COMPETITIVE GROWTH RESPONSES OF THREE COOL-SEASON GRASSES TO SALINITY AND DROUGHT STRESSES

This study was conducted in a greenhouse, using hydroponics system, to compare growth responses of three major sport turfgrasses, creeping bentgrass (Agrostis stolonifera), rough bluegrass (Poa trivialis), and perennial ryegrass (Lolium perenne) in terms of shoot and root lengths and dry matter (DM), and percent canopy green cover (%CGC) under salinity and drought stresses. Grasses were grown in Hoagland solution for 90 days prior to initiation of salinity or drought stresses. Then, 24 meq NaCl/L culture solution/day were added for each -0.1 MPa OP of salinity stress, or 75 and 119 g of PEG/L were added for -0.2 and -0.4 MPa OP of drought stress treatments, respectively. Five treatments (control, -0.2 and -0.4 MPa OP salinity, -0.2 and -0.4 MPa OP drought stress, and 4 replications of each treatment were used in a RCB design trial. During the stress period, shoots were clipped weekly for DM yield, shoot and root lengths were measured, and %CGC was evaluated. The weekly clippings and the roots at the last harvest were oven dried at 60°C and DM recorded. All 3 grasses were more severely affected by drought than salinity. Bluegrass was the most and bentgrass the least severely affected by either drought or salinity.