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AbstractSaraca asoca is mythologically important, highly-revered, ancient tree species which is facing vulnerability. Like other members of Fabaceae, ashoka is considered as a highly-recalcitrant species restricting its micropropagation and plant transformation prospects. This study aimed to develop callus and shoot regeneration protocols for ashoka and report its High-resolution mass spectrometry (HRMS)-based metabolomic profile of leaf and callus samples. Different concentrations of 2,4-dichlorophenoxyacetic acid and picloram were observed to successfully induce efficient callus induction from leaf samples while direct shoot induction from leaf explants was not successful irrespective of different concentrations of 6-benzylaminopurine and zeatin tested alone. The HRMS profile of methanolic extract of the leaf and callus samples showed a predominance of flavonoids, phenols, saponins, and alkaloids. We report low concentration of picloram (2 mg/L) as most suitable for the development of loose and friable callus from leaf samples; and detection of 631 and 791 metabolites in the callus and leaf samples, respectively. A total of 474 metabolites were common in both the samples and 1,825 novel uncharacterized metabolites are being reported for the first time. There is a need to establish shoot regeneration protocols for ashoka and detect key metabolites with commercial importance through extractions with multiple solvents. [ABSTRACT FROM AUTHOR]

This study portrays the dissipation behaviour of the herbicide mixture of clomazone and 2,4-D (clomazone 20% + 2,4-D ethyl ester 30% EC) in a rice field system. The combined formulation is widely used in India as it controls a broad spectrum of weeds, but its fate in tropical environment and the risks involved to the consumer as well as to the environment are still unexplored. Therefore, a supervised field trial was conducted following the post-emergence application of clomazone 20% + 2,4-D ethyl ester 30% EC at recommended (625 g a.i./ha) and double the recommended dose (1250 g a.i./ha) in rice in two consecutive seasons (Kharif and Rabi). The analytical methods for both clomazone and 2,4-D validated as per the SANTE guideline. The residues of clomazone were extracted by the modified QuEChERS method and analysed by GC-MS/MS, whereas the residues 2,4-D were extracted by classical partitioning method and analysed by LC-MS/MS. The recovery percentage of both the compounds ranged between 86–95% with LOQ 0.01 mg/kg for all matrices (rice grain, straw, husk, and field soil). The dissipation of both the compounds followed first-order kinetics. The half-life of clomazone and 2,4-D in soil ranged between 1.06–1.27 days and 4.74–6.24 days, respectively. The residues of clomazone and 2,4-D were below quantification level (BLOQ) in the harvested rice co-products (rice grain, husk and straw) and soil samples. Therefore, it can be summarised that the application of this herbicide mixture in rice cultivation will not pose any residual toxicity and the rice grains are safe for human consumption. Besides, the soil ecological risk assessment indicated that both the compounds possess low risk towards earthworm and soil arthropods. However, there was a concern about soil algal toxicity, which needs to be reconfirmed by further studies to establish a conclusive inference. [ABSTRACT FROM AUTHOR]

In recent times, carbon nanofibers (CNF) have been used extensively for the remediation of environment owing to their hollow layered organization, high specific surface area, and strong electrostatic interactions which formulate it as an appropriate adsorbent material. Metallic nanoparticles were blended onto its surface in order to engineer a novel metal-CNF nanocomposite. The study aimed the ultrasonic assisted adsorption of rhodamine B dye (RhB) and pesticide dichlorophenoxyacetic acid (2,4-D) out of aqueous matrix by using silver (Ag) and copper (Cu) based bimetallic composite (Ag-Cu/CNF) material. The synthesized nanocomposites were characterized for its crystalline analysis, textural characteristics, surface chemical bonding, and specific surface area. Ag-Cu/CNF illustrated superior adsorptive efficiency when compared with Ag/CNF and Cu/CNF. Adsorption equilibrium was studied by Freundlich and Langmuir isotherms. Evaluation of the data predicted that Langmuir model described the maximum fit toward equilibrium data with utmost adsorption efficiency of 201 mg/g and 112 mg/g for RhB and 2,4-D, respectively. Also, the comparison between adsorption aided by ultrasound, magnetic stirrer, and vortex shaker assisted methods revealed that sono-sorption is a proficient option for commencement of adsorption phenomenon due to convenient and facile diffusion. [ABSTRACT FROM AUTHOR]

