INFLUENCE OF GA₃ ON GROWTH AND DEVELOPMENT OF ´THOMPSON SEEDLESS´ GRAPES (VITIS VINIFERA L.)

A field experiment was undertaken to study the influence of GA₃ treatments on growth and development of bunches and berries of ‘Thompson Seedless’ grapes (Vitis vinifera L.). The application of GA₃ (20, 25, 30 and 40 mg L^-1 concentrations) at 45, 50, 55 and 65 days, respectively, after October pruning to the bunches had significant effects on bunch length (23.84 cm), bunch breadth (13.26 cm), bunch weight (473.82 g), number of berries/bunch (112.00) and berry length (2.38 cm), when compared to non-treated bunches. A linear increase in the physical characteristics of the bunch was also observed with increasing concentrations of GA₃. Application of GA₃ at 20, 25, 30 and 40 mg L^-1 at 45, 50, 55 and 65 days after October pruning was found to be optimal in order to attain higher yields (5.53 kg/vine) and good quality of ‘Thompson Seedless’ grapes under Bangalore conditions. The number of berries per bunch decreased significantly in bunches treated with GA₃. This apparently indicated that the application of GA₃ at early stages of bunch development had a thinning effect.