Application time and concentrations of abscisic acid on the color development of 'Isabel' grapes

Abstract

The grape 'Isabel' main cultivar used for juice production in Brazil has a deficiency of coloring and an alternative is the application of abscisic acid (S-ABA), since the accumulation of anthocyanins, pigment that interferes in the color of berries, appears to be regulated by this growth regulator. The aim of this research was to evaluate the effect of different concentrations of S-ABA applied at different times in the clusters of 'Isabel' grapes to improve their color attributes. The vines were conducted in a vertical support structure, spaced 2 x 1 m in cordon. A randomized block design was used as a statistical model, with 4 replications and 5 treatments, as follows: control; S-ABA 200 mg L-1 applied seven days after veraison (DAV); S-ABA 400 mg L-1 7 DAV; S-ABA 200 mg L-1 7 DAV +S-ABA 200 mg L-1 10 days before harvest (DBH); S-ABA 400 mg L-1 7 DAV + 400 mg L-1 10 DBH. At harvest the following variables were evaluated: mass and diameter of the berries, mass and length of the clusters; soluble solids (SS), titratable acidity (TA) and maturation index (TSS/TA). It was also evaluated the concentration of anthocyanins and total polyphenol index in wine and juice, prepared by the extraction method of the pan and color of the berries by colorimetry. The application of S-ABA did not influence the physical characteristics of the grapes, however, favored the increase of SS and SS/TA of the berries, except for the concentration of 200 mg L-1 applied seven days after veraison. The S-ABA has an effect on improving the content of anthocyanins of the berries and the juice of the 'Isabel' grape, mainly in the 400 mg L-1 applied 7 DAV + 10 DBH, besides enabling the improvement in the color attribute of berries.