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Studz of direct and indirect plasma application on onion seeding bulbs
Krejsová, Lenka ; Enev, Vojtěch (referee) ; Krčma, František (advisor)
Nowadays, agriculture is based on conventional methods that involve the application of pesticides, agricultural chemicals and fertilizers. These substances have a negative impact on nature and human health, so more environmentally friendly methods are being sought. This thesis deals with the analysis of fragrances in onions treated with plasma before planting. The treatment was carried out to see if it would improve onion growth while maintaining or increasing the fragrance content. The theoretical part deals with the soil and it is characterization methods, plasma, quantitative and qualitative methods for the determination of volatile substances. It contains the principles of UV-VIS spectrometry, atomic absorption spectrometry (AAS), mass spectrometry (MS) as well as tandem connection of gas chromatography with mass spectrometry (GC–MS). The experimental part was carried out over a period of three years at 22 sites. The preparation and analysis of soil samples are described, which was also evaluated. Furthermore, the procedures for treating the bulbs with corona discharge and plasma-activated water before planting were described. In total, four treatment variants were carried out and bulbs from the fifth variant were not additionally treated. Each treatment variant was planted in four replications of ten bulbs each. Twenty selected grown onions from one site were individually converted to liquid samples and the saturated vapor was analysed by proton transfer reaction time of flight mass spectrometry (PTR–TOF–MS). Thanks to this analysis, the concentrations of volatile substances were determined. Some samples were analyzed by gas chromatography with mass spectrometer as detector to identify the compounds. Subsequently, the data were processed and evaluated. From the results obtained, it is evident that plasma treatment can be useful for the treatment of onions in agriculture, because it confirmed harvest increase without decrease of fragrances concentrations. Thus, it is necessary to carry out experiments on a larger scale in the future.
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