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Made available in DSpace on 2022-05-01T09:47:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-12-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Auxin-based herbicides, such as 2,4-dichlorophenoxyacetic acid (2,4-D), are lethal to plants at higher doses, but can enhance plant growth at nontoxic concentrations. The stimulating effect of low doses of a substance considered toxic is known as hormesis. This study used dose-response curves to assess the hormesis effect of low doses of 2,4-D choline salt herbicide on soybean (Glycine max (L.) Merr.) biometric variables with distinct growth habits at different phenological stages. A completely randomized experimental design with seven replicates was used, and the treatments consisted of six fractions of the average dose indicated on the label of 2,4-D choline salt formulation: 0 (control), 0.068, 0.684, 6.84, 68.4 and 684 g ae ha-1 applied at the plant’s phenological stages second node with fully developed leaves (V2) or fifth node with fully developed leaves (V5). The plants were assessed for their main biometric parameters. The results were analyzed by ANOVA and, when significant, the hormesis model was tested. The maximum effect of hormesis on the main biometric parameters of soybean plants was estimated for doses between 0.20 and 36.01 g ae ha-1 of the herbicide and varies depending on the evaluated phenological stage of the plants. Low doses of 2,4-D choline salt herbicide may increase shoots, roots and total DM when applied at stages V2 and V5 of soybean with determinate growth habit and V2 of indeterminate growth habit. There was no adjustment of the hormesis model for the soybean plant with indeterminate growth habit at stage V5. Universidade Federal de Goiás Regional Jataí, Rodovia 364, km 192 Universidade Estadual Paulista Faculdade de Ciências Agrárias e Veterinárias (FCAV), Via de Acesso Professor Paulo Donato Castellane, s/n Universidade Federal de Mato Grosso Campus do Araguaia, Avenida Valdon Varjão Universidade Estadual Paulista Faculdade de Ciências Agrárias e Veterinárias (FCAV), Via de Acesso Professor Paulo Donato Castellane, s/n

Background Environmental exposures are implicated in the etiology of amyotrophic lateral sclerosis (ALS). Application of insecticides, herbicides, and fungicides with neurotoxic properties to crops is permitted in the U.S., however reporting of the quantities is government mandated. Objective To identify pesticides that may be associated with ALS etiology for future study. Methods We geospatially estimated exposure to crop-applied pesticides as risk factors for ALS in a large de-identified medical claims database, the SYMPHONY Integrated Dataverse®. We extracted residence at diagnosis of ∼26,000 nationally distributed ALS patients, and matched non-ALS controls. We mapped county-level U.S. Geological Survey data on applications of 423 pesticides to estimate local residential exposure. We randomly broke the SYMPHONY dataset into two groups to form independent discovery and validation cohorts, then confirmed top hits using residential history information from a study of NH, VT, and OH. Results Pesticides with the largest positive statistically significant associations in both the discovery and the validation studies and evidence of neurotoxicity in the literature were the herbicides 2,4-D (OR 1.25 95 % CI 1.17–1.34) and glyphosate (OR 1.29 95 %CI 1.19–1.39), and the insecticides carbaryl (OR 1.32 95 %CI 1.23–1.42) and chlorpyrifos (OR 1.25 95 %CI 1.17–1.33). Significance Our geospatial analysis results support potential neurotoxic pesticide exposures as risk factors for sporadic ALS. Focused studies to assess these identified potential relationships are warranted.

Hybrid watermilfoil is becoming more prevalent in many lakes where the invasive Eurasian (Myriophyllum spicatum, EWM) and native northern watermilfoil (M. sibiricum) co-occur. These Eurasian and northern watermilfoil hybrids (HWM) grow 30% faster and in many cases are less sensitive to 2,4-dichlorophenoxy acetic acid (2,4-D) than either parent. The mechanism(s) impacting 2,4-D tolerance in these hybrids was investigated by comparing the absorption, translocation, metabolism, and desorption of two 2,4-D formulations in EWM and HWM.2,4-D absorption in EWM and HWM was 5.7 and 7.9 times the external herbicide concentration determined by the plant concentration factor, a metric used to determine herbicide bioaccumulation, and 2,4-D butoxyethyl ester absorption was 35.6 and 52.1 times the external concentration in EWM and HWM, respectively. Herbicide bioaccumulation was greater in HWM than in EWM. Herbicide translocation to HWM roots was limited at 192 HAT and herbicide desorption in HWM was slightly lower than EWM. No differences were found in herbicide metabolism between the two plant species.2,4-D resistance in HWM is not due to non-target-site resistance as no differences in herbicide absorption, translocation, desorption and/or metabolism were identified; therefore, target-site resistance is the most likely resistance mechanism. More research is needed to identify the molecular basis for the 2,4-D-resistant trait in HWM. © 2021 Society of Chemical Industry.

Glyphosate and 2,4-D are two herbicides commonly used together. Since there is little information about the interactions between these pesticides, the aim of this study was to evaluate the single and joint lethal toxicity of the glyphosate-based herbicide (GBH) ATANOR® (43.8% of glyphosate, isopropylamine salt) and the 2,4-D-based herbicide (2,4-DBH) Así Max 50® (602000 mg/L of 2,4-D) on Rhinella arenarum larvae. Equitoxic and non-equitoxic mixtures were prepared according to the recommendation for their combination and analyzed with a fixed ratio design at different exposure times and levels of lethality (LC10, LC50, and LC90). GBH (504h-LC50=38.67 mg ae/L) was significantly more toxic than 2,4-DBH (504h-LC50=250.31 mg ae/L) and their toxicity was time-dependent. At 48h, the equitoxic mixture toxicity was additive and from the 96h was antagonistic at LC10 and LC50 effect level. The non-equitoxic mixture toxicity was additive at LC10 effect level from the 48h to the 168h, and synergistic from the 240h. At LC50 and LC90 effect level, the mixture interaction resulted synergistic for all exposure times. This is the first study to report the synergistic interactions between GBH and 2,4-DBH on amphibians, alerting about its negative impact on aquatic ecosystems.

