Concentrations Of Trifluralin Research Articles

A simple AIE probe to pesticide trifluralin residues in aqueous phase: Ultra-fast response, high sensitivity, and quantitative detection utilizing a portable platform

The threat from pesticide trifluralin residues to ecological environment and public health is becoming a growing problem. Thus, rapid and sensitive detection, particularly a simple and portable detected platform for trifluralin residues, are highly desired. Here, a small organic aggregation-induced emission (AIE) molecule (TPETPy) is facilely synthesized and applied to detect trifluralin both in lab and in actual water systems. Based on the photo-induced electron transfer (PET) mechanism, the emissive peak of TPETPy located at 475 nm in tetrahydrofuran (THF)/water mixture (ƒw = 90 %) under the excitation of 340 nm, decreases dramatically upon trace trifluralin addition and exhibits ultra-fast response (3 s), high sensitivity and selectivity, and good anti-interference ability. The fluorescence sensing correlation with the concentration of trifluralin shows good linearity in the range of 20–90 μg L−1 with the limit of detection of 6.28 μg L−1. Moreover, a portable smartphone-integrated detected platform based on fluorescent pattern Red/Green/Blue (RGB) values is first employed to realize the real-time and on-site quantitative fluorescent detection of trifluralin in actual water sources, featuring good accuracy and reproducibility. Hereby, this work provides not only a highly efficient trifluralin residues fluorescent probe but also a portable and straightforward operating platform to detect trifluralin pesticides quantitatively.

Catalytic electrodes’ characterization study serving polluted water treatment: environmental healthcare and ecological risk assessment

Pesticide residues in the environment have irreparable effects on human health and other organisms. Hence, it is necessary to treat and degrade them from polluted water. In the current work, the electrochemical removal of the fenitrothion (FT), trifluralin (TF), and chlorothalonil (CT) pesticides were performed by catalytic electrode. The characteristics of SnO2-Sb2O3, PbO2, and Bi-PbO2 electrodes were described by FE-SEM and XRD. Dynamic electrochemical techniques including cyclic voltammetry, electrochemical impedance spectroscopy, accelerated life, and linear polarization were employed to investigate the electrochemical performance of fabricated electrodes. Moreover, evaluate the risk of toxic metals release from the catalytic electrode during treatment process was investigated. The maximum degradation efficiency of 99.8, 100, and 100% for FT, TF, and CT was found under the optimal condition of FT, TF, and CT concentration 15.0 mg L−1, pH 7.0, current density 7.0 mA cm−2, and electrolysis time of 120 min. The Bi-PbO2, PbO2, and SnO2-Sb2O3 electrodes revealed the oxygen evolution potential of 2.089, 1.983, 1.914 V, and the service lifetime of 82, 144, and 323 h, respectively. The results showed that after 5.0 h of electrolysis, none of the heavy metals such as Bi, Pb, Sb, Sn, and Ti were detected in the treated solution.

Enhanced electrocatalytic elimination of fenitrothion, trifluralin, and chlorothalonil from groundwater and industrial wastewater using modified Cu-PbO2 electrode