Herbicides are widely used in farmlands worldwide. However, after their application on farmlands, they accumulate in high amounts in continental and marine waters. Herbicides are endocrine disruptors, and are known to cause toxicity, carcinogenicity and mutagenicity. Besides, they also spoil the taste and odor of water bodies. To prevent these effects, it is necessary to perform an in-depth study on various herbicide removal methods. This review discusses the various methods of herbicide removal from aqueous body, using a commonly used herbicide (2,4-dichlorophenoxyacetic acid) as a representative chemical. This paper includes a systematic tabulated review of all reported removal methods with important parameters and their mechanism. Adsorption, biological degradation, electrochemical treatment, Fenton degradation, oxidation, ozonation and photocatalytic degradation are investigated and compared for removal of 2,4-D. The advantages and disadvantages and the factors influencing selection of the aforementioned processes are discussed. [ABSTRACT FROM AUTHOR]

Adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-metylphenoxyacetic acid (MCPA) from aqueous solution onto activated carbons derived from various lignocellulosic materials including willow, miscanthus, flax, and hemp shives was investigated. The adsorption kinetic data were analyzed using two kinetic models: the pseudo-first order and pseudo-second order equations. The adsorption kinetics of both herbicides was better represented by the pseudo-second order model. The adsorption isotherms of 2,4-D and MCPA on the activated carbons were analyzed using the Freundlich and Langmuir isotherm models. The equilibrium data followed the Langmuir isotherm. The effect of pH on the adsorption was also studied. The results showed that the activated carbons prepared from the lignocellulosic materials are efficient adsorbents for the removal of 2,4-D and MCPA from aqueous solutions. [ABSTRACT FROM AUTHOR]

Fruit drop is a major problem resulting in low production and reduction in the income of mango growers in tropical and subtropical regions. Growth regulators, naphthalene acetic acid, gibberellic acid, and 2, 4-dichloro phenoxy acetic acid at the rates of (15, 25, and 35 ppm) were sprayed at full bloom stage on a popular mango cultivar ‘Dusehri’ growing in the subtropical region of Faisalabad in Pakistan. All of the treatments significantly influenced the number of fruits retained at pea, marble, and at harvest stages of fruit growth as compared to the control. Among the treatments, gibberellic acid sprayed at 35 ppm proved to be very effective with 31% more fruit retention than the control. In regard to fruit quality, gibberellic acid (35 ppm) and 2, 4-dichloro phenoxy acetic acid (15 ppm) resulted in a significant enhancement of fruit size in terms of fruit weight (140.8 and 130.1 g), which was 17.6 and 8.7% that of the control (119.8 g), respectively. The treatment 2, 4-D (35 ppm) recorded significantly higher TSS (19.5 °Brix) and TSS to titratable acid ratio over the control. Ascorbic acid content was significantly higher with 35 ppm NAA (61.9 mg/100 ml), while total sugars (20.4%) were significantly higher in 2, 4-D (35 ppm) than the control (11.4%). In general, application of growth regulators resulted in improved fruit retention and fruit quality. [ABSTRACT FROM AUTHOR]

Using a laboratory-scale mixed reactor, the performance of alumina in degrading 2,4-Dichlorophenoxyacetic acid with ozone in the presence of tert-butyl alcohol radical scavenger was studied. The operating variables investigated were the dose of alumina catalyst and solution pH. Results showed that using ozone and alumina leads to a significant increase in 2,4-D removal in comparison to non-catalytic ozonation and adsorption processes. The observed reaction rate constants (kobs ) for 2,4-D during ozonation were found to increase linearly with increasing catalyst dose. At pH 5, the kobs value increased from 19.3 to 26 M−1 s−1 and 67 M−1 s−1 when varying the alumina dose from 1 to 2 and 4 g L−1, respectively. As pH was increased, higher reaction rates were observed for both non-catalytic ozonation and catalytic ozonation processes. Thus, at pH 3 and using a catalyst dose of 8 g L−1, the kobs values for non-catalytic ozonation and catalytic ozonation processes were 3.4 and 58.9 M−1 s−1, respectively, whereas at pH 5 reaction rate constants of 6.5 and 128.5 M−1 s−1 were observed, respectively. Analysis of total organic carbon suggested that catalytic ozonation with alumina achieved a considerable level of mineralization of 2,4-D. Adsorption of 2,4-D on alumina was found to play an important role in the catalytic ozonation process. [ABSTRACT FROM AUTHOR]

