The relationship of LT₅₀ to prolonged freezing survival in winter wheat

Abstract

Twenty-six wheat (Triticum aestivum L.) lines were tested for their ability to withstand remaining frozen for extended periods of time. Survival of acclimated seedlings was evaluated after remaining frozen at -5°C for 15 or 20 wk. Survival after 15 wk ranged from 0 to 100% and after 20 wk ranged from 0 to 33%. The relationship of survival and LT 50 scores, 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 15 wk and after 20 wk. The cultivars Norstar and Froid survived being frozen for 20 wk 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 wk, reliably predicts the ability to survive in the frozen state for as long as 20 wk, and that Norstar and Froid possess a long-term freezing tolerance mechanism that is far superior to the other cultivars tested. Key words: Winter wheat, freezing tolerance, freezing injury