Effect of soil salinity on stomatal conductance and photosynthesis of green ash (Fraxinuspennsylvanica)

Abstract

Seedlings of green ash (Fraxinuspennsylvanica Marsh.) were subjected to four levels of salt water ranging from approximately seawater concentration to one-tenth the concentration of seawater to simulate a temporary intrusion of salt water in coastal areas and brine spills associated with oil-drilling activities. The effect of saltwater influx on subsequent stomatal behaviour and net photosynthesis was studied. Stomatal conductance was reduced up to 72% and net photosynthesis declined by as much as 86% in response to the application of saline water. Both responses were rapid and occurred shortly after treatment. In addition to substantial declines in stomatal conductance and net photosynthesis, plant water potential also declined after treatment. All levels of salt application resulted in leaf injury and the two highest concentrations caused rapid seedling mortality. The results of this study indicate that green ash seedlings are extremely sensitive to soil salinity and will not survive either saltwater intrusion or brine spills associated with oil-drilling activities. Potential long-term effects are discussed.