In this study, fenitrothion (FTH), trifluralin (TRL), and chlorothalonil (CHT) pesticides were studied as simultaneous degradation candidates for the anodic oxidation (AO) process. Characterization experiments including FE-SEM, XRD, cyclic voltammetry, electrochemical impedance spectroscopy, linear polarization, and accelerated service lifetime test (ASLT) were performed to evaluate the effect of Sn@Sb, PbO2, and PbO2/Cu electrodes. The doping of Cu into PbO2 electrode played an important role in improving the electro-catalytic activity of the electrode and can further increase the •OH generation capacity. Simultaneous removal FTH, TRL, and CHT using the AO process was optimized by response surface methodology. Analysis of variance revealed that the R2 of removal efficiency for FTH, TRL, and CHT were 0.9848, 0.9791, and 0.9770, respectively. Moreover, the adjusted R2 for degradation of FTH, TRL, and CHT were 0.9822, 0.9756, and 0.9738, and the predicted R2 were 0.9770, 0.9694, and 0.9685, respectively. The complete removal efficiency for FTH, TRL, and CHT was achieved under the optimal condition including FTH concentration 8.0 mg L−1, TRL concentration 12.0 mg L−1, CHT concentration 16.0 mg L−1, pH 6.0, current density 6.0 mA cm−2, and oxidation time of 60 min. In the optimum condition COD removal efficiency and energy consumption were 74.3% and 4.4 kWh m−3 using PbO2/Cu electrode, respectively. The kinetic of FTH, TRL, and CHT degradation on Sn@Sb, PbO2, and PbO2/Cu electrodes best fitted on a pseudo-first-order kinetic model. The oxygen evolution overpotential was 1.914, 1.983, and 2.138 V vs. SCE for Sn@Sb, PbO2, and PbO2/Cu electrodes, respectively. The ASLT of PbO2/Cu electrode is 344 h, which is 2.3 and 4.2 times longer than that of PbO2 and Sn@Sb electrodes. The degradation mechanism was evaluated using GC–MS technique and a possible degradation pathway for the anodic oxidation of FTH, TRL, and CHT was proposed based on the identified intermediates. As a result, the AO technology using PbO2/Cu electrode could be considered a nice solution to the treatment of pesticides-polluted wastewater.

Acute Toxicity, Oxidative Stress, Toxicity Mechanism, and Degradation Dynamics of Trifluralin in Eisenia foetide (Annelida: Lumbricidae)

Abstract Trifluralin is a preemergent herbicide that is applied to soil to control annual grasses and broadleaf weeds. It is widely used in cotton, Gossypium hirsutum L., production in China; however, the ecological safety of its continued use is a controversial issue. We studied the interaction of trifluralin and earthworms, Eisenia foetide Savigny (Annelida: Lumbricidae), to provide additional information for assessing the risk of trifluralin to ecological safety in soils. Contact toxicity assays established median lethal concentrations (LC50) of 726.298 µg/L at 24 h, 418.783 µg/L at 48 h, and 82.007 µg/L at 72 h of exposure to trifluralin. Within 24 to 48 h of exposure to trifluralin, antioxidant activity (e.g., superoxide dismutase, catalase, peroxidase) increased in vivo, but by 72 h of exposure the activity was inhibited and, at high concentrations of trifluralin, death occurred. Based on the activity of glutathione S-transferase (GST) and multifunction oxidase (MFO), it appears that GSTs may be involved in the detoxification of trifluralin in vivo, and that MFOs may be the key detoxification enzymes involved. Earthworm degradation of trifluralin shortened the half-life of trifluralin in soil by as much as 1.78 d. These results provide useful information on the toxicity mechanism of trifluralin in earthworms, the role of earthworms in trifluralin degradation, as well as the ecological safety of trifluralin.

Simultaneous electrochemical degradation of pesticides from the aqueous environment using Ti/SnO2–Sb2O3/PbO2/Bi electrode; process modeling and mechanism insight

In this work, modified Bi–PbO2 electrode was fabricated and employed for simultaneous degradation of fenitrothion (FT), trifluralin (TF), and chlorothalonil (CT) from synthetic and pesticide wastewater through the anodic oxidation process. A novel high-performance liquid chromatography method was developed and optimized to identify the pesticides simultaneously. Quadratic models were developed to investigate the effects of main operating parameters and predict the degradation efficiencies of the treatment processes. The R2 of the degradation efficiencies were obtained of 0.9847, 0.9910, and 0.9821 for FT, TF, and CT, respectively, which indicates the degree of conformity between the experimental and the actual values of degradation efficiencies, and the adjusted R2 values for the degradation efficiency of FT, TF, and CT in proposed models were 0.9826, 0.9898, and 0.9796, and the values of the predicted R2 were 0.9792, 0.9875, and 0.9755, respectively. The maximum degradation efficiencies of 99.7, 100, and 100% obtained for FT, TF, and CT, respectively, under the optimal operating condition of FT, TF, and CT concentration of 10.0, 6.0, and 8.0 mg L−1, respectively, pH 6.0, the current density 6.0 mA cm−2, and electrolysis time of 60 min. Chemical oxygen demand removal and energy consumption were 64.7% and 5.1 kWh m−3. Eventually, the generated intermediates and other produced species of pesticides through the treatment process was evaluated using a gas chromatography–mass spectrometry method, and their degradation pathways were proposed.

