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Essential oils are natural antimicrobials that have the potential to provide a safer alternative to synthetic antimicrobials currently used in the food industry. Therefore, the aim of this study was to evaluate the antimicrobial and antioxidant activities of essential oils from white wormwood, rose-scented geranium and bay laurel against Salmonella typhimurium and Escherichia coli O157:H7 on fresh produce and to examine consumer acceptability of fresh produce treated with these essential oils. Our results showed that essential oil derived from rose-scented geranium exhibited the most effective antimicrobial activity at the same and similar minimum inhibition concentration levels (0.4%, v/v and 0.4% and 0.5%, v/v) respectively against Salmonella typhimurium and Escherichia coli O157:H7. All three essential oils showed antioxidant properties, with the highest activity occurring in bay laurel essential oil. In a sensory test, tomatoes, cantaloupe and spinach sprayed with 0.4% rose-scented geranium essential oil received higher scores by panelists. In conclusion, rose-scented geranium essential oil could be developed into a natural antimicrobial to prevent contamination of Salmonella typhimurium and Escherichia coli O157:H7 in fresh produce, plus this oil would provide additional health benefits due to the antioxidant properties of its residue.

A field experiment was conducted on rose-scented geranium (Pelargonium sp.) in Pretoria, South Africa, to evaluate plant response to liming on acidic soils. Treatments were dolomitic limestone at 0 (control), 2, 4 and 6 t/ha, laid out as a randomized complete block design. Soil pH was not influenced by liming for any of the treatments at the first harvest, whereas at the second, third and fourth harvests an increase in pH was observed for all the limed treatments. At the time of the first harvest, plants did not respond significantly to 2 and 4 t/ha of liming, but responded positively to 6 t/ha, with higher herbage yield compared with the control and 2 t/ha lime treatments. At the second, third and fourth harvests fresh herbage and essential oil yield increased significantly due to liming. The differences among limed treatments were not significant for fresh herbage and essential oil yield. Cumulative fresh herbage and essential oil yields of all harvests were higher on the limed treatments than the contr...

Chemical fingerprinting of commercial Pelargonium capitatum (Geraniaceae) essential oil samples of south African origin was performed by GC, GC/MS, and (13) C- and (1) H-NMR. Thirty-seven compounds were identified, among which citronellol (32.71%) and geraniol (19.58%) were the most abundant. NMR Spectra of characteristic chemicals were provided. Broad-spectrum bioactivity properties of the oil were evaluated and compared with those of commercial Thymus vulgaris essential oil with the aim to obtain a functional profile in terms of efficacy and safety. P. capitatum essential oil provides a good performance as antimicrobial, with particular efficacy against Candida albicans strains. Antifungal activity performed against dermatophyte and phytopathogen strains revealed the latter as more sensitive, while antibacterial activity was not remarkable against both Gram-positive and Gram-negative bacteria. P. capitatum oil provided a lower antioxidant activity (IC(50) ) than that expressed by thyme essential oil, both in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and β-carotene bleaching tests. Results in photochemiluminescence (PCL) assay were negligible. To test the safety aspects of P. capitatum essential oil, mutagenic and toxicity properties were assayed by Ames test, with and without metabolic activation. Possible efficacy of P. capitatum essential oil as mutagenic protective agent against NaN(3) , 2-nitrofluorene, and 2-aminoanthracene was also assayed, providing interesting and significant antigenotoxic properties.

