Development of novel rapid-growing and delicious Pleurotus djamor strains through hybridization.

The development of fast-growing/short cropping period oyster mushroom (Pleurotus species) having good taste is one of the important needs of mushroom growers. Pleurotus djamor strain woody1, collected recently from the dead wood, has a short cropping period of 30 days but a moderately acceptable taste. One of the cultivated Pleurotus spp., P. djamor strain MDU1, has good taste but a long cropping period of 47 days. Thus, genetic improvement of P. djamor was carried out between these two strains by pairing monokaryons (anastomosis) to develop elite hybrid strains having a short cropping period and good taste. Monokaryons of parental strains showed variation in time required for germination; i.e., basidiospores of P. djamor strain woody1 germinated and developed monokaryotic colonies in 6 days, whereas that of P. djamor strain MDU1 developed monokaryotic colonies in 8 days of incubation. In addition, variation in the growth rate and morphology of the monokaryotic mycelia of both parental strains was noticed, and fast-growing monokaryons were selected for anastomosis. Out of 60 crosses made between mycelia of monokaryotic isolates of both parental strains, 20 crosses showed clamp connection, indicating that they were successful crosses. Out of 20 hybrids, two hybrid strains, viz., W2M4 and W4M4, exhibited higher yields than their parents. They exhibited the short cropping period trait, good taste attribute, and some specific volatile metabolites. This study showed that the developed two hybrid varieties, having desirable agronomic traits, could be used in mushroom farming to increase the mushroom grower's income.

Determination of 73 multi-class pesticides in okra (Abelmoschus esculentus L.) fruits using LC-MS/MS and GC-MS/MS and estimation of analytical uncertainty of measurement.

This study developed a method to simultaneously determine 73 multi-class pesticides in okra fruit using LC-MS/MS and GC-MS/MS. The sample was extracted with acetonitrile and subsequent clean-up through dispersive-SPE method. The quantification level of the technique was 0.01 µg g-1 and compliance to the MRLs fixed by the regulatory bodies like EU and FSSAI. The recovery at 10, 50, and 100 µg kg-1 spiked levels; intra and inter-day precision at 50 µg kg-1 were found within 70-120% with RSD less than 15% with LC-MS/MS and GC-MS/MS. Measurement uncertainty was in the range of 1.81 to 12.91 µg kg-1 estimated at 50 µg kg-1. The matrix effects were slightly higher for LC than GC-compatible pesticides. Risk assessment for pesticides detected in the field and market samples found no hazardous to the consumers except profenofos. The proposed method is highly sensitive, reproducible for the complex matrix like okra, and meets the regulatory standards.

Determination of Synthetic Pyrethroids and Hexaconazole Residues in curry leaves and decontamination through household techniques.

A multiresidue method was developed and validated for the simultaneous determination of eight synthetic pyrethroids and hexaconazole fungicide residues in curry leaves. The method involves extraction of leaf sample with ethyl acetate, purified by dispersive SPE with primary secondary amine and graphitized carbon black. The gas chromatography-electron capture detector (GC-ECD) used for residue estimation and confirmed using gas chromatography-mass spectrometry (GC-MS) with the LOQ of 0.03 µg/g. The recoveries of all pesticides were in the range of 75 to 110% with a relative standard deviation of less than 7%. The matrix effect was within the acceptable limit of less than 20% as prescribed by SANTE guidelines. The decontamination was carried out to reduce the concentration of residues in curry leaves by different household techniques and lemon juice (2%) solution was found to be more effective (35.71-56.52%) followed by 2% tamarind (23.48 to 42.94%), hot water (18.44 to 46.74%), 2% salt water (10.98 to 42.71%) and least in tap water (3.57 to 27.84%). The method was successfully applied for routine monitoring of pesticide residues in curry leaves.

Production, stability and degradation of Trichoderma gliotoxin in growth medium, irrigation water and agricultural soil.

