IRRIGATION FREQUENCY AFFECTS ZOYSIAGRASS ROOTING AND PLANT WATER STATUS

'Meyer' zoysiagrass (Zoysia japonica Steud.) was established on a silt loam soil in 27-cm-diameter x 92-cm-deep containers in a greenhouse t o investigate the influence of irrigation frequency on turfgrass rooti ng and drought tolerance, Turf was irrigated daily or at the onset of leaf rolling with a water volume equal to the cumulative evapotranspir ation of well-watered turf in small weighing lysimeters, After >90 day s of irrigation treatments, a dry-down was imposed during which no add itional water was applied for 55 days. A recovery period followed duri ng which time turf was watered to maintain soil matric potential at gr eater than -30 kPa, Compared to turf irrigated daily, that watered at the onset of leaf rolling exhibited 1) 32% to 36% lower leaf water pot ential and 14% to 22% lower osmotic potential before the onset of drou ght; 2) 13% higher leaf water potential approximate to 40 days into dr y-down; 3) more extensive rooting at 55- and 75-cm soil depths as indi cated by 11% to 19% lower volumetric soil moisture content at the end of dry-down; 4) 25% to 40% lower shoot growth rate during irrigation a nd 13% to 33% higher shoot growth rate during dry-down; and 5) higher quality ratings during dry-down and recovery. Thus, deep, infrequent i rrigation better prepares zoysiagrass for an oncoming drought than lig ht, frequent irrigation.