RELATIVE HARDINESS OF STRAWBERRY CULTIVARS AT THREE TIMES OF THE WINTER

Abstract

The electrical conductivity and recovery methods were used to assess the hardiness of four strawberry genotypes in late October, mid-January, and early March. The temperatures at which the plants were stored decreased from above 0 C in October to −8 C in mid-January, and then increased to −3 C in March. A stress temperature of −9 C was sufficient to determine differences in hardiness in October but a sequence of temperatures of −9, −10.5, and −12 C were required in January and March. All genotypes increased in hardiness between October and March, but were beginning to lose hardiness in March at −12 C. The relative hardiness of the genotypes did not change as winter progressed and both the recovery and conductivity methods could be used to determine relative hardiness at all times, provided sufficient cold stress was applied. The electrical conductivity method is preferred because it does not take as long to complete, is not affected by differences in dormancy, and the significance of differences can be determined more readily.