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Manihot esculenta Crantz

Euphorbiaceae
Cassava, Tapioca, Manioc, Mandioca, Yuca

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 unpublished.


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

Uses

Cassava is grown primarily for the tubers which are used as a foodstuff. Tubers may be eaten raw, boiled or fried, or in baked goods. Since there is HCN in the skin of sweet varieties, they must be peeled first before eating. In bitter varieties the HCN is throughout the root, which must be cooked before using. From the manioc tuber are obtained starch, farina, a whole flour, grated manioc and tapioca. Tapioca is used as a thickener in puddings and soups; an industrial starch is used in baked goods, laundry and paper industries, and for sizing cotton fabrics and other textiles; from the starch a glue is prepared useable on postage stamps. Young leaves are high in Vitamin B and are a good remedy for beriberi, but they have the highest HCN content; however, they are sometimes used as a vegetable and for hog food. In the Philippines tubers are reduced to a pulp, wrapped with shredded coconut meats and sugar in banana leaves and boiled; then served as a dessert (suman). Roots may be used as fodder for livestock. Manioc is also the source of alcoholic beverages, or power alcohol.

Folk Medicine

Medicinally, the poisonous juice is boiled down to a syrup and given as an aperient (Guiana). Fresh rhizome made into a poultice is applied to sores. The flour cooked in grease, the leaf stewed and pulped, and the root decocted as a wash are said to be folk remedies for tumors. According to Hartwell (1967–1971), cassava is used in folk remedies for cancerous affections, condylomata, excrescences of the eye, and tumors. Reported to be antiseptic, cyanogenetic, demulcent, diuretic, and POISON, cassava is a folk remedy for abscesses, boils, conjunctivitis, diarrhea, dysentery, flu, hernia, inflammation, marasmus, prostatitis, snakebite, sore, spasm, swellings, and testicles. (Duke and Wain, 1981)

Chemistry

Milky juice contains an essential oil (0.13%), saponin (1.14%), glucosides and dyes, the essential oil containing sulfur in organic combination. Per 100 g the leaves are reported to contain 60 calories, 81.0 g H2O, 6.9 g protein, 1.3 g fat, 9.2 g total carbohydrate, 2.1 g fiber, 1.6 g ash, 144 mg Ca, 68 mg P, 2.8 mg Fe, 4 mg Na, 409 mg K, 8,280 mg b-carotene equivalent, 0.16 mg thiamine, 0.32 mg riboflavin, 1.80 mg niacin, and 82 mg ascorbic acid. Per 100 g, the root is reported to contain 135 calories, 65.5 g H2O, 1.0 g protein, 0.2 g fat, 32.4 g total carbohydrate, 1.0 g fiber, 0.9 g ash, 26 mg Ca, 32 mg P, 0.9 mg Fe, 2 mg Na, 394 mg K, 0.05 mg thiamine, 0.04 mg ribof lavin, 0.6 mg niacin, and 34 mg ascorbic acid.

Toxicity

The genus Manihot is reported to contain the following "toxins": acetone (oral LD50 5,300) hydrocyanic acid (oral LD50 3.7), 787 oxalic acid (700 mg; human oral LDLo), saponin (mouse oral LDLo, 3,000), and tryptophane (oral rat TDLo 1,100 mg).

Description

Shrub or small tree, 1.3–5 m tall; with fleshy elongated tuberous roots or rhizomes, these very woody, only slightly thickened in wild varieties, under cultivation up to 2.5 m long and 10–15 cm in diameter, weighing up to 40 kg, averaging 4–7 kg; leaves usually deeply 3–7-parted with spatulate to linear-lanceolate acuminate lobes 7.5–15 cm long, glabrous, glaucous beneath and minutely puberulent along veins, long petioled; flowers in panicles, less than 1.2 cm long; capsules globose, about 1.2 cm across, with 6 winged angles; seeds 3 per capsule.

Germplasm

There are innumerable cultivated varieties of manioc, 160 or more. They are divided into bitter and sweet. Bitter manioc is characterized by its erect stalk, almost red-colored leaves and early heavy yields, and since they contain between 0.02–0.003% prussic acid are used to make industrial starch. Sweet manioc containing 0.007% prussic acid with most of HCN in the skin and outer cortical layer is used to eat as food and for fodder. Some cvs now in use are: 'Baker', 'Copeland', 'Red Manila', 'Jolo White', 'Manioca Basiorao', 'Aipin Mangi', 'Aipin Valence', 'Aipin Maxteiga', 'Yellow Bell', 'Blue Beard', 'Pacho III', 'Singapore', 'Constantin', 'Pittier', 'Florida Sweet', 'Cenaguen', etc. There are many cvs in every country where the crop is grown. Reported from the South American, and secondarily from the Middle American and Indochina-Indonesian Centers of Diversity, cassava or cvs thereof is reported to tolerate aluminum, drought, high pH, insects, laterites, low pH, photoperiodic variances, poor soil, shade, viruses, and wind. (Duke, 1978) (2n = 36)

