Weed Control

Electrochemical oxidation of the GH herbicide

Na2so4 Nacl

We began our investigation by carrying out the electrochemical oxidation of an standard GH sample. Once the most efficienty electrolysis conditions had been established, the electrooxidation of a commercial formulation (Roundup ) was also investigated. Cyclic voltammograms in both the absence and presence of GH were conducted. Electrochemical characterization showed that GH is not electroactive in the potential window 0.2 -1.2 V vs. SCE, so its oxidation hindered by OER. This is a very common...

Conclusion

A number of genes have been employed for the generation of genetically-modified crops possessing tolerance to herbicides in an effort promote crop growth and discourage the growth of competing plants such as weeds. Herbicide-resistant genes are also invaluable for use as selectable markers in the genetic transformation of plants. The majority of herbicide-resistant genes are derived from soil bacteria such as Agrobacterium and Streptomyces, organisms which have never been utilized as...

Molecular dynamics simulations of PSIIatrazine complex Relevance for biosensor applications of PSII

Bond Gromacs

As already detailed above, atrazine is known to bind in the eukaryotic D1 protein region encompassing residues Phe211-Leu275, that partially overlap the QB binding pocket (Giardi et al., 1988 Oettmeier 1999). Analysis of mutations conferring herbicide resistance or sensitivity indicated that Ala 250, Ala251 and Ser264 are located close to the atrazine binding pocket and probably directly interact with it (see above, Oettmeier 1999 Johanningmeier et al., 2000). Using this information, in the...

Imazamox Isomer Normal Phase

OO fluroxypyr butoxypropyl ester fluroxypyr-butoxypropyl 3. Chromatographic methods for chiral herbicides 3.1 Separation of chiral herbicides by HPLC HPLC combined with kinds of CSPs is one of the most common and easily obtained approaches for enantiomer analysis and preparation. Today, CSPs have been developed at least seven classes, including Pirkle-type CSPs, polysaccharides CSPs, cyclodextrins CSPs, macrocyclic glycopeptide antibiotics CSPs, proteins CSPs, crown ethers CSPs and ligand...

Herbicides weed control and sesame tolerance

Several herbicides provide excellent control of weeds with minimal to no damage to sesame. However, in evaluating herbicides, there have been conflicting results, and it is difficult to sort out why some herbicides work in one area and do not work in another. Also, in some cases, at the same location, the herbicides effectively control weeds and little sesame injury is noted in one year however, the opposite may be true the following year. With most herbicides, herbicide dose, formulation, soil...

Online preconcentration

Cad Valve Diagram Hplc

Solid phase extraction could be performed on-line by direct connection to the chromatographic system, therefore fully automated technique could be utilised. Hyphenated on-line SPE-HPLC systems are designed to improve not only sensitivity and selectivity of determination but also reduced sample manipulation and time, better intra-and inter-day reproducibility, higher sample throughputs as well better precision due to lower human participation, but typically requires the use of program controlled...

Introduction

No-tillage (NT) is the extreme form of conservation tillage where the soil is left undisturbed before planting and crops are just planted into residues left on the soil surface (Morse 1999a). The direct seeding of large-seeded vegetables has generally provided successful crop establishment in NT production systems, although many vegetable crops can easily be transplanted in NT production systems including broccoli (Brassica oleraceae var. italica), cabbage (Brassica oleraceae var. capitata),...

INTECH open

Free online editions of InTech Books and Journals can be found at www.intechopen.com Part 1 Weed Control and Crop Management 1 Chapter 1 Weed Control in Conservation Agriculture 3 for No-Tillage Vegetable Production 17 of Herbicides in Sesame Production 41 W. James Grichar, Peter A. Dotray and D. Ray Langham Chapter 4 Defining Interactions of Herbicides with Other Agrochemicals Applied to Peanut 73 David L. Jordan, Gurinderbir S. Chahal, Sarah H. Lancaster, Joshua B. Beam, Alan C. York and...

Pendimethalin Review In Sesame 2008 To 2016

In-season applications of glyphosate for control of redvine (Brunnichia ovata) in glyphosate-resistant soybean. Weed Technol. 18, 325-331. Anil, K. & Thakur, K. S. (2005). Effect of sowing method and weed control practices on production potential of sesamum (Sesamum indicum)-based intercropping system under rainfed condition, Indian Journal of Weed Science 37, 133-134. Anonymous. (1973). Report 1972-3, Institute of Agricultural Research. Ethiopia, p. 168....

References

Q., Jiang, S. R., Zhou, Z. Q., (2006), Enantiomeric separation of chiral pesticides by high-performance liquid chromatography on an amylose tris-(S)-l-phenylethylcarbamate chiral stationary phase, Journal of Separation Science, 29, pp. 265-271. Hamper, B. C., Dukesherer, D. R., Moedritzer, K., (1994), Analytical and preparative separation of the enantiomers of pyrazole phenyl ether herbicides on three chiral stationary phases, Journal of Chromatography A, 666, pp....

