Effects of gibberellic acid (GA3) and oxalic acid (OA) applications on fruit quality in Karyağdı pear (Pyrus communis L.) cultivar

This study was carried out in 2022 and 2023 in an indoor garden established with 7-year-old 'Karyağdı' pear variety grafted on BA 29 rootstock in Korkuteli district of Antalya province. The research was conducted to increase the recognition of this variety specific to Korkuteli district and to increase its share in the market and exports by improving its quality parameters. The experiment was created in a randomized plot design with three replications and 1 tree in each replication. In the research, different doses of Gibberellic Acid (GA3) (25 ppm) and Oxalic Acid (OA) [1 mM (0.09g/L), 2mM (0.18g/L), 3mM (0.27g/L), 4 mM (0.36g/L)] were applied to the trees of Karyağdı pear variety in the pre-harvest period and their effects on fruit quality parameters were examined. Phenological observations (buds emergence, bud burst, beginning of flowering, full bloom, end of flowering and harvest times) were made on trees of the 'Karyağdı' pear variety in the 2022 and 2023 trial years, independently of the trial. According to the applications, in addition to pomological measurements (fruit weight, fruit width, fruit length, fruit skin color and fruit firmness) in the harvested fruits, biochemical content analyzes (titratable acidity; TEA, pH, total soluble solid contents; SSC, vitamin C, total antioxidant activity, total phenolic substance amount and total flavonoid amount) were determined. The changes in the phenological observations occurred during bud swelling (18 March 2022, 20 March 2023), bud burst (25 March 2022, 29 March 2023), beginning (6 April 2022, 14 April 2023), full break (17 April 2022, 22 April 2023), end of burst (26 April 2022, 28 April 2023) and at harvest time (4 October 2022, 11 October 2023).. In the research; although there was no statistical difference from the 3 mM OA application in terms of fruit weight, fruit width and fruit length values, slightly higher values were obtained compared to the control group. In the study, the highest Vitamin C value was 3 mM OA (10.3 mg/100g), 25 ppm GA3 (8.6 mg/100g), control (8.3 mg/100g); total phenolic substance amount was 3mM OA (182 mg GAE/100 g), 25 ppm GA3 (134 mg GAE/100 g) and in the control application (128 mg GAE/100 g); antioxidant activity in 3 mM OA (2.91 mmol/kg), 25 ppm GA3 (2.40 mmol/kg) and control application (2.49 mmol/kg); The total amount of anthocyanins was obtained from 3 mM OA (10.17 mg/100 g), 25 ppm GA3 (8.36 mg/100 g) and control application (8.24 mg/100 g) respectively. As a result, it has been determined that the application of 3 mM OA may be important in the 'Karyağdı' pear variety due to its positive effects on improving fruit quality.