Trifluralin residues in soils from main cotton fields of China and associated ecological risk

Trifluralin is a widely used dinitroaniline herbicide in cotton fields of China but is highly persistent in the environment and can act as a biotoxin and cause genotoxicity to terrestrial organisms, including humans. In this study, the concentrations and distribution of trifluralin residues in 139 soil samples from the major cotton-producing areas of China were investigated. The trifluralin concentrations ranged from ND (not detected) to 66.39 μg/kg dry weight (dw), with a geometric mean of 4.13 μg/kg dw. The detection frequency of trifluralin in Hebei (75%) was higher than that in Xinjiang (66%) and Shandong (40%), but the mean trifluralin concentration was highest in Xinjiang (5.98 μg/kg dw), followed by Hebei (5.06 μg/kg dw) and Shandong (3.19 μg/kg dw). No trifluralin residues were detected in cotton soil in Anhui, Jiangxi and Hunan. The residual amount of trifluralin in soil was significantly correlated with the soil organic matter content. The risk quotient method was used to evaluate the ecological risks associated with trifluralin. Results indicated that trifluralin in all the samples had a low risk to earthworms, but trifluralin in same cotton soils showed high risks to wheat, barley and lucerne. Overall, our work is helpful to understand the residual situation of trifluralin in Chinese cotton soil, to assess the environmental risk of trifluralin, and to control the use and safety of trifluralin in cotton field cultivation.

Photocatalytic Degradation of Trifluralin in Aqueous Solutions by UV/S2O82− and UV/ZnO Processes: A Comparison of Removal Efficiency and Cost Estimation

Trifluralin is one of the most widely used herbicides, being accounted as the cause of cancer in human. In the present research, the UV/S2O82− and ZnO/UV processes’ efficiency in the removal of trifluralin was investigated. A lab scale equipped with a UV lamp was applied. The parameters were studied, including initial trifluralin concentration (0.4–1.2 mg/L), contact time (20–60 min), S2O82− concentration (20–60 μM), and ZnO concentration (50–150 mg/L). The remained trifluralin concentration was measured by HPLC. This study proved the trifluralin removal of 92.90 ± 1.6% and 87.91 ± 19.22% for UV/S2O82− and UV/ZnO processes in the best operation conditions (contact time of 60 min, the persulfate concentration of 40 μM, and the ZnO concentration of 100 mg/L). The optimal trifluraline concentrations were 1.2 mg/L and 0.6 mg/L for UV/S2O82− and UV/ZnO processes, respectively. In both processes, the removal efficiency of trifluralin increased significantly with increasing contact time. The findings exhibited that both processes UV/S2O82− and UV/ZnO followed the zero-order kinetic. The electrical energy consumed of UV/S2O82 and UV/ZnO was about 43.95 and 20.41 Kwh/kg, respectively. The results show that UV/S2O82− and ZnO/UV processes were appropriate as the effective treatment method for trifluralin removal. Therefore, it is proposed to study the performance of these processes as an environmentally friendly practice in full scale with real wastewater.

