Abstract

Little information is available concerning turfgrass water relations characteristics in response to salinity. Two greenhouse studies were conducted at Colorado State University to determine if water relations characteristics were associated with salt tolerance of Kentucky bluegrass (KBG), tall fescue (TF), alkaligrass (AG), and saltgrass (SG). Grasses were grown in saline solution at 2.0, 4.7, 9.4, 14.1, 18.8, and 23.5 dS/m. Salinity reduced leaf water content (LWC) of all species. The pressure potential (Y_P) of KBG, TF, and AGdecreased with increasing salinity, whereas SGY_P did not change. Osmotic adjustment (OA) occurred in all grass species under salinity stress, however, in KBG and TF, the contribution of Na⁺ and Cl^- to OA increased and these ions became the major contributors at high levels of salinity, whereas Na⁺ and Cl^-contributions to OA in SG were maintained at stable levels. Saltgrass showed the highest proportion of K⁺ at all levels of salinity than other grasses. As salinity increased, the contribution of unidentified osmolytes to OA increased in SG and decreased in KBG and TF. These interspecific differences in water relations may be, in part, attributed to the different salinity tolerance observed in these grasses.

Key words: Turfgrass, osmotic adjustment, Kentucky bluegrass, tall fescue, alkali grass, salt grass, leaf water potential, leaf osmotic potential, leaf pressure potential, salinity tolerance.