Seasonal Drought Stress Response of Kentucky Bluegrass (Poa pratensis L.) in the Intermountain West.

In the Intermountain West region, significant amounts of water is used for the irrigation of turfgrass. There is little specific research in drought stress of turf especially during the different seasons and in association with climate parameters. A better understanding of these relationships will improve irrigation efficiency. Our objectives were to determine actual ET for Poa pratensis throughout the growing season; determine changes in actual ET of Poa pratensis as it enters drought stress and relate to climatic conditions; and describe the physiological responses of Poa pratensis to drought stress and climatic conditions and relate to visual appearance. We conducted an observation experiment on a large field of Kentucky bluegrass (Poa pratensis). This entire area was subjected to dry-down events once each month. During that time we measured several plant physiology characteristics in 12 subplots within the field. Measurements included water potential, stomatal conductance, chlorophyll content, as well as visual turfgrass quality. Climatic parameters were measured by an eddy covariance system which measured evapotranspiration of the entire turf area. Soil moisture content was also measured. As expected during drought stress, water potential, stomatal conductance, chlorophyll content, and visual quality decreased as drought stress increased, especially during summer months and high ET conditions. We will correlate real-time ET parameters, as measured by the eddy covariance system, with these plant responses during spring, summer, and fall seasons. Our data will be used to improve irrigation scheduling of turfgrass irrigation.