Evapotranspiration Rates of Riviera and U-3 Bermudagrasses Under Non-Limiting Soil Moisture Conditions.

Use of adapted bermudagrass cultivars with reduced evapotranspiration rates is one method of reducing turfgrass water use. ‘Riviera’ and ‘U-3’ (Tulsa Grass & Sod Farm source) were evaluated for their evapotranspiration (ET) rates under non-limiting soil moisture conditions at Stillwater OK during August through October 2010. Mini-lysimeters constructed from 15.3 cm dia PVC pipe and measuring 30.5 cm deep were used for assessing ET. Fritted clay was used as the root zone medium. Lysimeters were placed in 2.4 x 2.4 m field plots for measurement. The field experiment was designed as a randomized complete block with 3 replications. Lysimeters were fit into PVC plastic pot sheaths in the ground and leveled with pea gravel to assure appropriate lysimeter height. Turfgrass plots and lysimeters were mowed regularly at 5.1 cm. Lysimeters were saturated and allowed to drain to field capacity before being weighed pre-dawn and placed into the ground. Lysimeters were subsequently weighed to the nearest 1 gm, pre-dawn, once per day, for the next 4 days. Daily ET was determined by the loss in weight of water every 24 hours. ET measurements were analyzed using ANOVA. The analysis was conducted as a split plot in time with cultivars as main plots and measurement dates as subplots. Cultivar mean ET values were separated by LSD test at p = 0.05. Comparative cultivar ET rates under non-limiting soil moisture conditions will be discussed. The method was determined to be suitable for cultivar comparative ET. The technique will be utilized in 2011 and 2012 to assess ET of twenty bermudagrass cultivars under non-limiting soil moisture conditions in the field.