Germination of dimorphic seeds of Suaeda moquinii under high salinity stress

Suaeda moquinii (Torrey) Greene (desert blite), a succulent shrub in the fa mily Chenopodiaceae, is widely distributed in salt marshes of the western U nited States. Suaeda moquinii produces dimorphic seeds (soft brown and hard black). Both types of seeds were collected from a salt marsh in Faust, Uta h. Experiments were conducted to determine the seed germination responses o f the black and brown seeds to salinity and temperature. Brown seeds were f ound to be one of the most salt tolerant at the germination stage when comp ared to other halophytes. Brown seeds germinated (30%) at 1000 mM NaCl, but only a few black seeds germinated (8%) at 600 mM NaCl. Seed germination oc curred in most saline treatments at the lowest thermoperiod (5-15 degreesC) tested. In some salinity treatments (600, 800, 1000 mM), further increases in temperature resulted in progressively decreased seed germination. Brown seeds germinated better and had a higher germination rate (germination vel ocity) than black seeds at all thermoperiods. The highest rate of germinati on of black seeds occurred at the lowest thermoperiod (5-15 degreesC). Reco very of germination for black seeds when transferred to distilled water aft er being in various salinity treatments for 20 days was nearly complete (82 -100%) at the lowest thermoperiod (5-15 degreesC) but decreased with increa se in the temperature. Brown seeds recovered substantially (59-97%) from sa linity at all thermoperiods. Regression analyses indicated significant diff erences between the germination recovery of the black and brown seeds.