Conclusion and future perspectives

The exploitation of herbicides for weed control is vital to increase the yields and productivity in agriculture. Without the use of herbicides, it would have been impossible to fully mechanize the production of cotton, sugar beets, grains, potatoes, and corn. As a consequence, given the harmful economic implications of poor harvesting, herbicide production is the principal driver of the farming industry. However, the continuous and massive application of these compounds can negatively affect...

Herbicide absorption and translocation

Contact Translocated Weed Killers

The biological activity of herbicide within a plant is a function of absorption, translocation, metabolism, and susceptibility of the plant to the herbicide and or to its metabolites. Because of that, the simple act of an herbicide reaching the leaf surface - or roots, in the case of a soil-applied herbicide - does not guarantee its effective action (Silva et al., 2007). The herbicide needs to be absorbed and translocated to reach the organelle where it will express its herbicidal activity. An...

Membrane technology A short review of potable water treatment 21 Membrane processes in water treatment

Since the early 1990's membrane filtration has gained momentum and is now considered mainstream technology for removing a broad spectrum of contaminants from water and effluents. Advances in materials science and membrane manufacturing technology have shaped this trend, together with the increased regulatory pressures as well as an increased demand for drinking water originating from water sources of inferior quality (surface water, other). Moreover, membrane technologies have emerged as a very...

The role of membrane characteristics

The success of pesticides removal from potable water by membrane processes is strongly related to the type of membrane selected. Important aspects to consider when choosing an appropriate membrane are MWCO, porosity, degree of ionic species rejection, surface charge and membrane type (polymer composition). The significance of each parameter on pesticides removal is directly related to the solute properties (molecular weight, molecular size, acid disassociation constant-pKa, and hydrophobicity...

Herbicide translocation through plasmodesmata

Example Apoplastic Symplast Herbicide

All herbicides applied to the leaves of plants with C4 metabolism must penetrate the vascular bundle sheath cells in order to achieve xylem and or phloem (Vidal, 2002). Once these cells are highly lignified (suberin may also occur in some monocots), the movement of the herbicide molecules from cells in the mesophyl to the cells of the vascular bundle sheath occurs exclusively by plasmodesmata present this interface (Osmond & Smith, 1976). This is the only way the herbicide can reach the...

How to assess the impact of herbicide exposure on soil microbial communities

Although the desorption of an herbicide from soil particles into the aqueous phase facilitates its biodegradation, the bioavailable fraction is also a potential risk for non-degrading microbial populations. Microbial-mediated processes in soils are of critical importance to ecosystem functions, including transformation of organic matter, nutrient release and degradation of xenobiotics. Therefore, an active soil microbial population is considered a key component of good soil quality (Parkin et...

PCA and cluster analysis Previous experiments for soil extraction OA

Table 2 shows the previous tests designed to characterize the influence of the variables that would be further optimized with the OA after their analysis by PCA and Cluster techniques. These experiments were designed taking into account the Kovacs series of extraction solvents (Kovacs, 1996), together with the use of water and different modifiers (acetic acid and ammonium hydroxide) in order to increase recoveries of ionic herbicides as already detailed in section 2.3. Acetone was chosen as the...

Phenoxycarboxylic acid herbicides

The herbicidal effect of 2, 4-D was first discovered by Amchem company in 1942 (Kuang et al., 2006b), and more categories were developed by a lot of companies since 1945 based on the structure of 2, 4-D. The general formula of this class herbicides see fig 1 and the chemical structure of some most used phenoxycarboxylic acid herbicides were summarized in table 2. 2, 4-D is the world's largest broad-leaved weed herbicides. Phenoxycarboxylic acid Class of Herbicides EU U. S. A Japan China Table...

Electrochemical oxidation of different formulations

A reduced number of papers deal with the oxidation of herbicides using electrochemical methods indeed, the majority of the works focuses on photochemical processes. However, a literature search reveals that there is increased interest in the former subject. Table 3 lists the latest papers dealing with the electrochemical degradation treatment of herbicides. Studies of Diuron photocatalytic degradation show that the herbicide mineralization rate reaches almost 97 after 8 hours of irradiation...

What is cyanazine

Boom Sprayer Diagram

Cyanazine is a synthetic chemical that is widely used as a pre-emergence herbicide to control broad-leaf weeds and grasses in agricultural crops. This chemical is in the s-triazine family of herbicides. Some common trade names for cyanazine include Bladex and Fortrol. Cyanazine is also available commercially premixed with another s-triazine, atrazine. Cyanazine was first registered for use as an herbicide by Shell Chemical Company in 1971. In the U.S., over 90 of its use in agriculture is to...

