Manihot esculenta Crantz
Cassava, Tapioca, Manioc, Mandioca, Yuca
Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.
- Folk Medicine
- Yields and Economics
- Biotic Factors
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.
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
(19671971), 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)
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.
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
Shrub or small tree, 1.35 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 1015 cm in diameter, weighing up to 40 kg,
averaging 47 kg; leaves usually deeply 37-parted with spatulate to
linear-lanceolate acuminate lobes 7.515 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.
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 0.020.003% 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)
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.
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).
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 1520 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 34 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 810 cm
of soil. This operation is done with the feet, a spade or an ordinary plow.
At least two weedings are necessary, and after 12 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.
Cassava is harvested in 1014 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 810 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 1824 months old, its production nearly
doubling. After harvesting, the stems are stored in a dry place until the next
In India 1520 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.
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 5559% 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 56% 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
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.
Complete list of references for Duke, Handbook of Energy Crops
- Boardman, N.K. 1980. Energy from the biological conversion of solar energy.
Phil. Trans. R. Soc. London A 295:477489.
- Coombs, J. and Vlitos, A.J. 1978. An assessment of the potential for biological
solar energy utilization using carbohydrates produced by higher plant
photosynthesis as chemical feedstock. vol. 2. Proc. Internat. Solar Energy
Society Congress, New Delhi, India. Pergamon Press, New York.
- Devendra, C. and Raghavan, G.V. 1978. Agricultural by-products in South East
Asia: availability, utilization and potential value. World Rev. Anim. Prod.
- Duke, J.A. and Wain, K.K. 1981. Medicinal plants of the world. Computer index
with more than 85,000 entries. 3 vols.
- Hartwell, J.L. 19671971. Plants used against cancer. A survey. Lloydia 3034.
- Palz, W. and Chartier, P. (eds.). 1980. Energy from biomass in Europe. Applied
Science Publishers Ltd., London.
- Smil, V. 1984. On energy and land. Am. Scientist 72(1):1521.
- Wu Leung, Woot-Tsuen, Butrum, R.R., and Chang, F.H. 1972. Part I. Proximate
composition mineral and vitamin contents of east Asian foods. In: Food
composition table for use in east Asia. FAO & U.S. Dept. HEW.
Last update Wednesday, January 7, 1998 by aw