Optimizing Budburst and Yield in Superior Seedless Grapevines Using Supplementary Dormancy-Breakers

Gawish, M. S.; Mosallam, Marwa M.

doi:10.21608/jpp.2025.434460.1524

Optimizing Budburst and Yield in Superior Seedless Grapevines Using Supplementary Dormancy-Breakers

Document Type : Original Article

Authors

M. S. Gawish ¹
Marwa M. Mosallam ²

¹ Horticulture Department, Faculty of Agriculture, Damietta University. Damietta, Egypt.

² Department of plant production, Faculty of Environmental Agricultural Sciences, Arish University, North Sinai, Egypt.

10.21608/jpp.2025.434460.1524

Abstract

In this study, superior Seedless grapevines were pruned during the winter to retain 10 fruit canes (FCs), each with 10 buds. On 8^th of January, all vines were treated with a 5% hydrogen cyanamide (HC) spray, serving as the control treatment. For the four additional treatments, the vines received the same HC spray, supplemented by an additional dormancy-breaking agent (SDBA) applied on 16^th of January to the basal five buds of each FC to promote budburst. The SDBA treatments comprised either HC (2.5%), potassium nitrate (KNO₃; 2%), ammonium nitrate (NH₄NO₃; 2%), or zinc sulfate (ZnSO₄; 2%). By mid-March, shoot and cluster thinning was conducted to retain the six most vigorous shoots per FC and the largest 30 clusters per vine. The results indicated that all supplemental dormancy-breaking treatments enhanced budburst and bud fertility compared to the control (5% HC alone). These treatments also increased yield per vine and cluster weight. Furthermore, they significantly improved 100-berry weight, berry firmness, detachment force, juice TSS/acid ratio, leaf number per vine and per shoot, leaf-to-cluster ratio, as well as the length and thickness of new canes relative to the control.

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