Abstract
The biophysical parameters controlling leaf growth were studied in context of salt stress. Various levels of NaCI, ranging from 25 to 250 mol m-3 , were used to salinize the medium. The parameters were measured in growing zone of the first emerged leaf of wheat seedlings (cv. Flanders, a British variety). In case of leaf elongation rate a two phase response was observed, i.e. an immediate decrease followed by subsequent recovery. The elongation rate decreased within 1 to 2 minutes of the stress onset and later started recovering after 1 to 2 hours and was almost fully recovered after 24 hours for all the NaCI concentrations. Turgor pressure measured in epidermal and mesophyll cells was about 0.45 MPa in control plant cells. The turgor pressure did not change after the salt addition (0 to 150 mol m-3 NaCl). However, it dropped when very high concentrations (200 and 250 mol m-3 ) of NaCI were applied to the medium. The salt stress did not have any effect on Instron tensiometric measurements (in vitro) of elastic and plastic extension of the cell wall.
