Kang, Balpreet KaurRasool, Rozy2022-12-042022-12-042021Rasool, Rozy (2021). Uptake and Metabolism of Thiamethoxam in Wheat and its Persistence in Soil (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810190342The persistence and metabolism of thiamethoxam in wheat and soil was studied following thiamethoxam application as seed treatment and foliar application. Wheat and soil samples were analyzed by Liquid Chromatography-Tandem Mass Spectrometry. During 2018-19, total residues of thiamethoxam and its metabolites were found to be 2.64 and 9.75 mg kg-1 in wheat leaves collected at 20 days after seed treatment with thiamethoxam-Cruiser 70WS @ 0.7 and 2.8 g a.i. kg-1, respectively, however, during 2019-20, the residues were 2.52 and 9.71 mg kg-1, respectively, and reached below limit of quantification (LOQ) at 90 days after seed treatment for both the dosages during both the years. In soil samples, these residues were found to be below LOQ after 45 days after seed treatment for both the dosages during both the years. During 2018-19, the initial deposits of thiamethoxam and its metabolites were found to be 3.69 and 14.03 mg kg-1 in leaves collected at 0 (2hrs after application) day after foliar application of thiamethoxam-Actara 25WG @ 12.5 and 50.0 g a.i. ha-1, respectively, however, during 2019-20, the residues were 3.79 and 14.36 mg kg-1, respectively. The residue in leaves reached below LOQ at 30 and 45 days after foliar application of thiamethoxam @ 12.5 and 50.0 g a.i. ha-1, respectively. These residues in soil dissipated to below LOQ after 30 days after foliar application for both the dosages during both the years. The samples of straw and grain did not reveal the presence of thiamethoxam residues at harvest during both the years. Microbial isolates isolated from soil, Bacillus safensis, B. pumilus, B. megaterium, B. velezensis, Aspergillus sp., Cladosporium velox, Aspergillus flavus, Streptomyces sp. 1 and Streptomyces sp. 2. screened for thiamethoxam degradation were found to be effective in degradation of thiamethoxam. Thiamethoxam degradation in soils amended with 50, 100 and 150 mg kg-1 thiamethoxam was 86.68 to 89.41 per cent, 97.99 to 98.70 per cent and 85.99 to 87.63 per cent by Bacillus safensis, Aspergillus sp. and Streptomyces sp. 1, respectively, which were the most efficient microbial isolates.EnglishThesis