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Title: The relationship of LT50 to prolonged freezing survival in winter wheat

Author
item Skinner, Daniel
item Garland-Campbell, Kimberly

Submitted to: Canadian Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2008
Publication Date: 9/1/2008
Citation: Skinner, D.Z., Garland Campbell, K.A. 2008. The relationship of LT50 to prolonged freezing survival in winter wheat. Can. J. Plant Sci. 88: 885-889.

Interpretive Summary: The ability to survive the winter in a frozen state is essential to productive winter wheat plants. The LT50s can be determined for wheat cultivars and are the temperatures at which 50% of the plants are expected to die because of freezing injury. The relationship of the LT50 to the ability to survive being frozen for 15 or 20 weeks was examined in 25 wheat cultivars. The LT50 was strongly related to the ability to survive being frozen for as long as 20 weeks. This result indicated that the LT50, which can be determined in about eight weeks, can be used confidently to predict long-term freezing survival in winter wheat.

Technical Abstract: Twenty-five wheat (Triticum aestivum L.) cultivars were tested for their ability to withstand remaining frozen for extended periods of time. Survival of fully acclimated seedlings was evaluated after remaining frozen at -5°C for 15 or 20 wks. Survival after 15 wks ranged from 0 to 100% and after 20 wks ranged from 0 to 33%. The rankings of the cultivars based on survival after 15 wks was highly correlated with the rankings after 20 wks, indicating a consistent decline in survival over the 20 wk period. The relationship of survival and LT50 scores (lethal temperature 50%), the temperatures at which 50% of the plants were predicted to die, was examined with linear regression analysis. The linear relationship was highly statistically significant after both time periods. The cultivars Norstar and Froid survived being frozen for 20 wks nearly twice as well as the other cultivars; about 33% vs. 17% for the next best cultivar. These results indicated that the LT50 score, which can be estimated in about 8 wks, typically accurately predicts the ability to survive in the frozen state for as long as 20 wks, and that Norstar and Froid possess a long-term freezing tolerance mechanism that is far superior to the other cultivars tested.