University of Tabriz Journal of Plant Physiology and Breeding 2008-5168 16 1 2026 02 01 Effect of putrescine coating and cinnamon essential oil on the quality improvement of Washington Navel orange fruit 19 40 21234 10.22034/jppb.2025.69442.1387 EN Amin Mohebi Department of Horticultural Sciences, Faculty of Agriculture and Natural Resources, University of Hormozgan, Bandar Abbas, Iran. Rasool Etemadipoor Department of Horticultural Sciences, Faculty of Agriculture and Natural Resources, University of Hormozgan, Bandar Abbas, Iran. Mehrdad Babarabie Department of Agriculture, Minab Higher Education Complex, University of Hormozgan, Bandar Abbas, Iran. Journal Article 2025 10 01 <strong>Objective</strong>: Agricultural losses in fruits and vegetables during postharvest operations, storage, transportation, processing, and packaging are one of the main contributors to food waste. Washington Navel orange is one of the main varieties of oranges and an important economic citrus fruit worldwide. This study aimed to investigate the effects of putrescine polyamine and cinnamon essential oil on the postharvest life and quality of Washington Navel oranges.<br /><strong>Methods: </strong>This experiment was conducted as a factorial experiment based on a completely randomized design with three replications. The factors were: Cinnamon essential oil at the concentrations of 150 and 300 mg/L, putrescine at the concentrations of 0.5 and 1.5 mM, and three storage times (0, 30, and 60 days. On the first day of the experiment, the following characteristics were measured in this study: Ion leakage, fruit firmness, pH, titratable acidity, total soluble solids, total phenols, flavonoids, antioxidant capacity, and ascorbic acid content. In addition, after 30 and 60 days, the decay percentage, physiological weight loss, fruit firmness,<br /><strong>Results: </strong>The results of this study showed that treatment with cinnamon essential oil and putrescine reduced weight loss and softening, slowed decay rate, and preserved total soluble solids, titratable acidity, and pH in the oranges. Additionally, the tested treatments, by maintaining phenols, flavonoids, and ascorbic acid, increased the antioxidant capacity of the plants. The results showed that both putrescine treatments at three concentrations and cinnamon essential oil treatments at two concentrations had a positive impact on the storage life and postharvest quality of the oranges during a 60-day storage period, compared to the control treatment.<br /><strong>Conclusion: </strong>Among the treatments evaluated, the putrescine with the concentration of 1.5 mM and cinnamon essential oil with the concentration of 300 mg/L proved most effective. These findings demonstrate that natural and bio-based compounds can mitigate quality loss in oranges when the cold-chain control is limited. https://breeding.tabrizu.ac.ir/article_21234_5d08694b296e51d923a62a25f45a4494.pdf