Regulation of Quality and Phenolic Metabolism in Apricot Fruit by Postharvest Salicylic Acid and Putrescine Applications

Apricots are a highly sensitive product that suffers rapid quality losses due to physiological and biochemical processes such as increased respiration, ethylene production, cell wall breakdown, and changes in phenolic compounds that occur in the post-harvest period, and this significantly shortens their shelf life. This study evaluated the effects of salicylic acid (SA) and putrescine (Put) applications on post-harvest quality characteristics, organic acid metabolism, and phenolic compound stability in apricot (Prunus armeniaca L.) fruits. Fruits harvested at commercial maturity were treated with four different applications: control, SA (1 mM), Put (1 mM), and a combination of SA and Put. In this study, the physiological quality parameters such as weight loss, decay rate, soluble solids content (SSC), titratable acidity (TA), pH, and respiration rate were measured, and biochemical analyses of organic acids and individual phenolic compounds were performed. With increasing storage time, weight loss, decay rate, and pH values increased in all treatment groups, whereas significant decreases occurred in organic acids, ascorbic acid, and total phenolic compounds. However, it was determined that SA and Put applications significantly slowed down these negative changes. In particular, the SA + Put combination improved storage stability by providing the lowest weight loss and decay rate thanks to the preservation of cell membrane stability and the limitation of transpiration. Phenolic compound analyses showed that phenolic degradation is the natural process during storage, but SA and Put applications significantly slowed this process. In particular, it was determined that the combination application contributed to the preservation of antioxidant phenols by supporting phenylpropanoid metabolism, and that the highest level of phenolic stability was achieved in this group. PCA results revealed that quality degradation parameters were positively correlated with respiration rate and weight loss, whereas phenolic compounds, organic acids, and ascorbic acid showed strong positive correlations with quality preservation. Correlation analysis also supported these findings, confirming that antioxidant compounds play a decisive role in storage performance. In conclusion, it was determined that the combined application of SA and Put reduces oxidative stress, regulates metabolic activity, stabilizes phenolic metabolism, and significantly delays post-harvest quality losses in apricot fruit. This approach was found to offer an effective, feasible, and sustainable post-harvest strategy for extending shelf life and preserving nutritional quality components.