الفهرس 
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Abstract
Grapes (Vitis vinifera L.) are one of the most important and widely cultivated fruit crops in Egypt. Since it ranks second after citrus in terms of cultivated area in Egypt. The total cultivated area reached about 172,533.6 feddans in Egypt with an annual total production of about 1,586,342 tons (FAO, 2020). Recently there are many new varieties planted in Egypt, which have found some problems that threaten their production and the continuation of their cultivation. One of the most important grape cultivars introduced for cultivation in Egypt is the Sultana ‘H4 strain’ grapevines, it is considered a new seedless cultivar with vigorous growth, yellow-green, and small to medium berries, clusters are large, conical, and compact. H4 is a strain of Sultana grapes that spread recently in Egypt and the expansion of its cultivation increased due to the higher production, in addition to its higher fertility rate than Thomson Seedless grapes. Sultana ‘H4 strain’ cultivar become one of the most important table grapes in local markets. Yet, high compactness of bunches and small size of berries are the most problem facing this cultivar, and this leads to a high percentage of moisture between berries and some of them in bunches as a result bunches become infected with fruit rot and thus this can cause a major loss in production and quality. Therefore, this study was carried out during the seasons 2021-2022 to evaluate the effects of using GA3 with urea alone or with girdling the trunk and tipping the bunch, each alone or in combination, in order to berry thinning and reduce bunch compactness to reduce infected with fruit rot as well as improve the quality of berries, bunches, and yield of Sultana ‘H4 strain’ grapevine during marketing. For the implementation of this study, thirty-six vines were selected as uniform as possible from the vines of Sultana ‘H4 strain’ grafted on Freedom rootstock on seven years old and grown in the vineyard of experiential field Horticultural Research Institute, Mansoura, Dakahlia Governorate, Egypt. The vines were grown in clay soil under a surface irrigation system, vines were planted at 2 x 3 meters using cane pruning by leaving 10 canes each of 12 eyes with 6 spurs, the total bud load was about 140-130 buds per each vine, under the Spanish Parron trellising system.