NaCl-induced changes in protoplasmic characteristics of Hordeum vulgare cultivars differing in salt tolerance

Water permeability and cytoplasmic viscosity and streaming were investigated in seedlings of two Hordeum vulgare cultivars differing in salt tolerance. Six-day-old seedlings were grown for 4 additional days in Hoagland solution with and without 100 m M NaCl added.
Observations and measurements were made in subepidermal cells of the coleoptile using plasmolytic and centrifugation methods and recordings of the speed of movement of microsomes.
Water permeability was about the same in controls of both cultivars, and was decreased by NaCl stress, but decreased less in the tolerant cultivar. Cells from control plants of the stress tolerant variety had a higher cytoplasmic viscosity than cells from the moderately sensitive cultivar. Cytoplasmic viscosity in both cultivars decreased due to NaCl stress, and more so in the sensitive one. Cytoplasmic streaming was faster in the controls of the salt sensitive cultivar than in controls of the salt tolerant cultivar; NaCl had no significant effect on cytoplasmic streaming in both cultivars.
The specific responses of the cytoplasm of the sensitive and tolerant cultivars to the salt treatment reflect differences in its structure and composition. These differences in the cytoplasm already exist before exposure to salt stress but some alterations of cytoplasmic parameters (e.g. water permeability) were induced by the saline environment.