Heavy weed infestation poses a major challenge to maize production in Ethiopia. Weed control is practised through hand-weeding or hoeing, both of which are neither adequate nor timely. This study attempts to develop an efficient and economical way of controlling weeds through the use of herbicides, and to evaluate the herbicides for toxicity to microorganisms, particularly plant-parasitic nematodes. Twelve treatments, in a randomised block design with three replications, were used. Sequential applications of atrazine (i.e. atrazine 2.0 kg/ha at pre-emergence followed by 0.25 kg/ha at post-emergence; atrazine 1.0 kg/ha at pre-emergence followed by 0.25 kg/ha at post-emergence) were found to significantly reduce the dry weights of monocots, dicots and total weeds. Pre-emergence applications of atrazine at 2.0 and 1.0 kg/ha, and of pendimethalin at 2.0 kg/ha, reduced dry weight only in dicot weeds. Sequential applications did not inhibit bacterial population growth, but were toxic to plant-parasitic nematodes and fungi, causing a reduction in their abundance. Sequential applications, and single application of atrazine 2.0 kg/ha at pre-emergence, resulted in maize yields, net benefits and benefit-cost ratios higher than other treatments. [ABSTRACT FROM AUTHOR]

Amperometric biosensors using laccase from Trametes versicolor as a bioelement were developed for 2,4-dichloro phenoxy acetic acid (2,4-D). Laccase enzyme was immobilized by gelatin and glutaraldehyde onto a Clark oxygen probe and screen printed electrodes (SPEs). Amperometric and chronoamperometric measurements were carried out with the biosensors. First, the effect of laccase activity on the biosensor performances was investigated for both biosensors, and then optimum pH and temperature and also thermal stability of the biosensors were tested. In addition, the detection ranges of some phenolic compounds were obtained by the help of calibration graphs of them. In repeatability studies, variation coefficients and standard deviations for both biosensors were also calculated by the studies done for this purposes. Finally, the biosensors were applied to the determination of 2,4-D in a real herbicide sample. [ABSTRACT FROM AUTHOR]

Reductive transformation of 2,4-dichlorophenoxyacetic acid (2,4-D) by nanoscale and microscale Fe3O4 was investigated and compared. Disappearance of the parent species and formation of reaction intermediates and products were kinetically analyzed. Results suggest that the transformation of 2,4-D followed a primary pathway of its complete reduction to phenol and a secondary pathway of sequential reductive hydrogenolysis to 2,4-dichlorophenol (2,4-DCP), chlorophenol (2-CP, 4-CP) and phenol. About 65% of 2,4-D with initial concentration of 50 μ M was transformed within 48 h in the presence of 300 mg L-1 nanoscale Fe3O4, and the reaction rates increased with increasing dosage of nanoscale Fe3O4. The decomposition of 2,4-D proceeded rapidly at optimum pH 3.0. Chloride was identified as a reduction product for 2,4-D in the magnetite-water system. Reductive transformation of 2,4-D by microscale Fe3O4 was slower than that by nanoscale Fe3O4. The reactions apparently followed pseudo-first-order kinetics with respect to the 2,4-D transformation. The degradation rate of 2,4-D decreased with the increase of initial 2,4-D concentration. In addition, anions had a significant adverse impact on the degradation efficiency of 2,4-D. [ABSTRACT FROM AUTHOR]

For the removal of 2,4-D (2,4-dichloro-phenoxy-acetic acid) and atrazine (2-chloro-4-ethyalamino-6-isopropylamino-s-traiazine) from water environment, batch studies were performed to study the kinetics of 2,4-D and atrazine sorption by rubber granules. Experiments were conducted at various initial concentrations of 7.5 mg/L, 4 mg/L, and 0.5 mg/L of 2,4-D and atrazine with 18 g/L sorbent dose. The equilibrium time was found to be 120 minutes for both 2,4-D and atrazine. The regression analysis for the experimental data showed that the rapid stage zone of kinetics profiles followed a first order reversible kinetics for all initial concentrations of sorbate. The various thermodynamic properties such as enthalpy and entropy activation values (ΔH and ΔS) also show that the sorption is spontaneous. This article will provide information toward understanding the sorption phenomena of 2, 4-D and atrazine on waste tyre rubber granules. It also is valuable to us in finding out the rate constant of sorption of 2,4-D and atrazine. [ABSTRACT FROM AUTHOR]

