الفهرس 
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Abstract
In Egypt, potato is considered one of the important vegetable
crops. It is present in the markets allover the year. A considerable
amount is exported abroad. It is cultivated mainly in two seasons
(summer and nili plantings). So, potato has to be stored in order to
be always present in the market. Hence, the study of the effect of
storage and the way-or ways-that could hinder or reduce the
deleterious effect of storage be very important. This study was
focused on the main characteristics that affect the quality of the
stored tubers. Of these are sprouting, loss in weight, chemical
contents [phenols, amino acids, sugars (reduced and nonreduced)].
The variety Alpha was chosen in this study as it is a
popular cultivar. The tubers of the summer planting suffer more
than nil i one during the growing season and also during storage for
the high temperature and humidity.
The experiment took 24 weeks (about 6 months) for each of
the summer and niIi planting and also four treatments were
considered in this investigation:-
• Control (tubers soaked in tap water for 5 minutes, well dried,
put in carton holed box for storage) .
• Tubers soaked in tap water for 5 minutes, well dried then
irradiated with gamma rays for 12 kilo-rad and then stored (as
the control).
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• Tubers put in calcium chloride solution (30/0) for five minutes,
dried then irradiated with gamma rays for 12 kilo-rad and then
stored .
• Tubers treated with calcium chloride for five minutes, dried,
c. irradiated with 12 k.rad, put in carton box etc.
This research took place In the Nuclear Research Center,
lnchas, Egypt.
Many important results were reached:
1. In general, storage has its negative effect on the potato tubers
from different points of view ”sprouting, loss of weight, the
chemical compounds”. Hence, the quality of the stored tubers is
affected.
2. Different treatments gave different results. For instance
sprouting existed in the stored tubers except those treated with
gamma radiation of 12 k.rad even alone or when accompanied
with the calcium chloride solution. The control or calcium
chloride solution (3%) gave nearly the same results even in the
summer or nili planting. Sprouting existed after 14 weeks of
storage for the summer tubers and after 16 weeks for the niIi
tubers.
3. At the end of the experiment, i.e. after 24 weeks the sprouting
percentage reached in the control of the summer planting
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13.95% and 12.99 with the calcium chloride treatment
(concentration 30/0). But for the ni Ii planting the control
exhibited higher sprouting percentage at the end of the
experiment (i.e. 24 weeks). This was 78.300/0 for the control and
77.31% for the calcium chloride treatment.
4. For the loss of tuber’s weight, all the stored tubers were reduced
in their weight. The loss was recorded two weeks from the
beginning of storage. The tubers of the summer season were
more affected than those of the nili season as the loss percentage
ranged from 4.5-37% after 24 weeks for the summer tubers and
4.4-30% for the nih tubers. Beside the loss percentage in tuber’s
weight is directly proportional with the storage time (duration).
5. The treatment with calcium chloride solution (3’%) was nearly
as that of the control. However, the application of gamma rays
(12 k.rad) even alone or with calcium chloride reduced this loss
about 5% than the control. This could assure the effectiveness of
gamma radiation (12 k.rad) as an important tool in this respect.
6. Clear increase was detected in the total free phenols in the first
three months of storage with the treatment of gamma radiation -
even alone or with calcium chloride solution 30/0 - in both
summer and nili plantings. Reverse effect existed during the
fourth to sixth months with the treatment of gamma radiation -
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even alone or with calcium chloride solution - i.e. reduction in
total phenols existed in both summer and nih tubers.
7. The control showed reduction in the total sugar content with the
increase of the storage period. However, the treatments included
gamma radiation the level of the total sugar was nearly constant
through the storage period. The treatment of calcium chloride
alone showed reduction in the total sugars through the storage
period. The previous mentioned results were more obvious in
the nili season. The reduction in the total sugars was mainly due
to the reduction in the reduced sugars in the first and the second
month. However, reduction in the total sugars afterwards could
c. be due to reduction in the non-reduced sugars.
Some differences existed in the total sugars in the summer
planting for instance some increase existed in the total sugars
with gamma rays application in the second, third and fourth
months. However, reduction took-place in the first and fifth
months.
In nil i tubers, reduction was detected in the total sugars with
the treatment of gamma radiation + calcium chloride in the sixth
month only. This reduction was due to the reduction in both
reducing and non reducing sugars.
8. The treatment of gamma radiation alone led to increase in the
stored tubers of the nih season in the first, second, fifth and
sixth months. Meanwhile, reduction in the total amino acids
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existed in the third and fourth months and through the storage
period (six months) in the summer season.
The treatment with calcium chloride alone caused increase
111 the total amino acids in the first months (1,2.3, 5 and 6) in
the nili season and in the months (I, 4 and 6) in the summer
season. Reduction in the amount of the amino acids existed in
the same treatment in the fourth month. in the nili tubers and the
second, third and fifth month of the summer tubers.
The treatment with gamma radiation + calci urn chloride
increased the total amino acids in all the months except the
fourth month as little reduction existed in the nih planting.
However, increase in this respect existed in the tubers of
summer plantings in the first and fourth month and reduction
existed in the other months by the same treatment.