The Effect of Trifluralin on Post-in vitro Morphogenesis of Five Genotypes of Head Cabbage (Brassica oleraceae var. capitata)

Abstract Six genotypes of head cabbage (‘Flexima’, ‘Mutsuma’, ‘Septima’, ‘Zeus’, DC6, ‘Ancoma’) have been studied to find an effective method of obtaining polyploids using trifluralin. The effect of various trifluralin concentrations (0.5, 1.0, 1.5, and 2.0 mg·L−1) and treatment conditions (24 °C/24 h, 24 °C/48 h, 30 °C/24 h, and 30 °C/48 h) on organogenesis of organogenic callus, hypocotyl, and seeds was tested. Ploidy level was detected using a flow cytometer. As a result, low survival of hypocotyls and calli was obtained. The shoots induced from calli and hypocotyls failed to develop quality plantlets and most calli and hypocotyls remained recalcitrant for further differentiation. Treated seeds seemed to be promising objects basing on a considerable percentage of plant regeneration. With the increased concentration of trifluralin and increasing press of treatment conditions, the seed germination rate was significantly reduced. Shoot induction from germinated seeds varied among genotypes and treatments. The root induction was independent of treatments but also reduced considerably compared to the control. Under tested conditions, none of the polyploids resulted. Further studies are required to be successful in protocol development.

Facile synthesis of an aggregation-induced emission (AIE) active imidazoles for sensitive detection of trifluralin

A novel imidazoles fluorescent probe (2) was synthesized from vanillin, o-phenylenediamine, and N,N-diphenylcarbamyl chloride. Its structure was characterized by fluorescence spectra, UV–Vis spectra, 1H NMR, 13C NMR, and high-resolution mass spectrometry (HRMS). Moreover, its aggregation-induced emission (AIE) feature was investigated in THF/MeOH solution. Furthermore, the fluorescence quenching experimental results suggest that compound 2 is the potential fluorescent probe of small organic molecules showing high selectivity and sensitivity for nitroaromatic compounds. In addition, the probe could be applied in the determination of trifluralin with fast response and stability. The fluorescence response of the probe exhibited a good linear correlation with the concentration of trifluralin ranging from 10 to 100 μM, and the limit of detection (LOD) was as low as 5.066 μM. Finally, the probe was successfully utilized to determine the amount of trifluralin in real samples, and the recoveries were 91.1% to 111.2%, indicating the applicability and reliability of the probe.

Genome re-diploidization occurs spontaneously just prior to anthesis in artificially induced auto-tetraploid maize (Zea mays L.) inbred lines

In this study, various concentrations of oryzalin (0, 5, 10, 50, and 100 mg l−1), trifluralin (0, 5, 10, 50, and 100 mg l−1), and colchicine (0, 250, 500, 1000, and 5000 mg l−1) each for 12, 24, or 48 h were tested on auto-tetraploid production in Zea mays L. inbred lines "S61" and "K1263/17". The highest rates of tetraploids were obtained in the inbred line "S61" following 50 mg l−1 oryzalin for 24 h (11.1%) and colchicine treatment at 1000 mg l−1 for 24 h (12.2%) and 48 h (15.8%). In the inbred line "K1263/17", tetraploids were detected with trifluralin at 10 mg l−1 (2.3%) and 50 mg l−1 (6.9%) both for 24 h. High rate of tetraploid production (19.5%) was also observed in the presence of 1000 mg l−1 colchicine for 24 h. Compared to their diploid counterparts, the regenerated tetraploids exhibited relatively lower survival rate, and only 33.3% of the inbred line "K1263/17"-derived tetraploids survived and developed. Moreover, all survived regenerants kept their altered ploidy level until the seventh-leaf stage, and then turned the ploidy level back to the diploid state prior to the anthesis. Except for plant height, basal stem diameter, and total chlorophyll content of the seventh leaves, the diploid and re-diploidized tetraploids were not significantly different in terms of other morphological features assessed. Although it was possible to induce polyploidy in Z. mays L., the auto-tetraploids re-diploidized their genome simultaneously before anthesis, offering a precious platform to study the mechanism of genome downsizing in greater detail in this species. Auto-tetraploids can be induced in Zea mays L. using colchicine and dinitroaniline herbicides. The generated tetraploids either die or downsize their genome prior to anthesis.

