Growth Responses of Seashore Paspalum (Paspalum vagenitum Swartz) Under Salinity Stress Conditions.

Six cultivars of Seashore Paspalum (Paspalum vagenitum Swartz) (Aloha, Sea Dwarf, Sea Isle I, Sea Isle 2000, UG22, and Salam) were studied hydroponically using Hoagland solution in a greenhouse to evaluate their growth responses under various sodium chloride (NaCl) levels (EC 5, 10, 15, 20, 25, and 30 dSm^-1). Growth responses included shoot and root lengths, fresh and dry weights, and the grasses’ visual quality. A randomized complete block design with 4 replications was used in this study. During the experiment, shoots and roots’ lengths and shoot (clippings) fresh and DM weights were measured weekly and the grasses’ general qualities were evaluated. Roots were harvested at the termination of the experiment. The harvested materials were weighted fresh, then oven dried at 65^oC and DM weights were recorded. The results showed that there was no significant difference in the shoot lengths of 5 cultivars (Aloha, Sea Dwarf, Sea Isle I, Sea Isle 2000, and Salam), but UG22 had significantly lower shoot length compared to any of the other cultivars. In contrast, except at the EC 5 dSm^-1, there were significant differences found in root lengths of all the cultivars at any other level of salinity, Aloha had the longest roots at all these levels of salinity. There were significant differences found in shoot fresh and DM weights of the plants at each level of salinity. Aloha and Sea Dwarf had the lowest shoot fresh and DM weights at EC 5 dSm^-1 compared to the other cultivars, while at EC 10 dSm^-1, Aloha, Sea Isle I, and Salam had significantly lower shoot and root fresh and DM weights compared to the other 3 cultivars. At EC 15 and 20 dSm^-1, there was no difference found between the fresh and DM weights of the 6 cultivars. At EC 25 dSm^-1, Sea Isle 1 and Salam had the lowest fresh and DM weights compared to any of the other 4 cultivars, however at the highest level of salinity (EC 30 dSm^-1), Sea Isle 1 produced the lowest biomass compared to any of the other cultivars. There was no difference found between the qualities of the grasses at any level of salinity stress. However, as salinity level increased, the general quality of the grasses decreased. Although all the grasses exhibited satisfactory growth, Aloha did slightly better than the other cultivars and UG22 was slightly below the other cultivars. Overall, the results indicate that all these cultivars can be used under these relatively high saline conditions and still have satisfactory growth.