Total Oil Yield Research Articles

The essential oil of Anemia tomentosa (Savigny) Sw. var. anthriscifolia (Schrad.) Mickel

AbstractThe essential oil composition of the aerial parts of Anemia tomentosa var. anthriscifolia (Anemiaceae) was characterized by GC–MS. Total volatile oil yield extracted by steam distillation was 0.2% dry weight basis. The volatile oil was composed mainly of sesquiterpenes (75%, as the relative percentage of the total essential oil) with lower amounts of monoterpenes (15%); no phenylpropanoids were detected. The sesquiterpenes were composed mainly of oxygenated components (67%), including α‐bisabolol (51%), spathulenol (1%), caryophyllene oxide (3%), α‐bisaboloxide (1%) and 14‐hydroxy‐9‐epi‐(E)‐caryophyllene (1%). The monoterpenes were dominated by neral (5%) and geranial (7%), with lower amounts of α‐pinene, camphene, 6‐methyl‐5‐hepten‐2‐one, 1,8‐cineole and pinocarveol. This is the first report of the essential oil accumulation (0.2%) and volatile composition in the aromatic fern A. tomentosa. Copyright © 2004 John Wiley & Sons, Ltd.

Chemical profiles of primary and secondary essential oils of palmarosa ( Cymbopogon martinii (Roxb.) Wats var. motia Burk.)

Natural essential oils extracted from aromatic crops through steam distillation are extensively used in fragrance, flavour and pharmaceutical industries and in aromatherapy. During steam distillation, a part of the essential oil becomes dissolved in condensate or distillation water and is lost as this water is discarded. A method was developed to recover the dissolved essential oil from condensate water. Palmarosa ( Cymbopogon martinii (Roxb.) Wats. var. motia Burk., family: Poaceae), an important aromatic grass was used as the test crop. The distillation water of palmarosa mixed with hexane in 10:1 proportion was thoroughly shaken for 30 min to trap the dissolved essential oil. Hexane was then distilled to yield ‘secondary’ or ‘recovered’ oil. In palmarosa, the ‘primary’ or ‘decanted’ oil (obtained directly by distilling the crop biomass) accounted for 92% and the recovered oil accounted for 8% of the total oil yield. The solvent loss in this process was 4–7%. Experiments conducted in the laboratory with the essential oil showed that the water solubility of palmarosa oil ranged from 0.12 to 0.15% at 31 °C and 0.15 to 0.20% at 80 °C. Hexane recovered up to 97% of the dissolved essential oil in water. The recovered essential oil was richer in organoleptically important oxygenated compounds linalool (2.6–3.8%), geraniol (91.8–92.8%) and geranial (1.8–2.0%) compared to the primary oil.

Effect of organic agriculture practices on the volatile aroma components of some essential oil plants growing in Egypt II: sweet Marjoram (Origanum marjorana L.) essential oil

AbstractSweet marjoram (German type) was grown in Egypt under the conditions of organic and traditional agriculture. Mature compost was used as an organic fertilizer, while ammonium sulphate was used as a chemical fertilizer. Two levels of each fertilizer were used during plant growth. The crops were harvested and hydrodistilled in June and September, the isolated essential oil was fractionated into oxygenated and hydrocarbon fractions, then each fraction was analysed by GC and GC–MS. The results showed that the fresh herb of marjoram plants positively responded to increased levels of either organic or chemical fertilizers. The herb yield was the highest in the September harvest. Although the higher level of organic fertilization negatively affected the oil content in the fresh herb, however, the total oil yield per plant remained comparable with the lower levels of both organic or chemical fertilization. Regarding the oil composition, the results showed that marjoram (German type) grown in Egypt belongs to the cis‐sabinene hydrate/terpinene‐4‐ol chemotype. The chemical composition of marjoram essential oil did not change due to the fertilization type or level, but rather the relative percentage of certain constituents were affected. The highest concentration of cis‐sabinene hydrate (24.1%), under organic treatment was reported for a June crop fertilized at level I, while the highest concentration of terpinene‐4‐ol, (39.5%), under the same treatment, was detected in a June crop at level II fertilization. Other components showed different concentrations depending on season of harvesting, treatment, and level of fertilization. Copyright © 2003 John Wiley & Sons, Ltd.

