dioscorea spp. A root crop or tubers. This presentation includes its origin, history and domestication, some of its classifications and varities.

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2. (Dioscorea spp.)
• Yams are starchy staples in the form of large
tubers produced by herbaceous annual and
perennial trailing vines grown in Africa, the
Americas, the Caribbean, South Pacific and Asia.
It’s vines can be smooth or pricky, reaching 10 m (32.8 ft) or
more in length depending on the variety.
It’s leaves are simple and usually oval to heart-shaped with petioles
which are the same length, or slightly longer, than the leaf blade
itself.

3. • This plant can produce one singular tuber or
several tubers which extend from stolons
from a central corm (up to 20)
• The tubers can be cylindrical, curved or
lobed, with brown, grey, black or pink skin
and white, orange or purplish flesh.

4. …the tubers of yam have organoleptic
qualities that can be make them the pre-
ferred carbohydrates staple and can
contribute up to 350 calories per person
each day? (Asiedu et al., 2001)
…yams are produced over 5 million hectares
in 47 countries in tropical and subtropical
regions of the world?

5. • Lebut (2009) stated that the genus dispersed worldwide at the end of
Cretaceous period, evolved in the different directions throughout the New
and Old World, and resulted in distinct species.
• The main dispersal regions included:
Americas
Madagascar
South and Southeast Asia
Melanesia
Australia

6. • According to Coursey (1967), the separation of the Asian and African species
occurred later, during the Miocene period. Furthermore, D. alata and D.
esculenta, originated from Burma and Assam, localities of Southeast Asia.
D. esculenta
D. alata

7. • Degres (1993) noted that D.
cayenesis is of African origin,
given that wild species can be
found on the continent.
• The origins of other yam cultivated
species are African and Asian, except
for D. trifida, whose origin is South
America (Lebut, 2009)
Yellow Yam

8. Kindom Plantae
Subkingdom Tracheobionta
Division Liliopsida
Subclass Liliidae
Order Liliales
Superdivision Spermatophyta
Genus Dioscorea
Family Dioscoreacreae
Yam
Flowering Plants
Yam Family
Vascular Plants
Plants
Seed Plants
Class Liliopsida Monocotyledons

9. Dioscorea alata L. (Water yam)
Yellow Guinea Yam
Hottentot Bread
Dunguey
Air yam

10. Importance/Uses to Man and Animals
• Yams are:
valuable source of carbohydrates, fibers, and low level of fats
processed into various staple intermediate and end product forms (Jaleel et
al., 2007)
• Dioscorea species are:
important source of secondary metabolites used in pharmaceutical industry
and medicine.
(wild species) sources of compounds used in synthesis of sex hormones and
corticosteroids (Coursey, 1967).
(cultivated species) sources of food in some other countries (Coursey, 1967).

11. Importance/Uses to Man and Animals
• The plant has many aerial tubers that also aid in reproduction.
• Powdered tubers are used as a remedy for piles, gonorrhea and are
applied externally to sores.
• Some tubers of Dioscorea are important sources of diosgenin (Satour
et al., 2007)
• Yams are used for consumptions for both humans and animals.
Nigerian Yam Porridge Chips

12. Importance/Uses to Man and Animals
• Wu et al. (2005) analyzed the consumption of D. alata and
concluded that although the mechanisms are not yet fully
understood, it’s consumption can reduced risk of breast cancer
and cardiovascular disease.
• Traditional medicines used yams to cleanse skin impurities.
• Yams can treat anemia giving wealth nutrients (Okwu &Ndu,
2006).
• Tubers are responsible for increased fertility in women who
habitually consume it (Balbach & Boarim, 1993).
• Dioscorea are used for the treatment of Addison’s disease,
some allergies, bursitis, contact dermatitis, psoriasis,
rheumatoid arthritis, sciatic, Brown Recluse Spider Bites, insect
stings, and other diseases and ailments (Foster and Duke,
1990).

