Effects of Gibberellin Inhibitors on the Fruit Set Rate and Ovule Degeneration in Sweet Cherry (Prunus avium L.)

Abstract

Fruit set of sweet cherry becomes unstable with high temperatures in the flowering period. High temperatures during the flowering period increase the concentration of endogenous gibberellin-like substances of the floral organs. Degeneration of the ovule is accelerated by gibberellin. Since endogenous gibberellin affects ovule degeneration, the authors focused on the action of a gibberellin biosynthesis inhibitor. Treatment with a gibberellin biosynthesis inhibitor was examined to determine whether stable fruit set can be obtained even when high temperatures are encountered during the flowering period. The fruit set rate of the section treated with a gibberellin biosynthesis inhibitor was significantly higher than that of the untreated plot. The effects on shoot elongation depend on the type of gibberellin biosynthesis inhibitor used; the plant regulatory agent with the mildest impact was prohexadione calcium. Since prohexadione calcium has a small influence on shoot elongation, we examined the effect on open field cultivation. Even if cherry blossoms encounter high temperatures during the flowering period, it is possible to maintain healthy ovules for longer by processing prohexadione calcium up to 2 weeks before flowering. Additionally, it was revealed that the fruit set rate was improved compared with the untreated plot.