Effects of Pre-harvest Gibberellic Acid Application at Different Concentrations on Storability of ‘Obilnaja’ Japanese Plum

This study was carried out in a ‘Obilnaja' Japanese plum orchard in Manisa province of Turkey. Effects of pre-harvest gibberellic acid (GA3) applications on the quality changes of the plum fruits and post-harvest losses were researched. GA3 was applied at version stage as spraying onto the trees at 25 and 50 ppm concentrations. Untreated trees were considered as the control group. The fruits were harvested at firm harvest maturity stage and pre-cooled in modified atmosphere packages and then, packages were closed. Fruits were stored at 0oC and %90 relative humidity for 60 days. Sampling was done as pre-storage and after 30 and 60 days of storage and physiological, chemical and biochemical changes and physiological and pathological losses were monitored. Compared to control, fruit firmness was 17.3% higher in 50 ppm GA3 applied fruits at pre-storage period. However, this effect of GA3 did not continue till the end of the storage period. Fruit skin color, soluble solid content, titretable acidity, pH value, total phenolic contents and antioxidant activity of GA3 treated fruits were similar to the control group. After 60 days of storage, L* and b* values, acidity and fruit firmness decreased and fruit skin a* and pH values increased in storage of ‘Obilnaja' plum fruits compared to the initial storage period. Physiological and pathological losses did not occur during the storage. As a conclusion, the results showed that ‘Obilnaja' Japanese plum cultivar fruits can be stored for 60 days successfully under tested conditions.