Freezing Resistance and Carbohydrate Composition of `Floratam' St. Augustinegrass

Abstract

`Floratam' St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] stolons were sampled from the field between October and March to determine potential changes in lethal low temperatures and nonstructural carbohydrate composition. Lethal temperatures determined by electrolyte leakage ranged from – 6.1 to – 5.3C. Little variability in lethal temperatures over sampling dates indicated that `Floratam' St. Augustinegrass did not readily acclimate to cold temperatures. Starch was the carbohydrate present in highest concentration in `Floratam' stolons, with levels ranging from 7.7 to 12.4 mg/100 mg dry weight. Sucrose concentrations varied from 2.4 to 5.7 mg/100 mg dry weight. Glucose and fructose were also present in `Floratam' stolons at lower concentrations. A slight increase in sucrose and decrease in starch were observed between November and December, when low temperatures resulted in chlorophyll loss and turf was <25% green. On all other sampling dates, changes in sucrose and starch were variable. Changes in concentration of total nonstructural carbohydrates or soluble sugars did not seem to influence the freezing resistance of `Floratam' St. Augustinegrass.