphate (pH 6.8) or citrate (pH 6.2) buffer, no efflux of betacyanin occurred even after 1 week. This suggests that glyphosate had little or no effect on membrane permeability. When beet discs were immersed in distilled water containing glyphosate, the betacyanin efflux increased with time and concentration. Measurement of pH indicated that the solutions were strongly acidic at first, but tended to approach a pH of 6.0 over 8 h, after which time betacyanin efflux slowed down or stopped. The tissue was able to buffer the solutions sufficiently to prevent further efflux. When tissue discs were immersed in a series of citrate buffer ranging from pH 3 to 6.2, efflux occurred at pH 3 and slightly at pH 6.2. Efflux was not altered significantly with the addition of glyphosate.