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Hibiscus cannabinus L.

Malvaceae
Kenaf, Bimli, Bimlipatum, Jute, Deccan hemp

Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.


  1. Uses
  2. Folk Medicine
  3. Chemistry
  4. Description
  5. Germplasm
  6. Distribution
  7. Ecology
  8. Cultivation
  9. Harvesting
  10. Yields and Economics
  11. Energy
  12. Biotic Factors
  13. References

Uses

Kenaf is cultivated for its bast fibers which resemble and substitute for jute fibers. Fiber strands, 1.5–3 m long, are used for rope, cordage, canvas, sacking, carpet backing, and fishing nets. It is cultivated secondarily for the seeds which contain about 20% oil, used for: salad, cooking, and lubricant oils. Oil is also used in the manufacture of soap, linoleum, paints and varnishes, and for illumination. In 1968, Florida used 600 ha growing kenaf for bean poles (Whitely, 1981). Recently the pulp has been used in paper-making. Leaves are used as a potherb. A concentrated food for cattle in the form of seed-cake comes from the residue after oil extraction. Africans use soot from the stems as a black pigment. They also use a piece of the stem as a base for drilling fire.

Folk Medicine

Reported to be anodyne, aperitif, aphrodisiac, fattening, purgative, and stomachic, kenaf is a folk remedy for bilious conditions, bruises, fever, and puerperium (Duke and Wain, 1981). Powdered leaves are applied to Guinea worms in Africa. Africans use peelings from the stems for anemia, fatigue, lassitude, etc. In Gambia, the leaf infusion is used for coughs. Ayurvedics use the leaves for dysentery and bilious, blood and throat disorders. Seeds are applied externally to aches and bruises. Medicinally, juice of the flowers with sugar and black pepper is used in biliousness with acidity. Seeds are considered aphrodisiac and fattening.

Chemistry

Seeds contain radium, thorium, and rubidium, and a fatty oil like arachis oil (Reed, 1976). Seeds also contain 9.6% moisture, 6.4% ash, 20.4% fatty oil, 21.4% nitrogenous matter, 15.7% saccharifiable matter, 12.9% crude fiber, and 13.9% other matter. The seed oil contains 45.3% oleic-, 23.4% linoleic- 14.0% palmitic-, and 6.0% stearic-acids. Dry press cake contains 33.0% protein, 6.0% oil, 17.4% crude fiber, 6.0% ash, and 37.6% N-free extract. The following amino acids have been identified in the acid hydrolysates of the proteins ALBUMIN (N, 15.38%) histidine, 2.57; arginine, 6.23; tyrosine, 1.80; lysine, 3.05; GLOBULIN-1 (N, 18.41%): histidine, 3.68; arginine, 13.60; tyrosine, 2.13; lysine, 2.63; GLOBULIN-2: histidine, 3.24; arginine, 12.16; tyrosine, 2.04; lysine, 1.95%. The cake, used as a fertilizer, contains: nitrogen, 5.25; phosphoric acid (P2O5), 0.95; and potash (K2O), 3.74%. Coloring matter of the flowers consists mostly of the glucoside cannabiscitrin (C21H20O13); with a small amount of the aglucone, cannabiscetin (C15H10O8), a flavonol identical with myricetin (C.S.I.R., 1948–1976). Fresh stems from India contain, (ZMB): 15.0% CP, 19.9% CF, 8.2% ash, 5.8% EE, 51.1% NFE, 2.08% Ca, and 0.5% P. Dried leaves, eaten in various countries, contain 13.1% CP, 11.6% CF, 11.8% ash, 2.1% EE, 61.4% NFE, 3.31% Ca, and 0.35% P (Gohl, 1981).

Description

Woody to herbaceous annual, mostly unbranched, fast-growing, with prickly stems, up to 4.2 m tall; leaves alternate, long-petiolate, shallowly to deeply parted, with 3–7 toothed lobes; flowers solitary, large to 10 cm in diameter, short-stalked, axillary, yellow with purple centers; sepals 5, petals 5; stamens numerous, connate; ovary superior; fruit a many-seeded, hairy capsule about 1 cm long; seeds brown, glabrous, wedge-shaped, 5 mm long, 3 mm wide, weight 25g/1000. Root a deep-penetrating taproot with deep-seated laterals (Reed, 1976).

Germplasm

Reported from the African and Hindustani Centers of Diversity, kenaf, or cvs thereof is reported to tolerate laterites, low pH, and some waterlogging or temporary inundations (Duke, 1978). Many cvs have been developed. Some are: simplex, viridis, Tuber, purpureus, and vulgaris. All trial crosses between the varieties have been successful. Diploid (2n = 36) and tetraploid (2n = 72) races have been found. Both self- and cross-pollination is found among the varieties (C.S.I.R., 1948–1976).

