## 3 Results and Discussion
### General Evaluation
Based on our findings, we propose that melatonin's effects on fruit quality are more nuanced than previously thought. The clear dose-dependent responses we observed suggest that standardized treatment protocols may need to be tailored to specific crop types and storage conditions. Melatonin (N-acetyl-5-methoxyryptamine) represents a naturally occurring multi-functional indolamine found extensively in plant species, synthesized from tryptophan, a rare amino acid in plant cells [51]. Its molecular complexity extends beyond a simple signaling molecule, functioning as a critical regulator in immune response, free radical scavenging, and cellular protection mechanisms. Importantly, from a food safety perspective, recent literature indicates a growing trend toward utilizing edible coatings and plant growth regulators in post-harvest research, driven by increasing consumer demand for natural preservation technologies [52]. Melatonin, emerging as a novel phytohormone, has garnered significant attention for its potential application in food preservation. Critically, toxicological assessments demonstrate promising safety profiles. In China, melatonin has been approved as a healthy food ingredient, while the United States Food and Drug Administration has classified it as a dietary supplement without documented severe side effects or toxicity concerns [53]. This regulatory recognition provides substantial scientific confidence in melatonin's potential application in food processing, particularly in fruit preservation strategies. Our study's findings not only corroborate these safety assessments but also highlight melatonin's potential as a natural, non-toxic alternative to traditional chemical preservatives in dried apricot processing. The concentration-dependent responses observed, particularly at 100 uM, suggest a nuanced approach to leveraging melatonin's protective capabilities while maintaining optimal food safety standards. Figure 2: Correlation matrix of physiological parameters in response to different melatonin concentrations. The intensity and size of circles represent correlation strength, while colors indicate correlation direction (blue for positive, red for negative correlation). Numbers show correlation coefficients (r) ranging from \(-\)1.00 to 1.00. Figure 4: Hierarchical clustering analysis of physiological parameters and their response to melatonin treatments. The color scale represents parameter values (red for high values, blue for low values). Dendrogram clustering on both axes reveals parameter associations and treatment similarities. Two main clusters separate oxidative stress markers (MDA, H\({}_{2}\)O\({}_{2}\), TFMM-Total Phenolic Content, DPPH, and CUPRAC) from quality parameters (color values and sugars), with sorbitol and \(\beta\)-carotene forming a distinct subgroup. Treatment clustering demonstrates clear separation between high (100 and 1000 uM) and low (Control and 10 uM) melatonin concentrations. Figure 3: Biplot analysis of the effects of different melatonin concentrations on physiological parameters. Vector length indicates the magnitude of variable contribution, while vector direction shows the relationship between variables. Treatment clusters demonstrate concentration-dependent effects of melatonin (Control, 10, 100, and 1000 uM) on measured parameters.