This document discusses root and tuber crops, including cassava, cocoyam, potato, sweet potato, taro, and yam. It provides definitions of roots, tubers, and corms, and details the origins, production levels, uses, nutritional profiles, and research centers for the major root and tuber crops. Root and tuber crops provide important sources of food and income, especially in developing countries, as they have high energy production per hectare and tolerate adverse growing conditions better than other crops.
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World Production of Root and Tuber
Crops (106 mt)
0
100
200
300
Million
mt
Potato
Cassava
SwPotato
Yams
Taro
Cocoyam
FAOSTAT, 2003
About half of the potato production
is in the temperate zone
4. Tropical Horticulture - Texas A&M University
Food Utilization of Root and Tuber
Crops (1996 data)
Crop Production
(1,000 mt)
% in
Developing
Countries
Cassava 92,500 > 99.9%
Potato 161,200 40%
Sweet potato 70,100 98%
Yam 16,000 99%
Total 350,900
5. Tropical Horticulture - Texas A&M University
Feed Utilization of Root and Tuber
Crops (1996 data)
Crop Production
(1,000 mt)
% in
Developing
Countries
Cassava 31,000 71%
Potato 54,900 72%
Sweet potato 58,100 >99%
Yam 400 100%
Total 144,800
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Origins of Major Root and Tuber Crops
Cassava
Cocoyam
Potato
Sweet
Potato
Taro
Yam
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Cassava - Manihot esculenta
Yuca, Mandioca, Tapioca
Plant
Slender shrub, 5 m
Enlarged roots
Sweet to bitter
White to yellow
Palmate leaves
Propagation
Stem cuttings
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Cassava - Manihot esculenta
Origin
South America
Distribution
Tropics and subtropics
Staple food in many
tropical regions
Excellent carbohydrate
source
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Cocoyam - Xanthosoma sagittifolium
Malanga, Tannia, Elephant’s Ear
Plant
Perennial herb
Corms and cormels
Propagation
Harvest same plant
multiple times
Portions of central
corm
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Cocoyam - Xanthosoma sagittifolium
Malanga, Tannia, Elephant’s Ear
Origin
West Indies and
northern S. America
Distribution
Tropical regions
Common in
Indonesia
Adaptation
Lowland tropics
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Potato - Solanum tuberosum
Origin
Highlands of South
America
Distribution
Widely cultivated
from highland tropics
to temperate zones
Adaptation
Cool climate
adaptation
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Sweet potato - Ipomoea batatas
Plant
Creeping herb
Enlarged roots vary in
shape and color
Leaves variable in size,
shape, color
Propagation
Young stem cuttings
Important carbohydrate
source
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Sweet potato - Ipomoea batatas
Origin
Central America
Distribution
Widely cultivated both
in tropics and
subtropics
Adaptation
Tropics to subtropics
Below 2200 m altitude
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Taro - Colocasia esculenta
Plant
Perennial herb
Subterraneous stem
Calcium oxalate crystals
Heart shaped leaves
Propagation
Suckers
Corm apices with leaf
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Taro - Colocasia esculenta
Origin
Southeast Asia
Distribution
West Africa
Caribbean
Pacific islands
Staple food
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Yam
Dioscorea alata, cayenensis and rotundata
(Sixty species cultivated for food and pharmaceuticals)
Plant
Climbing vine, 10 m
Tubers vary in
shape
Leaves ovate with
cordate base
Propagation
Tubers
Staple food in arid
regions of Africa
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Yam
Dioscorea alata, cayenensis and rotundata
(Sixty species cultivated for food and pharmaceuticals)
Origin
Asia and West Africa
Production
Mainly Africa
Adaptation
Lowland tropics
Drought tolerant
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Plant Adaptation
Crop Rain
(mm)
Temperature
(ºC)
Drought
Cassava 1,000-1,500 25-29 Yes
Cocoyam 1,400-2,000 13-29 No
Potato 500-750 15-18 No
Sweet potato 750-1,000 >24 Yes
Taro 2,500 21-27 No
Yam 1,150 25-30 Yes
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Plant Soil Adaptation
Crop Fertility
needs
OM
requirement
Tolerant of
swampy land
Cassava Low Low No
Cocoyam High High No
Potato High High No
Sweet potato Low Low No
Taro High High Yes
Yam High High No
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Plant Storage Duration
Crop Storage time in
ground
Post harvest
storage life
Cassava Long Short
Cocoyam Long Long
Potato Short Long
Sweet potato Long Short
Taro Moderate Variable
Yam Long Long
23. Tropical Horticulture - Texas A&M University
Crops compared for Edible Energy
Production
Crop Edible energy production
MJ/ha/day
Potato 216
Yam 182
Maize 159
Sweet potato 152
Rice 151
Wheat 135
Cassava 121
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Crops compared for Edible Protein Production
Crop Edible protein production
kg/ha/day
Cabbages 2.0
Potato 1.4
Dry peas 1.4
Wheat 1.3
Lentils 1.3
Tomatoes 1.2
Chickpeas 1.1
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Nutritional aspects of root and tuber crops
Crop Starch
% FW
Protein
% FW
Vitamin A
mg/100g FW
Vitamin C
mg/100g FW
Cassava 27-36 0.5-2.0 17 50
Potato 13-16 2.0 Trace 31
Sweet potato 18-28 1.0-2.5 900 35
Yam 18-25 2.5 117 24
Aroids 19-21 2.0 0-42 9
FW = fresh weight
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Nutritional Composition of 100 g of Food
Crop Percent
water
Protein (g) Food energy
kcal
Fats
(g)
Cassava 68 0.9 124 0.1
Beans 69 7.8 118 0.6
Sweet potato 71 1.7 114 0.4
Rice 73 2.0 109 0.1
Yam (raw) 74 2.1 101 0.2
Potato 80 2.1 76 0.1
Plantains 80 1.3 77 0.1
Maize (grits) 87 1.2 51 0.1
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Importance of Root and Tuber Crops
Important source food and income for
the most food insecure households
Why?
High energy production per ha/day
Yield better under adverse conditions
than other crops
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Future Trends for Root and Tuber
Crops
Increased regional production
concentration
Sub Saharan Africa, 60% cassava production
West Africa, 90% yam production
China, 82% of sweet potato production
Increased specialization of End Use
Increase of processed forms of food
Increased use of root/tubers for feed and
starch derived products
Relative importance remain same
10.5% of agricultural value
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International Research Centers
involved with Root and Tuber Crops
CIAT (Colombia)
Cassava for Americas and Asia
CIP (Peru)
Potato
Sweet potato
Andean roots and tubers
IITA (Nigeria)
Cassava for Africa
Yam for Africa
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International Research Centers
involved with Root and Tuber Crops
CIAT
CIP
IITA