Evaluation of agronomically useful somaclonal variants in Jamrosa (a hybrid Cymbopogon) and detection of genetic changes through RAPD

Among 100 somaclones of jamrosa screened, a wide range of variation was recorded for several traits, including plant height, tiller number, herb weight, oil content and total oil yield. Qualitative analysis of essential oil was carried out for 45 somaclones which performed better or equal to the donor parent. Eleven somaclones selected on the basis of total oil yield and quality were further evaluated in replicated trial. Five superior somaclones showing a total oil yield twofold than the donor and possessing quality oil containing a high geraniol content >84% were selected for further analysis in the field for six clonal propagations. Out of the five superior somaclones two improved somaclones which showed relative stability in oil yield and quality were subjected to RAPD analysis. Changes in RAPD banding pattern in the improved somaclone as compared to donor parent revealed occurrence of gross genetic changes.

Possibility of Increased Oil Yield in the NEDOL Process

A maximum oil yield in the NEDOL coal liquefaction process was obtained with coal containing 76−78% carbon, while gas and water yields decreased with an increase in the carbon content. On the other hand, residue yield increased with an increase in the carbon content and this was attributed to an increase in asphaltene [(hexane insoluble)−(toluene soluble)] in the residue. From the experimental results, it was inferred that decomposition of the asphaltene is inevitable for improvement of the oil yield and that prolonged residence time in the liquefaction reactors is the most effective and practical measure for decomposing the asphaltene under the operating conditions of the NEDOL process. The average structure of the hexane soluble, asphaltene and preasphaltene [(toluene insoluble)−(THF soluble)] in the liquefaction residue exhibited the similar structural parameters in coals tested in the NEDOL coal liquefaction plants. The asphaltene fraction was then extracted from the residue by commercially applicable extraction conditions following which the extract was hydrotreated. About 35% of the extract was recovered as oil, which is lighter than 811K boiling point, by hydrotreatment. Furthermore, coal liquefaction experiments that used the extract as a part of solvent were conducted and an increase in total liquefaction oil yield was confirmed comparing with a coal liquefaction experiment without the extract.

Biomass yield, essential oil yield and essential oil composition of rose-scented geranium ( Pelargonium species) as influenced by row spacings and intercropping with cornmint ( Menthaarvensis L.f. piperascens Malinv. ex Holmes)

Rose-scented geranium ( Pelargonium species, family, Geraniaceae) is a vegetatively propagated (through rooted stem cuttings), initially slow growing, high value aromatic crop. Cornmint ( Mentha arvensis L. f. piperascens Malinvaud ex Holmes, family, Lamiaceae) is also a vegetatively propagated (through rhizomes, runners or stolons and terminal stem cuttings), high demand aromatic–cum–medicinal crop. Essential oils isolated through steam distillation of shoot biomass of these two crops are extensively used in fragrance, flavor, and pharmaceutical industries and in aromatherapy. A field experiment was carried out during the vegetation periods of 1996–1998 in semi-arid tropical climate to investigate the influence of different row spacings (60×30, 75×30, 90×30 and 120×30 cm) and intercropping cornmint cv. Shivalik on the biomass yield, essential oil yield and essential oil composition of rose-scented geranium cv. Bourbon. The row spacing of 60×30 cm (60 cm between rows and 30 cm between plants within the rows) was superior to other row spacings and produced 57.4 t/ha total (total of four harvests) biomass yield (132.4% higher than 120×30 cm spacing) and 52.7 kg/ha total essential oil yield (98.9% greater than 120×30 cm spacing). Intercropping of cornmint did not affect biomass yield and essential oil yield of rose-scented geranium and yielded 5.6 t/ha of biomass and 21.3 kg/ha of essential oil of cornmint as bonus yields over and above that of rose-scented geranium. However, biomass yield and essential oil yield of intercropped cornmint suffered reductions of 53.4 and 59.1%, respectively, compared with monocropped cornmint. Intercropping controlled weed growth and decreased total (total of three harvests) biomass yield of weeds by 40.0% in rose-scented geranium intercropped with cornmint. The chemical composition of essential oils of both the crops was not influenced either by row spacings or by intercropping. The quality of essential oils of both the crops was good and was readily accepted in the market.

