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Subject: Chemistry × End date: 2006 × Start date: 2006 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Quality of lemongrass (cymbopogon flexuosus) oils under different storage conditions and their nematicidal activity
    (CCSHAU, 2006) Yogesh Kumar Singh; Madan, V. K.
    Laboratory studies were conducted for qualitative and quantitative estimation of essential oils of lemongrass (Cymbopogon flexuosus) genotypes/varieties, effect of various storage methods on quality of essential oil of variety CKP–25 and nematicidal activity of aqueous extracts of essential oils of six genotypes/varieties of lemongrass against nematodes Meloidogyne javanica, Meloidogyne incognita and Rotylenchulus reniformis. The essential oils were analysed by GLC techniques employing Flame Ionization Detector (FID) equipped with Capillary Column Thermo TR–Wax (Polyethylene glycol). For storage studies the essential oil was kept for six months in glass, metal and plastic vials, replicated thrice under closed as well as open conditions. The quality of oils kept in different vials was estimated just before storage and subsequently after 2, 4 and 6 months of storage. The retention times for citral–a (geranial), citral–b (neral), geraniol and citronellal were 16.42, 15.53, 17.84 and 12.35 minutes, respectively. The oil content on Fresh Weight Basis (FWB) was in the range from 0.24 to 0.74%. The range of percent composition of various major and minor constituents were as follows: citral–a (47.1–52.4%), citral–b (30.3–37.5%), total citral (82.7–84.8%), geraniol (2.5–2.8%) and citronellal (0.8–1.1%). Citral–a (geranial), citral– b (neral), total citral, geraniol and citronellal contents in the essential oils decreased during storage period. The decrease in citral–a (geranial), citral–b (neral), total citral, geraniol and citronellal contents during storage was minimum in glass vials followed by plastic vials and metal (aluminium) vials. Between closed and open vials, the decrease in citral–a, citral–b, total citral, geraniol and citronellal contents was less in closed vials in comparison to open vials. The probable reason for degradation may be due to oxidation of citral–a, citral–b, geraniol and citronellal into their derivatives resulting in less concentration of these constituents in the essential oil. The nematicidal activity of aqueous extracts of essential oils of lemongrass was highest against the nematodes M. incognita followed by M. javanica and Rotylenchulus reniformis. The probable reason for nematicidal activity of aqueous extracts of lemongrass essential oils may be due to the presence of aldehydic group in major constituents (citral–a, citral–b) & minor constituents (citronellal) and alcoholic group (geraniol) in minor constituents. Keeping in view the storage studies under laboratory conditions, it can be inferred that essential oils of lemongrass can be kept in closed glass vials for less degradation in quality of essential oil and also these essential oils are effective in controlling the nematodes under laboratory conditions.
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    ThesisItemOpen Access
    Persistence and degradation behaviour of propiconazole in soil and water systems
    (CCSHAU, 2006) Chauhan, Reena; Beena Kumari
    Laboratory studies were carried out in clay loam soil and canal water treated with propiconazole, a triazole fungicide, to investigate the persistence and degradation behavior of propiconazole residues. During these studies, propiconazole 25 EC was applied @ 125 and 250 g a.i./ha in clay loam soil taken in the plastic pots under non-flooded and flooded conditions. Water was treated with propiconazole@ 0.0625 and 0.125μgml-1. Each treatment of soil and water was replicated thrice. The representative samples of soil and water were taken after 0 (1h), 3, 7, 15, 30, 60 and 90 days after treatments and processed for propiconazole residue analysis. The residues were estimated by GLC technique employing ECD equipped with SPB-5 (95%dimethyl /5%diphenyl polysiloxane) capillary column. Retention time of propiconazole was observed to 16.618 min and 16.742min.The dissipation was faster in non-flooded soil (half-life period; 51.90 and 53.26 days) as compared to flooded condition (half-life period, 55.85 and 57.69 days).The dissipation in water was faster as compared to soil. Half-life values at single and double doses in water were 35.78 and 38.22 days, respectively. The lower dose showed slightly faster dissipation as compared to higher dose irrespective of the soil and water systems. In soil as well as water, dissipation followed the first order kinetics. Keeping in view the dissipation pattern under laboratory conditions it can be inferred that although complete degradation of propiconazole was neither in soil nor in water yet keeping in view the low residues levels in 90 day studies, it can be applied in crop at field conditions.