Persistence of atrazine and trifluralin in a clay loam soil undergoing different temperature and moisture conditions.

Dissipation kinetics of atrazine and trifluralin in a clay loam soil was investigated in a laboratory incubation experiment under different temperature and moisture conditions. The soil was spiked with diluted atrazine and trifluralin concentrations at 4.50 and 4.25mg/kg soil, respectively, the moisture content adjusted to 40, 70, and 100% of field capacity (FC) and then incubated in three climatic chambers at 10, 20, and 30°C. For each of the herbicides, soil samples were collected at 0, 7, 21, 42, 70, and 105 days and analysed by Gas Chromatography-Electron Capture Detector (GC-ECD). A stochastic gamma model was used to model the dissipation of herbicides from the clay loam soil by incorporating environmental factors as covariates to determine half-life and days to complete dissipation. Results showed that temperature played a greater role on atrazine persistence than soil moisture; while the interaction effect of temperature and moisture was significant on the persistence of trifluralin over time. Atrazine dissipated more rapidly at 30°C compared to 10 and 20°C, with a half-life of 7.50 days and 326.23 days to reach complete dissipation. Rapid loss of trifluralin was observed at 70% moisture content when incubated at 30°C, with a half-life of 5.80 days and 182.01 days to complete dissipation. It was observed that the half-life of both herbicides tended to double with every 10°C decreases of temperature over the range tested. The model indicated that both atrazine and trifluralin have the potential to persist in clay loam soil for several years at temperature ≤20°C; which could potentially affect following crops in rotation.

The use of trifluralin to control fungal infection and to increase hatching rate of fertilized eggs of brood ship sturgeon (Acipenser nudiventris) in Guilan Province

A brood ship sturgeon with the weight of 10 kg, produced 3.6 kg eggs. After the fertilization process, 300 g of eggs (approximately 8800±120 eggs) were distributed into each box of Youchtchenko incubator (each incubator has 4 boxes). The research was carried out with 4 treatments and 3 replications in each treatment. The research was conducted at the International Sturgeon Research Institute and Beheshti Sturgeon Restoration and Genetic Conservation Center, in 2017. Treatments included control (no added trifluralin herbicide) and 3 different concentrations of trifluralin, treatment 1 (0.1 mg L-1), treatment 2 (0.05 mg L-1), treatment 3 (0.025 mg L-1). Trifluralin was added 24 hours after placing the fertilized eggs in the incubator. 48 hours after incubation, the number of fungal eggs reached the highest level in treatments. However, in the control treatment it was significantly more than other treatments) p<0.05(. In treatments 2 and 3 the remaining eggs and the hatching rate, were significantly lower than other treatments) p<0.05(. Possibly, the use of trifluralin in two concentrations of 0.025 and 0.05 mg L-1 had negative effects, which may be due to low concentrations and use as a temporary bath. After 96 hours, the eggs were completely hatched. Hatching rate in treatment 1, was significantly more than control and treatments 2 and 3 (p<0.05). The results indicated that trifluralin can be successfully used in the proper function of Youchtchenko incubator, at a concentration of 0.1 mg L-1.

Cross-Taxa Distinctions in Mechanisms of Developmental Effects for Aquatic Species Exposed to Trifluralin.

