Growth, water use, yield and quality parameters in oregano affected by reduced irrigation regimes.

BACKGROUND: Determining plant tolerance to water stress is necessary in irrigation scheduling, decisions concerning supplementary irrigation, planning and operation and, more importantly, the rational use of water resources. In the present study, effects of the irrigation regime on oregano growth, water use, yield and quality parameters were investigated using reduced irrigation regime treatments. RESULTS: Increased water stresses caused a decrease in all growth and yield parameters. Plant water use efficiency was not significantly different among the control, low and medium stress treatments, although it was the lowest for the extreme water stress treatment. Total essential oil yield was the only quality parameter demonstrating significant differences among treatments. Yield response factors were determined as 1.13, 1.12, 1.06 and 1.10 for total fresh, total dry, dry leaf and total essential oil yields, respectively. CONCLUSION: Yield response factors indicate that oregano plant is slightly sensitive to water stress. Although the yield parameters were affected by water stress, Origanum onites, under cultivation in recent years, might have developed a resistance mechanism for quality parameters because it has grown in very dry conditions under a natural environment for many years. However, the negative relationships between crop evapotranspiration versus essential oil, total phenolic and flavonoid contents and extract yield indicates that the quality parameters of oregano under low plant water consumption may be increased. © 2020 Society of Chemical Industry.

Growth effects in oregano plants (Origanum vulgare L.) assessment through inoculation of bacteria isolated from crop fields located on desert soils.

Bacteria can establish beneficial interactions with plants by acting as growth promoters and enhancing stress tolerance during plant interactions. Likewise, bacteria can develop multispecies communities where multiple interactions are possible. In this work, we assessed the physiological effects of three bacteria isolated from an arid environment (Bacillus niacini, Bacillus megaterium, and Moraxella osloensis) applied as single species or as a consortium on oregano (Origanum vulgare L.) plants. Moreover, we assessed the quorum-sensing (QS) signaling activity to determine the molecular communication between plant-growth-promoting bacteria. The plant inoculation with B. megaterium showed a positive effect on morphometric and physiologic parameters. However, no synergistic effects were observed when a bacterial consortium was inoculated. Likewise, activation of QS signaling in biofilm assays was observed only for interspecies interaction within the Bacillus genus, not for either interaction with M. osloensis. These results suggest a neutral or antagonistic interaction for interspecific bacterial biofilm establishment, as well as for the interaction with oregano plants when bacteria were inoculated in a consortium. In conclusion, we were able to determine that the bacterial interactions are not always positive or synergistic, but they also might be neutral or antagonistic.

Chemical Compositions and Anti-Skin-Ageing Activities of Origanum vulgare L. Essential Oil from Tropical and Mediterranean Region.

Origanum vulgare L. has been used as a culinary ingredient worldwide. This study revealed the cosmeceutical potential of O. vulgare essential oil as a skin-ageing retardant. The O. vulgare essential oil from a highland area of a tropical country (HO), obtained by hydrodistillation was investigated and compared to a commercial oil from the Mediterranean region (CO). Their chemical compositions were investigated by gas chromatography-mass spectrometry. Antioxidant activities were investigated by ferric reducing antioxidant power, 1,1-diphenyl-2-picrylhydrazyl, and ferric thiocyanate assay. Anti-skin-ageing activities were determined by means of collagenase, elastase, and hyaluronidase inhibition. Carvacrol was the major component in both oils, but a higher amount was detected in HO (79.5%) than CO (64.6%). HO possessed comparable radical scavenging activity to CO (IC50 = 1.8 ± 0.8 mg/mL) but significantly higher lipid peroxidation inhibition (38.0 ± 0.8%). Carvacrol was remarked as the major compound responsible for the reducing power of both oils. Interestingly, HO possessed significant superior anti-skin-ageing activity than ascorbic acid (P < 0.01), with inhibition against collagenase, elastase, and hyaluronidase of 92.0 ± 9.7%, 53.1 ± 13.3%, and 16.7 ± 0.3%, at the concentration of 67, 25, and 4 µg/mL, respectively. Since HO possessed comparable anti-hyaluronidase activity to CO and superior anti-collagenase and anti-elastase (P < 0.01), HO was suggested to be used as a natural skin-ageing retardant in a cosmetic industry.

Fundamental Study on the Salt Tolerance of Oregano Essential Oil-in-Water Nanoemulsions Containing Tween 80.

