Comparative Responses of Bermudagrass and Seashore Paspalum Cultivars Commonly Used in Egypt to Combat Salinity Stress

In Egypt, salt-related problems have increased in the turfgrass industry during the last 30 years and the need for salt tolerant turfgrasses has increased. Two species of turfgrasses, bermudagrass (Cynodon dactylon L., 'Tifway', 'Tifdwarf' and 'Tifgreen') and seashore paspalum (Paspalum vaginatum Swartz, 'Salam', 'Excalibur', and 'Adalayd'), were studied in a greenhouse to evaluate their performance under various electrical conductivity (EC) levels [2.2 (control); 8.0, 16.0, 32.0, 44.0 and 54.0 dS m(-1)] of equal weights of CaCl2 and NaCl salinity in the culture medium. 'Salam' was found to have superior salt tolerance compared the others. 'Excalibur also exhibited high salinity tolerance, and both were better than 'Tifgreen', 'Tifdwarf', 'Tifway', Ind 'Adalayd'. Under the highest salinity level (54.0 dS m(-1), 'Salam' showed the lowest leaf firing percentage (80%) followed by 'Excalibur' (90.5%) while all others showed 100.0 % leaf firing. Only 'Salam' showed acceptable turf quality (6.0) at the salinity level of 32.0 dS m. 'Salam', 'Excalibur' and 'Tifgreen' quality declined less severely with increasing salinity, while 'Adalayd' had the poorest quality among all cultivars. At the salinity level of 16.0 dS nil, all tested cultivars showed acceptable quality except 'Tifway' and 'Adalayd'. 'Salam' and 'Excalibur' exhibited higher clipping yields than the others. 'Adalayd' had the lowest clipping yield at all salinity levels. Linear regression indicated a significant positive linear relationship between root mass and growth medium salinity levels in all tested turfgrass cultivars except 'Adalayd'. 'Adalayd' exhibited a decrease in root mass as salinity increased from 16.0 to 32.0 dS m(-1). At the highest salinity level (54.0 dS m(-1)), 'Salam' exhibited the highest root activity among all cultivars and maintained an increasing linear trend. For 25% clipping yield reduction, salinity levels ranged from 10.5 dS m(-1) for 'Adalayd' to 30.0 dS m(-1) for 'Salam' and these levels were significantly different among the tested cultivars.