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Gas chromatography-ion mobility spectrum (GC-IMS) is used to analyze and compare the differences in aroma among different tobacco samples. The aroma substances in tobacco samples in Jilin Changchun are the richest, while those in Guangdong Nanxiong are the lowest. The concentrations of aroma substances such as decanal, 1-hydroxy-2-propanone, and 2-methylbutanol were the highest in Guangdong Nanxiong of the three. The concentration of 1-hexanol, cyclohexanone, pentanoic acid, and other aroma substances in Fujian Nanping was high. The concentration of 2-acetylfuran, 2-octanol, isopentanol, 3-methylvaleric acid, phenylacetic acid, and other aroma substances in Changchun area of Jilin Province was low. Through principal component analysis and similarity research, both tobaccos can be distinguished by their production areas and grades from the same.

Root-knot nematode is an important soil pest in horticulture crops and constrains the protected cultivation development after methyl bromide (MB) was phased out in China. Dimethyl disulfide (DMDS) exhibits excellent efficacy against nematodes. Laboratory experiments and field trials were set up to clarify DMDS dose, efficacy, and yield. A dose-response experiment using three methods showed that DMDS presented high efficacy against the nematode Meloidogyne incongnita. The LC50 values of direct fumigation activity in the dessicator method were 0.086 and 0.070 mg L-1 for DMDS and 1,3-D, 29.865 and 18.851 mg L-1 for DMDS and 1,3-D of direct contact activity in the small tube method, 6.438 and 3.061 mg L-1 for DMDS and 1,3-D of soil fumigation activity in the soil fumigation method, respectively. The field trials indicated that DMDS showed an excellent efficacy of 80%-94% on root-knot nematode applied at 10-100 g m-2 on tomato in Tongzhou, Beijing. The crop yields showed no significant difference after applying 10-80 g m-2 DMDS. Results indicate that DMDS applied at 10 g m-2 for controlling root-knot nematode in Beijing is cost effective. In conclusion, DMDS is an excellent soil fumigant that can be used for controlling root-knot nematode and can be an potential novel alternative to MB in China.

BACKGROUND Ginger (Zingiber officinale Roscoe) is widely planted around the world. Owing to continuous planting, ginger is seriously affected by soilborne fungi, bacteria, and nematodes. Although preplant soil fumigation is an effective prevention strategy of soilborne diseases, individual fumigant and technology could not provide effective control of ginger soilborne disease. In our research, different combinations of soil fumigants and seed rhizome treatments were evaluated by monitoring the soil pathogens population, ginger growth, yield, and estimation of economic benefits. RESULTS: Soil fumigation effectively reduced the population of soilborne pathogens, and chloropicrin had a better control effect on soilborne pathogens than dazomet did. Preplant soil fumigation and seed rhizome treatment not only provide good control of soilborne disease, but also reduced the incidence of plant foliar pest and disease. Average yield increase rate of seed rhizome treatment was 12.0%; the highest yield increase was 24.4%. The average cost of seed rhizome treatment only increased by about 2.86%, but the rate of net revenue increase for the seed rhizome treatment reached up to 19.1%. CONCLUSION: Seed rhizome treatment is a very cost‐effective soilborne disease control technology. In the management of soilborne diseases, the combined application of soil fumigation and seed rhizome treatment can reduce the risk of crops infected by soilborne diseases and ensure high and stable crop yields. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

We report the synthesis and characterization of novel chromophores based on chlorogenic acid. The structure analysis and photophysical properties were studied to investigate the structure of the new chromophores. Such chromophores showed a great improvement in water solubility, which can explain application areas such as molecule probes, SHG imaging, and photodynamic/photothermal therapy. In addition, both chromophores A and B displayed good thermal stability with an onset decomposition temperature over 200 °C. These results showed that chromophores A and B had good thermal stability and nonlinear optical properties and are a promising candidate for practical use. [ABSTRACT FROM AUTHOR]

