Yams: Traditional ways of managing their diversity for food security in southern Ghana - Managing Agrodiversity the Traditional Way - page 81

Special attributes and uses
The tubers are grown for sale or for food security. Some bitter yam varieties are
said to be very palatable. The bitter yam is solely used for ampesi .
Aerial or bulbil-bearing yam (D. bulbifera)
Ecology
Aerial yams are mostly found in annual cropping systems. They are planted
between March and May.
Land preparation and planting
Both freshly cleared and previously cropped lands are used. The crop is grown
in a mound or in a hole on the flat. The planting holes are 10-50 cm deep and
20-30 cm wide. Small whole tubers weighing 200-250 g or aerial bulbils are
used as planting materials. The sett is planted 10-15 cm deep and mounded over
with or without capping. The planting materials are usually nursed following the
techniques outlined for the other yams. Duration of nursing varies between three
and 12 weeks.
Staking
The crop is staked using the standard staking techniques described above.
Harvesting and storage
Aerial yams mature in nine months after planting. The bulbils are small, measur-
ing 1-9 cm in length with very smooth skin. Harvested bulbils are stored in barns
or stored covered under trees.
Maintenance and utilization
The aerial yam is maintained by yearly planting. The bulbils are boiled for ampesi .
The underground tuber is usually used only as a planting material.
Traditional methods of conservation of diversity in yams
in southern Ghana
With the exception of some white yam cultivars, notably bayere fitaa , puna ,
labrokor , and dundu banza , the bulk of the yams cultivated in the zone are heir-
loom varieties handed down for decades. Over the years the farmers have devel-
oped several strategies for ensuring the maintenance of these land varieties in
spite of uncertainties in the weather. Table 7.1 summarizes some of the strategies
employed.