Distribution

Probably native to Africa, East Indies, Asia, or Australia, now naturalized in Africa and Asia, generally cultivated in India, and introduced in India, Indochina, Taiwan, Indonesia, and North and South America. Its distribution is between 45°N and 30°S.

Ecology

Ranging from Warm Temperate Thorn to Moist through Tropical Very Dry to Wet Forest Life Zones, kenaf is reported to tolerate annual precipitation of 5.7 to 41.0 dm (mean of 29 cases = 14.8), annual temperature of 11.1 to 27.5°C (mean of 29 cases = 21.1), and pH of 4.3 to 8.2 (mean of 24 cases = 6.1) (Duke, 1978, 1979). Kenaf is often recommended for tropical and subtropical climates, from sea-level to 1000 m altitude, with no night temperatures below 18.3°C, and 500 to 600 cm rainfall over 4–5 months with wet and dry periods. It is less exacting in its requirements than jute. It thrives best with temperatures of 15–27°C during the growing season. The plant is frost sensitive and damaged by heavy rains with strong winds. Kenaf is adaptable to a variety of soils, best being a deep, friable, well-drained, sandy loam with humus; light sandy soils are not recommended. A pH of neutral to slightly acid is suggested (C.S.I.R., 1948–1976). At higher latitudes the plant remains vegetative and does not flower until the daylength is less than 12.5 hr/day. Two weeks of very cloudy days will induce flowering as daylength approaches 12.5 hr. (Whitely, 1981).

Cultivation

Propagation is by seed. Seed retain viability for about 8 months under ordinary storage conditions. Soil preparation should be deep (at least 20 cm) and thorough. Seed is broadcast or planted with a grain drill in rows at the beginning of the rainy season, with about 6–30 kg seed/ha drilled 15 cm by 15 cm on dry soils or 12.5 cm by 12.5 cm on wet soils. Often two seeds are drilled and one seedling removed if germination has been good to insure an even stand for the production of uniform stalks. Planting depth is about 0.5–3.2 cm. Weeding for the first month is important. North of the equator planting is done in May or June, allowing as much time as possible for vegetative growth before flower set. Soils may be treated with manure or green-manure. Treatment with 585 kg/ha ammonium sulfate and green-manure of Mimosa envisa increases the yield of kenaf by 50%. One fertilizer recommendation is ca 35–70 kg/ha N, 40–60 kg/ha P2O5, and 45–65 kg/ha K2O. A kenaf crop of 50 MT green plants/ha withdraws from the soil about 175 kg N, 15 kg P, 75 kg K, 105 kg Ca, and 30 kg Mn (Whitely 1981). Almost any farmer living between 45°N and 30°S latitude, with a soil cabable of producing corn, cotton, sugar, beans, or vegetables can produce good crops of kenaf. Any of these crops may be used in rotation with kenaf. Rotation with green-manure crops is also recommended, as Crotalaria anagyroides, C. usaramoensis, or Mimosa envisa, which may be plowed under (Reed, l976).

Harvesting

Highest quality fiber is obtained when plants are harvested during the flowering period, usually in August north of the equator. Planting to harvest is from 90–125 days. Three reaping methods are used: hand-cut, machine-cut, and pulled by roots, as the lower stem contains the best fibers. Hand-cutting is practiced only where labor is cheap and plentiful. A water source is necessary at harvest time since retting from 5–22 days is required to separate the bark from the wood and release the fibers. The fibers are then cleaned by hand and dried in the sun. A skilled worker can strip and wash about 36–45 kg dry clean fiber per day. Equipment essential for growing and harvesting kenaf consists of a tractor, plow, harrow, light grain drill, and a decorticator. A small farmer can generally make money with the smallest hand-fed decorticator and 6 hectares. However, it is more profitable to plant a larger acreage and use a semi-automatic decorticator. Farmers in Cuba and the United States avoid expensive hand labor by utilizing a self-propelled harvester decorticator, which will produce 45 kg of dried fiber per working hour (Reed, 1976).

Yields and Economics

Yields of fibers in stems varies from 2–7%, and primarily depends on the fertility of the soil. Fiber yields in India are 900–1800/ha; in Java, 450 kg/ha, and rarely to 900 kg/ha; in Cuba up to 2700 kg/ha. Trials of 6 cvs in Tunisia gave fiber yields of 880–3670 kg/ha (Jiranek, 1976). Whitely suggests a preharvest cost of ca $300 per hectare to produce kenaf, with yields of 11 MT/ha indicating a per ton cost of $27, $19 at 16 MT/ha, and $15/MT at yields of 2 MT/ha. During 1974, the price range of pulpwood delivered to the mills was $33–44/MT (Whitely, 1981). World production of kenaf is ca 1,300,000 MT per year, mainly produced by Thailand, India, China, USSR, and East Pakistan. The 1971–1972 estimate for Thailand is about 430,000 MT. The chief importers are India, Japan, Belgium, France, Italy, West Germany, Spain, and United Kingdom. Wholesale prices in Mar., Apr., and May 1970 were 160–169 baht/picul (Thailand measures), but prices shot upward in the first half of 1971. In developing countries and Mainland China, the continued growth of bagged or baled agricultural output makes it likely that jute-kenaf usage as sacking materials will continue to grow (an increase of 50% over 1970 was projected for 1980). Seed yields can run ca 700–2000 kg/ha (C.S.I.R., 1948–1976).

