Published in “The Hindu… in Science and TechnologyPage” on 15-10-1996
AGAVE is a large genus of short-stemmed half-woody plants bearing a rosette of long, erect, pointed, fleshy leaves. About 275 species of the Agavaceae family are distributed in tropical South America. Six species Agave anguistifolia, A. americana. A. hurida A. camtala, A. sisalana, and A. vera-cruz were introduced in India during the 15th century by the Portuguese. These are now completely naturalised and cultivated in different parts of the country particularly in the dry zones. In south India they are called as Kathaalai (in Tamil), Kithanara, Kalpataru (in Telugu) and Rakas patta (in Hindi).
Cultivation of four varieties of Agav americana, A. cantala, A. sisalana and A. vera cruz has proved beneficial. The plant has locally been used as a medicine for a long time. Generally, it is grown as a live fence. Its widespread root system serves as a good soil binder and so it is also used to check soil erosion by planting across gullies and slopes.Farmers in the arid and semiarid regions South India comprising Tamil Nadu, Karnataka Andhra Pradesh, Maharashtra and Orrisa grow it for its medicinal properties and for its fibre (used in making ropes).
Farmers in the arid and semi-arid regions of south India comprising Tamil Nadu, Karnataka, Andhra Pradesh, Maharashtra and Orissa grow it for its medicinal properties and for its fibre (used in making ropes)
Their leaves contain an alkaloid called hecogenin. Its juice is considered to be a laxative, diuretic and emmenagogue. It is also used as a resolvent in syphilis, scrofula and cancer. Thin slices of the leaves are used as a good poultice. The leaves are heated, split and applied on painful spots in rheumatic patients to relieve pain. The plants can grow in poor, infertile soil and rocky terrains.
Agave Americana or American aloe has large silvery-grey leaves. They are thick, fleshy and covered with a thick cuticle and a coating of wax. The margins of the leaf are pricky and the leaf itself ends in a spiny pointed tip. After a long growth period, say 60 years (sometimes 100 years) the plant produces flowers and huge inflorescence held aloft a huge and robust flesh stalk.
A native of Mexico and Central America plants find a natural home in the dry and hot regions of the Deccan peninsula. The young flower head on cutting yields a large quantity of juice which on fermentation yields pulque, the national drink of Mexico. The distilled liquor (alcohol content 3-4 per cent) is known as mescal. The plant is used as fish poison, and the plants’ core is used as febrifuge in malaria. It is used as an antiseptic and also in ascites, venereal sores, and dysentery.
cantala a perennial stout scapigerous plant with short woody stem, is native to Mexico. Its leaves appear in rosettes forming a crown, which is recurved in the upper surface. It is remotely spinescently dentate with 1-2 cm long upwardly hooked spines and scaly stout scapes. It is grown as a hedge and thrives well on fairly good soil and in regions with rainfall of 100-250 cm. The leaves yield a fibre to 3-4.5 per cent of their weight, which is roughly about 6.4 tonnes/ha.
sisalana, is a perennial short-stemmed herb, is cultivated in many parts of India. Its stem, 37.5 cm thick, bears a dark green rosette. It has thick, fleshy, rigid 10-15 cm long leaves which are 10-15 cm wide at the broadest portion. It is generally without spines on the margins with yellow flowers.
vera-cruz, a stout perennial herb 30-45 cm tall, with woody simple stem has long, erect spinescently dentate leaves. It has flowers in terminal panicles.
The stem contains polyfructosans besides a number of simple sugars as minor constituents. The soft woody portion of the stem is cooked with tamarind and jaggery in some parts of South India. While small quantities of the stem may be safely consumed, ingestion of large amounts produces gastro-intestinal disorders. The leaves yield a fibre (cellulose 75 per cent, lignin 15 per cent) which is coarser and stronger than cantala fibre and is used in making ropes, cordage and mats.
A. angustifolia the dwarf Aloe, Seemakathaalai (in Tamil), Kantala (in Sanskrit) and Balurakkasi (in Telugu), is a perennial herb with a stout trunk, still leaves in a compact rosette and flowers in terminal panicles. It is used as an ornamental plant and is nownaturalised in outer Himalayas and other parts. It is grown as hedge in gardens and along railways lines and is very common throughout Purandhar (Maharashtra).
B. lurida is an almost trunkless shrub, with leaves which are 0.9 m long and 15 cm wide. This was also introduced for its fibre that is shorter and somewhat stiffer than the other agave fibres. Mature leaves can be harvested from 3-4-year-old plants and from the fifth year onwards regular harvesting of leaves can be done for extracting fibre.
