FREEZING TOLERANCE AND CARBOHYDRATE CONTENT OF LOW-TEMPERATURE-ACCLIMATED AND NONACCLIMATED CENTIPEDEGRASS

Little is known about environmental and physiological factors affectin g centipedegrass [Eremochloa ophiruoides (Munro) Hackel] winter surviv al. Stolons of common and 'Oklawn' centipedegrass were sampled from fi eld- or growth chamber-grown turf in three separate experiments to (i) determine freezing tolerance of acclimated and nonacclimated turf; (i i) identify and quantify nonstructural carbohydrates (NSC) in acclimat ed and nonacclimated turf, and (iii) relate NSC levels to freezing tol erance. Lethal temperatures for common and Oklawn were similar through out all studies. Freezing tolerance estimated by electrolyte leakage f or turf sampled from the field in winter 1988-989, indicated that leth al temperatures ranged from about - 7 to - 8-degrees-C in February and March, to - 9-degrees-C in December and January. In a 1990-1991 field and growth chamber studies, injury was estimated by stolon recovery g rowth in the greenhouse after freezing at - 2, - 4, - 6, - 8, and - 10 -degrees-C for 1 h. Lethal temperatures in mid-winter were almost-equa l-to 2-degress-C lower than in fall or spring during active growth. In stolons, starch and sucrose were the primary NSC ranging from almost- equal-to 2 to 13 mg (100 mg)-1 dry weight. Sucrose was higher in accli mated than pre- or post-acclimated turf. In a growth chamber study, 47 % more sucrose was present in acclimated vs. preacclimated turf. Sixty -nine percent more acclimated stolons survived - 4-degrees-C than prea cclimated stolons, and a positive correlation (r = 0.78) was observed between sucrose level and number of surviving stolons. Higher sucrose concentrations in low-temperature-acclimated vs. nonacclimated common centipedegrass stolons may be a component of improved freezing toleran ce.