Gibberellic acid improves bunch weight and number of grape berries (Vitis vinifera L.), cv. Marroo Seedless, grown in the Andean valleys of Ecuador

The cultivation of grapes (Vitis vinifera L.) is increasing in the dry tropics and the Andean valleys of Ecuador. However, the quality of the bunch and berries of the 'Marroo Seedless' variety grown in the Valleys needs to be improved to compete with imported fruit. To this end, three experiments were carried out on 8-year-old plants to evaluate the dose and times of application of GA(3) (pre- and post-flowering), manual fruit thinning and branch ringing to increase bunch and berry size. A randomized complete block experimental design with four replicates was used. Bunch size and weight, number of berries per bunch and total soluble solids were evaluated. The results show that the application of GA(3) in pre-flowering (10 ppm) increases bunch length and diameter, while the larger equatorial, polar diameter and berry weight was achieved with two applications of GA(3) in post-flowering (40+20 ppm) or a single application with 100 ppm of GA(3). These results show that the application of GA(3) is a technology to improve the physical quality of the berries and grape bunches.