Essential Oil Accumulation Research Articles

Variations in Photosynthesis and Essential Oil in Thyme

Plants of two clonal thymol-type thyme selections were grown under natural light and natural light supplemented by a PPF of 200 μmol m -2 s -1 , provided by HPS lamps at 50%, 70% and 90% soil water amount (SWA) of field capacity in a greenhouse. We investigated the variations in net CO 2 assimilation rates (Pn), dry matter and volatile oil accumulation and their relationships during different development periods. Pn varied between 5.88 to 15.80 μmol CO 2 m -2 s -1 under natural light and from 11.93 to 28.04 μmol CO 2 m -2 s -1 under supplemental light. The highest Pn, 28.04 μmol CO 2 m -2 s -1 , was obtained from ≪Laval-1≫, after 120 days of growth under supplemental light at 70% SWA. The lowest Pn, 5,88 μmol CO 2 m -2 s -1 , was obtained from ≪Laval-2≫, after 40 days of growth under natural light at 50 % SWA. Volatile oil accumulation steadily increased from 0.38 % to 1.35 % under natural light and 0.68 % to 2.18 % under supplemental light, with further development of the plants. Similarly, the dry matter shoot yield grew from 1.31 to 18.20g/plant under natural light and 2.87 to 50.30g/plant under supplemental light, depending on SWA and the time of harvest. We discovered, that mean shoot yield and essential oil accumulation over the growing period were fairly associated with Pn. There were significantly positive correlations between Pn and essential oil accumulation (r 2 = 0.64), shoot yield and essential oil content (r 2 = 0.58) and Pn and shoot yield (r 2 = 0.55).

Comparison Studies onTanacetum vulgareL. Chemotypes

Chemotypes of tansy, Tanacetum vulgare, differing in essential oil composition and morphological properties were examined during ontogeny. In a vegetative cycle the course of essential oil accumulation was similar among all chemotypes, but differences in the accumulation pattern for oil constituents (bomeol, camphor, 1,8-cineole, thujen-acetate, thujone, davanon) during ontogeny and among organs were observed. The differences among chemotypes make consideration of oil composition important when collecting wild plants for oil extraction and when developing cultivation methodology.

The Relation Between Primary and Secondary Metabolism in Peppermint Under Fe-stress

ABSTRACT Changes in growth, (U-14C) sucrose and 14CO2 incorporation in primary photosynthetic metabolic pool under Fe deficiency and recovery in relation to essential oil accumulation have been investigated in Mentha piperita grown in solution culture. In Fe deficiency, CO2 exchange rate, stomatal conductance, oil content, chlorophyll content and chlorophyll a/b (Chl a/b) were significantly affected. Growth data such as leaf area ratio, specific leaf weight, leaf weight ratio and leaf stem ratio indicate the leaf tissue to be more severely effected than stem. In Fe-deficient plants, total 14CO2 incorporation in the oil and primary metabolites significantly decreased. Incorporation of 14CO2 in sugars, amino acids and organic acids was significantly lower than for control plants. In stems, 14CO2 incorporation in amino acids and organic acids was significantly higher in Fe-deficient plants while the incorporation in sugars was similar to that found in control plants. In plants that have recovered from Fe def...

Relationship Between Assimilate Supply and Essential Oil Accumulation in Annual and Biennial Caraway (Carum carvi L.)

ABSTRACT The reported lower essential oil content of seeds of annual caraway compared with seeds of biennial caraway has three possible causes: genetic differences, differences in the location where the two types are grown, and differences in weather conditions during seed filling, since both forms of caraway ripen in a different period of the year. To study these possible causes, we compared essential oil formation in annual and biennial caraway in a greenhouse experiment, thereby excluding differences in location and weather conditions during seed filling. Surprisingly, under these conditions fruits of annual caraway had a higher dry-weight and contained more essential oil than fruits of biennial caraway. Measurement of plant carbohydrate content suggested that this was because more assimilate was available per fruit in annual caraway. It is concluded that there is no genetic barrier preventing annual caraway from reaching an essential oil content similar to biennial caraway. The low essential oil conte...

Light Levels, Growth, and Essential Oil in Dill (Anethum graveolensL.)

The effect of light level on growth and development of dill herb was studied in a greenhouse under full sunlight and under 70, 50, and 30 percent of full sunlight. Decreasing light levels resulted in decreases in leaf number, leaf area, and plant height. Dill growth and essential oil accumulation increased with increases in the light level and was greatest under full sunlight.

