Environmental Engineering Reference
In-Depth Information
Conclusions
A survey carried out by the northern Ghana PLEC team in 2001 indicates that
about 75 per cent of farmers in Bongnayili-Dugu-Song, the main PLEC
demonstration site in northern Ghana, cultivate yam. On an average, about five
yam types are found on every yam farmer's field. Farmers are able to supply
information on the traditional methods of yam domestication, characteristics
of the crop such as colour, leaf, stem, and tuber, and also on the usefulness of
particular yam types in terms of storability and taste. Farmers have many
reasons for growing certain yam types. The reasons range from spiritual to
commercial. It is also observed that some yam types growing in the wild are
indicators of soil fertility.
The farmers provided the PLEC research team with a yam plantation site where
all the collected 22 northern yam types were planted for further observations.
During the 1999-2001 rainy seasons, 22 yam types were identified and col-
lected by farmers. Detailed information on the morphological characteristics and
nutritional value of the yam types is now available.
Chemical analysis carried out in 2001 show that the yam types in northern
Ghana have a very low protein content. The protein content ranges from 1.6
per cent (
manchisi
) to 4.1 per cent (
kan-gbaringa
). Similarities and differences
among the 22 yam types, based on the esterase and total protein banding patterns,
are also available.
Phosphorus level content for the same types ranged from 29.2 mg/100 g (
gun-
gonsalli
) to 3.8 mg/100 g (
kukulga
), and iron content ranged from 11.1 mg/100 g
(
zong
) to 0.5 mg/100 g (
gun-gonsalli
,
friginli
,
baamyegu
,
digi
,
kpuringa,
and
liilya
). Calcium content ranged between 30.5 mg/100 g (
gun-gonsalli
) and
6.3 mg/100 g (
baayeri
). These values are far in excess of the values reported in
the literature by other authors.
Variability and disparity in all the results indicate that much more work needs
to be done in order to obtain a clearer picture on nutritional values, genetic rela-
tionships, and other characteristics of various traditional yam types cultivated in
northern Ghana.
Further collaborative studies are planned to compare the varieties cultivated in
northern Ghana with those grown in the other parts of the country, notably the
Sekesua-Osonson PLEC demonstration site in southern Ghana (see Chapter 7).
REFERENCES
Blench, R., “Neglected species, livelihoods and biodiversity in difficult areas: How should
the public sector respond?”,
ODI, National Resources Perspectives
, Vol. 23, 1997,
pp. 1-4.
