Increase In Essential Oil Yield Research Articles

Effect of Foliar Treatments with Calcium and Nitrogen on Oregano Yield

Oregano, Origanum vulgare L., is a perennial herbaceous plant belonging to the Lamiaceae family. Oregano shows variations in biomass yield and essential oil (EO) content due to the influence of abiotic and biotic factors. The aim of this study was to assess the effect of different foliar applications based on calcium (Ca) and nitrogen (N) on morphological and productive parameters in oregano. Tests were carried out in Sicily (Italy) in 2020–2021. In each year, eight foliar applications were applied. Only flowers and leaves were used for the extraction of the EO. For all parameters in the study, except for plant height and inflorescence length, the highest values were found in treated plants with respect to the control. In plants treated with calcium and nitrogen, an increase of between 0.6 and 1.6 t ha−1 was observed for fresh yield, and an increase of between 0.5 and 0.9 t ha−1 was observed for dry yield. The increase in biomass yield led to an increase in EO yield of between 4 and 12 kg ha−1. The results highlight that foliar treatments with Ca in combination with N enable growth in crop production in environments that show poor water availability.

Seed and Essential Oil Yields of Ducrosia Anethifolia, as Affected by Organic and Chemical Fertilizers

ABSTRACT In order to investigate the effect of organic and chemical fertilizers on quantitative and qualitative traits of Ducrosia anethifolia, a randomized complete block design was carried out with three replications. The experiment was performed with seven treatments including control (no fertilizer), manure (bovine), chemical fertilizers including nitrogen(N), phosphorus (P) and potassium (K), vermicompost fertilizer, thiobacillus bacterium, mycorrhiza fungi, and a combination of mycorrhizal fungi and thiobacillus bacterium (mycorrhiza+thiobacillus). Results showed that fertilizer treatments increased the yield and yield components of the plant compared to the control. Inoculation with thiobacillus, mycorrhiza, and thiobacillus+mycorrhiza resulted in higher levels of seed yield, essential oil yield and percentage, chlorophyll a, b and total and also carotenoids content compared to plants treated with chemical fertilizers. Generally, thiobacillus+mycorrhiza treatment led to more seed yield (8430 kg/ha) and essential oil yield (176.36 kg/ha) than other treatments, showing 62% and 52% increase in seed yield and 80% and 321% increase in essential oil yield in comparison with control and chemical fertilizers, respectively. Based on the results of this research, application of biological fertilizers can control excessive use of chemical fertilizers in sustainable agriculture.

Effects of salicylic acid on growth, mineral nutrition, glandular hairs distribution and essential oil composition in Salvia officinalis L. grown under copper stress

Higher uptake and translocation of copper (Cu) into plant tissues can cause serious physiological and biochemical alterations. Salicylic acid (SA) is a well-known naturally occurring signaling molecule responsible for inducing environmental stress tolerance in plants. Therefore, spraying of SA could provide protection against several types of stresses such as Cu toxicity. In this sense, a pot study was conducted to find out whether spraying of SA (0.5 and 1 mM) could ameliorate the adverse effect of Cu toxicity (40 mM) in Salvia officinalis L. plants. The results showed that the Cu stress significantly decreased the stem and root growth, and it reduced the calcium (Ca), phosphorus (P) and potasium (K) content of leaves and roots. Besides, Cu stress increased essential oil yield by 16.66% as compared to control. On the other hand, SA spraying on stressed plants significantly improved stem and root growth and increased Ca, P and K content. This improvement was more pronounced at 0.5 mM SA concentration. The essential oil content also increased under treatment with SA, specially at 0.5 mM concentration, with 116.66% enhancement as compared to stressed plants (untreated with SA). The increase in essential oil yield under all treatments was associated with significant enhancement in the density of peltate glands, with a much higher density when SA was applied at 0.5 mM concentration in presence of Cu stress. The chemical composition of oil changed according to the treatment. Cu stress led to a reduction of 19% in oxygenated monoterpenes levels, mainly due to the decrease in the major compounds, α-thujone, camphor and 1.8-cineol. However, spraying SA on stressed plants led to the recovery of normal levels of these compounds.

