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Pelargonium capitatum (rose pelargonium) is a plant indigenous to southern Africa, originally brought to Western Australia for its ornamental qualities. It has since become naturalized in the Southwest Australian Floristic Region, recognized for its high level of species endemism, where it is a serious invasive weed in bushlands and coastal dunes. Since P. capitatum outcompetes native species it is listed among the top 10 most important coastal weeds of the region (3). In 2008, large patches of stunted, dying, and dead P. capitatum plants were observed within a population covering coastal dunes at Woodman Point, Western Australia (GPS coordinates 32°07′40.51″S, 115°45′28.39″E). Diseased plants had small misshapen leaves in clumps that were often chlorotic or pink, shortened internodes, and exhibited phylloidy typical of infection by a phytoplasma. From August 2009 to January 2010, samples from symptomatic and asymptomatic plants were collected from the site and from plants of an asymptomatic population at another site located on the Murdoch University campus nearby. DNA was extracted from 15 samples collected from symptomatic and asymptomatic plants at the dune site and from five at the campus site. Briefly, 2 to 5 g of leaf and stem tissue was cut into 5-mm pieces and shaken overnight in 30 ml of phosphate-buffered saline buffer. Supernatant was filtered and a pellet was collected by centrifugation. After resuspension in 500 μl of extraction buffer (200 mM Tris-HCl [pH 7.5] 250mM NaCl, 25mM ethylenediaminetetraacetic acid, 0.5% sodium dodecyl sulfate, and 2% polyvinylpyrrolidone), DNA was precipitated in 500 μl of cold isopropanol. Samples were tested for the presence of phytoplasma ribosomal 16S DNA by nested PCR using phytoplasma universal primers P1/P7 followed by amplification with primers Tint, R16mF2, and R16mR1 (1,2,4). Phytoplasma-specific DNA sequences were synthesized directly from amplicons using the above primers. Phytoplasma was detected from both symptomatic and asymptomatic plant samples collected from the dune site but not from the campus site. Analysis of the nine sequences obtained (GenBank Accession Nos. HM583339, HM583340, HM583341, HM583342, HM583343, HM583344, HM583345, HM583346, and HM583347) revealed high sequence identity between isolates (~99%) and with the ‘Candidatus Phytoplasma aurantifolia’ (16SrII) group of phytoplasmas (1,4). Presence of phytoplasma in symptomatic plants was confirmed by histological examination of stem sections stained with Dienes' stain. This finding is significant because there is potential for utilizing this phytoplasma to control P. capitatum where it has invaded ecologically significant sites, although its effect on indigenous plants must be determined first. Although phytoplasmas within the 16SrII group have been identified in Australia previously (1,4), to our knowledge, this is the first report of it infecting P. capitatum. References: (1) K. S. Gibb et al. Phytopathology 85:169, 1995. (2) D. E. Gundersen and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (3) B. M. J. Hussey et al. Western Weeds. A Guide to the Weeds of Western Australia. 2nd ed. Plant Protection Society of Western Australia, Victoria Park, 2007. (4) M. Saqib et al. J. R. Soc. West. Aust. 90:175, 2007.

