Madison, Wisconsin
July 18, 2007
 The
Yam bean originated where the Andes meet the Amazon and is
locally grown in South and Central America, South Asia, East
Asia and the Pacific. It is produced in three species which are
called the Amazonian, Mexican and Andean. Interbreeding of the
bean has resulted in fertile and stable hybrids. This gives it
potential to be reclassified as a single species, provide high
quality food production and offer a sustainable cropping system
that has been needed in Africa.
Researchers believe they have discovered a protein-rich starch
staple in the yam bean in Peru. They were previously considered
a root vegetable due to the high water content; however this
‘Chuin’ type has lower water content. Families living in the
area have been producing it as flour. The crop has extremely
high seed production, but its seeds contain high concentrations
of rotenone. This toxic compound has been used for reducing fish
populations and parasitic mites on poultry. Seeds are never
consumed since they are mildly toxic to humans and other
mammals. If the rotenone was removed from the seeds, they could
provide a strong protein source as well as seed oil profitable
in the food industry.
Séraphin Zanklan, a scientist at Centre Songhai in Porto-Novo
(Benin), has investigated the yam bean for its potential to grow
and produce food under West African conditions. The study was
funded by a scholarship from the German Academic Exchange
Service (DAAD). Thirty-four yam genotypes were grown with and
without flower removal at one droughty location and one
irrigated location. Of the 33 traits that were measured, nearly
all showed large genetic variation. This and the easy spreading
of its seeds, make the crops very desirable to breeders. Results
from the study will be published in the July-August 2007 issue
of Crop Science.
The study identified genotypes with high storage root
production. Flower removal increased storage root production by
50 to 100%. Several yam bean genotypes showed very low reduction
in storage root and seed production under drought stressed
conditions. As expected, the storage roots did show high protein
and starch contents. They have as much as three to five times
more protein than potatoes or yams. Most importantly, it was
found that storage roots can be processed into ‘yam bean gari.’
This is similar to the current staple of West Africa, ‘cassava
gari,’ a granular flour.
The bean could make a significant contribution to the
improvement of food support, especially where resources are
poor. The research is ongoing at the International Potato
Center, which has a mandate for the bean in the frame of Andean
Root and Tuber Crops. Further evaluation is needed on the range
of yam bean variations under different conditions. More
information on where they can be grown, their agronomic
potential and genetic diversity is important to determine the
types of breeding programs necessary for yam beans.
Crop Science,
http://crop.scijournals.org/ is a peer-reviewed,
international journal of crop science published bimonthly by the
Crop Science Society of America.
ASA,
CSSA and
SSSA are educational
organizations helping their 11,000+ members advance the
disciplines and practices of agronomy, crop, and soil sciences
by supporting professional development and science policy
initiatives, and by providing quality, research-based
publications, and a variety of member services. |
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