People in Tiruchy and Dindigul instead of collecting the mature leaves from the lower sides of the plant, collect the central stem axis cone (consisting of 15 to 20 immature leaves) beat them and extract the fibre. This damages the plant which takes a long time to grow. Such practice has to be discouraged.
Retting and mechanical methods are used for fibre extraction. In the retting process, the leaves after harvesting are immersed in water for about a week. During this period the pithy matter adhering to fibres disintegrates due to bacterial action. The retted leaves are then beaten on stones to remove the remaining extraneous matter. The separated fibre is washed, dried in the sun and baled. In the mechanical process, the fibre is extracted by rasping the leaves with a raspador. Raspador is a rotating drum mounted on an axle having blunt blades, fitted obliquely about 10 cm apart on its periphery. The leaves are fed into the slit of the raspador and pulled out. By this method almost the entire extraneous matter is removed leaving only the fibre strand. The fibre is then soaked in water about 10 minutes to remove the remaining green pigments and beaten on stone, washed again and dried.
The dried fibre is combed with a special knife to remove the remains of pithy matter; combing also renders the fibre lustrous. In India, both methods of fibre extraction are practised, though retting is common.
In some states, cooperative societies and private units are engaged in the fibre supply. Some quantity is locally used for preparation of twines, ordinary ropes, bags, hats and nets. The sisal waste is used in the manufacture of a hard lustrous wax which is agood substitute for carnauba wax. Experiments carried out at the National Chemical Laboratory, Pune, have indicated that the yield of wax is 8-18 per cent of the waste materials depending on the quality of the waste.
In Andhra Pradesh. fibre is extracted using a manually operated device in which the leaves are bruised and the cuticle and internal sap are removed. The fibres are then cleared, dried and packed. The waste (pulp) obtained after processing is used as a manure. In Maharashtra, cantala fibre is extracted on a commercial scale by the retting process. Mechanically decorticated fibre is finer but less tensile than sisal. The fibre is used for ropes, mats, cordage, twines and nets. Cantala fibre is pure white in colour, whereas sisal is light yellow.
In India, sisal is cultivated in Andra Pradesh, Assam, West Bengal, Bihar, Orissa, Tamil Nadu, Maharashtra and Karnataka. Sisal grows well on dry, permeable sandy loam soils and is highly drought resistant. It is reported to thrive well in areas with low rainfall. The leaves are cut for fibre between the third and fourth year. The lowest leaves are cut close to the trunk. Each plant yields 250-300 leaves during the 7-8 years of its life time.
Farmers in Tiruchy. Dindigul, Salem and Dharmapuri of Tamil Nadu collect the agave leaves for fibre which are made into ropes and sold. Average annual production of sisal fibre in India is estimated at about 12,000 tonnes, whereas the total demand of agave is well over 50,000 tones. Annually, India imports agave worth Rs. 2.5 crores from Tanzania, Kenya and other countries. However, India exports sisal ropes and twines to Nepal and Fiji Islands.
Due to its many favorable characteristics, various government departments have taken up agave planting in field boundaries, reserved forests and in barren lands. Such planting serves to check soil erosion and provides alternative sources of Income to the local villagers. In Tamil Nadu, the Forest Department has a specific division called Agave Division at Coimbatore.
Agave propagation can be carried out either by bulbils or root suckers. The bulbils are collected between March and May every year (it varies from species to species). The collected bulbils are then planted in primary beds (size 10m x 1m) at an espacement of 5cm × 5cm. Flood watering is done once in three days for six months. Weeding is done twice a month. After six months (that is when the seedlings are 20-30 cm high) the seedlings are fit to be planted in secondary beds. Secondary bed sites are cleared of all growth and the weeds are uprooted. Disc ploughing is done upto a depth of 30cm. The site is then levelled and 10m x 10m beds are formed. Six-month old seedlings are planted at an espacement of 25cm x 25cm in the field.
Before planting the beds are flood watered. After planting flood watering should be done twice a week for one month. Thereafter flood watering should be done once a week. After three months, one lime dressing – dusting of lime powder over the beds is essential. This may be done before planting the bulbils in the primary beds as well as before planting the seedling in the secondary beds. This helps in preventing fungal attack. Instead of dusting calcium powder, calcium hydroxide solution also may be sprayed over the beds. Weeding should be done twice a month. DAP fertilizer may also be applied. After one year, the seedlings are ready for transplantation in the field.
Manoj Sarkar and Aruna Basu Sarcar; Deputy Conservators at Chennai, TN Forest Department;