Geranium, an important ornamental plant belong to the family Geraniaceae, is widely cultivated in urban landscapes and private gardens all over the world. During a survey in spring 2019, a few seed-propagated geranium plants exhibiting typical symptoms induced by phytoplasmas, including pale green and little leaves, phyllody, virescence, and witches’-broom symptoms, were observed in Jiroft, Kerman province of Iran. Total genomic DNA extracted from leaf midribs and petioles of the three symptomatic and two asymptomatic plants was used as a template in a nested polymerase chain reaction (PCR) assay using universal phytoplasma primer pairs P1/P7 followed by R16F2n/ R16R2 (Gundersen and Lee 1996) to amplify a part of the 16S rDNA phytoplasma genome as previously described by Azadvar et al. (2011). The generated 1.8- and 1.25-kb amplicons in the first and second round of the nested PCR assay, respectively, from each of the three symptomatic plant samples revealed phytoplasma infection of the plants. No amplicon was generated in PCR assays by using the DNA templates from symptomless plants. The purified PCR products were directly sequenced (Bioneer, South Korea) in both forward and reverse directions. The consensus sequences were analyzed by the iPhyClassifier tool (Zhao et al. 2009) and pDRAW32 software (AcaClone software, http://www.acaclone.com) for 16Sr group/subgroup phytoplasma identification. The 16S rDNA nucleotide sequences from the three diseased plants were identical (GenBank accession no. MT187639). iPhyClassifier analysis showed that the F2nR2 16S rRNA encoding gene sequence of the phytoplasma associated with geranium little leaf (GrLL) disease in Iran was identical (similarity coefficient 1.00) to those of the reference pattern of 16Sr group II subgroup D (GenBank accession no. Y10097) and had 98.7% similarity with the ‘Candidatus Phytoplasma aurantifolia’ reference strain (GenBank accession U15442). Virtual restriction fragment length polymorphism (in silico RFLP) analysis of the 16S rDNA F2nR2 sequence with the pDRAW32 program using AluI, BamHI, BfaI, BstUI, DraI, EcoRI, HaeIII, HhaI, HinfI, HpaI, HpaII, KpnI, MseI, RsaI, Sau3AI, SspI, and TaqI endonucleases further confirmed that the GrLL phytoplasma belong to subgroup II-D. The 16SrII-D subgroup phytoplasma has been previously reported in association with Calendula officinalis (Esmailzadeh Hosseini et al. 2016), Helianthus annuus (Salehi et al. (2015), and Petunia hybrida (Faghihi et al. 2014) ornamental plants in Iran. We also found many petunia (P. hybrida) plants showing little leaf, yellowing, phyllody, and witches’-broom symptoms next to the GrLL-infected plants, which hosted the same phytoplasma (GenBank accession no. MT187637). A 16SrII group-related phytoplasma has previously been reported associated with Pelargonium capitatum weed plant exhibiting severe stunting and necrosis in Australia (Lee et al. 2010). To our knowledge, this is the first report of a ‘Ca. P. aurantifolia’ 16SrII-D subgroup-related phytoplasma associated with geranium (Pelargonium hortorum) little leaf disease in the world.

Twenty-five essential oils extracted from different sources (Aniba rosaeodora wood, Cananga odorata flowers, Cannabis sativa inflorescences, Cymbopogon citratus leaves, Citrus limon leaves, Citrus nobilis leaves, Cupressus sempervirens leaves, Curcuma longa rhizomes, Hypericum perforatum leaves, Illicium verum fruits, Melaleuca alternifolia leaves, Mentha × piperita leaves, Mentha spicata leaves, Monarda fistulosa leaves, Ocimum micranthum leaves, Ocimum basilicum leaves, Ocotea quixos leaves, Pelargonium capitatum leaves (two samples), Pinus nigra leaves, Pogostemon cablin leaves, Syzygium aromaticum leaves, Thymus vulgaris leaves, Vetiveria zizanoides roots, Zingiber officinale rhizomes) were screened for their phytotoxic behavior against Solanum lycopersicum seeds and seedlings in order to assess their capacity to inhibit germination, damage germinated seeds and alter the normal development of plantlets. The oils were analyzed by means of GC and GC–MS and a relationship between some functional groups and the ability to affect the germination or the development of roots and hypocotiles was evidenced by means of multivariate data analysis. A. rosaeodora, C. citratus, I. verum, M. × piperita, M. fistulosa, O. micranthum, S. aromaticum and in particular both Pelargonium samples were the most effective in both pre- and post-emergence stages. Multivariate data analysis allowed the construction of a model according to which the higher content in monoterpene alcohols, aldehydes or phenylpropanoids can be used as a predictor of distinct phytotoxic activities.

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.

The effect of irrigation frequency on leaf physiomorphological processes of rose-scented geranium ( Pelargonium capitatum × P. radens cv. Rose) was investigated in a glasshouse study at the Hatfield Experimental Farm of the University of Pretoria, Pretoria, South Africa, from November 2005 to October 2006. Daily, and every 2nd, 3rd, 4th , and 5th day irrigation were applied as treatments. Leaf samples for electron-microscopic observations were taken one week prior to harvesting, whereafter all plants were re-watered. For each of the irrigation frequency treatments, 50% of the plants were then exposed to a one-week irrigation withholding period (brief stress treatment) prior to harvesting. During this period, physiological properties were recorded on a daily basis to identify or monitor change. Higher irrigation frequency and a brief water stress period increased essential oil yield. Lower irrigation frequency tended to increase the citronellol to geraniol (C:G) ratio to unacceptably high levels (C:G > 3). Upon re-watering, stomatal conductance (G s ) and transpiration rate (R t ) were significantly lower for the lower irrigation frequency treatments, compared to the higher irrigation frequency treatments, while no noticeable differences were observed in water potential (ψ w ) and relative water content (RWC). At the end of the one-week stress period, G s , R t , ψ w and RWC were lower for the plants that were more frequently irrigated compared to the less frequently irrigated treatments. Water stress reduced leaf size, and apparently increased trichome density, whereas the total number of trichomes per leaf remained more or less the same, indicating that total essential oil yield is mainly affected by leaf number (and not by leaf size or trichome number). Stomatal closure was the main water stress avoiding/adaptation mechanism. These results demonstrate that rose-scented geranium plants can make physiomorphological adaptations to save water. However, such a water saving strategy was counter-productive, since it resulted in lower essential oil yield and lower water-use efficiency.

