Growth and Physiological Responses of Bermudagrass to Salinity Stress

The need for salinity-tolerant turfgrasses is increasing owing to increased use of reclaimed or saline water for irrigation. The objective of this study was to investigate the salinity tolerance, growth, and physiological responses of four bermudagrass (Cynodon spp.) cultivars with different salinity tolerances. The salinity treatments (in Hoagland’s nutrient solution) were 0, 100, 200, 300, and 400 mmol·L⁻¹ NaCl. The reduction in relative shoot growth with increasing salinity indicated a salinity tolerance decreasing in the order of 'Riviera' > 'Blackjack' > 'Savannah' > 'Sundevil 2'. Shoot and root growth of all cultivars were significantly affected by NaCl stress. However, root length and root dry weight of the salt-tolerant cultivars Riviera and Blackjack increased significantly compared with the control. Tissue Na⁺ and Cl^– concentrations in all cultivars increased with increasing salinity. The most salt-tolerant cultivar, Riviera, accumulated less Na⁺ and Cl^– in leaves and roots and more K⁺ in leaves than the least tolerant cultivar, Sundevil 2. All cultivars had bicellular salt glands. 'Riviera' excreted more Na⁺ and Cl^– than the other cultivars through these glands. All grasses exhibited complete osmotic adjustment, and osmotic adjustment of 'Riviera' was less than other cultivars under salinity stress. Cultivars exhibited marked differences in their responses to salinity. Our results indicate that the salinity tolerance of bermudagrass is associated with leaf and root Na⁺ and Cl^– regulation, in conjunction with the maintenance of high leaf K⁺ levels and efficient excretion of Na⁺ and Cl^– by leaf salt glands.