Energy

According to the phytomass files (Duke, 1981b), annual productivity ranges from 8–25 MT/ha. Maryland yields though are closer to 4–6 MT/ha (T.A. Campbell, personal communication). Still there are kenaf advocates squared off against the tree advocates. Whitely says, "Kenaf, under favorable conditions, may be several times more productive than trees on a per acre basis... Kenaf dry material could be produced at about half the cost per unit of producing pulpwood." Australians are not quite so optimistic. Stewart et al. say, "The most likely contribution of kenaf to a liquid fuels program would be if the bark were processed to very high quality pulp using some of the core wood as fuel, and the remainder of the core wood were used as a raw material for production of methanol. The bark (40% of stem) has long fibers giving high strength paper pulps. The other 60% (the core wood) is composed of short fibers giving low quality pulp. As a feedstock for liquid fuel production, kenaf yields only lignocellulose. Fuel production is likely to be less than from sugarcane (Stewart et al, 1979). The cost of ethanol from wood using the Rheinau process is estimated at $650 per MT, twice the estimated cost of methanol from wood, based on CSIRO studies for the production of fermentable sugar from kenaf in a plant sized to process 1250 MT wood per day, the amount of kenaf expected from the Ord River region of Australia (comparable to several Australian mills). According to Carlson et al. (1982), kenaf has yields nearly 5 MT/ha DM on abandoned strip mine soil treated with 112 MT/ha sludge. The kenaf accumulated heavy metals. ICAR (1973) reports as much as 13.4 MT total dry matter at Barrackpore, India, corresponding to an uptake of 100 kg N, 65 kg P2O5, 165 kg K2O, 200 kg CaO, and 54 kg MgO.

Biotic Factors

Many fungi attack kenaf, a world survey being the following: Acrostalagmus sp., Aecidium garckeanum, Alternaria diant hi, A. gossypina, A. tenuis, Anthromocopsis sp., Ascochyta hibisci-cannabini, Aspergillus glaucus, A. niger, Botrytis cinerea, Cephalotheca sp., Cercospora abelmoschi, C. abelmoschi-cannabini, C. hisbiscina, C. malayensis, Cladosporium herbarum, Colletotrichum hibisci, C. hibisci-cannabini, C. hibiscicola, Cytospora hibisci, Diplodia hibisci, Diplodina hibisci, Echinobotrium atrum, Epicoccum neglectum, Fusarium culmorum, F. equiseti, F. moniliforme, F. roseum, F. semitectum, F. vasinfectum, Glomerella cingulata, Hyalothyridium nakatae, Illosporium hibisci, Leveillula malvacearum, L. taurica, Macrophomina phaseoli, Macrosporium cladosporoides, M. hibiscinum, Oospora lactis, Pellicularia filamentosa, Penicillium brevicaule, P. crustaceum, P. glacum, P. luteum, Phoma labilis, P. sabdariffae, Phyllosticta hibisci-cannabini, P. hibiscina, Phytophthora parasitica, Pythium parasitica, P. perniciosum, Rhizopus nigricans, Sclerotinia fuckeliana, S. sclerotiorum, Sclerotium rolfsii, Sclerotopsis hibisci, Spicaria elegans, Stysanus stemonitis, Trichosphaeria sp., Vermicularia dematium. The following bacteria are also known to attack kenaf: Agrobacterium tumefaciens and Bacterium hibisci. The following have been isolated from kenaf: Brazilian tobacco streak, Cotton leaf-curl, Groundnut rosette, Yellow vein mosaic, and Anthocyanosis virus. Among nematodes infesting kenaf are: Hemicycliophora penetrans, Helicotylenchus multicinctus, Meloidogyne arenaria, M. hapla, M. incognita., M. incognita acrita, M. javanica, M. thamesi, Pratylenchus brachyurus (Golden, p.c. 1984). The major insect pests are Pink bollworm (Pectinophora gossypiella), Spiny bollworm (Earias sp.), and Cotton aphid (Aphis gossypii) (Reed, 1976).

References

Complete list of references for Duke, Handbook of Energy Crops
Last update Wednesday, January 7, 1998 by aw