FOXGLOVE ( Digitals lanata Enrh ). An exotic biennial herb, cultivated mainly in central and southern Europe for leaves which contain glycosides used for heart stimulation. India imports a major parts of its requirements of this drugs. The crop perfers silty-loam to clayey-loam soils, rich in organic matter and temperate climate ( 1200-2000 m above the sea-level ). The seed-rate used is 500 grammes per hectare. The nursery is raised in early spring and seedlings, when 8-10 weeks old, are transplanted, 30x45 cm to 60x60 cm apart, depending upon the soil fertility . It is an irrigated crop and makes only a moderate demand for nutrients, mainly as nitrogenous and phosphatic fertilzers. The plants flower in the second year, but the flowering stalks are removed to induce a larger leafy growth . In general, one harvest of the leaf crop is obtained in October in the first year, whereas 3 harvests of leaf crop are obtained in the second year. The average yield recorded in India in the second year is 600 kg/hs ; higher yield up to 1,500 kg are reported from elsewhere. Digitalis leaves are thermolabile and hygroscopic and therefore, should be rapidly dried at 40 C immediately after collection. They should contain 0.1% glycoside ( digoxin , digitoxin, gitoxin , etc. ) calculated as lanatocide-c and not more than 5% moisture. The leaves could be stored in the form of coarse powder in airtight containers placed in a cool and a dry place.

DILL OR SOWA( Anethum graveolens Linn. ). Sowa is a rabi crop grown alomost throughout the country for its fresh aromatic leaves used in cooking, and its fruits are marketed as a common condiment. The fruits contain an essential oil, rich in carvone and is used in pharmacy for the preperation of dill water and similar preperations to treat flatulence, abdominal and colic pain. India exports dill fruits worth about Rs 2 million annually. There are two known varieties, viz. the East Indian Dill ( A. graveolens var. sowa ) and European Dill ( A. graveolens Linn.) ; the former alone is cultivated in India commercially; its oil possesses superior aroma, but is considered inferior in pharmacy owing to the presence of a toxic substance (dillapiole) which is, however, easily removed.

Dill prefers well-drained fertile loamy soil and can be raised under a wide range of climatic conditions. The seeds are sown direct in the fields in rows or along the bunds in early autumn and the seedlings are thinned after about 40 days of sowing to maintain a spacing of 60 x30 cm. The crop is given 40kg each of N, P and K per ha at planting and another 40kg of N as top-dressing, depending upon the fertility status of the field. The crop mature by the end of April in nothern India and green mature umbnles ar e picked in 10-25 days to avoid seed-shattering. The average yield comes to 1 tonne of furits per ha. The sowa seeds on distillation yield 2.5 to 3 per cent of an essential oil rich in arvone which imparts to the oil its characteristic flavour.

Powdery mildew (Erysiphe umbelliferum forma anethi ) sometimes casuses heavy damage to the crop and is controlled by 2 to 3 sprayings of sulphur at 25 kg/ha during the early flowering stage. Aphids ocassionally cause damage; the spraying of Malathion (0.5%) 2 to 3 times during infection is recommended.

LIQUORICE OR MULHATI (Glycyrrhiza glabra Linn.). Liquorice is a hardy perennial legume, about 0.6 m tall,found wild in countries of west Asia. Its dried peeled or unpeeled underground stems and roots constitute the drug. It is demucent , mildlu laxative, expectorant and, as such, is an important constituent of all cough and catarrh syrups, throat lozenges and pastilles ; its extract containing glycyrrhizin (2.14%) has a healing effect on peptic ulcers. Large quantities of liquorice root is used in confectionery and tobacco-blending. There are a number of commercial cultivation varities of liquorice, such as typica Regal and Herd. (Spanish liquorice ) which is the sweetest of all and therefore, fetches higher price; var. glandulifera Waldst and Kit. (Russian liquorice) is richer in glycyrrhizin but the sweet taste is accompanied with perceptible but mild, bitterness owing to the presence of liquiritin and isoliquritin; var. violaca Boiss. ( Persian liquorice ) produces thich, hard and lumpy roots and is considered inferior in quality.

