Dehardening and Rehardening of Spring-Collected Winter Wheats and a Winter Rye

Crowns of winter wheat (Triticum aestivum L.) and rye (Secale cereale L.) collected early in the spring readily dehardened upon exposure to 15 C. After 6 days at 15 C, the crowns of both species were completely dehardened. Partially dehardened crowns were unable to reharden upon exposure to cold-acclimating conditions and continued to lose hardiness when stored at − 2.5 C. There was a positive correlation between level of dehardening and crown moisture content. However, this relationship began to break down when attempts were made to reharden partially dehardened plants.