Trifluralin and Pendimethalin

The dinitroaniline herbicides, such as trifluralin and pendimethalin, are used to reduce weed populations and aid in the establishment and production of many crops including groundnut, soybean, and grain sorghum (Dotray et al., 2004 Grichar & Colburn, 1993 Grichar et al., 2005a, b Grichar, 2006). The dinitroaniline herbicides provide excellent control of annual grasses (Buchanan et al., 1982 Chamblee et al., 1982 Wilcut et al., 1995) and are the only soil-applied herbicides registered for...

The role and application of bioassay techniques on the impact assessment of herbicides

Bioassays or biological tests applied to the study of herbicides are based on the response of different species, chosen as controls, to the application of the herbicide under study (Horowitz, 1976). They represent a valuable and necessary tool that provides an overview of soil-plant-herbicide relationships (Rahman et al., 1993 Hern ndez-Sevillano et al., 1999). Although there are chemical methods of analysis accurate and simple to use, bioassays have certain advantages in the study of...

Sulcotrione mgL

The correlation between serum sulcotrione and tyrosine in male rats from the medium- and high-dose groups. 3.4. Effects of sulcotrione on hepatic enzymes involved in tyrosine catabolism, tyrosinemia, and blood glucose in rat. 3.4.1 Physical observation and mass gain No sign of toxicity was observed in sulcotrione-treated animals until end of experiment and there were no changes in mass gain between controls and sulcotrione-treated animals (date not shown). 3.4.2 Effects of sulcotrione...

Peanut production systems

Mechanized production systems utilize a wide range of agrochemicals to manage peanut growth and development and minimize the impact of pests on peanut yield and quality (Lynch and Mack, 1995 Sherwood et al., 1995 Wilcut et al., 1995). Pests that can potentially impact peanut are diverse (Table 1). Yield loss from weed interference or from damage caused by insects, diseases, and nematodes can be substantial in peanut if pest control strategies are not implemented in a timely manner....

Speciesspecific properties of ALS mutations

As mentioned above, the degrees of resistance of Arabidopsis and rice recombinant ALS proteins with identical mutations to PCs are very similar. However, the sensitivity of transgenic Arabidopsis to PCs indicated that the degree of resistance to PCs of transformants expressing Arabidopsis mALSs was greater than those of transformants expressing rice mALSs (Figure 4). It is known that plant ALSs have a signal peptide that is required for translocation of the protein into the chloroplast...

Mutated ALS genes as plastid sustainable markers

Tobacco Metabolism

The employment of some plant-origin genes for herbicide tolerance has solved the problem and allayed the public's anxiety. We have focused on the use of mALS genes as sustainable markers. It is well known that ALS imparts herbicide tolerance by mutation at several amino acid residues (Figure 2). Herbicide-tolerant plants have been reported for rice, tobacco and Arabidopsis (Chang et al., 1998 Tan et al., 2005 Shimizu et al., 2002 Kawai et al., 2007b Okuzaki et al., 2007). Several mutated...

Pyrazine herbicides

Outlawed Herbicides

The most successful pyrazine derivative was diquat-dibromide (see Fig. 1, the structure I). This non-selective, contact herbicide has been used to control many submerged and floating aquatic macrophytes which interferes with the photosynthetic process, releasing strong oxidizers that rapidly disrupt and inactivate cells and cellular functions (at present banned in many EU countries). Severe oral diquat intoxication has been associated with cerebral haemorrhages and severe acute renal failure...

Patented pyrazine herbicides

The control of unwanted vegetation by means of chemical agents, i.e. herbicides, is an important aspect of modern agriculture and land management's. While many chemicals that are useful for the control of unwanted vegetation are known, new compounds that are more effective generally, are more effective for specific plant species, are less damaging to desirable vegetation, are safer to man or the environment, are less expensive to use or have other advantageous attributes, are desirable (Benko,...

Photosynthesisinhibiting pyrazine analogues of chalcones

Chalcones and related compounds chalconoids are aromatic ketones containing two aromatic rings linked with three carbon chain. The presence of an unsaturated double bound is typical for chalcones. Hence, chalcones are 1,3-diarylprop-2-ones. They show antibacterial, antifungal, antitumor and anti-inflammatory properties (Dimmock et al., 1999). The aim of our project was the isosteric replacement of a phenyl moiety in chalcones with the pyrazine ring to form some pyrazine analogues of chalcones...

Molecularly imprinted polymers

Guidewire Shapes

Molecularly imprinted polymers (MlPs) are highly crosslinked polymers with specific binding sites for a particular analyte. The print molecule - called the template - is chemically coupled with one or several functional monomers and then spatially fixed in a solid polymer by the polymerisation reaction. After template removal by extraction, polymers with imprints, which are complementary to the template in terms of size, shape and functionality are obtained. These polymers are able to rebind...

