Effects of Salinity on Seashore Paspalum Turfgrasses1

Increased need for salt tolerant grasses continues due to increased restrictions on limited water resources and to salt water intrusion into groundwater. Seashore paspalum (Paspalum vaginatumSwartz.) is used in Australia as a salt tolerant turfgrass, and cultivars are commercially available in the USA. The purpose of this investigation was to document the glasshouse response of four Seashore paspalum turfgrasses to solution cultures differentially salinized with synthetic sea water. A sea salt mixture was added to half‐strength Hoagland's number 2 nutrient solution to provide six salinity treatments ranging from 0.9 to 39.7 dS m−1. A split‐plot design with five replications was utilized to study salinity as the main plot effect and grass as the sub‐plot effect. Turfgrasses differed markedly in salt tolerance. Based on inverse regression analyses, the most salt tolerant experimental selection was FSP‐1 with 50% of its top growth reduced at 28.6 dS m−1; FSP‐2 and ‘Futurf’ were intermediate in salt tolerance with 50% top growth reductions at 21.9 dS m−1; whereas ‘Adalayd’ (‘Excaliber’) was the most sensitive cultivar with 50% top growth reduction at 18.4 dS m−1. The FSP‐1 selection was 3.1 times more salt tolerant than the other grasses when top growth was reduced only 5% at low salt concentrations. Salinity differentially affected tissue content of Ca, C1, K, Mg, and Na between grasses but had no affect on N which averaged 37.3 g kg−1. Maximum tissue content of 22.3 g kg−1of CI and 16.4 g kg−1of Na were at a salt concentration of 31 dS m−1in FSP‐1. However, concentrations of Cl and Na in the other grasses increased linearly 0.4 and 0.5 g kg−1, respectively, with each increase in salinity concentration. Maximum accumulation in this group was at the highest salt treatment of 39.7 dS m−1where Cl varied between grasses from 24 to 31 g kg−1and Na varied from 20 to 24 g kg1. Tissue content of Ca, K, and Mg decreased with increased salinity and differed between grasses. No mortality was observed although top growth of all grasses was severely reduced at the highest salt level.