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Evapotranspiration, Rooting Characteristics, and Drought Response: A Comparison Between Hybrid Bluegrass and Kentucky Bluegrass
ABSTRACT Kentucky bluegrass (Poa pratensis L.) (KBG) is the predominant cool-season turfgrass used throughout temperate regions and the transition zone of the USA. In the arid and semi-arid west, some government agencies have imposed restrictions on its use due to its sensitivity to drought. Hybrid bluegrass (HBG), a cross between native Texas bluegrass (Poa arachnifera Torr.) and KBG, has been released as a heat resistant bluegrass for the southern USA where KBG is unable to withstand high summer temperatures. It is unknown if HBG possesses the ability to avoid drought, unlike KBG. Hence, our objectives were to compare water use rate and drought avoidance of KBG and HBG. Studies were conducted in both the field and greenhouse during 2000 and 2001 at Fort Collins, CO to examine ET rates under non-limiting soil moisture conditions, vertical rooting patterns, and relationships among surface soil water depletion (SWD), shoot water content (SWC), and turfgrass response to drought. In the field, mean HBG ET (5.0 mm d-1) was significantly less than that of KBG (6.1 mm d-1) during the period of July through Sep during 2000 and 2001. As evaporative demand increased, the magnitude of difference in ET rate between HBG and KBG increased. Mean HBG clipping yield in the |
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