<span style="font-size:14.0pt;mso-bidi-font-weight:bold">Studies on the relationship between fruit calcium content and lipoxygenase activity with bitter pit incidence in 'Royal Delicious' apple (<i>Malus domestica </i>Borkh.) during storage </span>

Abstract

During storage, apple fruit suffer from bitter pit (BP), a serious physiological disorder. If fruit Ca content during storage is low lipoxygenase (LOX) activity is also likely to be high and vice versa, which may influence the occurrence of bitter pit. The incidence of bitter pit, fruit Ca contents, rates of ethylene evolution and respiration, and LOX activity in 'Royal Delicious' apples were studied up to 6 month of storage at 2±1ºC and 90-95% RH. BP appeared after 3rd month of storage, which increased up to 22.2% in the 6th month of storage. Fruit Ca contents showed declining trend with storage. Ca contents were significantly higher in healthy fruit than bitter-pitted fruit, and decreased with storage period. Conversely, LOX activity was lower in healthy fruit than bitter-pitted fruit, which increased with storage time. The rates of ethylene evolution and respiration were significantly lower in healthy fruit than bitter-pitted fruit. The correlations (R²) between Ca content and bitter pit (R² = -0.77), and between Ca content and LOX activity were strongly negative (R² = - 0.94); but between LOX activity and bitter pit was strongly positive (R² =+ 0.87), indicating inverse relationship between fruit Ca content and bitter pit, and between fruit Ca content and LOX activity.