Essential Oil Content Research Articles

Transcriptome analysis reveals regulatory mechanism of methyl jasmonate-induced monoterpenoid biosynthesis in Mentha arvensis L.

Mentha arvensis L. (M. arvensis) is an aromatic plant of the Mentha genus, renowned for its medicinal and economic importance. The primary components of its essential oils (EOs) are monoterpenoids, synthesized and stored in peltate glandular trichomes (PGTs). In general, the EO content in M. arvensis is relatively low. Methyl jasmonate (MJ) has been reported as an effective elicitor of terpenoid biosynthesis in medicinal plants, but the specific mechanisms underlying MJ’s influence on M. arvensis remain unclear. In this study, exogenous application of MJ significantly increased the EO content, yield, and PGT density in a dose-dependent manner. At a 5 mM dose, the EO content and PGT density peaked, with increases of 71.20% and 53.69%, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis indicated that, in general, MJ treatment did not significantly alter the types or relative proportions of EO components of M. arvensis. However, L-menthol content decreased slightly by 7.90% under 5 mM MJ treatment. Transcriptome analysis identified 4,659 differentially expressed genes (DEGs) in MJ-treated leaves. KEGG enrichment analysis revealed that “Monoterpenoid biosynthesis” was among the most significantly enriched metabolic pathways. Key genes involved in jasmonic acid (JA) signaling (JAZs and MYCs) and monoterpenoid biosynthesis (GPPSs, LSs, L3Hs, and IPRs) were significantly up-regulated. Co-expression analysis, promoter binding element analysis and weighted gene co-expression network analysis (WGCNA) indicated that transcription factors (TFs) such as AP2/ERF, WRKY, MYB, and bHLH play crucial roles in regulating MJ-mediated monoterpenoid biosynthesis. Several key candidate TFs potentially involved in regulating monoterpenoid biosynthesis in M. arvensis were identified. These findings provide valuable insights into the molecular mechanisms regulating monoterpenoid accumulation in the Mentha genus.

Essential oil and phenolic compounds in different organs and developmental stages of Monarda didyma L., and their biological activity.

Plant development has a greater impact on the chemical composition of inflorescences than of the leaves and stems of Monarda didyma plants. Monarda didyma L. is a well-known ornamental and aromatic plant. However, no studies are yet available concerning the diversity in the chemical composition of M. didyma organs during plant development that affect the final quality of the raw material. This study aimed to determine the content of phenolic compounds, essential oil (EO), and their composition in various organs affected by plant development. Furthermore, the antimicrobial activity of leaf and inflorescence EOs and the antioxidant activity of leaves, stems, and inflorescences were determined. EO content in the leaves and inflorescences collected during flowering was 2.39% and 3.64%, respectively. The main ingredients of the investigated EOs were p-cymene (17.11-35.56%) and carvacrol (5.39-28.19%). The EOs from the leaves and inflorescences collected during flowering inhibited the growth of six investigated microbial strains at the concentration range 0.313-1.250 µL × mL-1. Total phenolic and flavonoid content in leaves was higher than in inflorescences and stems. The leaves were found to be rich in didymin (average content 1283.63mg × 100g-1), while the inflorescences collected during flowering contained a significant amount of linarin (1247.47mg × 100g-1). The variability in the content and composition of EO and phenolic compounds depending on the stage of plant development was mainly observed in inflorescences. These findings contribute to better understanding of distribution and accumulation of biologically active compounds in M. didyma aerial organs, the potential of these organs as raw materials for medicinal, cosmetic and food applications, and the importance of the time of their harvesting.

Development of Alginate-Chitosan Bioactive Films Containing Essential Oils for Use in Food Packaging

The effect on the physical, mechanical, and antibacterial properties of films composed of alginate-chitosan with the incorporation of oregano (EOO) or thyme (EOT) essential oils was evaluated. These films showed a thickness between 37.7 and 38.2 µm, with no significant differences for essential oil content. Water vapor permeability decreased from 4.03 (oil-free film) to 1.65 (g/msPa) × 10−9 in 3% EO. Mechanical properties reflected a reduction in tensile strength (TS) from 73 (oil-free films) to values between 34 and 38 MPa with 3% EO, while elongation (E%) increased from 4.8% to 10.4–11.8%. Regarding antibacterial capacity, as the concentration of essential oil increases, the antibacterial capacity also increases. On average, the increase from 1.0% to 3.0% of EOO increased the antimicrobial capacity against Gram-negative and Gram-positive bacteria. EOO outperformed EOT against E. coli and L. monocytogenes. In addition, films with 2–3% EOT showed a significant dark yellow color compared to the control. These results suggest that films with the addition of oregano and thyme essential oils can be promising for food packaging applications with the ability to improve food safety and increase product shelf life by achieving functional packaging characteristics.

