The influence of nitrogen fertilizers on the yield of crop, as well as on the production and composition of the essential oil and some other chemical characteristics of thyme, was investigated. Different levels of fertilizers (N = 0, 45, 90, and 135 kg x ha(-)(1)) were applied. It was found that fertilizers increase thyme crop, but differences in the yield of essential oil were not remarkable. However, the use of certain amounts of nitrogen fertilizers resulted in higher yields of essential oil obtainable from the cultivation area unit (dm(3) ha(-)(1)). Totally, 61 constituents were identified in thyme essential oil by capillary GC and GC-MS. Thymol was the dominating compound in the all analyzed oils (44.4-58.1%), followed by p-cymene (9.1-18.5%), gamma-terpinene (6.9-18.9%), and carvacrol (2.4-4.2%). Differences in the percentage of these and other compounds in thyme herb cultivated under different fertilization doses were not significant; very slight changes in the percentage composition were detected after drying. Some variations in the amount of individual constituents expressed in arbitrary units per kilogram of herb (which is almost equivalent to mg x kg(-)(1)) were observed. The highest amounts of sugars and sucrose, in particular, were determined in the second year of thyme cultivation. Differences in the content of dry soluble substances were not meaningful, and there was no effect of nitrogen fertilizers on this chemical characteristic. Some effect of fertilization on the content of vitamin C and carotenes was observed in the first year of thyme cultivation. It was determined that nitrogen fertilizers influence the amount of nitrates, which was highest in the second-year-first-harvest.

These results indicate that the application of short-exposure UV-B radiation beneficially influenced both growth parameters and biochemical constituents in young and mature basil plants.

No abstract

The aim of this study was to investigate the possibility of using essential oils of Thymus vulgaris as an alternative preservative for chromed leather. The differences between the chemical composition of commercial and pure essential oils of thyme were determined. It was observed that these differences have an influence on the antibacterial activity of essential oils. Gram-positive bacteria were found to be more sensitive to the essential oils of thyme than Gram-negative bacteria. The bacteria Pseudomonas aeruginosa had a low sensitivity to the action of the selected essential oils of thyme, but the leather samples treated with the essential oils of thyme remained resistant to the action of these bacteria. As the main result of this study, it was concluded that the essential oil of thyme could be used as a preservation agent in the leather tanning industry. The leather preserved with 2-(thiocyanomethylthio)benzothiazole had weaker protection after four weeks compared to the samples treated with the essential oil of thyme when the amount of the used essential oil was not less than 3% of the wet-blue mass. The essential oil of thyme was the more active component in the mixture of essential oil and synthetic biocide used for the preservation of leather.

The study was done with the two peppermint (Mentha × piperita L.) cultivars -'Krasnodarskaja' and 'Peppermint', whose leaves were dried using different methods. Investigation of fresh and dried herbs was carried out according to the biochemistry and technology methods. Essential oil was extracted using the hydro distillation method, the amount of chlorophyll a and b was measured spectrophotometrically according to the Vernon method. The highest content of essential oil (0.77%) and chlorophyll (1.69%) was found in the cv. 'Peppermint'. Chlorophyll a to b ratio was different in the fresh peppermint leaves: in the cv. 'Peppermint' it was 1.35 and in the cv. 'Krasnodarskaja' -1.44. Peppermint leaves were dried using active ventilation, convection, infrared, vacuum, microwave, and sublimation methods. The quality of dried herbs depended on the properties of plants and drying techniques. The highest content of essential oil (0.64-0.68% of dry mass) was found in the variously dried peppermint leaves of the cv. 'Krasnodarskaja'. The lowest content of essential oil (0.08% and 0.065% of dry mass) was determined in microwave dried herbs. The highest content of chlorophyll was found in the lyophilized peppermint leaves (715.0 mg 100 g -1 of dry mass) of the cv. 'Peppermint'. Regardless of the drying method, significant differences between the ratio of chlorophyll a to b were observed in the dried herbs of the cv. 'Krasnodarskaja'. The fresh and dried peppermint samples of the cv. 'Peppermint' had the lowest brightness L* value (from 22.61 to 35.24) and the lowest yellowness b* values (from 9.35 to 17.00). The biggest changes in greenness a* value were in microwave dried peppermint leaves.