engleski

Impact of cluster thinning on productive characteristics and wine phenolic composition of cv. Merlot

The effects of cluster thinning on productive characteristics and wine phenolic composition of a red grapevine variety Merlot (Vitis vinifera L.) was evaluated in this study. Cluster thinning consisted of removing upper clusters on shoots in order to remove 30% and 60% of clusters at veraison. Control treatment without cluster thinning was also applied. Two levels of cluster thinning reduced yield by 19% and 40%, respectively. Average cluster weight and leaf area/fruit weight ratio were increased and fruit maturity was advanced with cluster thinning. Wines produced from cluster thinned treatments had higher alcohol content, lower acidity, higher concentration of total phenolics, total anthocyanins and higher color intensity comparing to the control treatment. Cluster thinning affected not only the total anthocyanin concentration but also the anthocyanin profile in wines. It significantly increased the levels of delphinidin-3-monoglucoside, cyanidin-3-monoglucoside, petunidin-3-monoglucoside and peonidin-3- monoglucoside, while the concentration of the most abundant individual anthocyanin malvidin-3-monoglucoside and acylated anthocyanins did not differ considerably among treatments. The highest increase in the concentration of phenolic compounds occurred in the treatment with 60% of clusters removed. It was concluded that more than 1.5 m2 of leaf area per kg of fruit was needed for the production of high quality Merlot wine, which is especially adequate for aging due to high concentration of phenolic compounds.

cluster thinning; phenolics; anthocyanins; color intensity; Merlot

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