Physiological Responses and Tolerance Mechanisms of Turfgrasses Exposed to Drought and Salt Stresses with Similar Osmotic Strength.

Physiological Responses and Tolerance Mechanisms of Turfgrasses Exposed to Drought and Salt Stresses with Similar Osmotic Strength

Krishna B. Katuwal, Bo Xiao, and David Jespersen

K.B. Katuwal and D. Jespersen, University of Georgia, USA; B. Xiao, Yangtze University, China

Salinity and drought stresses are two major abiotic stresses that cause severe damage to turfgrasses. Both stresses affect plants by creating osmotic imbalances or osmotic stress at the plant root-soil interface. Plants might use similar physiological responses and tolerance mechanisms to tolerate both salt- and drought-induced osmotic stresses. Seashore paspalum (Paspalum vaginatum) and centipedegrass (Eremochloa ophiuroides) are two popular warm-season turfgrass species with differences in their ability to tolerate salinity stresses. Little information is available about how mechanisms responsible for tolerance to osmotic stresses are activated under different conditions. Therefore, the objective of this study was to understand physiological responses of seashore paspalum and centipedegrass under both salt and drought stresses with similar osmotic strength. Individual tillers of seashore paspalum and centipedegrass were grown in ½ strength Hoagland’s nutrient solution. Three different treatments, salt stress via the addition of NaCl, drought stress using Polyethylene glycol and a non-stress control, were applied. Both salt and drought stress treatments had equal osmotic potentials of - 0.4 MPa. Results showed greater reductions in relative water content and chlorophyll fluorescence in drought stressed plants compared to salt stressed ones for both seashore paspalum and centipedegrass. However, osmotic adjustment was greater in seashore paspalum than centipedegrass under both conditions. Sodium accumulation was found in both roots and leaves of salt stress plants, while potassium content was higher in only the roots of drought stress plants. Higher contents of these inorganic ions in stress treatments indicated their important roles in osmotic adjustment of plants to survive stressful conditions.