Biopesticides have proven to be suitable for the control of agricultural diseases and insects. Natural products and micro-organisms have been used as biopesticides worldwide as they can be sourced from the environment, they are generally safe to non-target organisms including humans, they have reduced persistence in the environment, and they are potentially acceptable for use in organic agriculture. Compared with synthetic pesticides, new biopesticides can gain regulatory approval faster. They can also be developed in less time and are much less expensive to develop. In China, some biopesticides currently being developed may be suitable alternatives to chemical pesticides such as Bacillus thuringiensis, Jinggangmycin, pyrethrins and brassinolide. This review summarizes the mode of action of biopesticides and describes their current development for use in agriculture. [ABSTRACT FROM AUTHOR]

The quantity of soil fumigants has increased globally that has focused attention on their environmental behavior. However, simultaneous analysis of traces of fumigant residues is often unreported because analysis methods are not readily available to measure them at low concentrations. In this study, typical solvent extraction methods were compared with headspace solid‐phase microextraction methods. Both methods can be used for simultaneously measuring the concentrations of five commonly used soil fumigants in soil or water. The solvent extraction method showed acceptable recovery (76–103%) and intraday relative standard deviations (0.8–11%) for the five soil fumigants. The headspace solid‐phase microextraction method also showed acceptable recovery (72–104%) and precision rates (1.3–17%) for the five soil fumigants. The solvent extraction method was more precise and more suitable for analyzing relatively high fumigant residue levels (0.05–5 μg/g) contained in multiple soil samples. The headspace solid‐phase microextraction method, however, had a much lower limits of detection (0.09–2.52 μg/kg or μg/L) than the solvent extraction method (5.8–29.2 μg/kg), making headspace solid‐phase microextraction most suitable for trace analysis of these fumigants. The results confirmed that the headspace solid‐phase microextraction method was more convenient and sensitive for the determination of fumigants to real soil samples. [ABSTRACT FROM AUTHOR]

Abstract: Many crops are produced using soil fumigation and chemical pesticides to control soil-borne fungi and bacterial diseases, nematodes and weeds. Fumigation of soil, however, may alter its ability to adsorb, degrade and volatilize pesticides, which can then change the potential for pesticides to leach into groundwater. Soil adsorption kinetics, Freundlich isothermal adsorption and pesticide degradation techniques were used to determine the potential for pesticides to pollute groundwater in fumigated soil. The effect on soil pesticide adsorption in different types of chloropicrin (CP) fumigated soils was also examined. We observed that the equilibrium adsorption (q e) decreased significantly at 24 h. Soil fumigation decreased the Freundlich K f and K foc values, and increased the Freundlich exponent 1/ n values, for pesticides in fumigated Beijing soil. Soil fumigation influenced the K f of pendimethalin, oxyfluorfen and abamectin the most, which themselves had a larger K f in untreated soil. This indicated that the greater the soil pesticide adsorption the greater the influence of a fumigation treatment on that pesticide. The K f was decreased more in the Heilongjiang and Beijing CP-fumigated soils that had high organic carbon content compared to Hunan soil. Fumigation of the soil with CP extended the half-life values of fosthiazate (from 34.3 to 43.1 days) and azoxystrobin (from 52.9 to 64.2 days), which increased their potential to leach into groundwater. Famers should minimize the quantity of some pesticides applied to fumigated soil, or apply some pesticides 60 days after fumigation, in order to avoid ground water pollution when crops are grown in fields or greenhouses. Graphical abstract Image 1 Highlights • Soil fumigation decreased the K f and Koc values of pesticides in Beijing soil. • K f was decreased more in higher organic carbon content soil when fumigated with CP. • CP-fumigated soil extended the degradation half-life of fosthiazate and azoxystrobin. • The potential for pesticides to leach into groundwater increased in CP-fumigated soil. Soil fumigation decreased the Freundlich K f and K foc values of pesticides and increased their potential to leach into groundwater. [ABSTRACT FROM AUTHOR]