Interspecific Variation in Mints for Photosynthetic Efficiency, and 14-C Primary Metabolic Pool in Relation to Essential Oil Accumulation

Summary Interspecific variation in various Mentha species, viz. Mentha arvensis , Mentha cardiaca , Mentha piperita , Mentha spicata and Mentha virdis for photosynthetic efficiency and 14 CO 2 incorporation into the primary metabolic pool and essential oil after 1 and 6 h of CO 2 incorporation have been investigated. There are significant differences among Mentha species in yield characteristics, viz. leaf area ratio, specific leaf weight, leaf weight ratio, and leaf stem ratio and in photosynthetic characteristics, viz. CO 2 exchange rate, stomatal conductance and chlorophyll content. In general, total 14C02 incorporation (ethanol soluble and insoluble fractions) increases from 1 to 6 h with maximum fixation in M. spicata . Most of the incorporation appeared in sugars, sugar phosphates and organic acids, and showed significant changes with time along with changes in 14 CO 2 incorporation in oil. These changes are accompanied by partitioning of 14 CO 2 labelled products into the stem. Oil content showed a significant negative association with 14 CO 2 incorporated in sugars after a 6 h feeding and positive but insignificant association with the photosynthetic rate.

Effect of the triacontanol formulation ?Miraculan? on photosynthesis, growth, nutrient uptake, and essential oil yield of Lemongrass (Cymbopogon flexuosus) Steud. Watts

The influence of different foliar applications of the triacontanol (Tria.) based plant grow regulator-‘Miraculan’, on growth, CO2 exchange and essential oil accumulation in Lemongrass (Cymbopogon flexuosus L.) Steud. Watts. was studied in glass-house conditions. The yield components, viz., plant height, tillers per plant, biomass yield, accumulation of essential oil, net CO2 exchange and transpiration rates increased with ‘Miraculan’ treatment of 0.4 μg/ml compared to the untreated control, but the number of leaves per tiller remained unaffected. Application of Miraculan at 0.4 μg/ml increased micronutrient uptake, total chlorophyll and citral content but decreased chlorophyll a/b ratio and stomatal resistance. Increase in shoot biomass, photosynthesis and chlorophyll were significantly correlated with essential oil content.

INFLUENCE OF PLANTING DATE AND HARVEST TIME ON ARTEMISIA ANNUA L.

Artemisia annua L. is an aromatic and medicinal plant of importance for its volatile essential oils, and the non-volatile artemisinin used in the treatment of malaria. To determine the optimum time of planting for growth and the accumulation of essential oils, seedlings of A. annua (Purdue accession 012) were transplanted into the field in Central Indiana in a RBD with 3 replications on April 25, May 24, June 24, and July 25, 1988. Plant samples were harvested every 2 weeks until first frost.The April and May transplanting dates produced the tallest plants (>180 cm) while the May transplants accumulated the greatest fresh and dry weights. The average increase in plant height was greatest for the June 24 planting date at 9.8 cm per week. Regardless of planting date, all plants began to flower by early August and growth rate began to decrease by late August. Accumulation of essential oil (as rel. % dry wt.) was similar for all planting dates. Essential oil increased until floral initiation, then decreased for 2 weeks after which there was a rapid increase in oil accumulation. Maximum oil accumulation from all planting dates was reached on Sept. 28 after which growth continued to increase.

Light-dependent formation of glandular trichomes and monoterpenes in thyme seedlings

The production of monoterpenes could be induced by irradiating the etiolated seedlings of thyme (Thymus vulgaris) with light. The yield of thymol, the main constituent of the essential oil, increased with increasing time of irradiation. The formation of peltate glandular trichomes (PGTS) occurred prior to monoterpene accumulation in both green and etiolated seedlings. GC analyses of the isolated PGTs showed that monoterpenes were accumulated mostly in the PGTs of cotyledons and primary leaves in green seedlings. Furthermore, the amount of monoterpenes in various organs of the seedlings was closely correlated to the number of PGTS. These results suggested that the primary site of monoterpene accumulation are the PGTS, the formation of which is a prerequisite for the accumulation of essential oils in this plant.

