Botanical Name: Musa textiles Nees.
Family: Musaceae.
Vernacular: English-Manila Hemp, Abaca; Tamil & Malayalam- Naaru, Vazhai;
Kannada-Nati bale.
Abaca fibre or Manila hemp is obtained from the sheathing leaf bases of Musa textilis. The plant is a member of the section Australimusa of the banana family, the Musaceae. It is the strongest of the structural fibres and, because it does not deteriorate or rot in fresh or salt water, and is elastic, light and durable, it is used mostly for the manufacture of ship’s cables and ropes, for strong sacking, coarse fabrics and strong paper.
The wild bananas are all diploid and are distributed in south-east Asia and the Pacific. It has chromosome number of 2n=2x=20. The plant is native to and cultivated in the Philippine Islands and Borneo.
Manila hemp is a tall, stout, stoloniferous plant, 2.5-4.0 m high; Leaves broadly oblong, leathery, firm in texture, bright green above, glaucous beneath, often with large brown spots: fruits compact, nearly terete, 5-7 cm. diam., with pale cream coloured inedible pulp filled with many seeds. This species is valued for its fibre extracted from leaf sheaths of mature plants.
The plant was introduced and experimentally tried in India for its fibre. Experimental cultivation of M.
textiles has been tried in West Bengal, Tamil Nadu and Andaman Islands. The plant has been reported to thrive well in Andaman, but little attention seems to have been paid to cultivation and fibre extraction.The plant thrives in well-drained, moderately rich loams at elevations of 60-150 cm. with an annual average rainfall of 250- 275 cm., evenly distributed throughout the year.
The plant is propagated by suckers or from parts of mature rootstock containing one or more growing buds.
The largest producer of abaca in the world is Indonesia and some countries of Central America also produce abaca fibre in small quantities.
Fibre
The harvested stalks of the plant are utilized for the extraction of fibre. The fibre is located primarily adjacent to the outer surface of the leaf sheath. Each leaf sheath consists in cross-section of 3 layers, the outer fibrous layer, the middle containing a small quantity of fine white fibre, and the inner layer, which contains no fibre at all.
The fibre consists of strands ranging in length from 0.9-2.7 m. Each strand is made up of bundles of fibre cells irregularly round or oval with tapering ends and with long distinct lumens. The fibre is strong and flexible. It is highly resistant to microbial rotting and to salt water.
Uses
The fibre is used mainly for twines, ropes and cable. It is much valued for hawkers, ship’s cables and riggings. It is also used in the manufacture of tough paper.
Diseases
Abaca plant is susceptible to bunchy top, mosaic, wilt diseases and insect pests like the banana borer.
HEMP
Botanical Name: Cannabis sativa Linn.
Family:Cannabinaceae
Vernacular: Sanskrit-Bhanga, Vijaya; Hindi, Bengali and Gujarati- Bhang, Ganja, Charas, Siddhi, Jia;
Telugu-Ganzai,kapam-chettu; Tamil-Ganja, Bjangi; Kannada-Bhangi; English-True Hemp, Soft Hemp.
Hemp is an ancient crop plant, which provides a fibre, a psychotomimetic drug, minor food and a fixed oil from the seeds. The plant is considered to be a native of western and central Asia. It is practically naturalized in the sub-Himalayan tract in India, and is abundantly met with in wastelands from Punjab eastwards to Bengal and Bihar and extending southwards to Deccan.
Hemp is tall annual herb; 1.2-4.8 m high with erect angular stem, bearing palmately divided leaves. The plant is dioecious or rarely monoecious. Flowers, greenish, male flowers borne in long drooping panicles and female flowers in short axillary spikes; fruit is an ovate seed-like achene.
The plant is cultivated commercially for its fibre mostly in Europe and parts of China, Japan and USA. In India, the cultivation of the hemp plant is permitted in the districts of Almora, Garhawal and Nainital in Uttar Pradesh for its fibre but not for the production of hemp drugs. The plant is also cultivated to a small extent in Kashmir, Nepal and Travancore.
For obtaining fibre the plant is grown on rich loamy soil in a mild humid climate, with a temperature range of 15- 26oC during the growing season. The land is well prepared and liberally manured. The seeds are sown either broadcast or by drills.
The crop is harvested as soon as the lower leaves are shed and the tops of stalks and flowers turn yellow. Harvesting at the time the plants are about to flower gives the optimum yield of high quality fibre.
Extraction of Fibre
The fibre is extracted from stalks, either by water-retting or dew-retting. The latter method is common is Europe and America, while in Italy, and in some parts of Russia, Hungary, Yugoslavia and in India, water retting is the common practice. The stalks are tied in bundles and immerse in ponds or slow-running streams until the bark including the fibre, separates out from the woody inner portion. The duration of retting varies in different localities depending upon the temperature of water. In hot and damp weather, 3-4 days may be sufficient. In cool and dry weather 1-2 weeks are required. Dew-retted fibre is grey; while water-retted hemp is usually cream-white.
Hemp Fibre
Hemp fibre is the bast fibre obtained from primary and secondary phloem fibres. Secondary phloem fibres are smaller, shorter, thin walled or more brittle than the primary phloem fibres. The fibres from staminate plants are considered to be superior to that of pistillate plants. Hemp fibre is strong, lustrous and durable.
Commercial fibre is 100-200 cm. in length. Its fineness of staple is less than that of linen, though its tensile strength is appreciably greater.
Under the microscope the fibre is seen to consist of cell elements, which are unusually long averaging about 2cm. In length, and 22 microns in diameter. The fibre ends are bluntly rounded. The fibre is
somewhat uneven in diameter and exhibits frequent joints, longitudinal fractures and swollen fissures. It is made up of a mixture of cellulose and ligno-cellulose.
Uses
Hemp is used for the manufacture of fine cordage, twine, sailcloth, tarpaulins and carpet yarns. Loose fibre is used for caulking boats, pumps, engines and other machinery. During the last war, green fibre prepared without retting by a process of decorticating and cottonising, was used as a substitute for jute in making binder-twine and sacks. The use of hemp in cordages, twines and ropes has declined, its place being taken by the hard fibres. Manila and sisal. Hemp stems can be used for the manufacture of coarse paper.