Standard ecological risk assessment practices often rely on larval and juvenile fish toxicity data as representative of the amphibian aquatic phase. Empirical evidence suggests that endpoints measured in fish early life stage tests are often sufficient to protect larval amphibians. However, the process of amphibian metamorphosis relies on endocrine cues that affect development and morphological restructuring and are not represented by these test endpoints. The present study compares developmental endpoints for zebrafish (Danio rerio) and the African clawed frog (Xenopus laevis), 2 standard test species, exposed to the herbicide trifluralin throughout the larval period. Danio rerio were more sensitive and demonstrated a reduction in growth measurements with increasing trifluralin exposure. Size of X. laevis at metamorphosis was not correlated with exposure concentration; however, time to metamorphosis was delayed relative to trifluralin concentration. Gene expression patterns indicate discrepancies in response by D. rerio and X. laevis, and dose-dependent metabolic activity suggests that trifluralin exposure perturbed biological pathways differently within the 2 species. Although many metabolites were correlated with exposure concentration in D. rerio, nontargeted hepatic metabolomics identified a subset of metabolites that exhibited a nonmonotonic response to trifluralin exposure in X. laevis. Linking taxonomic distinctions in cellular-level response with ecologically relevant endpoints will refine assumptions used in interspecies extrapolation of standard test effects and improve assessment of sublethal impacts on amphibian populations. Environ Toxicol Chem 2020;39:1797-1812. Published 2020. This article is a US government work and is in the public domain in the USA.

Trifluralin and Atrazine Sensitivity to Selected Cereal and Legume Crops

Soil-applied herbicides can persist in sufficient concentrations to affect the growth of crops in rotations. The sensitivity of wheat, barley, oat, lucerne and lentil to trifluralin and atrazine residues were investigated with three glasshouse experiments in 2018 and 2019. Each bioassay crop species was tested against different concentrations of trifluralin and atrazine in sandy soil using a full factorial design. Shoot and root parameters of the tested crop species were fitted in logistic equations against herbicide concentrations to calculate effective doses for 50% growth inhibition (ED50). Results revealed that both shoot and root parameters of all the test crop species were significantly affected by trifluralin and atrazine. Trifluralin delayed crop emergence at the lower concentrations examined, while higher concentrations prevented emergence entirely. Low concentrations of atrazine did not affect emergence but significantly reduced plant height, soil–plant analyses development (SPAD) index, shoot dry weight, root length, root dry weight and number of nodules of all the crop species. At high concentration, atrazine resulted in plant death. Legumes were found to be more sensitive than cereals when exposed to both trifluralin and atrazine treatments, with lucerne being the most sensitive to both herbicides, ED50 ranging from 0.01 to 0.07 mg/kg soil for trifluralin; and from 0.004 to 0.01 mg/kg for atrazine. Barley was the most tolerant species observed in terms of the two herbicides tested. Lucerne can be used to develop a simple but reliable bioassay technique to estimate herbicide residues in the soil so that a sound crop rotation strategy can be implemented.

Morphological, anatomical, physiological, and cytological studies in diploid and tetraploid plants of Plantago psyllium

Plantago psylliumis is under development as the source of mucilage, but has not been entirely domesticated. Since mucilage content is low and variable in the medicinal plant, it is imperative to apply breeding approaches to accelerate the domestication process and improve the mucilage content in the seeds. One approach to achieve these purposes is polyploidy induction, which can increase the size of plants and their phyto-medicines. To conduct this approach and evaluate the effect of in vitro-induced polyploidy on different traits of P. psylliumis, a gradient of colchicine concentrations, 0.1, 0.3 and 0.5% (w/v), was used to treat the terminal buds for 6, 12 and 24 h. The terminal buds were separately treated with different trifluralin concentrations, 7.5, 15 and 22.5% (w/v), for 12, 24 and 48 h. The optimal treatments of 0.5% colchicine for 24 h, and of 22.5% (w/v) trifluralin for 72 h resulted in an induction efficiency of 23% and 19%, respectively. Chromosome counting revealed successful chromosome duplication in tetraploids (2n = 4x = 24), in contrast with intact diploids (2n = 2x = 12). Duplication of DNA size in tetraploids was also proved by flow-cytometry analysis. The tetraploids size was larger than their intact diploids for spike, seed and pollen grain, leaf thickness, and plant height. The stomata of tetraploids were larger with lower density than diploids. The chloroplast number in guard cells, along with chlorophyll and carotenoid content all were higher in tetraploids. In final, our study suggests that tetraploidization could be useful to improving the seed mucilage content for commercial use. We firstly fulfilled the in vitro induced tetraploidy in P. psyllium by 0.5% colchicine for 24 h and 22.5% (w/v) trifluralin for 72 h, and improved the mucilage content in the seeds.