This study provides fundamental information about the influence of salt on the physicochemical stability of oregano essential oil (EO) and its main components incorporated in a nanoemulsion delivery system containing Tween 80 (T80) emulsifier. The emulsion stability was found to be strongly correlated with the lipid phase composition and the type of salts. The oregano essential oil nanoemulsions remained stable for several weeks in the absence of salts. Moreover, they were insensitive to tetrabutylammonium bromide, whereas similar to carvacrol emulsions, they exhibited a rapid phase separation and oiling-off in the presence of sodium chloride. On the other hand, high oleic sunflower oil (HOSO) and p-cymene emulsions remained stable in the presence of NaCl. Addition of 70 and 80% HOSO to the lipid phase of oregano EO and carvacrol, respectively, was found to be sufficient for the formation of emulsions with a high stability to 1.7 M NaCl. Hereby, the morphology of the oregano EO emulsions after 30 days of storage in the presence of NaCl was visualized using a transmission electron microscope. The determination of the surface load and area per surfactant molecule by interfacial tension (IFT) measurements and quartz crystal microbalance with dissipation revealed the dehydration of the polyoxyethylene groups of T80 in the presence of salt. The thickness of the T80 adsorbed layer onto solid hydrophobic and hydrophilic surfaces was significantly lower (p < 0.05) in the presence of sodium chloride. It is hypothesized that a combination of Ostwald ripening and coalescence due to an IFT increase and dehydration was responsible for the instability of the emulsions containing the more polar oregano EO and carvacrol in the presence of salt. The results obtained in this study could be useful for the formulation of essential oil nanoemulsions in the presence of salts applicable in food, pharmaceutical, and personal care products.

Determination of phenolic compounds by MALDI-TOF and essential oil composition by GC-MS during three development stages of Origanum majorana L.

This study aimed to investigate the effect of the maturation process of sweet marjoram (Origanum majorana L.) on essential oil composition, the phenolic profile of ethanolic extract and their antioxidant capacities. The essential oil composition was studied at three stages of maturity by GC-MS. Thirty compounds were detected representing 100% of the total essential oil. p-Menth-1-en-4-ol was the major compound (37.15-76.94%) followed by cyclohexanol-3,3,5 trimethyl (5.41-15.99%) and α-terpineol (0.94-11.34%). During the maturation process, an accumulation of oxygenated monoterpenes was observed. The phenolic composition was studied using matrix-assisted laser desorption/ionization time of flight. The analysis showed the presence of short flavonoid monomers at all stages of maturation. The antioxidant capacity of ethanolic extracts and essential oils was evaluated using the DPPH assay, iron chelating power and reducing power assay. The highest phenolic content and antioxidant capacity were found at flowering stage. These findings on essential oil composition, phenolic profile and antioxidant capacity of O. majorana at three different stages of development provide more information on how these secondary metabolites are accumulated.

Date of harvesting affects yields and quality of Origanum vulgare ssp. hirtum (Link) Ietswaart.

BACKGROUND: The aim of this experiment was to determine the essential oil, flavonoid and phenolic acid contents as well as yields of raw material collected from different morphological parts of Greek oregano in five consecutive developmental stages. Antibacterial and antifungal properties of methanol and hexane extracts from the aerial parts of Greek oregano were assessed as well. RESULTS: The findings showed that Greek oregano grown in the cool climate of central Europe had a considerable variation in the essential oil yield and chemical composition related to the harvesting stage. Forty volatile compounds were detected in essential oils, with the highest amount of carvacrol, thymol, p-cymene and γ-terpinene, constituting in total from 90.72 to 92.9%. CONCLUSION: Different morphological parts of the plants contained different amounts of essential oils, with dominant amounts in the flowers. The essential oil content systematically increased, reaching its maximum in the full blooming period. In that phase, the plants produced the highest yields of aboveground parts and provided approximately 190 L ha-1 of essential oils. Mainly owing to its content of phenolic compounds, the Greek oregano raw material exhibited relatively high antioxidant activity. The data obtained clearly showed the inhibitory activity of methanol and hexane extracts against pathogenic bacteria and fungi. © 2019 Society of Chemical Industry.

Influence of Environmental Factors on Essential Oil Variability in Origanum compactum Benth. Growing Wild in Morocco.

