Influence of salinity and temperature on seed germination rate and the hydrotime model parameters for the halophyte, Chloris virgata, and the glycophyte, Digitaria sanguinalis

Effects of salinity, temperature and their interactions on final percentage and the rate of germination were evaluated for two grasses, the halophytic Chloris virgata and the glycophyte, Digitaria sanguinalis. Seeds were germinated in 0, 50, 100, 150, 200 and 250 mM NaCl solutions under constant temperatures of 15, 20, 25, 30 °C and alternating temperatures of 15/25 and 20/30 °C with a 12 h photoperiod. In D. sanguinalis, the hydrotime model described the time course of seed germination well; however, it provided a poor description of C. virgata germination. In both species, most of the un-germinated seeds transferred to distilled water were still viable. Results suggest that seeds take salt up, causing inhibition of germination at sub-toxic concentrations; however, when returned to pure water, this extra salt may be able to increase germination rates and percentages.

► We compare the different responses of halophyte and glycophyte species to salinity and temperature.
► We apply the hydrotime model to fit the data.
► We find the model fits the data well for D. sanguinalis but underestimates germination percentage and rate of C. virgata.
► We suggest the halophyte C. virgata develops physiological mechanisms to regulate salt entry and promotes germination.