Survival of Turfgrasses Under Extended Ice Cover in a Controlled Environment.

In Northern climates, roadside grasses can experience ice cover from snow being plowed off of roads, refreeze of melt water from deicers used to keep roads accessible, and variability in winter weather. Tolerance to ice cover varies with species, cultivar and duration of ice cover. In order to better select turfgrasses for use on roadsides in cold climates, more information is needed about species and cultivar differences for tolerance to extended ice cover. Additionally, turfgrass breeders would benefit from improved selection methodologies. Therefore, we aimed to screen turfgrasses that could be used in roadside mixtures for ice cover tolerance in a controlled environment. Thirty five turfgrass cultivars and selections, representing 14 species, were subjected to controlled ice encapsulation. All turfgrasses were sown at 2 pure live seeds/cm2 into 3.75 cm diameter cone-tainers. They were grown for 10 weeks under greenhouse conditions with a 16-hour photoperiod and acclimated for 2 weeks at 2°C with an 8-hour photoperiod before being frozen at -2°C. Aluminum sleeves were added to the tops of the cone-tainers and then ice cubes and water were slowly added to to create a uniform ice depth of 5.1 cm above the soil surface. Ice cover was maintained for either 4, 8 12, or 16 weeks by water application twice each week. After treatment, plants were thawed for 48 hours at 2°C and then returned to the greenhouse for recovery. Plants were rated for survival 4 weeks after thaw and digital images were taken at 31 days to assess recovery. Differences were seen between species and also between cultivars or selections within a species. Results contradicted our observations in field trials, suggesting there is a need to refine our methods in order to better identify grasses that can tolerate extended periods of ice cover under field conditions.