Evaluation of freezing injury in temperate fruit trees

Abstract

Freezing is a major environmental stress limiting the geographical distribution, growth, and productivity of temperate fruit trees. The extent of freezing injury in the trees depends on the rate at which the temperature decreases, the minimum temperature reached, and the duration of the freezing conditions. The ability to tolerate freezing temperatures under natural conditions varies greatly among fruit tree species, cultivars, and tissues. Freezing injury must be precisely evaluated to reliably predict the winter survival and productivity of the trees in specific regions, to screen for tolerant species and cultivars, and to develop cultural strategies that reduce freezing stress. Various methods are used to evaluate freezing injury in temperate fruit trees under field and artificial conditions, including visual evaluation of tissue discoloration, thermal analysis, determination of electrolyte leakage, and triphenyl tetrazolium chloride reduction analysis. In this review, we describe the most frequently used experimental procedures for evaluating freezing injury.