Turfgrass rooting characteristics of ‘Palmetto’, ‘FX-10’, and ‘Floratam’ St. Augustinegrasses and ‘Pensacola’ bahiagrass

Abstract

St. Augustinegrass [(Stenotaphrum secundatum (Walt.) Kuntz] and bahiagrass (Paspalum notatum Flügge) are the two dominant lawn grasses maintained in Florida. Knowledge of relative drought resistance among species and cultivars is important for selecting turfgrass that will persist during drought stress. This study was designed to monitor the rooting characteristics of three St. Augustinegrass cultivars and one bahiagrass cultivar during the year following establishment. In spring 1995, sods washed free of soil were established in clear, sand-filled lysimeters. Rooting characteristics were monitored each month. After 90 days of growth, grasses were evaluated for drought tolerance by initiating a series of soil dry-down cycles. Roots of ‘Pensacola’ bahiagrass and ‘Floratam’ St. Augustinegrass reached a 60-cm depth in 90 and 180 days following sodding, respectively. ‘Palmetto’ and ‘FX-10’ St. Augustinegrass roots did not grow below 40 cm during the first 180 days following sodding. Roots of ‘FX-10’ St. Augustinegrass extended deeper than 40 cm after 240 days of growth; whereas roots of ‘Palmetto’ St. Augustinegrass never extended below 40 cm during this study. All grasses showed a general increase in root number at 20 cm within the first 180 days of growth, but at the 30-cm depth, root numbers remained relatively constant after 90 days of growth. The greatest changes in root length density (RLD) occurred during the first 150 days following sodding. ‘Floratam’ St. Augustinegrass and ‘Pensacola’ bahiagrass consistently had greater RLD in the 20- to 40-cm range compared to ‘Palmetto’ and ‘FX-IO’ St. Augustinegrasses. The number of days before wilt for ‘Pensacola’ bahiagrass, ‘FX-lO’, ‘Floratam’, and ‘Palmetto’ St. Augustinegrasses were 9.0, 6.7, 6.0 and 4.7, days respectively. The number of days to wilt was positively correlated (P=0.05; r=0.53) with root COWlt at the 30-cm depth, but it was not correlated with root count at the 20-cm depth.