Dimethyl disulfide (DMDS) is a potential alternative to methyl bromide for soil fumigation to control soil‐borne disease. Laboratory experiments were conducted to investigate the effects of combinations of soil and environmental factors of DMDS degradation in soil. The results showed that soil pH and soil organic matter content are the major factors influencing the degradation of DMDS in soil. Generally, DMDS degradation was significantly slower in acidic and high organic content soils. The degradation rate increased with temperature and water content. However, when the temperature exceeded 35°C, the degradation rate decreased, and when the soil water content was raised to 10%, the change in DMDS degradation was not significant in Fangshan soil. The degradation of DMDS in soil depended on the initial application rate. Degradation slowed down as the fumigant application rate increased. DMDS degradation in soil was restrained by the addition of organic matter to soil, and the effect was enhanced by increased dosage. DMDS degradation in soil was also restrained by the use of chemical fertilizers except when amended with sodium dihydrogen phosphate and sodium thiosulfate. The impact of fumigant application rates and chemical fertilizers on bacterial communities in soil was determined by 16S rRNA amplicon sequencing. The results showed that bacterial diversity was affected by different treatments. Our study provides useful information to evaluate environmental safety assessments of DMDS in soil. [ABSTRACT FROM AUTHOR]

The influence of soil fumigation on microorganisms involved in transforming nitrogen remains little understood, despite the use of fumigants for many decades to control soil-borne pathogens and plant-parasitic nematodes. We used real-time PCR (quantitative polymerase chain reaction) and 16S rRNA gene amplicon sequencing techniques to monitor changes in the diversity and community structure of microorganisms associated with nitrogen transfer after the soil was fumigated with dazomet (DZ). We also examined nitrous oxide (N2O) emissions from these microorganisms present in fumigated fluvo-aquic soil and lateritic red soil. Fumigation with DZ significantly reduced the abundance of 16S rRNA and nitrogen cycling functional genes (nifH , AOA amoA , AOB amoA, nxrB, narG, napA, nirK, nirS, cnorB, qnorB , and nosZ). At the same time, N2O production rates increased between 9.9 and 30 times after fumigation. N2O emissions were significantly correlated with NH 4 + , dissolved amino acids and microbial biomass nitrogen, but uncorrelated with functional gene abundance. Diversity indices showed that DZ temporarily stimulated bacterial diversity as well as caused a significant change in bacterial community composition. For example, DZ significantly decreased populations of N2-fixing bacteria Mesorhizobium and Paenibacillus , nitrifiers Nitrosomonas , and the denitrifiers Bacillus, Pseudomonas , and Paracoccus. The soil microbial community had the ability to recover to similar population levels recorded in unfumigated soils when the inhibitory effects of DZ fumigation were no longer evident. The microbial recovery rate, however, depended on the physicochemical properties of the soil. These results provided useful information for environmental safety assessments of DZ in China, for improving our understanding of the N-cycling pathways in fumigated soils, and for determining the potential responses of different N-cycling groups after fumigation. [ABSTRACT FROM AUTHOR]

Background: Root-knot nematode (Meloidogyne spp., RKN) causes a disease that significantly reduces the yield of greenhouse cucumber crops year after year. Chemical control based on a single pesticide is now unreliable mainly due to pest resistance. Fumigant and non-fumigant pesticide combinations can potentially result in effective and economic RKN control. Results: Combining the insecticide abamectin (ABM) with fumigants dazomet (DZ) or chloropicrin (CP) significantly extended the half-life of ABM by an average of about 1.68 and 1.56 times respectively in laboratory trials, and by an average of about 2.02 and 1.69 times respectively in greenhouse trials. Laboratory experiments indicated that all the low rate ABM combination treatments controlled RKN through a synergistic effect. ABM diffused into the nematode epidermis more rapidly when ABM was combined with DZ and CP, giving effective nematode control and an increase cucumber total yield, compared to the use of these products alone. ABM combined with CP or DZ produced significantly higher total cucumber yield than when these products were used alone. Conclusions: A low concentration of ABM combined with DZ in preference to CP would be an economic and practical way to control nematode and soilborne fungi in a greenhouse producing cucumbers. [ABSTRACT FROM AUTHOR]

In order to explore the application of organic conjugated small molecules in bioimaging, a novel functional chromophore with A-π-D-π-A structure (Cr-3) was synthesized through Knoevenagel condensation reaction, consisting of carbazole unit as electron donor and cyanoacetic acid as electron acceptor groups. To improve the water solubility of this conjugated molecule, three carboxyl groups were introduced to chromophoreCr-3. Compared to the traditional D-π-A chromophores, chromophoreCr-3showed the great improvement in water with the solubility of 2000 ppm. Also, the thermal stability of chromophoreCr-3was also studied. The thermal decomposition temperature (Td) ofCr-3was approximately 180°C, which was attributed to the dehydration of the carboxyl groups. Though the second harmonic generation (SHG) effect was not very high, it is large enough for the detection of SHG signal in water solution (0.28 pm/V). [ABSTRACT FROM AUTHOR]