Effect of pesticides properties on retention

According to the preceding discussion, the selection of an appropriate membrane is primarily made on the basis of key pesticide parameters, like the molecular weight, the molecular dimensions (length and width), the polarity (dipole moment), the hydrophobicity hydrophilicity (logKow), and the acid dissociation constant (pKa). Several research groups have systematically studied the role of one or more of the aforementioned pesticide parameters on membrane rejection, and their results are...

Production systems for NoTillage vegetables

Several different production systems have been evaluated for NT vegetables. Although the vegetable crop planting method plays a major role in the successful production of NT vegetables (Table 1), the production system utilized for NT vegetables has shown to have a definite influence on the resulting productivity of the crop. A bare soil NT system will improve weed control compared to CT (Moore et al. 1994, Walters et al. 2008), since the use of NT avoids bringing new weed seeds closer to the...

Optimization experimental designs Orthogonal Arrays

The optimization of any process can be tried either by the trial and error method, the one-at-a-time design or achieved by experimental design methods. The one-at-a-time design is a classical Univariate method which consists of investigating the response for each factor while all other factors are held at a constant level. Therefore, the variation of response can be attributed to the variation of the factor. They are time-consuming methods which do not take interactive effects between factors...

Description of analytical methods and biosensors for herbicide detection

This unhealthy scenario requires the challenging development of sensitive analytical control systems to reveal the presence of herbicides and protect humans and ecosystems. Properly assembled biosensors can satisfy these requirements, also providing reliability and flexibility of the assays (Giardi & Pace, 2005). A major difficulty in estimating environmental quality related to herbicides contamination is due to seasonal change of field application and the extremely low levels of the maximum...

Relevance of bioinformatic tools Molecular docking binding energy calculation and molecular dynamics

In silico studies of macromolecular systems are becoming increasingly useful and reliable with the improvement of our knowledge of their physico-chemical properties and with the availability of more powerful hardware resources. Nowadays, structural bioinformatics tools coupled to modern molecular biological techniques allow the tailoring of macromolecules as high affinity receptors for organic compounds of biomedical environmental industrial relevance to be used as biosensing devices for these...

How can we select bona fide target

Most of the herbicides attack to the unique biochemistry of plants causing severe disruption of the plant metabolism. These are usually inhibitors of specific enzymes binding either at the active site of the enzyme or at some domain apart from the active site (Berg et al., 1999 Dayan et al. 2009). Among the strategies to identify suitable targets, one strategy was to assume that if an enzyme in a pathway or process is a target, then others in the same pathway or process might be too. The...

Discovery of 7keto8aminopelargonic acid synthase

In a pioneering pilot study (Jun et al., 2002), Arabidopsis antisense lines were created using randomly selected cDNAs. These lines were then scored for mutant phenotypes and analyzed genetically to exclude mutants that were clearly not caused by antisense inhibition of gene expression. At present, about 10,000 genes have been put through the entire process, including confirmation by independent retransformation, and 46 potential herbicide targets have been identified. These are genes whose...

Photosynthetic electron transport in photosystem II

Photosystem II uses light energy to drive two chemical reactions the oxidation of water and the reduction of plastoquinone. Five of redox components of PS II are known to be involved in transferring electrons from H2O to the plastoquinone pool the water oxidizing manganese cluster (Mn)4, the amino acid tyrosine (Yz), the reaction center chlorophyll (P680), pheophytin, and two plastoquinone molecules, QA and Qb (Fig. 5). Tyrosine, P680, pheophytin (Pheo), QA, and QB are bound to two key...

Biosensors already developed

Although a variety of whole-cell-based bacterial sensors have been applied in environmental assays for pollutant monitoring, generally they display a poor response to herbicides Table 3 . If the electron transfer from the reaction centre to the quinone pool is blocked, such as during the binding of the photosynthetically active pesticides, these parameters change dramatically and can be monitored by electro-optical analysis in a pesticide concentration dependent manner Figure 6 . In this...

Plasmodesmata

Plasmodesmata

In a simple way, plasmodesmata are plasma membrane channels that pass through the cell wall, which not only allow for communication between plant cells, but also facilitate direct intercellular translocation of ions, photosynthates, growth regulators, and macromolecules of xenobiotics with similar characteristics (Robards, 1976). They provide a direct cytoplasmic connection between neighboring cells through cell walls. The properties of these communication channels are a factor in the...

Examples of water treatment plants using Nfulpro membranes

A list of significant water treatment plants using nanofiltration or ultra-low pressure RO membranes is shown in Table 2. An outstanding example of nanofiltration for the removal of pesticides and other organic residues, for the production of drinking water, is the Mery-sur-Oise plant in the northern part of Paris, in France. The Mery-sur-Oise plant has been successfully producing water from the river Oise, using NF technology, since 1999. Its performance indicators are very satisfactory,...