2,4-Dichlorophenoxyacetic acid (2,4-D) induced disparate alterations on enzymatic activities of the defensive mechanism and/or modifications of the reactive oxygen species levels in specific neonate rat brain regions. The midbrain, striatum, and prefrontal cortex were the areas where the alterations were more remarkable and with similar tendency. The hippocampus did not suffer many alterations, and the hypothalamus was the area where no changes were observed. The current results suggest that the developing brain areas have different susceptibilities to the adverse effect of the herbicide, especially those areas related to the dopaminergic system, and that oxidative stress is one 2,4-D mechanism of toxicity. [ABSTRACT FROM AUTHOR]

The effect of one organic amendment consisting of an urban waste compost (UWC) was assessed on the sorption properties of the herbicide 2,4-D on four soils of different physicochemical characteristics. The soils chosen were a Typic Haphorthod (ST), a Typic Endoaquept (SR), an Entic Pelloxerert (TO), and a Typic Eutrochrept (AL). Adsorption experiments were performed on the original soils, and on mixtures of these soils with UWC at a rate of 6.25% (w/w). These mixtures were used just after preparation, and after aging for 8 and 25 weeks. 2,4-D adsorption was the highest on ST soil, whereas the lowest adsorption was for SR soil. This behavior is related to the high amount of organic matter (OM) and amorphous iron and aluminum oxides content on soil ST, whereas soil SR had the lowest OM content and specific surface area of the soils of this study. Addition of exogenous OM to soils caused an increase in the 2,4-D adsorption by three of the soils treated with UWC, with the only exception being ST soil, due to an observed decrease in its specific surface area. The adsorbed amounts of the herbicide on aged organic fertilized soils diminished in three of the amended soils, but was still greater than on unamended soils. In contrast, the ST soil showed the largest adsorption for unamended soil. [ABSTRACT FROM AUTHOR]

Degradation of two chlorinated pesticides (2,4-D and DDT) using a 54-mL glass column packed with tezontle (a low-cost basaltic scoria) was tested. Bacteria were cultured in YPG (yeast, peptone, and glucose) liquid medium at 32°C. The rich medium was pumped during 24 h through the column to inoculate it. Later, the wasted medium was discharged and the pesticide added. Optical densities, TOC, and pesticide concentration were determined. Pesticide removals for 2,4-D (with initial concentration between 100 and 500 mg/L) were about 99%. DDT removal (at initial concentration of up to 150 mg/L) was as high as 55–99%. TOC removals for 2,4-D was in the 36-87% interval, whereas for DDT they were as high as 36–78%. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate absorption and translocation of the herbicide 2,4-D in plants of Memora peregrina. The herbicide 2,4-D was used alone with the formulation DMA 806 BR and associated with the herbicide picloram in the commercial product Padron. Levels of radioactivity on the treated leaves were determined in sample obtained after washing them with methanol and chloroform at different times after the application of the radiolabelled formulation (1,2,4,8124, and 48 h. Translocation was evaluated by cutting plants between stem and root. The parts obtained were: root, stem, leaf treated, leaves above the leaf treated, leaves below the leaf treated, and leaf opposite of the leaf treated. These parts were weighted, dried, ground, burnt, and radioactivity in the samples was determined. The results suggest that the translocation of the radioactive herbicide 24-D was insignificant in plants of M. peregrina in the two treatments evaluated. Absorption of 14C 2,4-D in the treatment with DMA 806 BR and the mixture of DMA 806 BR plus Padron had the same behavior. These observations explain the inefficient control obtained with this herbicide in plant species under study. [ABSTRACT FROM AUTHOR]

The herbicide 2,4-D is often applied as a tank mixture in combination with other herbicide products. However, current information on 2,4-D sorption by soil is largely based on batch-equilibrium experiments without considering the competition of other herbicides for sorption sites by soil. This study quantified the effect of the herbicide propanil on the sorption of 2,4-D in soil. Results indicated that propanil competed with 2,4-D for sorption sites, particularly in soils with an organic carbon content greater than 3.6% The decrease in 2,4-D sorption by soil, as a result of propanil competition, was most notably for herbicide concentrations that are typical of recommended field rates. We conclude that herbicide co-applications on agricultural fields have the potential to increase the mobility of herbicides in soil. [ABSTRACT FROM AUTHOR]