Gliotoxin produced by Trichoderma virens is inhibitory against various phytopathogenic fungi and bacteria. However, its stability in soil-ecosystem has not yet been well-defined. This study aimed to decipher its persistence and behaviour in growth media, irrigation water and soil ecosystems. Gliotoxin production was noticed at logarithmic growth phase and converted into bis-thiomethyl gliotoxin at late stationary growth phase of T. virens in acidic growth medium. But, no gliotoxin production was observed in neutral and alkaline growth medium. Gliotoxin was stable for several days in acidic water but degraded in alkaline water. Degradation of gliotoxin was more in unsterile soil than sterile soil and also that was higher under wet soil than dry soil. Degradation of gliotoxin was hastened by alkaline pH in wet soil but not in dry soil. Under unsterile soil conditions, high soil moisture increased the degradation of gliotoxin and the degradation of gliotoxin occurred quickly in alkaline soil (in 5 days) compared to acidic soil (in 10 days). Under sterile soil conditions, high soil moisture also enhanced the degradation of gliotoxin but level of degradation was less compared to unsterile conditions. Thus, gliotoxin stability is influenced mainly by the soil wetness, soil microbial community and pH conditions.

Dissipation kinetics, dietary and ecological risk assessment of chlorantraniliprole residue in/on tomato and soil using GC-MS.

An alternate single quadrupole gas chromatography coupled with electron ionization mass spectrometry (GC-EI-MS) method was developed and validated for the determination chlorantraniliprole residue in tomato and soil. The target analyte was extracted from selected matrices with acetonitrile followed by dispersive solid-phase extraction clean up with primary secondary amine and graphitized carbon black sorbent to remove co-extractives prior to analysis. Limit of quantification of the method was 0.01 µg/g and the recovery of chlorantraniliprole was in the range of 92-99% with RSD of less than 3%. The dissipation kinetics of chlorantraniliprole in tomato and soil followed first-order kinetics with the half-life of 1.26 and 1.77 days, respectively. A safe waiting period of 1 day suggested for safe consumption of tomato fruits considering the FSSAI maximum residue limit of 0.6 µg/g. The residue concentrations were reduced in the range of 13 to 64% from tomato fruit using simple household approaches. The present study suggested that the use of chlorantraniliprole in tomato does not seem to pose any dietary risk to consumers. The ecological risk quotient (RQ) values indicated that the chlorantraniliprole residues in the soil may pose a medium level of risk to earthworms and arthropods during this period.

Simultaneous determination of 79 pesticides in pigeonpea grains using GC-MS/MS and LC-MS/MS.

Pigeonpea grains are important sources of vegetarian proteins. It is the paramount importance to check the pesticide residues due to their frequent use during production. The LC-MS/MS and GC-MS/MS analytical method was developed and validated for the simultaneous determination of 79 pesticide residues in pigeonpea. The LOD and LOQ of the analytical method were in the range of 0.53 to 3.97 and 1.60 to 10.05 µg kg-1, respectively, with a correlation coefficient of more than 0.997. Average recoveries were in the range of 80 to 118.8%, with the RSD of less than 15%. Measurement uncertainty (Ux) for pesticides was in the range of 3.42 to 12.76 µg kg-1 evaluated at 50 µg kg-1. The method was applied to analyze the sample collected from the farmer's field. This method could be useful for routine analysis of selected pesticide residue for monitoring purposes.

Dissipation Kinetics and Environmental Risk Assessment of Thiamethoxam in the Sandy Clay Loam Soil of Tropical Sugarcane Crop Ecosystem.

Thiamethoxam 75 SG has recently got registered for use against shoot borer and termites of sugarcane. It is the only neonicotinoid having label claim against both the major pests of sugarcane. The dissipation kinetics and environmental risk assessment of thiamethoxam 75 SG were studied in a typical tropical sugarcane crop ecosystem as detailed reports are lacking. Rapid and sensitive method adopted to determine the residues of thiamethoxam in the soil employing HPLC could provide more than 95.5% recoveries. The insecticide was observed to persist in the sandy clay loam soil for 60 days and reached below the detectable level of less than 0.01 mg/kg (LOQ = 0.01 mg/kg) on 75th day when applied @ 120 g a.i./ha. The half-life was worked out to be 16.50 days. At double the recommended dose (240 g a.i./ha), the insecticide persisted up to 75 days with the half-life of 16.91 days. The risk quotient values indicated medium to low level of risk to earthworms during the course of degradation of thiamethoxam in the soil.

Persistence, dietary and ecological risk assessment of indoxacarb residue in/on tomato and soil using GC-MS.