Sodium (Na) and arsenic (As) toxicity were monitored by hyperaccumulation of metals in Salvinia natans L. with 2,4-dichlorophenoxyacetic acid (2,4-D) induction. Salvinia was recorded with significant bioaccumulation of those metals with de-folding of cellular attributes in sustenance under toxic environment. 2,4-D priming has revised the growth components like net assimilation rate and relative water content to register initial plants' survival against Na and As. Proline biosynthesis supported in the maintenance of osmotic adjustment and plants sustained better activity through subdued electrolytic leakage. Oxidative stress due to both Na and As exposure is responsible for induction under significant moderation of lipid peroxidation and protein carbonization by 2,4-D application was evident to release the stress from metal and metalloids. Reactive oxygen species (ROS) like superoxide and hydrogen peroxide accumulation were monitored with activity of NADP(H)-oxidase. However, it was downregulated by 2,4-D to check the oxidative damages. Superoxide dismutase and peroxidases were significantly moderated to reduce the oxidative degradation for both metals with 2,4-D induction. Glutathione metabolism and recycling of ascorbate with monodehydroascorbate activity were other features to maintain the redox homeostasis for metal toxicity. At the molecular level, polymorphic variations of concern genes in redox cascades demarked significantly for those two metals and established the biomarker for those metals, respectively. As a whole, the biocompatibility of auxin herbicide in Salvinia may raise the possibility for auxin metabolism and thereby, the bioaccumulation to Na and As vis-à-vis tolerance for ecological safety is established.

Ricinus communis L. (castor bean) is valued for its oil and the performance of oil is closely related to its fatty acid composition. Thus, producing oil in vitro with favored fatty acid profiles is a promising research area and may also offer industrial opportunities. In line with this, the total amount of oil and the fatty acid composition of the samples, which were endosperm and calli obtained by treatment of various doses of plant growth regulators were determined. Results showed that the type and amount of the plant growth regulator used in the media affect the fatty acid composition. In detail, the biggest change was shown by Indole-3-Acetic Acid (IAA), in general, using the plant growth regulators at 5 mg L−1, instead of 20 mg L−1, was found to have induced larger differentiations. The effect of a natural plant growth regulator (IAA) on fatty acid profiles was bigger than the synthetic ones (NAA, 1-Naphthaleneacetic acid, and 2,4 D, 2,4-Dichlorophenoxyacetic acid). The media containing 5 mg L−1 of NAA, 20 mg L−1 of NAA, 20 mg L−1 of 2,4 D, or 5 mg L−1 of 2,4 D gave similar results.

Made available in DSpace on 2022-05-01T08:44:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Growth traits, yield, N content, photosynthetic pigments, ammonia and amino acids were measured to verify the effect of the interaction between N, Ni, and 2,4-D applied in the cotton crop. The objective was to study the hormonal effect of 2,4-D associated with the application of N and Ni in coverage to improve yield. The N (0, 40, 80, and 120 kg ha−1) and Ni(0, 300, 450, and 600 g ha−1) were applied to the soil in the square phenological growth stage. The commercial 2,4-D DMA® BR (0 and 1.8 g a.e ha−1) was applied to the leaves at the same growth stage. The supply of N in cover fertilization up to 120 kg ha−1 was beneficial for cotton, providing greater yield and content of photosynthetic pigments. The application of 2,4-D in a hormetic dose, as a synthetic auxin during the beginning of flowering, proved to be a promising technique to improve cotton yield. This end-of-cycle response is related to the requirement for auxins during the cotton fruiting process. Universidade Estadual Paulista (UNESP) Universidade do Oeste Paulista (UNOESTE) Departamento de Biologia e Zootecnia Departamento de Fitotecnia Tecnologia de Alimentos e Socioeconomia Universidade Estadual Paulista (UNESP)

Nanoflower MoS2, nanowire TiO2(NNW) and 3D MoS2/TiO2 nano-heterostructure have been synthesized successfully by simple typical hydrothermal reaction method followed by 200oC calcination under an argon atmosphere. The prepared samples are characterized in detail by XRD, FESEM, UV-vis DRS, EDX and BET. The results suggest that the TiO2 NNWis successfully coupled with MoS2 to form the heterojunction nanostructure. The hybrid heterostructures can effectively utilize visible-light and solar energy to degrade 2,4-dichlorophenoxyacetic acid (2,4-D). The degradation rate of 2,4-D is as high as 99%. The improved photocatalytic activity owes to the decreased band-gap and the heterosurface properties of MoS2/TiO2, promoting the electron-hole pairs separation and absorption capacity to visible light. This work presents a facile approach for fabricating the MoS2/TiO2 heterostructures for efficient photocatalytic 2,4-D solution, which will facilitate the development of designing photo catalysts applied in environment and energy.

The present study aimed to evaluate the Strata-X® sorbent, commonly used in cartridges, through analysis by high-performance liquid chromatography coupled with mass spectrometry. Due to the different physical-chemical characteristics of the compounds, different conditions of chromatography and mass analysis were necessary. The developed methods were validated in terms of selectivity, linear range, linearity (coefficient of determination, r2), the limit of detection (LOD), the limit of quantification (LOQ), accuracy (recovery, %), and precision (RSD, %). The results allowed us to select efficient extraction methods, using methanol acidified to pH 2 with formic acid, to elute the herbicides 2,4-D and dicamba in both sorbent materials. Besides, the Strata-X® sorbent was efficient in the sorption of analytes; thus, we indicate it for potential use in air sampling as an alternative to XAD-2.

This study aimed to determine the concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) using salting-out assisted liquid–liquid extraction (SALLE) in influent and effluent of Ahvaz water treatment plants during 2018–2019. All measured concentrations were less than the maximum allowable concentrations recommended by the National Standards Organization of Iran (1053) and WHO guidelines. The results showed that the Ahvaz treatment plant decreased the concentration of 2,4-D by 69.2%. Therefore, it is necessary to measure the persistent organic pollutants such as pesticides in different seasons, especially in autumn, winter, and spring that the chemical fertilizers and pesticides are commonly used.

