Root and Tuber Crops in
the Tropics
Definitions
] Root (cassava, sweet potato)
Cassava
Cocoyam
Potato
Sweet Potato
Taro
Yam
\ No leaves or reproductive organs
] Tuber (potato, yams)
\ Fleshy underground stem
\ Minute scale leaves with buds (eyes)
] Corm (aroids, cocoyam and taro)
\ Short, bulblike underground upright stem
\ With scale leaves
Tropical Horticulture - Texas A&M University
World Production of Root and Tuber
Crops (106 mt)
Definitions
] Rhizome
Million mt
\ Rootlike stem
\ Upper part with leafy stems
\ Lower part with roots
] Bulb (lily, onion, tulip)
FAOSTAT, 2003
300
200
100
About half of the potato production
is in the temperate zone
Tropical Horticulture - Texas A&M University
Cassava
Potato
Production
(1,000 mt)
Cocoyam
Taro
Tropical Horticulture - Texas A&M University
Food Utilization of Root and Tuber
Crops (1996 data)
Crop
Yams
[ Roots from below
[ Overlapping scalelike leaves
SwPotato
Potato
Cassava
0
\ A bud, usually underground
\ Short thick stem
92,500
% in
Developing
Countries
> 99.9%
Feed Utilization of Root and Tuber
Crops (1996 data)
Crop
Production
(1,000 mt)
Cassava
31,000
% in
Developing
Countries
71%
161,200
40%
Potato
54,900
72%
Sweet potato
70,100
98%
Sweet potato
58,100
>99%
Yam
16,000
99%
Yam
400
100%
Total
350,900
Total
144,800
Tropical Horticulture - Texas A&M University
Tropical Horticulture - Texas A&M University
1
Cassava - Manihot esculenta
Origins of Major Root and Tuber Crops
Yuca, Mandioca, Tapioca
] Plant
Yam
Cocoyam
Sweet
Potato
\ Slender shrub, 5 m
\ Enlarged roots
[ Sweet to bitter
[ White to yellow
\ Palmate leaves
Cassava
Taro
] Propagation
\ Stem cuttings
Potato
Tropical Horticulture - Texas A&M University
Cassava - Manihot esculenta
] Origin
Tropical Horticulture - Texas A&M University
Cocoyam - Xanthosoma sagittifolium
Malanga, Tannia, Elephant’s Ear
] Plant
\ South America
] Distribution
\ Tropics and subtropics
] Staple food in many
tropical regions
\ Excellent carbohydrate
source
\ Perennial herb
\ Corms and cormels
] Propagation
\ Harvest same plant
multiple times
\ Portions of central corm
Tropical Horticulture - Texas A&M University
Cocoyam - Xanthosoma sagittifolium
Malanga, Tannia, Elephant’s Ear
Tropical Horticulture - Texas A&M University
Potato - Solanum tuberosum
] Plant
] Origin
\ West Indies and
northern S. America
] Distribution
\ Tropical regions
\ Common in
Indonesia
] Adaptation
\ Herbaceous
\ Subterannean stems
\ Leaves
] Propagation
\ Eyes from tubers
] Important staple crop
\ Lowland tropics
Tropical Horticulture - Texas A&M University
Tropical Horticulture - Texas A&M University
2
Potato - Solanum tuberosum
Sweet potato - Ipomoea batatas
] Plant
] Origin
\ Highlands of South
America
] Distribution
\ Widely cultivated
from highland tropics
to temperate zones
] Adaptation
\ Cool climate
adaptation
\ Creeping herb
\ Enlarged roots vary in
shape and color
\ Leaves variable in size,
shape, color
] Propagation
\ Young stem cuttings
] Important carbohydrate
source
Tropical Horticulture - Texas A&M University
Sweet potato - Ipomoea batatas
] Origin
\ Central America
] Distribution
\ Widely cultivated both
in tropics and
subtropics
] Adaptation
\ Tropics to subtropics
\ Below 2200 m altitude
Tropical Horticulture - Texas A&M University
Taro - Colocasia esculenta
] Plant
\ Perennial herb
\ Subterraneous stem
[ Calcium oxalate crystals
\ Heart shaped leaves
] Propagation
\ Suckers
\ Corm apices with leaf
Tropical Horticulture - Texas A&M University
