Physiological Responses to Salt Stress By Warm-Season Turfgrasses with Contrasting Salinity Tolerance.

The increased need to understand physiological mechanisms of halophytic turfgrass species with potential use in salt-affected soils continues due to increased demand of non-potable water in arid and semi-arid regions. Greenhouse screenings were conducted during 2014 and 2015 at Texas A&M University, College Station TX to determine relative salinity tolerance among 45 experimental entries representing four warm-season turf species under salinity levels ranging approaching 45 dS m^-1. In 2016, 8 entries (two entries representing the highest and lowest relative salinity tolerance from each species) were advanced for additional evaluations aimed at determining physiological responses to salinity.  Entries included ‘Celebration’ and ‘UGB79’ bermudagrass (C. dactylon and C. dactylon x C.transvaalensis, respectively), ‘DALZ1313’ and ‘Zeon’ zoysiagrass (Zoysia matrella x Z. japonica and Z. matrella, respectively), ‘UGP3’ and ‘UGP38’ seashore paspalum (Paspalum vaginatum), and ‘Floratam’ and ‘Palmetto’ St. Augustinegrass (Stenotaphrum Secundatum). Grasses were grown in the greenhouse over 10 weeks at salinity levels of 0, 15, and 30 dS m^-1 to evaluate responses to increasing salinity.  EC₅₀, salt gland density, ion excretion efficiency, Na and Cl concentrations, and root and shoot tissue Na:K were determined. Results showed that all grasses adjusted osmotically under increasing salinity. Differences in the relative increase in Na:K were noted among species, with bermudagrass and seashore paspalum entries maintaining proportionally higher K under salinity stress. Differences in total ion excretion as well as tissue Na and Cl concentrations appear to contribute to the previously observed differences in salinity tolerance between species.