An efficient single quadrupole gas chromatography with mass spectrometry method was developed and validated for the determination of indoxacarb residues in tomato and soil. Residues were extracted from the samples using acetonitrile as extracting solvent and the extracts were purified through primary secondary amine and graphitized carbon black. Recoveries were obtained in the range of 92.12-110.51% with the relative standard deviation of 1.32-4.32%. Indoxacarb dissipated with half-life of 3.12-3.21 and 1.24-1.35d for tomato and soil, respectively following doses of indoxacarb 14.5% SC at 60, 90 and 120 g.a.i./ha. Safe waiting periods were found to be 1-3d. The residues were removed from tomato fruit was in the range of 16.73 to 54.32% using simple decontamination approaches. The present study suggest that the use of indoxacarb in tomato at recommended dose, does not seem to pose any dietary risk to the consumers. The soil RQ values indicated low level of risk to earthworms and arthropods.

Simultaneous determination of organophosphorus residues on curry leaf, decontamination through household techniques and risk assessment.

A simple analytical method was developed and validated, as per SANTE 2017 guidelines, for simultaneous determination of 10 organophosphorus residues in curry leaf using gas chromatography with flame photometric detection, and confirmed using gas chromatography-mass spectrometry. Samples were extracted with ethyl acetate and cleaned up with primary secondary amine and graphitized carbon black. Average recoveries were in the range 80-108% with the RSD of less than 8%. The effects of different household cleaning techniques to reduce the concentration of pesticide residues in curry leaf were evaluated and found to remove 2-65% of residues. The method was applied to analyse sample to fresh curry leaf samples, and analysis of potential health risks estimated the residues did not pose a direct hazard. This method could be useful for routine analysis of organophosphorus residue for monitoring purposes.

Dissipation kinetics of beta-cyfluthrin and imidacloprid in tea and their transfer from processed tea to infusion.

Dissipation kinetics of mixed formulation consisting beta-cyfluthrin and imidacloprid in tea crop under an open field ecosystem was investigated. The mixed formulation was applied on tea plant at recommended (27 + 63) and double the recommended (54 + 126g a.i./ha) dose and residues were determined using gas chromatography-electron capture detector and high performance liquid chromatography-photodiode array detector for beta-cyfluthrin and imidacloprid, respectively. The limit of quantification of analytical method was 0.05µg/g and the average recoveries were ranged from 88.36% to 103.49% with relative standard deviations of less than 6% at three spiked levels. The experimental results showed that in the green tea leaves imidacloprid dissipated faster than beta-cyfluthrin with the half-life ranging between 1.20-1.39 and 2.89-3.15days, respectively. The beta-cyfluthrin residues present in the processed tea not transferred into the tea infusion during the infusion process and imidacloprid transferred in the range 43.12-49.7%. On the basis of the transfer of residues from processed tea to infusion, a waiting period of 17 days for tea plucking after pesticide application at recommended dose may be suggested.

Development, validation and application of a sensitive analytical method for residue determination and dissipation of imidacloprid in sugarcane under tropical field condition.

A simple and sensitive analytical method has been developed and validated for the determination of trace amounts of imidacloprid in/on sugarcane sett, stalk and leaf. The method optimized in the present study requires less volume of organic solvent and time. Hence, this method is suitable for high-throughput analyses involving large number of samples. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.003 and 0.01 mg/kg, respectively. The recovery and relative standard deviation were more than 93 % and less than 4 %, respectively. Thus, it is obvious that the analytical method standardized in this study is more precise and accurate enough to determine the residues of imidacloprid in sugarcane sett, stalk and leaf. The dissipation and translocation of imidacloprid residues from treated cane setts to leaf and stalk were studied by adopting this method. In sugarcane setts, the residues of imidacloprid persisted up to 120 days with half-life of 15.4 days at its recommended dose (70 g a.i./ha). The residues of imidacloprid were found to be translocated from setts to stalk and leaf. The imidacloprid residues were detected up to 105 days in both leaf and stalk. Dipping of sugarcane setts in imidacloprid at its recommended dose may result in better protection of cane setts and established crop because of higher initial deposit (>100 mg/kg) and longer persistence (>120 days).

Persistence and dissipation kinetics of chlorantraniliprole 0.4G in the soil of tropical sugarcane ecosystem.

