International Journal of Horticulture 2015, Vol.5, No.13, 1
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Table 1 Potato varieties used in the study
Potato cultivar
Source of original germplasm
Year of release in Kenya
Yield (ton/ha)
Maturity period (months)
Kenya Sifa
CIP
2006
35-45
3-4 (>110 days)
Pimpernel
Netherlands
1974
>40
4 (>120 days)
Roslin Tana
Scotland
1974
35-45
3-4 (>110 days)
Tigoni
CIP
1998
35-45
3-4 (>110 days)
Asante
CIP
1998
35-45
3-4 (>110 days)
Dutch Robjin
Netherlands
1945
35-40
3-4 (>110 days)
Desiree
Netherlands
1972
35-45
3-4 (>110 days)
Kenya Karibu
CIP
2006
35-45
3-4 (>110 days)
replicated three times. Each plot had five rows and
each row had 10 plants giving a total 50 plants per
plot. Plant spacing was 75 cm x 30 cm between and
within the row respectively. The crop was manged
according to the recommmendad practices for potato
production in Kenya (KARI, 2008) Source:Crissman
et al., 1993
After harvesting each replicate, the egg-sized tubers
(35-45 mm in diameter) were selected and samples of
5kg each were put in net bags; the net bags were
placed in crates in a diffused kight store (DLS). The
DLS had indirect light and ambient air conditions. It
was made of wood with wide open spaces between the
wood planks to allow in more diffuse light. In addition,
some iron sheets on the roof had been replaced with
transparent sheets to allow in more diffuse light. The
inner side of the DLS was lined with netting to keep
off insect pests and vectors. The floor was earthen to
prevent temperature build-up.
Similar triplicate samples of potatoes were put in
chitting crates and placed in a cold store (4
0
C and 95%
relative humidity). In both DLS and cold store, the
seed tubers were stored for a period of eight months.
Seed tubers from the cold store were placed at ambent
temperature three weeks before planting in the field.
The experiment was laid out as a split-plot design with
storage method (cold store and DLS) as the main
factor and the potato varieties as the sub plot.
The tubers were examined for tuber weight loss every
four week (during the first 16 weeks of storage) and
accepability of tubers as seed after the eight month
storage period. Acceptability of tubers as seeds is
mostly affected by firmness (opposite of shrinkage) of
the tubers after storage; the firmer the tubers were
after storage, the more acceptable they are. Four
panelists familiar with potato seed tuber quality used a
9-point scoring scale to evaluate the overall acceptablilty
of the seed. On this subjective scale a score of 1 was
the least acceptable while 9 was the most acceptable;
a score of 5.0 and above was acceptable.
After eight months of storage, the seed tubers were
planted out in the field at KARI-Tigoni during the
March-June long rains season of 2012. The experimental
design and crop management was as for the 2011.
Field data colected included plant emergence. During
harvest, data on tuber yield was taken from the middle
24 plants per plot.
Results and Discussion
Generally, Dutch Robjin experienced the least percentage
tuber weight loss under cold storage (Figure 1). In
addition, all varieties experienced significant (P≤0.05)
differences in percentage tuber weight loss among the
four evaluation times except for Dutch Robjin.
Roslin Tana had the highest tuber weight loss 16
weeks after storage in the DLS (Figure 2). There were
no significant (P≤0.05) differences in percentage tuber
weight loss after 8, 12 and 16 weeks of storage in
DLS for Kenya Sifa, Pimpernel, Tigoni, Asante and
Desiree.
For Kenya Sifa, Pimpernel and Asante, there was no
significant (P≤0.05) difference in percentage tuber
weight loss between cold store and DLS after 16
weeks of storage (Figure 3).
Most varieties were unacceptable as seed after eight
month storage under DLS (Figure 4). This could
probably be due to excessive shrinkage. Because DLS
was under ambient conditions as far as temperature
and relative humidity are concerned, it is possible that
the high air temperatures and low relative humidity
normally experienced between August and February
could have led to excessive shrinkage. In the contrary,
almost all potato varieties were acceptable as seed
after eight month storage in the cold room. This could
