Effects of temperature and light on salinity tolerance during germination in two desert glycophytic grasses, Lasiurus scindicus and Panicum turgidum

The grasses Lasiurus scindicus and Panicum turgidum are among the most important forage species of the Arabian deserts. Both are ‘glycophytic’ or salt-intolerant species, where seed germination becomes reduced by salinity effects. Here, we report experimental effects of light/darkness, temperature and NaCl salinity on seed germination and ‘recovery’ germination in these two species, after seeds had been transferred from saline solution to distilled water. Seeds were germinated in a range of salinities and incubated at a range of temperatures, in both light and darkness. Seeds of P. turgidum germinated significantly more in darkness than in light at temperatures 15–25°C, but the reverse was true at higher temperatures. Seeds of L. scindicus germinated well across a wide range of temperatures and in both light and darkness. In both species, germination decreased with the increase in salt concentration, and in P. turgidum germination was almost completely inhibited at a concentration of 200 mm. In saline solution, germination in darkness was significantly greater than in light at all the temperatures. Seeds of both species ‘recovered’ their germination capacity after transfer from saline solutions to distilled water. Germination recovery depended on both light and temperature of incubation in both species.