The objective of this study was to evaluate the effect of different concentrations of gibberellic acid (AG3), thidiazuron (TDZ) and forchlorfenuron (CPPU) on the size of bunches and berries and on the total soluble solids content, when applied in different concentrations on the seedless grapes, cv. BRS Clara. The grapevines were grafted on the rootstock IAC 572, trained in the pergola system and, spaced 2.5 x 2.0m and irrigated by micro sprinklers. The experiments were carried out at the Embrapa Grape and Wine Experimental Station for Tropical Viticulture in Jales, SP. The bunches were directly sprayed with the plant growth regulators, either individually or combined, in concentrations from 0 to 4mg.L-1 of CPPU; 0 to 10mg.L-1of TDZ and 0 to 90mg.L-1 of AG3. Generally, the application of growth regulators improved the quality of the bunches of the cv. BRS Clara; the use of TDZ and CPPU, combined with AG3, produce a synergistic effect, causing a better response than the isolated use of AG3; the treatments with 60mg.L-1 of AG3, 20mg.L-1 of AG3 + 4mg.L-1 of CPPU and 10mg.L-1 of AG3 + 5mg.L-1 of TDZ provide the best results for increase in the berries diameter; the application of AG3 before flowering cause excessive abortion which reduced the commercial value of the bunches. High concentrations of plant growth regulators decrease the content of total soluble solids.
Vitis sp.; table grape; gibberellic acid; thidiazuron; forchlorfenuron