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.

Because of the emergence of multi-drug resistance bacteria and fungi, alternatives to conventional antimicrobial therapy are needed. This study aims to evaluate in vitro the antimicrobial activity of: Mirtus communis, Coriandrum sativum, Pelargonium capitatum, Cuminum cyminum, Ocimum basilicum, Citrus aurantium amara, Cymbopogon. winterianus, Cymbopogon martini, Salvia sclarea, Melaleuca alternifolia and Mentha suaveolens essential oils on bacteria and fungi, in relation to their chemical composition. The potential interaction of M. alternifolia (TTO), C. sativum (CDO) and M. suaveolens (EOMS) essential oils when used in combination with gentamicin and fluconazole has been evaluated. The results obtained showed a synergic effect on some bacteria and fungi, with FICI values ≤5. The cytotoxicity of TTO, CDO and EOMS was investigated towards HeLa cells. Only EOMS did not result cytotoxic at the active concentrations on micro-organisms. Further studies are necessary to obtain optimal ratios and dosing regimens for higher therapeutic efficacy and to decrease toxicological profiles.

Increased nutrient availability can have a large impact in Australian woodland ecosystems, many of which are very poor in nutrients, particularly phosphorus. A study was conducted in an urban Banksia woodland remnant in Perth, southwest Western Australia to test the hypothesis that the soil nutrient status in areas in good condition (GC), poor condition invaded by the perennial grass Ehrharta calycina (PCe), and poor condition invaded by the perennial herb Pelargonium capitatum (PCp), is re- flected in the nutrient status of the native and intro- duced species. Leaf concentrations of P, K, N, Na, Ca, Mg, S, B, Cu, Fe, Mn and Zn of six native (Banksia attenuata, Banksia menziesii, Allocasuarina humilis, Melaleuca systena, Macrozamia fraseri and Conostylis aculeata) and four introduced species (Ehrharta calycina, Pelargonium capitatum, Gladi- olus caryophyllaceus and Briza maxima), were mea- sured. Soil pH, electrical conductivity, N (total), P (total), available P, K, S and organic C were assessed beneath all species on all sites. Significantly higher concentrations of soil P (total) and P (HCO3) were found at PCe and PCp sites than GC sites, while PCp sites also had significantly higher soil concentrations for N (total) and S. Principal Components Analysis of the leaf analyses showed (a) individual species have characteristically different nutrient concentrations; (b) the introduced species Ehrharta calycina and Pelargonium capitatum clustered separately from each other and by vegetation condition. Leaf con- centrations of P were significantly (P < 0.05) higher, and K and Cu were significantly lower in PCe and PCp sites compared with those at GC sites. Intro- duced species leaf nutrient concentrations were sig- nificantly greater than native species for all nutrients except Mn which was significantly lower, with no differences for Mg and B. The results indicate a key role for P in the Banksia woodland, and we conclude that higher levels of available P at invaded sites are having a detrimental impact on the ecosystem. These results provide new knowledge to enhance conser- vation practices for the management of the key threatening process of invasion within a biodiversity hot spot.

Seed dormancy was analysed in Geraniaceae, testing 29,103 seeds of 35 species for seed-coat impermeability to water. Seeds of wild and cultivated species from a number of different climatic/ecological zones (northern Germany, the Canary Islands and South Africa) were investigated. Seeds from cultivated plants and natural populations had similar (±2%) percentages of water-impermeable seeds. The percentages of impermeable seeds at maturity were also mostly constant (±2%) for two different years. The species analysed contained from 0 to 100% impermeable seeds at maturity, and could be classified into three quantitative types of physical dormancy: four species with no impermeable seeds (PY0), 10 species with a maximum of 80% impermeable seeds (PY80), and 21 species with more than 80% impermeable seeds (PY100). Species with different life cycles and from very different habitats, e.g. Geranium pratense or Pelargonium capitatum, belonged to the PY100 group. However, all of the succulent shrubs investigated from the genus Pelargonium were PY0 species. Five years of dry storage at 20 ± 5°C decreased physical dormancy in a species-dependent fashion. Erodium cicutarium, for example, had 95% impermeable seeds at maturity; all of them became permeable during the dry storage and began to germinate immediately after placing them on a moist substrate. Physical dormancy of other species, e.g. Pelargonium zonale, Pelargonium vitifolium or Geranium pratense, was not affected by dry storage. Thus, physical dormancy is a diversely differentiated feature in Geraniaceae with regard to both percentages of impermeable seeds at maturity and maintenance of dormancy under particular conditions.