The Potency of Essential Oils in Combating Stored-Product Pests: From Nature to Nemesis

Sitophilus oryzae, Tribolium castaneum, Tribolium confusum, Oryzaephilus surinamensis, Rhyzopertha dominica, Tenebrio molitor, Trogoderma granarium, Acarus siro, and Alphitobius diaperinus represent significant arthropod stored-product pests worldwide. To combat these noxious arthropods, the current study examines the pesticidal effect of essential oils (EOs) derived from four aromatic plants, i.e., Illicium verum Hook. F., Citrus reticulata Blanco, Monodora myristica (Gaertn.) Dunal, and Xylopia aethiopica (Dunal) A. Rich. Considering the challenge of pesticide resistance, the current study focuses on assessing the efficacy of these EOs as an eco-friendly alternative to traditional synthetic insecticides. Two EO concentrations (500 and 1000 µL/kg wheat) were applied to different life stages of these pests in the bioassays. Mortality rates were monitored over several days under controlled environmental conditions. The findings demonstrated that C. reticulata and I. verum EOs had elevated insecticidal effects, especially against larval stages, resulting in 100% mortality in several species. On the contrary, M. myristica and X. aethiopica EOs showed less overall efficacy despite their potency against some pests. Both I. verum and C. reticulata EOs outperformed the positive control, pirimiphos-methyl, in several assays. The results of the current study highlight the potential of several EOs as effective alternatives in reducing synthetic pesticide use for integrated pest control management.

Nano Silicon Modulates Chemical Composition and Antioxidant Capacities of Ajowan (Trachyspermum ammi) Under Water Deficit Condition.

Ajowan (Trachyspermum ammi) is an important spice in the food industry, as a well as a medicinal plant with remarkable antioxidant properties. In this study, its essential oil content, chemical composition, flavonoid content, phenolic content, and antioxidant capacity were evaluated under three irrigation regimes (50, 70, and 90% field capacity) and different amounts of nano silicon (0, 1.5, and 3 mM) in ten populations of ajowan. Based on the GC-MS analysis, thymol, carvacrol, p-cymene, and γ-terpinene were determined as the main components of the oil. The thymol content ranged from 34.16% in the Ardabil population (irrigation at 50% and nano silicon at 1.5 mM) to 65.71% in the Khorbir population (without nano silicon and irrigation at 50%). The highest phenolic content was in Khormo with irrigation at 90% and without nano silicon (172.3 mg TAE/g DW), while the lowest was found in Hamedan (irrigation at 50% and without nano silicon (7.2 mg TAE/g DW)). Irrigation at 50% and no nano silicon treatment led to an increase in total flavonoids in Ardabil (46.786 mg QUE/g DW). The antioxidant activity of ajowan was evaluated using the DPPH assay. Accordingly, the highest antioxidant capacity was observed in Khormo (irrigation at 90% without nano silicon; 4126 µg/mL). Moreover, the highest thymol content was observed in the Khorbir population with irrigation at 50% and without nano silicon treatment. Furthermore, correlation and principal component analysis (PCA) provide new insights into the production of ajowan from their substrates under nano silicon treatment and water deficit conditions. Finally, the results revealed information on how to improve the desired essential oil profile and antioxidant capacity of extracts for industrial producers.