The present study aimed to evaluate the influence of environmental factors on essential oils (EOs) composition of Origanum compactum populations sampled all over the distribution area of the species in Morocco, and to determine the extent of the chemical profiles throughout the geographical distribution of the species. The chemical compositions were submitted to canonical correlation analysis and canonical discriminant analysis that indicated a significant relationship between oil components and some environmental factors. According to their chemical composition and edapho-climatic characteristics, two major groups of populations were differentiated. The first group was composed of samples growing in regions with humid climate, clayey, sandy, and alkaline soils. These samples showed high thymol, α-terpineol, linalool, and carvacryl methyl oxide content. The second group consisted of plants belonging to semi-arid climate, and growing at high altitudes and silty soils. These samples were characterized by high carvacrol, α-thujene, α-terpinene, and myrcene content. However, populations exposed to sub-humid climate, appeared less homogeneous and belong mainly either to the first or second group. A significant correlation between some edaphic factors (pH, K2 O content, soil texture) and the EOs yield of O. compactum plants was evidenced. In spite of the correlation obtained for the oil composition with edapho-climatic factors and the variance explained by the environmental data set, the observed EO diversity might be also genetically determined.

Effect of prolonged water stress on essential oil content, compositions and gene expression patterns of mono- and sesquiterpene synthesis in two oregano (Origanum vulgare L.) subspecies.

Origanum vulgare L., recognized throughout the world as a popular medicinal and flavoring herb, contains a wide array of medicinally active components, including phenolic glucosides, flavonoids, tannins, sterols and high amounts of terpenoids. Especially the latter are often extracted by hydrodistillation resulting in the so-called essential oil that is rich in monoterpenes (e.g. carvacrol, thymol, linalyl acetate) and/or sesquiterpenes (e.g. (E)-ß-caryophyllene, germacrene D, bicyclogermacrene, ß-caryophyllene oxide). Water stresses in the arid and semiarid regions of the world severely affect growth and productivity of oregano. To determine the variation in essential oil and gene expression pathway of Iranian oregano under prolonged water stress, two native subspecies of O. vulgare (subsp. virens and subsp. gracile) were studied. The plants, grown in pots, were subjected to three water stress conditions, i.e. no stress, mild stress (60± 5% FMC) and moderate stress (40± 5% FMC). The studied subspecies exhibited significant differences in essential oil content, compositions, and patterns of gene expression under water stress conditions. The essential oil of O. vulgare subsp. gracile was rich in the phenolic monoterpene carvacrol (46.86-52.07%), whereas the sesquiterpene hydrocarbon (Z)-α-bisabolene (39.17-42.64%) was the major constituent in the oil of O. vulgare subsp. virens. Both the mild and moderate water stresses significantly increased the essential oil content of O. vulgare subsp. gracile, but did not significantly change the essential oil content of O. vulgare subsp. virens nor the level of carvacrol and (Z)-α-bisabolene in the investigated subspecies. Interestingly, the amount of (E)-ß-caryophyllene in O. vulgare subsp. virens was significantly increased under water stress conditions. Gene expression studies supported the above findings and demonstrated that there are two different pathways affecting the biosynthesis of the terpenoid precursors geranyl pyrophosphate (GPP) and farnesyl pyrophosphate (FPP). In O. vulgare subsp. gracile, HMGR, Ovtps2 and CYP71D180 transcript were up-regulated under mild and moderate water stress conditions. Transcription of FPPS was apparently down-regulated in water-stressed O. vulgare subsp. gracile. Investigation of terpene synthases expression levels in oregano subspecies demonstrated that Ovtps2 and Ovtps6 controlled the concentration of carvacrol and (E)-ß-caryophyllene in oregano essential oils, respectively.

Effects of irrigation intervals and organic manure on morphological traits, essential oil content and yield of oregano ( Origanum vulgare L.).

In order to evaluate the effect of irrigation intervals and cattle manure levels on morphological traits, essential oil content and yield of oregano, an experiment was conducted at the experimental Farm of the Faculty of Agriculture, Urmia University, Iran. The experimental design was split-plots, arranged in randomized complete blocks with three replications. Main plots including irrigation intervals (1, 2 and 3 weeks) and four levels of cattle manure at 0, 10, 20 and 30 t ha-1 were allocated to sub plots. Our results showed that increasing irrigation intervals reduced values of all morphological traits except for proportion of stems. Also, values for stems number, plant spread, stem diameter, leaf area, fresh and dry herb yield increased by increasing cattle manure levels. On the other hand, morphological traits not influenced by interaction of treatments except for plant spread and leaf area. The highest essential oil content (2.07%) and yield (66.62 kg ha-1) obtained in highest irrigation intervals and cattle manure levels. Whereas, 1 week irrigation interval without use of cattle manure produce lowest essential oil content (1.55%). For essential oil yield, the lowest value (46.37 kg ha-1) was found in 2 weeks irrigation interval with application of 20 t ha-1 cattle manure.