Between the countless chemical substances applied in agriculture, 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide is considered as a toxic and carcinogenic pollutant which is difficult to remove from water due to its biological and chemical stability and high solubility. The goal of this study was photocatalytic degradation of 2,4-D, using Ag3PO4/TiO2 nanoparticles under visible light. The Ag3PO4/TiO2 nanoparticles were characterized using XRD, FESEM and EDS analysis to investigate its crystal structure and elemental compounds. The effect of operating parameters such as pH, contact time, catalyst dose, and initial concentration of herbicide on the efficiency of the process was studied. Increasing the pH and initial concentration of herbicide led to the reduction of the efficiency of removing the herbicide, while increasing contact time and catalyst dose increased the efficiency. The best result (98.4% removal efficiency) was achieved at pH = 3, 1 g/L catalyst dose, 60 min contact time, and 10 mg/L initial concentration of 2,4-D. According to the results, 2,4-D removal efficiency with Ag3PO4/TiO2 photocatalyst reached 96.1% from 98.4% after 5 cycles of reaction. The pseudo-first-order kinetics was the best fit for the 2,4-D degradation by Ag3PO4/TiO2 with correlation coefficients (R2 = 0.9945). The results demonstrated that the photocatalytic process using Ag3PO4/TiO2 nanoparticles in the presence of visible light had a relatively good efficiency in removing 2,4-D. Moreover, Ag3PO4/TiO2 can be used as a reusable photocatalyst for the degradation of such toxins from polluted water and wastewater. HIGHLIGHTS Photocatalytic degradation of 2,4-D by Ag3PO4/TiO2 under visible light.; Higher performance of Ag3PO4/TiO2 compared with TiO2.; High stability of the Ag3PO4/TiO2 photocatalyst after 5 cycles.; Investigation of kinetics of 2,4-D degradation.; Investigation of thermodynamics of 2,4-D degradation.

2–4 Dichlorophenoxy acetic acid is most publicly applied from chlorinated phenoxy acids herbicides. In this research, central composite design for optimization of photo-Elecro/persulfate/nZVI process to degradation and mineralization of this herbicide in aqueous solution to environment protection was applied. The initial pH (2–4), persulfate anion concentration (0.25–0.5 mg/L), direct electrical (0.5–1 A), herbicide concentration (50–100 mg/l), nZVI dose (0.05–1 mg/L), and reaction time (50–100 mg/l) are independent variables optimized. Also, the synergist effect, COD and TOC removal, the effect of radical scavengers, and by-products were investigated. The fitting of the model, suggested a quadratic model (R(2) = 0.9926). F-value and P value of ANOVA were 719.81 and 0.0001 respectivelty. After optimizing the PEP/nZVI process, the proposed optimal conditions was pH = 3.4, persulfate concentration equal to 0.49 mg/l, in 1 A direct current, nZVI dose equal to 0.1 mg/l, in 50.05 mg/l herbicide concentration as an initial concentration, in 80 min reaction time. The theoretical and actual removal was evaluated 91.99% and 92%, respectively. In the optimum condition, 45.4% synergist effect indicated. 78.3% and 66.5% of initial COD and TOC were decreased. 39.02% of Cl ion was released form 2,4-D structure. The presence of radical scavengers have an adverse impact on the performance of process. The highest amount of radical scavenging was in methanol, tert-butyl alcohol and bicarbonate ions at concentrations at 50 mM/l. The kinetic data was fitted via pseudo-first-order reaction (R(2) = 0.99).The direct and indirect oxidation process lead to formation of several organic by-products which were confirmed by GC-MS analysis.

2,4-Dichlorophenoxyacetic acid (2,4-D) is the third most applied pesticide in Brazil to control broadleaf weeds in crop cultivation and pastures. Due to 2,4-D’s high mobility and long half-life under anoxic conditions, this herbicide has high probability for groundwater contamination. Bioremediation is an attractive solution for 2,4-D contaminated anoxic environments, but there is limited understanding of anaerobic 2,4-D biodegradation. In this study, methanogenic enrichment cultures were obtained from Amazonian top soil (0—40 cm) and deep soil (50 -80 cm below ground) that biotransform 2,4-D (5 µM) to 4-chlorophenol and phenol. When these cultures were transferred (10% v/v) to fresh medium containing 40 µM or 160 µM 2,4-D, the rate of 2,4-D degradation decreased, and biotransformation did not proceed beyond 4-chlorophenol and 2,4-dichlorophenol in the top and deep soil cultures, respectively. 16S rRNA gene sequencing and qPCR of a selection of microbes revealed no significant enrichment of known organohalide-respiring bacteria. Furthermore, a member of the genus Cryptanaerobacter was identified as possibly responsible for phenol conversion to benzoate in the top soil inoculated culture. Overall, these results demonstrate the effect of 2,4-D concentration on biodegradation and microbial community composition, which are both important factors when developing pesticide bioremediation technologies. Supplementary Information The online version contains supplementary material available at 10.1007/s10532-021-09940-3.

One of the major bottlenecks in lactic acid production using microbial fermentation is the detrimental influence lactic acid accumulation poses on the lactic acid producing cells. The accumulation of lactic acid results in many negative effects on the cell such as intracellular acidification, anion accumulation, membrane perturbation, disturbed amino acid trafficking, increased turgor pressure, ATP depletion, ROS accumulation, metabolic dysregulation and metal chelation. In this review, the manner in which Saccharomyces cerevisiae deals with these issues will be discussed extensively not only for lactic acid as a singular stress factor but also in combination with other stresses. In addition, different methods to improve lactic acid tolerance in S. cerevisiae using targeted and non-targeted engineering methods will be discussed. ispartof: MICROBIAL CELL vol:8 issue:6 pages:111-130 ispartof: location:Austria status: published

Enzymatic degradation has become the most promising approach to degrading organic ester compounds. In this study, Bacillus licheniformis NCU CS-5 was isolated from the spoilage of Cinnamomum camphora seed kernel, and its extracellular lipase was purified, with a specific activity of 192.98 U/mg. The lipase was found to be a trimeric protein as it showed a single band of 27 kDa in SDS-PAGE and 81 kDa in Native-PAGE. It was active in a wide range of temperatures (5–55 °C) and pH values (6.0–9.0), and the optimal temperature and pH value were 40 °C and 8.0, respectively. The enzyme was active in the presence of various organic solvents, metal ions, inhibitors and surfactants. Both crude and purified lipase retained more than 80% activity after 5 h in the presence of commercial detergents, suggesting its great application potential in detergent industry. The highest activity was found to be towards medium- and long-chain fatty acids (C6-C18). Peptide mass spectrometric analysis of the purified lipase showed similarity to the lipase family of B. licheniformis. Furthermore, it degraded more than 90% 2,4-D butyl ester to its hydrolysate 2,4-D within 24 h, indicating that the novel lipase may be applied to degrade organic ester pesticides.

