Exogenous melatonin and interstock treatments confer chilling tolerance in citrus fruit during cold storage

Fruit quality can be improved using rootstocks and melatonin (MT) after harvest. However, the effects of the combined use of interstocks and MT on citrus fruit storage quality and physiological senescence are unknown. Hence, this study aimed to assess how MT treatment affects the organoleptic quality and antioxidant system of Kiyomi Tangor fruit obtained from trees growing on rootstocks with and without interstocks during the cold storage period. All treatments reduced fruit weight loss while increasing firmness, soluble sugars, total soluble solids, titratable acids, and skin color as compared with those of the control, indicating that MT and rootstocks slowed the deterioration of fruit quality during cold storage. Furthermore, the combined use of interstocks and MT prevented electrolyte leakage and malondialdehyde from accumulating, suggesting the potential hindrance of reactive oxygen species (ROS) generation and oxidative harm. This can be attributed to the improved efficacy of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase in removing ROS. Although both MT and rootstocks can improve the quality of Kiyomi Tangor fruit after harvest, the combination of MT and interstocks provided the highest quality during cold storage.