Acute Toxicity of Herbicides on the Survival of Adult Shrimp, Artemia Franciscana

Background: Herbicides are widely used in agriculture to kill a large variety of unwanted weeds. However, the application in water ecosystems may pose harmful impacts on the health of aquatic organisms. We studied the acute toxicity of four major types of herbicides on the survival of adult shrimp, Artemia franciscana (AF). Methods: The brine shrimp, AF, was hatched from the commercially encysted dry eggs. The acute toxicity (LC50; 48 hr) of four herbicides, paraquat; 2,4-dichlorophenoxy acetic acid (2,4-DCPA); trifluralin; and glyphosate, was examined by a standard method. We exposed the shrimps to sequentially rising concentrations of each herbicide in triplicate. The mortalities were recorded at 12, 24, 36, and 48 hours after exposure and the LC50 was calculated, using a Probit software. Results: This study demonstrated that the acute toxicity of these herbicides was significantly different in adult shrimp AF. The lethal concentrations (LC50) of Paraquat, 2,4-DCPA, trifluralin and glyphosate against the shrimp were 2.701, 14.475, 0.446 and 17.431 mg/l, respectively. Trifluralin and paraquat caused the highest lethality at lower LC50 concentration compared to the other two herbicides. Conclusion: The results demonstrated that increasing herbicides concentration or duration of exposure raised the mortality rate of AF’s.

Improved chromosome doubling of parthenogenetic haploid plants of cucumber (Cucumis sativus L.) using colchicine, trifluralin, and oryzalin

An effective chromosome doubling protocol was established in essential garden crop of cucumber (Cucumis sativus L.) Cv. Hi Power. The different concentrations of colchicine (0, 250, 500, 750, and 1500 mg/L), oryzalin (0, 5, 15, 25, 50, 75, and 150 mg/L) and trifluralin (0, 5, 15, 25, 50, 75, and 150 mg/L) were applied on parthenogenesis-induced haploid nodal and shoot tip explants of cucumber for 18 and 38 h in three independent factorial experiments. Increasing concentrations of applied antimitotic agents led to the significant reduction in the survival rate of both shoot tip and nodal explants, especially in longer exposure duration. Three ploidy levels including haploid, mixoploid, and doubled haploid were regenerated form both explant types treated with colchicine, oryzalin, and trifluralin. Flow cytometry analysis proved successful chromosome doubling of haploid plants. Based on the results obtained, the highest number of regenerated doubled haploid plants (92.31%) and fruit set (86.21%) were related to immersion of nodal explants in 50 mg/L oryzalin for 18 h. The highest doubled haploid regeneration for colchicine and trifluralin antimitotic agents were 58.33 and 83.33%, respectively. The leaf size of doubled haploid plants was larger than their correspond haploids. The optimized chromosome doubling protocol would be applicable for doubled haploid production in garden crops of Cucurbitaceae family, which is recalcitrant to the spontaneous doubling, and also for in vitro polyploidy induction studies.

