Application timing and concentration of abscisic acid improve color of ‘Benitaka’ table grape

Abstract

‘Benitaka’ is one of the most important colored table grapes grown in Brazil. However, the lack of a pink and uniform color of berry skins is frequently observed when this cultivar is grown in warm climates, where high temperatures may inhibit anthocyanin accumulation. The endogenous plant growth regulator, abscisic acid (S-ABA), the concentration of which increases in grape berry skins at the onset of maturation (veraison), seems to be involved in the regulation of anthocyanin accumulation. Recently, an efficient S-ABA production method was developed so that it could be used on crops, which led to the evaluation of different concentrations applied at or around veraison to colored table grapes. Thus, a trial was carried out during two consecutive seasons in a commercial vineyard of ‘Benitaka’ table grape trained on an overhead trellis system, located at Marialva, Paraná state, Brazil. A randomized complete-block design was used with vines as blocks and clusters as experimental units, with four replications and eight treatments, as follows: (a) control; (b) S-ABA 200mg/L applied 7 days after veraison (DAV); (c) S-ABA 400mg/L 7 DAV; (d) S-ABA 200mg/L 15 days before harvest (DBH); (e) S-ABA 400mg/L 15 DBH; (f) S-ABA 200mg/L 7 DAV+200mg/L 15 DBH; (g) S-ABA 400mg/L 7 DAV+400mg/L 15 DBH; (h) ethephon 500mg/L 7 DAV. In both seasons, S-ABA improved the color of ‘Benitaka’ grapes, especially when it was applied twice, i.e., 400mg/L 7 days after veraison and 400mg/L 15 days before harvest. Regardless of the concentrations or application timing, there is no alteration in the berries and clusters physical characteristics.