Effect of endogenous gibberellins in the early stages of fruit growth and development of the 'Severianin' tomato

We investigated the effect of endogenous gibberellins on fruit growth of the 'Severianin' tomato. Uniconazole, an inhibitor of gibberellin biosynthesis, applied to parthenocarpic fruits at about 0, 1 and 2 weeks after anthesis reduces fruit weight, but given at about three weeks after anthesis has no effect. The effect of uniconazole was nullified by subsequent gibberellin application to the fruits, except when uniconazole was applied 3 d after anthesis and gibberellin 2 d later. In the seeded fruits treated with uniconazole no notable gibberellin activity was detected from 3 d to four weeks after treatment. These results suggest that endogenous gibberellins in the early phase are important for fruit setting and development.