الفهرس 
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Abstract
This study was conducted during two successive seasons of 2021 and 2022 on Flame seedless grapevines. The vines were grown at Afak farm located at Balat district, New Valley Governorate, Egypt. At the harvest date many of clusters were collected and selected for uniformity of size and shape and absence of visible defects and were directly transferred the laboratory of the Horticulture Department, Faculty of Agriculture New Valley University.
The collected clusters were divided into three similar groups. Each group (consisted of 18 clusters) was subjected to one of the following treatments:
1. Clusters were sprayed with salicylic acid 200 ppm pre-harvest (T1).
2. Clusters were sprayed with salicylic acid (200ppm) pre-harvest and immersed in S.A. at 200 ppm (T2)
3. Clusters were sprayed with salicylic acid (200ppm) pre-harvest and immersed in chitosan 1% (T3).
4. Clusters were sprayed with GA3 30 ppm pre-harvest (T4).
5. Clusters were sprayed with GA3 30 ppm pre-harvest and immersed in chitosan 1% (T5).
6. Clusters were sprayed with GA3 30 ppm pre-harvest and immersed in GA3 30 ppm (T6).
7. The control clusters were sprayed with distilled water and immersed in distilled water (T7).
8. The control clusters were sprayed with distilled water and immersed in chitosan 1% (T8).
The clusters of all treatments were dipped for 60 seconds in the solution of each treatment, dried, and then stored at 5±1°C in the refrigerator at 85-90% R.H until the end of storage period.
The clusters of each treatment were placed carefully in ventilated polyethylene bags each containing 3 clusters, to determine both weight loss and decay percentage, weekly intervals during the storage period. Each treatment was replicated 3 times (3 clusters of each).
The parameters of storage grape clusters were determined periodically at weekly interval as follow:
A-Physical properties:-
A-1 Weight loss%.
A-2 Decay%.
A-3 The weight of 100 berries
B-Chemical properties:-
B-1Total soluble solids percentage (T.S.S %)
B-2 Total acidity %
B-3 Total sugar %.
The obtained results could be summarized as follow:
Physical properties:-
Weight loss%:-
Generally, the weight loss significantly increased with the prolonging of storage period in the two successive seasons. Moreover, the maximum values of weight loss % were recorded at end of storage period for all treatments. The result showed also that the storage period of the control did not exceed three weeks, compared with the other treatments, which were longer than that. The highest percentage of weight loss was in the control, followed by T1: Salicylic spraying (T1) and GA3 spraying (T4) with significant differences between them in the first week, and T1 and T2 in both the second and third weeks with significant differences, and the lowest percentage was in GA3 spraying (spraying + chitosan dipping) (T5) and Salicylic (spraying + chitosan dipping) (T3), with significant differences compared with the other treatments in two successive seasons. On the other hand, the lowest percentage was in T3 and T5 with insignificant differences in the first season, but in the second season, the lowest percentage of the weight loss was in T5 only
Decay %:-
Generally, the percentage of decay gradually and significantly increased by the prolonging the storage period and reached its maximum values at the end this period for all treatments during both 2021 and 2022 seasons.
In the third week, the highest percentage of decay was found in the control (66.1, 73.8%) and sequenced with T4 (25.5, 28.1%) with significant differences, while the smallest percentage was in T3 (6.7, 6.1%) and T5 (2.2, 6.6%) with significant differences, respectively, in both study seasons. At the end of the storage period in the fifth week, two treatments only reached this period: T3 and T5. In the first season, the biggest percentage was in T5 (78.9%), and T3 was recorded at 54.1% with significant differences between them, while in the second season, there were insignificant differences between them that recorded T3 and T5 (26.1, 21.7%), respectively.
100 berries weight(g)
There was an inverse relationship between the weight of berries and the storage period; when the storage period increased, the weight of berries decreased, and this did so in two successive seasons.
The data proved that the treatments containing pre-harvest spraying with salicylic acid, or GA3, had higher values than the other treatments, including the control.
At the end of the storage period, just T3 and T5 were continued to the fifth week compared with other treatments. In the first season, T3 (168g) was higher than T5 (140.3g) with significant differences, while in the second season, there was an insignificant difference between them: T3 was 152.3 g and T5 was 146g.
Chemical properties:-
Total soluble solids percentage (T.S.S %):-
T.S.S content significantly increasing with extending the storage period and reached the maximum values at the end of storage period for all treatments during both experimental seasons.
At the end of the storage period, in the first season, T5 (25.6%) was higher than T3 (24.6%) with a significant difference, while in the second season, there was an insignificant between T3 (25.2%), and T5 (25%).
Total acidity %:-
Total acidity content gradually decreased for all treatments with the begging of storage period, and then it significantly increased and reached its maximum values at the end of storage period during both tested seasons. At the end of the storage period of both study seasons, the highest value was in T5 (0.66, 0.70%), and the lowest value was in T3 (0.57, 0.61%), respectively, with a significant difference.
Total sugar%:
At the end of the storage period, the data in the first season proved that there was an insignificant difference between T5 (17.6%) and T3 (17.2%), while in the second season, the data showed that there was a significant difference between T5 (18.9%) and T3 (18.2%).
Conclusion:
In light of the current results, it can be concluded that the best treatments are pre-harvest spraying with salicylic acid or GA3 and covering with chitosan, and it has reached the third week with good quality