Water soluble fractions of rose-scented geranium ( Pelargonium species) essential oil

The essential oil of rose-scented geranium ( Pelargonium species, family: Geraniaceae) obtained through steam or water plus steam distillation of shoot biomass is extensively used in the fragrance industry and in aromatherapy. During distillation, a part of the essential oil becomes dissolved in the distillation water (hydrosol) and is lost as this hydrosol is discarded. In this investigation, hydrosol was shaken for 30 min with hexane (10:1 proportion) and the hexane was distilled to yield `secondary' or `recovered' essential oil. The chemical composition of secondary oil was compared with that of `primary' oil (obtained directly by distilling shoot biomass of the crop). Primary oil accounted for 93.0% and secondary oil 7.0% of the total oil yield (100.2 ml from 100 kg green shoot biomass). Fifty-two compounds making up 95.0–98.5% of the primary and the secondary oils were characterized through gas chromatography (GC) and gas chromatography–mass spectroscopy (GC–MS). Primary oil was richer in hydrocarbons (8.5–9.4%), citronellyl formate (6.2–7.5%), geranyl formate (4.1–4.7%), citronellyl propionate (1.0–1.2%), α-selinene (1.8–2.2%), citronellyl butyrate (1.4–1.7%), 10- epi-γ-eudesmol (4.9–5.5%) and geranyl tiglate (1.8–2.1%). Recovered oil was richer in organoleptically important oxygenated compounds (88.9–93.9%), commercial rhodinol fraction (74.3–81.2%), sabinene (0.4–6.2%), cis-linool oxide (furanoid) (0.7–1.2%), linalool (14.7–19.6%), α-terpineol (3.3–4.8%) and geraniol (21.3–38.4%). Blending of recovered oil with primary oil is recommended to enhance the olfactory value of the primary oil of rose-scented geranium. Distillation water stripped of essential oil through hexane extraction can be recycled for distilling the next batch of rose-scented geranium.

CULTIVATION OF MEDICINAL AND AROMATIC PLANTS IN INDIA - A COMMERCIAL APPROACH

CULTIVATION OF MEDICINAL AND AROMATIC PLANTS IN INDIA - A COMMERCIAL APPROACH

Biomass and essential oil yields of rainfed palmarosa ( Cymbopogonmartinii (Roxb.) Wats. var. motia Burk.) supplied with different levels of organic manure and fertilizer nitrogen in semi-arid tropical climate

A field investigation was carried out for 2 years (1994–1996) on a red sandy loam soil in the semi-arid tropical climate of South India, to study the influence of different levels of farm yard manure (FYM) (0 and 15 t/ha per year) and fertilizer nitrogen (0, 40, 80 kg N/ha per year) on the biomass and essential oil yields of palmarosa ( Cymbopogon martinii (Roxb.) Wats. var. motia Burk., family, Poaceae) grown under rainfed condition. During the period of investigation, palmarosa gave seven harvests in 2 years with 23.6–37.2 t/ha total (total of seven harvests) biomass yield, and 99.2–159.1 kg/ha total essential oil yield per hectare. Application of FYM at 15 t/ha per year increased the total biomass yield by 10.7% and total essential oil yield by 10.3% over control (no application of FYM). Addition of nitrogen (N) at 80 kg/ha per year enhanced the total biomass yield by 57.6% and total essential oil yield by 60.3% in comparison to no N application. The quality of the essential oil with 1.7% (E)-β-ocimene, 2.5% linalool, 73.1% geraniol, 15.8% geranyl acetate and 2.0% β-caryophyllene was found to be good and was readily accepted in the market.

