Tuesday, 8 November 2005
33

Controlled Freezing of Turf-Type Tall Fescue Cultivars.

Eric Watkins, Andrew B. Hollman, and Brian P. Horgan. University of Minnesota, 305 Alderman Hall, 1970 Folwell Ave, St. Paul, MN 55108

Tall fescue is not used extensively as a turfgrass in the most northern regions of the United States due to inconsistent winter performance. Improved turf-type tall fescue cultivars could have several benefits to turfgrass managers in Minnesota and other areas of the northern U.S.; these include excellent wear tolerance and very good drought avoidance characteristics. Poor winter survival could be caused by several factors including crown hydration, disease, desiccation, extended periods of ice cover, and death caused by low temperatures. In order for new cultivars of winterhardy turf-type tall fescue to be developed, current tall fescue germplasm needs to be evaluated for responses to various components of winter stress. Additionally, an effective laboratory screening method could be an effective tool for plant breeders. A controlled freezing study consisting of two experiments was conducted on 20 tall fescue cultivars representing a diverse sample of turf-type tall fescue germplasm. In the first experiment, ten-week old seedlings were placed either under typical greenhouse conditions or under acclimating conditions (8 h day, 4oC) for 4 wk. Freezing stress was then initiated on acclimated plant for 24 h. at the following temperatures, depending on treatment: 0oC, -5oC, -10oC, -15oC, -20oC. Non-acclimated plants were stressed at either -5oC or -10oC. Plants were then allowed to thaw at 4oC for 24 h and returned to the greenhouse. All acclimated plants died at -10oC, -15oC, and -20oC. All non-acclimated plants died at -10oC. Acclimated plants experienced limited survival at -10oC. In the second experiment, plants were 12 weeks old prior to acclimation; this experiment yielded similar results to the first experiment. Correlations with field performance will be discussed.

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