Reversal study

Reversal effect was estimated via chlorophyll contents to foliar application and via germination. Germination test Seeds of A. thaliana were germinated in 55 mm plastic Petri-dish lined with one-layer filter paper (Advantec No. 2). About 1 mL of each TPTA solution dissolved in absolute acetone with various concentrations of 0, 0.063, 0.0125, and 0.025 mM was spread evenly onto the filter paper (0 5 cm), respectively and allowed to dry in a laboratory fume hood. After that, 1 mL of distilled...

Metolachlor and Smetolachlor

Metolachlor or S-metolachlor are commonly used in various crops for control of small-seeded broadleaf weeds, some annual grasses, and yellow nutsedge (Grichar et al., 1996). S-metolachlor will control small-seeded annual grasses, but does provide inconsistent control of large-seeded annual grasses (Grichar et al., 2004a 2004b). Many growers have reported peanut stunting when soil applications of metolachlor have been followed by rain (Grichar et al., 1996). Grichar et al., (1996) reported that...

Outcrossing in wheat The problem of coexistence

The Exponential Wheat Problem

Wheat is a self-pollinating crop but outcrossing is possible between cultivars at variable rates that are related with populations, genotypes and environmental conditions (Jain, 1975). The main studies on pollen dispersal in wheat appear in two stages. In the 1960s and beginning of the 1970s managing pollen drift was a major concern within the context of commercial production of hybrid wheat, where achieving high levels of genetic purity and satisfactory seed set on male sterile plants were...

ALS and ALSinhibiting herbicides

Als Herbicide

ALS is a common enzyme that catalyzes the first step of the biosynthetic pathway of the branched-chain amino acids valine, leucine and isoleucine. ALS is the primary target site for at least five structurally distinct classes of herbicides including sulfonylureas (SUs), imidazolinones (IMs), triazolopyrimidine sulfonamides (TPs), pyrimidinylsalicylates (pyrimidinylcarboxylates, PCs), and sulfonylaminocarbonyl-triazolinones (Figure 1, see the chapter written by Sato et al.) (Shimizu et al.,...

Soil dissipation research

Dt50 Dissipation

The exponential decay equation 1 effectively describes halosulfuron dissipation (Figure 3). First-order dissipation rate constants (k) for halosulfuron were less (i.e. slower dissipation) for soil under low density polyethylene mulch (0.07) than for bare soil (0.10). Halosulfuron dissipation for bare soil dropped to undetectable levels by 27 and 28 days after treatment in two studies, respectively. This trend was similar for soil under low density polyethylene mulch. From equation 2 , the DT50...

Effect of the feed water composition

Membrane filtration experiments with real or simulated raw waters (i.e. solutions containing salts, organic matter and pesticides) have shown that pesticide rejection can vary greatly, depending on the feed water composition. Specifically, pH, ionic strength, and the presence of organic matter are identified as having an influence on pesticide rejection. The respective literature results are discussed next. The role of pH on pesticide rejection is related mainly to the changes taking place in...

Fluometuron

Fluometuron controls many annual dicotyledon weeds, however, it does not completely control some of the more troublesome weeds found in crops such as cotton (Burke & Wilcut, 2004). These troublesome weeds that fluometuron does not completely control include Amaranthus spp., Ipomoea spp., prickly sida (Sida spinosa L.), and sicklepod (Senna obtusifolia L.) (Buchanan, 1992 Crowley et al., 1979 Culpepper & York, 1997). Fluometuron applied postemergence may injure cotton and delay maturity...

Clethodim Fluazifop Pbutyl Sethoxydim and Haloxyfop

Large seed grasses such as Texas millet Urochloa texana (Buckl.) R. Webster and rhizome johnsongrass can be a serious problem in sesame fields and are not controlled with current preemergence herbicides therefore, postemergence grass herbicides are an absolute necessity. Postemergence control of annual grasses can be obtained with several herbicides (Grichar, 1991 a,b Prostko et al., 2001). Grichar (1991a) found that sethoxydim applied early postemergence provided more effective annual grass...

Herbicide Herbicide interactions

A considerable amount of research has been conducted to define interactions among herbicides used in peanut. Herbicides applied in combination either preplant incorporated or preemergence generally increase the spectrum of weed control or the length of residual weed control (Wilcut et al., 1987b 1995). For example, pendimethalin is often applied in combination with alachlor, dimethenamid-P, metolachlor, or S-metolachlor to improve early season weed control (Bridges et al., 1984 Wehtje et al.,...

