Evaluation of cold tolerance in some alfalfa (Medicago sativa L.) ecotypes under field condition

Survival and profitability of alfalfa fields in cold regions is affected by winter injury and parts of alfalfa fields are subject to damage or destruction due to winter conditions every year. In this study eleven alfalfa ecotypes with two international cultivars were evaluated as check in ''Tikmadash station''، Tabriz، Iran with an ultra-cold climate from 2008 to 2011. Seeds were first planted individually in pots and seedlings were transplanted to the field based on a randomized complete block design with five replications. Various traits were measured for 3 years in the field. After each snowfall، the farm was completely shoveled for to remove the protective influence of snow and plants were exposed to the cold of winter. First year was considered as the estblishment year and data recording was taken place from the second year. ANOVA results for the survival percentage showed that there were significant differences in plants survival percentages amongst ecotypes and cultivars in the second and third years compared to the first year، but this trait was not significantly different between second and third years. This indicates that the most damages and plants death accrued at the first year. Ranger and Moapa cultivars showed the most winter damage and the most winter survival was belong to Joshin ecotype. To gain a better conclusion، the mean of adjusted yields of ecotypes and cultivars for three years were calculated and based on obtained results ‘Bahraman’، ‘Joshin’، ‘Horand’، ‘Dizaj-Safarali’ and ‘Alhord’ ecotypes were determined as the best ecotypes of this study.