In this research work, we investigated the ability of the oxidative degradation of 2, 4-Dichlorophenoxy acetic acid herbicide via ultrasonic-assisted in electro-activation of the persulfate system in the presence of nano-zero valent iron. The effect of experimental parameters such as pH value [4–8], electrical current (0.5–1 A), persulfate concentration (0.25–0.5 mg.l(−1)), nano zero-valent iron dose (0.05–0.1 mg.l(−1)), and initial organic pollutant concentration (50–100 mg.l(−1)) on the ultrasonic-electropersulfate process performance was assessed via central composite design. The combination of ultrasonic waves with the electrochemical process to activation of persulfate showed better efficiency into 2, 4-Dichlorophenoxy acetic acid herbicide degradation compared to their implementation in individual and binary systems. Following optimal conditions (pH = 5.62, 0.80 A applied electrical current, 0.39 mg/L persulfate concentration, 0.07 mg/L nano-zero valent iron, and 50 mg/L 2,4-Dichlorophenoxy acetic acid concentration in 40 min reaction), nearly 91% removal was done. Moreover, the complete removal of 2, 4-Dichlorophenoxy acetic acid, 92% COD, and 88% TOC removal was achieved by this process near 140 min reaction. The scavenging experiment confirmed the role of free oxidizing species in the degradation of 2, 4-Dichlorophenoxy acetic acid during the process. Approximately 50% improved 2, 4-Dichlorophenoxy acetic acid removal in the process against the inclusive efficiency of single mechanisms. The obtained results were fitted to the pseudo-first-order kinetic model with a high correlation coefficient (R(2) = 0.96). Five important intermediate products of 2, 4-D oxidation were 2, 4-dichlorophenol (2, 4-DCP), 2, 6-dichlorophenol (2, 6-DCP), 4, 6 dichlororesorcinol (4, 6-DCR), 2-chlorohydroquinone (2-CHQ), and 2-chloro-1, 4-benzoquinone (2-CBQ). In the end, can be employed as a satisfactory advanced oxidation process in high mineralization of 2, 4-D and refractory organic pollutants.

Brosimum alicastrum seeds contain a high percentage of protein and essential amino acids that contribute to a proper nutrition. This tree is an alternative in the so-called crusade against hunger and its management does not involve the use of agrochemicals. The objective of this research was to evaluate the morphogenic response of foliar explants with two growth regulators, 6-Benzylaminopurine (BAP) and 2,4-Dichlorophenoxyacetic Acid (2,4-D) in the induction of calli. Results demonstrated that the combination of 1.5 mg L-1 BAP and 1 mg L-1 2,4-D (TM) and 1.5 mg L-1 BAP with 2 mg L-1 2,4-D (TN) favored callus growth in 100% of foliar explants. Calli were grown in a period of 20 d, in a culture room at 25 ± 4 °C, with 16 h of illumination. Under these conditions, calli remained in slow growth for four weeks. Those explants that generated callus were sub-cultured in fresh medium without activated charcoal. In TM and TN treatments, the multiplication of the cell mass was favored; in TN globular structures were formed. However, explants the same treatments TM and TN with activated charcoal, and under ambient 29 ± 4 °C conditions increased callus growth, but became friable at two weeks. Thus, TM and TN were the better treatments, but activated charcoal was determined to have a negative effect on callus growth.

The increasing demand for plant-derived pharmacologically active compounds calls for sustainable alternative sources and conservation of medicinal plant species. To this end, the present study investigated the development of a callogenesis protocol for Senegalia nigrescens. The plant growth regulators (PGRs), 2,4-dichlorophenoxyacetic acid (2,4-D) and thidiazuron (TDZ) at concentrations of 0.5 and 1.0 mg L−1 were tested for callus induction in the leaf, stem, cotyledon and root explants of S. nigrescens. 2,4-D was the more effective PGR across the different explant sources with 85 to 100% stem, root and cotyledon explants forming callus (EFC). Hard and compact calli with nodular structures were obtained from the stem explants, the root-derived calli were soft and moist while the cotyledon explants produced glassy and friable calli. Methanol extracts of calli obtained from the stem and root explants were characterised using fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC–MS). The FTIR spectra and GC–MS profiles revealed the presence of the four compounds evaluated, quercetin, quercetin-3-O-methyl ether, ent-kaur-15-en-18-ol and ent-kaur-15-ene-18,20-diol in both 4 and 12-week-old, root-derived calli. This study, therefore, provides preliminary information for the propagation and phytochemical harvesting in S. nigrescens.

2,4-Dichlorophenoxyacetic acid (2,4-D) is a commercially used herbicide to manage broadleaf weeds that have various toxicological and ecological effects. In view of ever-escalating use of 2,4-D, risk assessment becomes mandatory to ensure the safety of both human health and the ecosystem. Oxidative injury has been expected as a possible mechanism implicated in 2,4-D toxicity. The present study was planned and conducted to explore the antioxidant potential of selenium (Se) supplementation to moderate the 2,4-D hepatic and renal toxicity in a rat model. The rats were randomly assigned to four equal groups and treated via oral gavage for a period of 4 weeks. Group I: received deionized water as a vehicle, group II: received 2,4-D (150 mg−1 kg−1 day−1), group III: received Se supplement (1 mg−1 kg−1 day−1), and group IV: received 2,4-D (150 mg−1 kg−1 day−1) and Se supplement (1 mg−1 kg−1 day−1) simultaneously. After 4 weeks of administration, 2,4-D induced toxicity was observed, as manifested by disrupted levels of plasma urea, creatinine, alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Further, 2,4-D caused a considerable increase in tissue malondialdehyde (MDA) levels and decreased activity of antioxidant enzymes, including superoxide dismutase, catalase, and glutathione reductase. Se supplementation exhibited its antioxidant properties by significantly improving urea, creatinine, ALP, AST, and ALT, and MDA levels and antioxidant enzyme activities. In conclusion, the results suggest that 2,4-D induced hepatic and renal toxicities were attenuated by Se supplementation probably owing to its antioxidant properties.

