Browsing by Author "ANU KUMARI"
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ThesisItem Open Access Biobeds for Azoxystrobin and Imidacloprid Rinsate Disposal(DIVISION OF AGRICULTURAL CHEMICALS ICAR-INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI –, 2018) ANU KUMARI; Neera SinghImproper disposal of leftover pesticide from sprayer operation or cleaning and spills during sprayer filling can contaminate soil and water bodies. The biobed, which contain a biologically active biomixture, provides a simple low cost method for on-farm treatment of pesticide wastes. The composition and properties of a biomixture used in a biobed are decisive for pesticide sorption and degradation. Four rice straw (RS)/corn cob (CC) and peat (P)/compost (C) based biomixtures viz. RS+C, RS+P, CC+P and CC+C, were used to study adsorption and degradation of azoxystrobin and imidacloprid. The kinetics and adsorption of azoxystrobin and imidacloprid on biomixtures was studied using batch method. The kinetics data was modelled using pseudo first-order (PFO), pseudo second-order (PSO), Elovich and intra-particle diffusion (IPD) models. Results (r2 Adj values) suggested that modified Elovich model was the best suited to explain the kinetics of imidacloprid sorption while different models explained azoxystrobin sorption kinetics in different biomixtures (PFO in RS+C and RS+P; PSO in CC+P and Elovich in CC+C). Biomixtures varied in their capacity to adsorb both pesticides and the adsorption coefficient (Kd) values were 116.8-369.24 (azoxystrobin) and 24.2-293.4 (imidacloprid). Compared to the Langmuir isotherm the Freundlich isotherm better explained the adsorption of both pesticides. Comparison analysis of the linear and nonlinear method for estimating the Freundlich adsorption constants suggested that the nonlinear Freundlich equation better explained the adsorption. Degradation of azoxystrobin and imidacloprid in biomixtures was studied and role of biomixture conditioning, moisture content and pesticide concentration was evaluated. Results indicated that biomixture condition affected pesticide degradation, but effect was significant on imidacloprid degradation where 2.5 to 9 times decrease in half-life were observed. Increasing the moisture content from 60% to 80% water holding capacity increased degradation of both pesticides. Degradation of both pesticides slowed down with increase in the initial concentration in biomixtures. Conditioning of biomixture increased microbial biomass carbon (1.2 - 4 times) and dehydrogenase activity (9-16 times). Azoxystrobin and imidacloprid application showed no adverse effect on the microbial biomass carbon, dehydrogenase and fluorescein diacetate activity. Retention and degradation of azoxystrobin and imidacloprid was studied in the constructed biobeds using RS+C and CC+C biomixtures and 2 applications of mixture of both pesticides (10,000 µg each) at 45 days intervals were made. None of the pesticide was detected in the leachate. Imidacloprid was completely degraded after both applications in both biobeds, while azoxystrobin did not degrade completely. Out of total 20,000 µg of azoxystrobin applied 81.5 and 68.1% was degraded in the RS+C and CC+C biobeds, respectively. Except for inhibition of the dehydrogenase activity in the CC+C biobed, no adverse effect of pesticide application on microbial parameters was observed. The study suggested that pesticide degradation was affected by the biomixture conditioning, moisture level and pesticide concentration. The RS+C biomixture, prepared using low cost and easily available materials, can be used in depuration systems for pesticide rinsate disposal. Keywords : Azoxystrobin, Imidacloprid Rinsate, Biomixtures, DehydrogenaseThesisItem Open Access DEVELOPMENT OF CONTROLLED RELEASE FORMULATIONS OF AZOXYSTROBIN BASED ON AMPHIPHILIC POLYMERS(DIVISION OF AGRICULTURAL CHEMICALS INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI –, 2014) ANU KUMARI; Jitendra KumarAmphiphilic polymers were synthesized and screened using poly(ethylene glycols) (PEGs) of different molecular weights, viz. 1000, 1500, 2000 and 4000 as hydrophilic block and linkers namely azelaic acid, terephthaleic acid, suberic acid and glycolic acid as hydrophobic block in the presence of catalyst Conc. H2SO4. Synthesized polymers were characterized by using 1H NMR, 13C NMR and IR spectroscopy. Micellar sizes of the polymers were determined using Dynamic Light Scattering (DLS) which ranged from 32.1–308 nm. Transmission Electron Microscope (TEM) results confirmed the findings of DLS. Critical Micelle Concentrations (CMC) of the synthesized polymers were determined using electrical conductivity meter which ranged from 105 to 650 mg L−1 . Amphiphilic copolymers, synthesized from poly(ethylene glycols) and various aliphatic and aromatic diacids and monoacids(glycolic acid), which self assemble into nano-micellar aggregates in aqueous media, were used to develop controlled release (CR) formulations of azoxystrobin Methyl (E)-2-{2[6-(2-cyanophenoxy)pyrimidin-4-yloxy] phenyl}-3- methoxyacrylate using encapsulation technique. Formulations were characterized by Infrared (IR) spectroscopy, Dynamic Light Scattering (DLS) and Transmission Electron Microscope (TEM). Encapsulation efficiency and loading capacity of polymers were checked. Accelerated storage test of the developed formulations were carried out to check the stability of a.i. in formulations. The kinetics of azoxystrobin release in water from the different formulations was also studied. The release of a.i. from the commercial formulation was faster than the CR formulations. The diffusion exponent (n value) of azoxystrobin, in water ranged from 0.21 to 0.56 in the tested formulations. The time taken for release of 50 % of azoxystrobin ranged from 2.05 to 7.63 days for the CR formulations. The bioefficacy of the prepared CR formulations was evaluated in vitro against major pathogens of rice namely Rhizoctonia solani and Fusarium fujikuroi and also in pot experiment against Fusarium fujikuroi along with a commercial formulation in a glass house of Indian Agricultural Research Institute (IARI), New Delhi. Most of the CR formulations of azoxystrobin provided superior control of both fungi compared to commercial formulation and control. Most of the developed CR formulations recorded higher efficacy over commercial formulation and control. The percent inhibition ranged from 55.4-86.0% and 55.8-87.5% against Rhizoctonia solani and Fusarium fujikuroi respectively from different CR formulation of azoxystrobin obtained in in-vitro study. In the pot experiments all the treatments resulted in a significant reduction of foolish seedlings infestation as compared to untreated control. The seedling treated formulation based on amphiphilic polymer Poly [poly (oxyethylene-4000)-oxy glycoyl] and Poly [poly (oxyethylene-1500)-oxyglycoyl] with recommended dose of azoxystrobin i.e. @ 1000 ppm against Fusarium fujikuroi showed best performance in terms of number of survived seedlings compared to commercial formulation. The study revealed that the CR products of the azoxystrobin may be used for efficient pest management of rice