Distribution

Native to South America where it is extensively cultivated also. Cultivated in the tropics and sometimes in the subtropics of the Old and New World as an important food and a source of starch. It is the second most important root crop in India. Many countries have developed extensive programs to further the raising of this crop, e.g. (Mexico, Central America, Brazil, Colombia, Jamaica, Africa, Ghana, Madagascar, Indonesia, Federated Malay States, Thailand, India, Philippine Islands, Paraguay, Fiji, and Sri Lanka). Manihot is not known in the wild state, but there are two centers of speciation, one in Central America from southern Mexico to Guatemala and another in northeastern Brazil. Sweet cassavas are more widely distributed in South America than bitter varieties, and were cultivated by older civilizations, as long as 4,000 years ago in Peru and 2,000 years ago in Mexico.

Ecology

Manioc will grow in all well-drained tropical and subtropical areas of the world where there is a warm humid climate. It requires a fairly well-spaced rainfall of about 15 dm for optimum growth of the crop. It will not tolerate frost, and usually does not grow above 1,100 m altitude. It grows best in welldrained neutral to alkaline, quite permeable, sandy loams. The plants need a lot of water, but must not stand in water; in lowlands the plants are ridged. Ranging from Warm Temperate Dry to Moist through Tropical Very Dry to Wet Forest Life Zones, cassava is reported to tolerate annual precipitation of 6.4 to 40.3 dm (mean of 56 cases = 16.4), annual temperature of 14.7 to 27.8°C (mean of 23.8 cases = 56), and pH of 4.5 to 8.7 (mean of 42 cases = 6.2).

Cultivation

For agricultural purposes, cassava is propagated exclusively by vegetative means from stem-cuttings. It is raised from seed only for the purpose of selection. A field is thoroughly prepared with an application of basal dressing of farmyard manure. Thick, strong shoots about 15–20 cm long with a minimum of 3 or 4 buds, preferably taken from the middle of the branch, are used. No more shoots should be prepared than can be planted in one day. Bruised and long-exposed cuttings may fail roots. From one good hectare of manioc one should obtain enough selected cuttings to plant 3–4 hectares. Cassava is usually planted at the beginning of the rainy season, but where rain is well-distributed it can be planted any time of the year. Distance between plants depends on the varieties chosen and the fertility of the soil, (usually 1.20 m to 1.50 m by 80 cm for good cvs on fertile soils; 1 m each way for weak cvs on poor soils). Furrows are dug to a depth of 15 to 20 cm or pits dug, and the cuttings are planted erect by hand, covering them immediately with 8–10 cm of soil. This operation is done with the feet, a spade or an ordinary plow. At least two weedings are necessary, and after 1–2 weeks plants which did not grow should be replaced. Good cultivations to about the depth of 25 cm are needed until the plants shade out the weeds. Since cassava is an exhaustive crop, an application of manure and ashes, or phosphates, may be necessary. Pruning practices are used when one wishes to leave manioc plantations from one year to another, this practice only being used when there is great necessity for using the shoots and leaves as forage, or in those cases where there is danger of heavy frosts which might decay the roots, or in order to insure branches for new plantings. Cassava may be rotated with rubber trees, interplanted with bananas, vegetables or sweet potatoes.

Harvesting

Cassava is harvested in 10–14 months, depending on the cv, the cultural practices and the purpose of the crop, but mostly within the first year. When the crop is intended for food purposes, harvest may commence at 8–10 months, when tubers are still tender and premature. Skilled labor is not necessary and most of the harvesting is manual or with simple mechanical equipment. Field processing is necessary to keep down the deteriorating effects of enzyme action. Central processing using electric motors and diesel engines, especially for rasping the tubers, can increase production of starch to 5 tons a day. Tubers are dug, washed, rasped, or peeled and crushed, finally separating the starch from the inner tuber. Additional processes consists of rewashing and drying the starch, and converting it into farina, tapioca or other by-products. Manioc reaches its maximum production on completing the second vegetative cycle, when it is 18–24 months old, its production nearly doubling. After harvesting, the stems are stored in a dry place until the next planting.

Yields and Economics

In India 15–20 MT/ha of tubers are obtained depending on growing conditions, soil and amount of water during growing season. In South America up to 36 tons have been harvested from a hectare, with about 8,000 plants per hectare. World acreage has been estimated to be about 7 million hectares, more than half of which is grown in Africa. Although very little cassava enters into international trade, the world production is about 62 million tons. The main exporting countries at present are Brazil, Indonesia and Madagascar. United States and European countries are the principle importing countries.

