Variations in phenolic levels in grapevine buds at eco-dormancy after chemically-induced stress conditions

Abstract

AbstractViticulture is one of the briskest economic activities worldwide. A major obstacle impeding such grape yields to satisfy the demand for increased production is the insufficient period of chilling temperatures which, due to climate change, is becoming briefer. The shorter period of cold leads to poor budbreak which, in turn, results in reduced yields. To combat this issue, agronomists have resorted to treatments with chemical regulators to meet the chilling requirement for bud dormancy release several fruit-bearing plants have, including grapevines.This study aimed at identifying and quantifying during eco-dormancy the individual polyphenolic compounds, and their possible variations, in the latent buds of the ‘Prime©’ and ‘Ralli’ table grape cultivars. The study induced chemical stress by means of four different solutions, at three discrete dates per year, for three consecutive years. Phenolics in the latent buds of the studied varieties were analyzed via HPLC. Their quantitative analysis showed variations both between the varieties and between the samples of those varieties collected after the eight treatments. The analysis indicated that the concentration of phenolics continued progressing during the annual growth cycle of the grapevine, with strong positive correlations being detected between catechin, epicatechin, chlorogenic acid, o-coumaric, piceid, procyanidins B1-B2, rutin, ε-viniferin. Luteolin registered a positive correlation with quercetin, resveratrol, o-coumaric, but not with the remaining polyphenols. The results confirmed that (a) the concentration of phenolics of the latent buds is affected by chemically-induced stress conditions, (b) depending on the date of application, significant changes appear in the variations of those phenolics.One sentence summaryChanges in the levels of polyphenol compounds of the grapevine’s latent buds hints, for the first time, how much stress the buds actually undergo under chemically-induced stress conditions