Zinc oxide nanoparticles foliar use and arbuscular mycorrhiza inoculation retrieved salinity tolerance in Dracocephalum moldavica L. by modulating growth responses and essential oil constituents

The production of medicinal plants under stressful environments offers an alternative to meet the requirements of sustainable agriculture. The action of mycorrhizal fungus; Funneliformis mosseae and zinc in stimulating growth and stress tolerance in medicinal plants is an intriguing area of research. The current study evaluated the combined use of nano-zinc and mycorrhizal fungus on the physiochemical responses of Dracocephalum moldavica under salinity stress. The study employed a factorial based on a completely randomized design with three replications. The treatments were different levels of salinity (0, 50, and 100 mM NaCl), two levels of mycorrhiza application (0 and 5 g kg− 1 of soil), and two levels of foliar spraying of nano zinc oxide (0 and 1000 ppm). Salinity decreased the photosynthetic pigments content, SPAD value, and chlorophyll fluorescence data (Fm, Fv, Fv/Fm). Plant dry weight, Na+ content, and essential oil content were significantly higher at 50 mM salinity + co-application of mycorrhiza and nano zinc oxide. Electrolyte leakage increased under salt stress, while mycorrhizal inoculation compensated for the trait. The main essential oil constituents were geranyl acetate, nerol, geranial, geraniol, viridiflorol, hexadecane, humulene, and germacrene D. Energy metabolism demonstrates the effectiveness of treatment combinations in promoting the biosynthesis and accumulation of essential oil components. The overall results with more comprehensive field-based studies would be advisable for the extension section to utilize marginal salty lands for the reliable production of a valuable medicinal plant.

Comparative Evaluation of Different Mint Species Based on Their In Vitro Antioxidant and Antibacterial Effect.

In our research six different mint species (peppermint, spearmint (five different chemotypes), Horse mint, mojito mint, apple mint (two different chemotypes), bergamot mint) have been evaluated by referring to their chemical (essential oil (EO) content and composition) and in vitro biological (antibacterial, antioxidant effect) characteristics. The EO amount of the analyzed mint populations varied between 1.99 and 3.61 mL/100 g d.w. Altogether, 98 volatile compounds have been detected in the oils. Antibacterial effects (inhibition zones, MIC, IC50 and MBC) were evaluated against Escherichia coli, Salmonella enterica, Bacillus cereus and Staphylococcus aureus. The best antibacterial effect was given by a carvacrol-thymol chemotype spearmint population (inhibition zone: 18.00-20.00 mm, MIC: 0.06 v/v%, IC50: 0.01-0.03 v/v%, MBC: 0.06, >2.00 v/v%). The least effective oil in the case of Gram-negative bacteria was bergamot mint (inhibition zone: 7.67-8.67 mm, MIC: 2.00, >2.00 v/v%, IC50: 0.11-0.25 v/v%, MBC: 2.00, >2.00 v/v%), while in the case of Gram-positive bacteria, oils containing dihydrocarvone as the main compound possessed the weakest antibacterial effect (inhibition zone: 9.00-10.00 mm, MIC: 1.00-2.00 v/v%, IC50: 0.22-0.37 v/v%, MBC: >2.00 v/v%). Interestingly, none of the oils could kill B. cereus in the applied concentrations.

Organic fertilization systems on the vegetative growth and essential oil production of Pelargonium graveolens

The aromatic plant Pelargonium graveolens L. 'Hérit, known as geranium, presents bioactive compounds of high economic interest. Since the secondary metabolism is affected by several factors such as the cultivation conditions, this work aimed to assess the impact of different fertilization systems on geranium vegetative growth and essential oil content and yield. The treatments were: T1) chemical fertilization (N-P-K); T2) no fertilization; T3) biodynamic fertilization; T4) organic fertilization; T5) biodynamic fertilization + plant growth-promoting bacteria (PGPB); T6) organic fertilization + PGPB; and T7) organic compost. The application of Azospirillum brasilense (PGPB) had no significant effect on geranium vegetative growth and essential oil production. Essential oil production was not observed in plants treated with chemical (T1) or biodynamic fertilizers (T3 and T5). Plants treated with organic fertilization (T4 and T6) showed greater agronomic development in addition to essential oil content and yield. Consequently, organic fertilization emerges as a promising approach for cultivating P. graveolens.

