Browsing by Author "Mandal, Kousik"
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ThesisItem Open Access Absorption and Metabolism of Fipronil in Sugarcane and its Persistence in Soil(2012) Mandal, KousikThe persistence and metabolism of fipronil in sugarcane leaves and soil were studied following application of fipronil @ 75 and 300 g a.i. ha-1. Samples of sugarcane leaves and soil were collected at various time intervals and analysed by using Gas Liquid Chromatograph (GLC) and confirmed by Gas Liquid Chromatograph –Mass Spectrometry (GC-MS). The total residues of fipronil and its metabolites in sugarcane leaves after 7 days of its application @ 75 and 300 g a.i. ha-1 were found to be 0.26 and 0.66 mg kg-1, respectively.These residues could not be detected after 60 and 90 days following the application of fipronil at lower and higher dosages, respectively. The samples of sugarcane juice did not reveal the presence of fipronil residues at harvest. Maximum residues of fipronil and its metabolites in soil samples were found to be 0.025 and 0.098 mg kg-1 collected 7 days after the application of fipronil @ 75 and 300 g a.i. ha-1, respectively. These residues could not be detected after 210 and 240 days following the application of fipronil at lower and higher dosages, respectively. In laboratory experiment, the residues of total fipronil in sandy loam, loam and clay loam after 7 day of its application @ 100 mg kg-1 were found to be 74.30, 75.80 and 82.50 mg kg-1, respectively. The persistence of fipronil was found to be almost equal in all types of soil. Three soil microbes viz. Bacillus firmus, Bacillus aerophilus and Bacillus thuringiensis were isolated and identified from sugarcane fields. These were found to be very effective in degradation of fipronil.ThesisItem Open Access EFFECTS OF INORGANIC PHOSPHORUS FRACTIONS UNDER DIFFERENT TILLAGE OPERATIONS ON WHEAT (Triticum aestivum) IN AN ACID SOIL OF WEST BENGAL(2014) Mandal, Kousik; Mukhopadhayay, D.ThesisItem Restricted Studies on persistence of fenazaquin and spirotetramat in chilli and soil.(Punjab Agricultural University, Ludhiana, 2022) Himani; Mandal, KousikTrials were conducted for two years for studying the dissipation and persistence of fenazaquin and spirotetramat in chilli and soil following application of Fenazaquin 10 EC @ 125, 156.25 and 250 g a.i. ha-1 and Spirotetramat 15.31 OD @ 60, 75 and 120 g a.i. ha-1. The limit of quantification (LOQ) and (LOD) were 0.01 and 0.003 mg kg-1. The residues of fenazaquin dissipated more than 90 per cent in 20 and 10 days in green chilli and soil, respectively at recommended dose. The residues of spirotetramat and its metabolites reached below the LOQ after 15 and 3 days in green chilli and soil, respectively at the recommended dose. Waiting period was calculated to be 3, 5 and 8 days for green chilli after application of fenazaquin at the 125, 156.25 and 250 g a.i. ha1 . One day waiting period is estimated after treatment of green chilli with spirotetramat at the three doses. The processing factor for fenazaquin residues in red chilli after dehydration was estimated to be 2.08 at recommended dose for both the years. Dipping of chilli fruits in baking soda (5%) and boiling proved effective in reducing the residues of fenazaquin and spirotetramat. The activity of the amylase, invertase, acidic phosphatase was not affected by these pesticides while the dehydrogenase activity was reduced. The activity of the alkaline phosphatase and urease was affected after the application of fenazaquin and spirotetramat.