# Unveiling the Synergistic Effects of Melatonin, Arginine, and Nano‐Chelated Zn‐Fe on Enhancing Fruit Quality in Apricot (Prunus armeniaca)

## TL;DR

This study shows that combining melatonin, arginine, and nano-chelated zinc-iron improves apricot fruit quality and yield.

## Contribution

The novel contribution is identifying specific synergistic treatment combinations that significantly enhance apricot fruit traits.

## Key findings

- Arginine 150 ppm + melatonin 400 μmol/L + Zn-Fe nano-chelate 2 and 3 g/L increased fruit firmness, weight, and yield.
- These treatments improved vitamin C, soluble sugars, and mineral concentrations in apricot fruits.
- The treatments also enhanced leaf area and chlorophyll content while reducing acidity.

## Abstract

Apricot (
Prunus armeniaca
) is a delicious and highly nutritious fruit, rich in organic acids, various vitamins, sugars, proteins, and minerals, and possesses multiple medicinal properties. To enhance fruit yield and quality while reducing the use of chemical fertilizers, an experiment was conducted on the basis of a randomized complete block design with three replications in the north of Dohuk, Iraq during 2023. Apricot trees were foliar‐sprayed with 28 different combination levels of arginine, melatonin, and nano‐chelated zinc–iron. The results showed that most treatments led to improvements in both quantitative and qualitative traits of apricot fruits compared to control. Among them, the application of arginine 150 ppm + melatonin 400 μmol/L + Zn‐Fe nano‐chelate 2 and 3 g/L resulted in the most significant increases in fruit firmness (21.14% and 21.93%), fruit weight (35.60% and 35.35%), fruit length (25.77% and 20.26%), fruit yield (27.11% and 26.95%), the contents of vitamin C (20.73% and 20.39%), soluble sugars (33.51% and 33.58%), and total soluble solids (17.60% and 17.72%) compared to control. These treatments also improved the concentrations of calcium (49.26% and 47.84%), magnesium (20.97% and 26.36%), potassium (58.40% and 67.43%), zinc (11.19% and 19.26%) and iron (9.46% and 11.07%) in the fruit, while reducing total acidity. In addition, they enhanced leaf area and chlorophyll content (SPAD index). Ultimately, these two treatment combinations are recommended for improving both the quantity and quality of apricot production.

Highest levels of mineral materials and vitamins were observed in arginine (150 ppm) + melatonin (400 μmol/L) + Nano‐chelated Zn‐Fe at either 2 or 3 g/L. T27 and T28 resulted in the highest fruit yield, total soluble solids, fruit set, and firmness, along with reduced acidity. 150 ppm + 400 μmol/L + 2 g/L and 150 ppm + 400 μmol/L + 3 g/L are recommended as the most effective for enhancing yield and fruit quality.