Allelopathic Influence of Artemisia lancea Essential Oil on Selected Broad and Narrow Weeds

The present study analyzed the chemical composition and phytotoxic activity of Artemisia lancea essential oil (EO). Gas chromatography-mass spectrometry (GC-MS) results showed the presence of 55 compounds, representing 82.36% of the entire EO, with eucalyptol (18.7%) being the most abundant constituent. Phytotoxic bioassay results indicated that the EO (concentration ranging from 0.25-5 mg mL-1) inhibited the growth of Amaranthus retroflexus and Setaria viridis. Root length of A. retroflexus and S. viridis were reduced with the increasing concentration of the EO, especially when the EO was applied at 1-5 mg mL-1. When treated with 1-5 mg mL-1 EO, shoot length of A. retroflexus and S. viridis were also significantly suppressed. The half maximal inhibitory concentration (IC50) values for inhibiting root and shoot growth of A. retroflexus by the EO were 0.284 and 0.246 mg mL-1; for S. viridis, the EO showed IC50 values of 0.44 and 0.262 mg mL-1 for root and shoot inhibition, respectively. The most promising findings were observed when A. lancea EO concentration reached 1 mg mL-1 and higher, which completely inhibited seed germination of A. retroflexus and S. viridis. These findings suggest A. lancea EO has potential as an eco-friendly bioherbicide for agricultural weed control.

Characterization of Aroma Composition of Amomum tsaoko During the Drying Process Based on GC-MS.

Amomum tsaoko is an important spice and medicinal plant widely utilized in East and Southeast Asia. Non-targeted metabolomics techniques were employed to study the variations in the content and composition of essential oil from A. tsaoko during drying at different temperatures: 40°C, 50°C, 60°C, and 70°C. A total of 260 metabolites were detected using gas chromatography-mass spectrometry (GC-MS), mainly terpenoids and aldehydes. Cineole, the most important component, accumulated abundantly in samples dried at 50°C. A higher temperature (70°C) was conducive to the accumulation of aldehydes. Overall, the optimal drying condition for A. tsaoko was determined to be 50°C for 50 h. In addition, nine differential metabolites were screened using variable important in projection and p value (VIP > 1 and p < 0.05), which may serve as potential flavor markers to differentiate various drying treatments of A. tsaoko. This study provides a novel perspective on understanding the dynamic metabolites changes during the drying process, and establishes a theoretical foundation for the refinement and high-quality processing of A. tsaoko.

Evaluation of the chemical composition of fresh and dried pepper (Piper nigrum) produced in Côte D’Ivoire

In this study, we evaluate the chemical quality of fresh and dried pepper grown in Côte d'Ivoire. Sampling was carried out on the basis of pedological data provided by the Association of Côte d'Ivoire Pepper Producers. Samples were then collected over a period of two (2) years. The results show that the fresh and dried pepper samples with the highest water content came from Niablé (69.55%) and Assouba (14.32%) respectively. The highest total sugar values for fresh pepper samples were found in Guibéroua (6.44 mg). Dried pepper samples with the highest total sugar content came from Guibéroua (7 mg). The highest reducing sugar contents in fresh and dried peppers were found in samples collected successively in Niablé (2.86 mg) and Danané (3.20 mg). Fresh pepper samples collected in Lopou (5.58%) showed the highest ash content. Dried pepper samples with the highest ash content were recorded from PK 103 (5.63%). Fresh pepper samples from Maféré (14.33 g) and Azaguié (14.33 g) contained the highest values. The highest protein contents were found in dried pepper samples from Niablé (14.55 g) and Maféré (14.33 g/100g). The highest piperine values were found in fresh pepper samples from Maféré (7.05 g). Dried pepper samples from Maféré (7.36 g) showed the highest piperine content. Fresh pepper samples with the highest essential oil content were from Maféré (1.93 mL). Dried pepper samples from Maféré (7.36 g) had the highest piperine content. Finally, the chemical parameters analyzed are very important for the development of the organism.

