Original scientific paper

The influence of basal defoliation at berry set on yield and phenolic composition of grapes of the ‘Merlot’ variety (Vitis vinifera L.)

Josipa Golenja ; Sveučilište u Zagrebu Agronomski fakultet, Zagreb, Hrvatska *
Marina Anić ; Sveučilište u Zagrebu Agronomski fakultet, Zagreb, Hrvatska
Mirela Osrečak ; Sveučilište u Zagrebu Agronomski fakultet, Zagreb, Hrvatska
Marko Karoglan ; Sveučilište u Zagrebu Agronomski fakultet, Zagreb, Hrvatska

* Corresponding author.

Abstract

Basal defoliation is a viticultural technique involving the removal of basal leaves with the aim of improving canopy aeration, reducing the incidence of microbial infections, increasing solar radiation in the cluster zone, and enhancing polyphenol synthesis. The study was conducted in 2020 in the Zagreb wine-growing region on ‘Merlot’ (Vitis vinifera L.). Basal defoliation was performed in the cluster zone at berry set. The effects of defoliation on yield, cluster weight, sugar content, total acidity, pH, and berry skin polyphenols were evaluated. The results showed that partial defoliation reduced cluster and berry weight but had no significant effect on yield per vine. Defoliation also reduced total acidity, while no significant effect on must sugar content was observed. Basal defoliation increased the content of flavonols, hydroxybenzoic acids, and flavan-3-ols, whereas no significant effects were observed on anthocyanins, hydroxycinnamic acids, stilbenes, or total polyphenols. These findings highlight the potential of partial defoliation as a canopy management practice for regulating grape yield and quality.

Keywords

grapevine; ‘Merlot’; basal defoliation; polyphenols; flavonols

Hrčak ID:

353305

URI

https://hrcak.srce.hr/353305

Publication date:

26.10.2026.

Article data in other languages: croatian

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