Seed Formation is Affected by Uniconazole, an Inhibitor of Gibberellin Biosynthesis, in a Parthenocarpic Cultivar Severianin of Tomato (Lycopersicon esculentum Mill.)

In order to increase seed production of a pat-2 parthenocarpic tomato cultivar, we attempted to enable fertilization by applying an inhibitor of gibberellin (GA) biosynthesis to the whole plant to prevent pseudoembryo formation prior to anthesis. The pat-2 parthenocarpic tomato cultivar ‘Severianin’ was cultured with hydroponics, and the GA biosynthesis inhibitor, uniconazole-P, (E)-(S)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pent-1-en-3-ol, was added to the culture solution at 0, 0.01, 0.05, and 0.25 mg·L-1 about two weeks before the first flower anthesis. Stigmata were removed to prevent pollination from half of the plants of each concentration before anthesis, and the other half were tapped by a finger at anthesis for pollination. For pollinated fruits, there were no differences in fruit weight and seed number between the different concentrations of uniconazole-P. A significant positive correlation was observed between seed number and fruit weight in pollinated fruits treated with uniconazole-P that was not observed in the absence of uniconazole-P. There were no significant differences in the germination rate at any concentrations tested compared to the control. Seedlings grown from uniconazole-P-treated plants appeared to develop normally and did not differ from the control. Hence, uniconazole-P treatment of the whole plant was useful for increasing the efficiency of seed production for a parthenocarpic pat-2 cultivar. This was augmented by choosing large fruits at harvest, which contain sufficient amounts of true seeds based on the strong positive correlation between seed number and fruit weight.