Effects of chitosan and melatonin applications on leaf nutrient contents in sweet cherry cultivars

This study was conducted to investigate the effects of chitosan and melatonin applications on leaf nutrient content in Skeena and Regina cherry cultivars grown under the ecological conditions of Mihalıççık, Eskişehir, and to determine the appropriate dose of nutrient regulators. The study was carried out on 8-year-old Regina and 12-year-old Skeena cherry trees. Chitosan and melatonin preparations were applied to the leaves at four different concentrations (0, 50, 100, and 150 ppm) using a backpack sprayer. According to the findings, in the Skeena cultivar, nitrogen (N) content was 1.92% in the control, 1.98% at 100 ppm, and 1.88% at 150 ppm, showing no consistent increase with higher doses. Phosphorus (P) content showed no significant changes, while potassium (K) reached 22.310 mg/kg at 150 ppm. Calcium (Ca) levels remained below the control, magnesium (Mg) showed no significant differences, and Fe and Cu decreased at higher concentrations. Zn remained below control, and Mn decreased with increasing doses. In melatonin applications, significant increases were observed in N, P, K, Ca, Mg, and Fe, while Cu, Zn, and Mn contents were below control levels. Results indicate that melatonin may serve as a biofertilizer alternative by increasing nutrient content in cherry leaves. However, further studies at different times and orchards are recommended for elements such as Cu, Zn, and Mn.