To find out the most suitable time for gibberellic acid application and its effect regarding the berry enlargement, soluble solids ,sugar/acid and pulp/peel ratios, an experiment was conducted at Isfahan Agricultural Experiment Station on a seedless (Askari) and a seeded (Mehreh) of grapes. GA3 was at concentrations of 0,20,40 and 80 mg/l to foliage before and after bloom.
Both application times produced larger berries and elongated clusters in both cultivars,but reduced the number of berries when applied before calyptera falls. Increasing CA3 concentration caused even greater cluster length still.
It is concluded that GA3 acts as a fruit thinning agent when applied at prebloom stage and as a berry elongater when applied post—bloom and cap fall stage.
)