Effects of three pesticides on superoxide dismutase and glutathione-S-transferase activities and reproduction of Daphnia magna

Abstract Applying pesticides to crops is one of the causes of water pollution by surface runoff, and chlorpyrifos, trifluralin and chlorothalonil are used respectively as insecticide, herbicide and fungicide for crop plants widely. To explore effects of three pesticides on aquatic organisms, superoxide dismutase (SOD) and glutathione S-transferase (GST) activities were determined after 24 h and 48 h exposure of D. magna with ages of 6–24 h to several low concentrations of chlorpyrifos (0.36, 0.72, 1.43, 2.86, 5.72 μg∙L−1), trifluralin (0.17, 0.33, 0.66, 1.33, 2.65 mg∙L−1) and chlorothalonil (0.09, 0.18, 0.36, 0.72, 1.43 mg∙L−1) respectively. Main reproductive parameters including first pregnancy time, first brood time, the number of first brood and total fecundity after 21 d exposures at the same concentrations of pesticides as described above were also measured. The results showed that the activities of GST increased in lower concentrations and decreased in higher concentrations after 24 h exposure to three pesticides, respectively. The activities of SOD showed the same changes after 48 h exposure. With the time prolonged, the activities of GST decreased while the activities of SOD increased. After 21 d exposure, the first pregnancy time and first brood time were delayed, while the number of the first brood and total fecundity per female decreased with increasing concentrations. These results corroborated that GST activity was more sensitive to those pesticides than SOD activity, and there was a significant relationship between total fecundity and pesticides-dose(r&gt;0.94, n=6), GST activity after 48 h exposure and total fecundity after 21 d exposure (r&gt;0.92, n=6).

The spatial distribution of organochlorine pesticides and halogenated flame retardants in the surface sediments of an Arctic fjord: The influence of ocean currents vs. glacial runoff

Selected organochlorine pesticides (OCs) and halogenated flame retardants (HFRs) were analyzed in surficial fjord sediments collected down the length of Kongsfjorden, Svalbard in the Norwegian high Arctic. Hexachlorocyclohexane (α-HCHs) was found to be the most abundant OC in the sediment, followed by BDE-209>chlordane>α-endosulfan>Dechlorane Plus (anti-DP)>trifluralin concentration ranges were high over the relatively small study area of the fjord (e.g. ∑HCH: 7.2–100pgg−1 dry weight (dw)), with concentrations broadly similar to, or lower than, measurements conducted in other parts of the Arctic. Concentrations of legacy OCs, including both HCH isomers and chlordane showed a decreasing trend from the outer, seaward end of the fjord to the inner, glacier end of the fjord. Conversely, sediment concentrations of α- and β-endosulfan (0.1–12.5pgg−1 dw) increased from the outer fjord to the inner fjord. This contrasting pattern may be attributed to the influence of historical vs. contemporary sources of these chemicals to the fjord area, whereby the North Atlantic/West Spitzbergen oceanic current dominates the transport and input of the legacy OCs, whereas atmospheric deposition and meltwater runoff from the glaciers influence the inner fjord sediments for endosulfan. Interestingly, BDE-209 and Dechlorane Plus did not reveal any clear spatial trend. It is plausible that both glacial runoff and oceanic current end members are playing a role in introducing these chemicals to the fjord sediments. The relatively low fractional abundance of the syn-DP isomer (fsyn), however, indicates the long-range transport of this chemical to this Arctic site.

Evaluation of potential genotoxic effect of trifluralin inHelianthus annuusL. (sunflower)

In this study, the genotoxic effects of the herbicide trifluralin on the root meristem cells of sunflowers (Helianthus annuus L.) were investigated. The roots were treated with 5 10, 20 and 40 parts per thousand concentrations of trifluralin for 24, 36 and 48 h, with a control for each combination. The morphological changes occurring in sunflower roots with the different herbicide concentrations were monitored. The mitotic index and mitotic abnormalities were determined in both control and test groups. Mitotic index decreased with increasing herbicide concentration at each exposure time. The mitotic abnormalities were recorded as disturbed prophase, c-mitosis, stickiness, laggards and chromatid bridges. The micronucleus was observed at interphase and its frequency was calculated in different test solutions. Thus, the genotoxic potency of trifluralin with different tests was assessed by using root tip cells of Helianthus annuus.