Effect of salinity, light, and temperature on germination in Allenrolfea occidentalis

Allenrolfea occidentalis (S. Wats.) Kuntze, a halophytic perennial shrub in the family Chenopodiaceae, is widely distributed in inland salt marshes an d salt playas of western North America. Experiments were conducted to deter mine the effects of NaCl, light, and temperature on seed germination and th eir recovery of germination from saline conditions after being transferred to distilled water. Seeds of A. occidentalis were germinated at various tem peratures (5:15, 10:20, 10:30, 15:25, 20:30, and 25:35 degrees C (night:day )) and salinities (0, 200, 400, 600, 800, and 1000 mM NaCl) in a 12 h Light : 12 h dark photoperiod and in 24 h darkness. Increases in NaCl concentrat ion progressively inhibited seed germination, and this inhibition was great er in the dark than in light. No seeds germinated at concentrations higher than 800 mM NaCl. Cooler temperatures significantly inhibited germination i n all treatments, while regimes of high night (25 degrees C) and high day ( 35 degrees C) temperatures showed higher germination. Rate of germination d ecreased with an increase in salinity. Germination rate was higher at 25:35 degrees C and lower at 5:15 degrees C. Seeds were transferred from salt so lutions to distilled water after 20 days, and those from high salinities re covered quickly at all temperature regimes. Recovery germination percentage s at higher salinities varied from 51 to 100% at various temperatures, but recovery of germination of seeds from salt stress was significantly affecte d by temperature regime.