Objective This study aimed to investigate the physiological mechanism by which exogenous melatonin (MT) regulates cell wall metabolism to delay the softening of stripped apricots during cold storage.

Methods In this experiment, stripped apricot fruits were treated with MT at different concentrations (0, 50, 100, 200, and 400 μmol/L) and stored at (0 ± 0.5) °C for 49 days. Changes in fruit quality, cell wall components and cell-wall-degrading enzyme activities were systematically assessed, and cell wall ultrastructure was observed using transmission electron microscopy.

Results MT treatment effectively inhibited the ethylene release rate and respiration intensity of stripped apricot, and delayed the decrease in firmness. Among them, 200 μmol/L MT treatment exhibited the best effect: significantly inhibited the activities of cellulase, β-glucosidase, and β-galactosidase, slowed down the reduction in the contents of protopectin, cellulose, and hemicellulose as well as the increase in the content of soluble pectin, thereby better maintained the integrity of cell wall structure and ultimately delayed fruit softening.

Conclusion Exogenous melatonin can delay the softening process of stripped apricots during cold storage by regulating the cell wall metabolic pathway, and 200 μmol/L is recommended as the optimal concentration.