Physiological Response of Fennel (Foeniculumvulgare Mill.) to Drought Stress and Plant Growth Regulators

Implementing strategies for the efficient use of irrigation water is a priority in areas that encounter water shortage. Fennel (Foeniculum vulgare Mill.) is an important medicinal plant grown in many semi-arid regions. A greenhouse study was conducted to investigate the influence of drought stress and the application of three plant growth regulators (PGRs) including jasmonic acid (JA), brassinosteroids (BRs), and putrescine (Put) on photosynthetic parameters, seed yield, essential oil content, essential oil yield, and water use efficiency of seed (WUEseed) of fennel. The results indicated that fennel leaves grown under mild drought stress maintained their relative water content by osmotic adjustment mainly through soluble sugars. Photosynthetic parameters, including leaf chlorophyll index, the maximal quantum yield of PSII photochemistry, net photosynthesis, and transpiration rate were similar in non-stressed plants and mildly-stressed plants prior to flowering. Essential oil content increased in stressed plants, but essential oil yield decreased. WUEseed slightly improved in plants under moderate drought stress. Regardless of the stress level, all three PGRs increased seed yield, primarily by increasing the seed number. Application of BRs, JA, and Put resulted in an approximately 4.2-, 3.5-, and 1.7-fold increase in essential oil yield, respectively. The highest WUEseed (0.82 g/L) was measured in plants that were grown under moderate stress and treated with BRs. Maximum seed yield (2.7 g/plant) was obtained from plants grown under non-stress conditions when treated with JA. It was concluded that spraying fennel plants with PGRs resulted in a considerable increase in essential oil yield.

Suppression of root-knot disease in Pogostemon cablin caused by Meloidogyne incognita in a rhizobacteria mediated activation of phenylpropanoid pathway

Biological control of plant diseases using Plant Growth Promoting Rhizobacteria (PGPR) is an emerging technique, not only because it provides control over the disease, but also acts in an eco-friendly way. In this study the isolated Pseudomonas putida strain, BG2 (KU312064.1) and Bacillus cereus BC1 (KX762284), promoted growth as well as provided resistance to Meloidogyne incognita infection. From the gene expression analysis it was found that both the strains activated phenylpropanoid pathway through – overproduction of Phenylalanine ammonia lyase (PAL) enzyme. Further, the BG2 strain also activates the chalcone synthase enzyme leading to the synthesis of flavonoids, which are known to possess nematicidal activity. We finally concluded that the BG2 and BC1 strains can be a potential biocontrol agent to deal with root-knot disease of Patchouli caused by M. incognita, and of benefit for the overall growth of the plant including increase in essential oil yield.

Changes in essential oil-content and composition of ajowan ( Carum copticum L.) seeds in response to growth regulators under water stress

Abstract Two separate field experiments were conducted in 2014 and 2015. In 2014 changes in essential oil content and in 2015 changes in essential oil composition of ajowan seeds in response to water tress and growth regulators were investigated. The experiments were arranged as split plot based on RCB design in three replicates, with irrigation treatments in main plots and foliar sprays of water (control), salicylic acid (SA) (0 and 1 mM) and abscisic acid (ABA) (0 and 50 μM) in sub plots. In 2014, seeds were harvested in weekly intervals at six stages. With progressing seed development, seeds per plant, seed weight and seed yield enhanced, leading to an increase in essential oil yield, despite decreasing essential oil percentage and per seed. Essential oil percentage increased, but seed and essence yields decreased as a consequence of water stress in both years. Foliar application of ABA and especially SA enhanced essence yield of ajowan seeds via increasing seed yield and essence content. About 70 compounds were identified in essential oil of ajowan seeds, some of which only induced by the water stress and hormonal treatments. Thymol and γ-terpinene were the major constituents of seed essential oil. The terpineol, trans-carveol and tetrathiapentacene were only induced by water stress. The cyclopropane, trans-decalone-1, isopulegone, hexadecanoic acid, linalool and 1-decanol, 2-hexyl- were specifically synthesized in SA treated plants, and β-phellandrene, 3-fluoro-dl-phenylalanine and 1,5-dimethylbicyclo[3.2.1]octane were only found in ABA treated plants. In general, water stress reduced most of the essential oil components, but foliar spray of SA and ABA enhanced percentages of many constituents and their yield per unit area.