Chlorantraniliprole 0.4 % GR has been in use for managing early shoot borer and top borer of sugarcane. Persistence and dissipation kinetics of granular formulation of chlorantraniliprole were studied in the soil of tropical sugarcane ecosystem by employing simple and sensitive analytical method. Limit of quantification of the method was 0.01 mg/kg and the recovery of chlorantraniliprole was in the range of 92.3-99.7 % with RSD of 1.14-3.0 %. The initial deposit of chlorantraniliprole in the soil was 0.513 and 1.031 mg/kg for the recommended (75 g a.i./ha) and double the recommended (150 g a.i./ha) doses, respectively. The residues were quantified up to 30 days after treatment irrespective of the doses applied. Half-life (t 1/2) was 6.60 and 6.73 days, respectively, for recommended and double the recommended doses of chlorantraniliprole.

Degradation pattern and risk assessment of carbendazim and mancozeb in mango fruits.

A supervised field trial was conducted at four different agroclimatic locations in India to evaluate the dissipation pattern and risk assessment of carbendazim and mancozeb in mango fruits following foliar application of mixed formulation of carbendazim 12% and mancozeb 63% fungicide (SAAF-75WP) at recommended dose (90 + 472.5) and double the recommended dose (180 + 945 g a.i. ha(-1)). Average initial deposition of carbendazim was in the range of 1.12 to 2.7 and 1.95 to 4.09 mg kg(-1) and for mancozeb in the range of 2.25 to 2.71 and 4.17 to 5.96 mg kg(-1), given at respective doses. Residues of carbendazim and mancozeb were dissipated to the below detectable limit 7 days after spray at recommended dosage in all the locations. The fungicide degradation followed a first order kinetics with half-lives of 1-5 and 1-3 days, for carbendazim and mancozeb, respectively. The TMRC values, calculated from residue data generated from all four locations, were found to be below the MPI in mango fruit, and hence, the fungicide will not cause any adverse effect after consumption of mango fruits. This data could provide guidance for the proper and safe use of this fungicide mixture for managing disease incidence in mango in India.

Persistence behaviour of deltamethrin on tea and its transfer from processed tea to infusion.

The dynamics and residues of deltamethrin in a tea grown in an open field ecosystem were investigated. The quantification was performed using gas chromatography-electron capture detection (GC-ECD) and confirmed by gas chromatograph-mass spectrometry (GC-MS) in selective ion monitoring (SIM) mode. The method was validated using blank samples spiked at three levels and the results showed that recoveries ranged from 87% to 101% with relative standard deviations (RSD) ranging of 0.7-7.1%. The residues of deltamethrin were found to dissipate following first order kinetics with half-life ranging between 3.04 and 3.54d for two different rates of foliar application. The deltamethrin residues are present in the processed tea are not transferred into the tea infusion during the infusion process, since their water solubility is extremely low. These results can be utilized in formulating the spray schedule and safety evaluation on deltamethrin tea crop.

Persistence and dissipation of flubendiamide and its risk assessment on gherkin (Cucumis sativus L.).

A supervised open field trial was conducted to evaluate the dissipation pattern and risk assessment of flubendiamide in gherkin fruits following foliar application of Fame 480 SC at 60 and 120 g a.i. ha(-1). Samples of gherkin fruits were drawn at different time intervals and quantified by HPLC-DAD. The maximum initial deposits of flubendiamide on gherkin were found to be 0.79 and 1.52 mg kg(-1), respectively, at recommended and double the recommended doses. The dissipation pattern of flubendiamide followed a first-order kinetics with half-lives of 1.87 to 2.16 days at 60 and 120 g a.i. ha(-1), respectively. The limit of quantification of flubendiamide and desiodo flubendiamide was observed to be 0.01 mg kg(-1) for gherkin fruit and soil substrates. Theoretical maximum residue contribution (TMRC) for flubendiamide was calculated and found to be well below the maximum permissible intake (MPI) on gherkin fruits. Thus, the application of flubendiamide at the recommended dose on gherkin fruits presents no human health risks and safe to consumers.

Dynamics and residues of mixed formulation of fenamidone and mancozeb in gherkin field ecosystem.