Effect of residual sodium carbonate in irrigation water on the soil sodication and yield of palmarosa ( Cymbopogon martinni) and lemongrass ( Cymbopogon flexuosus)

The effects of residual sodium carbonate (RSC) in irrigation water on soil sodication and yield and cation composition of palmarosa ( Cymbopogon martinii Roxb. Wats) and lemongrass ( Cymbopogon flexuosus Steud Wats) were studied in the open bottom reinforced concrete cemented (RCC) cylindrical barrels embedded in the field and filled with sandy loam soils. The results indicated that the increasing RSC in irrigation water significantly increased the pH, electrolyte conductivity (ECe) and SARe of the soil and, hence, considerably decreased the herb and oil yield of both the palmarosa and lemongrass. The reduction in total herb yield was 14.5, 18.3, 28.8 and 32.0% in palmarosa and 38.6, 46.0, 57.7 and 62.6% in the lemongrass over control at 4.0, 8.0, 12.0 and 16.0 meq/l of RSC, respectively. The total oil yield of palmarosa increased by 22.6% with the increase in RSC from 2.0 (control) to 4.0 meq/l and further increase in RSC decreased the oil yield by 13.0, 22.4 and 22.9% over control at 8,12 and 16 meq/l of RSC, respectively. The total oil yield of lemongrass was decreased by 27.0, 39.4, 47.7 and 50.8% over control at 4, 8, 12 and 16 meq/l, respectively. The concentration of Na increased significantly and K and Ca decreased with increase in RSC of irrigation water in vegetative tissues of both species. The lemongrass accumulates significantly greater amount of Na in shoot tissues as compared to palmarosa and it failed to survive at high RSC after 21 months of transplanting. The results suggests that palmarosa is more tolerant to irrigation water sodicity than the lemongrass.

Response of lemongrass ( Cymbopogon flexuosus ) under different levels of irrigation on deep sandy soils

The growth and herbage and oil production of East Indian lemongrass (Cymbopogon flexuosus) in response to different levels of irrigation water (IW) [0.1, 0.3, 0.5, 0.7, 0.9, 1.1, 1.3 and 1.5 times cumulative pan evaporation (CPE)] were evaluated on deep sandy soils at the research farm of the Central Institute of Medicinal and Aromatic Plants, Lucknow, from 1991 to 1993. In general, an increment in the level of irrigation increased the plant height up to 0.7 IW:CPE ratio. The response of irrigation levels on tiller production of lemongrass differed with the season of harvest. Maximum tillers/clump during the 2nd, 3rd, 6th and 7th harvests were in response to irrigation levels 0.9, 0.5, 0.7 and 0.7 IW:CPE ratio, respectively. Oil content had an inverse relationship with the levels of irrigation, specially during the 1st, 2nd, 5th and 6th harvests. Significantly higher herb and essential oil yields were recorded at 0.7 IW:CPE ratio, irrespective of season of harvest. The maximum total herb (22.79 t/ha in first year and 33.11 t/ha in second year) and oil (146.2 l/ha in the first year and 205.3 l/ha in the second year) yields were recorded at 0.7 IW:CPE ratio. The quality of oil with respect to the major chemical constituents (Citral-a, Citral-b and geraniol) was not changed. At the optimum level of irrigation (0.7 IW:CPE ratio) the water used by lemongrass was 118.2 cm for first year and 123.8 cm for the second year. Water-use efficiency was found to be higher (1.66 l oil/ha-cm) in the second year than the first year (1.23 l oil/ha-cm). For optimum yield potential of lemongrass on deep sandy soils of sub-tropical climate, the crop received 17 irrigations in the first year and 14 irrigations in the second year of harvests. Irrigations were made during the dry winter and summer months.

