CHAPTER ONE
INTRODUCTION
African Yam Bean (AYB) (Sphenostylis stenocarpa Ex. A. Rich, Harms) is an
underutilized food leguminous crop of the family Fabaceae, sub family
Papilionoideae (Azeke et al., 2005; Moyib et al., 2008). The domestication,
cultivation and distribution of the crop are very evident in the tropics and Africa
where it had been reported to exhibit very high diversity (Okpara et al., 1997).
The distribution of the crop according to Genetic Resources Information
Network (GRIN), (2009), includes the following countries within the tropical
regions of Africa: Chad and Ethiopia (Northeast tropical Africa); Kenya,
Tanzania and Uganda (East tropical Africa); Burundi, Central African Republic
and Democratic Republic of Congo (Central tropical Africa); Cote d’voire,
Ghana, Guinea, Mali, Niger, Nigeria and Togo (West tropical Africa) etc.
Nigeria is very significant in AYB production where extensive cultivation had
been reported in the Eastern, Western and Southern areas of Nigeria (Saka et al.,
2004). AYB thrives in weathered soils where the rainfall can be extremely high.
It grows well even in acidic and highly leached sandy soil of the humid low land
tropics (Uguru et al., 2001).
The plant is an annual, with climbing, vine-like stems that require staking; the
stem is often reddish in colour. In Nigeria, it is usually grown in association with
yams, maize, cassava, etc., so that the same stake of the yam serves as support
for both crops. It is cultivated mainly for home consumption and only about 30%
of the dry grain produced is sold. It is also planted for soil restoration (Saka et
al., 2004). The seed is planted at the base of yam mounds in June or July.
Germination is hypogeal and takes about 5 days after planting. It begins
flowering at about 80-120 days and set fruits from late September and October.
The large bright coloured (purple) flowers result in long linear pods that could
house about 20 seeds and they vary in size, shape, colour, etc. Pods start
maturing about 150 days after sowing. The tubers which develop more slowly
than the flowers, normally take 5 to 8 months to swell to harvestable size. Most
are dug up towards the end of the rainy season. AYB seeds
INTRODUCTION
African Yam Bean (AYB) (Sphenostylis stenocarpa Ex. A. Rich, Harms) is an
underutilized food leguminous crop of the family Fabaceae, sub family
Papilionoideae (Azeke et al., 2005; Moyib et al., 2008). The domestication,
cultivation and distribution of the crop are very evident in the tropics and Africa
where it had been reported to exhibit very high diversity (Okpara et al., 1997).
The distribution of the crop according to Genetic Resources Information
Network (GRIN), (2009), includes the following countries within the tropical
regions of Africa: Chad and Ethiopia (Northeast tropical Africa); Kenya,
Tanzania and Uganda (East tropical Africa); Burundi, Central African Republic
and Democratic Republic of Congo (Central tropical Africa); Cote d’voire,
Ghana, Guinea, Mali, Niger, Nigeria and Togo (West tropical Africa) etc.
Nigeria is very significant in AYB production where extensive cultivation had
been reported in the Eastern, Western and Southern areas of Nigeria (Saka et al.,
2004). AYB thrives in weathered soils where the rainfall can be extremely high.
It grows well even in acidic and highly leached sandy soil of the humid low land
tropics (Uguru et al., 2001).
The plant is an annual, with climbing, vine-like stems that require staking; the
stem is often reddish in colour. In Nigeria, it is usually grown in association with
yams, maize, cassava, etc., so that the same stake of the yam serves as support
for both crops. It is cultivated mainly for home consumption and only about 30%
of the dry grain produced is sold. It is also planted for soil restoration (Saka et
al., 2004). The seed is planted at the base of yam mounds in June or July.
Germination is hypogeal and takes about 5 days after planting. It begins
flowering at about 80-120 days and set fruits from late September and October.
The large bright coloured (purple) flowers result in long linear pods that could
house about 20 seeds and they vary in size, shape, colour, etc. Pods start
maturing about 150 days after sowing. The tubers which develop more slowly
than the flowers, normally take 5 to 8 months to swell to harvestable size. Most
are dug up towards the end of the rainy season. AYB seeds
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