Salinity Tolerance among a Large Range of Bermudagrasses (cynodon Spp.) Relative to Other Halophytic and Non-Halophytic Perennial C4 Grasses

The increasing demand on potable water has resulted in a greater reliance on poorer quality water, including saline sources, for maintaining forage and turfgrasses in agricultural and urban landscapes. Consequently, it will be crucial to identify grasses that can tolerate saline irrigation water. This study aimed to determine salinity tolerance among a large range of bermudagrasses relative to other perennial C-4 grasses and test the relationship between salt tolerance and drought resistance. We report the salinity tolerance of 70 genotypes of mostly Australian bermudagrass ecotypes that were compared to halophytic cultivars of seashore paspalum (Paspalum vaginatum Swartz) and a non-halophytic cultivar of Queensland blue couch (Digitaria didactyla Willd) using a flood and drain sand culture system with salt treatments 1-40 dS m(-1). For the first time for C-4 grasses, salt tolerance was determined by comparing total biomass of the grasses with and without salt treatment. Large genetic variation in salinity tolerance was identified and six bermudagrasses collected from saline habitats had salinity tolerance equal to that of seashore paspalum under the salinity treatments used in this study. There was no correlation between salt tolerance and drought resistance phenotypes determined from our previous research. Canopy temperature differential during salt stress was negatively correlated (r = -0.71 to -0.91, P < 0.001) to salt tolerance and has potential to be used for screening bermudagrasses for salt tolerance using flood and drain sand culture. Salinity levels above 20 dS m(-1) for 8 weeks appeared to be effective for detecting large variation for salt tolerance in bermudagrass.