Tuesday, November 6, 2007 - 1:15 PM
168-2
Evapotranspiration, Consumptive Water Use, and Drought Tolerance of Three Warm-Season Grasses.
William Henry1, D.M. Kopec2, James Walworth2, Mohammad Pessarakli3, and Stephen Nolan1. (1) Soil, Water and Env. Sci., Univ. of Arizona, Room 303 Bldg 36 Plant Sci Dept, Univ. of Arizona, Tucson, AZ 85721, (2) University of Arizona, Department of Plant Sciences, Forbes Bldg., Room 303, Tucson, AZ 85721, (3) Forbes Bldg Room 303, University of Arizona, University of Arizona, Department of Plant Sciences, Tucson, AZ 85721
Lysimeters were used to assess evapotranspiration rates (ET) and consumptive water use among three desert turfgrasses grown under field conditions. Water use rates were compared for two relatively ‘new’ turfgrasses; ‘Sea Isle I’ seashore paspalum (Paspalum vaginatum) and A138 desert saltgrass (Distichlis spicata), along with ‘Tifway’ bermudagrass (Cynodon dactylon x Cynodon transvalensis) by using 90 cm deep gravimetric lysimeters. Lysimeters filled with calcined clay were planted with the three study grasses in June 2005. The experimental design was a randomized complete block (RCB) with four replications. Lysimeters were filled with water, and then allowed to drain twelve hours to reach soil field capacity. Lysimeters were weighed daily until the plants showed visible signs of stress (leaf curling, wilting, elevated leaf temperature, and or loss of color) at which point the lysimeters were brought back to non-limiting water conditions. ET was calculated from decreases in lysimeter mass. Reference ET was continuously measured with an on-site weather station. Saltgrass showed elevated leaf canopy temperatures for extended periods before exhibiting visible wilt symptoms while ‘Tifway’ bermudagrass and seashore paspalum wilted readily, even at relatively high soil water contents. Saltgrass was capable of lasting, 13.8 d on average, before requiring the next irrigation. Seashore paspalum was able to go, on average 7.6 d without watering, whereas ‘Tifway’ bermudagrass averaged 5.6 d before requiring irrigation based on the above criteria. Average cumulative ET for the three grasses for periods prior to removal of any lysimeters due to water stress was 32.2 mm, 30.1 mm, 28.3 mm, for saltgrass, paspalum, and 'Tifway' bermudagrass, respectively in 2006.