Determination of essential oil components of Achillea millefolium

Medicinal plants used in traditional medicine are being investigated and employed more and more in the food, pharmaceutical, and nutraceutical industries these days. Achillea sp. which is in the Asteraceae family is one of the most widely used medicinal and aromatic plants for the treatment of various diseases. Both traditional medicine and modern medicine make extensive use of yarrow (Achillea millefolium L.). The objective of this study was to ascertain the essential oil content and essential oil constituents of Achillea millefolium species, which are found in Ulus Mountain in the Sındırgı district of Balıkesir province. The components of the essential oil were examined using a GC-MS device after the hydrodistillation process as used to obtain it. The analysis revealed a significant concentration of the carvacrol component (10.16 %) in the essential oil of the Achillea millefolium plants. A total of 95 components were identified in A. millefolium essential oil which accounted for 89.95 %. Carvacrol (10.16 %), γ-Muurolene (9.58 %), Grandisol (5.28 %), Artemisia ketone (3.70 %) were found as major constituents of A. millefolium essential oil.

Assessing the effects of water stress and bio-organic fertilizers on English and French Lavandula species in different locations

A study was conducted utilizing a factorial split-plot design within complete randomized blocks to evaluate the effects of water stress (at 95±5, 75±5, 50±5, and 25±5% of the field capacity (FC)) and various fertilizer sources (Azotobacter-Psedomonas Bacterial (APB), arbuscular mycorrhizal fungi (AMFs), and biochar (BI), applied individually and in combination, along with a control treatment on the two species of lavender (French and English) in two distinct climates (Fars and Hamedan) in Iran. The results revealed that severe water deficit stress reduced the growth, yield, and essential oil content in both lavender species. APB+AMFs+BI and APB+BI led to the highest flower yield for French lavender in Fars and Hamedan while subjected to well-watered conditions. The essential oil yield significantly decreased in both experimental regions under 25% FC. Employing APB+BI under 75 and 50% FC treatments led to the highest essential oil content (4.23 and 1.56%, respectively) in English lavender. Linalool showed the highest average (22.46 to 30.06%) in both species. French and English lavender in Fars showed significant differences in fatty acid compositions, but no such differences were reported in Hamedan. APB+BI emerged as the most effective fertilizer combination in terms of total fatty acids and rank index. Simultaneous use of bio-organic fertilizers yielded appropriate results under water-deficient conditions. Finally, the study underscored the strong correlation between climatic parameters such as rainfall and temperature, as well as the efficacy of different fertilizer sources, emphasizing that climatic condition and plant species can significantly impact the effectiveness of fertilizer use.

Effects of harvest time and plant part on essential oils, phenolics, and antioxidant activity in Lippia citriodora

This study investigates the effects of harvest time and plant parts on the concentrations of essential oils, phenolic content, flavonoids, and antioxidant activities (ABTS and DPPH) in the Lippia citriodora plant to determine the best outcome. The experiment consists of four different harvest times during flowering period and two plant parts (upper and lower). Harvest times were scheduled at weekly intervals.Significant variations were observed during experiment, Essential oil (EO) content reached peak value at the first harvest in upper parts of plants (L1U: 1.18%) and lowest value in lower parts by the fourth harvest (L4L: 0.25%). The highest phenolic content determined at the first harvest (L1: 44.04 mg GAE/g DW), while flavonoid levels reached peak value at the fourth harvest (L4: 314.07 mg rutin/g DW). Antioxidant activities, measured by ABTS and DPPH assays, were significantly greater in lower plant parts. Partial Least Squares Discriminant Analysis (PLS-DA) and Principal Component Analysis Discriminant Analysis (PCA-DA) confirmed clear distinctions between the upper and lower parts of the plant regarding bioactive compounds concentrations. The findings shows the importance of targeted harvest timing and plant parts in optimizing bioactive compound in Lippia citriodora, with implications for getting better benefits from plant.

Продуктивность горчицы сарептской яровой в зависимости от подкормок серосодержащим удобрением

In 2020–2022 we studied the effect of ammonium sulphate on the productivity of the spring brown mustard variety Yunona on leached chernozem of the Western Ciscaucasia. It was found that the most effective agricultural practice is the foliar split application of this fertilizer: N21S24 at the seedling stage and N21S24 at the stage of stem extension. This agricultural practice contributed to a significant increase in the main indicators of the crop yield structure: the number of productive branches and pods per a plant by 28.6 and 13.8% respectively; the number of seeds in a pod – by 15.8% and the thousand-seed weight – by 24%. As a result, the crop yield increased by 0.31 t/ha in 2020, 0.44 t/ha in 2021 and 0.43 t/ha in 2022, with a three-year average of 0.39 t/ha. In addition, the oil yield increased by 0.20 t/ha, oil content of seeds by 1.9%, and essential oil content of seeds by 0.06%.

