Etiology and Postharvest Control of Finger Drop Disorder in ‘Cuarenta Dias’ Banana (Musa acuminata AA Group)

Finger drop is a postharvest physiological disorder of banana wherein ripe fruits readily fall off from the crown. The incidence of this disorder limits the marketability of ‘Cuarenta Dias’ banana, an important commercial cultivar grown in the Philippines. This study aimed to describe the etiology of finger drop and its postharvest control using generally regarded as safe (GRAS) chemicals. Results showed that finger drop disorder of ‘Cuarenta Dias’ banana was associated with localized weakening of the peel at the pedicel-end portion of the fruit during ripening. The onset of finger drop occurred at peel color index 4 (PCI 4, more yellow than green) coincident with the respiratory climacteric peak that was preceded by peak ethylene production. Associated with the onset of finger drop at this ripening stage were significant reduction in peel thickness and breaking load at the pedicel-end, and concomitant loss of moisture, starch conversion, reduction in calcium content, and increase in activity of polygalacturonase. Application at the pedicel-end portion with 200 ppm gibberellic acid (GA), 4% calcium chloride (CaCl2), or 60% v/v ethanol (EtOH) were effective postharvest treatments against the disorder, with no finger drop occurrence 15 d at ambient storage. Control of finger drop by any of these chemical treatments was associated with delayed peel color development and ripening events. Key Words: banana, ‘Cuarenta Dias’, finger drop, Musa acuminata AA Group, postharvest chemical treatments, ripening Abbreviations: CaCl2 – calcium chloride, EtOH – ethanol, GA – gibberellic acid, PCI – peel color index, PG – polygalacturonase, VQR – visual quality rating