Impact of soil type and temperature on dissipation dynamics of a new readymix formulation of halauxifen-methyl + pyroxsulam.

The persistence and dissipation of a new readymix formulation of halauxifen-methyl + pyroxsulam was investigated in three soils viz. red lateritic (Soil A), coastal saline (Soil B) and black soil (Soil C) under three incubation temperatures (20, 30 and 40° C). Soil samples were fortified at 1.0 (T1) and 2.0 (T2) mg kg- 1 doses separately for both compounds. The analytical methods showed satisfactory mean recovery, precision and linearity and therefore accepted for analysis. Both molecules followed single first-order kinetics. A significant influence of soil type on the persistence of both herbicides was observed. The order of stability of halauxifen-methyl was Soil A > B > C and for pyroxsulam was Soil B > C > A. Besides, a faster rate of dissipation of halauxifen-methyl and pyroxsulam was recorded at elevated temperatures, regardless of soil type. This research will help to understand the effect of temperature on the fate of the herbicide mixture in soils of diverse agro-climatic regions.

Validation of a Multiresidue Method for the Analysis of 86 Multiclass Pesticides in Litchi Fruit by Gas Chromatography-Tandem Mass Spectrometry.

BACKGROUND: Although India is an important producer of litchi fruit, there is hardly any validated method available for its pesticide residue analysis. This strongly warrants the need to standardize a simple multiresidue analytical method for efficient analysis of multiclass pesticides with specificity, sensitivity, and accuracy in a single chromatographic run in combination with MS determination. OBJECTIVE: The aim of this study was to develop and validate a rapid ethyl-acetate-based sample preparation method for a simultaneous determination of 86 pesticides in litchi fruit by using GC-tandem MS. METHODS: The method involved ethyl acetate as an extracting solvent and a combined salt system comprising sodium chloride and sodium sulphate for the organic layer separation. To obtain satisfactory recovery percentage of each pesticide studied here, this combination was selected for further validation based on selectivity, sensitivity, linearity, precision, and accuracy values. RESULTS: The correlation coefficient (r2) of studied pesticides ranged between 0.97 and 0.99 at six concentration levels from 5 to 250 ng/mL. Furthermore, the average recovery values were within 70 and 120%, with repeatability relative SD below 20% for all 86 pesticides at the LOQ level and with an appreciable Horwitz ratio distribution that ranged between 0.5 and 2. CONCLUSIONS: All data demonstrate that the proposed method is adequately linear, accurate, and repeatable. Therefore, it can be widely used in commercial laboratories for analyzing pesticide residues for both domestic and export purposes. The method is in support of protecting consumer health. HIGHLIGHTS: A large-scale multiresidue method is reported for simultaneous analysis of a wide range of pesticides in litchi. The method complies with the regulatory requirements in terms of sensitivity for maximum residue limit compliance. The performance of the method complied with the SANTE guidelines of analytical QC.

Phytotoxicity of glyphosate in the germination of Pisum sativum and its effect on germinated seedlings.

The present study evaluated the effects of glyphosate on Pisum sativum germination as well as its effect on the physiology and biochemistry of germinated seedlings. Different physico-chemical biomarkers, viz., chlorophyll, root and shoot length, total protein and soluble sugar, along with sodium and potassium concentration, were investigated in germinated seedlings at different glyphosate concentrations. This study reports the influence of different concentrations of glyphosate on pea seeds and seedlings. Physicochemical biomarkers were significantly changed by glyphosate exposure after 15 days. The germination of seedlings under control conditions (0 mg/L) was 100% after 3 days of treatment but at 3 and 4 mg/L glyphosate, germination was reduced to 55 and 40%, respectively. Physiological parameters like root and shoot length decreased monotonically with increasing glyphosate concentration, at 14 days of observation. Average root and shoot length (n=30 in three replicates) were reduced to 14.7 and 17.6%, respectively, at 4 mg/L glyphosate. Leaf chlorophyll content also decreased, with a similar trend to root and shoot length, but the protein content initially decreased and then increased with an increase in glyphosate concentration to 3 mg/L. The study suggests that glyphosate reduces the soluble sugar content significantly, by 21.6% (v/v). But internal sodium and potassium tissue concentrations were significantly altered by glyphosate exposure with increasing concentrations of glyphosate. Biochemical and physiological analysis also supports the inhibitory effect of glyphosate on seed germination and biochemical effects on seedlings.