Twenty-five commercially available turfgrass cultivars were evaluated for cumulative evapotranspiration (ETcum) attributes under progressive water stress for 0 to 21 and 0 to 24 days using the gravimetric mass balance method in two greenhouse studies. At the end of the water-stress treatment, the cultivars were scored visually for their green appearance on a 0 (no green) to 10 (100% green) scale. The Gompertz nonlinear model gave a best fit to ETcum vs. days adjusted for pan evaporation variation in the greenhouse compared with monomolecular and logistic nonlinear regression models. Two ETcum attributes—maximum evapotranspiration rates (ETmax) and inflection time (ti) (the time when the change in ET becomes zero)—were estimated for each cultivar using the Gompertz model. Based on final ETcum, ETmax, ti, and greenness score, `Bristol', `Challenger', and `Wabash' Kentucky bluegrass (Poa pratensis L.); `Shademaster' creeping fescue (Festuca rubra L.); `FRT-30149' fine fescue (F. rubra L.); and `Aurora' hard fescue (F. ovina var. duriuscula L. Koch.) were identified as low water-use cultivars.
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