Liquorice grows well in fertile sandy-loamy soils in a warm and dry climate, having a long growing season marked with well-defined winters to induce the translocation of food to the underground perennating rhizomes. Heavy rain or frost affects its growth adversely. Most of the growing areas fall around 14N latitude. The crop is raised from rooted cuttings which are planted in carly spring 90 x 60 cm apart in rows. The beds are worked up to a depth of 1 metre and liberally manured. Seeds are seldom used. Var. typically produces a strong taproot which gives out rhizomes, whereas var. glandulifera sends out rhizomes are ready for harvesting in 3 to 4 years and are dug out in autumn after rains. A portion of the harvested material is decorticated before drying to produce the peeled liquorice of commerce. The material is cut into pieces, 15-20 cm long and 1 to 2 cm in diameter, and are dried alternatelly in shade and the sun. This drying reduces the weight of the material to 50 per cent. Artifical drying can also be done at 30-40 C. The crop yield ranges fron 1 to 3 tonnes per hectare, depending upon the soil fertility, the variety, the climate and cultivation practices.

DIOSCOREA. The tubers of a number of non-edible dioecious species of Diocorea provide raw material for the industrial production of corticosteroids is around 300 tonnes, valued at about Rs 3,000 million. Of the several species, D. composita Hemsl, and D. floribunda Mart. and Gal. (from Central America ) and D. deltoidea Wall. ex Kunth. ( from western Himalayas ) and D. prazeri Prain and Burk. ( from Eastern Himalayas ) stand out prominently because of the higher percentage of diogenin content in their tubers. Of late, a D. floribunda clone, developed at the Indian Institute of Horticultural Research, Bangalore, has been found to grow fast and give exploitable tuber yield in about 18 months of the growing period.

The crop of Discorea floribunda is raised from tuber pieces, each weighing 50-70 grammes, treated with a stemic fungicide for protection against soft-rot; these tuber pieces are planted in pits at 60 x45 cm spacing during March- April . The tubers sprout between 30 and 60 days after planting. Each pit is given 1.5kg of farmyard manure or compost along with 30 kg each of N and P per ha at planting, suplemented with similar quantities of fertilizers during the rainy season. Another application of 60 kg of N+40kg of P is given in 2 split doses in the second year. The growing vines are given support for getting the optimum uy\yield . The tubers grow up to 30 cm depth in the soil and , being soft, should be dug out carefully. An average yield of 1 kg of fresh turbers, containing 70 per cent moisture, per plant is reported from Bangalore. The calculated tuber yield as reported, is 7.5 tonnes (dry) per ha, containing, on an average, 3 per cent diogenin.

The aromatic plants possess odoriferous and volatile substances which occur as essential oils, gum exudate, balsam and oleo-resin in one or more parts, viz. root, wood, bark, foliage, flower and fruit. The chemical nature of these aromatic substances may be due to a variety of complex the chemical compounds. Many of these aromatics are powerful germicides and have anti-bacterial properties, but the bulk of the produce finds use in perfunery and the food-flavouring industries. Amongst the two, the per-fumeru and allied industries consume much larger amounts of the natural fragrant material. According to the UN Word Statistics (1972), the annual world trade (excluding countries in eastern Europe ) in essential oils and perfummery aromatics for 1969 was of the order of Rs 2250 million; also, a large quantity of the aromatic material of plant orgin is utilized in cosmetics, toiletries and allied industries. Our current volume of foreign trade in the perfumery material, essential oils and aromatic compounds is around Rs 65 million and this amount accounts for 1.6 per cent of the world trade. Some sixty-two types of essential oils come to the international market with a large and consistent demand. However, our treatement of the aromatic plants is confined to a few more important essential-oil crops grown in the country.

The methods employed to obtain aromatic substances from plants are classifed into distillation, enfleurage, maceration, expression and solvent extraction. Expect in the case of flowers crops, such as jasmine and kewara in which the fragrant constituents are likely to be decomposed or destroyed, the essential oils are mostly obtained by distilling the produce; in fact, steam distillation is the oldest method of separation of essential oils. The perfumery material is filled in a large-galvanizediron still over a perforated netal grid. Water is filled in the still below the level of the grid so that it generates a low-pressure steam on heating to pass through the material. The water vapours carry with it the essential oil of the perfumery material. These vapours are passed through a condenser and collected in a vessel where the oil is ecanted with a seperating-funnel.

