Differences in the surface structures of three mango cultivars and the effect of kaolin on these structures.
Plooy W. du, Merwe C. van der, Korsten L.
Author Affiliation: Department of Microbiology & Plant Pathology, University of Pretoria, Pretoria 0002, South Africa.
Research Journal - South African Mango Growers' Association 24 : 29-36
Abstract : The microscopic rind structures of three mango cultivars, namely Tommy Atkins, Kent and Keitt, were compared. Lenticel morphology, wax layers and cuticle thickness were investigated in mango fruits collected from Bavaria estates (Mpumalanga Province, South Africa) throughout the 2002/03 and 2003/04 seasons from anthesis to harvest. No significant differences in the wax layers or cuticle thickness outside the lenticels could be identified, but the morphology of the lenticels is different for individual cultivars. Phenolics present in the lenticels are not cultivar-specific and point towards the evolutionary development of a self-defence mechanism by the species rather than horticultural cultivar development. The quantities of wax, suberin and cutin present in the lenticels, however, are cultivar dependent, which could contribute to the sensitivity of the lenticels. Mango fruit wax is complex and consists of chemically identifiable fractions that vary in composition in different surface areas. The wax layer determines the surface tension of the fruit rind, which is a very important parameter in the application of commercial wax. It was found that the surface tension was disrupted by the presence of kaolin, applied as part of preharvest disease control measures, consequently leading to an unsatisfactory wax film.