TURFGRASS QUALITY, GROWTH, AND WATER-USE INFLUENCED BY SALINITY AND WATER-STRESS

Limited water resources in the arid southwestern USA have created grea ter interest on the part of municipalities to utilize nonpotable water s in urban areas. Research was conducted to assess the feasibility of using a perched saline aquifer as an alternative irrigation source for turfgrass. Two line-source irrigation gradients, one using municipal water with an EC of approximate to 1.1 dS m(-1) and the other using sa line aquifer water blended with municipal water to an EC of 6.0 dS m(- 1), were established to impose a salinity and/or water deficit gradien t on tall fescue (Festuca arundinacea Schreb. 'Monarch') and an improv ed common bermudagrass (Cynodon dactylon L. 'Numex Sahara'). Yield was found to be highly correlated with actual evapotranspiration (ET(a) ( r = 0.92, P < 0.001 for bermudagrass; r = 0.83, P < 0.001 for tall fes cue), regardless of how the stress was imposed. Relative ET. (ratio of ET, to maximum ET. under municipal irrigation) values as a function o f the summation of the leaf-to-air temperature differences also indica ted no distinguishable change in stress response based on water qualit y (r = 0.94, P < 0.001 for tall fescue; r = 0.86, P = <0.001 for bermu dagrass). Relative turf color and percent cover remained unchanged if the ratio of irrigation volume to potential evapotranspiration (I/ET(0 )) remained above species-specific threshold values of 0.80 for tall f escue and 0.65 for bermudagrass. Below these thresholds, cover and col or declined linearly, with differences due to water quality treatment in tall fescue but with no differences due to water quality treatment in bermudagrass.