Improving Yield and Bunches Quality of Sultana ‘H4 strain’ Grapevines

This study was carried out during the seasons of 2021-2022 to study the effect of GA 3 plus urea each alone or with trunk girdling and bunches tipping on yield and bunch quality of Sultana ‘H4 strain’ grapevines. The data reveal that spraying vines with GA 3 plus urea at the beginning of (15-20%) flowering significantly reduced the number of berries per bunch and the compactness coefficient of the bunch than the control. Furthermore, sprayed vines with GA 3 plus urea with both trunk girdling and bunches tipping significantly produced a higher bunch weight, berry weight, and size. Despite this, treated bunches with GA 3 plus urea gave no clear effect of SSC/acid ratio in berry juice than the control but increased the values of total chlorophyll a and b content in berry skin. Whereas, when girdling the trunk and tipping the bunch produced a higher SSC/acid ratio in berry juice and total carotenoid content in berry skin than the control.