Glycinebetaine Seed Priming Improved Osmotic and Salinity Tolerance in Turfgrasses

Exogenous application of glycinebetaine (GB), an osmoprotectant, increases tolerance to stresses including salinity in various plants. Information on turfgrass, however, is limited. In this study, GB was used to prime turfgrass seeds to enhance salinity tolerance during germination and seedling growth stage when plants are more sensitive to stresses. Unprimed and primed (50, 100, 150, or 200 mm solution of GB or distilled water) seeds of perennial ryegrass (Lolium perenne L.) (PR), tall fescue (Festuca arundinacea Schreb.) (TF), creeping bentgrass (Agrostis palustris Huds.) (CB), and kentucky bluegrass (Poa pratensis L.) (KB) were germinated in solutions of distilled water, mannitol (causing osmotic stress only), or NaCl (causing both osmotic and ionic stresses). Their osmotic potential (psi(s)) and salinity level were -0.1 MPa and 0.1 dS.m(-1) (no stress), -1.0 MPa and 0.1 dS.m(-1) (moderate osmotic stress), and -1.0 MPa and 14.6 dS.m(-1) (moderate osmotic and ionic stresses), respectively. Seeds primed with GB showed a higher germination rate (11.0% to 13.9% increase) and seedling growth (19.3% to 20.7% increase) in mannitol or NaCl solution than in distilled water. Different turf species showed different responses to osmotic and ionic stresses. No differences in germination and seedling growth of PR, TF, and KB were observed between mannitol and NaCl treatments, indicating that osmotic stress appeared to more critical than ionic stress under saline conditions. For CB, the seed germination rate and seedling growth were lower (19.3% to 44.2% reduction) in NaCl than in mannitol, showing an accumulative effect of both osmotic and ionic stresses under saline conditions.