Physico-chemical Responses of Mango (Mangifera indica L. cv. Carabao) Fruit to Melatonin Under Chilling Stress

Abstract

‘Carabao’ mango fruit is highly susceptible to chilling injury (CI) when stored at sub-optimal temperature for extended period. Melatonin (MLT) was reported to ameliorate chilling injury (CI), hence this study aimed to enhance the cold tolerance of ‘Carabao’ mango fruits through MLT treatment. Mature green mango fruits were dipped for 10 min in varying concentrations (0.1, 0.5 and 1.0 mM) of MLT then stored at 7^oC for six weeks followed by poststorage at 24^oC. Dramatic amelioration of CI with MLT was achieved during the 3-week storage at 7^oC. Melatonin at 1.0 mM delayed the onset of CI and reduced the incidence of external CI symptoms like lenticel spotting and peel discoloration as well as internal CI symptoms manifested as vascular streaking, pulp cavitation, and flesh browning. MLT however, did not significantly retard the rate of ripening of mangoes during storage at 7^oC. The high visual quality rating was maintained for three weeks at 7^oC in both treated and control fruit. MLT only delayed the onset of disease but did not significantly reduce disease incidence. Upon withdrawal from cold storage and at the ripe stage, mangoes treated with MLT had lower total soluble solids content than the control. On the other hand, titratable acidity upon withdrawal from cold storage and at the ripe stage was not affected by MLT treatment.