LABORATORY FREEZE TOLERANCE OF FIELD-GROWN FORAGE BERMUDAGRASS CULTIVARS

Freeze tolerance is a limiting factor in production of many bermudagra sses (Cynodon spp.) in the transition zone between warm- and cool-seas on grasses. Our objective was to evaluate the seasonal patterns of fre eze tolerance in five forage bermudagrass cultivars. Midland, Hardie, Tifton 34, World Feeder, and Gordon's Gift were grown in field plots a nd acclimated under natural conditions, then subjected to laboratory f reeze tolerance evaluations. Lowest survival temperatures (LSTs) were determined at monthly intervals from November through May in 1992-1993 and 1993-1993, LSTs were between -5 and -7 degrees C for all cultivar s in early November. Gordon's Gift had the greatest freeze tolerance i n midwinter, surviving exposure to approximate to -11 degrees C in 199 2-93 and approximate to -10 degrees C in 1993-94. Gordon's Gift was si gnificantly more freeze tolerant than the other cultivars on most date s. The differences in freeze tolerance among the cultivars tested indi cates substantial variation in the species that may be used for breedi ng improvement.