Gender and clonal variability in water relations and salinity tolerance of saltgrass (Distichlis spicata) planted for dust contol on the Owens Lake playa

Saltgrass (Distichlis spicata) is a salt tolerant, dioecious native grass that has been planted for dust control on the Owens Lake playa, the largest point source of particulate matter (PM₁₀) pollution in the western hemisphere.  There is a need to better understand the basic biology of this species to effectively manage the planted population for best dust control.  We treated twenty genotypes collected from the playa population with six NaCl concentrations (7, 150, 250, 350, 450, and 550 mMol) for five weeks and measured water potential, osmotic adjustment, sodium exudation rates, and growth.  We measured significant differences among treatments in all of these parameters.  Females had lower water potential than males under the same treatment conditions, indicating that they may have experienced greater stress. There were no significant differences among genotypes in water potential or osmotic adjustment.  Sodium exudation rates did not differ between genders but did vary significantly among clones, indicating that different genotypes have differing salt excretion capabilities.  Growth measurements will be analyzed for differences among genotypes and between genders to determine absolute levels of salt tolerance in the playa population.  Differences in stress tolerance between genders may have important management implications if, like natural populations, playa populations are segregating by gender along environmental gradients.