The aim of this study was to identify the most suitable concentration of melatonin (MT) for peach growth and nutrient uptake. The effects of exogenous MT on the growth and nutrient absorption of peach (Prunusdavidiana) seedlings were investigated in a pot experiment. Compared with the control, treatments with MT at 50–200 µM increased the organ biomasses and chlorophyll contents of peach seedlings, with the highest values in the 150 µM MT treatment. The MT treatments also enhanced the resistance of peach seedlings by regulating the activities of antioxidant enzymes (superoxide dismutase and catalase), decreasing lipid peroxidation (as determined by malondialdehyde content), and altering the contents of osmotic adjustment substances (soluble protein and proline). Treatments with MT increased the contents of macronutrients (nitrogen, phosphorus, and potassium) in the shoots of peach seedlings, with the 150 µM MT treatment being the most effective. The contents of trace elements (calcium, magnesium, sodium, and boron) in peach seedlings were also increased to varying degrees by MT treatments. Therefore, exogenous MT can promote the growth and nutrient absorption of peach seedlings, and 150 µM is the optimal MT concentration. [ABSTRACT FROM AUTHOR]