Cool‐Season Turfgrass Responses to Drought Stress1

Abstract

As the supply of water available for turf irrigation becomes limited, it is important to identify water‐efficient and drought‐tolerant turfgrasses. To establish the critical soil water potential at which cool‐season turfgrasses begin to experience drought stress, the growth and quality responses of Poa pratensis L. ‘Baron’, Lolium perenne L. ‘Yorktown II’, Festuca rubra var. commutata Gaud. ‘Jamestown’ and Festuca ovina var. duriuscula (L.) Koch ‘Tournament’ drought stress were compared in a greenhouse study. Evapotranspiration (ET) rates were measured using weighing lysimeters containing undisturbed cores of mature turf growing in a silt loams oil. Tensiometers and electrical resistance blocks were installed in a separate set of eight lysimeters containing L. perenne to determine the relationship between water loss due to ET and soil water potential. The ET rates of all grasses were unaffected until the soil water potential reached −50 to −80 kPa. During further soil water depletion, ET rates declined and drought stress symptoms became apparent. Leaf water potential of P. pratensis and L. perenne decreased by 50 to 75% when soil water potential declined to −80 kPa, while that of Festuca species remained relatively constant to a soil water potential of −400 kPa. Based on the parameters measured, P. pratensis and L. perenne exhibited a more rapid decline in ET rate, quality, and leaf growth under moisture stress than the two Festuca species, which demonstrated greater ability to thrive with limited soil moisture.