Seed quality of sweet white lupin ( Lupinus albus) and management practice in eastern Canada

White lupin ( Lupinus albus) has shown considerable yield potential as a spring-sown grain legume in eastern Canada and the northern USA. However, the effects of agronomic factors on seed protein and oil of white lupin cultivars have not been quantified under such short growing season conditions. The objective of this research was to determine appropriate management practices for production of better quality sweet white lupin. A 2-year study was conducted in eastern Canada to determine the responses of seed protein and oil in two large-seeded white lupin cultivars (Primorski and Ultra) to management factors. The two lupin cultivars were factorially combined on two soil types, with two planting dates and two row spacings. Of the 2 years, 1991 was more or less typical for the region, while 1992 was unusually cool and rainy. Both lupin protein and oil concentrations were not affected by the tested management factors over three of the 4 location years, except that the early planting date decreased the protein concentration of seeds in pods formed on the stem. The protein yield of seeds in pods formed on the branches was more sensitive to management factors in both sites in 1991. Total protein and oil yields of Ultra were higher than those of Primorski in the typical year (1991), but not in the atypically cool year (1992). On average, protein and oil yields were 59 and 93% higher, respectively, under the cooler climate conditions of 1992 than in 1991. The seed protein:lipid ratio in white lupin seeds was ≈4:1 and 3:1 in 1991 and 1992, respectively. In general, early planting in narrow rows resulted in the highest yields of both protein and oil.

Response surfaces of total oil yield of turmeric ( Curcuma longa) in supercritical carbon dioxide

The process variables pressure, temperature and flow rate were studied for optimisation of total oil yield by response surface methodology following a Box–Behnken design of experiments. The results indicated: (a) a rise in the temperature of extraction leads to decrease in oil yield. (b) The optimum pressure for the extraction of oil was found to be 22.5 MPa. (c) general increase in oil yield with an increase in flow rate. The experimental oil yield is in good agreement with the predicted one. The response surface methodology used in this study was able to predict the optimal extraction conditions for the total yield of turmeric oil.

Biomass and essential oil yields of cornmint ( Mentha arvensis L. f. piperascens Malinvaud ex Holmes) planted in different months in semi-arid tropical climate

A field experiment was conducted in the farm of Mr Jayanthilal Sachdev, a progressive farmer on a red clay loam soil in the semi-arid tropical climate of South India, to study the influence of planting cornmint ( Mentha arvensis L. f. piperascens Malinvaud ex Holmes, family: Lamiaceae) in different months on its biomass and essential oil yields. In this climate, cornmint was harvested six–seven times in a period of 17–18 months. August (rainy), November (autumn), and December (winter) planted crop produced significantly superior total biomass and essential oil yields compared to September and January planted cornmint. The results indicated the feasibility of intercropping cornmint with tomato (6.3 t/ha) during the first harvest period. The quality of the essential oil with 73.0% menthol, 9.6% menthone, 4.0% isomenthone, and 4.0% menthyl acetate was found to be good and readily accepted in the market. This investigation in a farmer’s field with 42.5–63.5 t/ha total biomass yield and 196.3–271.5 kg/ha total essential oil yield, clearly demonstrated the economic feasibility of cultivating cornmint in semi-arid tropical climate. It has also shown the possibility of planting the crop during different seasons and growing it as a biennial.

The effects of water stress on the chemical composition of soybean shoot parts at different growth stages and assimilate distribution to the seeds at different nodal positions

The response of soybean [Glycine max (L) Merrill] cv. Akiyoshi to three moisture levels at three growth stages was investigated in a glasshouse experiment. Percent leaf nitrogen was reduced by water deficit at late flowering and early podding but increased after rewatering. This parameter was not affected by water deficit at early flowering. Percent total available carbohydrate in the stem was reduced by water deficit except at late flowering but also increased after rewatering. Plants subjected to water deficit after early podding had higher available carbohydrate in the stem at maturity. Percent oil content was slightly increased in the seeds of plants subjected to water stress at early podding but percent protein was generally reduced by water stress. Total oil and protein yields were reduced by water deficit at all stages of growth. 14C retention was highest in the seeds of the main stem and lowest in those of the secondary branches, seeds at higher nodal positions on the main stem contained more 14C. The amount of 14C in seeds of the primary branches decreased with an increase in nodal position from the main stem. Distribution of 14C assimilates into the seeds of plants subjected to water deficit was reduced at all stages of growth. The resultant decrease in assimilate distribution to seeds will lead to a reduction in yield of soybean grown under conditions of water deficit. JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 1 Number 3, July (1999) pp. 66-72

