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

Little is known about environmental and physiological factors affecting centipedegrass [Eremochloa ophiruoides (Munro) Hackel] winter survival. Stolons of common and 'Oklawn' centipedegrass were sampled from field- or growth chamber-grown turf in three separate experiments to (i) determine freezing tolerance of acclimated and nonacclimated turf; (ii) identify and quantify nonstructural carbohydrates (NSC) in acclimated and nonacclimated turf, and (iii) relate NSC levels to freezing tolerance. Lethal temperatures for common and Oklawn were similar throughout all studies. Freezing tolerance estimated by electrolyte leakage for turf sampled from the field in winter 1988-989, indicated that lethal 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 growth in the greenhouse after freezing at - 2, - 4, - 6, - 8, and - 10-degrees-C for 1 h. Lethal temperatures in mid-winter were almost-equal-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 acclimated 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 preacclimated 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 tolerance.