Reference Of Weed Control

Interactions of foliar insecticides applied with pyrithiobac. Weed Technol. 9 512-517. Askew, S. D., J. W. Wilcut, and J. R. Cranmer. 1999. Weed management in peanut (Arachis hypogaea) with flumioxazin preemergence. Weed Technol. 13 594-598. Bailey, J. A. and G. Kapusta. 1994. Soil insecticide and placement influence corn (Zea mays) tolerance to nicosulfuron. Weed Technol. 8 598-606. Bailey, W. A., J. W. Wilcut, D. L. Jordan, C. W. Swann, and V. B. Langston....

Optimization of operational variables Herbicide soil extraction OA

The average recoveries were used as the output variable to optimize. Different OA were developed for acidic analytes and for basic and neutral herbicides due to dual methyl ester formation from the TMSH derivatization of acids and their ester forms prior to their GC analysis, in order to know which form the methyl ester came from. After carefully studying the results obtained from the previous experiments analyzed by PCA, the following variable values were selected for the multiresidue...

Herbicide soil extraction OA results

Table 6 shows the average recovery data obtained by duplicate for each of the 9 experiments. For the regular analysis, an ANOVA table with pooled errors was calculated from these experimental data in order to identify individual sources of variation and to calculate the contribution of each factor to the response variation (Table 7). ANOVAs of the recovery data obtained for both matrices revealed that factor S, the type of solvent, contributed by the highest percentage to the variability of the...

Glyphosate contamination

In recent years, the intensive use of herbicides has increased environmental concern, partly because of the adverse effects of these chemicals on soil and aquatic microorganisms (Farah et al., 2004). One of the most commonly employed agrochemicals is glyphosate (Fig. 1). N-(phosphonomethyl) glycine is a highly effective broad-spectrum, post-emergence, non- ClO-(sol) + R CO2 + inorganic ions + H+ + e-ClO-(sol) + RCl R selective herbicide widely used in agriculture worldwide (De Amarante et al.,...

Bioassays in selectivity and resistance to herbicides

The basis for much of the work done in crop-weed management is weed control. In areas of well-developed agriculture weed control is mainly based on chemical control by herbicides. The extensive and redundant use of herbicides could present problems both in agricultural systems and in the surrounding environment. To detect any possible effect of herbicides in the plant and to test herbicides efficacy, response assays and tests must be carried out at various levels in the laboratory, greenhouse...

Isoprenoid biosynthesis pathway

Isopentenyl diphosphate (IPP) is the central intermediate in the biosynthesis of isoprenoids, the most ancient and diverse class of natural products. Two distinct routes of IPP biosynthesis occur in nature, the mevalonate pathway and the recently discovered deoxyxylulose 5-phosphate (DOXP) pathway. The evolutionary history of the enzymes involved in both routes and the phylogenetic distribution of their genes across genomes suggests that the mevalonate pathway is unique to archaebacteria, as...

Perkinsus proliferation can also be affected by herbicides derivatives

To demonstrate the advantages of the usage of Perkinsus as an alternative for the screening for new drug targets affecting viability proliferation of the parasite and thus identification of possible drug precursors among known herbicides, a test using the most common herbicides was developed. Ten herbicides were chosen between the most frequently used worldwide (see Table 3). Other aspect taken into consideration was the choice of a non dinitroaniline, phosphorothioamidate or...

Hydrophilic polymeric sorbents

The hydrophilic polymeric sorbents are obtained by chemical modification of the existing hydrophobic materials or by copolymerisation of monomers that contain suitable functional groups. The polar substituents reduce the interfacial tension between the polymer surface and aqueous sample improving the wetting characteristics and increase contact between the analyte and polymeric sorbent. Strata-X (styrene skeleton modified with a pyrrolidone group) and Oasis HLB (macroporous...

Quantification of glyphosate

Ruhemann Purple

The chemical structure of GH does not display a chromophore group, so spectroscopic determinations have to be performed only after its derivatization reaction. Hereafter, two different derivatization reactions for GH determination were used. The first derivatization consisted of the reaction of ninhydrin in the presence of the Na2MoO4 catalyst at 100 C (Bhaskara & Nagaraja, 2006), which produces the Ruhemanns purple product with a maximum absorption at 570 nm (Fig. 2A). GH degradation was...

Infusion of POEA

In our study, although POEA did not significantly affect MABP during the infusion period, it progressively depressed left-side ventricular function (decreased the CI and LVSWI and increased the PCWP and CVP), and increased pulmonary vasoconstriction effects (increased the MPAP and PVRI) during and after its infusion, leading to metabolic acidosis with the accumulation of lactate noted at 60 min and at the end of the experiment. In the POEA group, 66.7 (4 6) of the piglets died between 1 and 3 h...

