Correlation of bitter pit on northern soy apples with bitter pit-like symptoms induced by Mg2+ salt infiltration

Abstract

Abstract Induction of bitter pit-like symptoms (Mg2+ induced pits [MgIP]) on Northern Spy apples (Malus domestica borkh.) by infiltrating Mg2+ salt solutions into the fruits was positively correlated with bitter pit that developed naturally during storage. Fruits at harvest were infiltrated with 0.1 M MgCl2 in 0.3 M sorbitol with 0.1% Tween 20 and placed at 20°C for 10 days (d) after which the number of MgIP was determined on individual fruits. A parallel sample of fruits from each orchard was stored at 5°C in air (both years) and at 3°C in air or controlled atmosphere (CA) storage in the second year. MgIP was positively correlated with bitter pit development in storage for fruits harvested 20 d and 10 d before and at optimal maturity for long-term storage. The endogenous (native) fruit Ca2+ concentration was inversely related to the number of pits induced by Mg2+ and to bitter pit development following storage.