Abstract
Changes in hardiness and plant constituents associated with hardening were observed in ‘Pawnee’ winter wheat under constant and under decreasing photoperiod and temperature treatments. Hardening occurred only when the temperature decreased, and was greater under a constant long photoperiod than under a decreasing photoperiod. Least hardening occurred when the photoperiod was decreased and the temperature remained constantly high.Changes in dry matter, reducing sugar, sucrose, and free amino acid contents of wheat crowns paralleled changes in hardiness. Soluble protein content of crowns was increased by decreasing photoperiod as well as by decreasing temperature.