The dynamics and residues of mixed formulation of fenamidone and mancozeb in a gherkin field ecosystem were investigated. The quantification was performed using gas chromatography-electron capture detection (GC-ECD) and UV-vis spectrophotometry for fenamidone and mancozeb residues, respectively. The method was validated using blank samples spiked at three levels and the results showed that recoveries ranged from 92 to 98 and 90 to 96 percent with relative standard deviations (RSD) ranging of 0.78-5.9 and 2.04-4.41 percent for fenamidone and mancozeb, respectively. The compound degradation followed a first order kinetics with half-lives of 2.8-2.82 and 2.02-2.26 days, for fenamidone and mancozeb, respectively. Pesticide residues in fruit were below the EU maximum residue level (MRL) after 10 days for fenamidone (0.02 µg/g) and just after treatment for mancozeb (2 µg/g). These results can be utilized in formulating the spray schedule and safety evaluation for these pesticides in gherkin.

Dissipation of flubendiamide residues in/on cabbage (Brassica oleracea L.).

Residues of fubendiamide and its metabolite desiodo flubendiamide were estimated in cabbage and soil using high-performance liquid chromatography with UV-vis detector. The initial deposits of flubendiamide residues on cabbage were found to be 0.16 and 0.31 µg g(-1) following two applications of flubendiamide 20 WG at 12.5 (standard dose) and 25 (double dose) g a.i. ha(-1) respectively at 10-days interval. The half-life values (t(1/2)) of flubendiamide on cabbage ranged from 3.4 to 3.6 days. When flubendiamide applied at both the standard and double dose, no detectable residues were found in cabbage and soil at harvest. Thus, a waiting period of 1.63 days was suggested for the safe consumption of flubendiamide-treated cabbage. These data could provide guidance for the proper and safe use of this pesticide on cabbage crops in India.

Persistence behaviour of thiacloprid residues in/on green tea leaves, processed tea and tea infusion.

Thiacloprid residues were estimated in green tea leaves, processed tea and tea infusion by HPLC-Diode Array detection. The average initial deposits of thiacloprid (Alanto 240 SC) on the green tea leaves were found to be 3.72 and 6.77 µg g(-1) at single and double doses, respectively. The results showed that thiacloprid dissipated faster in green tea leaves following a first order reaction kinetics at both application rates. The amount of dissipation in 14 days was 93.37% and 91.62% for single and double doses respectively. Half life (T(1/2)) for degradation of thiacloprid in green tea leaves were observed to be 3.34 and 3.58 days at single and double doses respectively. Thiacloprid residues in processed tea ranged from 0.16 to 0.63 µg g(-1) on seventh day and no residues could be detected on 14th day at single dose. Infusion study indicated that thiacloprid did not infuse into tea liquor from processed tea. The limit of determination was found to be 0.05 µg g(-1).

Multiresidue analysis of organochlorine pesticides in milk, egg and meat by GC-ECD and confirmation by GC-MS.

A multiresidue method was developed and optimized for the quantification of organochlorine pesticides (OCPs) in milk, egg and meat samples. Sample extraction was performed by adopting QuEChERS principle and the extracts were cleaned-up dispersive solid-phase extraction with primary secondary amine after salting out with NaCl and MgSO(4). Analysis was carried out by gas chromatography coupled with electron capture detector and confirmation by gas chromatography-mass spectrometry. The performance of the method was investigated in terms of linearity, accuracy, precision, detection limit and quantification limit (LOQ). Good linearity was obtained, with correlation coefficients (r(2)) higher than 0.992. Mean recoveries were found in the ranges 72%-108%, 74%-101% and 75.27%-104.56% for the milk, egg and meat, respectively, RSD % turned out to range from 0.28% to 10.05%. The method developed was successfully tested on commercial milk, egg, and meat samples from the markets of Tamil Nadu (India), proving to be a useful tool in routine analysis of OCPs for monitoring purposes. None of the compounds of interest were observed above their respective LOQ.

Degradation dynamics of flubendiamide in different types of soils.

Residual dynamics of flubendiamide in three different types of soils were investigated under laboratory condition. Flubendiamide was applied at 5 and 10 µg g(-1) for each soil and samples drawn periodically were analyzed on HPLC. The results showed that the degradation of flubendiamide in soils were followed first-order kinetics and its average half-lives in three kinds of soils were ranged from 37.62 to 60.21 days. The persistence of flubendiamide in soils significantly increased in the order of coastal soil > red and lateritic soil > new alluvial.