Herbicide resistance as a marker for gene flow

In spite of the knowledge of GM herbicide tolerant wheat cultivars, whose use is limited by availability and regulatory constraints, in the experiments presented in this book chapter we have used non GM wheat cultivars possessing homozygous dominant genes for herbicide response. Chlorotoluron and difenzoquat tolerant wheat cultivars were used to obtain hybrid-resistant progenies detectable by herbicide selection. The herbicide chlorotoluron is a commercially available selective phenylurea that...

The genus Perkinsus

The microorganisms of the genus Perkinsus are protist parasites responsible for important mortalities in different mollusc species. It was first described in 1946 as a spherical unknown organism found in moribund Crassostrea virginica oysters but not in healthy ones in Louisiana (USA) (Mackin et al. 1950). For the past two decades a severe mortality is affecting bivalve molluscs particularly in Portugal and Spain (Leite et al. 2004). This mortality was first associated with the parasite...

Infusion of IPAG

In contrast to G and IPA, POEA and IPAG infusions introduced high death rates. IPAG infusion lowered cardiac contractility and the MABP, accompanied by increases in the MPAP and vascular resistance, which caused heart failure. A 66.7 fatality rate and blood lactate formation with lowered BE values were noted following its infusion with 50 of the dose in the concentration similar to other chemicals. No pulmonary rales were detected by auscultation during the experiments, and no hypoxemia, severe...

Animal model

We used male Landrace piglets (aged 6-8 weeks, body weight 8-15 kg) as the model for the study. The piglets were fasted for one day before surgery. Each piglet was initially sedated with an intramuscular injection of ketamine (20-30 mg kg Ketalar 50 mg mL, UBI Asia, Hsinchu, Taiwan) and atropine (0.05 mg kg) and then placed in a supine position on a thermally controlled blanket on an operating table. A percutaneous venous cannula (24G) was placed into the piglet's marginal vein of the pinna,...

Electrolytic system and electrodes

The results from GH degradation presented in this chapter were obtained using the experimental conditions described below. The electrochemical measurements were conducted in an open system, using a three-compartment electrolytic cell consisting of a main body (50 mL solution) and two smaller compartments containing the counterelectrodes, which were isolated from the main body by coarse glass frits. The electrolyses experiments were accomplished in the galvanostatic mode, under magnetic...

Electrolysis in chloride media and formation of organochlorinated compounds

Knowing that electrochemical remediation seeks more powerful oxidizing conditions, the electrolysis in chloride medium is a good alternative when more efficienty organic compound oxidation is desirable. NaCl is one of the most attractive media in the field of indirect oxidation owing to its straightforward impact on electrochemical technology. Oxide electrodes such as DSA anodes are very active for Cl2 evolution, so many studies have reported on quite advantageous features concerning the use of...

DSA electrodes

The metallic oxide electrodes introduced by Beer in 1966 consist of an inert metal support coated with noble metal oxides such as RuO2 and IrO2. In addition to the noble metal oxides, oxide electrodes also contain the so-called modulators, which are oxides such as SnO2, TiO2, Ta2O5, and PbO2, whose function is to enhance the electrochemical characteristics related to electrode lifetime, mechanical stability, and catalytic activity, not to mention cost reduction. Electrode preparation is usually...

Retention mechanisms in NFRO processes

There is a great deal of published work on the basic retention mechanisms and the various applications of NF RO processes (Mulder, 1996 Scott, 1998 Nghiem & Sch fer, 2005). In general, the separation process involves several mechanisms such as size exclusion or charge repulsion. Moreover, a sorption-diffusion mechanism can also contribute to the separation process, attributed to hydrophobic interactions or hydrogen bonding between the contaminants and the membrane surfaces (solute-membrane...

Membrane fouling

Membrane performance can be negatively affected by a number of species whose concentration and or presence in the feed water must be controlled. As indicated in Fig. 5, these species are divided in two categories substances capable of damaging the membranes and species with potential for membrane fouling or scaling. The discussion is concentrated on fouling, which is the major problem faced in any membrane separation. Membrane fouling, if not controlled, is detrimental to the overall process...

Optimization of operational variables Acidic herbicide analysis OA

Acidic herbicides were divided in two groups, those only present in their acidic form and those also esterified. These esters were called original to differentiate them from the methyl esters produced after derivatization. Due to dual methyl ester formation, different OA were developed for the acidic herbicides (named Acid matrix) and for the original esters (named Ester matrix) in order to know which form the methyl ester came from and the way factors affected both esterification and...

Carbon nanotubes

Carbon nanotubes (CNTs) represent the novel carbon-based nanomaterials with unique properties such as high surface areas, large aspect ratios, remarkably high mechanical strength as well as electrical and thermal conductivities. They can be described as a graphite sheet rolled up into a nanoscale-tube. Two structural forms of CNTs exist single-walled (SWCNTs) and multi-walled (MWCNTs) nanotubes. CNT lengths can be as short as a few hundred nanometers or as long as several microns. SWCNT have...