Energy

For cassava-based alcohol production with firewood for fuel, the ratio of energy produced to that consumed is 1.07; with cassava stalks as fuel the ratio is 4.97. (Palz and Chartier, 1980) Coombs and Vlitos (1978) suggest that cassava will yield 29 MT root per hectare, each ton yielding about 170 liters of alcohol or 5,000 liters per hectare. To calculate aerial biomass multiply the production or yield figures by 0.2 (Smil, 1979) to 0.7 (Boardman, 1980). I use 0.5. The skin and pith constitute 27% of production (Wu Leung, et al 1972). According to Devendra and Raghavan (1978), there is 55–59% residue in the manufacture of tapioca. Averaged over the 365-day growing season, cassava in Java had a mean growth rate of 11 g/m2/day for an annual production of 41 MT/ha. In northern Queensland, cassava is assumed to yield 12 MT tops, 17.5 MT tubers with respective growing and harvest costs of $A 24.50 and 31.00, transport costs of $A 3.50 and $A 3.40/MT, and energy inputs of 870 and 1210 MJ/MT. Cassava is an attractive fuel crop because it can give high yields of starch and total dry matter in spite of limited drought and poor soil. Energy inputs for cassava represent only 5–6% of the final energy content of the total biomass, showing an energy profit of 95%, assuming complete utilization of the energy contained in the biomass. Alcohol production from cassava has an overall efficiency of 32%. The figures above would indicate a harvest index of ca 60%. To convert root yields to total biomass, one might multiply by ca 1.6. To calculate aerial biomass (residue), multiply root yield by ca 0.7. Brazil ultimately plans to satisfy its liquid fuel requirements with alcohol from cassava and sugarcane (Boardman, 1980). Ironically, Gaydou et al (1982) figure this as the lowest energy producer of 6 they considered for Madagascar, producing ca 1000 liters alcohol/ha, cf 1,600 liters oil for Ricinus, 2250 liters oil for Aleurites, 2450 liters oil for Jatropha, 2450 liters ethanol for Saccharum, arid 3,800 liters oil for Elaeis.

Biotic Factors

Cassava has varying numbers of pests in various localities. A worldwide survey shows the following fungi attacking the crop: Absidia cristata, Armillaria mellea, Asterina manihotis, Botryodiplodia theobromae, Botryosphaeria ribis, Cercospora cearae, C. caribaea, C. henningsii, C. manihotis, Colletotrichum manihotis, Corticium rolfsii. Corynespora cassiicola, Diplodia manihotis, Fomes lignosus, F. noxius, Fusarium gibbosum, F. solani, Ganoderma lucidum, Gleosporium manihotis, Glomerella singulata, S. manihotis, Haplographium manihoticola, Hendersonula toruloidea, Hypomyces haematococcus, Irenia entebbensis, Lasiodiplodia theobromae, Megalonectria pseudotrichia, Microsphaeria euphorbiae, Oidium manihotis, Ophiobolus manihotis, Periconia byssoides, P. pycnospora, Phaebotryosphaeria plicatula, Phymatotrichum omnivorum, Physalospora abdita, Ph. rhodina, Phyllosticta manihot, Phytophtora parasitica, Polyporus sapureme (rotting or roots, "saporema," stinking-rot), Polystictus occidentalis, Ragnhildiana manihotis, Rhizopus stolonifer, Rhizoctonia solani, Rosellinia bunodes, Schizophylum alneum, Sclerotium rolfsii, Sphaceloma manihoticola, Tryonectria pseudotrichia, Uromyces janiphae and Verticillium dahliae. Among the bacteria Bacillus manihoti causes Bacillosis or Basilosis, a stemrot, which can be controlled with Bordeaux mixture, and by the use of healthy shoots, rotation of the crop and sterilization of the cuttings before planting. Other bacteria attacking cassava are: Bacterium robici, Pseudomonas solanacearum, and Xanthomonas manihotis. The following viruses have been isolated from Cassava: Brown Streak, Bunchy top, Leaf-roll and a mosaic. A large number of nematodes infest the roots of cassava in different parts of the world, a survey indicating the following: Aphelenchoides avenae, Criconemella sphaerocephala, Diploscapter rhizophilus, Ditylenchus dipsaci, Helicotylenchus cavenessi, H. concavus, H. microcephalus, H. pseudorobustus, Hemicycliophora penetrans, Meloidogyne incognita acrita, M. javanica, Peltamigratis nigeriensis, Pratylenchus brachyurus, P. coffeae, P. zeae, Rotylenchulus reniformis, Scutellonema bradys, S. clathricaudatum, Trilineellus triglyphus, and Xiphinema elongatum. In the Philippines white ants are a pest during the germinating period, and wild hogs damage the crops by eating the tubers. Insects are pests in many areas: Stalk-borers (Curcullionida, Sternocoelus granicollis), Stink-bugs (Aleurothrix usaipim and Asterochiton manihoti), galls or swellings in the leaves caused by larvae of flies (Iatrophobia brasiliensis), mosaic of biting insects (Eutrips manihoti), and night-flying moths during their larval stages (Erinnyis ello and E. Aolpe) (attack leaves of manioc) controlled by a parasitic fly that attacks the chrysalis.

References

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