Physiological response of two turfgrass species
to varying ratios of soil matric and osmotic potentials

D.E. Dean
D.A. Devitt
L.S. Verchick
R.L. Morris

ABSTRACT

    Plants grown under saline conditions can experience both elevated matric and osmotic stress during the time between irrigation events.  Research was conducted to assess the physiological response of tall fescue (Festuca arundinacea Schreb 'Monarch') and an improved common bermudagrass (Cynodon dactylon L. 'Numex Sahara') to varying combinations of soil matric and osmotic potentials.  Two line sorce gradient experiments were conducted, one used municipal water with an EC of 1.1 dS m^-1 and the other used saline aquifer water blended with municipal water to an EC of 6.0 dS m^-1.   Turf temperature, leaf xylem water potential, tissue osmolality, yeild, evapotranspiration (ET_a), percent cover, turf color, and tissue ion consentrations were monitored during a 68 day drydown period during the summer of the second year of experimentation.  The total soil water potential was highly linear with distance from the line source with no significant difference between fresh and saline treatments within each species (bermudagrass Adj r² = 0.867, tall fescue Adj r² = 0.810).  Significantly lower soil osmotic potentials were recorded under the saline treatment, while lower soil matric potentials were recorded under the fresh treatment for both species.  Turf temperature, yield, ET_a, turf color, and canopy cover responded to soil matric and osmotic potentials in an additive fashion.  However, leaf xylem water potential and tissue osmolality and tissue ion concentrations in bermudagrass and tissue osmolality and tissue ion concentrations in tall fescue responde ina non-additive fashion to soil matric and osmotic potentials.  Our results suggest that water with a salinity level of 6.0 dSm^-1 could be used as a supplemental irrigation source for both tall fescue and bermudagrass under the experimental conditions described in this study if irrigation practices were designed to minimize water deficit conditions.

Article is currently being published, 1997
for more information please contact Dr. Dale Devitt

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