| Experiments were initiated to determine the effects of NaCl, KCl, Na 2SO4 and K2SO4 at 0, −0.75, −1.00, and −1.50 MPa on germination and growth of Atriplex prostrata . Germination decreased as the osmotic potential became more negative, but a specific ion effect was not observed. Most ungerminated seeds pretreated with salts germinated after being placed in distilled water. Survival was lower in K+ salts of Cl− and SO4 2− than in their Na+ salts. Growth decreased as osmotic potential was lowered, and K+ salts were more inhibitory than Na+ salts to biomass, leaf, branch, and node production. Ionic content of tissues increased with a reduction in osmotic potential. Inhibitory effects of salts on growth parameters and survival followed the pattern; K2SO4 > KCl > Na2SO4 = NaCl. Sodium chloride treated plants had a higher glycinebetaine content than did the control at −0.75 and −1.00 MPa, but not at −1.50 MPa. Within each osmotic potential (−0.75 to −1.5 MPa), glycinebetaine content was higher in Na+ than K+ treated plants.; The effect of biotic interference on species distribution along an experimental salinity gradient was investigated using a deWit replacement series. Salicornia europaea was a better competitor at high salt concentrations and A. prostrata was a better competitor at low salt concentrations.; An inundation experiment was carried out to determine the effect of different levels of submersion on the growth and survival of A. prostrata and S. europaea. Complete submergence caused 100% mortality for both species within one week. There was no significant difference in biomass production between the root submersion and the emergent treatment.; Seed pools in an abandoned well field of the Morton Salt Company were monitored to determine if halophytes maintained a persistent seed bank. The total number of seeds of A. prostrata and Salicornia europaea decreased throughout the course of the growing season, and 5:25°C was optimal for germination. Seed banks in zonal communities contained species from all vegetation zones, indicating that soil salinity concentrations could control their species composition. In the four zones, Salicornia, Salicornia-Atriplex, Atriplex, and Atriplex-Hordeum, seed banks had a relatively low similarity to the above ground vegetation.; Plants were treated with NaCl, KCl, Na2SO4 and K2SO4 (0.00, 100, 300, and 600 mM) for 4, 12, and 24 hours to determine if accumulation of mRNA for an H+-ATPase plasma membrane transport protein occurred. The 100 mM treatment signals were equal to that of the control in a Northern analysis. No accumulation of mRNA was found at higher salinities, and there was some indication of inhibition of activity. |
