Abstract
ABSTRACT: Exogenous ethephon and abscisic acid (ABA) treatments are used worldwide to improve the coloring of red table grapes, but there is little information about their impact on the quality of white grapes and wines. The aim of this work was to evaluate the effects of exogenous ethephon and ABA applications at veraison on the composition of ‘Verdejo’ white grapes, and on the quality of their wines. To attain this objective, a field trial was carried out in a ‘Verdejo’/110 Richter vineyard located in north-central Spain. Two levels of ethephon (0 and 1500 mg L−1) and ABA (0 and 800 mg L−1) were sprayed on clusters at veraison, in a factorial design for three consecutive seasons. Ethephon and ABA had additive effects, decreasing titratable acidity and increasing pH of the must, which could be exploited by accelerating the grape ripening process in cold-climate zones. Nevertheless, each growth regulator affected the composition and sensory analysis of the wines differently. Ethephon treatments produced wines with lower concentration of acids and better flavor quality than those made from untreated plants, while wines with ABA applications tended to have a higher ethanol concentration and poorer aroma quality than controls. The wines submitted to treatments with ethephon obtained the best overall evaluation in the sensory analysis throughout the trial.
Highlights
Growth regulators are chemicals, analogous to plant hormones in cellular activity, which are derived from both natural and artificial sources
Exogenous ethephon and abscisic acid (ABA) treatments are used worldwide to improve the coloring of red table grapes, but there is little information about their impact on the quality of white grapes and wines
Ethephon and ABA had additive effects, decreasing titratable acidity and increasing pH of the must, which could be exploited by accelerating the grape ripening process in cold-climate zones
Summary
Analogous to plant hormones in cellular activity, which are derived from both natural and artificial sources. A number of these products can promote the processes of synthesis and accumulation of substances during grape ripening, which help to reach maturity faster and improve the quality of the must (Cantin et al, 2007; Roberto et al, 2012; Szyjewicz et al, 1984). This is very significant under conditions of excessive vigor in the vineyard, especially in cool regions, where heat units for maturing fruit are frequently insufficient. Contradictory results have been noted in the effects of ethephon on the total solid content, pH, potassium and titratable acidity (TA) of must, depending on the cultivar tested, timing, concentration and application method (Szyjewicz et al, 1984)
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