Salinity tolerance and salt gland excretion efficiency of bermudagrass turf cultivars

Need for salt tolerant turfgrasses is increasing due to government mandates requiring use of low quality, secondary water sources for turfgrass irrigation. Objectives of this study were to determine the range in salinity tolerance among modern Cynodon spp. (bermudagrass) turf cultivars, determine if leaf salt gland excretion is an important salinity tolerance mechanism in bermudagrass, and if salinity tolerance is associated with the rate, or efficiency of leaf salt gland excretion. Salinity responses of thirty five bermudagrass turf cultivars [Cynodon dactylon (L.) Pers, and C. dactylon x Cynodon transvaalensis (Burtt-Davey)] were determined by exposing plants to five salinity levels (0, 15, 30, 45, and 60 dS m^-1). Salinity tolerance among cultivars was determined by shoot dry weight reduction relative to control plants and by percent green leaf canopy area (GLCA). Salinity resulting in 50% reduction in shoot dry weight (SW50) ranged from 26 to 40 dS m^-1, indicating a wide range in salinity tolerance within this genus. Salt glands were present on both abaxial and adaxial leaf surfaces of all cultivars. Salinity tolerance was negatively correlated with leaf tissue Na⁺ concentration and positively correlated with leaf salt gland Na⁺ excretion rate, indicating that salinity tolerance in bermudagrasses is associated with shoot saline ion exclusion and to leaf salt gland excretion efficiency.