In this work, the effect of the addition of iridium on TiO2 and Nb2O5 supports obtained by wet impregnation method was evaluated in the photocatalytic degradation of 2,4-dichlorophenoxiacetic acid under UV irradiation. The synthetized materials were analyzed by different techniques in order to determinate their physicochemical properties. In general, it was observed that the addition of iridium modifies the surface area, band gap energy and it enhances the crystallinity of the materials. Besides, an increase in the photoactivity in the degradation of the herbicide was evidenced using the materials modified. However, the Ir/TiO2 photocatalyst possess the best photocatalytic behavior toward the degradation and possible mineralization of the herbicide. The improved performance of the photocatalyst could be argued by the role of the iridium particles as electron collectors favoring the effective separation of the charge carriers and, as consequence, increasing the degradation of the molecule.

Greenhouse studies were planted at the R.R. Foil Plant Science Research Center in Starkville, MS. In the efficacy trial, pots were seeded with barnyardgrass (Echinochloa crus-galli), broadleaf signalgrass (Urochloa platyphylla), and giant foxtail (Setaria faberi). In the lab detection trial, only barnyardgrass was seeded. Both studies consisted of 16 treatments with four replications per treatment. The treatments consisted of clethodim, glyphosate, dicamba, and 2,4-D applied singularly and in combination with each other. Each herbicide combination was applied with three application methods: tank mixture, sequential applications where the synthetic auxin was applied first (auxin applied first), and sequential applications where glyphosate or clethodim was applied first (auxin applied second). The auxin applied second method had higher visual estimations of control ratings and lower biomass weights compared to the other two methods. The auxin applied second method had more glyphosate and clethodim detected with the use of liquid chromatography tandem mass spectrometry.

Several factors influence culture conditions and somatic embryogenesis responses, such as the role of plant growth regulators (PGRs) during the establishment of in vitro cultures. For instance, auxin is required for callus induction and the acquisition of embryogenic capacity in different species, but the removal of auxin is needed for the further differentiation of somatic embryos. Thus, we aimed to evaluate the effects of residual 2,4-dichlorophenoxyacetic acid (2,4-D) on the differentiation of sugarcane somatic embryos. First, embryogenic calli (EC) were separated into two groups: (a) the PGR-free group was cultured without 2,4-D, and (b) the control group was maintained on proliferation culture medium containing 2,4-D. After 21 days of culture in the dark, both groups were transferred to differentiation culture medium under light. Our results showed that calli grown in PGR-free culture medium yielded more somatic embryos and exhibited a higher accumulation of protein and starch reserves. Proteomic analysis showed a decrease in the abundance of abscisic acid (ABA)-induced proteins in the control group. The levels of residual 2,4-D and endogenous 1-aminocyclopropane-1-carboxylic acid (ACC), an ethylene precursor, were higher in the control group than in the PGR-free group. Conversely, the level of ABA was higher in the PGR-free group than in the control group. A disruption in the ABA and ethylene levels might be responsible for the observed delay in the accumulation of storage reserves in the EC of the control group, which might have affected the development of somatic embryos. Our results also showed that the efficient development of sugarcane somatic embryos appears to be preceded by efficient accumulation of storage reserves in calli, which is related to hormone homeostasis. We demonstrated that sugarcane embryogenic calli need to reduce their residual 2,4-D level to efficiently differentiate into somatic embryos.

The present study investigates the photocatalytic degradation of 2,4-Dichlorophenoxyacetic acid (2,4-D), a hazardous herbicide using TiO2/Graphene oxide nanocomposite photocatalysts. The nanocomposite photocatalysts were synthesized via solvothermal method by varying the weight percentage of graphene oxide. The nanocomposite photocatalysts were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer Emmet Teller (BET) adsorption isotherm, Fourier-transform infrared (FT-IR) and UV–visible-diffuse reflectance spectroscopy (UV–Vis-DRS) analysis. The XRD pattern of nanocomposite was found unaltered, whereas a significant change around 33–91% was observed in the surface area of nanocomposites as compared to the pristine TiO2. The UV–Vis DRS study showed a blue shift in the band edge of the composites around 21–29 nm. The complete photocatalytic degradation of 2,4-D was achieved using TiO2/GO7% catalyst within 4 h of reaction under UV-light irradiation. The photocatalytic activity of the synthesized nanocomposite photocatalysts was also compared with the standard Degussa P-25 TiO2 photocatalyst. The order of photocatalytic activity of the synthesized photocatalysts were TiO2/GO7% > P25-TiO2 > TiO2/GO5% > TiO2/GO2% > TiO2/GO1% > TiO2/GO10% > TiO2/GO0.5% > Pristine-TiO2. This study offers a better platform for the synthesis of new composite photocatalytic materials for environment abatement by the degradation of organic pollutants.

Detoxification of pesticide residues requires effective methods. In this regard, the adsorption efficiency of diethylaminoethyl cellulose (DEAE-cellulose) as an adsorbent material for the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from water at different concentrations, times, pH and temperature was evaluated comprehensively. The obtained results showed that DEAE-cellulose has greater efficacy to eliminate 2,4-D from water with a high Langmuir maximum adsorption capacity of 429.18 mg g−1 at pH 7.0. Kinetic models and thermodynamics were investigated at length. The adsorption mechanism was understood by way of electrostatic, hydrogen bonding, and Lewis acid–base type interactions. Extensive analytical characterization of the DEAE-cellulose adsorbent before and after 2,4-D adsorption was performed and liquid chromatography with a tandem mass spectrometer (LC-MS/MS) was used for the quantification of 2,4-D. The regeneration of DEAE-cellulose was achievable using dilute formic acid and the DEAE-cellulose adsorbent showed high ability in the removal of 2,4-D from the agriculture run-off water.

