Crop Load Affects Mineral Concentrations and Incidence of Bitter Pit in `Cox's Orange Pippin' Apple Fruit

in Journal of the American Society for Horticultural Science
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  • 1 Department of Scientific and Industrial Research Fruit & Trees, Mt. Albert Research Centre. Private Bag, Auckland, New Zealand

Apple fruit (Malus domestics Borkh. cv. Cox's Orange Pippin) were harvested in four orchards from trees growing under the same conditions but differing in crop load. Regardless of fruit size, apples from light-cropping trees had lower Ca and higher K concentrations and more bitter pit than did fruit from trees with heavy crop loads. The inverse relationship between Ca concentration in the fruit and the incidence of bitter pit also varied according to crop load and could affect the ability to predict incidence of bitter pit from Ca measurements. Differences in fruit maturity that would influence bitter pit incidence were not associated with crop load. The enhanced susceptibility to storage disorders, such as bitter pit, in fruit of all sizes from light-cropping trees suggests the need to handle fruit from such trees differently for postharvest storage.