The cold resistance of two winter wheat cultivars appraised by the freezing method in a experiment room

Imitating the regularity of temperature variation in the winter wheat field of Chifeng City，in Inner-mongolia and the northeast regions by using the freezing method．two hardier cuhivars “Norstar’’and “Mironovskaia 808’’are selected tO determine their 1etha1 temperatures．The LT20 of “Norstar” and “Mironovskaja 808”is -26．2℃ and -23．9℃ ．the LT50 is-27．712 and -26．3℃ respectively in January；the freezing tolerance of the varieties in February is 1ass-hardened。their LT20 is -10．0℃ and -8．912 and the LT50 is -12．912 and -11．7℃ respectively．