Abstract

Background and Aims Red tablegrapes may fail to develop adequate berry colour. To correct this, abscisic acid and ethephon are applied; however, little is known about the possibility of brassinosteroids (BRs) to improve berry colour. Thus, a commercial BR formulation was tested in two commercial vineyards of Redglobe and Crimson Seedless in order to evaluate its effectiveness for improving berry colour. Methods and Results Treatment at a concentration of 0.06 mg/L was applied only one time at veraison or the application was repeated 7 days later. Anthocyanin concentration, berry colour [evaluated as colour index for red grape (CIRG)] and other berry quality parameters were evaluated. Treatment with BR increased anthocyanin in the berries of both cultivars. As a result, a higher CIRG was observed in Redglobe treated berries, whereas in Crimson Seedless the CIRG was similar to that of the Control, despite an increase in berry size generated by the BR treatment of this cultivar. Conclusions The commercial formulation tested improved the colour of Redglobe berries and maintained the colour in the resulting larger berries of Crimson Seedless. Significance of the Study This study supports the potential of BRs as a tool to improve berry colour in a commercial context, laying the foundations for future work and incorporation of BRs within tablegrape management programs.