Phytochemical, Morphological and Yield Responses of Mentha canadensis to Organic and Nitrogen Fertilizers

The commercial production of essential oil in Mentha actually depends on the nutrient, fertilization and climatic conditions. Mentha canadensis is one of the Mentha species that produces menthol more than other species. In this study, the effects of organic and nitrogen (N) fertilizer to determine phytochemical, morphological and yield responses of this species were investigated. Experiments were carried out in 3 levels of N and combinations of these applied during the growing season of 2015. The result of this study showed that organic and N fertilizers had significantly effects on growth parameters and essential oil yield and content of menthol, menthone and menthofuran. The minimum percentage of menthol was 38.2 in the control and the maximum percentage of menthol was 41.6 in 15: 400 (organic: nitrogen) combination fertilizers. This increase in essential oil yield might be due to either an increase in vegetative growth or changes in monoterpenes biosynthesis.

Microbial interference ameliorates essential oil yield and diminishes root-knot infestation in sweet basil under field conditions

Despite the vast exploration of bioinoculants for disease resistance and crop yield enhancement, knowledge about their impact on quality and quantity of essential oil as well as induction of antioxidant is scarce, especially in medicinal and aromatic crops. In the present two-year field experimentation, a subset of Bacillus spp., namely Bacillus flexus, B. subtilis, B. megaterium and B. aryabhattai, was evaluated against the most devastating root-knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood infestation and essential oil yield enhancement in Ocimum basilicum var. CIM-Soumya (Sweet basil). The plants treated with B. subtilis showed significant (P < 0.05) enhancement in fresh biomass (42%), essential oil content (121%), nutrient uptake (83%) and reduced root-knot infestation (54%) as compared to untreated control. The defence afforded by bioinoculants was observed based on augmentation of the phenolic (97%), flavonoid (93%), free radical scavenging activity (34%) and total antioxidant (33%) in Bacillus-treated infected plants as compared to untreated infected plants. The higher concentration of essential oil constituents, namely linalool (54%) and methyl chavicol (33%), was also recorded in same treatment. An increase in essential oil yield was reflected by induction of antioxidant machinery. The present study for the first time delineates nematicidal potentials of B. flexus and B. aryabhattai. Altogether these findings suggest that exploitation of bioinoculants could be helpful for effective management of the root-knot nematode infestation along with higher qualitative and quantitative essential oil yield with augmented antioxidants in sweet basil.

Enrichment of marigold (Calendula officinalis) seeds influences seedling vigor and essential oil yield in flowers

Most of soils in Iran are deficient in micro-elements. Enrichment of seeds is found to be as suitable method for overcoming micronutrient deficiencies. Marigold is a herbal medicinal plant. In order to study evaluate of seed enrichment by some of micro-nutrients on seedling establishment and yield of marigold two laboratory and field experiments were carried out on marigold (Calendula officinalis L.) at the Islamic Azad University, Tabriz, Iran, during 2012. Treatments were 0.5%, 1%, 1.5% and 2% Zinc or Manganese, such as 14.5, 29, 43.5 and 58 g Zinc or 19, 38.5, 58 and 77 g Manganese per liter water, respectively. Each treatment involved weighing nearly 10 g of the seed in a glass cup, adding 20 m L of the priming and allowing the seed + solution mixture to sit covered with plastic. Enrichment at the concentrations of 1%; 1.5%, 2% of zinc or manganese increased final germination percentage of marigold seeds in comparison to the control. The data show that mean seedling vigor index can be increased by seed enrichment with zinc sulfate and manganese sulfate, compared to the control. Seeds enriched in 1% Zinc had higher seedling vigor index, but a greater improvement in the Zinc concentration of the solution did not further increase in seedling vigor index. When seeds primed in the highest concentration of manganese, marigold statistically produced flower yield similar to unprimed treatment. Significant increase in essential oil yield of marigold due to seed enrichment treatments relative to not-enrichment was expected. Enrichment of marigold seeds positively influenced seedling vigor and essential oil yield in flowers.