Sucrose metabolism and essential oil accumulation during lemongrass ( Cymbopogon flexuosus stapf.) leaf development

Changes in essential oil and citral content, sucrose metabolizing enzymes such as acid invertase (soluble and cell wall bound), alkaline invertase, sucrose synthase and sucrose/reducing sugar ratio were determined during lemongrass leaf development. The immature leaves (65% of full expansion) possessed the greatest amount of essential oil and percentage of citral. Further development was not accompanied by any net increase in the essential oil pool of the leaf. The ability to synthesize oil and citral from [U- 14C]sucrose decreased greatly much before full expansion. Soluble acid invertase was the major enzyme involved in sucrose breakdown at all stages of leaf development. Its activity increased rapidly during the early stages of leaf expansion, reaching a peak at the time of most rapid oil synthesis and leaf expansion and then declined sharply as the leaf matured. Acid invertase associated with the insoluble fraction followed the same pattern. The activities of alkaline invertase and sucrose synthase were found to be very much lower. Changes in the sucrose to reducing sugar ratio is correlated with changes in acid invertase activity. The phenomenon of essential oil biogenesis is discussed in relation to changes in these physiological parameters.

The accumulation of essential oils by tissue cultures of Pelargonium fragrans (Willd.)

Essential oils are not generally accumulated in morphologically undifferentiated cell suspension cultures. A correlation between morphological differentiation and accumulation is confirmed but it is demonstrated that this level of differentiation is not a prerequisite for product synthesis. In this paper we demonstrate that fine cell suspensions do retain their ability to synthesise essential oils and that accumulation can be induced by manipulation of the photoperiod. It is also shown that morphologically undifferentiated immobilised and aggregate cell systems are capable of essential oil synthesis.

POLYCHEMISMUS BEI ÄTHERISCHÖLHALTIGEN PFLANZENARTEN

Some hypotheses concerning the biological meaning of synthesis and accumulation of essential oils are summarized. Much attention is paid to quantitative and qualitative variation of essential oils and their constituents and to the manifold causes of this variation. The study of variation of essential oil constituents may be a powerful tool in biosystematic research. This is illustrated by a number of recent investigations in which the chemistry of essential oil contributed much to the final interpretation of complex variation patterns. Infraspecific chemical taxa (chemodemes) may be the result of ecogeographic differentiation or of introgressive hybridisation.

On the Distribution of Oil Gland and the Accumulation of Essential Oil in Perilla species

In this paper it is reported that the distribution of oil glands of the leaves and the state of accumulation of the oil drops in the oil glands before and after the coming out of spikes of Perilla species and the cause of lowering of the percentage of oil after the coming out of spikes. 1) The number of oil glands per unit area of the leaves significantly decreases in the direction from the first leaf in the top portion to the 8th leaf with the growth of leaves, which shows a tendency similar to the variation in the rate of oil yield. 2) As a result of the examination of the distribution of oil glands on the whole rear surface of the leaf it has been found that the top portion of the leaf is less in the distribution of oil glands and the neighborhood of the midrib of the basal portion of the leaf is high in the distribution. This tendency is especially significant in young leaves. 3) As the cause of lowering of the rate of oil yield after the coming out of spikes in comparison with that before the coming out of spikes, the distribution density of oil glands (crown portion of each oil gland has formed a cup-like shape) which has small amount of accumulated essential oil may be counted. 4) Since the central portion of oil gland recesses and each forms a cup-like oil gland, in is considered that the essential oil accumulated in the cup-like oil gland has decreased. Judging from the fact that the oil drop in the cup-form oil gland is not dyed red even if it is dyed by sudan IV, it may also be considered that the lowering of the rate of oil yield is due to the change in property of the essential oil.

Effect of Phosphorus Deficiency on Carbohydrate Metabolism of Mentha arvensis

AbstractThe effects of phosphorus deficiency on carbohydrate fractions of Mentha arvensis L. var. piperascens were studied. Mint plants were grown in sand cultures under full nutrition and phosphorus deficiency conditions. Component organs, viz., leaf, stem and root, were sampled at four different stages of the growth cycle and analysed for various sugar fractions.In leaf and root phosphorus deficiency brought about a definite increase in all sugar fractions whereas in stem a reduction was noticed. The stem appeared to be the principal storage organ throughout the growth. Maximum sugar concentration was recorded at the age of 70 days, which represents the full maturity stage, and coincided with maximum essential oil accumulation.