ABSTRACT
Water conservation on golf courses is a primary concern as we enter the 21st century. Reduced water loss through decreased evapotranspiration (ET), and enhanced water uptake by an extensive root system are two possible mechanisms imparting drought avoidance in turfgrasses. However, research to date has not established a clear relationship between Poa pratensis L. ET and drought avoidance. Additionally, few field studies have related root distribution to drought avoidance of Poa pratensis cultivars. Two field studies were conducted to investigate these relationships. Evapotranspiration of four cultivars differing in drought avoidance was measured during the summers of 1994 and 1995 using microlysimeters. Root samples of six cultivars differing in drought avoidance were collected in 1992 and 1993 from the 0 to 15, 15 to 30, and 30 to 45 cm soil layers, and root mass and distribution were determined. There were no significant differences in ET rates among cultivars, thus, ET rates were not related to drought avoidance of Poa pratensis in these studies. Root distribution was associated with drought avoidance more consistently than root mass. Cultivars with good drought avoidance had a higher percentage of their total root system in the 30 to 45 cm soil layer during both years of the rooting study, but had significantly higher root mass at that depth only in the second year.
