The influence of NaCl on leaf water relations and the proportions of K, Na, Ca, Mg, and Cl in epidermal cells of Fraxinus excelsior L.

The influence of NaCl on leaf water relations was investigated in 3-4-year-old, potted Fraxinus excelsior L. trees. Until midsummer, the application of NaCl to the soil resulted in increased leaf water potentials (Psi) and stomatal diffusive resistances (r(s)). The improved water status seems to be due to a latent injury rather than to an adaptive response of the plant because, despite the initial increases in Psi and r(s), leaf necrosis developed in midsummer. Altered hydraulic resistances were detected at the time the leaves became necrotic. X-ray analysis of frozen, hydrated leaf tissue from NaCl-treated trees showed substantial increases in Ca(2+) and Mg(2+) content in the epidermal cells. These changes in elemental composition of the leaves from NaCl-treated plants may be associated with malfunction of the stomatal apparatus.