Wheat and Barley Vernalization in a Precise Temperature Gradient¹

Rate of meristem elongation of the primary culm in winter wheat ( Triticum aestivum L.) and barley ( Hordeum vulgare L.) was a function of temperature and length of cold treatment. Elongation of the wheat meristems did not begin unless the seedlings had a minimum of 15 days at 5 to 8 C. Effectiveness of the cold treatment in wheat seedlings was maximum at 7 C but decreased very rapidly if the vernalization temperature was raised to 9 C or lowered to 3 C. The barley variety required a vernalization period greater than 12 days. Effectiveness of the cold treatment of barley seedlings was maximum at 9 C and decreased rapidly if the vernalization temperature was raised to 12 C or lowered to4 C.