Artemisia pallens

Artemisia pallens Wall. ex DC. is a small, herbaceous, aromatic plant with an exquisite aroma. It is grown in southern parts of India particularly in the states of Karnataka, Tamil Nadu and Andhra Pradesh. It is apparently native to this area in south India. However, it is not found growing wild in this area probably because its seeds are very small and the seedlings are very delicate and need to be nurtured with extreme care until they are at least one month old. Artemisia pallens is locally known as davana and its essential oil is known as davana oil all over the world. Artemisia pallens is, therefore, referred to as davana in this chapter.

Davana has been traditionally cultivated sporadically in gardens in south India for its delicately fragrant leaves and flower heads which are used in garlands, chaplets and religious offerings; it has been cultivated only recently for its essential oil. The fragrance of the herb and its oil is described as exquisite, deep, mellow, persistent and characteristically fruity. The cultivation of this plant on a commercial scale began only in the late 1960’s after its oil caught the fancy of perfumers in the USA and Europe. Commercial quantities of davana oil on a large scale were, however, not produced until 1970. For last 10 years, davana oil has been regularly exported from India, although not in very large quantities, to the USA, France, Germany, Japan, the Netherlands and many other countries. The latest figures show that the amount exported in 1998-1999 was much greater (4,060 kg) with a value of Rs 89 million. Following the recognition of the economic value of its essential oil, interest and research into various aspects of davana has increased.

Artemisia pallens: Botany

The botanical description of davana, as given by Narayana et al. (), is as follows: Davana is an annual, erect, branched, aromatic herb, 40-60 cm high and covered with greyish-white tomentose. Leaves are bluish-green in colour, alternate, exstipulate, petiolate, lobed to pinnatisect and covered with greyish-white tomentose. Capitula are peduncled to sessile, axillary or forming lax racemes, simple, heterogamous with yellow florets. Involucre, two or more seriate, with ovate to elliptic-linear, alternating entire bracts, grey-tomentose outside, glabrous and green inside. Outer florets glabrous except for a few cottony hairs, tubular, generally three-lobed, female without pappus; stigma generally two-lobed, rarely three-lobed. Inner florets also glabrous except for a few cottony hairs, tubular, five-lobbed, bisexual; stamens five with free epipetalous filaments and dithecous, introse, syngenesious anthers; pollen sacs prolonged, tapering; style bifid.

Agronomy (Including Distillation for Essential Oil)

Davana oil is reported to have been first distilled on an experimental scale from the herb grown near Mysore, as early as in 1921, at the Government Soap Factory, Bangalore. The commercial distillation and export of davana oil was first taken up at about the same time by Mr. M. Sundara Rao, at M/s. Essenfleur Products Ltd., Mysore, from the davana herb grown in his estate at Hemmanahalli, near Mysore. However, according to another report, davana oil was first distilled and exported to Europe by Mr. Mavalankar, an Indian perfumer. The report also mentioned that the oil was distilled and exported by The East Indian Sandal Oil Distilleries (Private) Ltd., Kuppam (S. India).

Although Sastry, (1946) Guenther, (1952) and Ranganathan, (1963) briefly described the cultivation and distillation of davana, a detailed account was first given by Gowda and Ramaswamy (1965). Subsequently, Gulati et al. (1967) gave a similar account of cultivation and distillation of davana in the Tarai region in north India. However, the quality of davana oil from this area was not comparable with the quality of oil produced in south India. A. farm bulletin describing the cultivation of davana and distillation of its oil was published in 1978 and, subsequently, revised in 1990. The above reports appear to be based largely on empirical observations and experience rather than based on data obtained from specifically designed and systematically conducted experiments. A. sudden increase in the interest in medicinal and aromatic plants and a preference for plant based rather than synthetic products all over the world during the last decade has resulted in increased scientific activity in this area and davana has also received increased attention. Different agronomic parameters including fertilizer requirement, optimum planting density, planting season etc. for maximizing productivity of davana have been investigated. The effect of plant growth regulators like gibberellic acid, cycocel and TIBA (Tri-iodo-benzoic acid), which have been successfully used to increase the yields of several horticultural plants were also studied for their effects on the herb and oil yield of davana; however they were found to be ineffective.

The agronomic practices for davana are summarized as follows after taking into consideration all the published information cited above.

Soil and Season

Davana is cultivated in a very small restricted geographic area in south India. It does not withstand heavy rains and water logging. It grows well in red loamy soils with good drainage and organic matter. The crop can be grown almost throughout the year for ornamental purposes. However, for cultivation of this crop for its essential oil, the season is very important and late October to early November sown crops have been found to give maximum oil yield. Light showers, mild winters with heavy morning dew and no frost in the beginning of the season, and warm and dry weather towards harvest time are believed to contribute to higher oil yields and better quality oil.

