Abscisic Acid and Ethephon for Improving Red Color and Quality of Crimson Seedless Grapes Grown in a Tropical Region

Abstract

This study sought to examine the effects of applying abscisic acid (ABA) and ethephon at different rates and times on color properties and quality of Crimson Seedless grapes grown in the Sao Francisco River Valley, Brazil. The experiments were carried out over three growing seasons (i.e., production cycles) in a commercial vineyard in Petrolina, Pernambuco State. The treatments consisted of a control (without ABA or ethephon), ethephon alone or with ABA, and ABA applied at 400 and 600 mg/L. ABA was tested in four different applications: a single application of ABA at veraison 90 to 97 days after pruning (DAP); two applications of half the application rate, the first one at veraison or berry softening (90 to 97 DAP) and the second at 17 to 20 days postveraison (DPV); a single application at 17 to 20 DPV; and ABA at 200 or 300 mg/L combined with ethephon. Application of ABA and ethephon did not influence yield, cluster weight, berry diameter, skin elasticity, soluble solids, or sugar content. Titratable acidity was influenced by application of 200 mg/L ABA at 90 DAP and 17 DPV but only in the first production cycle. Flesh (pulp) firmness was affected only in the third cycle by ethephon alone or when combined with 300 mg/L ABA. In 2012, ethephon application combined with 200 or 300 mg/L ABA at veraison (97 DAP), resulted in berries with significantly darker skin color, lower lightness (L*), and a higher b* value, indicating more advanced maturation. In all three production cycles, ABA and ethephon application increased anthocyanin content, resulting in a darker red berry color; the magnitude of this response varied among the cycles.