الفهرس 
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Abstract
The present study was carried out during three successive seasons 2018/2019, 2019/2020 and 2020/2021 to investigate the effect of Paclobutrazol, Gebrilic acid, and Ethrel on the behavior of superior grapevines. For achieving the previous goal 54 vines grown in Talla district- Minia Governorate were selected and devoted to the present study. Vines were six years old planted at (1.5 x 3.0) meters apart and trained as gabble supporting system. Pruning was carried out annually at the first week of January to leaves 96 buds per vine on the basis of eight fruiting canes with ten buds plus eight renewal spurs x two buds.
All the selected vines (54 vines) received the standard horticultural practices provided in the vineyard, which included the use of 10 m3 farmyard manure, N 0.35 %, 200 kg ammonium nitrate, N 33.5%, 150 kg calcium superphosphate, P2O5 15.5%, and 200 kg potassium sulphate, K2O 48 % per one feddan yearly. The addition of one batch of farmyard manure was applied in Mid-January. Along with adding farmyard manure, phosphate fertilizer was also applied once. Fertilizer containing potassium was added twice at the start of growth and once after berry emergence. Three varying dosages of ammonium nitrate fertilizer were applied: 40 % at the beginning of growth (first week of March), 40 % after fruit set (first week of April), and 20 % at one month after harvest. The typical horticultural procedures were followed, including watering, pinching, howling the soil (twice a year after winter pruning and again after berry setting), and pest resistance.
The main obtained results can be presented in the following points:
• Paclobutrazol had reduced the length of shoots and leaves and the overall number of leaves on plants and improve the quality of berry. Paclobutrazol application greatly slowed the pace of vegetative development. An impact on yield that was accompanied by an increase in the size, quantity of fruit on the plant and improvement quality of superior grapevine when using Paclobutrazol in concentration (1000 ppm).
• In the light of pervious results one can state that GA3 was effective in increasing the cluster weight and yield, delaying the ripening of grape clusters, and thus prolonging the period of harvesting the crop and obtaining it for long periods of time.
• Using Ethrel at 400 ppm it was hastened the maturation date, T.S.S % , total sugars % , T.SS/acid of the grape superior grapevines.
• The quality of the grapes was maintained by all treatments as compared with the control through increasing total soluble solids and reducing sugars in the same time reducing the acidity.