Effects of Plant Density on the Number of Glandular Trichomes and on Yield and Quality of Essential Oils from Oregano.

Plants yields are influenced by agronomic techniques. Plant density is a complex issue and extremely important when maximizing both crop quality, and biomass and essential oil yields. Plants belonging to the Origanum vulgare subspecies hirtum (Link) Ietswaart were grown adopting four types of plant density and were characterized in biometric and chemical terms. The samples were analyzed using the ANOVA (Principal Component Analysis) statistical method regarding biometric aspects, EO yield and peltate hair density. Essential oil (EO) was extracted by hydrodistillation and analyzed using GC-FID and GC-MS. GC-FID and GC-MS analysis led to the identification of 45 compounds from the EO. Plant density affected production both in terms of biomass and EO. However, it was not found to have affected peltate glandular trichome density or EO quality.

Chemical Polymorphism of Origanum compactum Grown in All Natural Habitats in Morocco.

Origanum compactum L. (Lamiaceae) is one of the most important medicinal species in term of ethnobotany in Morocco. It is considered as a very threatened species as it is heavily exploited. Its domestication remains the most efficient way to safeguard it for future generations. For this purpose, wide evaluation of the existing variability in all over the Moroccan territory is required. The essential oils of 527 individual plants belonging to 88 populations collected from the whole distribution area of the species in Morocco were analyzed by GC/MS. The dominant constituents were carvacrol (0 - 96.3%), thymol (0 - 80.7%), p-cymene (0.2 - 58.6%), γ-terpinene (0 - 35.2%), carvacryl methyl ether (0 - 36.2%), and α-terpineol (0 - 25.8%). While in the Middle Atlas region and the Central Morocco mainly carvacrol type samples were found, much higher chemotypic diversity was encountered within samples from the north part of Morocco (occidental and central Rif regions). The high chemical polymorphism of plants offers a wide range for selection of valuable chemotypes, as a part of breeding and domestication programs of this threatened species.

Chemical Composition and Antimicrobial Activity of Origanum libanoticum, Origanum ehrenbergii, and Origanum syriacum Growing Wild in Lebanon.

The essential oils (EOs) of the aerial parts of Origanum libanoticum and Origanum ehrenbergii, endemic to Lebanon, and Origanum syriacum, endemic to the Levantine, were obtained by distillation with a Clevenger apparatus. GC and GC/MS allowed identification of 96.4%, 93.5%, and 95.2% of their constituents, respectively. Carvacrol was the major component of both O. syriacum EO (79%) and O. ehrenbergii EO (60.8%). This compound was absent in O. libanoticum EO and the major compounds were ß-caryophyllene (26.8%), caryophyllene oxide (22.6%), and germacrene D (17.2%). The assessment of their antimicrobial activity against Candida albicans and six pathogenic bacteria revealed that O. libanoticum EO was inactive, while O. syriacum and O. ehrenbergii showed moderate antimicrobial activity with minimal inhibitory concentrations varying from 400 to 1200 µg/ml. These results support the traditional use of these last two species in traditional herbal preparations in Lebanon.

Effect of Arbuscular Mycorrhizal Fungi on the Growth and Polyphenol Profile of Marjoram, Lemon Balm, and Marigold.

The aim of this study is to examine the effect of arbuscular mycorrhizal fungi (AMF) colonization on biomass, polyphenol profile, and content of economically important herbs. A pot experiment was performed with marjoram, lemon balm, and marigold applying a commercially available AMF mixture for inoculation. Major polyphenols were identified using HPLC-UV-ESI-qTOFMS on the basis of their UV-vis and mass spectral characteristics, and selected ones were quantified. We showed that AMF can provide different services for each herb. Marjoram had the highest level of fungal colonization (82 M%) followed by lemon balm (62 M%) and marigold (17 M%). AMF inoculation significantly increased the biomass of marjoram (1.5-fold), the number of marigold flowers (1.2-fold), and the yield of rosmarinic acid and lithospermic acid isomers of marjoram (1.5-fold) and lemon balm (1.2-fold). Therefore, the quantity and quality of plant material could be improved by the application of optimized AMF inoculum.

EFFECT OF HARVEST DATE AND STALK SECTION ON SELECTED STRENGTH CHARACTERISTICS OF TURKISH OREGANO (Origanum onites L).