Effective irrigation management in arid and semi-arid regions, like South Africa, could increase crop yield and thereby improve productivity of scarce fresh water resources. Experiments were conducted at the Hatfield Experimental Farm of the University of Pretoria, South Africa, from 2004 to 2006, to investigate the effect of soil water depletion regimes on rose-scented geranium (Pelargonium capitatumP. radens cv. Rose) essential oil yield, essential oil composition and water-use efficiency in an open field and a rain shelter. Four maximum allowable soil water depletion levels (MAD), 20, 40, 60 and 80% of the plant available soil water (ASW) in the top 0.8 m root zone, were applied as treatments. Plant roots extracted most soil water from the top 0.4 m soil layer. Increasing the soil water depletion level to 60% and higher resulted in a significant reduction in herbage mass and essential oil yield. Water stress apparently increased the essential oil concentration (percentage oil on fresh herbage mass basis), but its contribution to total essential oil yield (kg/ha oil) was limited. Irrigation treatments did not affect essential oil composition. An increase in maximum allowable depletion level generally resulted in a decrease in leaf area and an increase in leaf to stem fresh mass ratio. Up to 28% of irrigation water could be saved by increasing maximum allowable depletion level of ASW from 20 to 40%, without a significant reduction in essential oil yield.

Response of plant growth and essential oil yield of rose‐scented geranium (Pelargonium capitatum × P. radens ’Rose') to withholding irrigation at different times of regrowth cycles was investigated at Hatfield Experimental Farm of the University of Pretoria, South Africa, from 2004 to 2007. No‐stress (control), and 1‐month withholding irrigation periods during the 2nd, 3rd, or 4th month of regrowth were applied as treatments. Herbage yield showed a significant reduction when the water stress period was imposed during the 3rd or 4th month of regrowth. A remarkable essential oil yield loss was observed only when the plants were stressed during the 4th month of regrowth. Essential oil content (% oil on fresh herbage mass basis) apparently increased in the stressed treatments, but total oil yield dropped as a result of lower herbage mass. Essential oil composition changes in response to irrigation withholding treatments were not consistent. Water‐use efficiency was not significantly affected by withh...

Pot experiments were conducted to investigate the effects of irrigation frequency and withholding irrigation during the week before harvesting on rose-scented geranium herbage yield and essential oil yield and composition. A factorial experiment with three irrigation frequencies (twice a day, once a day, and every second day) and two growth media (silica sand and sandy clay soil) were conducted in a tunnel. One week before harvest, irrigation was withheld for half of the pots in each treatment combination. In a glasshouse, sandy clay soil was used as growing medium, and five irrigation frequencies (everyday, everyday with 1-week irrigation withholding period, every second day, every third day, and every fourth day irrigation to pot capacity) were applied as treatments. Results showed that essential oil content (percent oil on fresh herbage weight basis) increased as the irrigation frequency decreased. Both herbage yield and essential oil yield positively responded to frequent irrigation. Thus, higher herbage and essential oil yields were obtained from the highest irrigation frequency. A 1-week stress period significantly increased total essential oil yield as well as oil content per fresh herbage weight. The results highlighted that conditions of high soil water availability followed by brief water stress just before harvesting would maximize rose-scented geranium essential oil yield. Citronellol and citronellyl formate tended to increase with an increase in the stress level, but the reverse was true for geraniol and geranyl formate. Other major essential oil components were unaffected by water stress.

Pelargonium capitatum (L.) L'Herit. is one of the parent species of the cultivar Rose grown on the Island of Reunion for the production of geranium oil. The aim of the project was to identify chemotypes which could be included in hybridization programs to ennoble the cultivar Rose Forty populations were selected along the coast of South Africa to describe the essential oil composition and identify possible chemotypes in P. capitatum. A multivariate statistical analysis was performed on the essential oil data. Examination of the composition of the oils proved the species to display high levels of essential oil variation which allows for the species to be divided into eight chemotypes.

The essential oils of forty natural populations of Pelargonium capitatum were steam distilled and analyzed by GC and GC/MS. The composition of the oil is extremely variable from one population to another, leading to the conclusion that there are several chemotypes in this species. The main constituents found were α-pinene, α-phellandrene, p-cymene, γ-terpinene, β-caryophyllene, guaia-6, 9-diene, germacrene D, δ-cadinene, citronellol, terpinen-4-ol, 10-epi-γ-eudesmol, citronellyl formate, and an unidentified sesquiterpene.

Dwarf plants derived from tissue cultures of Pelargonium capitatum, gave an essential oil of quite different composition from that produced by normal plants. This difference persisted for as long as the plant demonstrated the effect of the growth retardant. The chemical composition of the essential oil derived from ‘growth-retarded plants’ is presented.