'On-farm' seed priming with Zn+Mn is an effective way to improve germination and yield of marigold

One of the major crop productivity constraints in the world is the unavailability of crop nutrients in appropriate amount and form to crops. In order to study the effect of seed priming with zinc and manganese on germination and essence of marigold in laboratory and field seed priming experiments were done at the Research Station of Islamic Azad University, Tabriz, Iran, with marigold (Calendula officinalis L.), using solutions at four concentrations of zinc and manganese. The priming solution concentrations were 0.5, 1, 1.5 and 2% Zn or Mn, that is, 14.5, 29, 43.5 and 58 g Zn L-1 or 19, 38.5, 58 and 77 g Mn L-1, respectively. Each treatment involved weighing approximately 10 g of the seed in a plastic cup, adding 20 mL of the priming solution, and allowing the seed/solution mixture to sit covered with plastic for 12 h. The essential oil from marigold flowers was isolated by hydro distillation using Clevenger's apparatus. All data was statistically analyzed using MSTAT-C software. Results showed that priming at the concentrations of 1%, 1.5% Zn,1% Mn, or 1% Zn+1.5% Mn increased germination rate of marigold seeds compared to an unprimed control. It is revealed that seed priming with ZnSO4 and MnSO4 may give better results on seedling vigor index of marigold. The highest yield was obtained from seed soaking treatments in 1% Zn+1.5% Mn, 1.5% Zn, 1% and 1.5% Mn solutions. When seeds primed in the highest concentration of Mn, marigold statistically produced flower yield similar to unprimed treatment. Flower essential oil yield among treatments ranged from 0.12 to 0.27mL per 100 g dry weight in 0.5% Mn and 1% Zn+1.5% Mn solutions, respectively. All the seed treatments gave a significant increase in essential oil yield over control. The data from this study confirm that simple 'on-farm' seed priming with Zn+Mn is an effective way to improve germination and yield of marigold. Key words: Essential oil, flower yield, hydro distillation, unprimed treatment.

Elevated atmospheric CO 2 decreases oxidative stress and increases essential oil yield in leaves of Thymus vulgaris grown in a mini-FACE system

Potted one-year-old plants of Thymus vulgaris L. (thyme, Lamiaceae, C3 metabolism), were grown for three months (10 June–10 September, 2004) in a “mini-free-air-CO 2-enrichment” (“mini-FACE”) system, under 500 μmol mol −1 and ambient concentrations of atmospheric carbon dioxide (CO 2). Compared to ambient CO 2, elevated CO 2 stimulated leaf superoxide dismutase (SOD, EC 1.15.1.1) activity only at the first sampling-time (July), followed by no variation or even a trend of decreased activity on the other two sampling-times (August and September). Under high CO 2, guaiacol peroxidase (GPX, EC 1.11.1.7) and catalase (CAT, EC 1.11.1.6) leaf activities showed no variation or drop throughout the duration of the experiment. By contrast, under elevated CO 2, leaf glutathione reductase (GR, EC 1.6.4.2) activity increased on all the sampling-times, and also a duration-dependent upward trend of glutathione (GSH) content was recorded, with this increase becoming significant – compared with ambient CO 2 – at the third sampling-time (September). Simultaneously, leaves from plants grown under high CO 2 showed a marked increase in essential oil yield, with slight increments in phenolic component and decrements in mono- and sesquiterpene components. Also, a drop in thiobarbituric acid reactive substances (TBARS) content under elevated CO 2 was displayed. Thus, in general, the results reported here point to a downregulation of leaf antioxidant enzymes under elevated CO 2, supporting the notion of reduced reactive oxygen species (ROS) formation under these circumstances. Relying instead on antioxidant-regenerating enzymes, namely GR, fairly high GSH content and essential oils, might be a ‘low cost’ life strategy for growth under elevated CO 2, not requiring synthesis/activation of energy-intensive and expensive metabolic processes.