BACKGROUND Dimethyl disulphide (DMDS) is a new and effective alternative to methyl bromide for soil fumigation. The effect of biochar on the fate of DMDS in soil is not fully understood. The objective of this study was to determine the degradation kinetics of DMDS in different soils and evaluate the effect of biochar amendment on DMDS degradation using incubation experiments. RESULTS The degradation half-life of DMDS was between 1.05 and 6.66 days under non-sterile conditions, and 12.63 to 22.67 days under sterile conditions in five types of soil. Seven out of the eight tested biochar amendments (BC-2 to BC-8) delayed the degradation of DMDS in soil, increasing the half-life of DMDS in Fangshan soil from 1.05 to 1.16-5.87 days following amendment with 1% (w/w) biochar. The degradation rate of DMDS in Fangshan soil accelerated as the amendment rate of BC-1 increased, and decreased as the amendment rate of BC-7 increased. CONCLUSION Biodegradation is an important degradation route for DMDS in soil, and DMDS degraded faster in alkaline soil. The effects of biochar amendments on DMDS degradation in soil are determined by complex multiple factors (such as surface area, pH and physicochemical composition), rather than by any single property of biochar. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The antifungal activity of oils extracted from Eupatorium adenophorum was tested against five phytopathogens in vitro . Oil extracts inhibited the mycelial growth of Phytophthora capsici which causes phytophthora blight in pepper. The minimum inhibitory concentration of oils against P. capsici was 500 μg/ml after 7 days incubation. At the ultrastructural level, oil extracts caused complete disorganization of intracellular organelles, cytoplasm depletion, disruption of cytoplasmic membranes and the cell wall. Membrane permeability increased with the increasing concentration of oil extracts. These results suggested that these oil extracts exhibited multiple modes of action including disruption of the cell membrane system. Furthermore, oil extracts combined with synthetic fungicides synergistically inhibited mycelial growth of P. capsici , which creates the possibility of reducing fungicide concentration needed to successfully control phytophthora blight in commercial pepper production. This study's use of multiple methods of analysis has increased our understanding of the mode of action of E. adenophorum oil extracts against P. capsici . [ABSTRACT FROM AUTHOR]

Oils extracted from the leaves of Eupatorium adenophorum were tested in vitro and in vivo against the soilborne pathogen Pythium myriotylum which causes soft rot, a devastating disease of commercial ginger production in China. Twelve compounds accounting for 99.15% of the total oil composition were identified by GC-MS. The major components were 10Hβ-9-oxo-agerophorone (37.03%), 10Hα-9-oxo-agerophorone (37.73%) and 9-oxo-10, 11-dehydro-agerophorone (23.41%). Antifungal activity was tested by the poisoned food technique against P. myriotylum, indicating minimum inhibitory concentrations of 100μg/ml after 7 days incubation. In addition, the oil extracts greatly inhibited the formation of both wet and dry mycelial biomass. The combination of E. adenophorum oil extracts and synthetic fungicides showed a strong synergistic effect, inhibiting the mycelial growth in in vitro assays. The synergistic effect of oil extracts with fungicides could allow fungicides to be used at reduced rates in the future which has environmental advantages. Oil extracts applied at 160 and 200μg/ml concentrations to ginger rhizomes before inoculation with P. myriotylum significantly reduced the infection rate in ginger. Examination by light and transmission electron microscopy revealed that oil extracts caused swelling of the hyphae, disruption of the cell wall, degradation of the cytoplasmic organelles and shortening of the cytoplasmic inclusion. These results suggested that the plasma membrane and endomembrane systems of P. myriotylum were severely damaged by the oil extracts of E. adenophorum which offer significant potential for use as a fungicide to control P. myriotylum. [ABSTRACT FROM AUTHOR]

