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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). ~~~~--~-------_ ..~- 6\ • 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 62 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 - 63 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 ----- --- ----_.~.- ----- ._------------ 64 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. |