Growth, yield and essential oil content of three cultivars of basil grown under different levels of nitrogen in the field

A field experiment was conducted in Southern Italy to investigate the effect of different nitrogen (N) rates (0, 100 or 300 kg ha −1) on the number of branchings and leaves per plant, plant height, yield of above-ground fresh biomass, total leaf area, dry weight, leaf-to-stem ratio, leaf essential oil content and the essential oil quality at commercial harvest (full bloom) of the three cultivars of basil ( Ocimum basilicum L.): (i) “Mostruoso mammouth” (MM); (ii) “Genovese profumatissimo” (GP); (iii) “Napoletano a foglia di lattuga” (NFL). Nitrogen fertilization up to 300 kg ha −1 increased yield of above-ground and leaf fresh biomass, leaf essential oil yield, but it did not affect leaf-to-stem ratio, plant height and the number of branchings per plant. The increase in essential oil yield induced by N fertilization depended on an increase in both leaf essential oil concentration and leaf biomass. The increase in LAI with increasing N fertilization was due to an increase in leaf number per plant rather than in individual leaf expansion. The cultivar GP was different in morphology from MM and NFL, since it had greater leaf number and plant height, but lower leaf-to-stem ratio and LAI. The physiological efficiency of N use (PE) in producing above-ground biomass was not related to N application whereas PE in producing essential oil (PE-oil) tended to increase with increasing levels of N applied. With regard to the effect of the cultivar, GP was less efficient in N use for oil production than MM and NFL since PE-oil of GP was lower while leaf N and PE-biomass were higher than the other cultivars. NFL was the richest in methyl chavicol but the lowest in linalool, whereas MM and GP contained linalool and eugenol.

Optimization of water and nitrogen application to menthol mint ( Mentha arvensis L.) through sugarcane trash mulch in a sandy loam soil of semi-arid subtropical climate

Studies were carried out to optimize the use of water and nutrients by the crop with three moisture regimes [0.9, 1.2 and 1.5 irrigation water:cumulative pan evaporation (IW:CPE) ratios], two variables of organic mulch (control and sugarcane trash at 7 t/ha) and three levels of nitrogen (0, 100 and 200 kg/ha). Soil moisture regimes maintained at 1.2 IW:CPE ratio significantly increased the crop growth and herb and essential oil yields as compared with that of 0.9 IW:CPE ratio. The increase in herb yield due to 1.5 and 1.2 IW:CPE ratios was recorded to be 28.5% and 19%, respectively, over the irrigation given at 0.9 IW:CPE ratio, with the corresponding increase in essential oil yield to the extent of 23.5% and 15.5%. Interaction effect of moisture regimes and nitrogen rates indicated that increasing levels of irrigation at the highest level of N (200 kg/ha) improved essential oil yield of the crop. Application of N at 200 kg/ha in the mulched plots significantly enhanced the N uptake by the crop and essential oil yield over the control and 100 kg N/ha applied in the mulched/or unmulched plots and 200 kg N/ha applied in the unmulched plots. Application of organic mulch and nitrogen at 200 kg/ha improved the water use efficiency (WUE) in menthol mint crop. Higher moisture regimes maintained up to 1.2 IW:CPE ratio increased the WUE. The quality of essential oil in terms of its major constituent, menthol, improved slightly with 1.2 IW:CPE ratio as compared to 0.9 and 1.5 IW:CPE ratios at first and second harvests of the crop. It is recommended that menthol mint crop could be grown profitably by providing 16 irrigations, that is 80 cm water (based on 1.2 IW:CPE ratio) and nitrogen at 200 kg/ha in the sugarcane trash mulched plots, which could give a highest benefit:cost ratio from menthol mint cropping.

