Environmental Engineering Reference
In-Depth Information
essence of this practice, according to farmers, is to destroy termites and other
insects that attack yam tubers. Bullock-drawn ploughs are used to break the
land after the first rains. Raising of mounds, 0.4-0.6 m high, spaced 1.2-1.5 m
apart, follows this operation. According to farmers, soil suitability for yam cul-
tivation is evident in the presence of wild yam types in the area, which is an
indication of deep soils. Planting is done two days after the mounds are raised
and the planted seed-yam is mulched to reduce the soil water loss and protect
the seed-yam from solar radiation.
Two weeks after sprouting, the yam vines are either staked or not staked
depending on the yam type (Kranjac-Berisavljevic and Gandaa, 2000). Pricking
is done 10 weeks after sprouting. During a typical annual cultivation cycle, yam
is usually the last crop, before cassava, to be harvested.
Generally, harvested yam is stored in huts constructed from grass in the yam
farms. This allows ventilation and also minimizes losses through transporta-
tion. Another common practice among farmers is to carry the yams to their
homes where they are stored in a hut constructed with mud and roofed with
grass. In these huts, care is taken not to place the yam tubers on top of
each other.
Collection of yam types at Bongnayili-Dugu-Song PLEC
demonstration site
At Bongnayili-Dugu-Song, the main PLEC demonstration site in northern Ghana,
practising researchers and farmers work hand in hand on yam conservation and
multiplication, respecting each other's methods of gathering information while
reaching conclusions in a collaborative manner.
Twenty-two yam accessions from northern Ghana were analysed during 2001
with the help of PLEC researchers at the Crop Science Department of the
University of Ghana, Legon, using esterase and total protein banding patterns in
order to determine which of the yam types are similar to each other. The results of
these analyses are shown as Table 8.1 and Figures 8.1 and 8.2. Accessions num-
bered 1 and 4 in Figure 8.1 ( digi and laabako ) appear to be quite similar according
to esterase banding patterns, while accessions 5, 6, 7, 9, and 10 ( chamba , manchisi ,
kpuno , kan-gbaringa , and chenchito , respectively) appear to be virtually the same.
The same is true for accessions numbered 12, 16, and 18 ( zong , dakpani , and
goenyeni ), accessions 3 and 13 ( kpuringa and baamuyegu ), 14, 17, and 15 ( liilya ,
baayeri , and kiki ) and 19, 20, and 21 ( mogni-nyugo , gun-gonsalli , and nyuwogu ).
The dendogram presented in Figure 8.2 shows the links among yam types based
on total protein content. Yam type accessions numbered 13 and 19 ( baamuyegu
and mogni-nyugo ) and 20 and 21 ( gun-gonsalli and nyuwogu ) also appear the
same, while the accessions numbered 1 and 2 ( digi and bombe-tingye ), 7 and 8
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