Abstract
The effects of treatment with gibberellin and MnSO4 solution on berry splitting in ‘Delaware’ grape were investigated. The density of berries in a bunch treated with the first gibberellin (GA, 100 ppm) dipping at the 7~8 leafing stage decreased by 0.5~2.3 berries·cm−1 compared to that at the 9~10 leafing stage. However, GA treatment appeared to have no suppressive effect on berry splitting due to the lack of calyptra shedding, low level of surface wax adhesion, and low degree of pericarp intensity. For the prevention of berry splitting, bunches of berries that still contained many non-removed calyptras demonstrated both an increase in surface wax adhesion and decrease in berry splitting. This was achieved by a second GA (100 ppm) treatment 5 days after full blooming and a double MnSO4 solution treatment: MnSO4 (0.5-1.0%) simultaneously with the first GA treatment and MnSO4 (0.5-1.0%) just before full blooming. Correlations between the level of adhesion of surface wax and the intensity of pericarp or percentage of berry splitting were positive and negative, respectively.