Tropical Horticulture - Texas A&M University
Yam
Taro - Colocasia esculenta
Dioscorea alata, cayenensis and rotundata
(Sixty species cultivated for food and pharmaceuticals)
] Plant
] Origin
\ Southeast Asia
] Distribution
\ West Africa
\ Caribbean
\ Pacific islands
] Staple food
\ Climbing vine, 10 m
\ Tubers vary in
shape
\ Leaves ovate with
cordate base
] Propagation
\ Tubers
] Staple food in arid
regions of Africa
Tropical Horticulture - Texas A&M University
Tropical Horticulture - Texas A&M University
3
Yam
Dioscorea alata, cayenensis and rotundata
(Sixty species cultivated for food and pharmaceuticals)
] Origin
Plant Characteristics
Crop
\ Asia and West Africa
] Production
\ Mainly Africa
] Adaptation
\ Lowland tropics
\ Drought tolerant
Cassava
Growth
period (mo)
9-24
Annual or
perennial
Perennial
Cocoyam
9-12
Perennial
Corms
Potato
3-7
Annual
Tubers
Vine cuttings
Sweet potato
3-8
Perennial
Taro
6-18
Perennial
Corms
Yam
8-11
Annual
Tubers
Tropical Horticulture - Texas A&M University
Tropical Horticulture - Texas A&M University
Plant Adaptation
Crop
Rain
(mm)
Planting
material
Stem cuttings
Plant Soil Adaptation
Temperature
(ºC)
Drought
Crop
Fertility
needs
OM
Tolerant of
requirement swampy land
Cassava
1,000-1,500
25-29
Yes
Cassava
Low
Low
No
Cocoyam
1,400-2,000
13-29
No
Cocoyam
High
High
No
Potato
500-750
15-18
No
Potato
High
High
No
Sweet potato
750-1,000
>24
Yes
Sweet potato
Low
Low
No
Taro
2,500
21-27
No
Taro
High
High
Yes
Yam
1,150
25-30
Yes
Yam
High
High
No
Tropical Horticulture - Texas A&M University
Tropical Horticulture - Texas A&M University
Plant Storage Duration
Crops compared for Dry Matter Production
Crop
Storage time in
ground
Post harvest
storage life
Crop
Cassava
Long
Short
Yam
2.4
Potato
2.2
Cocoyam
Long
Long
Potato
Short
Sweet potato
2.1
Long
Rice
1.9
Bananas
1.5
Wheat
1.3
Maize
1.3
Sweet potato
Long
Short
Taro
Moderate
Variable
Yam
Long
Long
Tropical Horticulture - Texas A&M University
Cassava
Dry matter production
Mt/ha/day
3.0
Tropical Horticulture - Texas A&M University
4
Crops compared for Edible Energy Production
Crop
Crops compared for Edible Protein Production
Crop
Edible energy production
MJ/ha/day
216
Potato
Edible protein production
kg/ha/day
2.0
Cabbages
Yam
182
Potato
1.4
Maize
159
Dry peas
1.4
Sweet potato
152
Wheat
1.3
Rice
151
Lentils
1.3
Wheat
135
Tomatoes
1.2
Cassava
121
Chickpeas
1.1
Tropical Horticulture - Texas A&M University
Tropical Horticulture - Texas A&M University
Nutritional aspects of root and tuber crops
FW = fresh weight
Crop
Starch
Protein Vitamin A Vitamin C
% FW
% FW
mg/100g FW
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
Tropical Horticulture - Texas A&M University
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
Nutritional Composition of 100 g of Food
Crop
Cassava
Beans
Sweet potato
Rice
Yam (raw)
Potato
Plantains
Maize (grits)
Percent
water
68
69
71
73
74
80
80
87
Protein (g) Food energy
kcal
0.9
124
7.8
118
1.7
114
2.0
109
2.1
101
2.1
76
1.3
77
1.2
51
Fats
(g)
0.1
0.6
0.4
0.1
0.2
0.1
0.1
0.1
Tropical Horticulture - Texas A&M University
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
Tropical Horticulture - Texas A&M University
Tropical Horticulture - Texas A&M University
5
International Research Centers
involved with Root and Tuber Crops
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
Tropical Horticulture - Texas A&M University
CIAT
IITA
CIP
Tropical Horticulture - Texas A&M University
Any Questions?
Tropical Horticulture - Texas A&M University
6