Nursery Preparation

Fresh seed obtained from the previous crop should preferably be used as davana seeds are known to lose their viability very quickly. About 1.5 kg of seeds and an area of 500 m2 are required for raising seedlings sufficient for planting an area of one hectare. As the seeds are very small, they are mixed with about 10 kg of fine sand before sowing and are sown by broadcasting the mixture in well prepared nursery beds of generally 3 m2 size. Seeds germinate in three to four days and during this period nursery beds are hand-watered lightly, twice a day. Subsequently, nursery beds are lightly surface irrigated every day. The seedlings reach the transplanting stage after about five weeks.

Fertilizer Requirement

It is difficult to assess the fertilizer requirement from the available literature. The maximum response has been obtained with 100 – 150 kg N per hectare for the main crop and 75 kg for the ratoon crop applied at monthly intervals, in three and two equal splits for the main and ratoon crops, respectively; (the ratoon crop is that grown from the stalks remaining after harvest of the main crop). Six tonnes of farmyard manure, and 40 kg each of P and K per hectare are incorporated into the soil at the time of land preparation.

Transplanting and Irrigation

Five week old seedlings are transplanted in the field at a spacing of 15 x 7.5 cm2; spacing wider than 30 x 15 cm2 have been found to give lower oil yields. The crop is irrigated lightly, every day for about 10 days after transplanting and twice a week subsequently.

Harvesting

Harvesting is done when the crop is in full bloom. This stage is generally reached by the end of February or by first week of March i.e., about 10 weeks after transplanting. The crop is harvested at a height of about five to six cm above the ground level; the ratoon crop comes to harvest about two months later. The main and ratoon crops together yield about 10-15 tonnes of herbage and about 7.5-10 kg of oil per hectare.

Distillation

Davana herbage is either dried in shade for two to three days or for not more than 12 hours in bright sunshine before distillation. The herb is then steam distilled at a pressure of about 1.0-2.0 kg/cm2 for about 10-15 hours; the bulk of the oil is, however, distilled in about 8 hours. The recovery of the oil from the semi-dried herbage is generally about 0.2%. The oil is then filtered, dried with anhydrous sodium sulphate and stored in aluminium containers.

Quality Aspects

Davana oil is produced in three states in south India. The oil produced in states of Karnataka and Andhra Pradesh is, however, usually preferred to the oil produced in southern parts of Tamil Nadu, as the latter is considered to be inferior in odour value. As davana oil is an expensive oil, there is a possibility of adulteration of the oil with cheaper and undesirable materials like vegetable or fixed oils. This will drastically affect the quality of the oil as well as its trade. It is therefore necessary to formulate standards for davana oil with respect to its physicochemical characteristics and chemical constituents in order to exercise quality control.

Medicinal Properties and Uses

Antipyretic and anthelmintic properties have been attributed to davana. Recently, Subramoniam et al. () found that the methanol extract of davana significantly reduced blood glucose levels in glucose-fed hyperglycaemic and alloxan-induced diabetic rats. The water extract was, however, inactive.

The essential oil of davana, like many other essential oils, has been found to exhibit antifungal and antibacterial properties. The dried herb of davana is used as a moth repellant in the preservation of delicate and expensive fabrics.

The fresh herb of davana has been traditionally used as a component of garlands and bouquets, to lend an element of freshness. This property of davana may find application in aromatherapy which, although known since ancient times, in India, China, Egypt and Babylonia, is now becoming increasingly popular.

Davana oil is, however, mainly used in fine and expensive perfumes. It is also extensively used in flavouring cakes, pastries, tobacco and alcoholic beverages.

Some Areas for Future Work

Davana has been actively studied only since 1980. Therefore, there is considerable scope for further work on all aspects of this plant. However, following are some areas which probably need immediate attention.

1. Very little breeding work has been done on the development of high oil yielding varieties. Therefore, there is considerable scope for increasing the oil yield of davana through breeding.

2. The quality of davana oil is known to be influenced by environmental conditions during crop growth and during drying of the herb before distillation. Systematic studies under controlled environmental conditions are, therefore, necessary to define optimum environmental conditions for obtaining good quality davana oil.

3. Considerable variation is evident in the physico-chemical properties of davana oil reported by various workers. Also, as there is a possibility for adulteration of davana oil there is an urgent need to formulate standards for davana oil for exercising quality control.

4. The demand/supply of davana oil has been found to fluctuate widely over years. This is reflected in export statistics on davana oil. Market research is, therefore, another very important area which requires immediate attention.

R.N. Kulkarni

Selections from the book: “Artemisia”. Edited by Colin W. Wright. Series: “Medicinal and Aromatic Plants — Industrial Profiles”. 2002.