A simple field distillation unit could be fabricated by a skilled blacksmith. For more efficient and quick distillation of the produce; " steam distillation" units are employed. These units are built on the same principle except that live steam at 40-100 1b pressure per inch is injected into the filling-still through perforated coils and the distillation is completed in a shorter period. It has the advantages of handeling a larger quantity of the material, besides improving upon the recovery of the essential oil.

As stated earlier, the solvent-extraction method is employed for the extractors are of two types, viz.stationary and rotatory types, and low-bowiling solvents, like petroleum either, alcohol or benzen, are used for extracting the odoriferous principles. The stationary type extractors consists of vertical cylinders provided with type extractors consists of vertical cylinders provided with perforated metal grids arranged horizontally around a central vertical shaft. The flower crop is charged over the grids which come into constant with the solvent periodically and the essential oil is removed in successive washings. The rotatory type consists of an iron drum which rotates on a horizontal axis. The interior of the drum is divided with a perforated metal partition of holding floers and the solvent is filled in the lower part of the extractor. While the drum moves, the solvent seeps through the perforations and drips back, so that the essential oil is washed out to the solvent. This extract is than distilled in a vacuum still at a low temperature to recover the disolvant. The floral concentrate, thus obtained, also contains some waxes and plant pigments which are removed by treating with warm alcohol. The filtered solution, so obtained, is either used as such, or is concentrated in vaccum into a viscous oil.

LEMON GRASS ( Cymbopogon flexuosus Stapf.). It is a stemless perennial grass, found wild in the southern states of India. The leaves yield an aromatic oil, containing 75-85 per cent citral. The oil is used in soaps, cosmetics and disinfectants and is a raw material for manufacturing ions and vitamin A. The crop is grown on about 390,000 ha in Kerals and about 90 per cent of the produce is exported, earning about Rs 10 million in foreign exchange annually.

The crop is grown mainly as a rain-fed crop on poor marginal lands. It is a hardy drought-resistant plant and is grown under a wided range of climatic conditions. Two types are recognized : (1) the red-stemmed grass is the true lemon-grass and a selection ' OD-19' made at the Lemon Grass Research Station, Oodakkali (Kerala) is recommended for high yield, (2) the white-stemmed (var.albscens) yields oil or low citral content. The crop is best propagated through seed raised in nurseries ; 10kg of the seed produces enough seedlings for planting a hectare. About 2-month-old seedlings are planted in rows, 40 to 15x 10 cm apart, during rains and the first harvest is ready after 90 days . In Kerala, 3 harvests are obtained in the first year and 4 to 5 harvests during each of the 3 to 5 succeeding years; the crop is cut after every 60 to 65 days, except during the dry season. The fields are manured librally with ash and spent grass ( obtained after the distillation of the oil ) ; farmers seldom apply inorganic fertilizers. The herbage contains 0.35% oil on fresh-weight basis. The grass yield ranges from 18 to 25 tonnes per hectare, giving 60 - 72 kg of oil.

CITRONELLA GRASS (Cymobopogon winteriaruns Jowitt ). It is a stemless perennial grass. The oil is mainly used in soaps, Cosmetics, deodorants and mosquito-repellent creams. It is a recent introduction into India and its cultivation. mainly in the lower hills of Assam, in Karnataka and southern Gujrat, covers about 2,000 hectares. A part of out requirement is still met by imports,

Java citronella is grown up to 1,000 m above sea level on well-drained sandy-loanto clayey-loamy soils with pH varying from 5 to 7.5 As a rainfed crop, it is propagated by using rooted slips, and is planted during the rainy season in rows, 60 to 45 cm x 45 to 30 cm apart, depending on the rate of growth and the soil fetility. Usually, the leafy portion is removed at planting during the monsoon season and the plants begin to tiller in 30 days after planting. A healthy one-year -old clump yields 60 to 80 slips. The crop needs a large quantity of nitrogenous fertilizers , When grown on medium soils, it is given 60 kg of P, 40 kg of K and 20 kg of N per ha at planting, supplemented with 80 to 100 kg of N per hectare annually as top-dressing in 3 to 4 split doses. The crop is irrigated after every 10-15 days during the dry season and the first harvest is count 20 cm above the ground after 90 days of planting; usually 3 cuttings are obtained annually ( 4 under Assam conditions ) for 3 to 5 year after planting.