Controlled release formulations (CRFs) of 2,4-dichlorophenoxyacetic acid (2,4-D) with chitosan (CTS) and chitosan-starch (CTS-STA) matrices were prepared in their un-crosslinked and crosslinked forms. Pesticide-matrix interactions were probed by FT-IR, while TGA and SEM provided information on the morphological characteristics of the pesticide-loaded beads. The CRF beads are more hydrophilic at pH 4 than at pH 8 due to increased number and strength of hydrogen bonds at pH 4. Crosslinking reduces the water uptake and expansion capacity of the beads in both acidic and basic media. Swelling of both bead types in water obeys first-order kinetics. Release of 2,4-D from the beads is of the burst type which exhibits zero-order kinetics. Measured n values range from 0.32 to 0.90, indicative of a non-Fickian diffusional release mechanism controlled by both water diffusion into, and relaxation of, the beads. These characteristics predispose the matrix blends as suitable biomaterials for agricultural and environmental sustainability.

The application of plant growth regulators is a new strategy for industrial cultivation of microalgae to enhance growth performance and synthesis of bio-products. In this study, changes in some gro...

Advancement in photocatalysis is focused on large-scale commercialization where the immobilization techniques gain attention with an aim to recover and reuse the catalyst for the redemption of pollutants. TiO2 will act as a potential catalyst and chitosan, a natural biopolymer is used to immobilize TiO2. 2,4-Dicholorophenoxyacetic acid, a common broadleaf pesticide found in surface and groundwater is taken as a model pollutant. Thus, the objective is to study TiO2/chitosan beads for the degradation of 2,4-dicholorophenoxyacetic acid. TiO2/chitosan beads were prepared by the phase inversion method and studied for their morphological and physiological features. The beads were observed to be spherical in shape and X-ray diffraction analysis shows the incorporation of chitosan and TiO2. The photocatalytic degradation of 2,4-dicholorophenoxyacetic acid showed 92 % degradation for TiO2/chitosan beads in UV light. The results were also compared with bare TiO2, and extended to the continuous photocatalytic mode of degradation. The kinetics and stability of the TiO2/chitosan beads were monitored for their feasibility.

Effects of 2,4-D(2,4-dichlorophenoxy acetic acid) and Dichlorvos(2,2-dichlorovinyl dimenthyl phosphate DDVP) were investigated on soil microbial population in a 4 weeks experiment. Soil samples were serially diluted and inoculated using pour plate method on different medium and incubated at 37°C for 24 and 48 hrs for enumeration of microbial diversity, colonies that appeared on plates were counted. At pre-application of 2,4-D, bacteria had the highest population (9.5x107 Cfu), followed by fungi (7.5x105 Cfu ), actinomycetes (1.6x106 Cfu) and protozoa (1.1x103 Cfu). Likewise, the pre-application of DDVP represents the population count of microorganisms in the following manner: Bacteria (8.0x107 Cfu)>fungi (5.1x105 Cfu)>actinomycetes (1.0x106 Cfu)> protozoa (1.0x103 Cfu)f The post-application of 2,4-D and DDVP also had the similar pattern of population count. With percentage difference on each of the microbial counts, 2,4-D of bacteria, fungi, actinomycetes and protozoa (99.5%, 95.3%, 99.9% and 86.0% respectively), DDVP percentage difference (99.2%, 99.4%, 99.3% and 98.6% respectively). Application of these pesticides at recommended rates was followed by the general decline in microbial counts. Therefore, the pesticides had toxic effects on microorganisms which may be beneficial to cultivated plants.

Brazil is the largest producer of sugarcane and the world’s top pesticide market. Therefore, environmental consequences are of concern. The aim of the present study was to evaluate the acute and chronic toxicity of pesticide formulations largely used in sugarcane crops: the herbicide DMA® 806 BR (a.i. 2,4-D) and the insecticide Regent® 800 WG (a.i. fipronil), isolated and in mixture, to the Neotropical cladoceran Ceriodaphnia silvestrii. Toxicity tests with the individual formulated products indicated 48h-EC50 values of 169 ± 18 mg a.i./L for 2,4-D and 3.9 ± 0.50 µg a.i./L for fipronil. In the chronic tests, the 8d-EC50 values for reproduction were 55 mg a.i./L (NOEC/LOEC: 50/60 mg a.i./L) and 1.6 µg a.i./L (NOEC/LOEC: 0.40/0.80 µg a.i./L) for 2,4-D and fipronil, respectively. A significant decrease in reproduction of C. silvestrii in all concentrations tested of fipronil, except at the lowest, was observed. Regarding 2,4-D, the organisms had total inhibition of reproduction in the two highest concentrations. Probably your energy reallocation was focused (trade-off) only on its survival. The acute pesticide mixture toxicity (immobility) revealed a dose level dependent deviation with antagonism at low and synergism at high concentrations. For chronic mixture (reproduction) toxicity, antagonism occurred as a result of the interaction of the pesticides. Based on our results and concentrations measured in Brazilian water bodies, fipronil represents ecological risks for causing direct toxic effects on C. silvestrii. These results are worrisome given that agricultural production is likely to increase in the coming years.

