EVALUATION OF AN ELECTROLYTE LEAKAGE TECHNIQUE TO PREDICT ST-AUGUSTINEGRASS FREEZING TOLERANCE

Stolons of 'Raleigh', 'Floratam', and FX-332 St. Augustinegrass [Steno taphrum secundatum (Walt.) Kuntze] were sampled from the field between October and March in two consecutive years to evaluate accuracy of an electrolyte leakage (EL) method for predicting freezing tolerance. Le thal temperatures of stolons estimated using EL were compared to those obtained by regrowth tests in the greenhouse. Mean lethal low tempera tures for regrowth and EL methods over 12 sampling dates were 'Florata m', -4.5C (regrowth) vs. -4.4C (EL); FX-332,-4.2C (regrowth) vs. -4.9C (EL); and 'Raleigh', -6.0C (regrowth) vs. -5.4C (EL). A positive corr elation (r = 0.81) was observed between EL-predicted and regrowth leth al temperatures for 'Raleigh', which exhibited some acclimation during the first sampling year. The EL technique consistently predicted a lo wer lethal temperature for 'Raleigh' than for 'Floratam', which corrob orates field observations concerning freezing tolerance of these two c ultivars.