Medicinal and aromatic plant materials as nitrification inhibitors for augmenting yield and nitrogen uptake of Japanese mint (Mentha arvensis L. Var. Piperascens).

Pot experiments were conducted to evaluate the relative performance of medicinal and aromatic plant materials and dicyandiamide (DCD) as nitrification inhibitors to regulate transformation of N from urea. Their effect on the efficiencies of use of N by Japanese mint (Mentha arvensis cv. Hy 77) was tested. Urea was coated with these materials viz., Mentha spicata, Artemisia annua or DCD at the rate of 5% (w/w) of fertilizer urea using an appropriate coating technique. Nimin (tetranortriterpenoids, an ethanol extract of neem (Azadirachta indica Juss) coating was done at the rate of 1% w/w of urea. Fertilizer nitrogen was applied at 100 and 200 mg kg(-1) soil. These natural coating materials significantly increased the herb and essential oil yields of the crop at both rates of fertilizer nitrogen compared to urea alone and were found to be as effective as DCD in retarding NO3- formation in soil. Herb yield increased by 6-81% when compared to uncoated urea. The increase in essential oil yield ranged between 3% and 68% due to coating. The effectiveness of the nitrification-inhibitor--coated urea, however, varied with the soils used and the rate of fertilizer nitrogen applied. The results suggest that the natural products could be potential nitrification inhibitors for increasing fertilizer N use efficiency.

Irrigation and nitrogen requirements of Bergamot mint on a sandy loam soil under sub-tropical conditions

A field experiment was conducted with Bergamot mint ( Mentha citrata Ehrh) var. Kiran at Lucknow, India in 1992 and 1993 under four soil moisture regimes (0.6, 0.9, 1.2 and 1.5 irrigation water: cumulative pan evaporation (IW:CPE) ratio) and four levels of nitrogen (0, 80, 160, 240 kg ha −1). Soil moisture regimes maintained at 1.2 IW:CPE ratio significantly increased the crop growth, and herb and essential oil yields as compared with those having 0.6 and 0.9 IW: CPE ratio. The former produced 86.4% and 10.0% higher fresh herbage than the latter two moisture regimes, with a 63% and 12.7% increase in essential oil yield, respectively. Application of 160 kg N ha −1 was found to be the best with respect to the yield of the crop, but increased levels beyond this did not cause deleterious effects on the synthesis of monoterpenes in the essential oil. High moisture regimes maintained during summer months proved significantly better for efficient utilization of water and nutrient by the crop. The quality of the essential oil in terms of its two major constituents, linalool and linalyl acetate increased favourably up to 1.2 IW:CPE ratio, while the former decreased and the latter improved slightly with the higher moisture conditions prevailed during both the harvest. Higher rate of N fertilization (240 kg ha −1) favoured the synthesis of linalool, a major constituent of essential oil only during the first harvest. It is concluded that the Bergamot mint should be irrigated at 1.2 IW:CPE ratio with an application of 160 kg N ha −1 in the sub-tropical climate of India

Influence of herbicides and growth regulators on the growth and essential oil content of sage

Foliar application of a wide range of herbicides provided suggestive evidence for a direct correlation between growth and essential oil production in sage ( Salvia officinalis) grown under controlled environmental conditions. Conversely, foliar application of the growth regulators AMO-1618 and DCPA indicated that moderate stunting of growth was associated with an increase in essential oil yield. Quantitative changes in the principle monoterpenes of sage oil, β-pinene, 1,8-cineole, 3-isothujone and camphor, were also observed in response to the various treatments. However, attempts to correlate the changes in oil composition with alteration in growth or oil yield also failed to establish any definitive relationships. Since the four monoterpene components examined arise by independent routes from a common precursor, the changes in oil composition observed indicate that the applied bioregulators exert a direct effect on terpene metabolism by a means independent of growth or development.