In this work, we report the synthesis of mesoporous carbon derived from nonporous MOFs without any heteroatom doping or residual metal, which is highly efficient for the electrocatalytic oxygen reduction reaction. The excellent ORR activity is attributed to both high specific surface area and mesoporous structure. [ABSTRACT FROM AUTHOR]

Flame soil disinfestation (FSD) is a novel, promising non-chemical method to control soilborne nematodes, fungal and bacterial pathogens in China. The efficacy of FSD on soilborne nematodes, fungal and bacterial pathogens was evaluated during two field trials. The field trials revealed that the treatment with FSD once (FSD1) and treatment with FSD twice (FSD2) sharply reduced the total number of soilborne nematodes (>95%) and completely controlled Meloidogyne incognita in the soil. Both FSD1 and FSD2 also provided promising efficacy against soilborne Fusarium oxysporum (>44%), Phytophthora spp. (>47%) and Ralstonia solanacearum (>67%) on media. However, there was no significant difference between FSD1 and FSD2 in controlling soilborne nematodes, fungal and bacterial pathogens ( P = 0.05). Currently, there are two challenges to distribute the technology in China: its high cost and relatively low efficiency because of the low speed of application compared with soil chemical fumigation. Despite the drawbacks, FSD is still promising in organic agriculture for controlling soilborne nematodes, fungal and bacterial pathogens. [ABSTRACT FROM AUTHOR]

In order to explore the application of organic conjugated small molecules in bio-imaging, novel functional chromophore with A-π-D-π-A structures (chromophore OY-2) was designed and synthesized. To improve the water solubility of this conjugated molecule, two carboxyl groups were introduced to chromophore OY-2 in the electron acceptor parts. Compared to the traditional D-π-A chromophores, chromophore OY-2 showed us great improvement in water solubility. The solubility of chromophore OY-2 in water could reach 300 ppm. Else, the thermal stability of chromophore OY-2 was also studied. Due to the presence of multi-carboxyl groups, the thermal stability of chromophore OY-2 was not very good. The initial decomposition temperature was just above 210 °C, which was attributed to the dehydration of the carboxyl groups. Though the SHG effect was not very high, it is large enough for the detection of SHG signal in water solution (0.2-0.3 pm/V). [ABSTRACT FROM AUTHOR]

In this communication, we, for the first time, prepared phosphorus-doped cobalt disulfide nanosheets as highly advanced electrocatalysts for the hydrogen evolution reaction. It was demonstrated that P doping could significantly enhance the electrocatalytic performance of CoS2 nanosheets in terms of onset overpotential, Tafel slope, exchange current density, and stability. [ABSTRACT FROM AUTHOR]

Biochar has sorption capacity, and can be used to enhance the sequestration of volatile organic contaminants such as pesticides in soil. Chloropicrin (CP) is an important soil fumigant for the production of many fruit and vegetable crops, but its emissions must be minimized to reduce exposure risks and air pollution. The objective of this study was to determine the capacity of biochar to adsorb CP and the effect of biochar amendments to soil on CP emission, concentration in the soil gas phase, degradation in soil and CP bioactivity for controlling soil borne pests. CP emission and concentration in the soil air phase were measured from packed soil columns after fumigant injection at 20-cm depth and application of selected doses of biocharto the surface 5 cm soil. Laboratory incubation and fumigation experiments were conducted to determine the capacity of biochar to adsorb CP, the effects on CP degradation and, separately, CP’s bioactivity on soil borne pests in soil amended with biochar. Biochar amendment at 2% to 5% (w/w) greatly reduced total CP emission losses by 85.7% - 97.7% compared to fumigation without biochar. CP concentrations in the soil gas-phase, especially in the top 5 cm of soil, were reduced within 48 h following application. The half-life of CP decreased from 13.6 h to 6.4 h as the biochar rate increased from 0% to 5%. CP and its metabolite (dichloronitromethane) both degraded more rapidly in pure biochar than in soil. The biochar used in the present study had a maximum adsorption capacity for CP of less than 5 mg g-1. There were no negative effects on pathogen and nematode control when the biochar used in this study was less than 1% (on a weight basis) in soil. Biochar amendment to soil reduced the emissions of CP. CP concentrations in the top 5 cm of soil gas-phase were reduced. CP degradation was accelerated with the addition of biochar. The biochar used in the present study had a low adsorption capacity for CP. There were no negative effects on pathogen and nematode control when the biochar amendment rate was less than 1% (by weight). The findings would be useful for establishing guidelines for biochar use in soil fumigation. [ABSTRACT FROM AUTHOR]