BACKGROUND: The time required to harvest plant crops is important to the plant properties. It is affected by design of the harvest equipment and the desire for high-quality products with low energy usage. MATERIALS AND METHODS: Strength characteristics of Origanum onites L., an important medicinal aromatic plant, harvested on 2, 9, 16 and 23 July, 2012-2014 (H1, H2, H3 and H4, respectively) were measured at the bottom and top sections of the stalk. Measurements included maximum force, bio-yield force, shearing force, bending stress, shearing stress, shearing energy, and shearing deformation. RESULTS: The highest maximum force (35.17 N) was at H4 on the bottom section, and the lowest was at H1 on the top. Maximum values for bio-yield force, shearing force, and bending stress were at H4 on the bottom section, and corresponding minimum values were at H1 on the top section. Shearing stress decreased at successive harvest dates for both stalk sections. The minimum shearing energy was at H4, (0.13 J and 0.06 J for bottom and top, respectively). Strength measurements for bottom sections of the stalk were greater than those for top sections. CONCLUSION: When reduced harvesting force is needed because of harvester design or harvest procedures, harvesting near the top of the stalk is recommended.

Chemical content, antibacterial and antioxidant properties of essential oil extract from Tunisian Origanum majorana L. cultivated under saline condition.

Essential oils of marjoram were extracted from plants, growing under non-saline and saline condition (75mM NaCl). Their antioxidant and antibaterial activity against six bacteria (Enterococcus faecalis, Escherichia coli, Salmonella enteritidis, Listeria ivanovii, Listeria inocula, and Listeria monocytogenes) were assessed. Result showed that, (i) independently of salt treatment, marjoram essential oils inhibited the growth of most of the bacteria but in degrees. The least susceptible one was Enterococcus faecalis. (ii) Gram negative bacteria seemed more sensitive to treated essential oils than Gram positive ones. (iii) Compared to synthetic antibiotics, marjoram essential oils were more effective against E. coli, L. innocua and S. enteridis. This activity was due to their high antioxidant activity. Thus, essential oils of marjoram may be an alternative source of natural antibacterial and antioxidant agents.

Phytochemical screening, anticancer and antioxidant activities of Origanum vulgare L. ssp. viride (Boiss.) Hayek, a plant of traditional usage.

BACKGROUND: A detailed phytochemical analysis of Origanum vulgare L. ssp. viride (Boiss.) Hayek was carried out and the antioxidant activities of five different crude extracts were determined. The antiproliferative activities of the extracts were determined using the xCELLigence system (Real Time Cell Analyzer). RESULTS: Differences between the essential oil and volatile organic compound profiles of the plant were shown. The main component of the essential oil was caryophyllene oxide, while the main volatile organic compounds were sabinene and eucalyptol as determined by HS-GC/MS. Phenolic contents of the extracts were determined qualitatively and quantitatively by HPLC/TOF-MS. Ten phenolic compounds were found in the extracts from O. vulgare and Origanum acutidens: rosmarinic acid (in highest abundance), chicoric acid, caffeic acid, p-coumaric acid, gallic acid, quercetin, apigenin-7-glucoside, kaempferol, naringenin and 4-hydroxybenzaldehyde. CONCLUSION: This study provides first results on the antiproliferative and antioxidant properties and detailed phytochemical screening of O. vulgare ssp. viride (Boiss.) Hayek.

Differentiating organically and conventionally grown oregano using ultraperformance liquid chromatography mass spectrometry (UPLC-MS), headspace gas chromatography with flame ionization detection (headspace-GC-FID), and flow injection mass spectrum (FIMS) fingerprints combined with multivariate data analysis.

Ultraperformance liquid chromatography mass spectrometry (UPLC-MS), flow injection mass spectrometry (FIMS), and headspace gas chromatography (headspace-GC) combined with multivariate data analysis techniques were examined and compared in differentiating organically grown oregano from that grown conventionally. It is the first time that headspace-GC fingerprinting technology is reported in differentiating organically and conventionally grown spice samples. The results also indicated that UPLC-MS, FIMS, and headspace-GC-FID fingerprints with OPLS-DA were able to effectively distinguish oreganos under different growing conditions, whereas with PCA, only FIMS fingerprint could differentiate the organically and conventionally grown oregano samples. UPLC fingerprinting provided detailed information about the chemical composition of oregano with a longer analysis time, whereas FIMS finished a sample analysis within 1 min. On the other hand, headspace GC-FID fingerprinting required no sample pretreatment, suggesting its potential as a high-throughput method in distinguishing organically and conventionally grown oregano samples. In addition, chemical components in oregano were identified by their molecular weight using QTOF-MS and headspace-GC-MS.

