Five tomato cultivars were tested for tolerance to chilling. After exposure of varying times to chilling at 3 °C, the fruits were returned to ambient temperature for development of chilling injury (CI) symptoms (uneven ripening and pitting). Ripening was assessed by measuring carotenoids. Electrical conductivity (EC) of leachate from pericarp discs, an indirect measure of membrane damage, was used to determine CI. During chilling EC greatly increased in the three sensitive cultivars, but hardly in the tolerant ones, in good correlation with the development of CI symptoms after rewarming. However, this correlation broke down after returning the fruit to 20 °C. While slightly injured fruit showed a large increase in EC, surprisingly EC was drastically reduced in the extensively injured fruit. Calcium pectate production due to cell wall degradation may explain the lack of correlation between EC and CI after rewarming. We conclude that EC is not always a reliable measure of membrane damage.
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