Characteristics of the surface of banana peel in cultivars susceptible and resistant to maturity bronzing

Abstract

Maturity bronzing, a disorder of banana fruit in the humid tropics, is characterised by a preharvest discoloration of the peel. Lesions in the peel of the commercial banana cultivar Williams occur on the surface of the fruit peel primarily in the wet season and their formation involves (i) separation of epidermal cells and (ii) intercellular cracking. During rapid growth the epidermis and the cuticle appear to be insufficiently elastic to accommodate the expansion of internal tissues. The resulting fracture patterns indicate that maturity bronzing is stress induced. Development of the epidermis of the fruit peel was studied by scanning electron microscopy in susceptible and resistant banana cultivars. Observations were compared with those found for the commercial cultivar Williams. At bunch emergence, susceptible cultivars had ridged epidermal cells but the epidermal cells of resistant cultivars had papillate outgrowths.