Aquatic environments are constantly exposed to a cocktail of contaminants mainly due to human activities. As polluted ecosystems may simultaneously present other multiple natural stressors, the objective of the present study was to evaluate joint effect of stressors (natural and anthropogenic) on life history traits of the Neotropical cladoceran, Ceriodaphnia silvestrii. For this purpose, the effects of water conditioned with predator kairomones (fish) and environmental concentrations (sublethal) of two pesticides widely used in sugarcane monoculture in Brazil, the insecticide Regent® 800 WG (active ingredient—a.i. fipronil) and the herbicide DMA® 806 BR (a.i. 2,4-D) were evaluated using chronic toxicity testing, isolated and in mixture, for this cladoceran species. The environmental risks of pesticides for tropical freshwater biota were also estimated from the risk quotient MEC/PNEC. Among the characteristics of the life history of C. silvestrii evaluated after 8 days of exposure, compared with the mean value of control, the age of primiparous females was not affected by any evaluated treatment. However, species average survival decreased in the treatment of kairomones mixed with fipronil (FK) and in the treatment with a mixture of fipronil, 2,4-D, and kairomones (MFKD). The body length of maternal females was shorter than in the control after exposure in treatments with only kairomones (K) and FK. Fecundity of this cladoceran was reduced when exposed to FK and MFKD treatments, and the intrinsic rate of population increase significantly decreased for organisms exposed to treatment with fipronil (F) and to mixtures of fipronil and 2,4-D (MFD), MFDK, and FK. The results indicated that the combination of anthropogenic and natural stressors causes changes in C. silvestrii life history traits, which can contribute to the decline in populations, and our preliminary risk assessment results are a matter of concern regarding biota conservation.

The aim of the present study was to examine the possible protective effects of the aqueous extract of Thymus munbyanus (TMAE) against 2,4-dichlorophenoxyacetic acid (2,4-D)-induced oxidative stress...

On-site quantitative analysis of pesticide is of significant importance for addressing serious public health issues in clinical, food, and environmental settings. Herein, we designed a novel smartphone-assisted sensing platform for on-site monitoring of 2,4-dichlorophenoxyacetic acid (2,4-D) based on carbon dots/cobalt oxyhydroxide nanosheet (CDs/CoOOH) composite. In this work, a red emissive CDs/CoOOH composite was proposed as a signal indicator for shielding background interference, enhancing anti-interference capability. 2,4-D as an inhibitor of alkaline phosphatase could specifically suppress the production of ascorbic acid, which restrained in situ etching of the CDs/CoOOH composite and further triggered the fluorescence response of the biosensor. By employing a lab-on-smartphone based device and self-designed application software, the fluorescence image was directly captured and analyzed with a sensitive detection limit of 100 μg L

2,4-Dichlorophenoxyacetic acid (2,4-D) is one of the most commonly used herbicides worldwide. While the effects of 2,4-D in target organisms are well known, its consequences in nontarget organisms are not fully explained. Therefore, the purpose of this study was to investigate the effects of the herbicide on mitochondrial energy metabolism, oxidative status, and exploratory behavior in adult zebrafish. Animal exposure to 2,4-D increased cytochrome c oxidase and catalase activities and reduced SOD/CAT ratio, moreover, increased the total distance traveled and the number of crossings. Finally, animals exposed to 2,4-D spent more time in the upper zone of the tank and traveled a long distance in the upper zone. Overall, our results indicate the 2,4-D can provoke disabling effects in nontarget organisms. The obtained data showed that exposure to 2,4-D at environmentally relevant concentrations alters mitochondrial metabolism and antioxidant status and disturbs the zebrafish innate behavior.

Enantioselective biodegradation of racemic dichlorprop in two soils was investigated in the laboratory. Chiral separation of racemic dichlorprop was achieved by using HPLC with Phenomenex Lux Amylose-2. The first-order kinetic model fitted well the dissipation data of racemic dichlorprop and its pure R- and S-enantiomers. S-dichlorprop was preferentially degraded in both soils and enantioselectivity was affected by soil pH. The half-lives (DT

Abiotic stress severely threatens agriculture. Herein, we studied the effect of heteroatom-free carbon dots (CDs) on the alleviation of abiotic stresses in rice for the first time. During in vitro coincubation, suspended rice cells were exposed to 2,4-dichlorophenoxyacetate sodium (2,4-D-Na, 30 μg mL-1), 2,4-dichlorophenoxyacetic acid (2,4-D, 5 μg mL-1), NaCl (0.15 mol·L-1), and high light (2000 Lux), both with and without CDs (100 μg mL-1). After a week, CDs significantly reduced the inhibition rate of 2,4-D-Na on the rice cell biomass from 48.16 to 27.44% and increased the biomass of rice cells exposed to 2,4-D, NaCl, and high light, by 4.12, 1.10, and 4.01 times that of the control (pure nutrient medium), respectively. Furthermore, the growth of CD-germinated rice seedlings was not obviously affected by 2,4-D-Na, 2,4-D, and NaCl. Further results showed that the CDs demonstrated an intrinsic free-radical scavenging property and could increase the peroxidase activity and the contents of phenolics and flavonoids in rice by 125.81, 39.60, and 47.63%, respectively. Furthermore, CDs improved the nutrient assimilation of rice cells under 2,4-D stress by 14.69%. With higher antioxidant capacity and sufficient nutrients, the CD-treated rice showed excellent resistance to abiotic stresses. This study suggested the great potential of CDs in protecting crops against abiotic stress.

We show a possibility of the spectrophotometric determination of 2,4-dichlorophenoxyacetic acid based on the extraction of its ion pair (IP) with polymethine dye Astrafloxin FF with toluene. The maximum recovery of the ion pair from the aqueous phase is achieved at pH 6–11 and a dye concentration of (1.6–2.8) × 10–4 M. The conditional molar absorption coefficient of the ion pair is 4.0 × 104, and the limit of detection for 2,4-dichlorophenoxyacetic acid is 0.9 µg/mL. The developed method of the extraction–spectrophotometric determination of 2,4-dichlorophenoxyacetic acid was used to analyze water and herbicides.