Extraction of Australian ginger root with carbon dioxide and ethanol entrainer

Ginger oil, containing both essential oil and oleoresin components, was obtained from the dried roots of crushed Australian-grown ginger by extraction with liquid and supercritical carbon dioxide containing up to 2% w/w ethanol as co-solvent. Temperatures ranged from 9 to 35°C, pressures 6 to 10 MPa and mass velocity of CO 2 in the extractor from 0.17 to 0.46 kg m −2 s −1. Particle size averaged 250 μm. The proportions of essential oil and oleoresins in the extract depended on extraction conditions. The recovery of oleoresin was greater with entrainer, high solvent/feed ratio and higher pressure, but showed little variation with temperature over the range studied. Extraction curves revealed three distinct stages of mass transfer control, a characteristic not previously reported. The rate of extraction in the first stage was highest, linear and lasted for typically 35% of total oil yield. The second stage was also linear but at a reduced rate. The third stage showed typical diffusion-controlled characteristics. Gas chromatographic analyses revealed that later fractions of extract contained a higher proportion of oleoresin components. The refractive index of the extracts increased with solvent/feed ratio, as extract colour changed from straw yellow to dark orange/brown. The results demonstrated the variety of flavour extracts that could be produced under different extraction conditions and that the use of ethanol co-solvent maintained recoveries at pressures lower than those required with pure carbon dioxide.

Influence of particle grain size on the yield and composition of products from the pyrolysis of oil shales

Oil shales from two regions of Pakistan have been pyrolysed in a fixed bed reactor in relation to particle grain size. Five size ranges were investigated, <0.5, 0.5–1.0, 1.0–1.7, 1.7–2.8 and 6.0–10 mm. The pyrolysis system consisted of a 200 cm 3 stainless steel fixed bed reactor externally electrically heated. The samples were heated to 520°C at 10 K min −1 and the oil shale sample was continuously purged with nitrogen to remove the pyrolysis products from the reactor and to minimise secondary reactions. The gases were analysed for their content of CO, CO 2, H 2, CH 4 and other hydrocarbons up to C 4. The derived pyrolysis oil was condensed in a series of cold traps and the total oil yield determined. In addition, experiments were carried out on a thermogravimetric analyser using the three smallest particle grain sizes under identical heating conditions to the fixed bed reactor. It was found that increasing the particle size up to the largest size used of 10 mm resulted in an increase in oil yield. The total gaseous yield was decreased, reflecting a decrease in concentration for H 2, CO, CO 2 and the majority of the hydrocarbon gases. The raw oil shale samples of various particle size ranges were analysed to determine the elemental composition and surface area to determine their influence on the compositional changes in oil and gaseous yield with particle size range.

Effects of added transition metals and two-stage heating on reactions of sodium-aluminate-treated coals in water with CO, H 2 and COH 2 mixtures