WOS: 000239708300018, A plethora of information is available on the essential oil composition of commercially grown Pelargonimus namely P. capitatum, P. graveolens and P. radens and their hybrids, while only a few chemical investigations have been carried out on the other aromatic Pelargonium species indigenous to South Africa. The hydrodistilled leaf oils of 13 South African Pelargonium species of the genus Pelargonium (family Geraniaceae) were analyzed by means of GC and GC/MS and a total of 315 compounds were identified. The oil data was chemotaxonomically informative confirming taxonomic relationships i.e. between P. graveolens and P. radens, P papilionaceum and P. vitifolium and between P panduriforme and P quercifolium. The oil compositions of P citronellum, P papilionaceum and P vitifolium were different with respect to those of the other analyzed species in this study. Geranic acid was the most abundant oil constituent (36.0%) in P citronellum (provenance NBG), which was the only species in which neral (17.4%) and geranial (27.2%) were detected. Citronellic acid dominated in the oils of P. papilionaceum (provenance NBG) and P vitifolium (provenance SBG), occurring in amounts of 96.2% and 74.7%, respectively. The major monoterpene identified in P. radens (provenance NBG) and in the samples of P graveolens (provenances SBG and (WSBG) was isomenthone (84.5%, 65.8% and 83.3%, respectively). The P. tomentosum oil samples produced an essential oil rich in menthone (36.1-41.1%) and isomenthone (49.3-56.6%). The latter monoterpenic ketone,vas responsible for the chemical affinity demonstrated among P. graveolens, P. radens and P tomentosum. p-Cymene was the principle component (37.6-45.4%) in both samples of P panduriforme. It was also the major compound (54.9%) in P. quercifolium (provenance WSBG) followed by lesser amounts of viridiflorol (13.0%) and spathulenol (5.9%). Pelargonium quercifolium (provenance SBG) and P capitatum (provenance WSBG) were characterized by a high viridiflorol content (24.0-36.6%). Pelargonium glutinosum (provenance SBG) was closely associated with the latter species; its oil was typified by oxygenated sesquiterpenes namely caryophyllene oxide (6.3%), spathulenol (6.9%) and viridiflorol (8.9%). Citronellyl formate (31.1%), citronellol (9.9%) and furopelargone B (6.1%) were most abundant in P capitatum (provenance Strand). Pelargonium hispidum oil (provenance SBG) was characterized by decanoic acid (47.0%) and 2-decenoic acid (31.3%). Pelargonium scabrum produced an oil rich in 14-hydroxy-beta-caryophyllene (27.9%). Pelargonium scabrum was associated with P. betulinum (provenance NBG) which was characterized by the oxygenated sesquiterpene T-cadinol (18.9%).

The Pelargonium cultivar grown on Reunion for the production of rose-scented geranium oil is locally known as the cv. Rose. The origin of the cv. Rose is demonstrated by comparing its morphology, chromosome number and essential oil with those of putative ancestral species. It is concluded that P. capitatum (L.) L’Herit. and P. radens H.E. Moore can be considered as the parent species. A comparison of the characters of the cv. Rose and those of artificial hybrids between P. capitatum and P. radens , confirmed the assumption.

Pelargonium capitatum (L.) L’Herit. is one of the parent species oi the cultivar Rose grown on the Island of Reunion for its essential oil. The ultimate aim of this project is to identify chemotypes which could be included in hybridization programmes to ennoble the cultivar Rose. Forty populations of P. capitatum were selected along the west and east coasts of South Africa to describe the essential oil and macromorphological diversity in relation to geographical distribution. A multivariate statistical analysis was performed on the essential oil data. A survey of the composition of the volatile oils proved the species to display high levels of essential oil variation which allows for the species to be divided into chemotypes correlating to geographical distribulion. No clear-cut macromorphological discontinuities were apparent between populations, but an obvious congruence between the essential oil composition and macro-morphology was accentuated in extreme cases.