Low density polyethylene dissipation research

The exponential decay equation 1 effectively described dry and irrigated glyphosate dissipation (Figure 4). First-order dissipation rate constants (k) for glyphosate were (i.e. slower dissipation) less for the dry study at 0.008 than for the irrigated study at 0.933. For glyphosate, DT50 for the dry study was 84 hours, while it was 1 hour in the irrigated experiment. Glyphosate concentration dropped to less than 5 mg m2 levels by the 2nd irrigation event at 24 hours after treatment. Glyphosate...

Analytical herbicide quantification

Herbicide analytical methods differ by chemical due to variation in solubility, structure, volatility, etc. Therefore, various methods are used to quantify. One common method is the use of high pressure liquid chromatography in tandem with mass spectrometry (HPLC-MS). This procedure allows for accurate measures for many different compounds at extremely sensitive levels of detection. Proper sample handling includes solvent identification, solvent ratios, extraction methods, injection volumes,...

Pollen dispersal in wheat

Wheat pollen dispersal is not a new issue in agriculture. The varietal purity of the seed has always played a fundamental role in the development, yield and final quality of crops. It has long been known that pollen contamination not only takes place in cross-pollinated crops, it is also possible in self-pollinating crops when different varieties of the same crop are cultivated and sufficient separation distance is not maintained (Sanchez-Monge, 1955). One of the most effective methods for...

Production of transgenic maize using a mutated ALS gene derived from host maize DNA

Four commercial hybrid maize varieties resistant to ALS-inhibiting herbicides (IM and SU) were developed by a somatic cell selection method with a B73 x A188 callus tissue culture (Tan et al., 2005) with a single mutation (W574L, S653N and T155A). A double mutation (P197A and W574L) that showed enhanced resistance to ALS-inhibiting herbicides was later discovered and called a highly herbicide-resistant ALS (HRA). The first transgenic maize resistant to ALS-inhibiting herbicides was produced by...

Weed control

Weed control is a critical farm operation and can significantly affect crop yield. Herbicides have vital importance in weed control and high crop yield however these have potential to produce harmful effects 1 . Herbicides are applied to whole field uniformly without considering the weed density. Weeds are often patchy rather than even or randomly distributed in the crop fields 2 . Total variable costs in 2002 for U.K were within a range of 1,720 ha and 1,870 ha for main crop potatoes, of which...

Herbicide Fungicide interactions

Similar to herbicides and insecticides, timing of application of postemergence herbicides and fungicides to control foliar and soil-borne diseases overlap considerably during the peanut growing season (Table 3). Fungicides are applied beginning approximately 45 days after peanut emergence and can be applied until a few weeks prior to digging and vine inversion. Efficacy of clethodim and sethoxydim can be reduced by co-application with copper-containing fungicides or azoxystrobin,...

Summary and conclusions

The effectiveness of NT production systems depends on the vegetable crop grown, the crop establishment method, establishment of high residue mulch from a cover crop on the soil surface, and available PRE and POST herbicides for the vegetable crop. NT systems seem to work better in those vegetables that 1) have vines that rapidly spread across the soil surface (e.g., cucumber and pumpkin) which suppress weed growth 2) provide rapid canopy closure (e.g., broccoli planted on narrow rows) to...

NoTillage vegetable cropping systems

Several researchers found that cabbage yields in NT were similar to that of CT (Hoyt et al. 1996, Morse 1995, Morse & Seward 1986), although Knavel and Herron (1981) indicated that spring cabbage yields were reduced in NT when compared to CT. Wilhot et al. (1990) related cabbage yield reductions in NT to poor plant establishment impeded crop growth more than to the effects of a NT production system. Furthermore, similar to what has been observed for other vegetable crops, when weed control...

Importance of herbicides for NoTillage vegetables

Some type of herbicide application is generally required to optimize weed control and maximize vegetable productivity in NT systems, since cover crop residues can generally be expected to provide early-season weed suppression (for about the first 4 to 6 weeks) but not full-season weed control. In NT squash (Walters et al. 2004, 2005) and cucumber (Walters et al. 2007) production systems, the use of winter rye enhanced weed control even when a standard herbicide program was used. In NT pumpkin...

Herbicides Theory And Applications

Edited by Sonia Soloneski and Marcelo L. Larramendy Edited by Sonia Soloneski and Marcelo L. Larramendy Janeza Trdine 9, 51000 Rijeka, Croatia All chapters are Open Access articles distributed under the Creative Commons Non Commercial Share Alike Attribution 3.0 license, which permits to copy, distribute, transmit, and adapt the work in any medium, so long as the original work is properly cited. After this work has been published by InTech, authors have the right to republish it, in whole or...