2,4-Dichlorophenoxyacetic acid (2,4-D) is a typical chlorinated aromatic herbicide which is widely used because of its low cost. Herein, a new fluorescent assay for 2,4-D is developed based on covalent organic frameworks (COFs) and MnO2 nanosheets. The fluorescence of COFs is quenched effectively by MnO2 nanosheets. Ascorbic acid 2-phosphate (AAP) is hydrolyzed by alkaline phosphatase (ALP) to produce ascorbic acid (AA), which reduces MnO2 nanosheets into Mn2+, so the quenched fluorescence recovers. Additionally, 2,4-D can inhibit the catalytic activity of ALP. Therefore, the addition of 2,4-D quenches the fluorescence of COF-MnO2 system again. Under the optimum conditions, this assay displays a wide linear range of 2,4-D from 1 to 150,000 ng/mL with a limit of detection of 0.36 ng/mL. Then, this method is successfully used to measure 2,4-D in rice, millet, and cucumber samples with satisfactory recoveries. Compared with other probes for 2,4-D detection, both of COFs and MnO2 nanosheets are stable, cost-effective, and easily prepared. The sensitivity and linear range of 2,4-D in this strategy are superior to most reported works. This is the first time that a novel sensing platform using fluorescent COFs and MnO2 nanosheets is developed for 2,4-D.

Common blue violet is a widely distributed, perennial broadleaf that is difficult to control in lawns. Two experiments were conducted to evaluate the efficacy of synthetic auxin herbicides and their mixtures or rate for common blue violet control. A herbicide comparison experiment was conducted with treatments including a nontreated check; 2,4-D dimethylamine; 2,4-D isooctyl ester (2,4-D ester); dichlorprop (2,4-DP) ethylhexyl ester, MCPA dimethylamine; mecoprop dimethylamine; triclopyr butoxyethyl ester; quinclorac; and mixtures of triclopyr + quinclorac; 2,4-D ester + 2,4-DP; 2,4-D ester + triclopyr; 2,4-D ester + 2,4-DP + triclopyr. All herbicides were applied at 1.12 kg ae ha–1 except quinclorac (0.84 kg ha–1). Additionally, a triclopyr dose-response experiment was conducted using rates of 0, 0.14, 0.28, 0.56, 0.84, and 1.12 kg ha–1. Epinasty ranged from 80% to 99% at 21 d after application for triclopyr-containing treatments and no more than 28% for all other treatments. Plant mass from harvest and regrowth data from the comparison experiment indicated triclopyr-containing treatments provided the highest common blue violet control. Mixtures containing triclopyr did not differ from triclopyr alone, indicating there was no added effect between herbicide mixtures. The triclopyr dose-response experiment confirmed triclopyr efficacy across data collection types. As triclopyr dose increased, violet epinasty increased and chlorophyll content and dry weight decreased. Triclopyr applied at 0.81 kg ha–1 or greater concentration provided 75% or greater control, as indicated by regrowth data. Many herbicides containing triclopyr are registered for use in turf, but most apply a concentration not greater than 0.56 kg ha–1 triclopyr when applied at the high label rate. Thus, to achieve good (75%) common blue violet control, turf managers should select products that contain triclopyr and apply doses of at least 0.81 kg ha–1 when used according to the label.Nomenclature: 2, 4-dichlorophenoxyacetic acid; (±)-2-(4-chloro-2-methylphenoxy)propanoic acid (mecoprop); (±)-2-(2, 4-dichlorophenoxy) propanoic acid (dichlorprop); 2, 4-D dimethylamine; 2, 4-D isooctyl ester; 4-chloro-2-methylphenoxyacetic acid; 3, 7-dichloro-8-quinolinecarboxylic acid (quinclorac); 3, 5, 6-trichloro-2-pyridinyloxyacetic acid (triclopyr); common blue violet; Viola sororia Willd. VIOPP.

The article describes the study on the effectiveness of remedies possessing antioxidant properties for chemoprevention of the consequences caused by pesticides toxic effects. 2,4-dichlorophenoxyacetic acid derivatives, and namely, amine salt of 2,4-dichlorophenoxyacetic acid are known as one of the most widely distributed compounds in agriculture. The activation of the free radical processes is considered as a universal mechanism of the damage to biological membranes during chronic intoxication by phenoxyacid derivatives. This work is aimed to compare the preventive effect of the synthetic and natural antioxidants under long-term exposure to the 2,4 - dichlorophenoxyacetic acid. The experiment was performed on Wistar male rats, which received synthetic and natural antioxidants against the background of toxicant administration. Long-term effects of the pesticide caused the activation of the processes of free radical lipid peroxidation, reduced antioxidant supply and activity of antioxidant enzymes. The introduction of medicines with antioxidant properties helped to reduce the content of products of free radical processes, to inhibit the drop of body antioxidant supply and to normalize the activity of antioxidant enzymes. According to the experimental data obtained, the complex of natural antioxidants (tocopherol acetate, ascorbic acid and quercetin) has the most pronounced corrective properties. This enables us to recommend them for chemocorrection of pathological changes resulted from prolonged exposure to pesticides.

In the present study, Fe3O4@TiO2/Cu2O nanocomposites were synthetized and supported on granular activated carbon (GAC). The synthesized nanocomposite coated on GAC was used as catalyst in photocatalytic process for 2,4-dichloropenoxyacetic acid (2,4-D) removal from aqueous solutions. The coated nanocomposite was characterized using XRD, TEM, BET, VSM, UV–Vis DRS, SEM and EDX tests to evaluate its surface morphology and elemental compounds. Results indicated that the photocatalytic efficiency for the removal of 2,4-D was reduced with increasing solution pH, and the maximum removal efficiency was obtained at solution pH of 5. The photocatalytic efficiency was increased with increasing catalyst dosage from 0.1 to 0.4 g/L. The results implied that reaction temperature played a key role in the photocatalytic performance and the process efficiency increased with increasing reaction temperature in the range of 10–35 °C. The kinetic study showed that the photocatalytic process followed the first-order kinetic model. Moreover, in the photocatalytic process, ·OH acted as the main agent for the oxidation of 2,4-D. According to the results, Fe3O4@TiO2/Cu2O magnetic nanocomposite supported on GAC offered a suitable performance after five cycles, and therefore, it can be used as a reusable and cost-effective catalyst for removing such toxins from polluted waters.

3D polymer nanomagnetic (3D/GO/Fe3O4) adsorbent was fabricated and used for determining removal of 2,4-D from an aqueous solution. The adsorbent was characterised by FTIR, XRD, FE-SEM, TEM, VSM, an...