The effects of different UV-B radiation intensities on morphological and biochemical characteristics in Ocimum basilicum L.

BACKGROUND: The effects of short-term ultraviolet B (UV-B) irradiation on sweet basil (Ocimum basilicum L. cv. Cinnamon) plants at the 3-4 leaf pair and flowering stages were examined in controlled environment growth chambers. Plants were exposed to 0 (reference), 2 and 4 kJ UV-B m(-2) day(-1) over 7 days. RESULTS: Exposure of basil plants to supplementary UV-B light resulted in increased assimilating leaf area, fresh biomass and dry biomass. Stimulation of physiological functions in young basil plants under either applied UV-B dose resulted in increased total chlorophyll content but no marked variation in carotenoid content. At the flowering stage the chlorophyll and carotenoid contents of basil were affected by supplementary UV-B radiation, decreasing with enhanced UV-B exposure. Both total antioxidant activity (2,2-diphenyl-1-picrylhydrazyl free radical assay) and total phenolic compound content were increased by UV-B light supplementation. Young and mature basil plants differed in their ascorbic acid content, which was dependent on UV-B dose and plant age. UV-B radiation resulted in decreased nitrate content in young basil plants (3-4 leaf pair stage). CONCLUSION: 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.

Characterization of steam volatiles in the essential oil of black currant buds and the antioxidant properties of different bud extracts.

Currently essential oil from black currant ( Ribes nigrum L.) buds is mainly used as a valuable perfumery ingredient. This study reports more comprehensive characterization of dormant buds of various black currant ( Ribes nigrum L.) cultivars which are grown in Northern European countries. Essential oils were isolated from the buds by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), GC-flame ionization detection (GC-FID), and GC--olfactometry (GC-O). The most abundant compounds in black currant bud essential oil were sabinene, delta-3-carene, and terpinolene. The most frequent descriptors of the essential oil components assessed by GC-O were "woody", "terpene", "fruity", "sweet", "citrus", "herbaceous", "pine", "green", "oily", "herbal", and "musty". The residues obtained after hydrodistillation were separated into liquid and solid fractions. The solid fraction was dried and extracted with acetone (AE), while the liquid fraction (water extract) was divided in two parts, one of which was spray-dried (SDWF extracts) and the other freeze-dried (FDWF extract). In addition, a portion of whole frozen buds was extracted with methanol (ME). The radical scavenging capacity (RSC) of black currant bud extracts varied in a wide range; in the DPPH * reaction system FDWF at the applied concentration scavenged 43-79%; SDWF, 54-80%; AE, 16-36%; ME, 42-60% of radicals; while in the ABTS *+ reaction system the RSC was 39-72, 38-53, 1-5, and 30-49%, respectively. The total amount of phenolic compounds expressed in gallic acid equivalents in FDWF varied in the range of 132-192 mg/g; in SDWF, 140-209 mg/g; in AE, 49-107 mg/g; and in ME extracts, 111-180 mg/g.

Influence of nitrogen fertilizers on the yield and composition of thyme (Thymus vulgaris).

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.