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Valtcho D. Zheljazkov, Charles L. Cantrell, Tess Astatkie and Ekaterina Jeliazkova

units for 60 min as described previously ( Gawde et al., 2009 ; Zheljazkov et al., 2010a , 2010b ). The essential oils were measured on an analytical scale and kept in a freezer at –14 °C until the analyses. The essential oil content was calculated as

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Valtcho D. Zheljazkov, Tess Astatkie, Thomas Horgan, Vicki Schlegel and Xavier Simonnet

, 1973 ). Like with other aromatic plants, A. annua essential oil content and composition is modified by genotype and the environment ( Tzenkova et al., 2010 ), by distillation method ( Scheffer, 1993 ), and by other factors. A recent report ( Ferreira

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Noelle J. Fuller, Ronald B. Pegg, James Affolter and David Berle

difficult to differentiate between available seed stock or know which ones should be grown to achieve maximum yield and quality. Furthermore, details concerning yield, essential oil content, and eugenol concentration are lacking for many of the USDA

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Bahlebi K. Eiasu, Puffy Soundy and J. Martin Steyn

from twice a day to once a day either maintained or enhanced essential oil yield per plant. Such a result was probably the result of a tendency of essential oil content (percent oil on herbage fresh weight basis) to increase with a decrease in

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Valtcho D. Zheljazkov, Vasile Cerven, Charles L. Cantrell, Wayne M. Ebelhar and Thomas Horgan

harvested area of ≈32,076 ha ( USDA, NASS, Crop Report, 2007 ). The U.S. peppermint oil is considered of high quality and U.S. essential oil broker companies have dominated the peppermint essential oil market. The essential oil content and composition of

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Renee G. Murray and James E. Simon

Essential oil content of Ocimum basilicum, cv. sweet basil, increases with plant maturity. The increase in essential oil content may correspond to the formation of glandular trichomes during leaf expansion. Greenhouse grown plants were harvested every 2 weeks. Leaves were grouped according to size, examined with a stereo microscope, and trichome densities compared. Results indicate that trichome formation continues throughout leaf expansion. In young basil plants, leaves ranged in size from 2-30cm2 Highest density (416 trichomes/cm2) occurred in leaves 2–6c m2. Prior to open bloom, leaves ranged in size from 2-49cm2. Highest density occurred in leaves 18-24c m2. In flowering plants leaves ranged in size from 2-34cm2, yet there was NSD in trichome density in leaves of different sizes. Analysis of the entire leaf surface of plants at each harvest showed the greatest density of trichomes in plants at full bloom (280 trichomes/c m2). All leaves have visible glandular trichomes. These glandular trichomes are most likely formed both prior to and during leaf expansion.

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W. Letchamo, C. Mengle and A. Gosselin

The content of essential oil, thymol, and carvacrol in a thymol-type of clonally selected thyme plants during different developmental stages were investigated under greenhouse and field conditions. Plants in the greenhouse were grown from July to November, under natural light and natural light supplemented by a PPF of 200 μmol·m–2·s–1, provided by HPS lamps, while plants in the field were studied from June to November. Shoot yield and the accumulation of the active principles from greenhouse-grown plants were determined by harvesting the plants at 40-, 60-, and 120-day intervals, while field-grown plants were harvested in August, September, October, and November. Essential oil content, qualitative and quantitative changes in the oil were determined by subjecting the samples to steam distillation and subsequent gas chromatographic analysis. There were important changes in shoot yield, essential oil, thymol, and carvacrol content in the course of plant development. After 120 days of growth under greenhouse conditions, the essential oil content increased by >150%, while thymol content increased by ≈200% compared with the 40-day-old plants. We found some differences in oil content, thymol, and carvacrol accumulation between field- and greenhouse-grown plants. The pattern of crop yield and the accumulation of the major active substances under field and greenhouse conditions are presented and discussed.

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M. Rawgappa, H.L. Bhardwaj, A.I. Mohamed, M.E. Showhda and M.E. Kraemer

Thirty-five mint accessions were evaluated during 1993 for agronomic characteristics (leaf texture, color, and pubescence), plant vigor, cold hardiness, insect population interactions, and contents of essential oils, ash, and total protein. These accessions were obtained from National Clonal Germplasm Repository, Corvallis, Oregon during 1992. The rhizomes were planted in the greenhouse on April 2, 1992 and transplanted to the field on May 29, 1992 as a randomized complete block design with three replications. The chemical composition data from whole plants indicated that ash content was dependent upon location from which an accession was collected, ploidy level (diploid vs. polyploid), type of mint (peppermint vs. spearmint), and genetics (hybrid vs. non-hybrid). Diploid accessions had significantly higher essential oil content. The protein content was higher in peppermint types than spearmint types. The hybrid accessions had lower protein content in comparison to non-hybrids.

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Denys J. Charles and James E. Simon

The curry plant [Helichrysum italicum (Roth) G. Don in Loudon ssp. italicum or H. angustifolium (Lam.) DC (Asteraceae)], a popular ornamental herb with a curry-like aroma, was chemically evaluated to identify the essential oil constituents responsible for its aroma. Leaves and flowers from greenhouse-grown plants were harvested at full bloom. Essential oils were extracted from the dried leaves via hydrodistillation and the chemical constituents analyzed by gas chromatography (GC) and GC/mass spectrometry. The essential oil content was 0.67% (v/w). Sixteen compounds were identified in the oil and included: neryl acetate (51.4%), pinene (17.2%), eudesmol (6.9%), geranyl propionate (3.8%),β-eudesmol (1.8%), limonene (1.7%), and camphene (1.6%). While the aroma of the curry plant is similar to that of a mild curry powder, the volatile chemical profile of the curry plant does not resemble that reported for commercial curry mixtures.

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Kelly M. Bowes and Valtcho D. Zheljazkov

Field and laboratory experiments were conducted at two sites in Nova Scotia during 2001 and 2002 to assess the potential to grow fennel (Foeniculum vulgare Mill.) as an essential oil crop in the Maritime region of Canada. Three cultivars—`Shumen', `Berfena', and `Sweet Fennel'—and two seeding dates—24 May and 8 June—were evaluated. Essential oil yields and composition were determined and compared to commercially available fennel essential oil from the U.S. The highest herbage yields were produced by `Shumen' from the earlier seeding date. Essential oil content and yields were lowest in `Sweet Fennel' and highest in `Shumen'. The major component of the essential oil was anethole, 47% to 80.2%. Other major components of the essential oil were methyl chavicol, fenchone, α-phellandrene, α-pinene, ortho cymene, β-phellandrene, fenchyl acetate, β-pinene, and apiole. The essential oil composition was unique to each cultivar. The highest methyl chavicol content was in `Shumen', while the highest concentration of phellandrene, fenchyl acetate and apiole were detected in `Sweet Fennel' oil. Fenchone, ortho cymene, β-pinene, α-phellandrene, and α-pinene were the highest in `Berfena'. The composition of the oil was similar to the commercially purchased oil and met industry requirements of oil composition. The results suggest there is potential to grow fennel as an essential oil crop in Nova Scotia.