A small suite of well-characterized Australian and N. American coals ranging in rank from brown to high-volatile bituminous and in H/C atomic ratio from 0.73 to 1 was reacted at 365 and 400°C with CO, H 2 and CO-H 2 mixtures in water. The effect of acid-washing was negligible, except for one coal of high Mg and Ca content. Impregnation of the coals with sodium aluminate (NaAlO 2) and Fe, Co, Ni, Cu and Ni-Mo led to modest increases in conversion compared with coals impregnated with NaAlO 2 alone for reaction at 365°C. Impregnation with Sn gave no increase in conversion. Greater effects were observed on addition of transition metals for reaction at 400°C. Nickel and nickel molybdenum were the most effective additives. There were no consistent effects of coal rank or H/C atomic ratio. Reactions in which the alkali and transition metals were added as the carbonylates NaHFe(CO) 4 and NaCo(CO) 4 gave similar results to those obtained by the impregnation method of catalyst addition. Reactions with two-stage heating (first stage 365°C; second stage 400°C) using CO or CO-H 2 gave little benefit for brown (Loy Yang) and subbituminous (Taiheiyo) coals but modest increases in conversion and asphaltene yields for high-volatile bituminous (Surat Basin) coal. However, two-stage reactions of Loy Yang brown coal with CO-H 2O-NaAlO 2 in which CO was recharged before the second stage (first stage 330, 365 or 400°C; second stage 400°C) gave large increases in both total conversion and oil yield compared with reactions for the same duration at 400°C with only a single charge of CO.

Yield improvement in the regenerated and transplanted mint Mentha arvensis by recycling the organic wastes and manures

Field experiments were carried out during winter-summer seasons of 1994 and 1995 at Lucknow, India, located at 26·5°N, 80·5°E and 120 m above mean sea level to study the effects of (i) organic wastes and/or manures on the regenerated and transplanted mint crops and (ii) rescheduling of the harvest time in the sucker-planted crop. The treatments studied were of citronella ( Cymbopogon winterianus) distillation waste and pea ( Pisum sativum) straw mulches at 7 t ha −1, farmyard manure (FYM) at 20 t ha −1 at planting, FYM at 20 t ha −1 after the first harvest and a control (no application of mulch and FYM), supplementary to the inorganic N fertilisation at 0, 80, 160 and 240 kg N ha −1. The harvesting times investigated in the sucker-planted crop were 90, 100, 110 and 120 days after planting. The use of citronella distillation waste as mulch and FYM were most effective in enhancing the total herb and essential oil yields (planted + regenerated harvests) when the planted crop was harvested at 110 days after planting. The yield of regenerated crop improved significantly in the plots that had received citronella mulch or FYM during the planted-crop period, as compared with that of the control; citronella-waste mulch treatment proved better than FYM treatment. Application of 160 kg N ha −1 in the form of inorganic fertiliser and citronella distillation waste mulch at 7 t ha −1 met the N requirements of the transplanted mint crop. Mulch applications improved the efficiency of utilisation of inorganic N by about 10%. Application of mulch had no effect on the quality of the oil obtained in the first harvest of the sucker-planted crop and in the transplanted crop. It is recommended that under subtropical conditions, citronella distillation waste mulch should be applied after the sprouting of suckers during the planted crop period to obtain higher yields of herb and essential oil from the planted as well as the regenerated crop harvests. In order to get the maximum yield advantages from both the harvests, the planted crop should be harvested at 110 days after planting. The use of citronella-waste mulch with 160 kg N ha −1 minimised the cost of transplanted mint production by a factor equivalent to one third.

The Production and Economic Potential of Cropping Sequences with Medicinal and Aromatic Crops in a Subtropical Environment

A field experiment at the Central Institute of Medicinal and Aromatic Plants, Lucknow, India, studied the economic feasibility of 8 medicinal and aromatic plants cropping sequences using rice (Oryza sativa), potato (Solarium tuberosum), mint (Mentha arvensis), coriander (Coriandrum sativum), mustard (Brassica compestris var. Toria), garlic (Allium sativum), chamomile (Matricaria chamomilla), onion (Allium cepa), and wheat (Triticum aestivum). The inclusion of a medicinal, aromatic, and vegetable crop during the winter season greatly increased the economic return from a unit area. The rice, garlic, and mint; rice, potato, onion, and mint; and a rice, chamomile, and mint cropping sequences increased the total equivalent yield of oil by 276.3, 284.8, and 230 percent, respectively, as compared with a rice and wheat cropping sequence. The rice, garlic, and mint cropping sequence increased net return, production efficiency, and benefit as compared with other cropping sequences.