The effects of different color lights on the growth, glandular trichome development and essential oil content of Mentha arvensis L

Mentha arvensis L. is well known for producing the monoterpenes menthol; its essential oil (EO) is widely used in pharmaceutics, cosmetics, food and other industries. The peltate glandular trichome (PGT) is the site responsible for the production and storage of EO in mint. Light is one of the most important environmental factors that contributes to plant growth and development, and secondary metabolism. In this report, we have investigated the influence of additional red light (White + Red, W+R) and blue light (White + Blue, W+B) on the parameters of growth, EO, and PGT in M. arvensis. Interestingly, the plant growth parameters, such as the number of branches, plant height, fresh weight, leaf area and number of leaves were significantly greater both under W+R and W+B treatments compared to the control group. Red light proved more beneficial for increasing plant height (by 15.26%) and fresh weight (by 58.42%), whereas blue light was more effective in boosting the number of branches (by 83.68%) and leaves (by 65.07%). The highest increases in essential oil (EO) content (by 36.36%), yield (by 101.72%), and peltate glandular trichome (PGT) density (by 35.64%) were observed under W+B treatment. However, both W+R and W+B had a slightly negative effect on the quality of mint EO, where menthol content decreased by 4.32 per cent and 11.88 per cent respectively. These results proved that red light is more conducive to biomass accumulation, while blue light is more conducive to EO synthesis and PGT development in M. arvensis.

Influence of ethephon and soil treatments on the essential oil composition of sweet fennel and its biological activities.

The manipulation of cultivation conditions in addition to environmental changes is a key factor affecting the growth, secondary metabolites production, and the biological activity of the plant. Our study aims to evaluate the impact of foliar spray of ethephon, water stress, organic and inorganic fertilizers on the cytotoxic and antimicrobial activities of the fruit oil of Foeniculum vulgare, Miller, var. dulce and its vegetative growth and oil composition. Four different soil treatments were implemented. Gas chromatography coupled with mass spectrometry GC/MS was applied to identify the volatile compounds. Evaluation of both the cytotoxic and the antimicrobial activities of the fruit oil were assessed using the viability assay and the well diffusion method respectively. Variations in the vegetative growth factors and the essential oil (EO) composition were recorded. About a 94.7% increase in the total oil yield was detected in condition 3 compared to control. The oil sample obtained under condition 1 showed the strongest antimicrobial activity against most tested strains and a significant cytotoxic effect against prostate carcinoma (PC-3) cells. Facing the global problem of water deficit, our success in producing a good quality fennel crop and its EO content upon application of drought stress and will be very beneficial at both the economic and the pharmaceutical levels.

Assessing the Impact of Irrigation and Biostimulants on the Yield and Quality Characteristics of Two Different St. John's Wort Cultivars in Their Second Growing Season.

The perennial species Hypericum perforatum, commonly known as St. John's Wort, is well regarded for its medicinal attributes, particularly its strong anti-inflammatory and antidepressant effects. Hypericum perforatum L., commonly known as balsam, is extensively employed in both traditional and contemporary medicine due to its biological properties, although the plant's medicine distribution is limited to Europe and Asia. This study pioneers the investigation of Hypericum perforatum cultivation in a Mediterranean country, specifically Greece, focusing on the effects of irrigation and biostimulants of two distinct genotypes on quantitative (height, drug yield, essential oil yield) and qualitative (essential oil content and composition) characteristics. A field trial was conducted at the experimental farm of the Agrotechnology Department at the University of Thessaly, located in the Larissa region. This study investigated various testing varieties under different irrigation levels and biostimulant applications. The results underscore the importance of customized irrigation and biostimulant strategies in improving yield and quality during the second growing season, establishing a foundation for sustainable agricultural progress. Notably, irrigated treatments significantly increased plant height, dry biomass yield, and essential oil production per hectare. Specifically, the essential oil yields for irrigated treatments were nearly double those of rainfed treatments, with 219 kg/ha for rainfed and 407 kg/ha for irrigated. The genotype played a crucial role in influencing production potential, height, flowering, and essential oil composition, with one variety demonstrating biennial blooming and modified essential oil compounds. While irrigation positively impacted yield, it also reduced certain essential oil compounds while increasing β-pinene content. The effects of biostimulants varied based on their composition, with some enhancing and others diminishing essential oil content. Notably, the biostimulant containing algae with auxin and cytokinin (B2) proved to be the most effective in improving the therapeutic profile. This study offers valuable insights into the cultivation of H. perforatum in a Mediterranean climate, highlighting the necessity for ongoing research into native populations, irrigation levels, biostimulants, fertilization, and other factors that affect crop yield and quality characteristics.