13. Approximate Yam Nutrition per 100g
9mg Salt
17 mg calcium 17 mg Vit. C
32 mg Vit. B2 55 mg Phosphorus
112 mg Vit. B1 816 mg Potassium
1 g Protein 4 g Fiber
23 g Sugar 103 Calories
It does not have any
Vitamin A, iron, fat, and
no vitamin B3.

14. Major Constraints/Problems in the Philippines
• Limited supply of planting materials.
• Lack of information about yam production, processing,
product development, preservation and market-linkaging.

15. Production Practice and Management
Growing Conditions
• Soil PH Acidic, Neutral, Alkaline
• Soil Drainage Average
• Soil Type Clay, Loam
• Growth Rate Very Fast
• Water Requirements Average Water
• Habit Vining/Climbing
• Seasonal Interest Summer, Fall

16. Production Practice and Management
Growing Conditions
• Land Preparation Loose soils with organic matter more
suitable for the Dioscorea spp.
Large size pits must be prepared with
the rigid soil. Normal size of the pit is
about 1X1X1 feet. Straw, coconut
husk, paddy husk as well as grass
debris can be used as organic matter.
Pits are filled with these matter and
tubers with active bud can
be planted on it.

17. Production Practice and Management
Growing Conditions
• Recommended Spacing Greater yam: 1X1
Lesser yam: 1X0.5
• Fertilizer Recommendation Fertilizer application must be done before
4.5 months to obtain optimum growth rate.
Not necessary to apply fertilizer after that.
Time of application Amount (kg/ha)
TSP Urea MOP
Basal Dressing 65 150 60
1 Top dressing (1.5-2 months after planting) 65 - 60
2 Top dressing (3.5-4 months after planting) 65 - 60

18. Production Practice and Management
Growing Conditions
• Weed management Weed control must ne done prior to top dressing.
Mulching is important to weed control as well as
soil and water conservation.
Yam is considered as a high value crop.
Stony and highly compacted soils are not good for yam production.
Salinity and acidity dominate the problems related to agricultural land use.

19. Major Pests and Diseases Attacking Yam
and their control
• Main diseases and account for the highest field and storage losses in susceptible cultivars (Abang et al.,
2003):
Virus (Yam Mosaic Virus or YMV)
Anthracnose and Scutellonema bradys
- anthracnose stands out as the principal phytosanitary problem in several areas of yam
cultivation and production.
Nematodes
- which interact with fungi and bacteria, attack the tubers in the field and continue to
cause damage in the post harvest.
 Dry rot disease
-a limiting factor in yam cultivation and negatively influences the
market value of the product, especially when found in conjunction with the
nematode Scutellonema bradys, which acts as its etiologic agent.
 Yam meloidogynoses are diseases that cause heavy losses in yam
production and marketing (Abang et al., 2002; Royeroet al., 2007)

20. Major Pests and Diseases Attacking Yam
and their control
Yam infected by Rot and Anthracnose
Yam infected by Anthracnose
Yam (left) infected by Nematodes
Yam infected by Dry Rot
Yam (Leaf) infected by Yam
Mosaic Virus

21. Major Pests and Diseases Attacking Yam
and their control
• Micropropagation and and Organogenesis are two of many
biotechnological techniques that could be adopted to obtain healthy
seedlings, increasing the potential of cultivation (Alizadeh et al., 1998;
Chen et al., 2003; Royeroet al., 2007) especially in commercially D. alata
(Bagolun et al., 2006).

22. Economic and Marketing in the Global Market
• Yam is the currently the 4th most important tuber-root crop in the world,
after potato, cassava, and sweet potato; second most important tropical
root or tuber crop.
• In 2008, the estimated world production of yams was 51.7 M tons, with
Africa leading the production.
• West Africa accounts for 90%-95% of world yam production with Nigeria
the largest single producer.

24. Credits to:
Hyacinth “Pepa” Espera for making this PowerPoint presentation possible.