Factors associated with 'maturity bronzing' of banana fruit

Abstract

Maturity bronzing', a severe skin blemishing of banana fruits of unknown cause, is of considerable economic importance in north Queensland. Two treatments were imposed on a set of 68 plants; these were bunch covering (aimed at influencing bunch microclimate) and removal of hands and leaves (aimed at influencing rate of filling). A series of observations was recorded from emergence to harvest; these were blemish details (13 attributes), morphological characters (15 attributes) and meteorological data (34 attributes). Numerical methods were used to relate severity of blemish to the other attributes. Imposed treatments were completely without effect. Morphological comparisons showed that severe bronzing was commoner in rapidly-filling fruit from plants with a reduced pseudostem girth and a small number of hands. The most striking associations were with meteorological conditions; severe blemishing is highly significantly associated with hot, humid, overcast conditions. The evidence is consistent with the hypothesis that bronzing is due to excessive turgor pressure, resulting from rapid water uptake when transpiration is low.