Reddening disorder of 'Honey Gold' mango fruit, preharvest bagging and postharvest lighting

Abstract

The mango cultivar 'Honey Gold' (HG) was developed in Queensland, Australia. Ripe defect-free HG fruit are characterized by bright yellow skin with red blush on their sun-exposed shoulders. HG mangoes are mostly grown from the Northern Territory down though Queensland into northern New South Wales (nNSW). As with many mango cultivars, HG suffers from a range of skin disorders. However, HG mango fruit grown in nNSW almost uniquely express a blotchy 'skin reddening' disorder that detracts from their visual appeal. The non-uniform reddening, which can encompass 'red lenticels', appears to be a host defense response. Causal agents of the reddening disorder are currently elusive. There may be a range of pre- and postharvest abiotic and/or biotic stresses, and they could be additive. A number of physical and chemical treatments were applied pre- or postharvest with a view to either suppress (i.e., prevent) or enhance (i.e., mask) uneven skin reddening. The physical treatments included preharvest fruit bagging and post-harvest exposure to different wavelengths of light. These physical treatments are considered in this paper. The chemical treatments included known modulators of host defense and ethylene responses. Those treatments are not reported in this short paper. However, among the full suite of treatments tested, one only notably influenced skin reddening. In this case, postharvest exposure to blue light increased reddening. Future research with HG will build on this initially promising finding.