Salinity, temperature and light affect germination of Salsola imbricata

Salsola imbricata (Chenopodiaceae) is a common succulent dwarf shrub growing in the coastal ecosystems of the Arabian Gulf region. The impacts of light, temperature and salinity were evaluated for fresh seeds collected from a big population on coastal sand dunes in the United Arab Emirates (UAE). Seeds were germinated in seven salinities (0, 100, 200, 300, 400, 500 and 600 mM NaCl) at 15, 20, 25 or 35°C. The highest germination was at 20°C (77.5%) and the lowest was at 35°C (23.3%). Germination in dark was significantly greater than in light at 15°C, but no significant difference was observed at the other temperatures. Both final germination and germination rate decreased with the increase in salinity. Salinity tolerance during germination depended on temperature. The highest tolerance achieved at 20°C. Most of the non-germinated seeds at the different salinities recovered their germination when transferred to distilled water. Germination recovery was significantly greater at 15°C and significantly lower at 35°C than other temperatures. The ability of S. imbricata seeds to maintain their viability during exposure to seawater salinity level (600 mM NaCl) and to recover their germination after transfer to distilled water indicates that the effect of NaCl is more likely to be a reversible osmotic inhibition of germination, rather than ion specific toxicity.