Growth Enhancement and Physiological Responses of Tanacetum balsamita L. by Cerium Oxide, Zinc Oxide, and Activated Carbon Nanoparticles Foliar Treatment Under Salinity Stress

ABSTRACT Salinity damages the plant by creating an imbalance between free radicals and the antioxidant defense system. Plantˈs survival under salinity stress is possible through the changes and adaptation of physiological, biochemical, and anatomical processes. Nanoparticle (NP) treatment under salinity reduces the adverse effects of stress on the plant. To survey the effects of NaCl salinity (zero, 50, and 100 mm) and foliar application of activated carbon, cerium, and zinc oxide nanoparticles (NPs) on the growth and physiological responses of costmary; a factorial experiment was conducted based on a completely randomized design. The results showed that the independent effect of salinity influenced the catalase activity, malondialdehyde (MDA), proline, sodium, and potassium content. Plant aerial part dry weight, essential oil, nitrogen content, and Na/K ratio were influenced by the independent effects of salinity and NP spray. By increasing the salinity stress to 100 mm; the aerial part dry weight of the plant decreased by 36% compared to the control. However, proline and MDA content, and Na/K ratio were increased. The highest content of essential oil was observed in the zero and 50 mm salinity. The results revealed the occurrence of up to 40 compounds in the essential oils. Carvone (49–60.1%) was the main component identified in all treatments, and the highest amount of this constituent was traced in NaCl50 mm × CeO2 treatment. The overall results revealed that costmary was sensitive to salinity stress; however, the NP foliar treatments were potentiated to meliorate the accumulation of some major essential oil constituents even under stressful environments.

Chemical Composition and Antibacterial Effect of Clove and Thyme Essential Oils on Growth Inhibition and Biofilm Formation of Arcobacter spp. and Other Bacteria.

Background: In recent years, significant resistance of microorganisms to antibiotics has been observed. A biofilm is a structure that significantly aids the survival of the microbial population and also significantly affects its resistance. Methods: Thyme and clove essential oils (EOs) were subjected to chemical analysis using gas chromatography coupled to mass spectrometry (GC-MS) and gas chromatography with a flame ionization detector (GC-FID). Furthermore, the antimicrobial effect of these EOs was tested in both the liquid and vapor phases using the volatilization method. The effect of the EOs on growth parameters was monitored using an RTS-8 bioreactor. However, the effect of the EOs on the biofilm formation of commonly occurring bacteria with pathogenic potential was also monitored, but for less described and yet clinically important strains of Arcobacter spp. Results: In total, 37 and 28 compounds were identified in the thyme and clove EO samples, respectively. The most common were terpenes and also derivatives of phenolic substances. Both EOs exhibited antimicrobial activity in the liquid and/or vapor phase against at least some strains. The determined antimicrobial activity of thyme and clove oil was in the range of 32-1024 µg/mL in the liquid phase and 512-1024 µg/mL in the vapor phase, respectively. The results of the antimicrobial effect are also supported by similar conclusions from monitoring growth curves using the RTS bioreactor. The effect of EOs on biofilm formation differed between strains. Biofilm formation of Pseudomonas aeruginosa was completely suppressed in an environment with a thyme EO concentration of 1024 µg/mL. On the other hand, increased biofilm formation was found, e.g., in an environment of low concentration (1-32 µg/mL). Conclusions: The potential of using natural matrices as antimicrobials or preservatives is evident. The effect of these EOs on biofilm formation, especially Arcobacter strains, is described for the first time.