Tall fescue germplasm response to freezing temperatures

Tall fescue [Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.] is a perennial cool‐season grass in which improved freeze tolerance could result in greater winterhardiness and persistence. Our objective was to evaluate survival and freeze‐tolerance thresholds of ‘Flecha’ summer‐dormant (SD) and ‘Texoma Max QII’ summer‐active (SA) tall fescue at seedling (1–2 leaves) and tillered (5–6 leaves) growth stages using controlled environment freezing chambers. Target temperatures ranged from 0 to −9 °C (seedlings) and 0 to −12 °C (tillered plants). Predicted lethal temperature at which 50% mortality occurs (LT50) was −5.7 and −5.5 °C for SA and SD seedlings, respectively, and −6.0 and −5.7 °C for SA and SD tillered plants, respectively. Based on these results, a controlled temperature chamber appears to be a useful tool for plant breeders when evaluating survival and freeze tolerance of SA and SD tall fescue germplasm at seedling and tillered growth stages.