Prediction of essential oil content of oregano by hand-held and Fourier transform NIR spectroscopy.

BACKGROUND: In the framework of a breeding programme, the analysis of hundreds of oregano samples to determine their essential oil content (EOC) is time-consuming and expensive in terms of labour. Therefore developing a new method that is rapid, accurate and less expensive to use would be an asset to breeders. The aim of the present study was to develop a method based on near-inrared (NIR) spectroscopy to determine the EOC of oregano dried powder. Two spectroscopic approaches were compared, the first using a hand-held NIR device and the second a Fourier transform (FT) NIR spectrometer. RESULTS: Hand-held NIR (1000-1800 nm) measurements and partial least squares regression allowed the determination of EOC with R² and SEP values of 0.58 and 0.81 mL per 100 g dry matter (DM) respectively. Measurements with FT-NIR (1000-2500 nm) allowed the determination of EOC with R² and SEP values of 0.91 and 0.68 mL per 100 g DM respectively. RPD, RER and RPIQ values for the model implemented with FT-NIR data were satisfactory for screening application, while those obtained with hand-held NIR data were below the level required to consider the model as enough accurate for screening application. CONCLUSION: The FT-NIR approach allowed the development of an accurate model for EOC prediction. Although the hand-held NIR approach is promising, it needs additional development before it can be used in practice.

Crescimento de mudas de orégano submetidas a doses e frequências de aplicação de Ácido L-glutâmico em sistema orgânico / Growth of oregano (Origanum vulgare L. ) seedlings in different levels and frequencies of foliar application of the l-glutamic acid in the organic system

O presente trabalho teve por objetivo identificar o efeito de diferentes doses e frequências de aplicação do biofertilizante aminoácido Ácido L-glutâmico em mudas de orégano produzidas em sistema orgânico, quantificando seu crescimento. Os tratamentos compostos por 2 doses (0,4 e 0,8 mL L-1) de Ácido L-glutâmico a 30%, e testemunha com água, foram aplicados via foliar em intervalos regulares de 7 e 14 dias, por 28 dias (fatorial 3 x 2, com 4 e 2 aplicações, respectivamente), em delineamento inteiramente casualizado com 4 repetições. Aos 62 dias após a semeadura foi realizada a coleta de 8 plantas centrais por repetição para avaliação de características biométricas da parte aérea e das raízes. O experimento demonstrou que o biofertilizante aminoácido ácido L-glutâmico influenciou as características avaliadas. A dose de 0,8 mL L-1, aplicada com intervalo de 14 dias, promoveu maior crescimento das mudas de orégano.

The aim of this study was to identify the effect of the different levelsand frequencies of foliar application of the biofertilizer L-glutamic acid in oregano seedlings produced in the organic system, quantifying their growth. The treatments were arranged in a completely randomized design with four replications in a 3 x 2 factorialarrangement, consisting of two doses (0.4 and 0.8 ml L-1) of a compound with 30% L -glutamic acid and a control, under a frequency of two applications, with a total of 4 applications for the 7-day frequency, and 2 applications for the 14-day frequency. At the 62nd day after sowing, eight plants were collected per replication for measuring biometric characteristics of shoots and roots. The biofertilizer L-glutamic acid affected the evaluated characteristics, and the dose of 0.8 ml L-1 (applied with a 14-day interval), promoted greater seedling growth of oregano.

Chemical composition and biological activity of essential oils of Origanum vulgare L. subsp. vulgare L. under different growth conditions.

This research was aimed at investigating the essential oil production, chemical composition and biological activity of a crop of pink flowered oregano (Origanum vulgare L. subsp. vulgare L.) under different spatial distribution of the plants (single and binate rows). This plant factor was shown to affect its growth, soil covering, fresh biomass, essential oil amount and composition. In particular, the essential oil percentage was higher for the binate row treatment at the full bloom. The chemical composition of the oils obtained by hydrodistillation was fully characterized by GC and GC-MS. The oil from plants grown in single rows was rich in sabinene, while plants grown in double rows were richer in ocimenes. The essential oils showed antimicrobial action, mainly against Gram-positive pathogens and particularly Bacillus cereus and B. subtilis.