BITTER PIT AND VASCULAR FUNCTION IN APPLES

The xylem vasculature in the fruit of apple suffers a progressive dysfunction during the season. The progress of xylem dysfunction was recorded in ten commercial apple cultivars. Dysfunction was found to be more severe in some cultivars than in others. A significant relationship was found between the susceptibility of a cultivar to bitter pit and the rate at which its xylem became dysfunctional. Dysfunction generally occurred earlier in the more susceptible cultivars. This observation fits with the idea that calcium (Ca) inflow will cease earlier in bitter pit-susceptible cultivars and so could explain their heightened susceptibility.