1. Root and Tuber Crops in the Tropics
Cassava
Cocoyam
Potato
Sweet Potato
Taro
Yam

2. Tropical Horticulture - Texas A&M University
Definitions
Root (cassava, sweet potato)
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
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3. Tropical Horticulture - Texas A&M University
Definitions
Rhizome
Rootlike stem
Upper part with leafy stems
Lower part with roots
Bulb (lily, onion, tulip)
A bud, usually underground
Short thick stem
Roots from below
Overlapping scalelike leaves
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4. World Production of Root and Tuber Crops (106 mt)
FAOSTAT, 2003
About half of the potato production is in the temperate zone
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5. Food Utilization of Root and Tuber Crops (1996 data)
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6. Feed Utilization of Root and Tuber Crops (1996 data)
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7. Origins of Major Root and Tuber Crops
Yam
Cocoyam
Sweet
Potato
Cassava
Taro
Potato
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8. 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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9. Cassava - Manihot esculenta
Origin
South America
Distribution
Tropics and subtropics
Staple food in many tropical regions
Excellent carbohydrate source
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10. 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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11. 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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12. Potato - Solanum tuberosum
Plant
Herbaceous
Subterannean stems
Leaves
Propagation
Eyes from tubers
Important staple crop
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13. 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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14. 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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15. 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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16. Taro - Colocasia esculenta
Plant
Perennial herb
Subterraneous stem
Calcium oxalate crystals
Heart shaped leaves
Propagation
Suckers
Corm apices with leaf
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17. Taro - Colocasia esculenta
Origin
Southeast Asia
Distribution
West Africa
Caribbean
Pacific islands
Staple food
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18. Tropical Horticulture - Texas A&M University
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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19. Tropical Horticulture - Texas A&M University
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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20. Plant Characteristics
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21. Tropical Horticulture - Texas A&M University
Plant Adaptation
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22. Tropical Horticulture - Texas A&M University
Plant Soil Adaptation
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23. Plant Storage Duration
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24. Crops compared for Dry Matter Production
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25. Crops compared for Edible Energy Production
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26. Crops compared for Edible Protein Production
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27. Nutritional aspects of root and tuber crops
FW = fresh weight
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28. Nutritional Composition of 100 g of Food
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29. 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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30. 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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31. 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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32. International Research Centers involved with Root and Tuber Crops
CIAT
IITA
CIP
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33. Tropical Horticulture - Texas A&M University
Any Questions?
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