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.

International audience; Shoot organogenesis from mature leaf tissues of two scented Pelargonium capitatum cultivars, 'Attar of Roses' and 'Atomic Snowflake', grown in the greenhouse, were optimized in the presence of thidiazuron (TDZ). The protocol involved preculture of leaf sections on basal Murashige and Skoog (MS) medium supplemented with 10 lM TDZ, 4.4 lM of 6-benzyladenine (BA) and 5.4 lM a-naphtaleneacetic acid (NAA) for a period of 2 weeks and followed by subculture of explants to a fresh medium containing 4.4 lM BA and 5.4 lM NAA. Frequency of regeneration reached approximately 93% for both cultivars, with the induction of more than 100 shoots per explant. Regenerated plantlets were rooted on half-strength MS medium supplemented with 4.4 mM sucrose and 8.6 lM of Indole-3-acetic acid (IAA). All regenerated shoots from both cultivars developed roots when transferred to organic soil mix, acclimatized, and successfully transferred to greenhouse conditions. When regenerated shoots were transferred to hydroponic conditions, frequency of survival was 76.2 and 61.9% for 'Attar of Roses' and 'Atomic Snowflake', respectively.

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.

Geranium capitatum Linnaeus, Species Plantarum 2: 678. 1753. "Habitat in Africa." RCN: 4947. Lectotype (van der Walt in Bothalia 15: 353. 1985): Herb. Linn. No. 858.17 (LINN). Current name: Pelargonium capitatum (L.) L���H��r. (Geraniaceae)., Published as part of Jarvis, Charlie, 2007, Chapter 7: Linnaean Plant Names and their Types (part G), pp. 529-556 in Order out of Chaos. Linnaean Plant Types and their Types, London :Linnaean Society of London in association with the Natural History Museum on page 529, DOI: 10.5281/zenodo.291971

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%).

Summary Pruning, defoliation and transplanting experiments were carried out ona woody hybrid of Pelargonium in order to assess the importance of correlative inhibition. Compensatory growth following pruning appears to be an essentially global property of the plant: no direct correlation was found between neighbouring shoots. Nevertheless strong physiological integration exists in the apical part of the shoot where reaction to pinching or defoliation will develop. Basal shoots of a plant, whose early development takes place in a stressed environment, show a substantial underdevelopment once replaced in favourable conditions. Since competition or correlative inhibition can hardly be invoked here it is concluded that some memory of the suffered stress is kept at the level of the apex. A possible nature of this imprint is put forward.

L'analyse qualitative des huiles essentielles extraites de populations de Pelargonium capitatum (L.) L'herit. d'Afrique du Sud a permis de distinguer des groupes et sous-groupes de plantes conduisant à supposer que la region du Cap Est le centre de différenciation de cette espèce. Des travaux sont également menés à la Réunion pour créer des hybrides de Pelargonium vitifolium bons producteurs et dont les huiles sont riches en citronellol. Une étude technique a été enfin réalisée sur les évolutions possibles des systèmes de distillation traditionnels à la Réunion et des essais de culture de geranium en basse altitude ont été entrepris pour dégager les bases d'un référentiel technique dans ces conditions encore atypiques

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.

A l'île de la Réunion, la culture des pélargoniums de parfumerie ("géranium rosat") est confrontée à des problèmes phytopathologiques dont la solution actuelle passe nécessairement par la génétique. La stérilité mâle de tous les cultivars, et la méconnaissance de la filiation des ces plantes dans le genre Pelargonium (Geraniaceae), ont jusqu'ici constituté des obstacles rédhibitoires à toutes les tentatives d'amélioration variétale. Les études originales présentées sur la composition des huiles essentielles des espèces sauvages conduisent à proposer un schéma de biosynthèse des molécules monoterpéniques dans les essences des Pelargonium à feuilles odorantes. Ces critères biochimiques s'avèrent un excellent outil en taxonomie, en systématique et dans la prévision de la transmission des caractères des essences chez les hybrides interspécifiques. L'hybridation interspécifique à partir d'espèces sauvages permet la création d'hybrides intéressants tant pour la qualité de leur production d'essence que pour leur résistance à certaines maladies. Des stratégies de sélection sont proposées en ce sens, et ont, pour certaines, été vérifiées