R. J. Fletcher

Citronellol: geraniol ratios and temperature in geranium (Pelargonium hybrid)

Concentrations of citronellol and geraniol in essential oil from rose geranium (Pelargonium hybrid) were monitored monthly over four years using gas chromatography-mass spectrometry. Geraniol concentrations fell in winter and citronellol concentrations increased in spring. The citronellol/geraniol (C:G) ratio was a more sensitive indicator of change in oil composition than the concentration of either alcohol in isolation. C:G ratios rose sharply if the minimum air temperature (T-min) fell below 5.5 degrees C for any time during the 5 d prior to monthly harvesting, A nonlinear model is proposed to predict the C:G ratio at any T-min. High C:G ratios indicated cold stress in geranium plants.

Comparison in the γ-Lactone Content of Oils and Extracts from White Cypress Pine (Callitris glaucophylla Thompson & Johnson)

Abstract The γ-lactones found in white cypress-pine (Callitris glaucophylla) wood are compounds implicated in termiticidal activity. Distilled oils and solvent extracts from an cypress-pine contained different amounts of γ-lactones. The distilled oils were poor in γ-lactones ( 45%). Oils and extracts contained (-)eudesma-1,4(15),11-triene, β-selinene and α-selinene previously found in other Callitris oils. Six γ-lactones were identified using GC/MS. They were callitrin, dihydrocolumellarin, callitrisin, columellarin, germacranolide and dihydrocallitrisin. Mass spectroscopy indicated three previously unidentified lactones; two were isomers of callitrisin and the third, an isomer of germacranolide. Chiral gas chromatography separated many enantiomers of lower boiling point components of the distilled oil.

Chiral Excess: Measuring the Chirality of Geographically and Seasonally Different Geranium Oils

Essential oils from Australian grown rose geranium (Pelargonium hybrid) G1 clone, were analyzed regularly over a three year period using chiral and normal column gas chromatography. The G1 oil was compared to other commercial geranium oils using ten key chiral compounds. Comparisons were made using the new concept called chiral excess (CE), the first eluting enantiomer minus the second eluting enantiomer, and total excess (TE), the sum of all the CEs. This concept allowed the chirality of geranium oils to be expressed as a single number. TE was used to help distinguish between 18 geographically different and 24 seasonally different commercial oils. Applications of TE include classification of other chiral-containing oils and the detection of adulterants in essential oils.

Osmoregulation in birdseed millet under conditions of water stress II. Variation in F3 lines of Setaria italica and its relationship to plant morphology and yield

Variation in osmoregulation is reportedduring water stress for 40 F3 families ofSetaria italica L. (Foxtail millet).The lines were derived from a cross betweentwo genotypes known to differ in thischaracter. A clear separation was observedinto 23 low and 17 high osmoregulation F3families with coefficient variation 19.6%.Osmoregulation was not associated withplant height, length or width of flag leaf,length of panicle exertion, length or widthof inflorescence or dry matter, but wassignificantly associated with grain yield,grain number and harvest index. Mean yieldand harvest index for the highosmoregulation group were 1.58 and 1.57times greater, respectively, than yield andharvest index for the low osmoregulation.

Osmoregulative capacity in birdseed millet under conditions of water stress. I. Variation in Setaria italica and Panicum miliaceum

Experiments involving 14 accessions of Panicum miliaceum L. (Proso millet) and 11 accessions of Setaria italicaL. (Foxtail millet) have demonstrated variability in the degree of osmoregulative capacity among these accessions. Birdseed millet is generally claimed to be sensitive to drought stress, apparently because of a shallow root system. Accessions with high osmoregulative capacity demonstrate at least some drought tolerance. Osmoregulative capacity was measured on flag leaves of headed millet plants in pots undergoing water stress in a controlled environment chamber. Osmoregulative capacity was determined from the relationship between osmotic potential and leaf water potential; and the logarithmic relationship between osmotic potential and relative water content. The group of accessions of S. italica showed an overall level of osmoregulative capacity which was greater than that observed for the group of P. miliaceum accessions. Four accessions of S. italica(108042, 108463, 108541 and 108564) and one accession of P. miliaceum (108104)demonstrated high osmoregulative capacity. Differences of 1.05 MPa or more between observed and estimated osmotic potential were found at relative water contents of80 % among these accessions. The extent of osmoregulative capacity was associated with osmotic potential at full turgor and the rate of decline in osmotic potential as leaf water potential declined.

Esters in Australian geranium oil (Pelargonium hybrid)

This paper is the first detailed report of straight chain and branched esters in Australian geranium oil. Hydrodistillation of 41 samples of Australian-grown rose geranium (Pelargoniun hybrid) produced oils containing four detectable parent alcohols; 2-phenylethanol (0.9%), citronellol (16.9%), nerol (0.9%) and geraniol (11.3%) and 47 of their esters. The esters present were formates (19.7%), tiglates (4.0%), propanoates (2.4%), butyrates (1.6%), iso-esters (1.2%), acetates (0.8%) and other esters (0.3%). Gas chromatography using a non-polar BPX-5 column, separated the esters with citronellyl esters emerging regularly before neryl (ΔRI = 9) and geranyl (ΔRI = 33) esters. Iso-esters emerged before their straight chain namesakes (ΔRI = −50).

A New Chemovar of Gympie Messmate (Eucalyptus cloeziana F. Muell.) Containing α-Pinene and Tasmanone

Abstract A new essential oil from Eucalyptus cloeziana is described, which contains a combin ation of compounds found in two chemovars previously known. This new chemovar contains α-pinene (62%), predominantly present as (+)-α-pinene, and tasmanone (6%). Limonene and linalool were present as (+)-enantiomers. Tasmanone is a possible therapeutic compound.

Ozothamnus diosmifolius (Vent.) DC flower and leaf essential oils

Abstract Essential oils of rice flower, Ozothamnus diosmifolius, were analyzed by capillary gas chromatography-mass spectrometry. Flower oil contained β-pinene (28.4%) and 1,8-cineole (28.2%), while the leaf oil contained α-pinene (26.0%), β-pinene (11.6%) and 1,8-cineole (22.2%). Both oils had small amounts of spathulenol (4.1% and 5.2%, respectively).

A New Essential Oil from Eucalyptus dura L.A.S. Johnson & K.D. Hill

Hydrodistillation of leaves of a new species of eucalypt, Eucalyptus dura, produced an oil rich in β-phellandrene (16.4%) and 1,8-cineole (22.6%). Chirality of the oil was unusual as most chiral compounds were represented by only one enantiomer. The monoterpenes α-pinene and limonene had both enantiomers present. The high β-phellandrene and 1,8-cineole content of the oil makes it suitable for use as a bacteriostat.