The effects of the gibberellic acid applications to the seedless and fruit size of black myrtle (Myrtus communis L.

In this study, the effects of the gibberellic acid (GA3) treatments on seedless fruit formation and fruit quality in the black fruity myrtle (Yakup type) were investigated. The study was conducted between 2016 and 2018 in Antalya. 100 ppm of GA3 was applied to the all trees at the different stages of flowering. In control group, only distilled water was used. Pomological analysis of fruits obtained from the treatments within the scope of the project and total phenolic substance, flavonoid substance and antioxidant activity (ABTS) analyzes were performed. As a result of the research, all GA3 treatments reduced the number of seeds while the 1st, 2nd, 3rd, and 6th treatments reduced the fruit weight. Moreover, 2nd and 3rd treatments significantly reduced the number of seed from 9.95 pcs to 3.21 and 2.35 pcs respectively. Furthermore, 3rd treatment reduced the total seed weight of the fruits from 96.70 mg to 28.12 mg, and it reduced the rate of seed in the fruit from 14.99% to 5.32%. In the study, it was determined that GA3 treatments reduced the number of seed by inhibiting the pollen germination and pollen tube development. GA3 treatments did not affect the flower bud formation rate of the subsequent year. However, the treatments increased the rate of fruit casting and decreased the yield per tree. In addition, treatments decreased the total amount of phenolic and antioxidant activity of the fruits. In the study, 2nd treatment caused an increase in quercetin, epicatechin, myricetin, and benzoic acid contents. Besides, 2nd and 3rd treatments increased gallic acid, campferol, and routine contents.