Early Leaf Removal Increases Berry and Wine Phenolics in Cabernet Sauvignon Grown in Eastern Serbia

Miroslav Nikolic,Slavica Todic,Dejan Stefanovic,Ljiljana Kostic,Nina Nikolic

doi:10.3390/agronomy11020238

Abstract

Cluster zone leaf removal is a well-established viticulture practice for improving cluster microclimate and wine quality in cooler climates, while its efficacy in warmer conditions is less is known. Here we compared the effect of early (ELR, after fruit set; diameter of berries 3–5 mm) and late (LLR, beginning of veraison) leaf removal on berry composition and wine phenolic profile of grapevine (Vitis vinifera L.) variety Cabernet Sauvignon grown in a temperate, warmer region of Eastern Serbia. Compared to the control (no leaf removal), both leaf removal treatments increased the sugar content in fresh juice and alcohol concentration in wine. Over three consecutive years (2011–2013) markedly different in temperature and rainfall, ELR was clearly most effective in decreasing weights of cluster and of one berry, and in increasing of skin share in a berry. The content of total phenols, tartaric acid esters, anthocyanins, and flavanols in berry skin and wine was the highest in ELR treatment. ELR prominently modified the phenolic profile: Increasing flavanols, myricetin and quercetine in skin and wine, and anthocyanins, peonidin-3-glucoside in skin and delphinidin-3-glucoside in wine. This work demonstrated that early leaf removal positively influenced the chemical composition of berries and wine of Cabernet Sauvignon and might be recommended for practice in the temperate warm conditions.

Highlights

IntroductionCluster zone leaf removal ( termed as defoliation) is one of the most effective canopy management practices for altering microclimatic conditions surrounding the grape cluster (e.g., better aeration and sun light exposure of clusters, decreased humidity) and has shown to improve berry and wine quality [1,2]
Cluster zone leaf removal is one of the most effective canopy management practices for altering microclimatic conditions surrounding the grape cluster and has shown to improve berry and wine quality [1,2]
Grape yield ranged from 1.99 kg (ELR treatment in 2012) to

Summary

Introduction

Cluster zone leaf removal ( termed as defoliation) is one of the most effective canopy management practices for altering microclimatic conditions surrounding the grape cluster (e.g., better aeration and sun light exposure of clusters, decreased humidity) and has shown to improve berry and wine quality [1,2]. The modification of canopy microclimate and light exposure of clusters by leaf removal in the cluster zone showed the influence on the chemical and organoleptic properties of grapes and wines [3,4,5,6,7,8]. This effect mainly depends on the degree of leaf biomass removal, and on the timing [8,9]. Early leaf removal and subsequently increased cluster exposure to sun light, less affecting grape yield, increased berry sugar and phenolics, and maintained must acidity [8], but occasionally led to berry discoloration [13]

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Conclusion