Methyl bromide (MB) and other alternatives were evaluated for suppression of Fusarium spp., Phytophthora spp., and Meloidogyne spp. and their influence on soil microbial communities. Both Fusarium spp. and Phytophthora spp. were significantly reduced by the MB (30.74 mg kg-1), methyl iodide (MI: 45.58 mg kg-1), metham sodium (MS: 53.92 mg kg-1) treatments. MS exhibited comparable effectiveness to MB in controlling Meloidogyne spp. and total nematodes, followed by MI at the tested rate. By contrast, sulfuryl fluoride (SF: 33.04 mg kg-1) and chloroform (CF: 23.68 mg kg-1) showed low efficacy in controlling Fusarium spp., Phytophthora spp., and Meloidogyne spp. MB, MI and MS significantly lowered the abundance of different microbial populations and microbial biomass in soil, whereas SF and CF had limited influence on them compared with the control. Diversity indices in Biolog studies decreased in response to fumigation, but no significant difference was found among treatments in PLFA studies. Principal component and cluster analyses of Biolog and PLFA data sets revealed that MB and MI treatments greatly influenced the soil microbial community functional and structural diversity compared with SF treatment. These results suggest that fumigants with high effectiveness in suppressing soil-borne disease could significantly influence soil microbial community. [ABSTRACT FROM AUTHOR]

In this work, for the first time, we have developed a one-step hydrothermal method to synthesize a hybrid material consisting of NiCo2S4 nanocrystals grown on reduced graphene oxide as an efficient nonprecious electrocatalyst for the oxygen reduction reaction (ORR) in alkaline medium. Our synthetic process here is quite simple, straightforward and environmentally benign. NiCo2S4–rGO shows significantly enhanced catalytic activity over rGO and NiCo2O4–rGO, and close reduction activity but much superior methanol tolerance and better durability than the commercial Pt/C catalyst. The half wave potential (E1/2) for the NiCo2S4–rGO hybrid is only about 62 mV more negative than that of the commercial Pt/C catalyst but 81 mV more positive than that of NiCo2O4–rGO, 116 mV than that of rGO. The superior performance of NiCo2S4–rGO is presumably attributed to a combination effect of mixed valence in transition metal composites favorable for O2 to be absorbed/reduced and a synergetic effect resulting from NiCo2S4 and rGO. The advantages over NiCo2O4–rGO might be ascribed to the inverse spinel crystal structure of NiCo2S4, its relative higher conductivity, and the fact that Na2S serves both as the S source and reducing agent facilitating an increase in the hybrid catalytic activity. [ABSTRACT FROM AUTHOR]

BACKGROUND Two soil fumigants, chloropicrin ( CP) and dimethyl disulfide ( DMDS), were used to control Fusarium wilt disease ( FWD) which caused large economic losses in strawberries. The fumigants were evaluated alone and in combination in a laboratory study and in strawberry greenhouses. RESULTS Laboratory tests found that combinations of CP and DMDS indicated a positive synergistic activity on Fusarium oxysporum. A newly developed quantitative assay for F. oxysporum involving real-time PCR was used successfully to evaluate F. oxysporum control by the fumigants; it provided similar results to the selective medium but was less time-consuming and less labor intensive. Greenhouse trials revealed that the combination of CP and DMDS successfully suppressed the incidence of FWD and sharply reduced the population density of F. oxysporum, which significantly increased fruit branch number and maintained a good strawberry yield, higher than methyl bromide ( MB) treatment. All of the treatments provided significantly better results than the non-treated control. CONCLUSION This study confirms that the newly developed real-time PCR quantitative assay for F. oxysporum was suitable for the control efficacy evaluation of soil fumigants and that the novel fumigant combination of CP and DMDS offers a promising effective alternative to MB for the control of F. oxysporum in strawberry greenhouses. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]