CHEMICAL AND NUTRITIONAL RESPONSE OF TWO LOCAL APRICOT VARIETIES (ZANJILI AND ZAGNIA) TO FOLIAR APPLICATION OF NUTRIENTS AND MELATONIN

Abstract

This study was conducted in a private orchard in Diyala Governorate, Iraq, on eight-year-old apricot trees of the Zanjili and Zagnia varieties, during the 2024 and 2025 growing seasons, with the aim of demonstrating the response of the chemical and nutritional composition of the fruits of the two varieties to foliar spraying with nutrients (calcium oxide at a concentration of 20 g L⁻¹, boron at a concentration of 300 mg L⁻¹, and sorbitol at a concentration of 30 g L⁻¹) and melatonin at three concentrations (0, 50, 100 mg L⁻¹). The experiment was conducted using a split plot design within a randomized complete block design (RCBD) as a factorial experiment with three factors and three replications, with 72 experimental units. The results were analyzed using the SAS statistical software, and the means were compared according to Duncan's multiple range test at a probability level of 0.05. The results showed that the Zagnia variety was significantly superior in the percentage of total soluble solids, total sugars, their ratio to acidity, total phenols, and the boron content of the fruit, while the Zanjili variety was superior in the sorbitol and vitamin C content of the fruit and the higher acidity percentage. No significant difference was found between the two varieties in the carotene content of the fruit peel. The sorbitol spray treatment was characterized by its clear superiority in most of the fruit's chemical properties (soluble solids, total sugars and their ratio to acidity, total phenols, vitamin C, carotene, and the fruit's sorbitol content itself). The boron spray treatment was superior in increasing the fruit's boron content, while the calcium oxide spray treatment was superior in increasing the fruit's calcium content. Spraying with melatonin at a concentration of 100 mg/L⁻¹ resulted in the highest values for most of the studied chemical properties and the lowest acidity, followed significantly by a concentration of 50 mg/L⁻¹. The no-spray treatment yielded the lowest values and the highest acidity. The results of the three-way interaction showed that the Zagnia variety, treated with sorbitol and melatonin at a concentration of 100 mg/L, exhibited superiority in most of the fruit's chemical properties (soluble solids, sugars and their acid-to-sugar ratio, and phenols). The Zanjili variety, treated with sorbitol and melatonin at a concentration of 100 mg/L, showed superiority in vitamin C, carotene, and sorbitol content. The Zagnia variety, treated with boron and melatonin at a concentration of 100 mg/L, showed superior boron content in the fruit, while the Zanjili variety, treated with calcium oxide and melatonin at a concentration of 100 mg/L, showed superior calcium content in the fruit. This confirms a clear synergistic effect between the variety, the nutrients, and melatonin in improving the chemical and nutritional composition of the two studied apricot varieties.